Bimodal polyethylene composition and articles made therefrom

Description of the invention

The present invention relates to high-density polyethylene compositions with a bimodal molecular weight distribution and the use of such a composition in the manufacture of articles, especially tall top-fill blown articles, and high temperature or high pressure long life pipes.

Polyethylene pipes are lightweight, easy to handle and corrosion-free. In addition, they have a relatively high stiffness such that they can be laid underground, and a relatively high flexibility such that they can be subject to ground movements. Due to these valuable features, the amount of polyethylene pipes used has increased rapidly in recent years.

In addition to the above desirable properties, the polyethylene pipes should exhibit (1) an impact strength sufficient to withstand accidental impacts during assembly and afterwards; and (2) excellent long term durability under gas or water pressure (especially stress crack resistance and internal pressure creep resistance).

Regarding long-term durability, ordinary pipes can meet the ISO standard of 50 years at normal temperatures under internal pressure, expressed as hoop stress, around 8MPa. However, conventional polyethylene pipes still have an insufficient service life when used under more severe conditions such as gas or running water main pipes of large diameter and high internal pressure. For this reason, they are currently used only as pipes in branches etc. with a smaller diameter.

The durability of polyethylene pipes is determined by the resistance to stress cracking, that is, the resistance to cracking occurring when the internal pressure applied to the pipe acts as a circumferential tensile stress on the pipe over an extended period of time. Therefore, in order to improve the long-term durability of polyethylene pipes, the resistance to stress (tensile) cracking must be increased.

When using plastic pipes, hoop stress, as defined in ISO 9080 and ISO 1167, is an essential requirement. These procedures describe long-term creep cracking of plastic materials using extrapolation, predicting the hydrostatic resistance of the materials for pipes over 50 years at 20 ° C. Typically, when testing to determine long-term predicted performance characteristics, the test pipe materials are placed under different loads and the service life at a given temperature is determined. Tests are also performed at higher temperatures for extrapolation to 50 years at 20 ° C. The determined service life curves at each temperature typically include a high stress malleable fracture region corresponding to a shorter life, or a lower brittle fracture stress region corresponding to a longer service life. The tenacious nature of the failure is defined as Stage I failure, while the brittle failure is referred to as Stage II failure.

The first and second generation polyethylene pipes for water and gas distribution show the minimum required strength (MRS) for the corresponding hover stresses of 6.3 and 8 MPa and are denoted by the symbols PE63 and PE80, respectively. The third generation of polyethylene pipes, designated as PE100 pipes, corresponds to the value of MRS 10. The MRS value is based on the above ISO procedures, where a value of 10 means that pipes made of polyethylene materials must withstand a load of 10 MPa at 20 ° C for 50 years.

Another important performance requirement for long-life pipes or materials is Rapid Crack Propagation (RCP) resistance. The RCP of pipe material is usually measured by testing extruded pipe according to ISO 13477 (the so-called 'S4' test). However, the S4 test is not suitable for small scale evaluation, and therefore various small scale tests have been introduced in the plastic pipe industry. Small-scale tests include the inverse Charpy test and the Plane High-Speed ​​Double Torsion test, and classification tests such as the critical strain energy release rate test or the Gc measurement of compression molded materials. Moreover, the lower the brittle transition temperature Tdb of a material, the better its RCP resistance.

It is known to improve the stress crack resistance of a polyethylene composition by increasing the molecular weight or reducing the density of the polyethylene. However, as the molecular weight is increased, the fluidity of the polyethylene is decreased so that the properties deteriorate

Processing, such as tube extrusion and injection molding ability. When the density decreases, the stiffness of the polyethylene decreases adversely.

U.S. Patent No. 6,114,483 discloses mixtures of different polyolefins or branched polyolefins which are made by polymerizing one or more polymerizable olefins using two or more active transition metal catalyst catalyst systems, one of which preferably contains complexed far transition metals. with selected ligands. However, there is no indication that these catalyst systems are capable of producing polymers with low ductility-brittle transition temperatures or a reverse comonomer distribution.

WO-A-0022040 discloses Rapid Crack Propagation (RCP) polymer compositions with S-4 values ​​ranging from -19 ° C to 29 ° C. These polymers were prepared using Ziegler-Natta catalysts and did not have the reverse comonomer distribution.

While numerous pipe compositions are known and used, there remains a need for improved durable materials, particularly for the manufacture of pipes for the transmission and distribution of gases and water. Preferably, the materials should exhibit increased durability and / or service life at elevated temperatures. In particular, there is still a need for durable high-density polyethylene materials with improved resistance to slow crack propagation and / or fast crack propagation.

The bimodal polyethylene composition of the invention meets the above requirements. The new composition includes a low molecular weight (LMW) ethylene homopolymer component with a molecular weight distribution, MWD^L., less than 8 and a homogeneous high molecular weight (HMW) ethylene interpolymer and at least one olefin component. The composition has a bimodal molecular weight distribution and a brittle-ductile transition temperature, Tdb, below -20 ° C. Preferably, the overall Mw / Mn (molecular weight distribution index or MWD) of the new composition is relatively narrow and the Mw / Mn of the LMW component is relatively narrow, or the MWD of both the LMW component and the HMW component is also relatively narrow, or the MWD of both components are relatively narrow and completely different from each other. In some embodiments, the HMW component has a "reverse comonomer distribution".

Preferably the density of the LMW component is above 0.965 g / cm³and the I2 value of the LMW component, determined in accordance with ASTM D-1238 (2.16 kg / 190 ° C condition), is from 30 to 1000 g / 10 minutes.

Preferably the density of the HMW component is from 0.905 to 0.955 g / cm³and the I21.6 value of the HMW component, as determined according to ASTM D-1238 (21.6 kg / 190 ° C condition), ranges from 0.1 to 1.0, more preferably from 0.1 to 0, 6 or 0.6 to 1.0.

The HMW component of the composition preferably has a unimodal molecular weight distribution, MWD^H., 8 or less, preferably 5 or less, or is 3 or less than or 2, with preferably the MW / Mw being 1.3 or more.

Preferably the molecular weight distribution of the component which is a low molecular weight ethylene homopolymer, MDV^L. is 5 or less, 3 or less, or 2.

The polyethylene composition of the invention has a molecular weight distribution (MWD), defined as the ratio Mw / Mn, of 30 or less, and the HMW component has a substantially uniform comonomer distribution or an inverse comonomer distribution.

Preferably, the HMW component has a substantially uniform comonomer distribution characterized by a short chain branching distribution index (SCBDI) of greater than 70%.

In some embodiments, it is preferred that the HMW component has an inverse comonomer distribution characterized in that the molar comonomer content of the interpolymer fractions with an M w greater than or equal to 300,000 g / mol is at least 25% greater than the molar comonomer content of the interpolymer fractions with an M w less than or equal to 100,000. g / mol.

The preferred brittle-ductile transformation temperature, Tdb, of the composition of the invention is below -25 ° C, below -30 ° C, below -40 ° C, and even below -50 ° C.

Preferably, the molecular weight distribution, Mw / Mn of the composition, as determined by gel permeation chromatography, is less than or equal to 20.

The composition according to the invention preferably has a 21.6 / L5 ratio, determined according to ASTM D-1238 (condition 21.6 kg / 190 ° C and condition 5 kg / 190 ° C), of less than or equal to 22.5.

PL 203 864 B1

Preferably, the I21.6 index, determined according to ASTM D-1238 (21.6 kg / 190 ° C condition) of the composition according to the invention, is in the range from 3 to less than 50 g / 10 minutes, more preferably in the range from 3 to 12 g / 10 minutes, or in the range of 12 to less than 50 g / 10 minutes.

The composition according to the invention is also characterized by an I5 index, determined according to ASTM D-1238 (condition 5 kg / 190 ° C) in the range of 0.1 to 2 g / 10 minutes.

₃

The preferred density of the compositions according to the invention is above 0.938 g / cm³.

Preferably, the composition has a ratio Mv1 / Mv2 less than or equal to 0.6, where Mv1 is the viscosity average molecular weight of the LMW high density component, Mv2 is the viscosity average molecular weight of the interpolymer HMW component, and the determination is by ATREF analysis. -DV.

Also within the scope of the invention is a polyethylene composition comprising an ethylene polymer and copolymer and at least one conventional additive which comprises a low molecular weight (LMW) ethylene homopolymer component and a high molecular weight (HMW) ethylene interpolymer and at least one olefin, the polyethylene composition being has a bimodal molecular weight distribution, its molecular weight distribution, defined as the ratio Mw / Mn, is 30 or less than 30 and the HMW component has the reverse comonomer distribution.

Brief description of the drawings

Figures 1A-1C are graphs of the molecular weight distribution of bimodal polymers according to embodiments of the invention.

Fig. 2 is a schematic diagram of the creep crack test assembly used in the examples.

Fig. 3 is a plot of Gc versus PENT for the polymer of Example 6 of the invention compared to reference PE100 and PE80 resins.

FIG. 4 is a graph of the RCP (based on Gc data) for the polymer of the inventive example and comparative trials.

FIG. 5 is a plot of creep cracking for the polymer of the inventive example and comparative tests.

The novel polyethylene composition according to the invention can be used in the production of water or oil pipes and other products. The novel composition comprises a low molecular weight (LMW) ethylene homopolymer component and a high molecular weight (HMW) ethylene interpolymer component. The new composition has a relatively narrow bimodal molecular weight distribution. The bimodality of the molecular weight distribution of the new composition is due to the difference between the MWD of the LMW component and the HMW component. Preferably, the MWDs of each of the LMW and HMW components are unimodal but different and different from each other such that when mixed, the resulting composition exhibits a generally bimodal molecular weight distribution. The LMW ethylene homopolymer component has a molecular weight distribution, MWD^L., less than 8, and the new composition has a brittle transition temperature, Tdb, of less than -20 ° C. In some embodiments, the HMW component has a substantially uniform comonomer distribution or a reverse comonomer distribution.

The term "substantially homogeneous comonomer distribution" means that the comonomer content of the polymer fractions within the molecular weight range of the HMW component varies by less than 10% by weight, preferably 8% by weight, 5% by weight or 2% by weight.

As used herein, the term "homogeneous polymer" refers to polymerization products having a relatively narrow molecular weight distribution and having a comonomer content in chains of substantially the same molecular weight, not substantially different between the chains; in other words, the polymers exhibit a relatively even distribution of comonomers along the chain of a given molecular weight.

As used herein, the term "inverse comonomer distribution" means that across the molecular weight section of the HMW component, the comonomer contents of the different polymer fractions are not substantially uniform and the comonomer content of the higher molecular weight fractions is proportionally higher. Both substantially homogeneous and inverse comonomer distributions can be determined by fractionation techniques such as gel permeation chromatography-differential viscometry (GPCDV), temperature elevated elution fractionation-differential viscometry (TREF-DV) or cross fractionation techniques.

PL 203 864 B1

As used herein, the term "bimodal" means that the MWD in the GPC curve exhibits two constituent polymers, the constituent polymer may be a hump, shoulder or tail with respect to the MWD of another constituent polymer. Deconvolution of a bimodal MWD into two components, the HMW component and the LMW component, can be performed. After deconvolution, the half-maximum peak width (WAHM) and the mean molecular weight (Mw) of each component can be determined. Then, the degree of separation ("DOS") between the two components can be calculated from the following equation:

DOS = _M.^H._{- M.}^L. _^{, v,}in ^{, v,}in_

WAHM^h + wahm^l Where's m_in^H. them_in^L. are the weight average molecular weight of the HMW component and the LMW component, respectively; and WAHM^H. and WAHM^L. denote the peak width at half maximum on the deconvolved molecular weight distribution curve for the HMW component and the LMW component respectively. The DOS of the new composition is about 0.01 or greater. In some embodiments, DOS is greater than about 0.05, 0.1, 0.5, or 0.8. Preferably, the DOS for bimodal components is at least about 1 or greater. For example, DOS is at least about 1.2, 1.5, 1.7, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0. In some embodiments, DOS is about 5.0 to about 100, about 100 to 500, or about 500 to 1000. It should be emphasized that DOS may be any number within the above range. In other embodiments, the DOS exceeds 1000. Of course, in some embodiments, the "bimodal molecular weight distribution" can be successfully deconvolved such that more than two peaks will match. In some embodiments, the term "bimodal" does not include multimodal polymers, eg, LDPE.

In the description, the term "unimodal" in reference to the general MWD in the comparative examples or in reference to the MWD of the constituent polymer of the composition of the invention means that the MWD in the GPC curve essentially does not show many constituent polymers (i.e. in the GPC curve there are essentially no noticeable humps, arms or tails). In other words, DOS is 0 or essentially close to 0.

As used herein, the term "different" with respect to the molecular weight distribution of the LMW component and the HMW component means that the molecular weight distributions on the resulting GPC curve do not substantially overlap. This means that each molecular weight distribution is narrow enough and that the average molecular weights differ sufficiently so that the MWD of both components essentially shows a baseline on the high molecular side as well as on the low molecular side. In other words, DOS is at least 1, preferably at least 2, 4, 5, 7, 9 or 10.

In this specification, the term "interpolymer" means, for example, a copolymer or a terpolymer. This means that at least one other comonomer is polymerized with ethylene to form an interpolymer.

The molecular weight distribution, Mw / Mn, of the composition is preferably less than 20, more preferably less than or equal to 19, most preferably less than or equal to 18, especially less than or equal to 17.5, and exceptionally preferably from about 10 to about 17. , 5. In some embodiments, the MWD of the total composition is less than 10, e.g., about 5, about 7, or about 9. Alternatively, the composition preferably has an I21.6 / L5 ratio less than or equal to 22.5, more preferably less than or equal to 22, most preferably less than or equal to 21, most preferably less than or equal to 20.

A relatively narrow molecular weight bimodal polyethylene composition also has an overall density greater than or equal to 0.94 g / cm.³preferably in the range of about 0.94 to about 0.97 g / cm³, more preferably from about 0.948 to about 0.968 g / cm³, and an I5 melt index of less than or equal to 0.5 g / 10 minutes, preferably in the range of about 0.01 to about 0.5 g / 10 minutes, more preferably from about 0.05 to about 0.45 g / 10 minutes.

Alternatively, the novel composition can be characterized by a ratio Mv1 / Mv2 less than or equal to 0.8, preferably less than or equal to 0.6, more preferably less than or equal to 0.4, where Mv1 is the viscosity average molecular weight of the high density LMW component and Mv2 is the viscosity. the average molecular weight of the HMW interpolymer as determined by the ATREF-DV analysis detailed in WO 99/14271. WO 99/14271 also describes a suitable deconvolution technique for multi-component polymer blend compositions.

The new composition is characterized by a low brittle-ductile transformation temperature, Tdb. Tdb can be measured by the S4 test, sometimes referred to as the critical temperature measurement of rapid crack propagation. Tdb can also be determined from the critical strain energy release rate, Gc, measured on the Charpy system. Preferably, the Tdb is below -25 ° C, -30 ° C or

PL 203 864 B1 below, or -40 ° C or below. More preferably, the Tdb is -45 ° C or less. In some embodiments, the Tdb is -50 ° C or -60 ° C or less.

Certain new compositions also have exceptional slow crack propagation resistance as measured by the PENT test. Typically, the compositions described herein have a PENT pot life of about 110,000 minutes or greater at 2.4 MPa at 80 ° C. Preferably, the compositions have a PENT lifetime of about 150,000 to about 200,000 minutes or greater. Most preferably, the compositions have a PENT lifetime of about 250,000 to about 500,000 minutes.

The novel composition may substantially contain any amount of the LMW component or the HMW component such that each component may be present in an amount from about 0.5 to about 99.5% by weight. In some embodiments, the new composition comprises from about 35 to about 65% by weight. , preferably about 45 to about 55% by weight of the low molecular weight (LMW) high density ethylene homopolymer component. The LMW component has an I2 melt index of less than or equal to 2000 g / 10 minutes, preferably an I2 melt index of 30 to 2000 g / 10 minutes, more preferably 40 to 1000 g / 10 minutes, most preferably 50 to 150 g / 10 minutes. The Mw of the LMW component is preferably 10,000 to 40,000 g / mol, more preferably 25,000 to 31,000 g / mol. The Mw / Mn of the LMW component is preferably less than 8, more preferably less than 5, most preferably 3 or less. In other embodiments, the Mw / Mn of the LMW component is 2 or less. In some embodiments, the molecular weight distribution, Mw / Mn, of the LMW component is 1.5 to 4.8. In some embodiments, the Mw / Mn of the LMW component is most preferably 3.2 to 4.5. The density of the LMW component is preferably over 0.960 g / cm³, more preferably it is greater than or equal to 0.965 g / cm2³and most preferably greater than or equal to 0.970 g / cm³.

The novel composition comprises about 65 to about 35% by weight, more preferably about 55 to about 45% by weight of the high molecular weight (HMW) ethylene interpolymer component. The HMW interpolymer component has an I2 melt index of less than or equal to 0.1 g / 10 minutes, preferably an I2 melt index 0.001 to 0.1 g / 10 minutes, more preferably 0.005 to 0.05 g / 10 minutes, most preferably 0, 0085 to 0.016. The HMW component also has a melt index of I21.6 0.1 to 1.0 g / 10 minutes. In some embodiments, I21.6 is preferably 0.1 to 0.6 g / 10 minutes, preferably 0.1 to 0.5 g / 10 minutes, more preferably 0.3 to 0.4 g / 10 minutes. In other embodiments, I21.6 is greater than 0.6 to 1.0 g / 10 minutes, preferably 0.65 to 0.95 g / 10 minutes, more preferably 0.7 to 0.9 g / 10 minutes.

The Mw of the HMW component is preferably 100,000 to 600,000 g / mol, more preferably 300,000 to 500,000 g / mol, and most preferably 375,000 to 450,000 g / mol. Molecular weight distribution of the HMW component, MWD^H., may be wide, but is typically less than 8. In some embodiments, the MWD^H. is less than 5. Some preferred embodiments include a HMW component having a MWD^H. 3 or less, more preferably 2 or less.

Preferably, the density of the HMW component is 0.905 to 0.955 g / cm³. In some embodiments, the lower limit of a preferred density is about 0.910 or about 0.915 g / cm³ or about 0.920 g / cm³. ₃

In some embodiments, the upper limit of the density of the HMW component may be about 0.950 g / cm³, about 0.940 g / cm³ or about 0.930 g / cm³.

Preferably, the MWD of each component is unimodal, more preferably unimodal and different. Preferably, the ratio of the molecular weights of the HMW component and the LMW component, mW / mW, is 1.3 or greater.

In some embodiments, the Mw / Mn of the HMW component is relatively narrow. That is, preferably the Mw / Mn of the HMW component is less than 4.8, more preferably less than or equal to 4.5, most preferably about 1.5 to about 4 and most preferably about 2.7 to about 3.1. The density of the HMW component is less than or equal to 0.949 g / cm³, preferably less than or equal to about 0.945 g / cm³, more preferably, it is about 0.92 to about 0.943 g / cm2³.

In other embodiments, the HMW interpolymer component is a homogeneous polymer or has a substantially uniform comonomer distribution. Information regarding the relative homogeneity of the comonomer distribution of ethylene interpolymers is usually given as SCBDI (Short Chain Branch Distribution Index) or CDBI (Composition Scatter Width Index), which are used interchangeably herein. SCDBI is defined as the wt% of polymer particles having a comonomer content within 50% of the median total molar comonomer content and compares the comonomer distribution in the interpolymer with the comonomer distribution expected for a Bernoulli distribution. The SCBDI of the interpolymer can be easily calculated from the TREF as described, e.g., in Wild et al., Journal Polymer Science, Poly. Phys. Ed., Vol. 20, p. 441 (1982); U.S. Patent Nos. 4,798,081 and 5,008,204; or LD Cady, "The Role of Comonomer Type

PL 203 864 B1 and Distribution in LLDPE Product Performance ”, SPE Regional Technical Conference, Quaker Square Hilton, Akron, Ohio, October 1-2, pp. 107-119 (1985).

The preferred TREF technique does not include the cleansing amounts in the SCBDI calculations. More preferably, the comonomer distribution in the interpolymer and SCBDI is determined using analysis¹³C NMR, by the methods described in U.S. Patent Nos. 5,292,845, 4,798,081, and 5,089,321, and JC Randall, Rev. Macromol. Chem. Phys., C29, pp. 201-317.

In an analytical temperature-elevated elution fractionation analysis (described in US Patent No. 4,798,081, abbreviated herein as "ATREF"), the composition under analysis is dissolved in a suitable hot solvent (e.g., trichlorobenzene) and allowed to crystallize in a column containing neutral carrier (stainless steel shot) by slowly lowering the temperature. The column is equipped with both a refractive index detector and a differential viscometer (DV) detector. An ATREF-DV chromatogram curve is then generated by eluting a sample of the crystallized polymer from the column by slowly increasing the temperature of the eluting solvent (trichlorobenzene). The ATREF curve is also often referred to as the short chain branching distribution (SCBD) as it indicates how evenly the comonomer (e.g. octene) is distributed throughout the sample because as the elution temperature decreases, the comonomer content increases. The refractive index detector provides information on the short chain distribution and the differential viscometer detector provides an estimate of the viscosity average molecular weight. Short chain branching distribution and other composition information can also be obtained using a fractional crystallization analysis, such as the CRYSTAF fraction analysis package, commercially available from PolymerChar, Valencia, Spain.

Accordingly, when the comonomer distribution in the interpolymer component is substantially homogeneous, it has a SCBDI of greater than 50%, more preferably greater than 70%, and most preferably greater than about 90, 95, or 99%. The SCBDI determination will clearly distinguish these polymers from Very Low Density Polyethylenes (VLDPE), which typically have a broad composition distribution, as assessed by SCBDI values, which are typically below about 55%.

Preferably, the homogeneous copolymers have a substantially single melting point, with a peak melting point (Tm), as determined by Differential Scanning Calorimetry (DSC), of about 60 to about 110 ° C. Preferably, the homogeneous copolymer has a Tm peak of about 80 to 100 ° C at the DSC. As used herein, the term "substantially a single melting point" means that at least about 80% by weight of the material corresponds to a single Tm peak at a temperature in the range of about 60 to about 110 ° C and essentially no significant fraction of the material shows a melting peak above about 115 ° C, when determined by DSC. DSC measurements are performed on a Perkin Elmer 7 Thermal Analysis System. The melting information given is for the second melt data such that the sample is heated at a programmed rate of 10 ° C / minute to a temperature below its critical range. The sample is then reheated (second melt) at a programmed rate of 10 ° C / minute. The presence of higher melting peaks adversely affects film properties such as haze and reduces the possibility of significantly lowering the heat-sealing initiation temperature of the final film.

The HMW component of the composition of the invention is characterized by an inverse comonomer distribution, preferably the inverse comonomer distribution is characterized by a comonomer distribution gradient ranging from 0.0001 to 0.1 or from 0.0005 to 0.05 and also from 0.001 to 0.02 .

Preferably, the Mw / Mn of the composition is 25 or less, and more preferably in the range of from 5 to 20.

Methods for making homogeneous polymers are disclosed in US Patent Nos. 5,206,075 and 5,241,031 and in PCT International Application No. WO 93/03093. Additional details regarding the preparation and use of one type of homogeneous ethylene-olefin copolymers are disclosed in US Patent No. 5,206,075 to Hodgson Jr .; in U.S. Patent No. 5,241,031 to Mehta; in International PCT Application No. WO 93/03093 on behalf of Exxon Chemical Company and in International PCT Application No. WO 90/03414 on behalf of Exxon Chemical Patents, Inc. Yet another type of homogeneous ethylene / α-olefin copolymers are disclosed in U.S. Patent No. 5,272,236 to Lai et al, and U.S. Patent No. 5,278,272 to Lai et al.

Homogeneously branched linear ethylene / α-olefin interpolymers can also be made by polymerization methods (e.g., disclosed by Elston in US Patent No. 3,645,992) that achieve homogeneous short chain branching distribution. In this method of polymerization, Elston

The plant uses soluble vanadium catalyst systems to prepare such polymers. However, others, e.g., Mitsui Petrochemical Company and Exxon Chemical Company, have used so-called single site catalyst systems to produce polymers with a homogeneous linear structure. U.S. Patent No. 4,937,299 to Ewen et al. And U.S. Patent No. 5,218,071 to Tsutsui et al. Disclose the use of hafnium-based catalyst systems to make homogeneous linear ethylene polymers. Homogeneous linear ethylene / α-olefin interpolymers are currently available from Mitsui Petrochemical Company under the trade name "Tafmer" and from Exxon Chemical Company under the trade name "Exact".

Substantially linear ethylene / α-olefin interpolymers are available from The Dow Chemical Company as AFFINITY ™ polyolefin plastomers. Substantially linear ethylene / α-olefin interpolymers can be made by the methods disclosed in US Patent Nos. 5,272,236, 5,278,272, and 5,665,800.

Other suitable homogeneous ethylene / α-olefin copolymers include ultra-low molecular weight polymers prepared as described in US Patent No. 6,054,544.

In still other embodiments, the HMW ethylene interpolymer component has an inverse comonomer distribution such that greater amounts of comonomer in the interpolymer component are incorporated into the high molecular weight fractions of the interpolymer component. That is, the polymer fractions having an M w greater than or equal to the average M w of the interpolymer component have a higher weight average comonomer amount than the polymer fractions having an M w less than the average M w of the interpolymer component. For example, in some embodiments, the total molar comonomer content of all polymer fractions with an M w greater than or equal to 300,000 g / mole will be at least 25% greater, more preferably at least 30% greater than the molar comonomer content of the polymer fractions with an M w less than or equal to 100,000. g / mol.

The inverse comonomer distribution can be quantified as follows. With regard to the ethylene copolymer component, when, in the cross fractionation chromatography (CFC) of the ethylene copolymer, with respect to extraction at an arbitrary temperature T (° C) falling between the first temperature at which the maximum degree of extraction occurs and the second the temperature which is the lower of the temperatures 10 ° C higher than the first temperature 96 ° C, the relationship between the arbitrarily adopted temperature T (° C) and the point for molecular weight on the molecular weight distribution profile of the copolymer fraction extracted at any adopted temperature T (° C), at which point for the molecular weight on the molecular weight distribution profile of the copolymer fraction there is a peak with maximum intensity, treated with the least squares method, to obtain an approximately straight line between the first temperature and the second temperature; if there is a copolymer fraction of less than 1% by weight of the total amount, excluding the cleaning amount, of the copolymer fraction extracted at temperatures throughout the CFC extraction temperature range, the copolymer fraction can be excluded for an approximating straight line; the approximating straight line has a gradient within the range defined by the formula (I):

-1 {logMp (T¹) -logMp (T²)} / (T¹-T²) -0.005 (I) where:

T.¹ and T.² represents two different arbitrarily assumed extraction temperatures T (° C) in the range between the first temperature and the second temperature, a

2 1 2

Mp (T¹) and Mp (T²) denote respectively the molecular weights corresponding to T.¹ and T.² on an approximating straight line.

2 1 2

In the above formula (I), the expression {logMp (T¹) -logMp (T²)} / (T¹-T²) is the gradient of the above-mentioned approximating straight line.

In some embodiments, cross-fractionation chromatography (CFC) is performed using a CFC T-150A apparatus (manufactured and sold by Mitsubishi Kagaku Corp., Japan). The CFC measurement is performed as follows: a 20 mg sample is dissolved in 20 ml of dichlorobenzene at 140 ° C to obtain a sample solution. Then 5 ml of the resulting solution is added to a TREF column (for temperature-elevated elution fractionation) filled with glass beads, and the solution is cooled to 0 ° C at a rate of 1 ° C / minute. The solution is then heated so as to raise the temperature of the solution at a rate of 1 ° C / min, thereby extracting the copolymer fraction. The extracted copolymer fractions were then subjected to gel permeation chromatography (GPC) using the GPC Shodex AD806MS column (manufactured and sold by Showa Denko KK, Japan) followed by Fourier transform infrared spectroscopy

(FT-IR) using a Nicolet Magna 550 IR spectrometer (manufactured and sold by Nicolet Co., Ltd., USA).

For conventional ethylene copolymers prepared with conventional Ziegler catalysts, the gradient {logMp (T¹) -logMp (T²)} / (T¹-T²) is usually positive. For conventional ethylene copolymers, obtained with conventional metallocene catalysts which have recently been put into practice, the gradient {logMp (T¹) -logMp (T²)} / (T¹-T²) is close to 0, so that the comonomer distribution is substantially homogeneous.

The ethylene copolymer component in some embodiments of the invention exhibits a gradient [{logMp (T¹) -logMp (T²)} / (T¹-T²)] with a relatively large negative value (range from -0.005 to -1). This means that there is an inverse comonomer distribution in the copolymer. In other words, in the ethylene copolymer component, the copolymer fraction with the higher comonomer content has a high molecular weight, in contrast to the conventional ethylene copolymers where the copolymer fraction with the high comonomer content is generally low molecular weight.

In some embodiments, the gradient should preferably be in the ranges:

-0.5 logMp (T¹) -logMp (T²)} / (T¹-T²) -0,007;

or

-0.1 {logMp (T¹) -logMp (T²)} / (T¹- T.²) -0,01;

or

-0.08 {logMp (T¹) -logMp (T²)} / (T¹-T²) -0,02;

2 1 2 where T.¹, T², Mp (T¹) and Mp (T²) are as defined in formula (I).

In other embodiments, with respect to the ethylene copolymer component, the amounts of such copolymer fractions extracted at temperatures at least 10 ° C lower than the first temperature defined above are relatively small. In particular, when the ethylene copolymer component is analyzed by CFC, the ethylene copolymer exhibits characteristics such that the sum of the respective amounts of copolymer fractions extracted at temperatures at least 10 ° C lower than the first temperature defined above is 8 wt% or less. preferably 5% by weight or less, more preferably 3.5% by weight or less, based on the total amount of copolymer fraction extracted at temperatures over the entire range of CFC extraction temperatures but excluding cleaning amounts.

In some embodiments, certain fractions of the ethylene copolymer component satisfy the following relationship (II):

log (Mt) -log (Mc) = 0.5 (II) where Mt is the molecular weight point on the molecular weight distribution profile where the profile exhibits its maximum intensity peak and Mc is any selected molecular weight point on the molecular weight distribution profile .

A molecular weight distribution profile is obtained together with a comonomer content distribution profile by subjecting the ethylene copolymer to gel permeation chromatography-Fourier transform infrared spectroscopy (GPC / FT-IR). An approximate straight line is obtained from the comonomer content distribution profile by the least squares method. The line has a gradient (hereinafter "comonomer distribution gradient") defined by formula (III):

{C (Mc¹) -C (Mc²)} / (logMc¹-logMc²) (III) in which:

Mc¹ and Mc² represent two different and arbitrarily chosen points (Mc) of molecular weight, satisfying the relation (II), a

2 1 2

C (Mc¹) and C (Mc²) respectively represent the comonomer contents corresponding to Mc¹ and Mc² on an approximating straight line.

The comonomer distribution gradient as defined by Formula (III) may range from about 0.0001 to about 0.1, from about 0.0005 to about 0.05, or from about 0.001 to about 0.02, although other values ​​than those ranges are also possible.

As mentioned above, the molecular weight distribution profile and comonomer content distribution profile can be obtained by subjecting the ethylene copolymer to gel permeation chromatography / Fourier transform infrared spectroscopy (GPC / FT-IR). For example, GPC measurements are made using an ALC / GPC 150C apparatus (manufactured and sold by Waters Assoc. Co. USA.) Which uses 3 columns [one Shodex At-807S (manufactured

PL 203 864 B1 and sold by Showa Denko KK, Japan) and two GMH-H6 columns with TSK gel (manufactured and sold by Tosoh Corp., Japan)], connected in series, and FT-IR measurements are performed by dissolving a 20- 30 mg in 15 ml of trichlorobenzene at 140 ° C and introducing 500-1000 µl of the resulting solution into an FT-IR apparatus (PERKIN-ELMER 1760X, manufactured and sold by Perkin Elmer Cetus, Co., Ltd., USA).

Here, "comonomer content" is defined as the value obtained by dividing the number of comonomer units per 1,000 methylene units in the copolymer by 1,000. For example, if 5 copolymer units per 1,000 methylene units are present, the comonomer content is 0.005. The amount of comonomer content can be obtained from the ratio of the absorbance intensity assigned to the comonomer mers to the absorbance intensity assigned to the methylene units, the ratio being determined by FT-IR. For example, when a linear alpha-olefin is used as a comonomer, the ratio of the absorbance intensity at 2960 cm is determined by FT-IR.^-1, assigned to methyl groups, to the absorbance intensity at 2925 cm^-1assigned to methylene groups. The comonomer content can be obtained from the resulting ratio. Characterization of the inverse comonomer distribution and the cross fractionation technique are described in more detail in WO 97/43323.

The new composition can be prepared in a variety of ways. For example, it may be obtained by blending or homogenizing the LMW high density ethylene homopolymer component and the HMW ethylene copolymer component. Alternatively, it may be prepared in more than one polymerization reactor, preferably in a multiple slurry polymerization reactor system.

In some embodiments, the composition is prepared using at least one metallocene catalyst system, alone or in combination with another metallocene catalyst or a Ziegler-Natta catalyst. Preferably, to obtain the HMW component having an inverse comonomer distribution, the metallocene or single site catalyst system is a constrained geometry catalyst system as described in WO 96/16092 WO 98/27119 and WO 96/28480. In a preferred embodiment of the invention, the new composition is prepared using a plurality of reactors connected in series or in parallel, with the metallocene catalyst being introduced into each reactor separately or only into the first reactor. In another preferred embodiment the same metallocene catalyst system is fed to two independently controlled continuously stirred autoclave (CSTR) reactors arranged in series.

Preferably, the single site or metallocene catalyst is supported on an inert material such as silica. More preferably, even when using scavengers, the single site or metallocene catalyst is reacted with a suitable cocatalyst (e.g. boron-containing compound or alumoxane) that has been linked or bound to the support in the previous step, such that the single-site or metallocene catalyst is immobilized to such an extent that during polymerization there is essentially no extraction of the soluble catalyst components from the support, and most preferably the components are combined or bound so that substantially no extraction occurs when the solid catalyst system is refluxed in toluene for 2 hours. Suitable single site catalyst systems for use in preparing the novel composition are described in detail in US Patent Nos. 6,043,180 and 5,834,393.

While any known polymerization method is believed to be suitable for use in preparing the composition, preferably the novel composition is made by a particulate polymerization process (i.e., a slurry or gas phase process), more preferably a slurry polymerization process, and most preferably a a loop or slurry autoclave (CSTR) polymerization process in at least two reactors operating sequentially (i.e. in series). In particular, a polymerization system with two reactors connected in series is used. In a preferred embodiment of the invention, the serial polymerization is carried out such that fresh catalyst is injected separately into each reactor. Preferably, when the catalyst is injected into each reactor separately, no (or essentially no) living polymer or active catalyst is introduced from the first reactor into the second reactor, since polymerization in the second reactor is only achieved by injecting fresh catalyst and monomer into it ( and comonomer).

In another preferred embodiment, the composition is prepared using a plurality of reactors (preferably a two-reactor system) in series, with fresh catalyst in the form of a supported catalytic system only being injected into the first reactor.

It is such that the living polymer and / or catalyst components are led from the first reactor to the next reactor to effect polymerization with fresh monomer and optionally comonomer.

Most preferably, whether separate injection into each reactor or injection into the first reactor is used, the resulting composition is characterized in that it comprises constituent polymers with different unimodal molecular weight distributions.

In the case of multi-reactor polymerization, a pressure control device (stripper, extrusion valve and / or pump) may be used on the stream flowing between the successive reactors. The above methods are disclosed in US Provisional Patent Application No. 60/313176, filed August 17, 2001, entitled "Particle-Form Ethylene Polymerization Process," on behalf of Ruddy AJ Nicasy et al.

In series run polymerization, the high density LMW component or HMW interpolymer component may be prepared in the first reactor. For process control reasons, however, the HMW component is preferably produced in the first reactor.

In addition to the serial polymerization, the novel composition can also be prepared from single-pot or multi-reactor constituent polymers using dry, tumble or extruder mixing techniques.

The HMW interpolymer component comprises ethylene and at least one olefin, preferably

C.₃-C₂₀ α-olefin or C.₄-C₁₈ diolefin. Suitable comonomers include, but are not limited to, C.₃-C₂₀ α-olefins such as propylene, isobutylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, and 1-decene. In some embodiments, the HMW interpolymer component is an ethylene and 1-butene copolymer. Chain transfer agents can be used in the polymerization.

Density is measured according to ASTM D-792. Melt index measurements are made according to ASTM D-1238, 190 ° C / 2.16 kilogram (kg) condition and 190 ° C / 5 kg (kg) condition, known as I2 and I5, respectively. The melt index is inversely proportional to the molecular weight of the polymer. Accordingly, the higher the molecular weight, the lower the melt index, although the relationship is not linear. The melt index is given in g / 10 minutes. Melt index determinations can also be made under even higher loads, e.g. according to ASTM D-1238, 190 ° C / 10 kg condition and 190 ° C / 21.6 kg condition, known as I10 and I21.6 respectively.

In this specification, the term "melt flow ratio" is used in the usual sense to mean the ratio of the melt flow rate determined at higher load to that determined at lower load. In the case of measuring I10 and I2 melt index values, the melt flow ratio is usually denoted as I10 / I2. For the values ​​of I21.6 and I10, the ratio is determined as I21.6 / I10.

Gel Permeation Chromatography (GPC) data was recorded on a Waters 150C / ALC, Polymer Laboratories Model PL-210 or Polymer Laboratories Model PL-220. The column and carousel compartments were kept at 140 ° C. The columns used were 3 Polymer Laboratories 10 micron Mixed-B columns. The samples were prepared at a concentration of 0.1 g of polymer in 50 ml of 1,2,4-trichlorobenzene. 1,2,4-trichlorobenzene used in the preparation of the samples contained 200 ppm of butylated hydroxytoluene (BHT). Samples were prepared by agitating gently for 2 hours at 160 ° C. The injection volume was 100 µl and the flow rate was 1.0 ml / minute. GPC calibration was performed using narrow molecular weight distribution polystyrene standards purchased from Polymer Laboratories. The resulting reference molecular weight peaks for polystyrene were converted to polyethylene molecular weights using the following equation (given in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968):

^M.polyethylene ^{= A x (M}polystyrene⁾ where M is the molecular weight, A is 0.4316 and B is 1.0. Molecular weight calculations were performed using Viscotek TriSEC software.

The GPC data was then deconvolved to achieve the most likely match of the molecular weights of the two components. There are a number of deconvolution algorithms available both commercially and in the literature. They can lead to different answers depending on the assumption made. The algorithm presented here is optimized for the deconvolution problem of the two most likely molecular weight distributions (plus the adjustable error term). In order to take into account changes in the relevant distributions due to macromer incorporation and small fluctuations in the conditions in the reactor (temperature, concentration),

The basic functions were modified by introducing the component of the normal distribution. This component enables the essential function for each component to be "smeared" along the molecular weight axis. The advantage of this procedure is that under boundary conditions (low LCB, ideal concentration and temperature control), the fundamental function will take the form of a simple, most probable Flory distribution.

Three components (j = 1, 2, 3) are derived, with the third component (j = 3) being the adjustable error component. GPC data must be normalized and correctly converted into weight fractions as a function of log10 molecular weight vectors. In other words, any potential deconvolution curve should contain a height vector, hi, where heights are reported at known log10 molecular weight intervals, where hi has been correctly converted from elution volume domain to log10 molecular weight domain and hi values ​​are normalized. Additionally, this data should be available for the EXCEL ™ application.

In order to perform deconvolution, several assumptions are made. Each term, j, relates to the most probable Flory distribution, which has been entwined with a normal or Gaussian scatter function using the parameter, µj. The obtained three basic functions were used in the Chi-square, μ minimization routine², to locate the parameters which best match the n points in hi, the GPC data vector.

X²(paj, Wj) = Σ | [[2 = 1 Wj · M² [· CumNDjk · e^M. ^ LogwM - hi] k-10 μ + - σ.

λ = 10 ' ^{3 j}

The variable CumNDj, k is calculated using the EXCEL ™ "NORMDIST (x, mean, standard_dev, cumulative)" function with the following parameter settings:

x = μ + (k-10) μμ / 3 mean = μ standard dev = μ cumulative = TRUE

Table 1 below summarizes these variables and their definitions.

The use of Microsoft EXCEL ™, Solver software is appropriate for this task. Constraints are added to Solver to ensure proper minimization.

Table 1: Definitions of variables

<td>Name variable</td><td>Definition</td>

<td>Mj, k</td><td>Reciprocal value of the number average molecular weight of the most probable (Flory) distribution for component j, range of the normal distribution k</td>

<td>Mj</td><td>Sigma (square root of the variance) for the normal (Gaussian) scatter function for component j</td>

<td>Ex</td><td>Weight fraction of component j</td>

<td>K.</td><td>The normalization component (1.0 / log_e10)</td>

<td>To me</td><td>Molecular weight over the interval and elution volume</td>

<td>hi</td><td>The height of the logio (molecular weight) graph in the interval i</td>

<td>n</td><td>The number of bins in the log (molecular weight) graph</td>

<td>and</td><td>Log interval index (molecular weight) (1 to n)</td>

<td>j</td><td>Ingredient indicator (1 to 3)</td>

<td>1 k</td><td>Normal distribution interval indicator</td>

<td>Logio M.</td><td>The mean difference between log10Mi and log10Mi-1 in the plot of height versus log10M</td>

The parameters obtained as a result of Chi-square minimization are μ1, μ2, μμ3, μ1, μ2, μμ3, w1 and w2. The value of w3 is then derived from w1 and w2 as the sum of the 3 terms must be 1. Table 2 summarizes the Solver constraints used in EXCEL.

Table 2: List of limitations

<td>Description</td><td>Limit</td>

<td>Maximum fraction 1</td><td>w1 &lt;0.95 (user settable)</td>

<td>Lower limit of the scatter function</td><td>μ1, μμ2, μμ₃ &gt; 0.001 (must be positive)</td>

<td>Upper limit of the scatter function</td><td>μ1, μμ2, μμ3 (user adjustable)</td>

<td>Normalized fractions</td><td>in₁ + in₂ + in₃ = 1,0</td>

Additional constraints to consider are the limitation that only μj&gt; 0 is allowed, although if the solver is properly initialized, this restriction need not be introduced as the solver routine will not move any of μ to less than about 0.005. You should also be aware that all wj are positive. This limitation can be made without using Solver. When it is considered that wj is derived from selecting two points in the range 0.0 &lt;P1 &lt;P2 &lt;1.0; where w1 = P1, w2 = P2 - P1 and w3 = 1.0 - P2; then the constraints P1 and P2 are equivalent to the constraints required for wj above.

Table 3 lists the Solver settings in the Options tab.

Table 3: Solver Settings

<td>Marker</td><td>Value or choice</td>

<td>Max Time (s)</td><td> 1000</td>

<td>Iterations</td><td> 100</td>

<td>Precision</td><td> 0,000001</td>

<td>Tolerance (%)</td><td> 5</td>

<td>Convergence</td><td> 0,001</td>

<td>Estimates</td><td>Tangent</td>

<td>Derivatives</td><td>Forward</td>

<td>Search</td><td>Newton</td>

<td>All other choices</td><td>Not chosen</td>

A first estimate for μ1, μ2, w1, and w2 can be obtained by assuming two ideal Flory components representing the observed weight average, number average and z-average molecular weight for the observed GPC distribution.

n, GPC w, GPC w, GPC ₌ [w1 ₌ [w1

1 Ί^-1

- + in₂-10^μ1 ² 10^μ2 ·10^μ + in₂ 2 ·10^μ2 ] / MnGPC · 10^μ + in₂ · 6 ·10^μ2 ] /^M.w, GPC w1 + w2 = 1

The values ​​for μ1, μ2, w1, and w2 are then calculated. Adjust them carefully to achieve the small error term, w3, and to meet the constraints in Table 2 before entering the Solver to perform the minimize step. All initial μj values ​​are set to 0.05.

Preparative GPC to collect selected polymer fractions was performed with a Waters 150C / ALC apparatus equipped with preparative pump heads, modified with a 3000 μl injection loop, with 14 ml sample vials. The column and carousel compartments were kept at 140 ° C. 1 Jordi Associaties 5μ column with divinylbenzene was used as preparative GPC column

No. 15105 (DVB), catalog no. 15105. The column length was 500 mm and the internal diameter was 22 mm. 1,2,4-trichlorobenzene was used both for sample preparation and as the mobile phase in chromatography. The samples were prepared at a concentration of 0.1 g of polymer in 50 ml of solvent. The solvent used in the preparation of the samples contained 200 ppm of butylated hydroxytoluene (BHT). Samples were prepared by agitating gently for 2 hours at 160 ° C. The injection volume was 2500 µl and the flow rate was 5.0 ml / minute.

Approximately 200-300 injections were made to collect sufficient samples for off-instrument analysis. 16 fractions were collected over the entire elution range of the column with typically 8-12 fractions covering the elution range of the sample. The scope of the elution was verified on the basis of the analysis of the refractive index during start-up. The collected solvent fractions were evaporated to a volume of about 50-60 ml in a Buchi Rotovapor R-205 evaporator equipped with a V-805 vacuum regulator module and a B-409 heating bath module. The fractions were then allowed to cool to room temperature and the polyethylene was precipitated by adding about 200 ml of methanol. The molecular weight fractionation was confirmed by high temperature GPC analysis with refractive index detection. The typical polydispersity of the fractions, measured by GPC analysis, was around 1.1 - 1.4.

The weight average branching index for the selected fractions was obtained from the direct determination of the intrinsic viscosity and molecular weight for each section of the chromatographic data. The chromatographic system used was Polymer Laboratories Model PL-210 or Polymer Laboratories Model PL-220, equipped with a Viscotek Model 210R differential viscometer and a Precision Detectors Model 2040 2-angle laser light scattering detector. The detected 15 ° light scattering was used to calculate the molecular weights.

The column and carousel compartments were kept at 140 ° C. The columns used were 3 Polymer Laboratories 10-micron Mixed-B columns. 1,2,4-trichlorobenzene was used as a solvent. The samples were prepared at a concentration of 0.1 g of polymer in 50 ml of solvent. The solvent used in the preparation of the samples contained 200 ppm of butylated hydroxytoluene (BHT). Samples were prepared by agitating gently for 2 hours at 160 ° C. The injection volume was 100 μί and the flow rate was 1.0 ml / minute.

Calibration of the GPC column was performed using narrow molecular weight distribution polystyrene standards purchased from Polymer Laboratories. The calibrations of the detectors were performed in a manner detectable for NBS 1475, using a linear polyethylene homopolymer.¹³C NMR was used to confirm the linearity and composition of the homopolymer standard. The refractometer was calibrated for weight verification based on the known concentration and injection volume. The viscometer was calibrated with NBS 1475 at 1.01 dl / g and the light scattering detector was calibrated with NBS 1475 using a molecular weight of 52,000 daltons.

A systematic approach to determining multi-detector shifts was performed in a manner consistent with Mourey and Balke, Chromatography of Polymers: T. Provder, ed .; ACS Symposium Series 521; American Chemical Society: Washington, DC, (1993) pp. 180-198, and Balke et al; T. Provder, Ed .; ACS Symposium Series 521; American Chemical Society: Washington, DC, (1993): pp. 199-219, both of which are incorporated by reference in their entirety. The results obtained with the triple detector were compared using the NBS 706 polystyrene standard material (National Bureau of Standards) or the DOW Chemical 1683 polystyrene resin to calibrate the column with polystyrene to obtain a calibration curve for the standards in the form of narrow fractions of polystyrene.

The verification of the alignment and calibration of the detectors was made based on the analysis of a linear polyethylene homopolymer with a polydispersity of about 3 and a molecular weight of 115,000. The verified value of the Mark-Houwink plot slope for the linear homopolymer was in the range of 0.725 - 0.730 in the area of ​​molecular weights 30,000 - 600,000. at least 3 injections for reliability. The molecular weights corresponding to the peaks for the polystyrene standards were converted to the molecular weights of the polyethylene by the method of Williams and Ward previously described. The verified compatibility of Mw and Mn between the polystyrene calibration method and the absolute triple detector method is within 5% for the polyethylene homopolymer.

Cross-fractionation chromatography (CFC) is performed with a CFC T-150A apparatus (manufactured and sold by Mitsubishi Kagaku Corp., Japan) as follows: A sample of 20 mg is dissolved in 20 ml of dichlorobenzene at 140 ° C to

To obtain a sample solution. Then 5 ml of the resulting solution is added to a TREF column (for temperature-elevated elution fractionation) filled with glass beads, and the solution is cooled to 0 ° C at a rate of 1 ° C / minute. The solution is then heated so as to raise the temperature of the solution at a rate of 1 ° C / min, thereby extracting the copolymer fraction. The extracted copolymer fractions were then subjected to gel permeation chromatography (GPC) using the GPC Shodex AD806MS column (manufactured and sold by Showa Denko KK, Japan), followed by Fourier transform infrared spectroscopy (FT-IR) with a Nicolet Magna 550 IR spectrometer (manufactured and sold by Nicolet Co., Ltd., USA.). More details on CFC analysis can be found in the catalog attached to the above mentioned CFC T-150A apparatus. Tensile properties were measured according to ASTM D 638-76.

The invention also includes the use of a composition of the invention for the manufacture of an article selected from the group consisting of pipe, film, fiber, blow molded article, injection molded, extrusion or rotomoulded article, extrusion coating, and extrusion blow molded articles.

The novel composition is particularly suitable for the manufacture of blow molded articles (especially tall, top-fill) and water and gas transmission or distribution pipes, especially pipes substantially superior to PE100 performance. In other words, the new composition allows you to increase the service life of the pipes. U.S. Patent Nos. 6,204,349, 6,191,227, 5,908,679, 5,683,767, 5,417,561, and 5,290,498 disclose various pipes and methods of making pipes that may be used in embodiments of the invention.

Many useful articles can be made from the disclosed novel compositions. For example, molding processes, including various injection molding processes, may be useful in making useful articles or parts from the disclosed compositions (e.g. described in Modern Plastics Encyclopedia / 89, Mid-October 1988 Edition, Vol. 65, No. 11, p. 264). -268, "Introduction to Injection Molding," H. Randall Parker, and pp. 270-271, "Injection Molding Thermoplastics," Michael W. Green and Blow Molding Processes (described, e.g., in Modern Plastics Encyclopedia / '89, Mid-October 1988 Edition, Vol. 65, No. 11, pp. 217-218, "Extrusion-Blow Molding", Christopher Irwin, Profile Extrusion , calendering, pultrusion (e.g. of pipes), etc. Also for rotationally molded articles, the described novel compositions may have advantages. Rotational molding techniques are well known to those skilled in the art and include e.g. techniques described in Modern Plastics Encyclopedia / '89, Mid-October 1988 Edition, Vol. 65, No. 11, pp. 296-301, "Rotational Molding", RL Fair.

Fibers (e.g., staple fibers, meltblown fibers, or spunbonded filaments (e.g., using the systems disclosed in U.S. Patent Nos. 4,340,563, 4,663,220, 4,668,566, or 4,322,027), gel-spun fibers can also be made from the disclosed novel compositions. the "gel spun" type (e.g., using the systems disclosed in U.S. Patent No. 4,413,110), woven and non-woven materials (e.g. hydronins disclosed in U.S. Patent No. 3,485,706) or structures made of such fibers (including, for example, blends of such fibers with other fibers, e.g., PET or cotton).

Films and film structures can also be produced from the described novel compositions using known hot-blown film-making techniques or other biaxial orientation processes, such as tenter frame processes or double-bladder processes. Conventional hot-blown film processes are described, e.g., in The Encyclopedia of Chemical Technology, Kirk-Othmer, 3rd edition, John Wiley &amp; Sons, New York, 1981, Vol. 16, pp. 416-417 and Vol. 18, pp. 191-192. . A method for producing a biaxially oriented film such as the "double bladder" method described in U.S. Patent No. 3,456,044 (Pahlke) and the methods disclosed in U.S. Patent Nos. 4,352,849 (Mueller), 4597920 (Golike), 4,820,557 (Warren), 4,837,084 (Warren ), 4,865,902 (Golike et al.), 4,927,708 (Herran et al.), 4,952,451 (Mueller), 4,963,419 (Lustig et al.), And 5,059,481 (Lustig et al.), Can also be used to produce foil structures from the described novel compositions. Film structures can also be produced by a tenter frame method, such as that used with oriented polypropylene.

Other methods of making multilayer films for use in food packaging are described in Packaging Foods With Plastics, Wilmer A. Jenkins and James P. Harrington (1991), pp. 19-27 and in "Coextrusion Basics" by Thomas I. Butler, Film Extrusion Manual: Process. , Materials, Properties, pp. 31-80 (TAPPI Press (1992)).

The films can be single-layer or multi-layer. The film produced from the new compositions may be coextruded with another layer (s), or the film may be laminated onto another layer (s).

In separate operations such as those described in Packaging Foods With Plastics, Wilmer A. Jenkins and James P. Harrington (1991) or in "Coextrusion For Barrier Packaging", WJ Schrenk and CR Finch, Society of Plastics Engineers RETEC Proceedings, June 15-17 (1981), pp. 211-229. When monolayer film is produced by sleeve extrusion (i.e. the blown film method) or through a flat die (i.e. cast film) as described by KR Osborn and WA Jenkins in "Plastic Films, Technology and Packaging Applications" (Technomic Publishing Co., Inc. (1992)), then the film must be subjected to additional gluing or extrusion lamination after extrusion with other layers of the packaging material to obtain a multilayer structure. When two or more layers of film are coextruded (as also described by Osborn and Jenkins), the film can still be laminated with additional layers of packaging materials depending on other physical requirements of the finished film. In the publication "Laminations Vs. Coextrusion ”by D. Dumbleton (Converting Magazine (September 1992)) also compared lamination with coextrusion. Monolayer and coextruded films can also be subjected to other treatments after extrusion, such as biaxial orientation.

Extrusion coating is another technique for producing multilayer film structures using the novel compositions described herein. The new compositions comprise at least one layer of the foil structure. As with cast films, extrusion coating is a flat die technique. The sealing material can be used for extrusion coating the substrate as a single layer or as a coextruded article.

Typically, in the case of a multi-layer film structure, the described novel compositions comprise at least one layer throughout the multi-layer film structure. Other layers of the multi-layer structure include, but are not limited to, barrier layers, and / or tie layers, and / or structural layers. Various materials can be used in these layers, some of which are used in more than one layer of the same film structure. Some such materials include: film, nylon, ethylene / vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), oriented polypropylene (OPP), ethylene / vinyl acetate (EVA) copolymers, ethylene / acid copolymers acrylic (EAA), ethylene / methacrylic acid copolymers (EMAA), LLDPE, HDPE, LDPE, nylon, graft adhesive polymers (e.g. maleic anhydride grafted polyethylene), and paper. Typically, multilayer film structures contain from 2 to about 7 layers.

Examples

The following examples are provided to illustrate various embodiments of the invention. They are not to be considered representative of all embodiments of the invention and do not limit the scope of the claimed invention as described herein. All figures provided are approximate values ​​and may vary within their accuracy ranges.

The polymer of Example 1 was prepared using a supported, constrained borate catalyst system in a small, continuously stirred, slurry polymerization experimental plant (autoclave) containing two reactors connected in series. The immobilized solid catalyst system was prepared as follows: silica gel (grade 948, available from Grace-Davidson) was dehydrated at elevated temperature to a total volatiles content of about 3% by weight. 24.71 kg of the obtained silica was suspended in 130 liters of dry hexane, then 30.88 kg of 1.21 M solution of triethylaluminum (TEA) in hexane were added. The slurry was filtered and washed with fresh, dry hexane (130 liters per wash) at ambient temperature until the residual aluminum content of the wash was &lt;0.5 mmol / liter. The solid was then filtered off and dried under vacuum (~ 13.33 × 10² Bye; ~ 10 torr) at 60 ° C to a residual solvent level of 1.0 wt% or less. 1.5 mol [NHMe (C18-22H37-45) 2] ^ [HOC6H4B (C6F5) 3] as 16.95 kg of a 10.1 wt% solution in toluene was diluted by adding 9.61 liters (8.32 kg) toluene. This solution was stirred for 10 minutes, then 1.65 mol of TEA, as 0.88 liter (0.76 kg) of a 1.87M solution of TEA in toluene, was added and the resulting solution was stirred for 15 minutes. The solid silica / TEA component was then added over approximately 30 minutes. After the addition was complete, the impregnated material was mixed for 60 minutes. With continued agitation, 195 liters (128.7 kg) of dry, fresh hexane at ambient temperature was added to the solid component and the resulting slurry was stirred for 30 minutes. Subsequently 1.2 moles of constrained structure catalyst, (η⁴-1,3-pentadiene) (C5Me₄SiMe₂NtBu) Ti (as 3.69 kg 0.223 M heptane solution) and the suspension was stirred for 2 hours. The solvent was removed from the slurry by filtration and the resulting solid was washed 4 times with dry,

With fresh hexane at ambient temperature and dried in vacuo to give a free flowing powder.

This supported, constrained borate catalyst system was then charged to the bomb and into the catalyst feed vessels of the reactor system, from which fresh catalyst was injected separately into each reactor. In these vessels, the supported catalyst system was further diluted with dry fresh hexane.

The small experimental setup consisted of two 10 liter slurry reactors operated at a liquid fill ratio of about 70 vol%, the contents mixed at 1000 rpm with a Lightnin A310 mixing paddle. The temperature of the reactor was kept constant by the cooling jacket, the melt flow rate was controlled by the amount of hydrogen feed, and the density was controlled by the amount of comonomer added, with 1-butene being used as comonomer in all cases. All feed streams were introduced via submerged tubing into the liquid phase to ensure thorough mixing. Hexane was used as a diluent.

The polymer of Example 1 was prepared by melt blending two substantially equivalent batches from the experimental reactors, Example 1A and Example 1B. The melt-blending of the two small batches was necessary to obtain sufficient polymer for testing and manufacturing the articles. The conditions under which the batches of Example 1A and Example 1B were performed are set out in Table 4a and Table 4b. The first reactor was operated at 65 ° C with an ethylene flow rate of 900 g / hour (reacted), a hydrogen flow rate of 3.55 N-liters / hour, and a hexane flow rate of 2500 g / hour. In order to maintain a constant pressure of 12 bar, 30 µmol / hour of Ti was added. In any case, no unbound cocatalyst was added to avoid fouling of the reactor, and no comonomer (or a trace amount of it was added) was added to obtain high density polyethylene in the first stirred tank reactor for slurry polymerization.

The entire contents of the first reactor were continuously transferred to a second stirred slurry tank reactor which was operated at 75 ° C with new feeds fed: 750 g / h of ethylene (reacted), with no hydrogen stream and 15 g / h. hour of 1-butene in 2500 g / hour of hexane. The second reactor was operated at a slightly lower pressure 11d0²kPa (11 bar) to allow transfer from the first to the second reactor. Part of the gas phase from the second reactor was degassed to control the hydrogen concentration in the liquid phase. Additional catalyst stream was fed to the second reactor to make the relative amount produced in the first reactor 48.3% and in the second reactor 51.7%. The relative amount produced in the reactor is referred to herein as "split" and is expressed as a percentage or as a fraction.

In the case of selected trials, the gas phases in both reactors were analyzed and the results of the analysis are given in Table 5. The contents of the second reactor were continuously directed to the stripper tank operating at a pressure of 1.3 × 10² kPa (1.3 bar) at 75 ° C and stripped of diluent, unreacted monomer and comonomer. Stripping gave a dry powder. The yields and properties of the products of Example 1A and Example 1B are shown in Table 6.

The inventive polymer of Example 1 was prepared by melt blending the products of Examples 1A and 1B with 750ppm calcium stearate and 3000ppm Irganox ™ B225 in a LEISTRITZ ZSE 60 counter rotating twin screw extruder. A carbon black masterbatch based on DOWLEX ™ LLDPE 2384 resin was added for mixing, so to obtain a final carbon black concentration of 2.28 wt%. Melt mixing was carried out in a gentle manner as the extruder (65 mm, L / D 24) was operated with a temperature profile of 190-220 ° C with a throughput of 28 kg / hour and a speed of 40 rpm. The inventive polymer of Example 1 was fed to a minimum specific energy and the atmosphere in the powder hopper was adjusted to 1-4% oxygen by purging nitrogen into the feed hopper. The inventive polymer of Example 1 was extruded twice to ensure good homogeneity. The properties of the final product according to the invention of Example 1 can be found in Table 4. Its melt index I5 was 0.27 g / 10 minutes and the density was 0.9668 g / cm 2.³.

As shown in Tables 4-7, the inventive product of Example 2 was prepared in a similar manner to the inventive product of Example 1, except that the inventive product of Example 2 did not require the mixing of two batches to increase the available amounts. The inventive product from Example 2 was stabilized and blended with the carbon black in a similar manner to the inventive product

Of Example 1, where, as shown in Table 7, its melt index was I5 0.20 g / 10 minutes, and the density was 0.9604 g / cm³.

Table 4a - Process conditions in the first reactor

<td>Example</td><td>Reactor temperature, ° C</td><td>Pressure in the reactor kPa</td><td>Flow catalyst (crash bars / h</td><td>Flow cocatalyst g / h</td><td>Flow C2 g / h</td><td>CM ABOUT c ro 5 about N ro CD σ About CD</td><td>CM ABOUT c ro 5 about CD ro &lt;D φ U «c 0- CD</td><td>CM AND S_ Φ U «C 0- CD</td><td>Flow C4 g / h</td><td>Flow C6 g / h</td><td>Speed agitators rpm</td>

<td>1a</td><td> 65</td><td> 12·10²</td><td> 30</td><td>lack</td><td> 900</td><td> 200</td><td> 700</td><td> 3,55</td><td> 0</td><td> 2500</td><td> 1000</td>

<td>1b</td><td> 65</td><td> 12·10²</td><td> 30</td><td>lack</td><td> 800</td><td> 200</td><td> 600</td><td> 3,55</td><td> 0</td><td> 2500</td><td> 1000</td>

<td> 2</td><td> 65</td><td> 12·10²</td><td> 13,55</td><td>lack</td><td> 880</td><td> 200</td><td> 680</td><td> 3,7</td><td> 0</td><td> 2500</td><td> 750</td>

<td>3a</td><td> 65</td><td> 11 ·10²</td><td> 32,8</td><td>lack</td><td> 900</td><td> 200</td><td> 700</td><td> 3,55</td><td> 0</td><td> 2500</td><td> 1000</td>

<td>3b</td><td> 65</td><td> 11 ·10²</td><td> 24</td><td>lack</td><td> 920</td><td> 200</td><td> 720</td><td> 3,55</td><td> 0</td><td> 2500</td><td> 1000</td>

<td>3c</td><td> 65</td><td> 12·10²</td><td> 34</td><td>lack</td><td> 950</td><td> 200</td><td> 750</td><td> 3,55</td><td> 0</td><td> 2500</td><td> 1000</td>

<td>4a</td><td> 65</td><td> 12·10²</td><td> 11,25</td><td>lack</td><td> 962</td><td> 200</td><td> 761,5</td><td> 4,4</td><td> 0</td><td> 2500</td><td> 750</td>

<td>4b</td><td> 65</td><td> 12·10²</td><td> 19,77</td><td>lack</td><td> 846</td><td> 200</td><td> 645,5</td><td> 3,887</td><td> 0</td><td> 2500</td><td> 750</td>

Table 4b - Process conditions in the second reactor

<td>Example</td><td>Temperature reactor, ° C</td><td>Pressure in the reactor kPa</td><td>Flow catalyst crash bars / h</td><td>Flow of cocatalyst g / h</td><td>Flow C2 g / h</td><td>odg Azov C2 g / h</td><td>Overload- valid C2 g / h</td><td>CM AND S_ Φ U «C 0- CD</td><td>Flow C4 g / h</td><td>Flow C6 g / h</td><td>Speed agitators rpm</td>

<td>1a</td><td> 75</td><td> 11 ·10²</td><td> 30</td><td>lack</td><td> 1350</td><td> 600</td><td> 750</td><td> 0</td><td> 15</td><td> 2500</td><td> 1000</td>

<td>1b</td><td> 75</td><td> 11 ·10²</td><td> 30</td><td>lack</td><td> 1400</td><td> 600</td><td> 800</td><td> 0</td><td> 15</td><td> 2500</td><td> 1000</td>

<td> 2</td><td> 65</td><td> 11 ·10²</td><td> 32,8</td><td>lack</td><td> 1075</td><td> 380</td><td> 695</td><td> 0</td><td> 40</td><td> 2500</td><td> 935</td>

<td>3a</td><td> 75</td><td> 11 ·10²</td><td> 32,8</td><td>lack</td><td> 1400</td><td> 600</td><td> 800</td><td> 0</td><td> 15</td><td> 2500</td><td> 1000</td>

<td>3b</td><td> 75</td><td> 11 ·10²</td><td> 24</td><td>lack</td><td> 1380</td><td> 600</td><td> 780</td><td> 0</td><td> 15</td><td> 2500</td><td> 1000</td>

<td>3c</td><td> 75</td><td> 11 ·10²</td><td> 34</td><td>lack</td><td> 1350</td><td> 600</td><td> 750</td><td> 0</td><td> 15</td><td> 2500</td><td> 1000</td>

<td>4a</td><td> 65</td><td> 11 ·10²</td><td> 30</td><td>lack</td><td> 938</td><td> 350</td><td> 588</td><td> 0</td><td> 38</td><td> 2500</td><td> 750</td>

<td>4b</td><td> 65</td><td> 11 ·10²</td><td> 32,8</td><td>lack</td><td> 919</td><td> 380</td><td> 539</td><td> 0</td><td> 37,7</td><td> 2500</td><td> 935</td>

Table 4c - General process conditions

<td>Example</td><td>Temperature in the stripper tank ° C</td><td>Division R1 / R2 % /%</td>

<td>1a</td><td> 75</td><td> 48,3/51,7</td>

<td>1b</td><td> 75</td><td> 42,9/57,1</td>

<td> 2</td><td> 75</td><td> 46,3/53,7</td>

<td>3a</td><td> 75</td><td> 47,4/52,6</td>

<td>3b</td><td> 75</td><td> 48,0/52,0</td>

<td>3c</td><td> 75</td><td> 50,0/50,0</td>

<td>4a</td><td> 75</td><td> 50,5/49,5</td>

<td>4b</td><td> 75</td><td> 52,7/47,3</td>

PL 203 864 B1

TABLE 5 - Gas analysis in the first and second reactors

<td></td><td colspan="6">The first reactor</td><td colspan="6">Second reactor</td>

<td>Example</td><td>Butene mole%</td><td>Nitrogen mole%</td><td>Ethylene mole%</td><td>Hexane mole%</td><td>Hydrogen mole%</td><td>Ethane mole%</td><td>Butene mole%</td><td>Nitrogen mole%</td><td>Ethylene mole%</td><td>Hexane mole%</td><td>Hydrogen mole%</td><td>Ethane mole%</td>

<td> 2</td><td> 0,00</td><td> 1,17</td><td> 94,58</td><td> 1,46</td><td> 1,34</td><td> 0,00</td><td> 0,47</td><td> 0,56</td><td> 95,07</td><td> 1,81</td><td> 0,02</td><td> 0,00</td>

<td>3a</td><td> 0,01</td><td> 1,14</td><td> 90,7</td><td> 3,99</td><td> 1,41</td><td> 0,17</td><td> 0,28</td><td> 0,7</td><td> 93,3</td><td> 2,92</td><td> 0,17</td><td> 0,01</td>

<td>4a</td><td> 0,00</td><td> 0,83</td><td> 92,35</td><td> 3,02</td><td> 1,27</td><td> 0,22</td><td> 0,42</td><td> 0,82</td><td> 91,33</td><td> 4,49</td><td> 0,03</td><td> 0,15</td>

<td>4b</td><td> 0,00</td><td> 1,17</td><td> 95,19</td><td> 1,63</td><td> 1,27</td><td> 0,00</td><td> 0,45</td><td> 0,54</td><td> 95,05</td><td> 2,43</td><td> 0,02</td><td> 0,00</td>

TABLE 6 - Preparation and properties of the product of an example of the invention

<td>For example</td><td>Time of trial hours</td><td>Performance the product kg</td><td>^AND21 g / 10 minutes</td><td>^AND5 g / 10 minutes</td><td>LO CM</td><td>Density g / cm³</td><td>Butene according to FTIR mole%</td><td>Crystallinity according to DSC %</td><td>Q ABOUT or</td>

<td>1a</td><td> 12</td><td> 6,5</td><td> 10</td><td> 0,32</td><td> 31,4</td><td> 0,9576</td><td> 0,475</td><td> 77,76</td><td>Yes</td>

<td>1b</td><td> 6</td><td> 5,5</td><td> 12,6</td><td> 0,41</td><td> 30,7</td><td> 0,9591</td><td> 0,5</td><td> 77,53</td><td>Yes</td>

<td> 2</td><td> 15</td><td> 18</td><td> 4,22</td><td> 0,21</td><td> 20,1</td><td> 0,9501</td><td>NB</td><td> 74</td><td>Yes</td>

<td>3a</td><td> 10</td><td> 5,8</td><td> 8,50</td><td> 0,4</td><td> 21,3</td><td> 0,9554</td><td> 0,55</td><td> 76,35</td><td>Yes</td>

<td>3b</td><td> 12</td><td> 5,5</td><td> 7,75</td><td> 0,3</td><td> 25,2</td><td> 0,9547</td><td> 0,57</td><td> 77,84</td><td>Yes</td>

<td>3c</td><td> 7</td><td> 3,8</td><td> 8,37</td><td> 0,4</td><td> 20,9</td><td> 0,954</td><td> 0,69</td><td> 74,34</td><td>Yes</td>

<td>4a</td><td> 13</td><td> 12</td><td> 9,55</td><td> 0,47</td><td> 20,3</td><td> 0,9518</td><td>NB</td><td> 68,8</td><td>Yes</td>

<td>4b</td><td> 12</td><td> 9</td><td> 8,63</td><td> 0,39</td><td> 22,1</td><td> 0,9504</td><td>NB</td><td>NB</td><td>Yes</td>

NB means "not tested"

TABLE 7 - Properties of the products of the inventive examples and of the comparative trials

<td>Example</td><td>According to the invention 1</td><td>According to the invention 2</td><td>According to the invention 3</td><td>According to the invention 4</td><td>Comparative 1</td><td>Comparative 2</td>

<td>AND₅ g / 10 minutes</td><td> 0,27</td><td> 0,20</td><td> 0,42</td><td> 0,41</td><td> 0,21</td><td> 0,40</td>

<td>AND₁₀ g / 10 minutes</td><td>NB</td><td> 0,69</td><td>NB</td><td> 1,37</td><td> 0,85</td><td>NB</td>

<td>21.6 g / 10 minutes</td><td> 5,28</td><td> 4,36</td><td> 8,75</td><td> 8,14</td><td> 6,21</td><td> 9,39</td>

<td>I21.6 / Is</td><td> 19,6</td><td> 21,8</td><td> 20,8</td><td> 19,9</td><td> 29,6</td><td> 22,7</td>

<td>Density, g / cm³</td><td> 0,9668</td><td> 0,9604</td><td> 0,9640</td><td> 0,9611</td><td> 0,9640</td><td> 0,9593</td>

<td>GPC, M_in</td><td> 216,500</td><td> 229,900</td><td> 209,000</td><td> 200,800</td><td> 239,200</td><td>NB</td>

<td>GPC, Mw / Mn</td><td> 15,3</td><td> 17,4</td><td> 15,5</td><td> 12,6</td><td> 19,1</td><td>NB</td>

<td>RCD</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td>

<td>Border yield strength, MPa</td><td> 26,7</td><td> 23,5</td><td> 26,9</td><td> 23,7</td><td> 25,0</td><td> 23,1</td>

NB means "not tested"

PL 203 864 B1

As shown in Tables 4-6, for the product of Example 3 of the invention which was obtained by melt-blending three substantially equivalent batches from the polymerization trials to obtain a sufficient amount of product (i.e., Examples 3a, 3b and 3c), each trial was carried out in a manner similar to that described in Example 1 of the invention above. The product of Example 3 of the invention was stabilized and mixed with carbon black in a similar manner to Example 1 of the invention, except that, as shown in Table 7, its melt index I5 was 0.42 g / 10 minutes and the density was 0. 9640 g / cm³. As shown in Tables 4-6, for the product of Example 4 of the invention which was obtained by dry blending two substantially equivalent batches from the polymerization trials to obtain a sufficient amount of product (i.e., Examples 4a and 4b), each trial was was carried out in a manner similar to that described in Example 1 of the invention above. The product of Example 4 of the invention was stabilized and mixed with carbon black in a similar manner to Example 1 of the invention, except that, as shown in Table 7, its melt index I5 was 0.41 g / 10 minutes and the density was 0. 9611 g / cm³.

Comparative Run 1 was HOSTALEN CRP 100, commercially available from BASELL as a PE100 pressure pipe resin. Comparative run 1 had a melt index I5 of 0.21 g / 10 minutes and a density of 0.9640 g / cm³ and is labeled in the pressure pipe industry as the PE100 resin with the highest hydrostatic resistance. HOSTALEN CRP 100 is produced exclusively using a Ziegler-Natta catalyst in a two-reactor system.

Comparative Test 2 was a HDPE PE100 resin for pressure pipes. Comparative run 2 had a melt index of I5 of 0.40 g / 10 minutes and a density of 0.9593 g / m³. Like CRP 100, this resin is made using a common Ziegler-Natta catalyst system. Differential scanning calorimetry analysis was performed using a Seiko DSC apparatus to determine the crystallinity and peak melting point.

Creep cracking tests were carried out in a Frank type 68317 creep apparatus with 15 sample stands. Figure 2 shows the device, except that only one sample station is shown from the front and side, and not all 15 stations. The stand is equipped with an optical extensiometer for measuring deformation and a dryer enabling measurements at elevated temperature. Fittings for creep tests (e.g. in the shape of a dog bone), were punched out of compression pressed rectangular plates with a nominal thickness of about 2 mm. The dimensions of the dog bone measurement bars were in accordance with ASTM D412, specimen type C. The plates were compression pressed under conditions in accordance with ASTM D1928. The cross-sectional area of ​​each fitting was individually measured to ensure that the necessary load applied to achieve the required stress level was accurately calculated. During the tests, the time to failure was recorded and the course of creep was monitored using an optical extensiometer installed in the creep measurement set. In order to monitor the course of creep, two marking lines were drawn in the central part of the samples along their entire width, at a distance of 35 mm from each other. When tested at elevated temperature, the dryer was heated to the desired temperature before placing the samples therein. After the dryer equilibrated at the desired elevated temperature, it was turned off, the dryer was opened and samples were placed therein, the dryer door was closed and the dryer was turned back on. This lasted for 10-15 minutes, with the dryer reaching thermal equilibrium shortly after placing the samples in it. One hour after the creep dryer door was closed, zero strain was measured and the samples were loaded. At appropriate time intervals, the elongation of the sample was determined with an optical extensiometer to determine the creep curve. The time to failure was measured with a timer that responded to both the mechanical switch and the magnetic switch as shown in Fig. 2. The timer was only active when both switches were in the "on" position. Each sample stand in the creep tester is equipped with its own timer.

As a result of the load, the spring at the top of the creep tester compresses which causes the mechanical switch to activate the clock. A strip of metal on the lower sample clamp keeps the magnetic switch active. As the strip of metal moves downward as the sample lengthens during the test, the magnetic switch stops the clock at an elongation which depends on the position of the strip on the clamp. The adjustable strap is mounted in such a way that the clock turns off with an elongation of 200%. The clock measures the time to destruction with an accuracy of 0.05 hours.

PL 203 864 B1

Table 8 - Actual and calculated times to failure in creep test at various temperatures and stresses

<td colspan="4"></td><td colspan="3">Example 1 according to the invention, times are calculated</td><td colspan="2"></td><td colspan="3">Example 2 times calculated according to the invention</td>

<td>Temp. ° C (K)</td><td>Tension MPa</td><td>Comparison test 1 Service life real</td><td>Example 1 according to the invention Lifetime of real</td><td>Equation 1</td><td>Equation 2</td><td>Equation 3</td><td>Attempt to compare 2 Service life real</td><td>Example 2 according to the invention Service life real</td><td>Equation 1</td><td>Equation 2</td><td>Equation 3</td>

<td> 22,85 (296)</td><td> 12,49</td><td> 2483</td><td> 3966</td><td> 3494</td><td> 3481</td><td> 3472</td><td>NB</td><td> 2590</td><td>NB</td><td>NB</td><td>NB</td>

<td> 22,85 (296)</td><td> 12,6</td><td> 2406</td><td> 3623</td><td> 3379</td><td> 3366</td><td> 3358</td><td> 1217</td><td> 2620</td><td> 1640</td><td> 1634</td><td> 1630</td>

<td> 22,85 (296)</td><td> 12,94</td><td> 1670</td><td>NB</td><td> 2294</td><td> 2285</td><td> 2280</td><td> 568</td><td> 1410</td><td> 731</td><td> 728</td><td> 726</td>

<td> 22,85 (296)</td><td> 13,4</td><td> 450</td><td> 1305</td><td> 571</td><td> 569</td><td> 567</td><td> 309</td><td> 890</td><td> 338</td><td> 382</td><td> 381</td>

<td> 59,85 (333)</td><td> 7,93</td><td> 552</td><td>NB</td><td> 1304</td><td> 1635</td><td> 1820</td><td> 1320</td><td> 10000</td><td> 3288</td><td> 4122</td><td> 4589</td>

<td> 59,85 (333)</td><td> 8,17</td><td> 700</td><td> 2000</td><td> 1678</td><td> 2103</td><td> 2342</td><td> 300</td><td>NB</td><td> 683</td><td> 856</td><td> 953</td>

<td> 59,85 (333)</td><td> 8,34</td><td> 350</td><td> 1100</td><td> 804</td><td> 1008</td><td> 1123</td><td> 120</td><td> 475</td><td> 258</td><td> 324</td><td> 361</td>

<td> 59,85 (333)</td><td> 8,69</td><td> 90</td><td> 320</td><td> 190</td><td> 239</td><td> 266</td><td>NB</td><td> 83</td><td>NB</td><td>NB</td><td>NB</td>

<td> 79,85 (353)</td><td> 6,3</td><td> 225</td><td> 4320</td><td> 663</td><td> 923</td><td> 1080</td><td> 552</td><td>NB</td><td> 1719</td><td> 2391</td><td> 2798</td>

<td> 79,85 (353)</td><td> 6,37</td><td> 215</td><td> 6528</td><td> 632</td><td> 880</td><td> 1029</td><td> 313</td><td> 2850</td><td> 942</td><td> 1310</td><td> 1533</td>

<td> 79,85 (353)</td><td> 6,54</td><td> 22</td><td> 969</td><td> 56</td><td> 78</td><td> 92</td><td> 140</td><td> 200</td><td> 401</td><td> 558</td><td> 653</td>

<td> 79,85 (353)</td><td> 6,68</td><td> 30</td><td> 135</td><td> 32</td><td> 109</td><td> 127</td><td> 10</td><td> 119</td><td> 24</td><td> 34</td><td> 40</td>

NB means - Not Tested or Calculated.

Table 9 - Minimum wrap stress requirements for PE100

<td>Temperature, ° C</td><td>Wrap stress, MPa</td><td>Minimum time to destruction, hours</td>

<td> 20</td><td> 12,4</td><td> &gt; 100</td>

<td> 80</td><td> 5,5</td><td> &gt; 165</td>

<td> 80</td><td> 5</td><td> &gt; 1000</td>

Table 10 - Results of the wrap-around stress measurements

<td>Example according to the invention</td><td>Temp. ° C</td><td>Diameter outside mm</td><td>Minimum wall thickness mm</td><td>Pressure kPa</td><td>Tension belting MPa</td><td>Time to the destruction of the hour</td>

<td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td>

<td> 2</td><td> 20</td><td> 32,00</td><td> 2,85</td><td> 24,22·10²</td><td> 12,39</td><td> &gt; 3397</td>

<td> 2</td><td> 60</td><td> 31,90</td><td> 2,81</td><td> 15,50·10²</td><td> 8,02</td><td> &gt; 8088</td>

<td> 2</td><td> 60</td><td> 31,90</td><td> 2,66</td><td> 14,51 ·10²</td><td> 7,98</td><td> &gt; 8088</td>

<td> 2</td><td> 60</td><td> 32,00</td><td> 2,78</td><td> 14,51 ·10²</td><td> 7,63</td><td> &gt; 8088</td>

<td> 2</td><td> 60</td><td> 31,95</td><td> 2,86</td><td> 14,91 ·10²</td><td> 7,58</td><td> &gt; 8088</td>

<td> 2</td><td> 80</td><td> 31,80</td><td> 2,79</td><td> 10,59·10²</td><td> 5,51</td><td> &gt; 8088</td>

<td> 2</td><td> 80</td><td> 31,85</td><td> 2,86</td><td> 10,79·10²</td><td> 5,47</td><td> &gt; 8088</td>

The table continues. 10

<td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td>

<td> 2</td><td> 80</td><td> 32,00</td><td> 2,80</td><td> 9,61-10²</td><td> 5,01</td><td> &gt; 8088</td>

<td> 2</td><td> 80</td><td> 31,82</td><td> 2,79</td><td> 9,61-10²</td><td> 5,00</td><td> &gt; 8088</td>

<td> 2</td><td> 80</td><td> 31,97</td><td> 2,82</td><td> 9,51-10²</td><td> 4,89</td><td> &gt; 8088</td>

<td> 3</td><td> 20</td><td> 31,90</td><td> 2,78</td><td> 23,73-10²</td><td> 12,43</td><td> &gt; 8040</td>

<td> 3</td><td> 60</td><td> 31,90</td><td> 2,88</td><td> 15,89-10²</td><td> 8,00</td><td> 5819</td>

<td> 3</td><td> 60</td><td> 31,90</td><td> 2,85</td><td> 15,69-10²</td><td> 8,00</td><td> 7412</td>

<td> 3</td><td> 60</td><td> 31,90</td><td> 2,81</td><td> 14,71-10²</td><td> 7,61</td><td> &gt; 8040</td>

<td> 3</td><td> 60</td><td> 31,90</td><td> 2,82</td><td> 14,71-10²</td><td> 7,61</td><td> &gt; 8040</td>

<td> 3</td><td> 80</td><td> 31,90</td><td> 2,89</td><td> 10,98-10²</td><td> 5,51</td><td> 2098</td>

<td> 3</td><td> 80</td><td> 31,90</td><td> 2,90</td><td> 10,98-10²</td><td> 5,49</td><td> 1525</td>

<td> 3</td><td> 80</td><td> 31,90</td><td> 2,85</td><td> 9,81-10²</td><td> 5,00</td><td> 1936</td>

<td> 3</td><td> 80</td><td> 31,90</td><td> 2,86</td><td> 9,81-10²</td><td> 4,98</td><td> 4115</td>

<td> 3</td><td> 80</td><td> 31,90</td><td> 2,91</td><td> 9,81-10²</td><td> 4,89</td><td> 1967</td>

<td> 4</td><td> 20</td><td> 32,00</td><td> 2,80</td><td> 23,73-10²</td><td> 12,38</td><td> 3372</td>

<td> 4</td><td> 60</td><td> 32,00</td><td> 2,82</td><td> 15,50-10²</td><td> 8,02</td><td> 4251</td>

<td> 4</td><td> 60</td><td> 32,00</td><td> 2,82</td><td> 15,50-10²</td><td> 8,02</td><td> 3271</td>

<td> 4</td><td> 60</td><td> 32,00</td><td> 2,80</td><td> 14,51-10²</td><td> 7,57</td><td> &gt; 8064</td>

<td> 4</td><td> 60</td><td> 32,00</td><td> 2,78</td><td> 14,51-10²</td><td> 7,63</td><td> &gt; 8064</td>

<td> 4</td><td> 80</td><td> 32,00</td><td> 2,81</td><td> 10,79-10²</td><td> 5,60</td><td> &gt; 8064</td>

<td> 4</td><td> 80</td><td> 32,00</td><td> 2,81</td><td> 10,59-10²</td><td> 5,50</td><td> &gt; 8064</td>

<td> 4</td><td> 80</td><td> 32,00</td><td> 2,81</td><td> 10,59-10²</td><td> 5,50</td><td> &gt; 8064</td>

<td> 4</td><td> 80</td><td> 32,00</td><td> 2,84</td><td> 10,10-10²</td><td> 5,19</td><td> &gt; 8064</td>

<td> 4</td><td> 80</td><td> 32,00</td><td> 2,69</td><td> 9,22-10²</td><td> 5,02</td><td> &gt; 8064</td>

<td> 4</td><td> 80</td><td> 32,00</td><td> 2,81</td><td> 9,61-10²</td><td> 4,99</td><td> &gt; 8064</td>

<td> 4</td><td> 80</td><td> 32,00</td><td> 2,83</td><td> 9,51-10²</td><td> 4,90</td><td> &gt; 8064</td>

Table 8 compares the service life of the polymers of the various examples under different stresses at 23, 60 and 80 ° C. Comparing the inventive example 1 with comparative test 1 and the inventive example 2 with comparative test 2, it is clear that for all stresses tested at all temperatures, the pot life of the inventive examples was significantly longer than that of the comparative tests.

Algebraic equations were derived to describe the differences in durability. For the lifetime t1 in the comparative test, the lifetime t2 for the example according to the invention was longer in a given T (in Kelvin), the relationships being as follows:

Preferably log t₂ &gt; 1.0607 x logt₁ + 2,324 - 707 / T equation (1)

More preferably log t2&gt; 1.0607 x logt1 + 3.221 - 971 / T equation (2)

Most preferably log t2&gt; 1.0607 x logt1 + 3.649-1098 / T equation (3).

A comparison of the lives measured for the examples of the invention with the lives calculated from Equations 1-3 above is also shown in Table 8.

In order to compare the surrounding stresses, the pressure requirements for PE100 according to European Standard ISO / DIS 4437 are given in table 9. In addition to the above data on the service life up to

From creep cracking, Table 10 shows that the compositions of the inventive examples also exhibit a more favorable hover stress when the hydrostatic strength of the 32 mm SDR 11 pipe samples was measured according to ISO 1167. Accordingly, Tables 8-10 it is clear that the compositions of the examples according to the invention far exceed the requirements of the standard for PE100 pressure pipes.

In other evaluation trials, two additional exemplary resins of the invention were prepared. These resins, of Examples 5 and 6 of the invention, were prepared in the same reactor system and in a manner substantially equivalent to the method described in Example 1 of the invention, including melt mixing to increase sample size. However, instead of injecting fresh catalyst into each reactor as in the case of Example 1 of the invention, in these examples only fresh catalyst was injected into the first reactor and no catalyst was injected into the second reactor. In addition, the process conditions were adjusted such that the catalyst remained active in both reactors. In addition, Examples 5 and 6 of the invention were identical except for the addition of additives. Table 11 shows the product and performance data as well as the mixing data with the additives.

The critical GC strain energy release rate was measured in a Charpy system according to the procedure described by E. Plati and JG Williams in Polymer Engineering and Science, June 1975, Vol. 15, No. 6, pp. 470-477. For each temperature, at least 6 samples with dimensions of 125 mm × 10 mm × 10 mm were used. The bars are machined from thick compression molded sheets. As the procedure for forming these sheets, modifications to the procedure set forth in "A compression molding technique for thick sheets of thermoplastics" by MJ Cawood and GAH Smith in Polymer Testing, 1 (1980), 3-7 were used.

The samples were compression molded in a 10 mm thick mold which was laterally insulated with Teflon ™. The samples were heated to 160 ° C and held at a pressure of 6.7MPa for 3 minutes followed by 3 one-minute press-and-release cycles. Excessive ironing seam was removed. The material was then heated to 180 ° C and held for approximately 5 minutes at a pressure of 6.7MPa, also followed by 3 one-minute press-and-release cycles. The melt was finally solidified at a pressure of 1.7 MPa and cooled slowly overnight by turning off the heating.

Pennsylvania Notch Test (PENT), the slow crack growth test was performed according to the procedure described by X. Lu and N. Brown, Polymer Testing, 11 (1992), pp. 309-319. In the PENT method, a fitting with a cut on one edge is subjected to a constant load at a carefully controlled temperature. The time to failure can be measured with a clock and the rate of failure can be measured under a microscope or a sensing gauge. The cut depth is typically about 35% of the thickness of the formed body. The notch width may range from about 15 to about 25 mm and the side groove may range from about 0.5 to about 1.0 mm depending on the width of the formed body.

An incision is made in the shaped body by pressing the blade of a new razor blade into the shaped piece at a speed of about 300 µm / minute. At a speed of about 300 µm / minute, damage to the cut tip is avoided and still a reasonably short notching time is achieved. At notching speeds above about 525 µm / minute, the time to failure increases significantly. The cutting speeds of the side grooves are not particularly critical. The apparatus used should ensure that the incision and side grooves are coplanar.

During the test, ensure that the sample holders are correctly positioned. For this purpose, the grips should be aligned and centered with respect to the longitudinal axis of the specimen. During clamping, the incision should not be activated by bending or twisting the specimen. A tuning jig may be used to facilitate proper fixation of the specimen by aligning the fixtures and avoiding bending or twisting the specimen. In addition, the planes of the handles should be serrated to prevent slipping, and the ends of the handles should be at least 10mm from the cut.

The measuring device may be a direct loading device or a lever loading device. A 5: 1 leverage ratio has been found to be very convenient. The grips can be connected to the loading device by means of universal action tabs such that the applied load is pure tensile stress.

The applied load is calculated for the cross-section of the sample without taking into account the incision. The value of the applied load depends on the measurement temperature. A value that causes rapid destruction as soon as possible is recommended. At higher stresses, there is ductile failure and lower stresses during the test. In the case of polyethylenes, for

After the maximum load corresponding to brittle fracture, the applied load should be 5.6, 4.6, 4.2 and 2.4 MPa, at 23, 42, 50 and 80 ° C, respectively. In general, the load at which brittle fracture occurs as a result of slow crack growth should be less than half the yield strength at a given measurement temperature.

The temperature should be regulated within ± 0.5 ° C. It is not recommended to test polyethylene at temperatures above 80 ° C, as significant morphological changes may occur during the test. In general, depending on the test temperature, a 1 ° C change in pass temperature will result in a 10-15% change in time to failure.

A simple timer can be used to record the time to destruction. The timer should be configured to turn off when the sample breaks. The rate of slow crack growth can be monitored microscopically at 2 - 100 x magnification by measuring the critical crack opening shift over time. A dial gauge that measures the overall elongation of a specimen can also detect the onset of crack initiation.

The PENT measurements, the results of which are shown, were carried out at 2.4 MPa and 80 ° C. Samples with dimensions of 50 mm x 25 mm x 10 mm were used, made by cutting from the same sheet as the bars for Gc measurements.

Viscosities were measured with a Rheometrics Mechanical Spectrometer (RMS) at 190 ° C in oscillating mode.

Melt strength measurements were made at 190 ° C using a Goettfert Rheotens apparatus and an Instron capillary rheometer. A capillary rheometer tuned and positioned above the Rheotens unit, fed the molten polymer fiber to the Rheotens unit at a constant piston speed of 25.4 mm / min. The Instron rheometer was equipped with a common capillary nozzle 2.1 mm in diameter and 42 mm long (20: 1 L / D) and fed the fiber to the gear wheels receiving the Rheotens units rotating at a linear speed of 10 mm / s. The distance between the exit of the Instron capillary die and the nip point on the Rheotens take-up wheels was 100 mm. An experiment to measure the alloy strength was started by accelerating the receiving wheels of the Rheotens units by 2.4 mm / s², the range of possible accelerations of the Rheotens unit is 0.12-120 mm / s². As the speed of the Rheotens take-up wheels increases with time, the downward pull force was recorded in centiNewtons (cN) using a linear variable displacement transducer (LVDT) on the Rheotens unit. The computerized data acquisition system of the Rheotens unit records the downward pulling force as a function of the speed of the pick-up wheels, in cN / s. The actual value of the melt strength is taken for a plateau of tensile force downwards in cN. The speed at fiber break in cm / s is also recorded as the melt break speed.

Table 11 - Product and performance properties

<td>Example according to the invention</td><td></td><td> 2</td><td> 5</td><td> 6</td>

<td>Melt flow index</td><td></td><td></td><td></td><td></td>

<td>I5</td><td>g / 10 minutes</td><td> 0,21</td><td> 0,25</td><td> 0,25</td>

<td>I21.6</td><td>g / 10 minutes</td><td> 4,71</td><td> 5,04</td><td> 6,31</td>

<td>I21.6 / I5</td><td></td><td> 22,43</td><td> 20,16</td><td> 25,24</td>

<td>Density</td><td>g / cm³</td><td> 0,9511</td><td> 0,9508</td><td> 0,9508</td>

<td>Butene (FTIR)</td><td>mole%</td><td> 0,53</td><td> 0,45</td><td>NB</td>

<td>GPC</td><td></td><td></td><td></td><td></td>

<td>Mw</td><td></td><td> 229900</td><td> 223100</td><td> 201400</td>

<td>Me</td><td></td><td> 13213</td><td> 15200</td><td> 15700</td>

<td>Mw / Mn</td><td></td><td> 17,4</td><td> 14,68</td><td> 12,83</td>

<td>Mz</td><td></td><td></td><td> 832600</td><td> 727200</td>

<td>RCD (fractionation)</td><td></td><td>Yes</td><td>Yes</td><td>Yes</td>

<td>Calcium stearate</td><td>ppm</td><td></td><td> 680</td><td></td>

<td>Irganox ™ 1010</td><td>ppm</td><td> 2080</td><td> 845</td><td> 329</td>

<td>Irgafos ™ 168 total</td><td>ppm</td><td> 2691</td><td></td><td> 1900</td>

<td>Irgafos ™ 168 remaining</td><td>ppm</td><td> 2784</td><td> 2000</td><td> 1723</td>

Table 11 continues

<td>Example according to the invention</td><td></td><td> 2</td><td> 5</td><td> 6</td>

<td>DSC</td><td></td><td></td><td></td><td></td>

<td>This</td><td>° C</td><td> 122,2</td><td> 122,1</td><td> 121,2</td>

<td>Tm</td><td>° C</td><td> 133,2</td><td> 134,4</td><td> 133,1</td>

<td>Crystallinity</td><td> %</td><td> 72,77</td><td> 68,11</td><td> 69,0</td>

<td>OIT ° C</td><td>min.</td><td> 66</td><td> 46</td><td> 50</td>

<td>PENT</td><td>min.</td><td> &gt; 464484</td><td> &gt;179796</td><td> &gt;150000</td>

<td>Gc of brittle-ductile transformation ° C</td><td></td><td></td><td></td><td></td>

<td> 40</td><td>kJ / m²</td><td> 33</td><td> 36,7 ^d</td><td> 39,8 ^d</td>

<td> 23</td><td>kJ / m²</td><td></td><td></td><td></td>

<td> 0</td><td>kJ / m²</td><td></td><td></td><td></td>

<td> -5</td><td></td><td></td><td></td><td></td>

<td> -10</td><td>kJ / m²</td><td></td><td> 21,5 ^d</td><td> 23,2 ^d</td>

<td> -20</td><td>kJ / m²</td><td> 18,4</td><td> 17,7 ^d</td><td> 21,0 ^d</td>

<td> -30</td><td>kJ / m²</td><td></td><td> 17,1 ^d</td><td> 17,4 ^d</td>

<td> -40</td><td>kJ / m²</td><td></td><td> 14,5 ^d</td><td> 17,1 ^d</td>

<td> -50</td><td>kJ / m²</td><td></td><td> 13,6 ^d</td><td> 12,5 ^b</td>

<td> -60</td><td>kJ / m²</td><td></td><td> 12,8 ^b</td><td> 12,0 ^b</td>

<td>Izod impact strength</td><td>kJ / m²</td><td> 545</td><td> 44,6</td><td> 44,7</td>

<td>Properties in stretching Yield point</td><td>MPa</td><td> 23,1</td><td> 23,7</td><td> 24,8</td>

<td>Strain at yield point</td><td> %</td><td> 11,7</td><td> 10,6</td><td> 11,0</td>

<td>Breaking stress</td><td>MPa</td><td> 36,6</td><td> 42,4</td><td> 42,2</td>

<td>Ultimate tensile stress</td><td>MPa</td><td> 36,6</td><td> 42,4</td><td> 42,2</td>

<td>Elongation</td><td> %</td><td> 673</td><td> 683</td><td> 697</td>

<td>Incisal module</td><td>MPa</td><td> 556</td><td> 622</td><td> 614</td>

<td>Young's modulus</td><td>MPa</td><td> 954</td><td> 1044</td><td> 957</td>

<td>Three-point modulus of elasticity</td><td>MPa</td><td> 831</td><td> 918</td><td> 983</td>

<td>Rheology Viscosity, about 1 / s</td><td></td><td> 88371</td><td> 86924</td><td> 81283</td>

<td>Viscosity, about 100 / s</td><td></td><td> 3100</td><td> 2879</td><td> 2680</td>

<td>Exponent k</td><td></td><td> 37311</td><td> 35654</td><td> 34597</td>

<td>Exponent N</td><td></td><td> 0,50565</td><td> 0,4972</td><td> 0,4747</td>

<td>Stop stretching Snail</td><td>revolutions / minute</td><td></td><td> 27,9</td><td> 27,0</td>

<td>Pressure</td><td>kPa</td><td></td><td> 107·10²</td><td> 115·10²</td>

<td>Vo</td><td>cm / s</td><td></td><td> 3,1</td><td> 3,2</td>

<td>Vz</td><td>cm / s</td><td></td><td> 46,0</td><td> 53</td>

<td>Me</td><td></td><td></td><td> 13,84</td><td> 15,56</td>

<td>Force</td><td>cN</td><td></td><td> 44,0</td><td> 38,0</td>

<td>Tz</td><td>cN / s</td><td></td><td> 8225</td><td> 8675</td>

<td>Swelling</td><td> %</td><td></td><td> 127</td><td> 122</td>

b: indicates that brittle cracking is observed; d: means that ductile cracking is observed.

PL 203 864 B1

Based on the data in Table 11, plots were made to illustrate the low temperature ductile fracture point, slow crack growth and rapid crack propagation (based on Gc and PENT data). Fig. 2 shows that the composition of Example 5 according to the invention has a distinctive balance between slow crack growth and fast crack propagation with respect to PE80 and PE100 standards. From fig. 3 it appears that the compositions of examples 2, 5 and 6 according to the invention show an excellent low Tdb. In addition, true creep cracking was performed for the various compositions of the inventive examples with direct comparison with comparative tests 1 and 2. Fig. 4 shows that while at 80 ° C and a stress of 5.8 MPa the service life of the comparative tests was about seven (7) days, the extrapolated service life of the compositions of Examples 2, 5 and 6 according to the invention was 1,400 days (i.e. 2,000,000 minutes or 33,000 hours) .

In other evaluation trials, the differences between injecting catalyst twice and injecting catalyst once were further investigated. In this case, the polymer of example 7 of the invention was made with a double injection of the catalyst, and the polymer of example 8 of the invention was made with a single injection of the catalyst. The same supported CGC borate catalyst system was used in each synthesis as used in Example 1 of the invention.

In Example 7 of the invention, the polymerization was carried out continuously in a first continuously stirred tank reactor (CSTR) operating with a liquid volume of 130 liters in hexane form as diluent. The catalyst was injected as a slurry in hexane as the carrier liquid in the reactor. The temperature of the liquid in the reactor was kept constant by circulating cold water through the reactor jacket. Hexane, ethylene and hydrogen were fed into the first reactor. The melt flow rate of the powder produced in the reactor was controlled by the rate of the hydrogen stream. The liquid volume was kept at 130 liters by transferring the slurry from the first reactor to the stripper.

The stripper contained 110 liters of liquid and operated at an overpressure of 40 kPa and a temperature of 40 ° C. The temperature was regulated by circulating cold water through the jacket of the stripper and the pressure was controlled by degassing the stripped gas phase. The hexane feed rate was 60 liters / hour. In the stripper, substantially no polymerization took place and undissolved hydrogen was removed from the liquid. The liquid volume in the stripper was kept at 110 liters by transferring the contents of the stripper to a second CSTR in series with the first CSTR.

The temperature in the second reactor was maintained at 70 ° C by circulating cold water through the reactor jacket. Ethylene was fed to the second reactor to regulate the split and butene as comonomer was fed to the second reactor to regulate the product density. The same catalyst system that was fed to the first reactor was also fed separately to the second reactor. The melt flow rate of the product obtained in the second reactor was controlled by adjusting the hydrogen concentration in the reactor by continuously degassing the gas phase from the reactor. The liquid volume was kept at 180 liters by batching the slurry from the second reactor to a fluid bed dryer where the powder product was separated from the liquid and unreacted monomers. The powder product was further dried on a rotary dryer to obtain a dry powder product. The test conditions are given in Table 12.

Powder samples from a two reactor system were dry mixed with 2400 ppm Irganox B215 and 750 ppm calcium stearate and then melt mixed in a Leistritz homogenizing extruder operating at a temperature profile of 190 - 220 ° C with a throughput of 30 kg / hour and speed of 40 revolutions / minute (minimum specific energy). Nitrogen purge was used to minimize the presence of oxygen; the product was melt mixed three times before being evaluated. The product of Inventive Example 8 was prepared as described in Inventive Example 7, except that no catalyst was charged to the second reactor.

In this test, melt index and melt index ratios were determined according to ASTM D-1238; the comonomer content was measured by Fourier Transform Infrared (FTIR) spectroscopy; molecular weight distributions were measured by high temperature GPC; the tendency to slow crack growth was assessed by PENT viability (Pennsylvania Notch Test); the critical strain energy release rate, or Gc, was determined as described above; and the viscosity was measured with a Bohlin Constant apparatus

PL 203 864 B1

Stress Rheometer in oscillation mode, at 190 ° C, with angular velocities varied from 0.1-100 rad / s. The viscosity at 100 rad / s is typical of resin processing conditions in industrial equipment: the lower the viscosity, the easier the processing will be. The viscosity at 0.1 rad / s is proportional to the melt strength of the material. The ratio of the two viscosities also provides information regarding the shear sensitivity of the material. The different properties of the products of Examples 7 and 8 according to the invention compared to that of Comparative Test 2 are given in Table 13.

Table 13 shows that the toughness, as measured by Gc at various temperatures, of the products of Examples 7 and 8 according to the invention was excellent as both products had a very low brittle-to-ductile transition temperature, close to -50 ° C. The slow crack growth resistance as determined by the PENT method of the products of Examples 7 and 8 according to the invention was also excellent as both products had a PENT life of over 140,000 minutes. Accordingly, these resins have a unique combination of very low brittle and ductile transition temperatures and good slow crack growth resistance.

To evaluate the performance of the pipes, 32 mm SDR pipes 11 were made from the products of Examples 7 and 8 according to the invention and from Comparative Test 2 using a Weber NE 45 pipe extruder. The extruder comprised a single screw with a diameter of 45 mm and a length of 30 D, followed by This was a typical polyethylene production line, including a Weber type PO calibrating ring, two 6.6 m long cooling baths with vacuum calibration in the first bath, a crawler winch and a cutting device. The manufactured pipes were subjected to hydrostatic tests in accordance with ISO 1167. The results of the measurements of the wrap around stress for the pipes are given in Tables 14-16.

Table 12 - Test conditions

<td colspan="3">Example according to the invention</td><td> 7</td><td> 8</td>

<td>R1</td><td>Temperature</td><td>° C</td><td> 70</td><td> 70</td>

<td></td><td>Hypertension</td><td>kPa</td><td> 5,9·10²</td><td> 1,9·10²</td>

<td></td><td>Hexane flow rate</td><td>liters / hour</td><td> 70</td><td> 70</td>

<td></td><td>Ethylene flow rate</td><td>kg / hour</td><td> 8,9</td><td> 8,1</td>

<td></td><td>Hydrogen flow rate</td><td>N-liters / hour</td><td> 34</td><td> 26</td>

<td></td><td>Catalyst flow rate</td><td>g / hour</td><td> 4,7</td><td> 13,7</td>

<td></td><td>Performance</td><td>kg / hour</td><td> 6,7</td><td> 7,7</td>

<td>R2</td><td>Temperature</td><td>° C</td><td> 70</td><td> 70</td>

<td></td><td>Hypertension</td><td>kPa</td><td> 4,7·10²</td><td> 4,0·10²</td>

<td></td><td>Hexane flow rate</td><td>liters / hour</td><td> 40</td><td> -</td>

<td></td><td>Ethylene flow rate</td><td>kg / hour</td><td> 10,6</td><td> 9,3</td>

<td></td><td>Butene flow rate</td><td>liters / hour</td><td> 0,64</td><td> 0,73</td>

<td></td><td>Catalyst flow rate</td><td>g / hour</td><td> 4,7</td><td> -</td>

<td></td><td>Degassing flow rate</td><td>kg / hour</td><td> 2,0</td><td> 0,5</td>

<td></td><td>Performance</td><td>kg / hour</td><td> 7,4</td><td> 8,0</td>

Table 13 - Product properties

<td colspan="2"></td><td>Example 7 according to the invention</td><td>Example 8 according to the invention</td><td>Attempt comparative 2</td>

<td>Melt flow index</td><td></td><td></td><td></td><td></td>

<td>I5</td><td>g / 10 min</td><td> 0,21</td><td> 0,17</td><td> 0,40</td>

<td>I10</td><td>g / 10 min</td><td> 0,79</td><td> 0,66</td><td></td>

<td>I21.6</td><td>g / 10 min</td><td> 5,72</td><td> 4,87</td><td> 9,39</td>

<td>The ratio is 121.6 / I5</td><td> -</td><td> 27,24</td><td> 28,65</td><td> 22,70</td>

Table 13 continues

<td colspan="2"></td><td>Example 7 according to the invention</td><td>Example 8 according to the invention</td><td>Attempt comparative 2</td>

<td>Density</td><td>g / cm³</td><td> 0, 951</td><td> 0,9493</td><td> 0,9593</td>

<td>Comonomer</td><td>mole%</td><td> 0,45</td><td> 0,55</td><td></td>

<td>GPC results</td><td>Mw</td><td> 226400</td><td> 246800</td><td></td>

<td></td><td>Mw / Mn</td><td> 15,61</td><td> 15,14</td><td></td>

<td>RCD</td><td></td><td>Yes</td><td>Yes</td><td>no</td>

<td>Rheology</td><td></td><td></td><td></td><td></td>

<td>Viscosity at about 0.1 / s</td><td>Crimson</td><td> 95622</td><td> 109292</td><td> 60703</td>

<td>Viscosity at about 100 / s</td><td>Crimson</td><td> 2758</td><td> 2860</td><td> 2338</td>

<td>Properties in stretching</td><td></td><td></td><td></td><td></td>

<td>Yield point</td><td>MPa</td><td> 24,25</td><td> 24,09</td><td> 23,08</td>

<td>Young's modulus in tension</td><td>MPa</td><td> 1013</td><td> 1002</td><td> 986</td>

<td>Young's modulus in bending</td><td>MPa</td><td> 1014</td><td> 921</td><td></td>

<td>Gc transition from brittle to plastic</td><td></td><td></td><td></td><td></td>

<td>40 ° C</td><td>kJ / m²</td><td> 45,5 ^d</td><td> 48,5 ^d</td><td></td>

<td>23 ° C</td><td>kJ / m²</td><td> 36,6 ^d</td><td> 43,6 ^d</td><td> 11</td>

<td>0 ° C</td><td>kJ / m²</td><td> 26,9 ^d</td><td> 29,2 ^d</td><td></td>

<td>-10 ° C</td><td>kJ / m²</td><td> 23,3 ^d</td><td> 25,8 ^d</td><td></td>

<td>-20 ° C</td><td>kJ / m²</td><td> 22,1 ^d</td><td> 22,7 ^d</td><td></td>

<td>-30 ° C</td><td>kJ / m²</td><td> 19 ^d</td><td> 20,5 ^d</td><td></td>

<td>-50 ° C</td><td>kJ / m²</td><td> 19,1 ^d</td><td> 20,3 ^d</td><td></td>

<td>-60 ° C</td><td>kJ / m²</td><td> 14 ^b</td><td> 14,8 ^b</td><td></td>

<td>-70 ° C</td><td>kJ / m²</td><td> 13,2 ^b</td><td> 13,7 ^b</td><td></td>

<td>Pent [SCG]</td><td>minutes</td><td> &gt;142338</td><td> &gt; 200000</td><td> &gt;10000</td>

b: indicates that brittle cracking is observed

TABLE 14 - Results of the hover tension measurements for example 7 according to the invention

<td>Temperature, ° C</td><td>Tension, MPa</td><td>Time to destroy, hours</td><td>The nature of the destruction</td>

<td> 20</td><td> 12,9</td><td> 845,56</td><td>Ductile</td>

<td> 20</td><td> 12,95</td><td> 762,27</td><td>Ductile</td>

<td> 20</td><td> 13</td><td> 214,93</td><td>Ductile</td>

<td> 20</td><td> 13</td><td> 86,6</td><td>Ductile</td>

<td> 20</td><td> 13,05</td><td> 672,33</td><td>Ductile</td>

<td> 20</td><td> 13,1</td><td> 121,33</td><td>Ductile</td>

<td> 20</td><td> 13,2</td><td> 81,71</td><td>Ductile</td>

<td> 80</td><td> 6</td><td> 1484,85</td><td>Ductile</td>

<td> 80</td><td> 6,3</td><td> 1496,62</td><td>Ductile</td>

PL 203 864 B1

TABLE 15 - Results of the hover tension measurements for example 8 according to the invention

<td>Temperature, ° C</td><td>Tension, MPa</td><td>Time to destroy, hours</td><td>The nature of the destruction</td>

<td> 20</td><td> 12,7</td><td> 85,17</td><td>Ductile</td>

<td> 20</td><td> 12,7</td><td> 164,02</td><td>Ductile</td>

<td> 20</td><td> 12,75</td><td> 235,78</td><td>Ductile</td>

<td> 20</td><td> 12,8</td><td> 88,89</td><td>Ductile</td>

<td> 20</td><td> 12,8</td><td> 157,98</td><td>Ductile</td>

<td> 20</td><td> 12,85</td><td> 67,41</td><td>Ductile</td>

<td> 20</td><td> 12,9</td><td> 56,37</td><td>Ductile</td>

<td> 20</td><td> 12,95</td><td> 64,07</td><td>Ductile</td>

<td> 20</td><td> 13</td><td> 33,21</td><td>Ductile</td>

<td> 20</td><td> 13</td><td> 51</td><td>Ductile</td>

<td> 80</td><td> 5,5</td><td> 1505,43</td><td>Ductile</td>

<td> 80</td><td> 6,3</td><td> 24,09</td><td>Ductile</td>

Table 16 - Results of the hover stress measurements for comparative test 2

<td>Temperature, ° C</td><td>Tension, MPa</td><td>Time to destroy, hours</td><td>The nature of the destruction</td>

<td> 20</td><td> 13,06</td><td> 65</td><td>Ductile</td>

<td> 20</td><td> 13,02</td><td> 32</td><td>Ductile</td>

<td> 20</td><td> 12,97</td><td> 48</td><td>Ductile</td>

<td> 20</td><td> 12,97</td><td> 72</td><td>Ductile</td>

<td> 20</td><td> 12,55</td><td> 178</td><td>Ductile</td>

<td> 20</td><td> 12,5</td><td> 314</td><td>Ductile</td>

<td> 20</td><td> 12,45</td><td> 208</td><td>Ductile</td>

<td> 20</td><td> 12,09</td><td> 3120</td><td>Ductile</td>

<td> 20</td><td> 12,04</td><td> 3120</td><td>Ductile</td>

<td> 20</td><td> 11,98</td><td> 1285</td><td>Ductile</td>

<td> 20</td><td> 11,95</td><td> 3762</td><td>Ductile</td>

<td> 20</td><td> 11,9</td><td> 3120</td><td>Ductile</td>

<td> 20</td><td> 11,74</td><td> 9936</td><td>Ductile</td>

On the basis of these data, the following exponential equation for the product of example 7 according to the invention was derived by regression analysis, which for a 50-year service life predicts a breaking strength of more than 12.5 MPa at 20 ° C, which corresponds to the pressure class PE125:

Stress = 13.4 x time^-0,005 the stress is in MPa and the time in hours.

In Example 7 of the invention, no brittle failure occurred during the hover stress test at 80 ° C, 5.8 MPa for&gt; 4000 hours. In Example 8 according to the invention, the regression analysis predicts a stress of 11.6 MPa at 20 ° C for a 50-year service life according to the following exponential equation, which corresponds to the pressure class PE112:

Stress = 13.53 x time^-0,0118 the stress is in MPa and the time in hours.

PL 203 864 B1

In subsequent evaluation trials, the effect of the narrow MWD of the high molecular weight, low density component was investigated. Comparative Run 3 was performed as a single continuously stirred tank reactor slurry polymerization with a Ziegler-Natta catalyst system. The catalyst was undecanted alkoxide (NDA) and the product was prepared under the reaction conditions shown in Table 15. The obtained high-density product had an I2 melt index of 94 g / 10 minutes and a density of 0.9719 g / cm3.³and it was produced at a total pressure of 12 × 10² kPa, a hexane flow rate of 1500 g / hour, an ethylene feed rate of 816 g / hour, and a hydrogen feed rate of 140 N-liters / hour, and the average residence time in the reactor was 82 minutes.

Comparative test 4 was carried out with the same catalyst system as comparative test 3, under different conditions as shown in table 17. Comparative test 4 produced an ethylene / 1-butene copolymer with a melt index of I21.6 (conditions: 190 ° C). C, 21.6 kgf) 0.38 g / 10 minutes and a density of 0.9306 g / cm³. Comparative test 4 was carried out at a total pressure of 12 · 10² kPa, a hexane flow rate of 2800 g / hour, an ethylene feed rate of 856 g / hour, a hydrogen feed rate of 7.2 N-liter / hour, and a butene feed rate of 200 g / hour, and the average residence time in the reactor was 48 minutes.

Comparative Run 5 was a product sample taken directly downstream of the first reactor of the two-reactor suspension polymerization system. Comparative Run 5 was a high density product, a low molecular weight product with an I2 melt index of 118 g / 10 minutes and a density of 0.9720 g / cm.³.

The product of Comparative Run 6 was prepared using a constrained supported catalyst system, designated "CGC" herein, as described above in Example 1 of the invention. The product of Comparative Run 6 was prepared in a one-pot slurry polymerization system using a 26 liter CSTR (continuous stirred tank reactor) with adequate agitation to keep the particles in suspension. The reactor contained a jacket to remove the heat of reaction. A fixed stream of 5900 g / h of propane was fed to the reactor and a steady stream of nitrogen was introduced into the vapor space of the reactor. The reactor overpressure was controlled by degassing; 2500 g / h of ethylene and 4.96 N-liters / h of hydrogen were injected below the liquid level through a common tube. The CGC catalyst was injected with liquid propane diluent below the liquid level. The concentration of the CGC catalyst in the catalyst reservoir was 0.8 wt% in hexane and the solids were removed intermittently. During the synthesis, the reactor temperature was kept at 70 ° C and an overpressure of 55 · 10² kPa. Average residence time in the reactor was 60 minutes and the achieved polymer yield was 714 g / hour with a calculated catalyst yield of 170 813 g PE / g Ti. Details of the process conditions in Comparative Run 6 can be found in Table 14. Comparative Run 6 gave a high density product having an I2 melt index of 119 g / 10 minutes and a density of 0.9731 g / cm3.³.

The product of Comparative Run 7 was prepared using the same catalyst system and polymerization kit as Comparative Run 6 except that 163.4 g / h of hexene was fed into the reactor and the hydrogen flow was very low and diluted with nitrogen. The average residence time in Comparative Run 7 was 60 minutes and the achieved polymer yield was 441 g / hour with a calculated catalyst yield of 150,000 g PE / g Ti. In comparative test 7, an ethylene / 1-hexene copolymer with a melt index of I21.6 0.25 g / 10 minutes and a density of 0.9235 g / cm was obtained.³.

The properties of the products of Comparative Examples 3 - 7 can be found in Table 18. In the tests, the broad MWD component was abbreviated NDA as the product obtained using an undecanted alkoxide, a common Ziegler-Natta catalyst system. The narrow MWD component is abbreviated CGC as the product obtained using a constrained geometry catalyst system. Hence, the phrase "NDA / CGC" means that the low MW fraction has a wide MWD and the high MW fraction has a narrow MWD. NDA / NDA, CGC / NDA, and CGC / CGC are other designations used in these studies.

Comparative Run 8 was performed by dry blending the products of Comparative Runs 3 and 4 at a ratio of 48:52 (NDA / NDA). This material included the LMW component with a broad MWD and the HMW component with a broad MWD. 500 ppm of calcium stearate and 2250 ppm of Irganox B215 were added to this mixture. The mixture was then extruded using a small APV twin screw extruder at a melt temperature of 220 ° C and a melt pressure of 35-5010² kPa at 200 rpm. The productivity achieved was about 2.6 kg / hour, the energy consumption for extrusion was 0.24 kWh / kg. In the funnel

In the feed extruder, a nitrogen purge was also used to avoid or minimize the possibility of crosslinking following oxidation.

Comparative Run 9 was performed by dry blending the products of Comparative Runs 6 and 4 in a 48:52 ratio. The resulting CGC / NDA mixture contained a narrow MWD LMW component and a broad MWD HMW component. In the first pass the mixture was melt extruded at low temperature (140 ° C) and low throughput (0.4 kg / hour) using a small 60 mm Goettfert single screw extruder. In a second pass, the mixture was melt homogenized using an APV twin screw extruder under the same conditions.

Comparative 10 was made by dry blending the products of Comparative 5 and 7 in a 48:52 ratio. The resulting NDA / CGC blend contained a broad MWD LMW component and a narrow MWD HMW component. In the first pass the mixture was melt extruded at low temperature (140 ° C) and low throughput (0.4 kg / hour) using a small 60 mm Goettfert single screw extruder. In a second pass, the mixture was melt homogenized using an APV twin screw extruder under the same conditions.

Comparative Run 11 was made by dry blending the powder products of Comparative Runs 6 and 7 in a 48:52 ratio. The resulting CGC / CGC mixture contained a narrow MWD LMW component and a narrow MWD HMW component. In the first pass the mixture was melt extruded at low temperature (140 ° C) and low throughput (0.4 kg / hour) using a small 60 mm Goettfert single screw extruder. In a second pass, the mixture was melt homogenized using an APV twin screw extruder under the same conditions.

Table 17 - Reaction conditions and gas analysis for product manufacture in one reactor

<td>Example</td><td></td><td></td><td>attempt comparative 3</td><td>Attempt comparative 4</td><td>attempt comparative 6</td><td>attempt comparative 7</td>

<td>Catalyst</td><td></td><td></td><td>NDA</td><td>NDA</td><td>CGC</td><td>CGC</td>

<td>Conditions process</td><td>P (hypertension)</td><td>[kPa]</td><td> 12·10²</td><td> 12·10²</td><td> 55·10²</td><td> 55·10²</td>

<td></td><td>T.</td><td>° C</td><td> 88</td><td> 70</td><td> 70</td><td> 70</td>

<td></td><td>Flow C.₆</td><td>[g / hour]</td><td> 1501</td><td> 2800</td><td></td><td></td>

<td></td><td>Propane flow</td><td>[g / hour]</td><td></td><td></td><td> 5902</td><td> 5902</td>

<td></td><td>Tau (residence time)</td><td>[minutes]</td><td> 82</td><td> 48</td><td> 60</td><td> 60</td>

<td>Analysis gases</td><td>N2</td><td>[% vol.]</td><td> 0,87</td><td> 0,8533</td><td> 77,11</td><td> 78,14</td>

<td></td><td>H2</td><td>[% vol.]</td><td> 69,47</td><td> 4,746</td><td> 0,04</td><td> 0,002</td>

<td></td><td>C2</td><td>[% vol.]</td><td> 19,89</td><td> 82,206</td><td> 10,70</td><td> 11,56</td>

<td></td><td>C2H6</td><td>[% vol.]</td><td> 1,07</td><td> 0,04052</td><td></td><td></td>

<td></td><td>C4</td><td>[% vol.]</td><td> 0,01</td><td> 5,152</td><td></td><td></td>

<td></td><td>Isopentane</td><td>[% vol.]</td><td> 0,01</td><td> 0,7445</td><td></td><td></td>

<td></td><td>C6</td><td>[% vol.]</td><td> 1,44</td><td> 9,452</td><td> 0,07</td><td> 0,03</td>

<td></td><td>C3H6</td><td>[% vol.]</td><td> 0,22</td><td> 0,2034</td><td></td><td></td>

<td></td><td>C3H8</td><td>[% vol.]</td><td> 0,01</td><td> 0,009156</td><td> 12,50</td><td> 10,80</td>

<td></td><td>H2 / C2 ratio in the gas phase</td><td>[% mol./% mol.]</td><td> 3,511</td><td> 0,057733012</td><td> 0,003383</td><td> 0,000173</td>

<td></td><td>C4 / C2 in the gas phase</td><td>[% mol./% mol.]</td><td> 0,000</td><td> 0,062671824</td><td></td><td></td>

Table 17 continues

<td>Streams</td><td>Initial flow C2</td><td>[g / hour]</td><td> 68,66</td><td> 230</td><td> 2497,00</td><td> 2497,00</td>

<td></td><td>H2 flow</td><td>[N-liters / hour]</td><td> 140,42</td><td> 7,213</td><td> 4,96</td><td> 0,00</td>

<td></td><td>Flow C.₂</td><td>[g / hour]</td><td> 816,23</td><td> 856,475</td><td> 2497,00</td><td> 2497,00</td>

<td></td><td>Flow C4 (AK 3)</td><td>[g / hour]</td><td> 0,00</td><td> 199,941</td><td></td><td></td>

<td></td><td>Flow hexene</td><td>[g / hour]</td><td></td><td></td><td> 0,00</td><td> 163,44</td>

<td></td><td>Flow catalyst</td><td>[pmole Ti / hour]</td><td> 62,06</td><td> 21,2</td><td> 87,36</td><td> 61,30</td>

<td></td><td>Flow hexane</td><td>[g / hour]</td><td> 207,90</td><td> 71,02</td><td>5902 (C3), 896 (C6)</td><td>5902 (C3), 628, 3 (C6)</td>

<td>Properties the product</td><td>Powder (before confusion)</td><td>Melt flow index, I2 g / 10 min</td><td> 94</td><td></td><td> 100</td><td></td>

<td></td><td></td><td>Melt flow index, I21.6, g / 10 min</td><td></td><td> 0,38</td><td></td><td> 0,33</td>

<td></td><td></td><td>Density, g / cm³</td><td></td><td> 0,9306</td><td></td><td> 0,9285</td>

Table 18 - Product properties

<td>Example - comparative sample</td><td></td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td>

<td>Catalyst</td><td></td><td>NDA</td><td>NDA</td><td>NDA</td><td>CGC</td><td>CGC</td>

<td>I2</td><td>g / 10 minutes</td><td> 95</td><td> 0,36</td><td> 118</td><td> 119</td><td> 0,25</td>

<td>DSC</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>This</td><td>° C</td><td>No- available</td><td>not available</td><td> 125,0</td><td> 127,4</td><td> 108,8</td>

<td>Tm</td><td>° C</td><td>No- available</td><td>not available</td><td> 132,1</td><td> 135,3</td><td> 124,2</td>

<td>Crystallinity</td><td> %</td><td>No- available</td><td>not available</td><td> 85,1</td><td> 86,81</td><td> 51,49</td>

<td>GPC</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>Me</td><td></td><td> 7370</td><td> 82500</td><td> 3970</td><td> 133700</td><td> 137200</td>

<td>Mw</td><td></td><td> 26500</td><td> 389200</td><td> 44400</td><td> 355900</td><td> 345300</td>

<td>Mw / Mn</td><td></td><td> 3,6</td><td> 4,72</td><td> 11,18</td><td> 2,66</td><td> 2,52</td>

<td>RCD</td><td></td><td>no</td><td>no</td><td>no</td><td>no</td><td>Yes</td>

<td>Density</td><td>g / cm³</td><td> 0,9719</td><td> 0,9298</td><td> 0,9720</td><td> 0,9731</td><td> 0,9235</td>

PL 203 864 B1

Table 19 - Product performance

<td>Example</td><td></td><td>Attempt comparative 8</td><td>Example 9 according to the invention</td><td>Example 10 according to the invention</td><td>Example 11 according to the invention</td>

<td>Mixture</td><td> 48%/52%</td><td>NDA / NDA</td><td>CGC / NDA</td><td>NDA / CGC</td><td>CGC / CGC</td>

<td>Melt flow index</td><td></td><td></td><td></td><td></td><td></td>

<td>I5</td><td>g / 10 minutes</td><td> 0,32</td><td> 0,43</td><td> 0,27-0,27</td><td> 0,31</td>

<td>I21.6</td><td>g / 10 minutes</td><td> 8,64</td><td> 9,97</td><td> 4,11-4,09</td><td> 5,24</td>

<td>I21.6 / I5</td><td>Ratio</td><td> 27,00</td><td> 23,19</td><td> 15,22-15,15</td><td> 16,90</td>

<td>Density</td><td>g / cm³</td><td> 0,9519</td><td> 0,9528</td><td> 0,9506</td><td> 0,9505</td>

<td>RCD</td><td></td><td>No</td><td>No</td><td>Yes</td><td>Yes</td>

<td>Rheology, Bohlin rheometer viscosity, about 1 / s</td><td>Crimson</td><td> 74251</td><td> 60151</td><td> 66489</td><td> 61290</td>

<td>viscosity, about 100 / s</td><td>Crimson</td><td> 2298</td><td> 2110</td><td> 3006</td><td> 3085</td>

<td>Exponent K</td><td></td><td> 28047</td><td> 23925</td><td> 32067</td><td> 30370</td>

<td>Exponent n</td><td></td><td> 0,4817</td><td> 0,5077</td><td> 0,5304</td><td> 0,5439</td>

<td>Properties in stretching Yield point</td><td>MPa</td><td> 25,4</td><td> 25,1</td><td> 24,7</td><td> 24,6</td>

<td>Young's modulus</td><td>MPa</td><td> 1072</td><td> 1011</td><td> 946</td><td> 960</td>

<td>Young's modulus in three-point bending</td><td>MPa</td><td> 986</td><td> 910</td><td> 837</td><td> 848</td>

<td>Izod impact strength</td><td>kJ / m²</td><td> 22, 1</td><td> 17,1</td><td> 34,7</td><td> 42,7</td>

<td>Rapid crack propagation, Gc, ductile-brittle twenty</td><td>kJ / m²</td><td> 14,8</td><td> 21,4</td><td> 24,0</td><td> 38,9</td>

<td> 0</td><td>kJ / m²</td><td> 10,9</td><td></td><td></td><td></td>

<td> -5</td><td>kJ / m²</td><td> 9,6</td><td></td><td></td><td></td>

<td> -10</td><td>kJ / m²</td><td> 8,8</td><td></td><td> 10,5</td><td> 20,9</td>

<td> -15</td><td>kJ / m²</td><td> 7,5</td><td></td><td> 8,5</td><td></td>

<td> -20</td><td>kJ / m²</td><td> 6,6</td><td> 11,8</td><td> 7,6</td><td> 19,3</td>

<td> -30</td><td>kJ / m²</td><td> 6,4</td><td> 10,0</td><td></td><td> 17,3</td>

<td> -40</td><td>kJ / m²</td><td></td><td> 7,7</td><td></td><td> 12,9</td>

<td> -50</td><td>kJ / m²</td><td></td><td> 7,3</td><td></td><td> 10,4</td>

<td> -60</td><td>kJ / m²</td><td></td><td></td><td> 6,3</td><td> 10,3</td>

<td>Tdb</td><td>° C</td><td> -12</td><td> -35</td><td> -17</td><td> -45</td>

<td>PENT crack growth slowly</td><td>Minutes</td><td> 59700</td><td> 16362</td><td> &gt;110000</td><td> &gt;110000</td>

<td>GPC</td><td></td><td></td><td></td><td></td><td></td>

<td>Me</td><td></td><td> 11700</td><td> 14100</td><td> 7660</td><td> 19700</td>

<td>Mw</td><td></td><td> 198800</td><td> 271600</td><td> 233100</td><td> 218900</td>

<td>M "/ Mn</td><td></td><td> 16,99</td><td> 19,26</td><td> 30,43</td><td> 11,11</td>

<td>Mz</td><td></td><td> 797100</td><td> 2183000</td><td> 757000</td><td> 732600</td>

PL 203 864 B1

The product properties (given in Table 19) were determined in these tests as disclosed in EP 089586 and WO 01/005852, and the critical strain energy release rate was determined as described above.

From Table 19, when comparing Comparative Sample 8 with Example 9 of the invention, it is clear that switching from a broad MWD LMW component to a narrow MWD component (when the HMW component has a broad MWD) unexpectedly increases the Gc from 14.8 to 24.1 kJ / m²and the Tdb decreases from -12 ° C to -35 ° C. In addition, when comparing Examples 10 and 11 of the invention, the change from the broad MWD LMW component to the narrow MWD component (when the HMW component has a narrow MWD) increases the Gc from 24 to 38.9 kJ / m.² and lowering the Tdb from -17 ° C to -45 ° C.

As discussed above, the invention provides a novel polyethylene composition useful in the manufacture of water and gas pipes, and various other articles. The new composition has one or more of the following advantages. First, the new composition is more durable. In some cases, certain compositions provide exceptional durability. However, the increased durability is not achieved at the expense of toughness. Certain compositions exhibit both good toughness and durability. Accordingly, articles made from the new compositions should have a longer service life. Since the new composition comprises at least two components, the required properties of the composition as a whole can be achieved by adjusting the characteristics of each component, such as MWD, average molecular weight, density, comonomer distribution, etc. In this way, a desired composition can be designed by manipulation at the molecular level. Other features and additional advantages are obvious to specialists.

While the invention has been described with reference to a limited number of embodiments, the specific features of one embodiment should not be attributed to other embodiments. No single embodiment embodies all aspects of the invention. In addition, there are variants and modifications. For example, the polyethylene composition may contain a third component, in the form of an ethylene homopolymer or copolymer, which will make the overall molecular weight distribution of the composition trimodal. Likewise, a fourth, fifth, or sixth component may be added to suit the physical properties of the composition. Various additives may also be used to further improve one or more properties. In other embodiments, the composition comprises essentially a LMW component and a HMW component, as described herein. In some embodiments, the composition is substantially free of any additive that is not specifically specified. In some embodiments, the composition is substantially free of a nucleating agent. Cross-linking by physical or chemical methods can be another way of modifying the composition.