Process for the preparation of soft propylene polymer compositions

[0001] The present invention relates to a polymerization process for the preparation of soft propylene polymer compositions. The compositions obtained by this method are particularly suitable for the production of films and injection molded elements. In particular, said products have good flexibility, excellent impact properties even at low temperature, and very little chemical release. Hence, said products are particularly suitable for use in contact with food and for biomedical applications.

[0002] It is well known in the art that the presence of readily soluble xylene fraction is needed to produce soft propylene polymer compositions. However, the high content of xylene soluble part leads to large amounts of hexane extractable fractions such that soft compositions often become unsuitable in the field of food packaging.

[0003] European patent application WO 03/046021 discloses thermoplastic polyolefin compositions having good low temperature impact properties and also showing a small amount of hexane extractable fraction. Said compositions contain a propylene copolymer having a content of xylene insoluble fraction not less than 85% by weight and a propylene copolymer containing 8-40 wt. alpha-olefins and having a melt flow rate (MFR) determined according to ISO 1133 (230^aboutC, 2.16 kg) of 3- 30 g / 10 min. The above-mentioned MFR values ​​are obtained by subjecting oxidative degradation to a precursor composition having a lower MFR.

[0004] The above-mentioned compositions exhibit a low content of hexane extractable fractions, but they are not completely satisfactory with regard to softness (relatively high flexural modulus / MFR ratio) and impact properties at low and very low temperatures. On the other hand, it can be seen that the hexane soluble fraction determined on the plate increases from 5.5% to 7.4% by weight when the composition becomes softer (flexural modulus) 370 MPa in the example. 3) and the total ethylene content increases (from 8% in example 1 to 9.3% in example 3). Said compositions are produced by a sequential polymerization process involving the production of component (A) in a first gas phase polymerization apparatus comprising two polymerization zones interconnected with each other and a second step (B), in which by polymerization of monomers in a separate fluidized bed reactor is produced ethylene rich polypropylene copolymer.

[0005] The applicant has now found a method for producing a soft propylene polymer composition that exhibits an even better balance between the hexane soluble fraction and low flexural modulus. Thus, the present invention relates to a process for producing a propylene polymer composition having a flexural modulus lower than 500 MPa, a total ethylene content higher than 9%, and a xylene soluble fraction higher than 20% at room temperature, comprising at least one polymerization step carried out in a reactor for gas phase polymerization containing at least two polymerization zones interconnected with each other, wherein said method is characterized in that at least 30% by weight of said xylene soluble fraction is produced in a polymerization step carried out in a gas phase polymerization reactor comprising at least two polymerization zones interconnected with each other.

[0006] Indeed, it has surprisingly been found that the compositions so prepared, even if they are extremely soft, have a very low content of hexane extractable fractions.

Preferably, the compositions prepared according to the method of the invention have a flexural modulus lower than 500 MPa, preferably lower than 450 MPa, most preferably lower than 400

MPa. The content of xylene soluble fraction at room temperature is more than 30% by weight, specifically ranging from more than 30% to 40% by weight.

[0008] The total ethylene content is higher than 9%, preferably higher than 10%, and more preferably ranges from 10 to 30% by weight.

[0009] The intrinsic viscosity of the xylene soluble fraction determined on the reactor type polymer composition ranges from 0.5 dl / g to 5.0 dl / g, preferably between 1.0 to 4.0 dl / g, and more preferably from

2.0 to 4.0 dl / g.

[0010] The compositions obtained according to the method of the invention can be obtained as reactor type compositions with a melt flow rate according to ISO 1133 (230^aboutC, 2.16 kg) ranging from 0.1 to 50 g / 10 min. Preferably they are obtained with an MFR of less than 5 and more preferably in the range of 0.5-4 g / 10 min. Then, if needed, they can be cracked / degraded according to known technologies to obtain the final MFR value suitable for the chosen application. Chemical degradation of the polymer (cracking) is carried out in the presence of free radical initiators such as peroxides. Examples of radical initiators that can be used for this purpose are 2,5-dimethyl-2,5-di (tert-butyl dioxy) hexane and dicumyl peroxide. The degradation treatment is carried out by using appropriate amounts of free radical initiators and preferably takes place in an inert atmosphere, such as a nitrogen atmosphere. Methods, apparatus and operating conditions known in the art may be used to carry out such an operation.

[0011] The MFR after degradation may be in the range from 2 to 40 g / 10 min and preferably from 4 to 30 g / 10 min.

[0012] The propylene copolymers thus obtained have excellent impact resistance according to

Izod. Samples do not crack at 23 when tested according to ISO 180 / 1A^aboutC. When testing at 0^aboutC impact resistance ranges from 10 to 40 KJ / m²while in -20^aboutC it is from 5 to 10 ₂

KJ / m², thus showing elasticity even at low temperatures. It is noteworthy that softness and impact resistance are revealed in the presence of a very small amount of extractable hexane fractions, which are determined on the plate, are lower than 8% and preferably lower than 7% by weight. When the content of extractable fractions with hexane is determined on the film (100 mm) the value is even lower than 6% by weight.

[0013] Typically, the weight ratio between the xylene soluble fraction and the hexane extractable fraction (specified on the film) is greater than 4, preferably greater than 5, and more preferably greater than 6, even in agreement with the amount of xylene soluble fraction greater than 30 wt. and a total ethylene content greater than 10%. This feature allows the use of soft compositions even in contact with food.

[0014] As explained above, the propylene copolymer compositions are prepared by a method comprising at least one polymerization step carried out in a gas phase polymerization reactor comprising at least two polymerization zones interconnected with each other, said method being characterized by that at least 30% by weight of said xylene soluble fraction is produced in a polymerization step carried out in a gas phase polymerization reactor comprising at least two polymerization zones interconnected with each other. Preferably, at least 50% and more

Preferably at least 70% by weight of said xylene soluble fraction is produced in a gas phase polymerization reactor containing at least two polymerization zones interconnected with each other.

[0015] Although it is possible to prepare the propylene copolymer composition disclosed above in a sequential process in which at least one polymerization step is carried out in a gas phase polymerization reactor containing at least two polymerization zones interconnected with each other, and the other polymerization step is carried out in a conventional liquid phase polymerization reactor or a conventional fluid phase or mixed bed gas phase polymerization reactor, preferably the entire composition is prepared in one or more polymerization stages, all of which are carried out in a polymerization reactor in a gas phase comprising at least two polymerization zones interconnected with each other. In particular, it is preferred that the entire fraction of the xylene soluble polymer composition is produced in this type of reactor. The polymerization process carried out in a gas phase polymerization reactor containing at least two polymerization zones interconnected with each other is described in European Patent EP 782587.

[0016] The process is carried out in the first and second polymerization zones, interconnected, into which propylene and ethylene or propylene and alpha-olefins are introduced, in the presence of a catalytic system and from which the polymer produced is discharged. Growing polymer particles flow through the first of these polymerization zones (ascending zone) under rapid fluidization conditions, leave said first polymerization zone and enter the second of said polymerization zones (precipitation zone), through which they flow in a concentrated form under the influence of gravity, leave said a second polymerization zone and are reintroduced into said first polymerization zone, thus establishing polymer circulation between these two polymerization zones. Generally, the conditions for rapid fluidization in said first polymerization zone are set by introducing a gaseous monomer mixture below the point for reintroducing the growing polymer into said first polymerization zone. The rate of transporting gas to the first polymerization zone is higher than the rate of transport under operational conditions and is usually between 2 and 15 m / s. In the second polymerization zone, where the polymer flows in concentrated form under the action of gravity, higher solids density values ​​are obtained that reach the density of the polymer in bulk; a positive pressure difference can be obtained along the flow direction so that it becomes possible to reintroduce the polymer into the first reaction zone without the help of mechanical means. In this way, a "loop" circulation is created, which is determined by the pressure balance between the two polymerization zones and by the pressure drop introduced into the system. Optionally, one or more inert gases, such as nitrogen or aliphatic hydrocarbons, are maintained in the polymerization zones in amounts such that the sum of the inert gas partial pressures is preferably between 5 and 80% of the total gas pressure.

Operating parameters, such as, for example, temperature, are those which normally occur in a gas phase polymerization process, for example between^aboutC a 120^aboutC. The process can be carried out at an operating pressure between 0.5 and 10 MPa, preferably between 1.5 and 6 MPa. Preferably, the various catalyst components are fed to the first polymerization zone at any point in said first polymerization zone. However, they can also be administered at any point in the second polymerization zone. Molecular weight regulators known in the art, particularly hydrogen, can be used to regulate the molecular weight of the growing polymer.

[0017] By using the means described in WO 00/02929 it can be completely or partly prevented from the entry of the gas mixture present in the ascending zone into the downfall zone; in particular, this is preferably obtained by introducing into the downfall zone gas and / or a liquid mixture having a composition other than the gas mixture located in the ascending zone. According to a particularly preferred embodiment of the present invention, introduction into the downfall zone of said gas and / or liquid mixture having a composition different from the gas mixture present in the ascension zone is effective in preventing the second mixture from entering the downfall zone. Thus, it is possible to obtain two interconnected polymerization zones having different monomer compositions and hence capable of producing polymers with different properties.

[0018] The above feature is particularly important for the production of the propylene copolymer according to the invention, because it allows to keep different amounts of ethylene in these two zones, which in turn in the less-rich ethylene zone, enables the production of significant amounts of xylene insoluble propylene copolymer fraction, and in the rich zone in ethylene, significant amounts of xylene soluble propylene copolymer fraction.

[0019] Typically, the ethylene rich polymerization zone is the riser zone, where the molar concentration of ethylene (expressed as the molar ratio between ethylene and the total molar amount of monomers) when the entire propylene copolymer composition is produced in a gas phase polymerization reactor containing two zones polymerizations interconnected with each other are in the range from 0.1 to 0.3, preferably from 0.12 to 0.20; in the precipitation zone, due to the barrier effect provided by the gas and / or liquid introduction described above, the gas phase composition is less rich in ethylene and generally ranges from 0.010.05, preferably from 0.02 to 0.04. The ratio between the ethylene content in the ascending zone and the precipitation zone is typically higher than 5, and more typically higher than 6.

[0020] If an additional step is carried out in another type of reactor, it is particularly preferably carried out in a conventional fluid phase gas phase reactor. Preferably this step is carried out as a second step. The polymerization mixture is discharged from the precipitation zone into a gas-solid separator, and then introduced into the fluidized-bed gas phase reactor operating under conventional temperature and pressure conditions.

[0021] Each polymerization step is carried out in the presence of a highly stereospecific catalyst based on a transition metal compound. Preferably it is a Ziegler-Natta heterogeneous catalyst.

Ziegler-Natta catalysts suitable for preparing the propylene polymer compositions of the invention contain a solid catalyst component comprising at least one titanium compound having at least one titanium-halogen bond and at least one electron-donor compound (internal donor), both applied to a carrier with magnesium chloride. Ziegler-Natta catalyst systems additionally contain an organo aluminum compound as an important cocatalyst and, optionally, an external electron donor compound.

[0022] Suitable catalyst systems are described in European patents EP 45977, EP 361494, EP

728769, EP 1272533 and international patent application WO 00/63261.

Preferably, the solid catalyst component comprises Mg, Ti, halogen and an electron donor selected from succinates of formula (I):

EP 2 158 234 B1 ο

r₃ II

Κ.-ΥΎ '' *² (AND)

ΎσΥ

R1 II Ο in which R1 and R2, the same or different, are a linear or branched C1-C20-alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group optionally containing heteroatoms; the same or different R3 to R6 radicals are hydrogen or a linear or branched C1-C20-alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms and R3 to R6 radicals that are attached to the same carbon atom , they can be joined together to form a ring.

[0024] R1 and R2 are preferably a C1-C8-alkyl, cycloalkyl, aryl, arylalkyl and alkylaryl group. Particularly preferred are compounds in which R1 and R2 are selected from primary alkyls, and in particular from branched primary alkyls. Examples of suitable R1 and R2 groups are methyl, ethyl, n-propyl, n-butyl, isobutyl, neopentyl, 2-ethylhexyl. Ethyl, isobutyl and neopentyl are particularly preferred.

[0025] One preferred group of compounds described by formula (I) is a group in which R3 to R5 are hydrogen and R6 is a branched alkyl, cycloalkyl, aryl, arylalkyl and alkylaryl radical having 3 to 10 carbon atoms. Another preferred group of compounds encompassed by formula (I) is a group in which at least two radicals from R3 to R6 are other than hydrogen and are selected from a linear or branched C1-C20-alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms. Particularly preferred are compounds in which two radicals other than hydrogen are connected to the same carbon atom. Furthermore, compounds in which at least two radicals other than hydrogen are attached to different carbon atoms, i.e. R3 and R5 or R4 and R6, are also particularly preferred. [0026] A particularly preferred catalyst, in addition to Mg, Ti and halogen, contains an electron donor selected from phthalic acid esters disclosed in EP 45977, and in particular either diisobutyl phthalate or dihexyl phthalate or diethyl phthalate and mixtures thereof.

[0027] According to a preferred method, a solid catalyst component can be produced by reacting a titanium compound of formula Ti (OR) n-yXy, where n is the valence of titanium and y is a number between 1 and preferably TiCl₄, with magnesium chloride derived from the adduct of the formula MgCl ^ pROH, where p is a number between 0.1 and 6, preferably from 2 to 3.5, and R is a hydrocarbon radical having 1-18 carbon atoms. The adduct may be suitably produced in spherical form by mixing alcohol and magnesium chloride in the presence of an inert hydrocarbon immiscible with the adduct, under stirring at the melting point of the adduct (100 - 130^aboutC). Then, the emulsion is quickly quenched, which causes the solidification of the product in the form of spherical particles. Examples of spherical adducts produced according to this procedure are described in US 4,399,054 and US 4,469,648. The adduct thus obtained may be directly reacted with a Ti compound or may be previously subjected to thermally controlled alcohol removal (80 -130^aboutC) so as to obtain an adduct in which the number of alcohols is generally less than 3, preferably from 5

Between 0.1 and 2.5. The reaction with the Ti compound can be carried out by suspending the adduct (de-alcoholized or as such) in cold TiCl4 (usually at 0).^aboutC); the mixture is heated to 80-130^aboutC and kept at this temperature for 0.5-2 hours. TiCl4 treatment can be carried out once or many times. The internal donor can be added during treatment with TiCl4 and treatment with the electron-donor compound can be carried out once or repeatedly. In general, the internal electron donor compound as well as the particular succinate salt of formula (I) is used in a molar ratio with respect to MgCl2 of from 0.01 to 1, preferably from 0.05 to 0.5. The preparation of the catalyst component in spherical form is described, for example, in European Patent Application EP-A-395083 and International Patent Application WO 98/44001. Solid catalyst component obtained in accordance with₂ using a higher method, it has a specific surface area (BET method) generally between 20 and 500 m²/ g, and preferably between 50 and 400 m²/ g and a total porosity (BET method) higher than 0.2 cm³/ g, preferably between 0.2 and 0.6 cm³/ G. Porosity (by the Hg method), due to pores with a radius of up to 10,000 A, is generally in the range of 0.3 to 1.5 cm³/ g, and preferably from 0.45 to 1 cm³/ G.

[0028] The organoaluminium compound is preferably an alkylaluminium compound selected from trialkylaluminum compounds, such as, for example, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-octylinealuminum. It is also possible to use mixtures of trialkylaluminum compounds with aluminum halides, alkylaluminum hydrides or alkylaluminium sesquilides such as AlEt2Cl and Al2Et3Cl3.

[0029] Preferred compounds that are external electron-donors include silicon compounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines, heterocyclic compounds, and in particular 2,2,6,6-tetramethylpiperidine, ketones and 1,3-diethers. Silicon compounds of formula Ra are another class of preferred external electron-donor compounds⁵rb⁶Si (OR⁷) c, in which a and b are integers from 0 to 2, c is

6 7 is an integer from 1 to 3, and the sum (a + b + c) is 4. R⁵, R⁶ and R⁷ are alkyl, cycloalkyl or aryl radicals having 1-18 carbon atoms, optionally containing heteroatoms. Particularly preferred are methylcyclohexyl-dimethoxysilane, diphenyldimethoxysilane, methyl-tert-butyldimethoxysilane, dicyclopentyl dimethoxysilane, 2-ethylpiperidinyl-2-t-butyldimethoxysilane and 1,1,1-trifluoropropyl-2-ethyl-1-ethyl-1-ethyl-1-ethyl-dimethyl-dioxyl dimethoxysilane. The compound which is an external electron donor is used in such an amount as to obtain a molar ratio between the organo aluminum compound and said external electron donor compound from 0.1 to 500.

[0030] The catalyst system can be formed directly in the reactor by feeding the separate components of a solid catalyst component, an alkylaluminum compound as a cocatalyst and an external electron donor as an activator, or it can be formed earlier by mixing the components in a separate reactor (pre-contact) and then introducing the system thus obtained catalyst to the reactor. According to another preferred option, the pre-formed catalyst system is contacted with a small amount of olefins to produce a pre-polymerized catalyst, which is then sent to the main polymerization reactor. The molecular weight of the propylene polymer composition can be controlled by the use of known regulators, such as hydrogen.

[0031] The propylene copolymer compositions obtained by the process of the present invention may then be supplemented with additives commonly used in the polyolefin field, such as antioxidants, light stabilizers, crystallization nuclei, antacids, dyes and fillers. [0032] The main use of the propylene polymer composition according to the invention includes the production of films, particularly soft blown films and molded articles, particularly injection molded parts6

EP 2 158 234 B1. Injection molded products containing the propylene polymer compositions of the invention exhibit good flexibility and excellent low temperature impact properties. Due to the low proportion of the extractable fraction in hexane in the polyolefin compositions of the invention, the films and injection molded articles obtained therefrom are particularly suitable for food applications.

The following examples are given to illustrate and not to limit the present invention.

Examples

Data on propylene polymer materials were obtained according to the following methods:

Xylene soluble fraction [0033] 2.5 g of polymer and 250 ml of o-xylene were introduced into a glass flask equipped with a condenser and a magnetic stirrer. Within 30 minutes, the temperature was raised to the boiling point of the solvent. The solution thus obtained was then kept under reflux with stirring for a further 30 minutes. The closed flask was then kept for 30 minutes in an ice-water bath and a thermostated water bath in 25^aboutC also for 30 minutes. The solid thus obtained was filtered off on fast-drying filter paper, and then the filtered liquid was divided into two 100 ml portions. One 100 ml portion of the filtered liquid was poured into a previously weighed aluminum container, which was then heated on a hot plate under a stream of nitrogen to remove the solvent by evaporation. The container was then kept in the oven at 80^aboutC under vacuum until constant weight. The residue was weighed to determine the percentage of xylene soluble polymer.

Comonomer content (C2)

By means of infrared spectroscopy (IR) [0034] The comonomer content of component B was determined on the precipitated "amorphous" polymer fraction. The precipitated "amorphous" fraction was prepared as follows: 200 ml of acetone was added to one portion of 100 ml of filtered liquid obtained as described above with vigorous stirring. The precipitation must be complete, which is confirmed by the clear separation of the solid and solution. The solid thus obtained was filtered off on a metal mesh and dried in a vacuum oven at 70^aboutC, up to constant weight.

Molar ratio of feed gases [0035] Determined by gas chromatography

Melt flow rate (MFR) [0036] Determined according to ISO 1133 (230^aboutC, 2.16 kg)

Intrinsic viscosity [0037] Determined in tetrahydronaphthalene at 135^aboutC

EP 2 158 234 B1

Modulus of flexural strength [0038] Determined according to ISO 178

Stress at yield and breaking strength [0039] Determined according to ISO 527

Elongation at yield and break [0040] Determined according to ISO 527

Impact resistance according to IZOD [0041] Determined according to ISO 180 / 1A

Transition temperature ductile / brittle (D / B) [0042] According to this method, the biaxial impact resistance was determined by impact with an automatic computerized impact hammer.

[0043] Round test specimens were obtained by cutting with a round hand punch (diameter 38 mm). They were conditioned for at least 12 hours at 23^aboutC at 50% relative humidity and then placed in a thermostated bath at test temperature for 1 hour. When hitting with a hammer (5.3 kg, a semi-circular punch with a diameter of 1/2 ") a force-time curve was recorded on a round sample resting on an annular support. The machine used was apparatus type CEAST 6758/000 model No. 2. The D / B transition temperature is the temperature at which 50% of the samples undergo brittle fracture when subjected to the impact test described above.

[0044] D / B measuring plates 127x127x1.5 mm were prepared according to the following method.

[0045] The injection press is a Negri Bossi ™ (NB90) machine with a closing force of 90 tonnes. The mold is a rectangular plate (127x127x1.5 mm) [0046] The main process parameters are listed below:

Back pressure (bars):

Injection time (s):

Maximum injection pressure (MPa): Hydraulic injection pressure (MPa): First pressing pressure (MPa): First pressing time (s):

6-3

4±2

Secondary hydraulic pressure (MPa): 3 ± 2

Second pressing time (s): Cooling time (s): Mold temperature (^aboutC):

[0047] The melt temperature is in the range of 220 - 280^aboutC.

Fraction extractable with hexane [0048] The proportion of extractable with hexane was determined according to the modified FDA method (federal registration, title 21, chapter 1 part 177, section 1520, p. Annex B) on a molded polymer in the form of a plate or foil 100 mm. The plate was formed by pressing, while the film was prepared by extrusion.

Melting point, melting enthalpy and crystallization temperature [0049] Determined by DSC with temperature changes 20^aboutC per minute.

Examples 1-5 [0050] The Ziegler-Natta catalyst was produced according to example 5, lines 48-55 of European Patent EP 728769. Triethylaluminum (TEAL) was used as the cocatalyst, and dicyclopentyl dimethoxysilane as the external donor, in the weight proportions indicated in Table 1 .

[0051] The propylene copolymer compositions of the examples were produced in a single gas phase polymerization reactor containing two polymerization zones interconnected with each other, an ascending zone and a precipitation zone, as described in European Patent EP 782587 and WO 00/02929. Triethylaluminum (TEAL) was used as the cocatalyst, and dicyclopentyl dimethoxysilane as the external donor in the weight proportions indicated in Table 1. The operating conditions are shown in Table 1.

[0052] The polymer particles leaving the polymerization step were steamed to remove unreacted monomers and dried.

[0053] The propylene polymer compositions were supplemented with the additives indicated in Table 3 and extruded in a Berstoff twin screw extruder (L / D = 33) under the following operating conditions:

Supply section temperature: Melting point: Nozzle section temperature: Flow rate: Rotation speed:

190-210^aboutC

240^aboutC

230^aboutC 16 kg / h

250 revolutions per minute (rpm) [0054] The properties measured for the samples are summarized in Table 3.

Example 6 [0055] The process of example 4 was repeated with the difference that the polymer composition leaving the polymerization reactor containing two polymerization zones interconnected with each other was sent to a conventional fluidized bed reactor, where an additional ethylene propylene copolymer was produced. The polymer particles leaving the polymerization step were steamed to remove unreacted monomers and dried.

[0056] The conditions used in said conventional fluidized bed polymerization reactor and the characteristics of the final composition of the reactor are given in Table 2. A summary of the properties of the pre-cracking composition is given in Table 3.

Table 1

<td>EXAMPLE</td><td></td><td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td>

<td>TEA / donor</td><td>g / g</td><td> 4</td><td> 5</td><td> 4</td><td> 5</td><td> 4,1</td>

<td>TEA / catalyst</td><td>g / g</td><td> 5,7</td><td> 5</td><td> 5</td><td> 72</td><td> 6,2</td>

<td>Temperature</td><td>^ATC</td><td> 65</td><td> 65</td><td> 65</td><td> 65</td><td> 65</td>

<td>Pressure</td><td>hypertension bars</td><td> 22</td><td> 22</td><td> 22</td><td> 22</td><td> 22</td>

<td>H2 / C3 in the ascending zone /</td><td>mol / mol</td><td> 0,01</td><td> 0,016</td><td> 0,016</td><td> 0,018</td><td> 0,017</td>

<td>rainfall zone</td><td></td><td> 0,002</td><td> 0,004</td><td> 0,004</td><td> 0,003</td><td> 0,003</td>

<td>C2^-/ C2^-+ C3^- in the ascending zone</td><td>mol / mol</td><td> 0,14 0,028</td><td> 0,14 0,027</td><td> 0,11 0,018</td><td> 0,141 0,026</td><td> 0,145 0,029</td>

<td>Rising / falling zone separation</td><td>w.</td><td> 30/70</td><td> 35/65</td><td></td><td> 30/70</td><td> 30/70</td>

<td>MFR</td><td>g / 10 '</td><td> 0,2</td><td> 0,43</td><td> 0,41</td><td> 0,66</td><td> 0,68</td>

<td>C2 (A)</td><td>wt%</td><td> 11</td><td> 11,4</td><td> 11,4</td><td> 9,70</td><td> 10,3</td>

<td>Xylene soluble fraction, XS</td><td>wt%</td><td> 34,7</td><td> 36,9</td><td> 35,7</td><td> 33,7</td><td> 36,6</td>

<td>Intrinsic viscosity of the xylene soluble fraction, IVXS</td><td>dl / g</td><td> 3,28</td><td> 2,76</td><td> 2,65</td><td> 2,49</td><td> 2,53</td>

Table 2

<td>EXAMPLE</td><td></td><td> 6</td>

<td>Temperature</td><td>^ATC</td><td> 85</td>

<td>C2^-/ C2^-+ C3^-</td><td>mol / mol</td><td> 0,16</td>

<td>MFR</td><td>g / 10 '</td><td> 0,15</td>

<td>C2 (total)</td><td>wt%</td><td> 10,8</td>

<td>XS</td><td>wt%</td><td> 39,7</td>

<td>IVXS</td><td>dl / g</td><td> 3,7</td>

Table 3

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

<td>Granule formulation</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>AO B215 0</td><td>wt%</td><td> 0,15</td><td> 0,15</td><td> 0,15</td><td> 0,15</td><td> 0,15</td><td> 0,15</td>

<td>Calcium stearate</td><td>wt%</td><td> 0,05</td><td> 0,05</td><td> 0,05</td><td> 0,05</td><td> 0,05</td><td> 0,05</td>

<td>Luperox 101</td><td>wt%</td><td>given higher</td><td>given higher</td><td>given higher</td><td>given higher</td><td>given higher</td><td>given higher</td>

EP 2 158 234 B1

<td>Characteristic</td><td colspan="2"></td><td></td><td colspan="2"></td><td></td><td></td>

<td>Melt flow rate alloy</td><td></td><td> 8,1</td><td> 5,3</td><td> 11,6</td><td> 6,5</td><td> 5,5</td><td> 6,2</td>

<td>Modulus of strength at bending</td><td>MPa</td><td> 260</td><td> 260</td><td> 304</td><td> 293</td><td> 300</td><td> 210</td>

<td>Stress at the elastic limit</td><td>MPa</td><td> 11,1</td><td> 11</td><td> 11,2</td><td> 12,4</td><td> 12,1-</td><td> 10,5</td>

<td>Elongation at the elastic limit</td><td> %</td><td> 22,5</td><td> 23</td><td> 22</td><td> 21,3</td><td> 21,1</td><td> 25,4</td>

<td>Tension at break</td><td>MPa</td><td> -&gt;9,9</td><td> &gt;20,3</td><td> &gt;22,9</td><td> &gt;21,7</td><td> 19,6-</td><td> 23</td>

<td>Elongation at break</td><td> %</td><td> &gt;600</td><td> &gt;595</td><td> &gt;600</td><td> &gt;600</td><td> 520</td><td> &gt;650</td>

<td>Izod in 23^aboutC</td><td>kJ / m²</td><td>does not crack</td><td>does not crack</td><td>does not crack</td><td>does not crack</td><td>does not crack</td><td>does not crack</td>

<td>Izod at 0^ATC</td><td>kJ / m²</td><td> 34,7</td><td> 32</td><td> 14,5</td><td> 13,5</td><td> 14,2</td><td> 38</td>

<td>Izod in -20^aboutC</td><td>kJ / m²</td><td> 6,7</td><td> 8,4</td><td> 7,7</td><td> 4,4</td><td> 5,1</td><td> 9,5</td>

<td>D / B transition temperature</td><td>^ATC</td><td> 1,1</td><td></td><td> -41,4</td><td> 5</td><td></td><td> -7</td>

<td>Extractable fraction</td><td> %</td><td> -</td><td> -</td><td> 6</td><td> 6</td><td> -5</td><td> 7</td>

<td>add hexane on a plate and on</td><td></td><td></td><td></td><td> 5</td><td> 5</td><td> 4</td><td> 6</td>

<td>foil</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>Melting temperature</td><td>^ATC</td><td> 141</td><td> 139</td><td> 141</td><td> 141</td><td> 138</td><td> 140</td>

<td>Enthalpy of melting</td><td>J / g</td><td> 50</td><td> 45</td><td> 53</td><td> 50</td><td> 46</td><td> -</td>

<td>Crystallization temperature</td><td>^ATC</td><td> 90</td><td> 88</td><td> 91</td><td> 88</td><td> 90</td><td> -</td>

<td colspan="8">AO B215 - a mixture of Irgafos 168 and Irganox 1010 2: 1 CaSt calcium stearate</td>