Catalysts and process for the polymerization of olefins

<td>POLAND REPUBLIC CHINA</td><td>PATENT DESCRIPTION</td><td> 72704</td>

<td></td><td>Additional Patent for patent Reported: November 22, 1969 (P. 137051) Priority: November 25, 1963 Italy</td><td>Kl. 39b⁴, 1/28 MIO »C08f 1/28</td>

<td>OFFICE PATENTOWT</td><td>The application was announced: 31.03.1973</td><td></td>

<td>PRL</td><td>Patent description published: 30.12.1974 j</td><td></td>

Creators of the invention: Adolfo Mayr, Paolo Galii, Ermanno Susa, Giovanni di Druscp, Ettore Giachetti

Patent holder: Montecatini Edison SpA, Milan (Italy)

A method for producing the olefin polymerization catalyst

The present invention relates to a process for the preparation of an olefin polymerization catalyst at a temperature of -80 ° C to 2Q9 ° C, at equal or higher than atmospheric pressure, optionally in the presence of an inert liquid and in the presence of a ₅polymer molecular weight path.

Methods for obtaining olefin polymerization catalysts are known, which rely on the reaction of titanium compounds, e.g. titanium tetrahalides, with hydrides or organometallic metal compounds ₁₀thallium I, II and III groups of the Periodic Table of Elements at atmospheric pressure or slightly above atmospheric at a temperature from -80 ° C to 200 ° C.

From British Patent No. 904,510 ₁₅ the method of obtaining olefin polymerization is known, which is the reaction product of an organometallic compound of metals of groups I to III of the periodic table with elements with an inorganic salt of the MgCL type₂, coated on the surface &amp; with a layer of transition metal halide with a molecular thickness. The amount of transition metal halide deposited on the support does not exceed 1% by weight of the support itself.

According to the British patent specification, the transition metal compound cannot be used in an amount greater than the above-mentioned because there is a significant decrease in the activity of the catalyst. This is because, according to the said patent, inorganic salts are not subjected to treatment which leads to their transformation into catalyst carriers with high activity, even in the presence of large amounts of transition metal compound deposited on them. Due to the low amount of supported catalytically active compound, according to the said British patent, very large amounts of supported catalyst should be used to obtain a practically useful polymer yield. However, the use of such large amounts of supported catalyst creates a need to clean the polymer from catalyst residues after polymerization.

Surprisingly, it has been found that catalysts for polymerization reactions with favorable properties, in particular with very high activity, which in many cases eliminates the purification of the polymer by activating with the use of hydride or the organometallic compound of metals of groups I-III of the periodic table of the reaction product obtained by Ti tetrahalide treatment especially TiCl₄a carrier, being or containing anhydrous Mg or Zn halide in active form, previously prepared or obtained during the manufacture of the catalyst.

Anhydrous Mg or Zn halides in active form are characterized by the following properties: in the X-ray spectrum of their powders, the maximum intensity diffraction line,

704

704 appearing in the spectrum of inactivated Mg and Zn halogens, it becomes less intense, and in its place appears a more or less expanded halo rim, and their specific surface is above 3 m²/ g, preferably 10 m²/ G.

Very active forms of Mg and Zn halides are characterized by the fact that in their X-ray spectrum there is an expansion of the diffraction line with maximum intensity and / or they have a specific surface value above 15 m²/ G.

In the case of anhydrous Mg chloride, the X-ray spectrum of many of its active forms is characterized by the fact that the diffraction line appearing at distances in the crystal lattice (d) of 2.56A, which is the most intense in the diffraction spectrum of normal MgCl₂, it becomes less intense and in its place an extended halo border appears, which corresponds to distances (d) in the crystal lattice of 2.80-3.25A. Similarly, the X-ray spectrum of many active forms of MgBr₂which with normal MgBr₂ shows a diffraction line for d-2.93A, becomes less intense and an expanded halo border appears in place of the diffraction line corresponding to d = 2.80-3.25A. The supported catalysts of the invention can be obtained in a variety of ways, e.g., previously activated anhydrous Mg or Zn anhydrous with four Ti halides can be treated at room temperature for sufficient time to bind at least a portion of the Ti compound on the support.

The treatment can preferably be carried out by introducing Ti tetrahalide into a suspension of activated anhydrous Mig or Zn halide in an inert solvent and evaporation of the solvent after completion of the action. In this process, the amount of Ti tetrahalide is preferably 0.1-5% by weight relative to the Mg or Zn halide.

The preferred method for obtaining a supported catalyst component is to mill anhydrous Mg halide Zn in the conditions given below in the presence of Ti tetrahalide preferably introduced in an amount of less than 10% relative to the carrier.

In addition, it has been found that a supported catalyst component can also be obtained by heating anhydrous Mg or Zn halide in an inactive form with Ti tetrahalide, especially TiCl₄, introduced in excess relative to the anhydrous halide at a relatively high temperature, generally above 70-80 ° C, followed by cooling the mixture and separating the Mg or Zn halide from it. The preparation of the pre-activated Mg and Zn halide can be carried out in various ways, for example by mechanical treatment as well as milling, anhydrous Mg or Zn halide over time under the conditions in which the active Mg and Zn halides are formed.

The milling is preferably carried out in a ball mill without organic solvents. The machining time depends essentially on the efficiency of the milling device. For example, in a centrifugal mill with porcelain grinding balls it takes about 1 hour. Shorter milling times are achieved in mills with particularly high milling efficiency, e.g. in vibrating ball mills. These milling process conditions are used to activate Mg or Zn halides without the presence of Ti tetrahalide, they can also be used when activated in the presence of Ti tetrahalide. According to another variation of the method, very active forms of Mg and Zn halides can be obtained by decomposing in an known manner an organometallic compound of the formulas R MgX and RZnX, in which R is a hydrocarbon radical, e.g. an alkyl or aryl radical, X is a halogen atom or by the reaction of the above-mentioned organometallic compounds with a stoichiometric or more halogen compound, e.g. with anhydrous hydrogen chloride gas. Another useful method for obtaining very active Mg and Zn halides is to dissolve the halides in an organic solvent, e.g. alcohol, ether or amine, fast evaporation of the solvent and heating of the halide under reduced pressure at a temperature above 100 ° C, preferably 100-400 ° C. In this way, anhydrous MgCl is obtained₂ in active form, from its solutions with CH₈OH. The catalyst prepared according to the invention contains the Ti compound, i.e. the active compound, in a carrier-related form, optionally in the form of a separated physical phase in an amount from very low, e.g. 0.01% by weight, and very high up to 20% by weight. This amount is preferably 0.1-5% by weight relative to the Mg or Zn halide.

In the process of the invention, the product obtained by treating Ti tetrahalide, preferably TiCl, is reacted₄ anhydrous Mg or Zn halide under conditions whereby the halide is converted into the active form or by treatment with a pre-activated Mg or Zn halide with a metal hydride or organometallic compound of groups I-III of the Periodic Table which is preferably selected from the following compounds A1 (C₂H₈)₈, A1 (C₂H₅)₂C1, Al (iC₄H₉)₈, Al (iC₄H₉)₂Cl, Al (CaH₅)₈cl₈, A1 (C₂H₈)₂H, Al (iC₄-H₉)₂H, Al (C.₂H₅)₂Br, Li-Al (iC₄H₉)₄, LiC₄H₉, Mg (C.₂-H₅)₂. The molar ratio of organometallic compound Ti tetrahalide is not determined. In the case of ethylene polymerization, the Al / Ti molar ratio is preferably 50-1000. The catalysts obtained according to the invention are preferably used for the polymerization of ethylene and mixtures thereof with alpha-olelines and / or diolefins. In addition, good results, especially polymer yield, can be obtained by polymerizing alpha-olefins e.g. propylene, butane-1 etc. The polymerization is carried out in a known manner in the liquid phase in inert solvents or without solvents, or in a gas phase.

The polymerization temperature is maintained between -80 ° C and + 200 ° C, preferably 50-100 ° C, atmospheric or reduced pressure. The molecular weight of the polymer can be controlled in a known manner, e.g. by carrying out the reaction in the presence of an alkyl halide or organometallic Cd and Zn compounds or hydrogen. As is known, the use of such molecular weight regulators results in a significant reduction of the catalytic activity of known Ziegler type catalysts obtained from a transition metal compound and an organometallic compound of Group I-III metals. It has been found that the substances used to regulate the molecular weight significantly influence the catalytic activity of the catalysts produced according to the invention.

For example, in the polymerization of ethylene, the molecular weight of the polymer can be adjusted to practically useful values ​​that correspond to intrinsic viscosity values ​​measured in tetralin at 135 ° C, in the range 1.5-3dl / g, but the catalyst yield in the polymer does not reach the amount at which the polymer should be purified of catalyst admixtures after polymerization.

The polyethylene thus obtained is essentially a linear, highly crystalline polymer with a specific gravity of 0.96 g / cm² or higher,&gt; characterized by workability, especially suitability for injection molding, which is very high, generally higher than polyethylene obtained with known Ziegler type catalysts. The Ti content is generally lower, less than 20 parts / million by weight.

The invention is illustrated by the following examples, without limiting its scope. Unless otherwise specified, the percentages in the examples are weight percentages.

Example I. To a centrifugal mill with 330 ml capacity, equipped with 4 porcelain balls, two with a diameter of 31.9 mm, the other two with a diameter of 40.9 mm, 48 g of anhydrous MgCl, with a specific surface area of ​​1 m²/ g and 8 g TiCl₄ and milled for 2 hours. Analysis of the milled product showed a content of 2.7% Ti and 72% Cl, the specific surface area was 20 m². *

0.06 g of milled product was taken for the ethylene polymerization test, which was carried out under the following conditions: into an autoclave made of stainless steel, with a capacity of 1.8 1 and purified with nitrogen, 1000 ml of technical heptane was introduced, followed by 2 g of Al (iC₄H_e)₈. The temperature was raised to 75^QC, then 0.06 g of ground product dispersed in 50 ml of n-heptane was introduced at this temperature and immediately after that 3 atm of hydrogen was introduced.

10 atm of ethylene with the temperature rising to around 85 ° C. Constant pressure was maintained and ethylene was fed continuously at this pressure. After hours, the suspension was discharged from the autoclave, the polymer was filtered off and dried under reduced pressure at 106 ° C. 195 g polyethylene with an average viscosity of 2.5 dl / g measured was obtained. in tetralin at 135 ° C. The yield in polymer reached 12-1008 gfe Tt

Example II 7.3 g of anhydrous MgClf. described in Example 1 and 0.5178 g TiCl₄ milled for 1 hour in the ball mill described in Example L The content of Ti in the ground product was 1.4%, the specific surface area of ​​the product was 15 m²/ G. 0.049 g of this ground product was introduced into the ethylene polymerization reaction under the conditions given in Example 1. After 4 hours, 395 g of polymer was obtained having an intrinsic viscosity of 2.5dl / g measured in tetralin at 135 ° C. The yield in polymer amounted to 570000 g / g of Ti.

Example III. 25 g of the anhydrous MgClt described in Example 1 was milled for 3 hours in the ball mill given in Example I. The specific surface of the milled product was 22 m * / g. Into a 258 ml flask equipped with a stirrer, 10 g of ground product, 50 ml of n-heptane and 0.590 g of TiCl were introduced.₄. The suspension was stirred for 1 hour at room temperature, then the solvent was evaporated. The solid product thus obtained contained 1% Ti. 0.133 g of this product was used in the ethylene polymerization reaction carried out according to Example 1. After 4 hours, 400 g of polymer with an intrinsic viscosity of 2.1 dl / g measured in tetralin at 135 ° C was obtained. The yield of the polymer was 300 080 g / g of Ti.

Example IV 9.25 g MgCl₂ ground according to example III 0.14 g TiCl₄ and 56 ml of n-heptane were treated as described in example 411. The solid product obtained by analysis contained 0.38% Ti. 8.0738 g of this product was used for the polymerization of ethylene under the conditions given in Examples 1 to 3. After 4 hours, 151 g was obtained; polymer with intrinsic viscosity 2.9 dl / g measured in tetralin at 135 ° C. The yield in polymer amounted to 596,000 g / g of Ti.

Example 10 g MgCifc was ground under the conditions given in Example III, then treated with 0.59 g TiCl according to the given example₄ and 75 ml n-heptane. The solid product obtained contained 0.38% Ti. 0.0746 g of this product was used for the polymerization of ethylene carried out according to the examples given above. After 4 hours, 182 g of polymer with an intrinsic viscosity of 2.4 dl / g was obtained, measured in tetralin at 135 ° C. The yield in polymer amounted to 277,006 g / g of Ti.

Example VI. The product obtained according to example V, from which the solvent was removed by evaporation, was washed with n-heptane to react negatively to the chloride ion in the washes. The Ti content of the washed product was 0.16%. 0.4829 g of the obtained product used for the polymerization of ethylene under the conditions given in the examples above. After 4 hours of polymerization, 279 g of polymer were obtained. The yield was 435,000 g / g TL

Example VII. 15.2 g of anhydrous MgCl_t with particle sizes of 125 — Ι77μ and a specific surface area of ​​1 m²/ g and 6.64 g TiCl₄, 75 ml of n-heptane was treated as described in example III. After evaporation of the solvent, the analysis showed a content of 0.25% TL 0.1053 g of product retained and was used for the ethylene polymerization reaction carried out under the conditions given above. After a polymerization of 4 hours, 17.6 g of polymer was obtained with a yield of 67 000 g / g of Ti.

Example VIII. The products obtained according to the above examples, from which the solvent was removed by evaporation, were washed several times with n-heptane to react negatively to chloride ions in the washes. The product washed in this way contained 0.09% Ti. 0.751 g of this product was used for the polymerization of ethylene, carried out according to the examples given above. After 4 hours of polymerization, 34 g of polymer were obtained with a yield of 50,000 g / g of Ti.

Example IX. 29 g anhydrous MgCl₂ with a specific surface area of ​​0.5 m²/ g was introduced into an autoclave, equipped with a stirrer and filter plate, containing 300 ml of TiCl₄, heated to 135 ° C. After heating for 1 hour, excess TiCl was removed₄ by filtration. The solid product in the autoclave was washed several times with cyclohexane until the TiCl was completely washed away₄. According to the analysis, the product thus obtained contained 0.18% Ti and 73.1% C31. 0.57 g of this product was used for ethylene polymerization according to the examples above. After 4 hours of polymerization, 401 g of polymer was obtained with an intrinsic viscosity in tetralin at 135 ° C of 2.8 dl / g. The yield in polymer amounted to 400,000 g / g of Ti.

Example X. The procedure of Example 9 was followed, except that MgCl was used₂ pre-ground for 2.5 hours in a ball mill described in the examples above. After treatment with TiCl₄ analysis of the washed product showed 0.68% Ti and 72.8% Cl. 0.170 g of this product was used for the polymerization of ethylene, carried out according to the examples given above. After 4 hours of polymerization, 446 g of polymer was obtained with a yield of 400,000 g / g of Ti.

Example XI. Example 9 was followed with the difference that 22 g MgCl was used₂ not activated, by milling and showing an average product size of 125-177 and a specific surface area of ​​1 m²/ G. After treatment with TiCl₄ the washed and dried product contained 0.3% Ti and 72.8% Cl. 0.31 g of this product was used for the polymerization of ethylene, carried out according to the examples given above. After 4 hours of polymerization, 271 g of polymer was obtained with a yield of 291,000 g / g of Ti. ?

Example XII. 35 g of magnesium chloride used in Example 11 were dispersed in 130 ml of TiCl₄. The suspension was stirred at room temperature for 24 hours, after which excess TiCl was removed₄ by draining. The solid product was washed several times with cyclohexane to remove TiCl completely₄ in industry. According to the analysis, the washed and dried product contained 0.066% Ti. 0.31 g of this product was used for polymerization carried out according to the examples given above. After 2 hours of polymerization, no polymer was formed.

Example XIII. 7.1 g MgBr₂ was ground in a ball mill according to example I, within 3 hours₇ gin in the presence of 0.5120 g TiCl₄. The Ti content of the milled product was 1.3%. The specific surface area of ​​the product reached 27 m²/ G. 0.051 g of this product was used for the polymerization of ethylene, carried out according to the examples given above. After 4 hours, 330 g of polymer with an intrinsic viscosity of 2.3 dl / g were obtained. The yield in polymer amounted to 500,000 g / g of Ti.

Example XIV. MgCl₂ used in this example was obtained by reaction C₂H₅MgCl in an ether solution with anhydrous HCl gas which was passed through a solution for MgCl precipitation₂which was then filtered off and dried at 200 ° C under reduced pressure. The specific surface of the product was 142 m²/ ga x-ray spectrum showed a clear expansion of the diffraction line at d = 2.56 A. 9.25 g of this product, 0.14 g TiBr₄ and 50 ml of n-heptane was introduced into a 250 ml vessel equipped with a stirrer, the suspension was stirred for 1 hour at room temperature and the solvent was evaporated. 0.073 g of used product^rfor the polymerization of ethylene according to the examples above. After 4 hours, 150 g of polyethylene with an intrinsic viscosity of 2.3 dl / g was obtained. ''

Example XV MgCl used in this example₂ obtained by rapidly evaporating a solution of 15 g MgCl₂ with a specific surface area of ​​1 m²/ g in 200 ml CH3OH and removal of residual alcohol by heating at 300 ° C under reduced pressure. The MgCl2 obtained had a specific surface area of ​​32 m²/ gi showed a significant expansion of the diffraction line that occurs in the normal spectrum of MgCl2 at d = 2.56 A. 9.25 g of this product, 0.14 g of TiCl₄ and 30 ml of n-heptane was introduced into a 250 ml flask equipped with a stirrer. The suspension was stirred for 1 hour at room temperature, then the solvent was evaporated. 0.05 g of this product was used for the polymerization of ethylene, carried out according to the examples given above. 150 g polyethylene with intrinsic viscosity of 2.1 dl / g was obtained.