FI87360C - Process for preparing ethylene-propylene copolymers in particulate form - Google Patents

Description

1 8 7 3 6 C

The invention relates to a process for the preparation of an elastomeric particulate ethylene-propylene copolymer or ethylene-propylene-diene terpolymer having an ethylene unit content of more than 35% by weight.

10 Ethylene-propylene elastomers, or EPR rubbers, can be divided into two groups: saturated ethylene-propylene copolymers (EPM) and ethylene-propylene-diene terpolymers (EPDM). These are mainly amorphous co- or terpolymers, the statistical structure of the repeat units of which affects the hardness of the polymer and its behavior under various weather conditions, such as its resistance to oxygen and ozone.

A Ziegler-Natta catalyst system consisting of 20 ns is commonly used to copolymerize these olefin elastomers. procatalyst and cocatalyst. The procatalyst is based on a transition metal compound belonging to groups IVB-VIII of the Periodic Table of the Elements and the cocatalyst is based on an organometallic compound of a metal belonging to groups IA-IIIA of the Periodic Table of the Elements. The catalyst system may also include a support on which the transition metal compound is deposited and electron-donor compounds that enhance and modify the catalytic properties.

U.S. Patent No. 4,013,823 describes the preparation of an elastomeric ethylene-propylene copolymer using a catalyst mixture comprising an Al halide and a Ti halide, wherein the Ti compound is deposited on an anhydrous Mg halide support and which is then complexed with an electrolytic Mg halide support. With 35 ronidonors.

GB patent publication 1 492 864 (= FI patent 59255) describes the preparation of a thermoplastic ethylene-propylene copolymer having elastic properties in the non-vulcanized state, even in the non-vulcanized state, by copolymerizing propylene and ethylene in an amount of 10 to 50% by weight using as a catalyst system, a mixture optionally containing Al-alkyl 5 complexed with a donor and a Ti halide complexed with a donor and supported on an activated anhydrous Mg halide support.

U.S. Pat. No. 4,331,561 (= FI patent 62672) describes catalysts suitable for the homo- or copolymerization of α-olefins, consisting of a donor-clad Al alkyl and a reactant of a donor-complexed Mg halide and a tetravalent Ti halide. . The resulting copolymer contains 40-60% by weight of propylene and has both polyethylene and polypropylene crystallinity.

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EP-60 090 discloses an ethylene-propylene copolymer prepared by polymerizing monomers at a temperature of 22-27 ° C (by way of example) with a catalyst mixture obtained by reacting one or more Al-trialkyls and / or Al -alkyl monohalide and Ti-halide on MgCl 2 or MgBr 2. The product obtained contains 40 to 60% by weight of propylene units, no polypropylene crystallinity and less than 10% polyethylene crystallinity.

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In processes for the preparation of elastomeric ethylene-propylene copolymers of the above type, the problem is that when a particulate product is formed, the particles adhere to each other and the polymer also precipitates on the inner walls of the reactor and other equipment in contact with the reaction mixture. In this case, it is often necessary to carry out the cleaning of the reactor equipment, which is an expensive and time-consuming operation.

It is an object of the present invention to provide a process for preparing an elastomeric particulate ethylene-propylene copolymer in which the particulate copolymer particles formed in the polymerization do not adhere.

3 H 7360 to each other and also to the walls of the polymerization reactor or to other surfaces of the apparatus in contact with the reaction mixture. This is now achieved by a new method, which is mainly characterized by what is said in the characterizing part of claim 1. It is thus realized that adhesion of the polymer to the surfaces of the reaction apparatus can be avoided by carrying out the polymerization in liquid propylene and at a temperature below 15 ° C. The adhesion is further reduced by the high ethylene unit content of the copolymer, which is preferably more than 35% by weight and most preferably 50% by weight. The procatalyst is a tetravalent Ti halide deposited on an Mg halide support and the cocatalyst is an Al-trialkyl organoaluminum compound. Special homogeneous catalyst systems can also be used. The ratio of procatalyst 15 to cocatalyst is about 20-200 and preferably about 100.

The most preferred monomer combination consists of propylene and ethylene. However, in addition to these monomers, diene can also be used as the third monomer. Typical dienes are dicyclopentadiene, ethylidene norbornene and hexa-1,4-diene.

The copolymerization is thus carried out by means of a Ziegler-Natta catalyst composition consisting of a so-called procatalyst and cook-25 lytes. The procatalyst is based on a transition metal compound belonging to groups IVB-VIII of the Periodic Table of the Elements and the cocatalyst is based on an organometallic compound of a metal belonging to groups IA-IIIA of the Periodic Table of the Elements. Catalyst systems generally also include a support on which a transition metal is deposited, as well as electron donor compounds that enhance and modify the catalytic properties of the system.

The polymerization is carried out as a precipitation polymerization in which the polymer is insoluble in the medium. Propylene in solution form can preferably be used as the medium. The reactor is an autoclave equipped with a stirrer, which is purged with nitrogen gas prior to polymerization to substantially reduce the oxygen content. Hydrogen can be advantageously used to adjust the chain length of the resulting copolymer.

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The copolymer of ethylene and propylene elastomer is obtained in particulate form when the number of ethylene-derived units of the copolymer exceeds 35% by weight (see Figure 1). The tack of the product decreases as the crystalline polyethylene sequences increase and the number of atactic polypropylene sequences decreases, but only when the polymerization temperature is kept low, i.e. below 15 ° C, do the particles adhere to different parts of the reactor.

The ethylene-propylene copolymer in particulate form is easy to handle, so it can be used for a variety of purposes where this property is an advantage. The copolymer can be vulcanized, especially if it contains a diene compound as a ter monomer component, in known ways with elemental sulfur, various sulfur compounds, peroxide compounds, azo compounds, irradiation, etc. From the savings in manufacturing inves-25 operating and operating costs.

The invention is illustrated in the following by examples in which the products obtained were analyzed by the methods mentioned below.

The crystallinity and glass transition temperature of the product were determined by DSC. Intrinsic viscosity was determined with a capillary viscometer at 135 ° C in decalin. The ethylene content of the product was determined using IR spectroscopy. · Absorptions at 1,150 cm-1 and 720 cm-1. Concentration correlation was calibrated by 13 C NMR analysis. The density of the product was determined in an ethanol-water mixture on a density gradient column.

5,87360

Example 1 An EPM elastomer was prepared in a 2 lsn autoclave equipped with a liquid propylene with a stirrer with two small windows on the side for the detection of 5 particulate particles formed during polymerization.

Before starting the polymerization, the reactor was evacuated and purged with nitrogen four times. Then, 26 mmol of hydrogen was added as a chain transfer agent, after which 500 g of liquid propylene was introduced into the reactor 10.

The polymerization was started by adding a catalyst system consisting of TiCl 4 on Mg chloride support and triethyl-Al (10% by weight heptane solution) in a molar ratio of 100. The catalyst components were stirred before being fed to the reactor. After the addition of hydrogen, propylene and catalyst, the pressure was raised to 8.0 bar by introducing gaseous ethylene into the reactor (ethylene overpressure was 0.5 bar). The pressure was maintained constant by the continuous addition of 20 ethylene, and the reaction mixture was stirred continuously at 600 rpm. The temperature was 0 ° C. The polymerization was stopped after 30 min by letting the unreacted monomer out of the reactor.

The activity of the catalyst was 14 kg copolymer / g * h. According to IR analysis, the copolymer contained 37% by weight of ethylene. According to DSC analysis, the copolymer had no polyethylene-type crystallinity, an intrinsic viscosity in decalin at 135 ° C of 2.53, a Shore A hardness of 49TM according to ASTM D 2240-81, and a density on a gradient column of 0.861 g / cm 2.

The product was in particulate form and the particles did not adhere to each other after removal of the monomers.

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Examples 2-15

The procedure set forth in Example 1 was repeated, but in these es i moi ke l:! Gesture In partial pressure Ja po I yme i <) I n t I I ämöl I 1 nn varied. The temperature was 1, 14 and 25 ° C and the total pressure was 8.0 and 18 bar. The polymerization conditions are shown in Table 1 and the properties of the products obtained are shown in Table 2. The dependence of the particle form on the polymerization temperature and ethylene content is shown in Figure 1.

Examples 16 and 17 In these examples, the procedure was as in Example 1, but with ethylene and propylene copolymers at -5 ° C and -10 ° C. The results are shown in Table 3.

15 Example 18

The procedure was as in Example 1, but the temperature was 14 ° C and the total pressure was 12.6 bar. Diphenyldimethylsilane was used as the external donor in the polymerization and the TEA / donor molar ratio was 10. The product was in particulate form and had properties 20 as shown in Table 3.

It can be seen from Figure 1 that when the ethylene content of the product ranged from 37 to 64% by weight (respectively, its polyethylene-type crystallinity ranged from 0 to 13% and the glass transition point ranged from 27 to -30 ° C, see Tables 1 and 2) and the product was polymerized. below 14 ° C, the product obtained was in the form of particulate particles which were not sticky and did not tend to adhere to each other or to the reactor parts.

30 Example 19

The procedure was as in Example 1, but the temperature was 14 ° C and the total pressure was 12.6 bar. The polymerization used the same type of catalyst as before, except that it also had an internal donor. The external donor was diphenyldimethyl-35 lisilane with a TEA / donor molar ratio of 10. Otherwise, all the same as in Example 1. The product is still in particulate form.

Analysis Results:

Density: 0.879 g / cm-1 40 Hardness: 70 Shore A units Ethylene content: 57% by weight

Intrinsic viscosity: 8.3 dl / g Crystallinity: 19%

Activity: 1.8 kg / (g catalyst * h).

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Example 20

Terpolymerization of ethylene, propylene and 5-ethylidene-2-norbornene was carried out as in Example 1, but with a total pressure of 12.6 bar and a polymerization temperature of 15 ° C. The medium was 450 g of propylene to which 22 g of 5-ethylidene-2-norborene had been added. Particulate EPDM elastomer was obtained with an activity of 3.5 kg / g cat * h.

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table 1

Esim._T / ° C_Pkok / bar_Pvl. p / bar 1 0 8.0 0.5 2 0 8.6 1.1 3 0 9.5 2.0 4 0 10.1 2.5 5 0 10.5 3.0 6 14 10.8 0 , 6 7 14 11.4 2.2 8 14 12.0 - 2.8 9 14 13.2 4.0 10 14 13.9 4.7 11 14 15.3 6.1 12 25 15.2 2, 1 13 25 16.5 4.4 14 25 17.4 5.2 15 25 18.0 5.9

Table 2

Eg Ethylene- Density Hardness [η] Crystalline- Catalyst-pit. g / cm3 Shore A dl / g September% activity _weight _kq / q cat. * h 1 37 0.861 49 2.53 - 14 2 49 0.862 47 2.47 6 20 3 55 0.868 56 2.74 11 22 4 55 0.870 54 2.95 12 20 5 62 0.872 58 '3.08 14 21 6 26 0.861 49 1.53 3 13 7 39 0.859 49 2.09 1 25 8 45 0.861 48 2.28 2 30 9 49 0.865 48 2.59 3 28 10 55 0.868 49 2.73 6 43 11 64 0.874 59 3.00 13 49 12 36 0.861 49 1.79 1 30 13 49 0.863 47 2.23 3 41 14 55 0.867 57 2.39 5 45 15 54 0.867 54 2.46 1 50

Table 3

Eg T Ethylene [η] Density Hardness Cat. Crystalline ° C pit. dl / g g / cm3 Shore A kg / g Sep _Weight -% _ cat. * h_% 16 -5 43 3.99 0.879 53 7.2 15 17 -10 39 3.70 0.868 44 6.6 11 18 14 51 4.10 0.865 52 11.2 8

Claims (1)

Process for the preparation of an elastomeric particulate ethylene-propylene copolymer or ethylene-propylene-diene terpolymer having an ethylene unit content of more than 35% by weight, characterized in that the polymerization of the monomers is carried out at a temperature below 15 ° C in liquid propylene. in the presence of a Ziegler-Natta catalyst composition consisting of a tetravalent Ti halide procatalyst and an Al-trialkyl-10 liococatalyst deposited on an Mg halide support. For the preparation of an elastomeric particle of an ethylene-propene copolymer or an ethylene-propene-diene terpolymer, 15 times the yield is 35% by weight, the conversion of polymerization to a monomer at a temperature of less than 15 ° C at a temperature of less than 15 ° C en Zieg-ler-Natta-katalysatorkomposition bestäende av en fyravärd tiLanhalogenid-procokysator avlagrad pä en magnesiumhalo-20 genidbärare samt en aluminiumtrialky1-kokatalysator.