SU975725A1 - Process for producing copolymers of ethylene with alpha-olefins - Google Patents

Description

The invention relates to the technology of producing modified polyethylene, in particular to the preparation of a copolymer of ethylene with alpha-olefins, and can be used in the chemical industry.

It is known that high pressure polyethylene (HDPE) has a density. 0.92-0.93 g / cm and a crystallinity of 53-67% and is perfectly processed into any products. However, the complexity of its production technology, the need to use apparatus designed for high pressure (10003000 atm) requires the search for other methods of obtaining polyethylene of this density.

A known method for producing copolymers of ethylene with alpha-olefins contained in the benzoic distillate of high-speed cracking of paraffins and oil.

The copolymerization process is carried out on an oxide-chromium catalyst at 60-130 ° C and 30-40 atm 1}.

The disadvantages include the instability of the composition of the distillate containing olefins and paraffins Cr-C, as well as the high crystallinity of the obtained product - 75-80%.

The minimum density of the obtained copolymer is 0.92-0.95 g / cm.

The closest to the invention according to the technical nature is a method for producing a copolymer of ethylene with gisha-olefingyl or polymerization of ethylene in a hydrocarbon solvent at 90-110 ° C and 38-42 atm in the presence of a bifunctional chromo-nickel magnesium aluminosilicate catalyst. The catalyst used has a bifunctional action — ethylene dimers to butene-1 and copolymerizes them. The resulting ethylene-butene-1 copolymer has improved physicomechanical properties (increased elongation, cracking resistance) 2J.

20

The disadvantage of this method is the relatively high crystallinity () and density (0.92 or more) of the copolymer obtained.

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The aim of the invention is to reduce the density and crystallinity of the copolymers.

This goal is achieved by the fact that according to the method for producing copolymers

30 ethylene with alpha-olefins polymerization of ethylene in the medium of a carbohydrate solvent at 90–110 ° C and 38–42 atm in the presence of a bifunctional chromium nickel – magnesium alkoxylate. The process is carried out in the presence of 0.12-0.36 mol / octene-1 solvent as a monomer. The resulting ternary copolymer of ethylene, butene-1 and octene-1, has a crystallinity of 50-62% and a density of Z0, 88-0.92 g / cm. Example. The preparation of the ethylene-butene-1-octene-1 terpolymer is carried out on a chromo-nickel magnesium aluminosilicate kg talienator having the following composition, wt.%: Crj ,, 76; N10 6.54; 6.9; MDO 6.9; SlO 77.9. Porous structural characteristics of catalysts, Loose weight, g / cm 0.43 True specific secj g / cm2,41 Apparent specific weight, g / cm C, 74 Porosity,% 69 Specific pore volume,, 75 Specific surface, ° Average pore radius, A 42 After vacuum activation (10-2. 1CGBMHM), 0.6 g of the catalyst in a glass ampoule is placed in a 2.5 p autoclave. The autoclave is sealed and purged. ethylene or gas (MD) at 180200 ° C for 2-3 hours and then cooled to room temperature. After that, 500 ml of hexane 11 are fed, which is purified over silica gel and purged of dissolved air with monomeric ethylene. containing 21 ml of octene-1 (0.3.8 molDg). The autoclave is heated to 90 ° C and ethylene is fed, the pressure is adjusted to 40 atm, and the electric mixer is broken, the ampoule with the catalyst being broken. The pressure drop in the autoclave indicates the reaction. Feeding ethylene in the autoclave every 2-3 minutes, maintain pressure at the initial 5f. After one hour, the ethylene feed is stopped and the autoclave is cooled. Before opening the autoclave, a gas sample is taken for analysis, and after it is opened, the liquid phase is taken. The polymer is discharged, separated from the solvent, dried under vacuum in a drying oven, and its properties are examined. Example 2. The catalyst and copolymer synthesis conditions are the same as in Example 1, but octene-1 is introduced in an amount of 40 ml (0.36 mol / l). Froze The catalyst and copolymer synthesis conditions are the same as in Example 1, but the process is carried out at 38 atm. Example 4 The catalyst and polymer synthesis conditions are similar to Example -1, but the amount of octene-1 is 13 ml (0.12 mol / l) and the process is carried out at 42 atm. PRI me R 5 (comparative). Ethylene is polymerized under conditions analogous to example 1, but without the supply, octene-1. The results for examples 1-5 are listed in the table. As can be seen from the table, the copolymers obtained, as compared with the known ones, have a lower density and crystallinity and are excellent materials for the production of films, sheets, pipes, hoses, machine parts and other products, as well as resin modifiers.

0.36

40 40 36 42 40

90 0.16

90 0.18

110 0.12

100

90

Claims (2)

1. Authors certificate of the USSR I 175658, cl. C 08 F 210/02, 1965. 2. Authors certificate of the USSR About 228273, cl. C 08 F 210/02, 1968 (prototype).