SU504795A1 - The method of obtaining chlorine-containing polymers - Google Patents

Description

one

This invention relates to the field of polymer synthesis.

The main method for producing polymers of chlorine-containing unsaturated compounds, in particular chloroprene and vinyl chloride, is free radical polymerization of monomers in bulk, suspension and aqueous emulsion. Radical polychloroprene crystallizes easily, which makes it difficult to process. In addition, in the case of radical polymerization, special emulsifiers must be used, which mainly fall into sewage, sulfur, thiuram and other substances are used to regulate the molecular weight of polychloroprep, which is part of rubber, which impairs its properties. Radical polymerization methods do not allow the regulation of the microstructure of the chain, and hence the fundamental properties of polymers.

Anionic polymerization of these monomers under the influence of organometallic compounds opens up the possibility of regulating the microstructure of the chain and obtaining new types of copolymers due to the change in the copolymerization constants (L and rz during the transition from the radical chain growth mechanism to the anionic one. However, organometallic compounds of metals usually used for anion polymerization Groups I-II of the periodic system are not very suitable for chlorine-containing monomers due to the destruction of the catalyst due to the reaction of Würz with the participation of Thieme these monomers and the formed polymers iznih (RCl + RMe- R-R-f MeCl), which leads to the cessation of the polymerization process at a low conversion (5-20%).

Polymers of dienes under the influence of organometallic compounds of titanium and zirconium deposited on hydroxyl-containing solid carriers 1 are described. In the patent, without citing experimental data, the possibility of chloroprene polymerization on the same heterogeneous systems is noted.

The possibility of polymerization of vinyl chloride on organometallic compounds deposited on solid substrates of some transition metals (Ti, Zr, Hf, Cr) is also mentioned, however, no experimental data are given 2.

A method of producing chlorine-containing polymers is known by polymerizing chloroprene or copolymerizing it with other monomers in a hydrocarbon solvent at a temperature of O-80 ° C in the presence of allylchrome 3 as a catalyst.

However, the speed of the process, as follows from the data presented in the work, is extremely low: at chloroprene concentrations of 5 mol / l and (-C3H3) csg mol / l for 5 hours, the polymer yield is 7%. The insignificant efficiency of this catalyst may be associated with its destruction due to its low stability. The polymerization is carried out in a benzene solution at a temperature of from -10 to 50 ° C. (The polymerization of vinyl chloride on these catalysts could not be implemented).

In order to increase the yield of polymers, it is proposed to use as a catalyst organometallic compounds of metals of groups IV-VIII of the periodic system containing a-or-carbon-metal bonds, for example tetrabenzyl titanium, tribenzyl titanium iodide, -entyl metal complexes of the IV-VIII groups of the periodic system.

Organometallic compounds with 0-link

the transition metal-carbon contains bepzyl, neopentyl, trimethylsilylmethyl, and methyl methane naphthyl groups as hydrocarbon radicals. These compounds are characterized by considerable thermal stability: they are stable at ordinary temperatures. An example is tetrabenzyl titanium, tribenzyl titanium iodide, tetracyclohexyl titanium, tetrakis (trimethylsilylmethyl) titanium.

The used allyl transition metal complexes have increased stability due to the presence of alkyl groups on the first and third carbon atoms of the allyl ligand:

MeHg

t

where t is 1, 2, 3, 4;

, 2, 3;

X is a monovalent anion;

R% R2 is alkyl groups.

In the case of the pentenyl complex R

: ..

In the case of a cyclohexenyl complex, R and R2 are part of a six-membered cycle.

The polymerization process is carried out in a solution of aropic, aliphatic and chlorinated hydrocarbons at O-80 ° C in an atmosphere of an inert gas, such as argon.

The glass transition temperature of the synthesized polychloroprene is -50 ° C; the polymer does not crystallize.

Examples 1-23. An organometallic catalyst in the form of its hydrocarbon solution and the required amount of solvent are loaded into the reaction ampoule in an inert gas atmosphere. The solution is degassed, the previously purified and dried monomer is condensed in a vial in a vacuum, after which the vial is sealed off and thermostatic. At the end of the exposure at a given temperature, the vial is opened, the polymer is precipitated with methanol and dried.

The concentrations of monomer and catalyst, the type of solvent, as well as the conditions of polymerization and the yield of the polymer obtained are summarized in table. 1 and 2.

Table 1

) The composition of the copolymer in mol. %: chloroprene 14, butadiene 86.

Claims (1)

Table 2 7 Formulation -10 la, characterized in that, in order to increase the yield of polymers, organometallic compounds of metals of groups IV-VIII of the periodic system are used as catalysts, containing a-or-carbon carbon metal, for example, tetrabidyl titanium, tribenzyl titanium iodide, and rational metal complexes of groups IV-VIII of the periodic system. 1 Patent of Great Britain No. 1331319, cl. SZR, 1973. 2 Patent of Great Britain No. 1314828, cl. SZR, 1973 3 I. Chem. Soc., No. 10, 1168 (1968).