GB340008A - Improvements in the polymerisation of diolefines - Google Patents

Abstract

The polymerization of diolefines by means of alkali or alkaline earth metals or their alloys is effected in presence of an organic compound containing a carbon atom with at least two valencies satisfied by oxygen. Suitable compounds are saturated and unsaturated acyclic or, preferably, cyclic acetals, or the components of such acetals, e.g. dibutyl acetal, ethylene acetal or other acetals from 1 : 2 and 1 : 3 glycols with aldehydes, unsaturated acetals such as those from crotonaldehyde or acrolein and butylene glycol. Or one may add ketones, which may be aliphatic, aromatic or hydroaromatic or may contain two different radicals from these classes, e.g. acetone, methyl ethyl ketone, cyclohexanone, quinone, acetophenone, benzophenone or furfural. Or aldehydes, especially unsaturated aldehydes, may be added, e.g. formaldehyde, acetaldehyde, crotonaldehyde, acrolein, benzaldehyde, or cinnamic aldehyde. Esters, especially ortho-esters, may be used, e.g. orthoformic or orthocarbonic ethyl ester, or amyl acetate, ethyl acetate, ethyl crotonate or phthalic diethyl ester. Acids e.g. acetic and formic acids may be employed, but preferably in very small amounts. The amount of these agents added is usually between 0,05 and 5 per cent by weight of the diolefine under treatment. If this organic agent reacts with the metal used, excess of the metal is usually taken, so that some free metal is available for the polymerization, but when the product of this reaction with the metal is itself a polymerizing agent, an excess of the metal is unnecessary. Using small quantities of the said organic compounds, tough products are obtained, and with greater additions, soft and plastic materials are obtained. The process may be carried out with the further addition of solvents or in the presence of the cyclic diethers or unsaturated ethers described in Specifications 334,184 [Class 2 (iii), Dyes &c.], and 340,474. The said organic compounds are usually employed in a finely dispersed state i.e. they should be soluble in the reaction mixture, or they are employed in the liquid or gaseous state, or as solutions, true or colloidal, or as emulsions or as a finely divided suspension. A wide range of temperature may be used, and the range from room temperature to 90 DEG C. is mentioned in particular. Examples are given of the use of a dibutyl acetal, ethylene acetal, the acetal from crotonaldehyde and 1 : 3 butylene glycol, the acetal from acrolein and 1 : 3 butylene glycol, acetophenone, benzophenone, crotonaldehyde, stearic acid and vinyl ethyl ether, phthalic diethyl ester, ethyl orthoformic ester, and oleic acid. The products may be used in the preparation of vulcanization products similar to rubber products or for the manufacture of coatings, films, lacquers, artificial silk and the like. Specification 320,362, [Class 2 (iii), Dyes &c.], also is referred to.