Patent GB-841392-A (GB)
Title: Process for the production of synthetic elastomeric shaped articles
IPC: C08J5/02
Filed: 1957-11-27
Abstract: Elastameric shaped articles are produced by passing an aqueous emulsion of a synthetic elastomeric polymer containing carboxyl groups into a coagulating bath containing a polybasic organic acid and, as a crosslinking agent, a polyamine, an amine alcohol, or a salt thereof with a monobasic organic acid or an inorganic acid. Suitable synthetic elastomers are butadienecarboxylic acid polymers and copolymers of butadiene, its homologues or derivatives, e.g. isoprene,2,3-dimethylbutadiene and 2-chlorobutadiene, with compounds containing free carboxyl groups, e.g. acrylic, methacrylic, sorbic, maleic and fumaric acids and maleic ester acids, or with compounds from which carboxyl groups can subsequently be abstracted.  The monomers may be polymerised in aqueous emulsion in the presence of emulsifiers with the aid of known radical-forming substances, e.g. potassium persulphate, to give polymers preferably containing about 0,2 to 20 mg. of carboxyl groups per 100 grams.  The emulsions preferably contain 10-60% by weight of the polymers, and stabilizers such as phenyl-b -naphthyl amine, condensation products of cresols and camphene, 2,6-ditert. butyl-p-cresol, aralkylated products of diphenylamines and 2,21methylene-bis-(4-methyl-6 cyclohexyl phenol) may be added in quantities of 0,5-5%, calculated on the weight of the polymers contained in the latices.  The emulsions may also contain sulphur and vulcanization accelerators natural or synthetic rubber latices, plasticisers, dyestuffs, pigments, solvents or other high molecular weight polymers capable of being cross-linked, e.g. polyacrylic acid, carboxy methyl cellulose, alginic acid, proteins such as casein, and polyesters.  Specified polyamines and amine alcohols used for cross linking are ethylene diamine, butylene diamine, hexamethylene diamine, diethylene triamine, dipropylene triamine, triethylene tetramine, tripropylene tetramine, pentamethylene hexamine, hydrazine, mono-, di-and tri-ethanolamines and ethanolmonomethylamine.  Examples of suitable polybasic organic acids are maleic, fumaric, itaconic, oxalic, succinic, glutaric, adipic, tartaric, citric, malonic, sebacic, phthalic, terephthalic, tri-, tetra-penta-, and hexbenzene, cyclohexanetricarboxylic, pyridine-a -b -dicarboxylic, diphenic, p,p1-diphenyl dicarboxylic, naphthalene polycarboxylic, triphenyl methane polycarboxylic, ethylenediaminotetraacetic and aminotriacetic acids, polysulphonic acids of benzene and of polynuclear hydrocarbons and polybasic acids containing carboxyl and sulphonic acid groups such as benzoic-sulphonic acids and naphthoic-sulphonic acids. The coagulation baths preferably contain sufficient cross-linking agent to react with at least 1/10 of the carboxyl groups, those containing 1-50% by weight of cross-linking agent and 1-50% by weight of polybasic organic acid in solution in water and/or alcohols, such as methanol and ethanol, being particularly suitable.  The coagulation baths preferably have pH values of about 5-12 and temperatures of about 20-70 DEG C. and may contain 1-30% by weight of coagulating agents, e.g. salts of monovalent metals such as sodium and potassium chlorides and sodium sulphate, and about 1-15% by weight of thickening agents, e.g. polyvinyl alcohol, salts of polyacrylic acid, alginic acid, carboxymethyl cellulose, casein, gelatine and agar-agar.  After leaving the coagulation bath the articles may be washed with water or alcohol at 20-70 DEG C. and dried at 50-150 DEG C.  The emulsions may be extruded through nozzles to produce threads and films or through annular nozzles to produce hoses, or they may be applied as a thin layer on to a firm surface, e.g. a mould, metal plate or rotating roller, and continuously coagulated or cross-linked Specification 785,631 is referred to.