Patent GB-488910-A (GB)
Title: Improvements in vulcanisation of rubber
IPC: C08K5/00
Filed: 1937-11-09
Abstract: The vulcanization of rubber is accelerated by the addition to the mix of the reaction product of an aldehyde and an ammonium or a substituted ammonium salt of a carboxylic acid.  The products are either low melting resins or viscous oils and are of indefinite composition.  Either aromatic or aliphatic aldehydes may be used but the latter are preferred.  Aldehydes mentioned include formaldehyde, acetaldehyde, valeraldehyde, crotonaldehyde aldol, benzaldehyde, cinnamic aldehyde, furfuraldehyde and furyl acrolein.  A number of carboxylic acids are mentioned of which acetic, glycollic, lauric, oleic, maleic, benzoic and furoic acids are typical.  There may also be used the (carboxymethyl) p  dithiocarbamates of the formula <FORM:0488910/IV/1> , where X is a methylene radical and M is a primary or secondary amino group.  A number of compounds of this class are mentioned of which the following are typical, (carboxymethyl) - N - ethyl-cyclohexyldithiocarbamate, and (carboxymethyl) phenyl dithiocarbamate.  The corresponding xanthates in which M in the formula above is alkoxy and compounds in which M is a heterocyclic or aromatic radical may also be used, examples being (carboxymethyl) isopropyl xanthate, and (carboxymethyl) dithiofuroate.  Another class of useful carboxylic acids comprises compounds of the formula R-X-COOH where X is methylene and R is aryloxy or a 2-mercaptothiazole residue.  The amines used to form the ammonium salts of the above acids may be aliphatic, aromatic or heterocyclic amines, of which aliphatic amines are preferred.  These may be straight or branched chain, cyclic, and saturated or unsaturated.  Numerous examples of the different classes of amines are given.  The reaction of the ammonium carboxylate with the aldehyde is usually carried out at a temperature of 100 DEG  C. or higher, and for one to 12 hours.  The molecular ratio of aldehyde to salt is usually about 1,5 to 1. In some cases, however, the proportion is raised to 6 to 1.  In examples the following salts and aldehydes are reacted together (1) the cyclohexylamine salt of carboxy methyl benzothiazyl sulphide and heptaldehyde; (2) cyclohexyl ammonium phthalate and crotonaldehyde; (3) cyclohexyl ammonium stearate and heptaldehyde in the ratio of 1-1,5 mols.; (4) as in (3) using a ratio of 1-6 mols.; (5) tetrahydro alpha furfuryl ammonium stearate and heptaldehyde; (6) the piperidine salt of (carboxymethyl) pentamethylene dithiocarbamate and crotonaldehyde; (7) the cyclohexylamine salt of carboxy-methyl-dimethyldithiocarbamate and formaldehyde; (8) the p-p1-diaminodiphenylmethane salt of (carboxymethyl) dimethyldithiocarbamate and butyraldehyde; (9) the polyethylene polyamine salts of stearic acid and butyraldehyde; (10) the cyclohexylamine salt of 2-(carboxymethylmercapto) benzothiazole and crotonaldehyde; (11) as (10) using double the amount of crotonaldehyde; (12) the tetrahydro alpha furfurylamine salt of (carboxymethyl) dicyclohexyldithiocarbamate and crotonaldehyde; (13) the tetrahydro alpha naphthylamine salt of carboxymethyl ditetrahydro alpha furfuryldithiocarbamate and crotonaldehyde; (14) the crotonal - cyclohexylamine salt of (carboxymethyl) dimethyldithiocarbamate and crotonaldehyde; (15) cyclohexylamine stearate and crotonaldehyde; (16) ethylene di(ammonium benzoate) and crotonaldehyde; (17) the ethylene diamine salt of (carboxymethyl) dimethyldithiocarbamate and crotonaldehyde; (18) the cyclohexylamine salt of (carboxymethyl) dimethyldithiocarbamate and benzaldehyde; (19) the oleic acid salt of ethylene diamine and heptaldehyde; (20) the oleic acid salt of p-p1-diaminodiphenylmethane and heptaldehyde; (21) the oleic acid salt of methylamine and heptaldehyde; (22) the cyclohexylamine salt of (carboxymethyl) butyl xanthate and heptaldehyde; (23) as in (22) using crotonaldehyde; (24) the cyclohexylamine salt of (carboxymethyl) dicyclohexyldithiocarbamate; (25) the tetrahydro-alpha-furfurylamine salt of (carboxymethyl) dimethyl dithiocarbamate; (26) the cyclohexylamine salt of (carboxymethyl) dimethyldithiocarbamate and heptaldehyde; (27) ethylene di(ammonium benzoate) and heptaldehyde; (28) cyclohexylammonium oleate and heptaldehyde; (29 the ethylene diamine salt of (carboxymethyl) pentamethylene dithiocarbamate and heptaldehyde; (30) amyl ammonium oleate and heptaldehyde; (31) butylammonium oleate and heptaldehyde; (32) the stearic acid salt of polyethylene polyamines and heptaldehyde; (33) the cyclohexylamine salt of (carboxymethyl) dimethyldithiocarbamate and crotonaldehyde; (34) the cyclohexylamine salt of (carboxymethyl) dimethyldithiocarbamate and butyraldehyde; (35) the cyclohexylamine salt of a -a 1-dicarboxy-tetramethylene benzothiazyl sulphide and crotonaldehyde.  Examples are given to show the efficiency of the accelerators of the invention when incorporated in a standard rubber mix.ALSO:The vulcanization of rubber is accelerated by the addition to the mix of the reaction product of an aldehyde and an ammonium or a substituted ammonium salt of a carboxylic acid.  The products are either low melting resins or viscous oils, and are of indefinite composition.  Either aliphatic or aromatic aldehydes may be used, but the latter are preferred. Aldehydes mentioned include acetaldehyde, formaldehyde, valeraldehyde, crotonaldehyde, aldol, benzaldehyde, cinnamic aldehyde, furfuraldehyde and furyl acrolein.  A number of carboxylic acids are mentioned of which acetic, glycollic, lauric, oleic, maleic, benzoic, and furoic acids are typical.  These may be also used the (carboxymethyl)dithiocarbamates of the formula <FORM:0488910/V/1> , where X is a methylene radical, and M is a primary or a secondary amino group, a number of compounds of this class are mentioned of which the following are typical, (carboxymethyl)-N-ethyl-cyclohexyldithio - carbamate, and carboxymethyl phenyl dithiocarbamate.  The corresponding xanthates in which M in the formula above is alkoxy, and compounds in which M is a heterocyclic or an aromatic radical may also be used, examples being (carboxymethyl) isopropyl xanthate, and (carboxymethyl) dithiofuroate.  Another class of useful carboxylic acids comprises compounds of the formula R-X-COOH, where X is methylene and R is aryloxy or a mercaptothiazole residue.  The amines used to form the ammonium salts of the above acids may be aliphatic, aromatic, or heterocyclic amines, of which aliphatic amines are preferred.  These may be straight or branched chain, cyclic, and saturated or unsaturated.  Numerous examples of the different classes of amines are given.  The reaction of the ammonium carboxylate with the aldehyde is usually carried out at a temperature of 100 DEG  C. or higher, and for one to 12 hours.  The molecular ratio of aldehyde to salt is usually about 1,5-1.  In some cases however the proportion is raised to 6-1.  Numerous examples of the preparation of the compounds for use according to the present invention are given, together with tables showing the efficiency of the compounds when incorporated in a standard rubber mix.