Patent GB-609086-A (GB)
Title: Improvements in or relating to the vulcanization of natural or synthetic rubber
IPC: C08K5/00
Filed: 1946-03-05
Abstract: Synthetic rubbers, including copolymers of butadiene, isoprene, 2,3-dimethyl butadiene, and piperylene, with acrylonitrile, styrene, methyl acrylate, methyl methacrylate, and isobutylene are vulcanised in the presence of a mixed organo metallic salt consisting of a polyvalent metal joined to the N-methylene dithiocarbamic acid group and to a sulphide radical derived from a sulphhydryl compound by replacing the hydrogen atoms of the -SH group.  The salt is prepared by reacting equimolecular proportions of formaldehyde and aluminium dithiocarbamate in an aqueous medium, dissolving the white precipitate thus formed in an aqueous solution of an alkali metal hydroxide which solution is then treated with an acidified aqueous medium of a water-soluble salt of a metal having a valency greater than one, and an alkali metal salt of a sulphhydryl compound.  The preferred metals are zinc, lead, manganese, iron, and copper and the sulphhydryl compounds may be thio-acids such as dithionic, dithiocarbamic and xanthogenic acids and mercaptans such as 2-mercaptothiazole, 2-mercaptothiazoline, 2-mercaptothiazine, 2-mercapto-oxazole, 2-mercapto-oxazoline and mercaptoquinoline. Specified salts are zinc and manganous N-methylene dithiocarbamate dimethyl dithiocarbamate; zinc and lead N-methylene dithiocarbamate diethyl dithiocarbamate; zinc and manganous N-methylene dithiocarbamate benzothiazyl mercaptide; zinc and lead N-methylene dithiocarbamate 4,5-dimethyl thiazyl mercaptide; zinc N-methylene dithiocarbamate 4-ethyl thiazyl mercaptide; zinc and manganous N-methylene dithiocarbamate thiazolinyl mercaptide; zinc and manganous N-methylene dithiocarbamate 4-methyl 6-dimethyl thiazinyl mercaptide.  In examples, one or a mixture of these salts is used to accelerate the curing of a mixture containing a butadiene-styrene copolymer together with carbon black, zinc oxide, sulphur and an antioxidant.ALSO:Synthetic rubbers are vulcanized in the presence of a mixed organo metallic salt consisting of a polyvalent metal joined to the N-methylene dithiocarbamic acid group and to a sulphide radical derived from a sulphhydryl compound by replacing the hydrogen atoms of the -SH group.  The salt is prepared by reacting equimolecular proportions of formaldehyde and ammonium dithiocarbamate in an aqueous medium, dissolving the white precipitate thus formed in an aqueous solution of an alkali metal hydroxide, which solution is then treated with an acidified aqueous medium of a water-soluble salt of a metal having a valency greater than one, and an alkali metal salt of a sulphhydryl compound.  The preferred metals are zinc, lead, manganese, iron and copper, and the sulphhydryl compounds may be thio-acids such as dithionic, dithiocarbamic and xanthogenic acids and mercaptans such as 2 - mercaptothiazole, 2 - mercaptothiazoline, 2 - mercaptothiazine 2 - mercapto-oxazole, 2 - mercapto - oxazoline and mercaptoquinoline. Specified salts are zinc and manganous N-methylene dithiocarbamate dimethyl dithiocarbamate; zinc and lead N-methylene dithiocarbamate diethyl dithiocarbamate; zinc and manganous N - methylene dithiocarbamate benzothiazyl mercaptide; zinc and lead N-methylene dithiocarbamate 4,5-dimethyl thiazyl mercaptide; zinc N-methylene dithiocarbamate 4-ethyl-thiazyl mercaptide; zinc and manganous N-methylene dithiocarbamate thiazolinyl mercaptide; zinc and manganous N-methylene dithiocarbamate 4-methyl-6-dimethyl thiazinyl mercaptide.ALSO:Natural and synthetic rubbers are vulcanized in the presence of a mixed organo metallic salt consisting of a polyvalent metal joined to the N-methylene dithiocarbamic acid group and to a sulphide radical derived from a sulphhydryl compound by replacing the hydrogen atoms of the -SH group.  The salt may be made according to the method described in Group IV.  The preferred metals are zinc, lead, manganese, iron and lead, and the sulphhydryl compounds from which the salts are made may be thio-acids such as dithionic, dithiocarbamic and xanthogenic acids, and mercaptans such as 2-mercaptothiazole, 2-mercaptothiazoline, 2-mercaptothiazine, 2-mercapto-oxazole, 2-mercapto-oxazoline, and mercaptoquinoline. Specified salts are zinc and manganous N-methylene dithiocarbamate dimethyl dithiocarbamate; zinc and lead N-methylene diathiocarbamate; diethyl dithiocarbamate; zinc and manganous N-methylene dithiocarbamate benzothiazyl mercaptide; zinc and lead N-methylene dithiocarbamate 4, 5 dimethyl thiazyl mercaptide; zinc N-methylene dithiocarbamate 4 ethyl thiazyl mercaptide; zinc and manganous N-methylene dithiocarbamate thiazolinyl mercaptide; zinc and manganous N-methylene dithiocarbamate 4 methyl, 6 dimethyl, thiozinyl mercaptide.  The term natural rubber includes caoutchouc, balata, guttapercha, latex, and reclaimed natural rubber; and the synthetic rubbers are those vulcanizable with sulphur such as polymers of butadiene, isoprene, 2, 3 dimethyl butadiene, and piperylene and copolymers of these compounds with acrylonitrile, styrene, methyl acrylate, methyl methacrylate, and isobutylene.  In examples one, or a mixture of these salts is used to accelerate the curing of a mixture containing either natural rubber or a butadienestyrene copolymer together with carbon black, zinc oxide, sulphur and an anti-oxidant.