GB793609A - Improved vulcanisation process for rubber - Google Patents

Abstract

In a process for vulcanizing synthetic rubber there is prepared a vulcanizable mix comprising the synthetic rubber, a reinforcing type furnace black, sulphur as essential vulcanizing agent, an accelerator, and an N,N1-dithio-bis-alkylaniline, e.g. N,N1-dithio-bis-methylaniline, N,N1 - dithio - bis - butylaniline, or N,N1-dithio-bis-ethylaniline, preferably in an amount of 0.5 per cent by weight of the synthetic rubber. The amount of sulphur is preferably between 2 and 3 per cent, and that of accelerator up to 1.5 per cent, by weight of the synthetic rubber, which may be selected from polymers of butadiene 1 : 3,2-methybutadiene-1,3, or isobutene, and copolymers of these compounds with acrylonitrile, styrene, methylmethacrylate, and other compounds copolymerizable therewith. The accelerator is preferably of the delayed action type, e.g. a thiazole sulphenamide such as N-tert.-butyl, N-tert.-octyl, or N-cyclohexyl benzthiazyl sulphenamide, or benzthiazyl sulphenmorpholide or sulphenpiperide, or a substituted mercaptobenzthiazole such as 2 : 4-dinitrophenyl-2-benzthiazyl monosulphide, ethylbenzthiazyl disulphide, or 2 : 21-dibenzthiazyl disulphide. The N,N1-dithio-bis-alkylaniline and the accelerator may be incorporated in the synthetic rubber mix as a previously blended mixture. In an example, N,N1-dithio-bis-ethylaniline is incorporated in a vulcanizable mix containing a butadiene-styrene copolymer. Specification 711,236 is referred to.ALSO:In a process for vulcanizing natural or synthetic rubber there is prepared a vulcanizable mix comprising the rubber, a reinforcing type furnace black, sulphur as essential vulcanizing agent, an accelerator, and an N; N1-dithio-bis-alkylaniline, e.g., N; N1-dithio-bis-methyl-aniline, N; N1-dithio-bis-butylaniline, or N; N1-dithio-bis-ethylaniline, preferably in an amount of 0,5 per cent by weight of the rubber. The amount of sulphur is preferably between 2 and 3 per cent and that of accelerator up to 1,5 per cent by weight of the rubber. As examples of synthetic rubbers are specified polymers of butadiene 1 : 3, 2-methylbutadiene-1,3, or isobutene, and copolymers of these compounds with acrylonitrile, styrene, methylmethacrylate, and other compounds copolymerizable therewith. The accelerator is preferably of the delayed action type, e.g., a thiazole sulphenamide such as N-tert. butyl, N-tert. octyl, or N-cyclohexyl benzthiazyl sulphenamide, or benzthiazyl sulphenmorpholide or sulphenpiperide, or a substituted mercaptobenzthiazole such as 2 : 4-dinitrophenyl-2-benzthiazylmonosulphide, ethylbenzthiazyl disulphide, or 2 : 21-dibenzthiazyl disulphide. The N; N1-dithio-bis-alkylaniline and the accelerator may be incorporated in the rubber mix as a previously blended mixture. In one of the examples a rubber stock comprising smoked sheet 100 (parts by weight), zinc oxide 5, furnace black 47,5, stearic acid 3, sulphur 2,5, N-cyclohexyl benzthiazyl sulphenamide 0,65, and N; N1-dithio-bis-ethylaniline 0,5, is vulcanized at 141 DEG C. for 25 minutes. Specification 711,236 is referred to.