GB830791A - Sulphur-vulcanizable rubber compositions - Google Patents

Abstract

A hexathio-bis-secondary amine produced from a water-soluble secondary aliphatic or cycloaliphatic amine containing only carbon, hydrogen, and nitrogen, and further containing 2 to 12 inclusive carbon atoms per molecule of amine, is prepared from an initially produced amine di-, tri-, or tetra-sulphide by reaction with sulphur, or by reacting the amine with a sulphur chloride and sulphur in the presence of an alkali and in an aqueous medium. Specified amines for use as starting materials are dimethyl-, methylethyl-, diethyl-, di-n-propyl-, di-isopropyl-, dibutyl-, diamyl-, dihexyl-, dicyclopentyl-, and dicyclohexyl-amines. A slightly soluble amine is dissolved in water for the reaction, and the amount dissolved may be increased by adding a chemically inert watermiscible organic liquid, e.g. dioxane-1,4. Examples describe the preparation of hexathiobis-dimethylamine and hexathio-bis-diethylamine.ALSO:A sulphur-vulcanizable natural or synthetic rubber composition containing no free sulphur contains 0.1 to 2 parts by weight per 100 parts rubber of a hexathio-bis-secondary amine produced from a water-soluble secondary aliphatic or cycloaliphatic amine containing only carbon, hydrogen and nitrogen and further containing 2 to 12 carbon atoms per molecule. The hexathio-bis-secondary amine is prepared from an initially produced amine di-, tri-, or tetrasulphide by reaction with sulphur, or by reacting the amine with a sulphur chloride and sulphur in the presence of an alkali and in an aqueous medium. Specified amines for use as starting materials are dimethyl-, methylethyl-, diethyl-, di-n-propyl-, di-isopropyl-, dibutyl-, diamyl-, dihexyl-, dicyclopentyl-, and dicyclohexyl-amines. The vulcanizable composition may contain a known accelerator, e.g. cyclohexyl benzothiazyl sulphenamide, mercaptobenzothiazole, dithio - bis - benzothiazole, diphenyl guanidine, an aldehyde amine, a dithiocarbamate, a thiuram sulphide, or a xanthate. The specified synthetic rubbers are copolymers of butadiene and styrene or acrylontrile, or of isobutene and isoprene or butadiene, polybutadienes, and polyisoprenes. Reclaimed natural and/or synthetic rubber may also be used in the composition. The hexathio-bis-secondary amine may be incorporated in the composition by milling or by adding an aqueous dispersion thereof to a latex of natural and/or synthetic rubber. Alternatively it may be added directly or in a compatible solvent to a rubber solution to be used as a cement. Examples are specified of vulcanizable compositions including (a) natural rubber and hexa-thio-bis-dimethylamine, (b) butadiene-styrene copolymer and hexa-thio-bis-dimethylamine, and (c) butadiene-styrene copolymer and hexa-thio-bis-diethylamine, respectively.