Patent GB-763283-A (GB)
Title: Preservation of natural and synthetic rubbers, rubber articles, and rubber latices
Inventor: DAVY GEOFFREY SPENCER
IPC: C08K5/13
Filed: 1954-06-04
Abstract: Synthetic rubber articles and latices are preserved by incorporating therein an antioxidant of the formula <FORM:0763283/IV(a)/1> in which R1 is an alkyl radical and R2 is a tertiary hydrocarbon radical attached to the phenol in the ortho position to either the OH or OR1 group, and through a tertiary carbon atom of either a tertiary alkyl radical having 4 to 8 carbon atoms or a 1-methylcyclopentyl, methyl - 1 - methylcyclopentyl, 1 - methylcyclohexyl or methyl - 1 - methylcyclohexyl radical.  The synthetic rubber may be a polymer of butadiene 1,3-isobutene, or 2-chlorobutadiene - 1,3, or a copolymer thereof with acrylonitrile, styrene or methyl methacrylate.ALSO:A para alkoxy phenol, substituted by a tertiary hydrocarbon radical in ortho position to either the hydroxyl or the alkoxy group, and suitable for use as an antioxidant for natural or synthetic rubber (see Group V) may be prepared by reacting a p-alkoxyphenol with an olefine having 4 to 8 carbon atoms or 1-methylcyclopentene, methyl - 1 - methylcyclopentene, 1 - methylcyclohexene or methyl - 1 - methylcyclohexene in the presence of sulphuric acid or of a Friedel-Crafts catalyst, e.g. anhydrous zinc chloride.  A mixture of 2- and 3-(11 : 11 : 31 : 31-tetramethylbutyl) - 4 - methoxy - phenols is prepared by heating 5 parts p-methoxyphenol with 2.4 parts 96 per cent sulphuric acid, cooling the mixture, adding 33 parts p-methoxy phenol and then adding di-isobutylene with stirring at 45 DEG  to 50 DEG  C. for one hour.  The mixture is then heated with sodium carbonate and water and the product extracted with benzene.  A mixture of 2- and 3-a -methylcyclohexyl-4-methoxyphenols is obtained by stirring together 37.2 parts p-methoxyphenol and 2.4 parts 96 per cent sulphuric acid and adding 32 parts 1-methylcyclohexene at 50 DEG to 62 DEG  C.  The mixture is stirred for 1 hour, sodium carbonate and water added with further stirring, and the product extracted with benzene.  A mixture of 2- and 3-tert.-butyl-4-n-butoxy phenols is prepared by adding 6.75 parts di-isobutylene to a mixture of 20 parts p-n-butoxyphenol, and 0.6 parts 96 per cent sulphuric acid, stirring for a period, adding soda ash and water, and extracting the product with benzene.ALSO:Natural or synthetic rubbers, rubber articles, and latices are preserved by incorporating therein an antioxidant of the formula: <FORM:0763283/V/1> in which R1 is an alkyl radical and R2 is a tertiary hydrocarbon radical attached to the phenol in the ortho position to either the OH or OR1 group, and through a tertiary carbon atom of either a tertiary alkyl radical having 4 to 8 carbon atoms or a 1-methylcyclopentyl, methyl1-methylcyclopentyl, 1-methylcyclohexyl, or methyl-1-methylcyclohexyl radical.  The antioxidant may be prepared by reacting a p-alkoxyphenol with an olefine having 4 to 8 carbon atoms or 1-methylcyclopentene, methyl-1-methylcyclopentene, 1-methylcyclohexene or methyl-1-methylcyclohexene in the presence of sulphuric acid or a Friedel-Crafts catalyst, e.g. anhydrous zinc chloride.  The mixture of 2- and 3- substituted 4-alkoxyphenols obtained by this reaction may be used as an antioxidant or the components may be separated and used individually.  The synthetic rubber may p  comprise a polymer of butadiene 1, 3, isobutene, or 2-chlorobutadiene 1, 3, or a copolymer thereof with acrylonitrile, styrene, methyl methacrylate, or other known polymerizable compound. Examples are described illustrating the improved ageing qualities of natural rubber vulcanizates, some of which (for use in the white walls of tyres) contain titanium dioxide pigment, and utilizing as antioxidant (1) 2 tert. butyl-4 methoxyohenol and 3 tert-butyl-4-methoxyphenol either singly or in combination (2) 2 tert. butyl-4-ethoxyphenol and 3-tert. butyl-4-ethoxyphenol either singly or in combination (3) 2 tert.-amyl-4-methoxyphenol and 3 tert.-amyl-4-methoxyphenol either singly or in combination, (4) a mixture of 2- and 3-(11 : 11 : 31 : 31-tetra-methyl-butyl) - 4 - methoxyphenols, (5) a mixture of 2- and 3-d-methylcyclohexyl-4-methoxy-phenols, (6) a mixture of 2- and 3-tert.-butyl-4-n butoxyphenols, (7) a mixture of 2- and 3-tert.-butyl-4-methoxy-phenols.  As antioxidants are also specified 2- and 3-tert.-butyl-4-dodexyloxy-phenols and 2- and 3- methylcyclopentyl-4-methoxyphenols.  The preparation of the mixtures of (a) 2- and 3-(11 : 11 : 31 : 31 tetra-methylbutyl)-4-methoxyphenols (b) 2- and 3-a -methylcyclohexyl-4-methoxyphenols, and (c) 2- and 3-tert.-butyl-4-n-butoxyphenols, respectively, is described (see Group IV(b)).