GB991139A - Bonding rubbery polymers to siliceous surfaces and tires therefrom - Google Patents

Abstract

For the purpose of bonding rubber, synthetic rubber or other elastroneric materials to them, glass or other siliceous fibres are coated with a defined class of non-olefinic substituted alkyl, aralkyl or aryl silanes, preferably amino-propyl triethoxysilane, the rubbery material, then being cured in contact with, the fibres in the presence of a curing system comprising zinc oxide alone or in combination with one or more of magnesium oxide, a peroxide, a sulphur-containing accelerator, sulphur, or a quinone and an oxidizing agent to produce hoses, ropes, belts or tyres. The broad class of substituted alkyl, aralkyl or aryl silanes usable is given by the general formula <FORM:0991139/D1-D2/1> in which R is alkyl, aralkyl or aryl one or more hydrogen atoms in which is replaced by an amino, mercapto, carboxyl, cyano, hydroxy, epoxy, quinone, sulphonic, or oxime group, X is a group such as a halogen, hydroxy or ester group reactable with the siliceous surface, and Y and Z are both or either the same as orthepameas R, or an alkyl group, e.g. methyl. The preferred class has the following general formula:- (X)4-n-Si-(RNH2)n in which R is methylene or alkylene with 2-12 carbon atoms, X is any of halogen, hydroxy or alkoxy, and n is 2 or 3. Examples of synthetic rubbers are polyisoprene, polybutadiene, polybutadiene/acrylonitrile and/styrene, polychlorobrene, butyl rubber, chlorinated and brominated butyl rubber, and ethylene-propylene rubbery copolymers. Examples are given in which compositions of various rubbers containing compounding and vulcanizing ingredients are sheeted and bonded by vulcanizing to glass fabrics or tyre cords which have been coated with aminopropyl triethoxy silane dissolved in an organic solvent such as heptane and dried. In making tyres (Example I) chlorinated butyl rubber compositions used for tread, carcass, inner liner, bead insulation, and as a connecting coating for the coated glass fibre cords, all contain zinc oxide and magnesium oxide in addition to carbon blacks, stearic acid, antioxidants, benzothiazyl disulphide and tetramethyl thiuram disulphide. Zinc oxide and magnesium oxide are also contained in chlorinated butyl rubber and neoprene compositions to be bonded to both sides of glass fabric coated with amino-propyl-triethoxysilane by curing with dicumyl peroxide +Ex.II), but (Ex. IV) the zinc oxide above gives an effective bond, which is less effective if auxiliary agents such as zinc chloride, dicumyl peroxide and sulphur accelerators are used. Similar results are given with brominated butyl rubber (Ex. V). Magnesium oxide, with the zinc oxide, is found to be necessary for good bonding of natural rubber, NBR rubber and SBR rubber (Ex. VII). Butyl rubber compositions require for effective bonding according to the invention the use of a quinoid curing agent and an oxidizing agent such as red lead, in addition to zinc oxide, whether or not magnesium oxide is used (Ex. VIII). In Ex. IX a composition bound to glass fabric coated with amino propyl triethoxysilane comprises a terpolymer of ethylene 65 parts, propylene 33 parts, and norbornylene 2 parts, carbon black, zinc oxide, magnesium oxide, stearic acid, sulphur, tetramethyl, thiuram disulphide, mercapto benzthiazole and petroleum lubricating oil.