| 摘要 |
<p>An adhesive composition comprises a reinforced ester of a copolymer containing substantially equimolecular proportions of maleic anhydride and a vinyl ether or styrene or a ring-substituted styrene (e.g. methyl styrene), said copolymer having an intrinsic viscosity of 0.2 to 2 in cyclohexanone, said vinyl ether being a C1 to C8 alkyl vinyl ether wherein the vinyl group may be a -substituted with an inert substituent, at least 65 per cent of the carboxyl groups of the copolymer being esterified with a primary C6 to C16 aliphatic monohydric alcohol, and wherein the ester is of plasticity not greater than 4 mm. and is reinforced by cross-linking or by mixing with a reinforcing agent. The vinyl ether may be methyl, ethyl, propyl, isopropyl, butyl or isobutyl vinyl ether and specified alcohols are n- or iso-octyl, n-nonyl, n- or branched chain decyl, nundecyl, n-hexyl, lauryl and tridecyl alcohols and a named mixture containing a high proportion of branchedchain decyl alcohol. The esters may be prepared by heating the alcohol with a dispersion of the copolymer in a diluent, such as xylene, toluene or diethyl benzene, in the presence of a catalyst, e.g. p-toluene sulphonic acid, benzene sulphonic acid or sulphuric acid, and optionally a stabilizer (e.g. 2,5-ditertiarybutylhydroquinone or 2,6-ditertiarybutyl-p-cresol). The ester goes into solution and may be recovered by precipitation with methanol or acetone. Plasticity of the ester may be further increased (cold flow resistance increased) by (a) the crosslinking, e.g. to a gel content of 10 per cent; (b) addition of the reinforcing agents; or (c) incorporation of a copolymer ester which has previously been cross-linked. Cross-linking may be effected by (i) polyvalent metal oxides such as zinc oxide, titanium dioxide or aluminium hydrate; (ii) initiating a chain-type reaction with a peroxide catalyst such as benzoyl, dichlorobenzoyl or di-t-butyl peroxide; or (iii) di- or tri-hydroxy alcohols such as ethylene and propylene glycols, diethylene and dipropylene glycols and glycerol. Methods (i) and (ii) may be used together. The reinforcing agents may be elastomers such as polyvinyl ethyl or isobutyl ether, butadiene/styrene copolymer, polyisobutylene or polyethylacrylate, or may be finely divided materials such as carbon black, silica gel, calcium carbonate or calcium salicylate. The products stick to unprimed film, e.g. ethyl cellulose, cellulose acetate, regenerated cellulose, polyvinyl chloride and polyethylene glycol terephthalic acid, and to cloth or waterproofcloth and are thus suitable as pressure-sensitive adhesives and as surgical dressings. Coatings on glass or metal may also be provided and laminates such as plywood or glass fibre lamin ates may be obtained. Some of the productsmay be moulded. The copolymers used may be prepared in a monomer solvent such as xylene or benzene using a catalyst such as benzoyl peroxide, and in Example (1) the styrene which contains the catalyst is added dropwise throughout the polymerization.</p> |
