GB880284A - Adhesive compositions - Google Patents

Abstract

A normally-tacky pressure-sensitive adhesive composition for application to one or both sides of a backing comprises a curable elastomeric polymer, a tackifier compatible therewith, and a phenol-aldehyde resin made from an alkyl phenol the alkyl group of which contains at least 9 carbon atoms and is preferably a branched chain containing 9 to 15 carbon atoms; the resin may be present in an amount from 35 to 100 parts to 100 parts of polymer. The polymer may be natural or reclaimed rubber, butadiene-styrene copolymers containing at least 50% and preferably at least 70% butadiene, polybutadiene, butyl rubber, an isobutylene-isoprene copolymer, or a chloroprene polymer. Tackifiers specified are rosin, hydrogenated rosin, dehydrogenated rosin, or their glycols or glycerides, polyterpenes, coumarone-indene resin, or polyalkyl styrenes, these being used in an amount 25 to 125 parts to 100 parts of polymer. The resin is prepared by heating to 90 degrees for 2 hours the alkyl phenol and paraformaldehyde, preferably in the range of 1,1 to 1,5 moles of aldehyde per mole of phenol, in the presence of a trace of alkali (about 0,01 mole per mole of phenol); toluene is then added and refluxed for about 2 hours. The ingredients are mixed together with fillers, e.g. zinc oxide, magnesium carbonate, calcium carbonate, lead oxide, clay, titanium dioxide, aluminium, hydrated alumina, pulverized glass, or silica, and anti-oxidants, heat stabilizers, dyes, pigments, or plasticizers. The composition is applied to backing tapes of paper, cloth, or non-fibrous films coated, if desired, with a primer. Specification 865,383 is referred to.