GB678588A - Improvements in and relating to pressure sensitive adhesive sheets - Google Patents

Abstract

In the manufacture of pressure-sensitive adhesive sheets, a minor proportion of a specific deactivator having the property of reducing the adhesion of the adhesive mass to materials having hydrophilic characteristics much more than its adhesion to materials having hydrophobic characteristics, and being (1) surface active, (2) a water-insoluble and oil-soluble emulsifier of the water-in-oil type, (3) a material having a solidification point above - 10 DEG C., and (4) dispersible in the adhesive mass, is incorporated therein, the adhesive mass being coated on a backing having hydrophilic characteristics. The backing may be pre-coated with a primer or subbing coat. The following specific deactivators are mentioned: diethylene glycol oleate; diethylene glycol stearate; glycerol monostearate; pentaerythritol monostearate; phospholipids such as lethicin, cephalin and sphingomyclin; polyethylene glycol (di-, tri-) ricinoleate; propylene glycol monostearate; sorbitan monostearate; and the stearylamine salt of the stearyl amide of orthophosphoric acid ethyl ester, having the formula <FORM:0678588/IV (a)/1> The specific deactivator may constitute from about one-eighth of 1 per cent to 5 per cent by weight of the adhesive mass, which may be of any normally tacky and pressure-sensitive kind, e.g. one based on relatively non-polar elastomers such as natural rubber, polyisoprene, the vulcanizable elastomeric copolymers and interpolymers of at least 40 per cent butadiene and at least 10 per cent styrene or an interpolymer of octyl acrylate, ethyl acrylate and vinyl acetate, or polyvinyl ethyl ether, to which may be added tackifiers such as rosin, hydrogenated or dehydrogenated rosin, the glycols and glycerides of these materials, polyterpenes, coumarone indene resins, polyalkyl styrenes or oil-soluble phenol aldehyde resins, fillers such as zinc oxide, magnesium carbonate, calcium carbonate, lead oxide, clay, titanium dioxide, aluminium, hydrated alumina, pulverized glass or silica, antioxidants, e.g. diamyl or dibutyl hydroquinone, or phenyl-alpha-naphthylamine or heat stabilizers, dyes or pigments. A small quantity of a stable oil, e.g. soybean oil or mineral oil, may be added to improve unwinding characteristics. In examples, adhesive masses are formed by mixing solutions of the various ingredients in aliphatic or aromatic solvents. Specifications 608,127, [Group VIII], and 611,211, and U.S.A. Specifications 2,340,298, 2,397,774, 2,405,926, 2,410,053, 2,415,901 and 2,424,996 are referred to.