GB853518A - Water-dispersed pressure-sensitive tape adhesives - Google Patents

Abstract

A pressure sensitive adhesive is prepared by forming a stable aqueous dispersion of a neutral tackifying resin in the form of an impalpable powder, and mixing it with a natural and/or synthetic rubber latex. The tackifying resin may be a terpene resin or pentaerythritol abietate. The synthetic rubber latex may consist of an aqueous dispersion of an butadiene-styrene copolymer. Antioxidants, fillers, dyes, pigments, and vulcanizing agents and accelerators may be incorporated in the blend, preferably as preformed aqueous dispersions. In an example an aqueous dispersion is prepared by agitating in an attrition mill a mixture of water, a powdered thermoplastic terpene resin, partially polymerized rosin, ammonium hydroxide, and 2,5-ditertiary amyl hydroquinone (as an antioxidant for the resin). The partially polymerized resin reacts with the ammonium hydroxide to form a water soluble soap serving as a dispersing agent, which on subsequent drying reverts to a water-insoluble tackifying resin. There is then separately prepared in the attrition mill an aqueous dispersion containing polymerized rosin or dehydroabietic acid, ammonium hydroxide, and 2,2 methylenebis(4 methyl-6-tertiarybutyl phenol) as rubber antioxidant. The two dispersion are blended with concentrated natural rubber latex to produce a composition containing (in parts by weight), rubber 100, neutral tackifying resin 89, soap forming resinous acids 5,6, antioxidants 4,8, ammonia 0,7, and water 151. An adhesive tape is produced by applying the adhesive to a surface of a tape of cellulose acetate, or a fibrous or paper sheet impregnated with synthetic rubber composition.