Pressure-sensitive adhesive tape

Coating compositions comprise an alcohol-soluble urea-, thiourea- or melamine-aldehydemonohydric alcohol resin and a plasticizer therefor such as a castor oil-modified alkyd resin or heavy-bodied castor oil; optionally, ethyl cellulose, polyvinyl butyral, dipentamethylene thiuram tetrasulphide, fillers, e.g. zinc oxide, volatile solvents such as xylol, butanol, ethyl alcohol, pigments or dyes may be incorporated in the compositions. When the coating compositions are applied to fibrous sheet materials, the sheet material may be impregnated with a composition comprising one or more of the following resins: rosin, ester gum, polymerized rosin, zinc abietate, limed rosin, hydrogenated rosin, pentaerythritol abietate, coumarone-indene, hydrogenated coumarone - indene, depolymerized butadienestyrene copolymer, together with vulcanizing agents and accelerators such as zinc oxide, dipentamethylene or pentamethylene thiuram tetrasulphide, oil-soluble phenol-aldehyde resins, alkyl phenol sulphide dispersed in oleum spirits and tetramethyl-thiuram-disulphide. The depolymerized butadiene-styrene copolymers may be made by mixing the copolymer with p-hydroxy-phenyl-morpholine, zinc oxide and zinc xylyl mercaptan, and heating the mixture with steam under pressure. If desired, the zinc xylyl mercaptan may be replaced by phenol hydrazine. The castor oil-modified alkyd resin may be made by heating together (1) ethylene glycol, glycerine, castor oil and an addition product of a terpene and maleic anhydride; (2) ethylene glycol, phthalic anhydride, glycerine and castor oil. The compositions are used in the preparation of pressure-sensitive adhesive tapes.