Primer for the anchoring of conventional tacky and pressure sensitive adhesives to, in particular hydrophilic brackets, in particular for conventional adhesive films, adhesive strips and the like.

摘要

A pressure-sensitive adhesive tape or sheet having a hydrophilic backing, has a primer coating thereon comprising at least one elastomer and a titanate having the formula FORM:0861215/IV (a)/1 wherein R, R1, R11 and R111 are all alkyl radicals, and on the primer coating is a coating of a compatible normally tacky and pressuresensitive adhesive. The elastomer may consist of polyisoprene such as milled crude rubber, or a copolymer of butadiene and a monovinyl monomer such as styrene comprising at least 40% by weight of butadiene. The preferred titanate is either tetra-isopropyl or tetra-n-butyl titanate, but tetra-ethyl, tetra-pentyl, tetra-decyl, or tri-isopropyl-n-butyl titanate are mentioned as alternatives. Preferably the primer composition is prepared by dissolving a milled elastomer or mixture of elastomers in an organic solvent, and adding one part by weight of the titanate per 1 to 100 parts of elastomer. In the manufacture of the adhesive tape or sheet the composition may be applied to a hydrophilic tape or sheet as a coating of about 0.01 to 0.25 ounce dry weight per square yard, and dried for a short period at moderate temperatures. A pressure-sensitive adhesive compound may then be applied to the primed sheet or tape as a coating of about 0.5 to 5 ounces per square yard. The organic solvents in the primer and adhesive compositions are preferably the same or compatible. Both compositions may be applied to the sheet or tape by spraying, printing, knife coating, or reverse roll coating. The sheet or tape may consist of a film of regenerated cellulose, hydroxy alkyl cellulose ether, methyl cellulose, or a hydrophilic ethyl cellulose. In one of the described examples the primer composition is prepared by dissolving milled pale crepe rubber in toluene, and adding to the solution 0.5 parts by weight of tetra-isopropyl titanate per 99.5 parts of rubber. The primer composition is applied to a sheet of "Cellophane" (Registered Trade Mark) and is dried. There is then applied a pressure-sensitive adhesive composition comprising (in parts by weight) milled pale crepe 100, polybetapinene resin 75, petroleum oil 5, and polymerized trimethyl dihydroquinone 2, as a solution in heptane. In a further example the primer composition comprises 90 parts butadiene-styrene copolymer, and 10 parts tetra-butyl titanate, and in other examples it contains various proportions of pale crepe and tetra-isopropyl or tetra-butyl titanate. Three other pressure-sensitive adhesive compositions B, C and D are described, viz., solutions in toluene of (B) milled smoked sheet 100, zinc oxide 50, dehydrogenated rosin 75, sym. dibeta naphthyl para-phenylene diamine 2. and lanolin 100; (C) butadiene-styrene copolymer 50, smoked sheet 50, ester of hydrogenated rosin 50, polybetapinene rosin 16, polymerized trimethyl dihydroquinoline 2, and petroleum oil 20, and (D) polyvinyl ethyl ether resin 100, hydrogenated rosin 5, phenyl alpha-naphthylamine 0.35, and polyethylene glycol ricinoleate 1.5. Reference has been directed by the Comptroller to Specification 772,675.