Stratum having release properties and method of making

Claim 1

A pressure-sensitive adhesive tape in which a sheet backing is provided, on one surface, with a layer of normally tacky and pressure-sensitive adhesive and on the other surface with a low adhesion backsize which is the solid, crosslinked, substantially insoluble joined interpenetrating polymeric network reaction product of starting materials consisting essentially of (1) 98-50 parts by weight of a first moiety terminated with from more than 1 to not more than 3 isocyanate groups, liquid at 60° C., having an NCO equivalent weight of at least about 100, containing not more than 5 urethane or urea gram equivalents per 1000 grams of said moiety, and formed by reacting one or more polyisocyanates with one or more diols, triols, diamines or triamines, and (2) correspondingly 2-50 parts by weight of an organosilicone second moiety which is a silane-modified OH-endblocked predominantly dimethyl-substituted linear polysiloxane, is liquid at 20° C., and has a plurality of active hydrogen atoms each chemically bonded to a nitrogen or oxygen atom attached to a CH 2 group which is at least 3 carbon atoms distant from the nearest silicon atom, said nitrogen or oxygen atoms constituting no more than about 4% by weight of said organosilicone moiety.

Claim 6

The method of making a self-supporting sheet material capable of being wound convolutely upon itself in roll form, said sheet material affording accurately predictable and controllable release for a wide variety of normally tacky and pressure-sensitive adhesives, which method includes the steps of: a. blending together in a mutually compatible solvent system components consisting essentially of 1. 98-50 parts by weight of a first moiety terminated with from more than 1 to not more than 3 isocyanate groups, liquid at 60° C., having an NCO equivalent weight of at least about 100, containing not more than 5 urethane or urea gram equivalents per 1000 grams of said moiety, and formed by reacting one or more polyisocyanates with one or more diols, triols, diamines or triamines, and 2. correspondingly 2-50 parts by weight of a second organosilicone moiety which is a silane-modified OH-endblocked predominantly dimethyl-substituted linear polysiloxane, is liquid at 20° C. and has a plurality of active hydrogen groups each chemically bonded to a nitrogen or oxygen atom attached to a CH 2 group which is at least 3 carbon atoms distant from the nearest silicon atom, said active hydrogen bearing atoms constituting no more than about 4% by weight of said organosilicone moiety, thereby forming a pourable liquid, b. coating the pourable liquid in a thin stratum upon a substrate, c. drying to remove the solvent, and d. reacting the moieties.

Claim 7

The method of making a self-supporting sheet material capable of being wound convolutely upon itself in roll form, said sheet material affording accurately predictable and controllable release for a wide variety of normally tacky and pressure-sensitive adhesives, which method includes the steps of: a. blending together in a mutually compatible solvent system components consisting essentially of 1. 98-50 parts by weight of a first moiety terminated with from more than 1 to not more than 3 isocyanate groups, liquid at 60° C., having an NCO equivalent weight of at least about 100, containing not more than 5 urethane or urea gram equivalents per 1000 grams of said moiety, and formed by reacting one or more polyisocyanates with one or more diols, triols, diamines or triamines, and 2. correspondingly 2-50 parts by weight of a second organosilicone moiety which is a silane-modified OH-endblocked predominantly dimethyl-substituted linear polysiloxane, is liquid at 20° C. and has a plurality of active hydrogen groups each chemically bonded to a nitrogen or oxygen atom attached to a CH 2 group which is at least 3 carbon atoms distant from the nearest silicon atom, said active hydrogen bearing atoms constituting no more than about 4% by weight of said organosilicone moiety, thereby forming a pourable liquid, b. coating the pourable liquid in a thin stratum upon a substrate, c. drying to remove the solvent, and d. reacting the moieties.