Stable silicone-coated release liner for pressure-sensitive adhesive sheets

A release liner which, even after exposure to natural or artificial light in the presence of moisture vapor, displays release properties of less than 20 g/cm width with respect to normally tacky and pressure-sensitive adhesive tape, said liner comprising a self-supporting sheet material having bonded to at least one face, a thin layer comprising noble metal and cured silicone polymer having substantially no residual ethylenic unsaturation and being the platinum-catalyzed reaction product of solvent-free liquid components consisting essentially of

• (1) terminally unsaturated polydimethylsiloxane having the structural formula ##STR19## in which a is 2, 3, or 4, b is 15-100, R and R.sup.1 are monovalent hydrocarbon radicals free of aliphatic unsaturation, at least 50 mole percent of said radicals being methyl and the remainder being alkyl, cycloalkyl, aryl or aralkyl, and R.sup.2 is a monovalent ethylenically unsaturated aliphatic hydrocarbon radical having 2 to 6 carbon atoms and
• (2) polymethylhydrosiloxane crosslinking agent having the empirical formula
• R.sup.3.sub.c H.sub.d SiO.sub.(4-c-d)/2
• in which R.sup.3 is bonded to a silicon atom and is a monovalent aliphatic or aromatic hydrocarbon radical or the halogenated derivative of such a radical, c is 0 to 3, and d is 0.005 to 2.0, the sum of c plus d being 0.8 to 3, there being at least 2 silicon-bonded hydrogen atoms present per molecule,
• the ratio of silicon-bonded hydrogen in (2) to silicon-bonded ethylenically unsaturated radicals in (1) being from 1:1 to 20:1.