Abstract: The invention provides a method for improving the stability of the surface-releasing performance of a silicone-coated release paper so as to minimize the changes in the peeling resistance between the release paper and an adhesive surface bonded thereto even after lapse of time from preparation of the release paper to bonding of the adhesive surface or from bonding of the adhesive surface to peeling thereof. The method comprises providing an overcoating layer of an organotin compound such as dibutyl tin diacetate on the surface of a cured coating layer of an organopolysiloxane composition comprising a vinyl-containing organopolysiloxane, an organohydrogenpolysiloxane and a platinum catalyst to promote the addition reaction between the silicon-bonded vinyl groups and the silicon-bonded hydrogen atoms.

Abstract: A solvent-free releasing silicone composition for rendering surfaces non-adherent which gives a cured film having desirable slip factor, toughness, and high-speed peel characteristics without sacrificing its inherenty merits such as curability, uniformity in peel resistance, and the residual adhesive strength employs a diorganovinylpolysiloxane having trivinylsilyloxy as one end group and either a vinyldimethylsilyl or trimethylsilyl group as the other end group.

Abstract: A releasing silicone composition comprising three ingredients including an organopolysiloxane having at least two specific organosiloxy units having an alkenyl group, a methylhydrogenpolysiloxane material, and a platinum catalyst.

Abstract: The inventive silicon-based coating composition provides an antistatic surface-releasing coating layer on a plastic film without the need of any antistatic undercoating. The coating composition comprises, in addition to the conventional ingredients in similar coating compositions including a vinyl-containing organopolysiloxane, an organohydrogenpolysiloxane and a platinum catalyst, a salt, e.g. nitrate and perchlorate, of a metal of the Ist, IInd or VIIIth Group of the Periodic Table and a specific organopolysiloxane having at least one per molecule of alkanolic pendant groups of the formula HO(CH.sub.2 CH.sub.2 O).sub.n CH.sub.2 CH.sub.2 CH.sub.2 --, in which n is 1 to 9.

Abstract: The invention provides a method for imparting releasability to the surface of a plastic film or paper by coating the surface with an organopolysiloxane composition followed by curing, in which the curing is complete by heating at a relatively low temperature and the cured surface film of the composition is very stable and free from the problem of transfer to another body in contact therewith. The composition comprises a vinyl-containing organopolysiloxane, an organohydrogenpolysiloxane and a platinum compound to catalyze the addition reaction between the silicon-bonded vinyl groups and silicon-bonded hydrogen atoms. Different from conventional organohydrogenpolysiloxane having a linear molecular structure, the organohydrogenpolysiloxane used in the invention is represented by the general unit formula (RSiO.sub.1.5).sub.m (RHSiO.sub.0.5).sub.n, in which R is a monovalent hydrocarbon group free form unsaturation and m and n are each a positive integer with the proviso that the ratio of n/m is from 0.1 to 3.

Abstract: So-called addition-type curable organopolysiloxane compositions curable by the hydrosilation reaction between vinyl groups of a dimethylpolysiloxane and hydrogen atoms directly bonded to the silicon atoms in a methylhydrogenpolysiloxane in the presence of a platinum catalyst can be imparted with a greatly increased pot life to have improved workability when the composition is admixed with a halogen- or alkoxy-substituted olefinic organic compound such as allyl halides, 1,3- and 2,3-dihalogenopropenes, 2-alkyl-3-halogenopropenes, 1,3- and 1,4-dihalogenobutenes-2 and alkyl allyl ethers as a moderator of the crosslinking reaction without any adverse effect on the curability of the composition.

Abstract: The invention provides a novel photocurable organopolysiloxane composition having an unusually high photosensitivity suitable, for example, for providing an anti-sticking layer on a release paper. The composition comprises an organopolysiloxane having, in a molecule, at least one thioacyloxy-containing organosiloxane unit as the photosensitive functional group and a photosensitizer. Further improved photocurable composition of the invention comprises an organopolysiloxane having, in addition to the above mentioned thioacyloxy-containing organosiloxane units, at least one mercaptohydrocarbyl-containing organosiloxane unit in a molecule. Alternatively, photosensitivity of the similar degree is obtained when the composition comprises a first organopolysiloxane having, in a molecule, at least one thioacyloxy-containing organosiloxane unit and a second organopolysiloxane having, in a molecule, at least one mercaptohydrocarbyl-containing organosiloxane unit as combined.

Abstract: A novel photocurable composition suitable for preparing, for example, release papers is proposed which is formulated with photocrosslinkable organopolysiloxanes necessitating no conventional photosensitizers. Thus, the composition comprises(a) an organopolysiloxane having at least two mercaptoalkyl, e.g. mercaptopropyl, groups bonded to the silicon atoms in a molecule,(b) an organopolysiloxane having at least two alkenyl, e.g. vinyl groups directly bonded to the silicon atoms in a molecule, and(c) an organopolysiloxane having at least one benzoin group ##STR1## where Ph is a phenyl group, bonded to the silicon atom in a molecule, which component (c) serves as a photosensitizing ingredient.

Abstract: The invention provides a novel class of organopolysiloxane compounds having at least one benzoin group represented by the general formula ##STR1## in which Ph is a phenyl group and R is a hydrogen atom or an alkyl group, bonded to the silicon atom in a molecule. The benzoin-bonded organopolysiloxane compounds can readily be prepared by the dehydrohalogenation, dehydrogenation, dehydration or dealkoholation condensation reaction between a corresponding organopolysiloxane having silicon-bonded halogen atoms, hydrogen atoms, hydroxy groups or alkoxy groups and an .alpha.-substituted or unsubstituted benzoin compound in the presence of a suitable reaction promotor or a condensation catalyst.