Toray Silicone Company Limited

Hiroshi Masaoka

Shosaku Sasaki

Yuji Hamada

A curable organopolysiloxane composition comprising an organopolysiloxane having higher alkenyl groups, an organohydrogenpolysiloxane crosslinker, and organopolysiloxane free of alkenyl groups and silicon-bonded hydrogen atoms, a platinum group metal-containing catalyst and an inhibitor therefor provides for the formation of a cured release film. When this composition is coated on the surface of any of various types of substrates, for example, paper, synthetic resin films, fibers, etc., and then heated for 10 to 20 seconds at 80 to 90 degrees Centigrade, it forms a cured film which manifests an extremely good release performance for tacky substances, such as, for example, pressure-sensitive adhesives, and the like, while at the same time evidencing an excellent adherence to the substrate itself. The compositions can be used with synthetic resin films, such as polyolefin, which are easily deformed by heat and with poorly heat-tolerant paper.

Organopolysiloxane composition for the formation of a release film

An adhesion promoter which is a silane or polysiloxane having in each molecule at least one organic group possessing aliphatic unsaturated group and at least one organic group possessing amino group or having in each molecule at least one organic group possessing both aliphatic unsaturation and an amino group is useful for improving the adhesion of radiation curable organopolysiloxane compositions to substrates.

Adhesion promoter method

A curable organopolysiloxane composition comprising an organopolysiloxane gum having higher alkenyl groups, an organohydrogenpolysiloxane crosslinker, a solvent, a platinum group metal-containing catalyst and an inhibitor therefor provides for the formation of a tough, cured release film. When this composition is coated on the surface of any of various types of substrates, for example, paper, synthetic resin films, fibers, etc., and then heated for 10 to 20 seconds at 80 to 90 degrees Centigrade, it forms a cured film which manifests an extremely stable release performance for tacky substances, such as, for example, pressure-sensitive adhesives, and the like, while at the same time evidencing an excellent adherence to the substrate itself. The compositions can be used with synthetic resin films, such as polyolefin, which are easily deformed by heat and with poorly heat-tolerant paper.

Organopolysiloxane composition for the formation of a cured release film

Adhesion promoter

The method of the present invention provides for the manufacturing of an alkenyl group-containing organopolysiloxane using an alkali catalyst in the presence of oxygen and in the absence of carbon dioxide. The copolymer is characterized by a viscosity of at least 500 cst at 25.degree. C., can be efficiently manufactured and is free of gelation. In the method an organopolysiloxane represented by the average formula R.sup.1.sub.a SiO.sub.(4-a)/2 in which R.sup.1 is a monovalent hydrocarbon group free of aliphatic unsaturation and a 4-8 carbon atom alkenyl group-containing organopolysiloxane represented by the average formula R.sup.2.sub.b R.sup.3.sub.c SiO.sub.(4-b-c)/2 are copolymerized.

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Saitama, Japan

Hiroshi Masaoka