Toray Silicone Company Limited

Dow Corning Toray Silicone Company Limited

Shosaku Sasaki

Nobuo Kaiya

Hiroshi Masaoka

Yuji Hamada

Akihiko Shirahata

Ichiro Murakami

Masushi Hayashi

Takateru Yamada

Keiichi Kishimoto

Masahiko Suzuki

Yoshinobu Koda

Masamitsu Tanimura

The instant invention pertains to an organopolysiloxane composition for the formation of a cured release film wherein said organopolysiloxane composition cures rapidly under exposure to ultraviolet radiation to form a cured film that tightly adheres to various types of supports or base materials. The organopolysiloxane composition for the formation of a cured release film of the instant invention is comprised of (A) an organopolysiloxane that contains in each molecule at least 2 higher alkenyl groups as represented by the general formula

Organopolysiloxane composition for the formation of a cured release film

The instant invention pertains to an organopolysiloxane composition for the formation of a release film, that has a high curing rate at relatively low temperatures (.ltoreq.100.degree. C.) and that forms a cured film that both adheres strongly to various types of substrates and is highly releasing for tacky or sticky substances. The organopolysiloxane composition for the formation of a cured release film of the instant invention comprises (A) organopolysiloxane that contains in each molecule at least 2 alkenyl groups with the general formula H.sub.2 C.dbd.CH--(CH.sub.2).sub.n --, wherein n=2 to 8; (B) an organohydrogenpolysiloxane that contains in each molecule at least 2 silicon-bonded hydrogen atoms and at least 1 alkenyl group with the general formula H.sub.2 C.dbd.CH--(CH.sub.2).sub.n --, wherein n=2 to 8; (C) an addition-reaction inhibitor; (D) platinum group metal catalyst; and optionally (E) a nonreactive organopolysiloxane that contains neither silicon-bonded alkenyl nor silicon-bonded hydrogen.

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

A pressure-sensitive adhesive having an excellent tack and adhesive strength is obtained from a composition which contains an alkenyl group-containing silicone polymer, a tackifying silicone resin having less than one percent hydroxyl content, an organohydrogenpolysiloxne curing agent for the alkenyl group-containing silicone polymer and a platinum-containing catalyst. The composition can be cured to a silicone pressure-sensitive adhesive by heating at relatively low temperatures.

Silicone pressure-sensitive adhesive composition

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.

Adhesion promoter

Hot-bonding silicone adhesive composition prepared by kneading and heating a mixture of a polydiorganosiloxane and a microparticulate silica and then adding an arbitrary amount of a solvent and an organopolysiloxane resin to the kneaded and heated mixture. The composition has substantially no tack at room temperature when freed of its solvent; however, it has high adhesive strength at elevated temperature.

Hot-bonding silicone adhesive composition

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.

Method for manufacturing an alkenyl group-containing organopolysiloxane

An adhesive release composition containing specific amounts of an organopolysiloxane bearing oxyalkylene groups and alkenyl groups, an organohydrogenpolysiloxane, and a platinum-type catalyst is characterized by the formation, on various base surfaces, of a release surface having an excellent printability and a stable release force. For example, a roll of pressure sensitive adhesive tape of this invention can be easily unrolled, durably adhered to an article and clearly printed with ink on its adhesive-releasing surface which bears the release composition of this invention.

Release composition

A release agent composition which manifests almost no silicone migration and a very low slickness while nevertheless having a low release value is achieved by means of a release agent composition which is based on a methylalkenylpolysiloxane, an alkylhydrogenpolysiloxane crosslinker for the methylalkenylpolysiloxane, an organopolysiloxane containing monovalent hydrocarbon groups which lacks aliphatically unsaturated bonds and which contains 6 to 18 carbon atoms which functions to lighten the releaseability of the cured film, to check silicone migration, and to reduce the slickness, and a catalytic quantity of a platinum-type catalyst.

Release agent composition

A method of curing certain organopolysiloxane compositions by a combination of heat and exposure to ultraviolet radiation or electron beam provides the ability to use lower temperatures than heat cures alone and shorter cure times than ultraviolet radiation or electron beam alone. The organopolysiloxane compositions are addition-curable and are made up of alkenyl-containing organopolysiloxane, organohydrogensiloxane, a platinum catalyst, an addition-reaction inhibitor selected from alkynol, 3-methyl-3-pentene-1-yne, 3,5-dimethyl-3-hexene-1-yne, methylvinylsiloxane cyclics, benzotriazole, and mixtures thereof, and a photosensitizer.

Method for curing organopolysiloxane compositions and the compositions

Releasable film forming compositions

Room temperature-storable, heat-curable organopolysiloxane compositions which comprise silicon-bonded vinyl radicals, silicon-bonded hydrogen atoms, a platinum-type compound and an unsaturated hydrocarbon compound of the conjugated ene-yen type provide a realease surface for tacky substances when coated onto the surface of a base material and heated, even mildly. The release surface possesses a time-stable release ability, particularly for pressure sensitive adhesive bearing articles such as tapes and labels.

Peellable film-forming organopolysiloxane compositions

The present invention provides a releasable film forming composition comprising (1) an organopolysiloxane having hydroxyl groups at the ends of the molecular chain, (2) a finely divided silica, (3) a phenyl-containing organosilane or organopolysiloxane, (4) an organohydrogenpolysiloxane containing at least three SiH groups per molecule, (5) a metallic salt of an organic acid and (6) an organic solvent, and a process for preparing same, as well as a releasable film forming composition comprising (1) an organopolysiloxane containing at least two silicon atom-bonded alkenyl groups per molecule, (2) a finely divided silica, (3) a phenyl-containing organosilane or organopolysiloxane, (4) an organohydrogenpolysiloxane containing at least two SiH groups per molecule, (5) a platinic compound and (6) an organic solvent, and a process for preparing same. These compositions exhibit a superior printability and a stable releasability from adhesive materials and are less slippery.

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Chiba, Japan

Shosaku Sasaki