Shin-etsu Chemical Co., Ltd.

Koji Yokoo

Masatoshi Arai

Yoshio Inoue

Takeo Inoue

Shinichi Sato

Tsuneo Kimura

Hitoshi Kinami

Takehide Okami

Mamoru Teshigawara

Masatoshi Miyake

Keisuke Imai

Masaharu Sato

Yoshio Inouye

Yoshifumi Kurihara

A method for preparing a room temperature curing organopolysiloxane composition having good working properties, which comprises (A) a diorganopolysiloxane having at least two hydroxyl groups bonded to silicon atoms in one molecule, (B) a thixotropy improver, (C) a finely divided silica powder, (D) at least one member selected from organosilanes having two or more ketoxime groups bonded to a silicon atom in one molecule and partial hydrolyzates thereof, (E) a curing catalyst for the condensation curing reaction between (A) and (D) components, and (F) an amine-based silane coupling agent for imparting adhesiveness to the composition, wherein the (A), (B) and (C) components are first mixed, with which the (D) and (E) components are further mixed, and the (F) component is finally added to and mixed with the resultant mixture.

Process for preparing a room temperature curing organopolysiloxane

In an RTV organopolysiloxane composition comprising a hydroxy-terminated diorganopolysiloxane and an organic silicon compound having at least three hydrolyzable groups, there is blended calcium carbonate which has been treated with 1-2.5% by weight of an agent having a melting or softening point of at least 100.degree. C. or a saturated fatty acid having at least 21 carbon atoms. The composition is adhesive to even surface treated aluminum plates and maintain a firm bond under water immersion and at elevated temperatures.

RTV organopolysiloxane compositions

A room temperature vulcanizable organopolysiloxane composition comprising a diorganopolysiloxane blocked with a hydroxyl group at opposite ends of the molecular chain of the diorganopolysiloxane, a silane or siloxane compound having at least three hydrolyzable groups in the molecule, a filler, and a curing catalyst. The composition further comprises a specific type of amide compound whereby the composition is readily released from electric or electronic parts after having been vulcanized and dipped in a hot soldering bath.

Room temperature vulcanizable organopolysiloxane composition for masking

A room temperature vulcanizable organopolysiloxane composition is provided, comprising (a) a diorganopolysiloxane blocked with a silanol, dialkoxy or trialkoxy radical at both ends of the molecular chain thereof, (b) a novel organic silicon compound of the general formula: ##STR1## wherein R.sup.1 is hydrogen or a monovalent hydrocarbon radical having 1 to 8 carbon atoms, ##STR2## m and l are independently equal to 0, 1 or 2, and n is an integer in the range of 2 to 8, and (c) a curing catalyst. The composition may further contain (d) an organoalkoxysilane.

The essential components in the inventive room temperature-curable organopolysiloxane composition are: (A-1) a diorganopolysiloxane of which each terminal silicon atom has a silanolic hydroxy group or two alkoxy groups; (A-2) a filler; (A-3) an alkenyloxy silane, e.g. methyl tri)isopropenyloxy)silane; (A-4) a guanidino-containing organosilicon compound, e.g. 3-(tetramethylguanidino)propyl trimethoxy silane; (A-5) an alcohol, e.g. methyl or ethyl alcohol; (B) an organosilicon compound having a silicon-bonded hydrogen atom; and (C) an organic tin compound as a catalyst. By virtue of the unique formulation above, the composition is very stable in storage in a moisture-free condition for a long period of time without losing the high curability when exposed to a moisture-containing atmosphere.

Room temperature-curable organopolysiloxane composition

The room temperature-curable organopolysiloxane composition of the invention is imparted with greatly improved stability in prolonged storage without being affected in respect of the curability. The composition is formulated, in addition to the base ingredients of a silanol- or alkoxy-terminated diorganopolysiloxane and a filler, with an alkenyloxy-containing silane compound in an amount of at least equimolar to the silanol groups and water in the base ingredients and a guanidino-containing organosilane compound in a limited amount.

The invention provides a room temperature-curable organopolysiloxane composition curable into a rubbery elastomer, which has excellent storage stability under a moisture-free condition without losing high curability. The composition comprises, in addition to the conventional essential ingredients of a hydroxy- or alkoxy-terminated diorganopolysiloxane, filler, triisopropenyloxy silane compound as a crosslinking agent and a guanidino-containing organosilicon compound as a curing aid, an amino-containing silane compound such as MeSi[NH--C.sub.3 H.sub.6 --Si(OEt).sub.3 ].sub.3 and MeSi[NH--C.sub.2 H.sub.4 NHC.sub.3 H.sub.6 --Si(OMe).sub.3 ].sub.3.

The room temperature-curable organopolysiloxane composition of the invention capable of giving a cured rubber can be used advantageously as an insulating material in electric and electronic instruments without causing troubles in contact points which is unavoidable with conventional compositions. The inventive composition is formulated with (a) a diorganopolysiloxane terminated at the molecule molecular chain ends each with a silanolic hydroxy group, (b) an alkenyloxy, e.g. isopropenyloxy, containing silane and (c) a guanidino-substituted organosilicon compound and these components are specified either by the upper limit of the content of low molecular constituents having a specified vapor pressure or higher or the upper limit of the vapor pressure of the compound per se so that the electric contact points near the insulation with the composition are free from exposure to the vapor of organosilicon compounds which may be deposited as an oxide of silicon by sparks.

The room temperature-curable organopolysiloxane composition of the invention can be cured into a rubbery elastomer which exhibits strong adhesion to the surface of a substrate made of, for example, a plastic resin even without the use of a primer or other adhesion aid. The composition comprises, in addition to the conventional ingredients of a silanolic hydroxy-terminated diorganopolysiloxane and alkoxy-containing organosilicon compound, a special organosilicon compound having, in a molecule, at least one group of the formula

The room temperature-curable organopolysiloxane composition of the invention is characteristic in the remarkably increased adhesive bonding strength of the rubber of the composition to the surface of a substrate of metals, plastics and others on which the composition has been cured. The composition is also advantageous in the improved thixotropy despite the admixture of an adhesion improver mentioned below. Thus, the composition comprises, in addition to conventional components in a deacidification type room temperature curable organopolysiloxane composition, a specific organic silicon compound represented by the general formula

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Tomioka, Japan

Koji Yokoo