A base composition for forming a release coating composition is disclosed. The base composition comprises (A) a silicate resin that is a liquid at 25° C. in the absence of any solvent. The (A) silicate resin includes an average of at least one silicon-bonded ethylenically un saturated group per molecule. The composition further comprises (B) an organopolysiloxane including an average of at least two silicon-bonded ethylenically un saturated groups per molecule. The (A) silicate resin is miscible with the (B) organopolysiloxane in the absence of any solvent. A method of preparing the base composition and a method of preparing a release coating composition are also disclosed.

Provided is a hydrosilylation reactive composition that has a sufficient pot life at room temperature, that can be cured at low temperature by exposure to high energy radiation, and that produces a stable semi-cured product during the curing process, and to provide a semi-cured product and a cured product obtained using this hydrosilylation reactive composition. The composition comprises: (A) a compound containing at least one aliphatically unsaturated monovalent hydrocarbon group in the molecule; (B) a compound containing at least two hydrogen atoms bonded to silicon atoms in the molecule; (C) a first hydrosilylation catalyst exhibiting activity in the composition without exposure to high energy radiation; and (D) a second hydrosilylation catalyst not exhibiting activity unless exposed to high energy radiation, and exhibiting activity in the composition by exposure to high energy radiation.

Provided is an adsorption temporary fixing sheet having a sufficient shear adhesive strength in a direction parallel to its surface, and having a weak adhesive strength in a direction vertical to the surface. Also provided is a method of producing such adsorption temporary fixing sheet. The adsorption temporary fixing sheet includes a foam layer including an open-cell structure, wherein, when a silicon chip vertical adhesive strength of a surface of the foam layer after 20 hours at each of such different temperatures as −40° C., 23° C., or 125° C. is represented by V1 (N/1 cm□), V2 (N/1 cm□), or V3 (N/1 cm□) and when a silicon chip shearing adhesive strength of the surface of the foam layer after 20 hours at each of the different temperatures (−40° C., 23° C., or 125° C.) is represented by H1 (N/1 cm□), H2 (N/1 cm□), or H3 (N/1 cm□), relationships of V1<H1, V2<H2, and V3<H3 are satisfied.

A silicone gel composition of the present invention contains the following components; A 100 parts by mass of an organopolysiloxane that is curable by an addition reaction; B. 0.01 to 10 parts by mass of an unsaturated hydrocarbon compound having one alkenyl group per molecule; and C. an addition reaction curing catalyst in a catalytic amount. The unsaturated hydrocarbon compound is at least one selected from the group consisting of an a-olefin that is liquid at room temperature (25° C.) and does not volatilize or decompose at 100° C. and α-methylstyrene. A silicone gel sheet of the present invention is obtained by molding the silicone gel composition into a sheet, and curing the sheet.

A defoamer or anti-foam formulation and a process for preparing the same. The process includes in a first step, preparing branched organopolysiloxanes (A) by irradiating organopolysiloxanes (X) of the formula (1)

R.sup.1.sub.3-a(R.sup.2O).sub.aSi—[OSiR.sup.3.sub.2].sub.n—OSi(OR.sup.2).sub.aR.sup.1.sub.3-a   (1).

Where with high-energy radiation, the viscosity of the organopolysiloxanes (A) is at least 40% higher than the viscosity of the organopolysiloxanes (X). In a second step, the branched organopolysiloxanes (A) are treated with a filler (B) which is selected from precipitated and/or fumed silicas, and organopolysiloxane resins (C).

A heat-conductive resin composition containing an inorganic filler component and a resin component, wherein the inorganic filler component includes first and second inorganic fillers, a particle size distribution has a first maximum point caused by the first inorganic filler and a second maximum point caused by the second, the diameter at the first maximum point is 15 μm or more, the diameter at the second is ⅔ or less that at the first, an integrated amount of frequency between a peak start and end in a peak having the first maximum point is 50% or more, and the first inorganic filler is formed by agglomerating hexagonal boron nitride primary particles and has a crushing strength of 6 MPa or more. The heat dissipation sheet is obtained by molding the heat-conductive resin composition.

A heat dissipation sheet having excellent thermal conductance, is a molded thermally conductive resin composition prepared by blending an inorganic filler component and a resin component, wherein the inorganic filler component particle size distribution includes a first maximum point attributable to the first inorganic filler and a second maximum point attributable to the second inorganic filler; the particle size at the first maximum point is 15 μm or more; the particle size at the second maximum point is ⅔ or less the particle size at the first maximum point; and an accumulated amount of the frequency between the peak start and the peak end of the peak having the first maximum point is 50% or more, and which has a surface roughness of from 1.5 to 3.0 μm and a thickness of 0.2 mm or less.

Provided is: a multicomponent curable thermally conductive silicone gel composition which has a high thermal conductivity, has excellent gap-filling ability and repairability, and has superior storage stability; a thermally conductive member comprising the composition; and a heat dissipating structure using the same. The thermally conductive silicone gel composition comprises: (A) an alkenyl group-containing organopolysiloxane; (B) an organohydrogenpolysiloxane; (C) a catalyst for hydrosilylation reaction; (D) a thermally conductive filler; (E) a silane-coupling agent or a hydrolysis condensation product thereof; and (F) a specific organopolysiloxane having a hydrolyzable silyl group at one end thereof. The thermally conductive silicone gel composition includes (I) a liquid composition that includes components (A), (C), (D), (E), and (F), but does not include component (B) and (II) a liquid composition that includes components (B), (D), (E), and (F), but does not include component (C) which are individually stored.

An object is to provide a heat conductive sheet having good handleability when mounting between the heating element and the heat dissipator, and softness that enables the distortion of the heating element, the heat dissipator, and the like to be suppressed in use. The heat conductive sheet contains: a matrix comprising a cured product of organopolysiloxane; and heat conductive fillers comprising anisotropic fillers with their major axes oriented in the thickness direction, and has a load property P represented b formula (1) below of 0.1 to 0.7: Load property P=(F.sub.30−F.sub.20)/F.sub.10 (1) wherein F.sub.10 is a load of the heat conductive sheet at 10% compression, F.sub.20 is a load of the heat conductive sheet at 20% compression, and F.sub.30 is a load of the heat conductive sheet at 30% compression.

Provided is a thermally conductive silicone composition that can be turned into a lightweight cured product superior in thermal conductivity, and is easily processable due to its low viscosity. The composition contains: (A) an organopolysiloxane having at least two alkenyl groups per each molecule; (B) an organohydrogenpolysiloxane having, per each molecule, at least two hydrogen atoms directly bonded to silicon atoms; (C) a thermally conductive filler containing magnesium oxide (20 to 40% by mass), aluminum oxide (40 to 60% by mass) and aluminum hydroxide (10 to 30% by mass); (D) a dimethylpolysiloxane with one end of the molecular chain thereof being blocked by a trialkoxy group; (E) a platinum group metal-based curing catalyst; and (F) an addition reaction control agent.