Provided is a silicone composition having components (A) to (E):100 parts by mass of (A) a linear, branched, or network organopolysiloxane having a vinyl value of 0.01 mol/100 g or more and 0.04 mol/100 g or less and a viscosity of 100 mm.sup.2/sec or more and 500 mm.sup.2/sec or less at 25° C., wherein each of terminals of the organopolysiloxane has one or more alkenyl groups; 0.01 to 3 parts by mass of (B) a linear, branched, or network organopolysiloxane having a vinyl value of 0.2 mol/100 g or more and 1.2 mol/100 g or less and a viscosity of 2 mm.sup.2/sec or more and 60 mm.sup.2/sec or less at 25° C., wherein each of terminals of the organopolysiloxane has one or more alkenyl groups; (C) an organohydrogenpolysiloxane having an amount of 1 mol/100 g or more and 2 mol/100 g or less of an SiH group, wherein a ratio of the number of the SiH group in component (C) to a total number of the alkenyl groups in components (A) and (B) is 1 to 5; 0.01 to 10 parts by mass of (D) an addition-reaction control agent, relative to total 100 parts by mass of components (A), (B), and (C); and a catalytic amount of (E) a platinum group metal catalyst.

A one-pack type curable silicone gel composition which contains: 100 parts by mass of (A) a branched chain organopolysiloxane having a specific structure from 0.1 part by mass to 50 parts by mass of (B) a diorganopolysiloxane having both molecular chain ends blocked with diorganohydrogensiloxy groups; (C) a platinum-based catalyst; and (D) a phosphite compound represented by formula (3)

##STR00001##

(wherein R.sup.2 represents a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms; and X represents a hydrogen atom or a methyl group) in such an amount that more than 3 molecules hut not more than 15 molecules of the phosphite compound represented by formula (3) are present per one platinum atom in component (C). This one-pack type curable silicone gel composition is stable in terms of characteristics and physical properties even if exposed to a temperature more than 50° C. for a long period of time.

Reaction system for preparing acetoxy function-bearing siloxanes having chain lengths of more than 3 silicon atoms, comprising silanes and/or siloxanes bearing alkoxy groups, silanes and/or siloxanes bearing acetoxy groups, silanes and/or siloxanes bearing hydroxy groups and/or simple siloxane cycles and/or DT cycles, and also a reaction medium comprising acetic anhydride, Brønsted acid and acetic acid, wherein Brønsted acids having a pKa ≤−1.30 are used, and wherein the acetic acid is present in the reaction system in amounts of 0.4 to 15.0 percent by weight, based on the reaction system, wherein the molar ratio of Brønsted acid used to acetic acid is in a defined range, with the proviso that either the sole use of trifluoromethanesulfonic acid and also of trifluoromethanesulfonic acid and acetic acid is excluded, and/or that the Brønsted acid used at least in part has a pKa between −1.3 and >−13.5.

The present invention relates to a moisture-curable composition that is a compound containing a silane-terminated modified polymer as a main component, has both excellent workability due to low viscosity at a high shear rate and sufficiently high thixotropic properties due to high viscosity at a low shear rate, and during attachment of a heavy object such as a ceramic tile to a substantially vertical face of a construction or the like, can prevent sagging of the ceramic tile. The moisture-curable composition of the present invention is a moisture-curable composition prepared by adding (A) a polymer having a hydrophobic moiety and a hydrophilic moiety as a main component, (B) a diluent having a predetermined viscosity range, (C) hydrophobized inorganic particles, and (D) a thixotropic agent having a hydrophobic moiety and a hydrophilic moiety, whereby the composition exhibits performances of suppressing the viscosity at a high shear rate to a value equal to or lower than a certain value, and at the same time, increasing the viscosity at a low shear rate.

Silicone resin having the general formula

##STR00001##

where R.sup.1 are identical or independently different monovalent hydrocarbon radicals or —OH and R.sup.2 are identical or independently different monovalent organofunctional hydrocarbon radicals, olefinically unsaturated hydrocarbon radicals or a hydrogen radical. Where R.sup.2 is bonded to the silicon atom via a carbon atom and R.sup.2 is a hydrogen radical that is bonded to the silicon atom directly. Where c is 0 or 1, (Ic) present in not less than 5 mol %, (Ia) present in not less than 20 mol %, (Ib) present in not more than 20 mol %, (Id) present in not more than 20 mol %. Not less than 1 mol % of units (Ic) contain a radical R.sup.2 that is a hydrogen radical and not less than 1 mol % of (Ic) contain radicals R.sup.2 that is an olefinically unsaturated hydrocarbon radical and includes pulverulent and fibrous fillers.

The purpose of the present invention is to provide an addition-curable silicone rubber composition which gives a cured product having a controlled oil-bleeding property and releasability from a mold, without increasing an amount of a bleeding oil to be added. Thus, the present invention provides an addition-curable silicone rubber composition comprising the following components (A) to (D): (A) 100 parts by mass of an organopolysiloxane having at least two alkenyl groups each bonded to a silicon atom, (B) 0.2 to 20 parts by mass of an organohydrogenpolysiloxane having at least two hydrogen atoms each bonded to a silicon atom, (C) a catalytic amount of a platinum group metal catalyst, and (D) 1 to 10 parts by mass of a silicone oil represented by the following formula (1): ##STR00001##
wherein R.sup.1 is, independently of each other, an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, R.sup.2 is, independently of each other, a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, the amount of the monovalent aromatic hydrocarbon group is at least 35 mol % and less than 50 mol %, relative to a total amount of all substituents each bonded to a silicon atom, that is, all of R.sup.1 and R.sup.2, m is an integer of from 0 to 3, m′ is an integer of from 0 to 3, n′ is an integer of from 0 to 3, n is an integer of from 10 to 20, and m+m′+n+n′ is in a range of from 10 to 22.

A thermosetting resin composition and a prepreg and a metal foil-covered laminate made using same, the thermosetting resin composition comprising component (A): a solvent-soluble polyfunctional vinyl aromatic copolymer, the copolymer being a poly-functional vinyl aromatic copolymer having a stoctoal unit derived from monomers comprising divinyl aromatic compound (a) and ethyl vinyl aromatic compound (b); and component (B): a vinyl-containing organic silicone resin. The prepreg and metal foil-covered laminate made from the thermosetting resin composition have good toughness, and maintain a high glass transition temperature, a low water absorption, dielectric properties and humidity resistance, being suitable for the field of high-frequency and high-speed printed circuit boards and the processing of multilayer printed circuit boards.

A networked silicone is disclosed. The networked silicone comprises crosslinked strands of looped organosilicon compounds. A composition for preparing the networked silicone is also disclosed, and comprises (A) a looped organosilicon compound, (B) a crosslinking organosilicon compound, and optionally (C) a catalyst. Additionally, a method of preparing the networked silicone is disclosed, and comprises reacting the looped organosilicon compound (A) and the crosslinking organosilicon compound (B), optionally in the presence of the catalyst (C), to give the networked silicone. A reaction product comprising the networked silicone is also disclosed. The reaction product is prepared from the composition and/or in accordance with the method, and may be a cured product. Additionally, a composite article and a method of forming the same are disclosed. The composite article is formed by disposing a networked silicone composition on the substrate and curing the networked silicone composition, thereby preparing the composite article.

A reaction product containing a non-cyclic alkoxy-functional polysiloxane is produced by heating a reaction system, which contains a cyclic polyorganosiloxane of the formula [(R.sup.1.sub.2SiO).sub.2/2].sub.n, where the subscript n is an integer of at least 4 and each R.sup.1 is an alkyl group or aryl group; a silane of the formula R.sup.2.sub.(4−m)Si(OR.sup.3).sub.m, where the subscript m is an integer from 1 to 4, each R.sup.2 independently is an alkyl group or aryl group, a hydrocarbyl group or a halogenated hydrocarbyl group and each R.sup.3 independently is an alkyl group; and a catalyst system comprising a metal trifluoromethanesulfonate of the formula [M].sup.+[CF.sub.3SO.sub.3].sup.−, where M is a metal atom selected from sodium (Na) and potassium (K), and a Brønsted acid, wherein Brønsted acids having a pKa≤3.0, preferably having a pKa≤2.0, particularly preferably having a pKa≤−0.0 are used.

A polyorganosiloxanes has an anhydride functionality and an aromatic functionality, wherein a carbon of the aromatic functionality is separated from a carbon of a carbonyl group of the anhydride functionality by a carbon chain, wherein the polyorganosiloxane contains 5 weight-percent or more silicon atoms based on weight of the polyorganosiloxane.