Abstract: In a semiconductive silicone elastomer composition comprising an organopolysiloxane containing at least two aliphatic unsaturated hydrocarbon groups attached to a silicon atom, an organohydrogenpolysiloxane containing at least two hydrogen atoms attached to a silicon atom, and a conductive agent, the conductive agent consists of 1-10 wt % of conductive carbon and 99-90 wt % of a conductive filler having a volume resistivity of 10.sup.1 -10.sup.8 .OMEGA.-cm other than the conductive carbon. The conductive agent is blended in an amount of 20-60 wt % of the entire composition. The composition having the conductive agent uniformly dispersed therein yields a semiconductive silicone elastomer having a volume resistivity of 10.sup.5 -10.sup.10 .OMEGA.-cm with a dispersity of 1 to 10.

Abstract: A process for preparing a room temperature-curable organopolysiloxane composition comprising (A) (A-1) a specific organopolysiloxane or a mixture of (A-1) and (A-2) a specific silicone compound or a partial hydrolysis product thereof, (B) silica powder having a specific surface area of 20 to 800 m.sup.2 /g, (C) a curing catalyst, and (D) a silane coupling agent or an organopolysiloxane having a specific substituent, which comprises adding component (D) to component (A) prior to kneading or at the time of kneading components (A) and (B). The composition exhibits excellent physical characteristics, excellent workability in terms of flowability, adhesion, and extrudability, undergoes no change in viscosity with time and, in particular, suffers no impairment of these characteristics when stored for a long period of time.

Abstract: A silicone composition is formed as a system including: a silicone compound, reactive group-containing modified silicic acid powder of which surface has been modified with an alkylsilane, a hexamethyldisilazane, a dimethylsilicone oil, or a mixture thereof, and an unsaturated group-containing silane compound; and inorganic fine powder carrying a surfactant. The silicone compound is preferably an addition reaction-type silicone rubber prepared from a dimethyl polysiloxane having a vinyl group, a methylhydrogenpolysiloxane and a platinum-based catalyst. The silicone composition is heat-cured to provide an elastic revolution body which is suitably used to constitute one or both of a fixing roller and a mating pressure roller in a roller fixing device for electrophotography.

Abstract: The invention relates to a tire with a tread. The tread is composed of three basic elastomers, namely, medium cis 1,4-polybutadiene rubber, isoprene/butadiene copolymer and natural cis 1,4-polyisoprene rubber and which is reinforced with either carbon black or a combination of carbon black and silica reinforcing fillers.

Abstract: A process of making a polydiorganosiloxane-silica foundation mixture from a free-flowing, powdered, surface-modified, reinforcing silica-polydiorganosiloxane concentrate used to make, for example, RTV silicone sealant compositions which have non-sag properties. The foundation mixtures are made by combining, mixing, and heating a reinforcing silica filler and a surface modifying agent to a temperature of >90.degree. C. to <180.degree. C. using 0.1 to 0.5 parts by weight of the surface modifying agent per one part by weight of the silica. Polydiorganosiloxane is added gradually to the resulting fluidized filler over a time period of less than 10 minutes to obtain the free flowing powdered reinforcing silica-polydiorganosiloxane concentrate. The foundation mixture is obtained by massing the concentrate and adding more polydiorganosiloxane to obtain a mixture which has from 8 to 20 weight percent silica filler.

Abstract: A process of making a polydiorganosiloxane-silica foundation mixture from a free-flowing, powdered, surface-modified, reinforcing silica-polydiorganosiloxane concentrate used to make, for example, RTV silicone sealant compositions which have non-sag properties. The foundation mixtures are made by combining, mixing, and heating a reinforcing silica filler and a diol surface modifying agent to a temperature of 20.degree. C. to <180.degree. C. using 0.05 to 0.5 parts by weight of the diol per one part by weight of the silica. Polydiorganosiloxane is added gradually to the resulting fluidized filler over a time period of less than 10 minutes to obtain the free flowing powdered reinforcing silica-polydiorganosiloxane concentrate. The foundation mixture is obtained by massing the concentrate and adding more polydiorganosiloxane to obtain a mixture which has from 5 to 20 weight percent silica filler. The foundation mixtures have a plateau stress of >700 dynes/cm.sup.

Abstract: The invention relates to a water based binder for use in a slurry for investment casting. The binder includes a mixture of a colloidal silica sol and at least one latex polymer. The latex polymer is preferably an acrylic latex or a styrene butadiene polymer (or a combination of these) which reduces the processing time between dips during shell mold making for investment casting. The latex polymer further lowers a critical concentration point or gelation point of the colloidal silica sol. The binder may be used as a primary binder or a backup binder in the shell mold making process. To make the slurry, the binder is combined with at least one refractory powder, preferably a refractory powder selected from the group of: alumino-silicates, fused silica, quartz silica, alumina, zircon, and zirconia.

Abstract: A copolyester composition comprising poly(ethylene naphthalate bibenzoate) ("PENBB") and 0.001 to 5% by weight of fine silica particles having an average diameter of 0.01 to 3.0 .mu.m. Further, films are made from this copolyester composition.

Abstract: Liquid polysiloxanes are used in defoamant preparations, as diffusion-resistant plasticizer oils, separation agents, or impregnation agents. The liquid polysiloxanes are obtained by reacting:(1) 100 parts by weight of the hydrolysis product of dimethyldichlorosilane having a viscosity of less than 200 mm.sup.2 /sec at 25.degree. C.;(2) 1-100 parts by weight of a polydiorganosiloxane having a viscosity of less than 200 mm.sup.2 /sec at 25.degree. C., of formula (I)R.sup.3.sub.c SiO.sub.(4-c)/2, (I)where each R.sup.3 is independently a substituted or unsubstituted hydrocarbon group with 1-30 carbon atoms, and c has mean value 1.9-3.0; and(3) 0.1-20 parts by weight of one or more compounds (a)-(d),where (a) is a silicon compound of formula (II)R.sup.4.sub.d SiX.sub.(4-d), (II)where R.sup.

Abstract: A crosslinked polysiloxane dispersion comprising a product of a siloxane polymer or polymer mixture having a viscosity of greater than 5000 mPa.s but less than 500,000 mPa.s, and at least one self catalyzing crosslinker, a surfactant, and water.

Abstract: A process of making a pumpable, stable, polydiorganosiloxane-silica foundation mixture by mixing and heating a polydiorganosiloxane, a reinforcing silica filler, and a diol surface modifying agent at >50.degree. C. to <180.degree. C. using 0.05 to 0.5 parts by weight of the diol per one part by weight of the silica. The foundation mixture can be used to make RTV silicone sealant compositions which are non-sag.

Abstract: The present invention relates to organopolysiloxane-containing compositions which are self-dispersing in water, their preparation and their use. The compositions of the present invention are suitable for all uses where organosilicon compounds, especially in water-diluted form, can be employed. Such uses include uses as water repellant agents on building materials.

Abstract: An optically clear platinum-group metal curable liquid silicone rubber composition having good physical properties. The composition comprises a vinyldimethylsiloxy-terminated polydimethyl(diphenyl)siloxane copolymer comprising about 1 to 20 mole percent diphenylsiloxy units and having a viscosity within a range of about 20,000 mPa.multidot.s to 100,000 mPa.multidot.s at 25.degree. C., vinyldimethylsiloxy-terminated polydimethyl(diphenyl)siloxane copolymer comprising about 1 to 20 mole percent diphenylsiloxy units and having a viscosity within a range of about 50 mPa.multidot.s to 10,000 mPa.multidot.s at 25.degree. C. and optionally comprising up to about 3 mole percent vinyldimethylsiloxy units, a treated reinforcing silica filler, and curing agents.

Abstract: The invention relates to organopolysiloxane compositions that when crosslinked form electroconductive elastomers. The elastomers are formed via an addition crosslinking method and contain 11% to 30% by weight with respect to the total composition of carbon fibers having a 0.1 to 10 mm average length. The compositions are suitable for producing injection molded articles.

Abstract: A composition useful as a casting resin is provided. The composition comprises a polyol, a polyisocyanate, a catalyst, and a suspension aid, and said catalyst and said suspension aid are present in the casting resin in such concentrations that, within 10 minutes of mixing, it flows downwards a) by at least 15 cm at 25.degree. C. and b) by 3 to 0.3 cm at 130.degree. C. The casting resin is particularly useful as a binder for a granular material in the production of open-cell moldings which are permeable to water.

Abstract: An addition reaction-type dimethylsilicone composition, including a diorganopolysiloxane containing a reactive vinyl group; an organopolysiloxane containing an active hydrogen atom; and silicic acid fine powder of which surface has been treated with a fluoroalkylsilane, an alkylsilane compound, a fluorosilicone oil, a dimethylsilicone oil, or a mixture thereof, and a silane compound containing an unsaturated group having a reactivity to the organopolysiloxane containing an active hydrogen atom.

Abstract: Cold processable heat curable alkenyl silicone rubbers that comprising an alkenyl silicone gum or mixture of alkenyl silicone gums selected from the group of alkenyl silicone gums having the formula:(M.sub.a M.sup.vi.sub.1-a)(D.sup.vi).sub.x (D).sub.y (M.sub.a M.sup.vi.sub.1-a);a process for making such heat curable rubbers, and articles of manufacture made therefrom.

Abstract: A thermoplastic polyurethane elastomeric seal composition comprising, by weight, about 90% to 99% thermoplastic polyurethane elastomer and about 1% to 10% fibers. Also, the thermoplastic polyurethane elastomer is derived from the reactants comprising: (i) a mixture of polyol and an aromatic chain extender in a molar ratio in the range of from about 40:60 to about 60:40 of butanediol glycol adipate to hydroquinone bis 2-hydroxyethyl ether, and (ii) 1,5 naphthalene diisocyanate present in a molar ratio in the range of about 50:50 to about 54.5:45.5 of 1,5 naphthalene diisocyanate to the said first mixture of polyol and an aromatic chain extender. After curing, the thermoplastic polyurethane elastomeric seal compound has outstanding wear resistance and low compression set.This thermoplastic polyurethane elastomeric seal compound is particularly useful in making shaft seals subject to high wear and high pressure, for use in hydraulic rams in earthmoving equipment.

Abstract: A silicone rubber composition comprising an organopolysiloxane and a reinforcing silica filler can be improved in crepe hardening and shelf stability by blending a specific compound as a wetter.

Abstract: A hardenable composition suitable for flooring and for coating concrete surfaces comprising(a) an acrylic binder comprising a (meth)acrylic ester of the formula ##STR1## where R.sub.1 is C.sub.2-6 alkylene, n is 0-3 and R.sub.2 is a radical of an aromatic or alicyclic dicarboxylic acid ester or a dicyclopentenyl radical, n being 0 only when R.sub.2 is a dicyclopentenyl radical, and(b) a component which is one or both (preferably both) of carbon black and a polyfunctional aliphatic or aromatic polyester- or polyether- urethane oligomer. The composition also preferably comprises aggregate such as sand. The compositions have excellent impact resistance and flexural strength.

Abstract: A method for making a fluorinated polydiorganosiloxane base composition and the composition prepared thereby. The base composition can be addition cured using a platinum-metal group catalyst and an organohydrogensiloxane crosslinker to form a fluorosilicone elastomer having improved resiliency and compression set properties.

Abstract: A composition curable to a silicone elastomer is prepared by mixing a triorganosiloxy endblocked polydimethylsiloxane fluid where the triorganosiloxy is dimethylvinylsiloxy or methylphenylvinylsiloxy, a reinforcing silica having a surface treated with organosiloxane groups which contain 0.05 to 0.32 percent by weight vinyl, a hydroxy end-terminated polydiethylsiloxane fluid, an organohydrogensiloxane fluid, a platinum catalyst, and optionally a platinum catalyst inhibitor. The triorganosiloxy endblocked polydimethylsiloxane fluid has a major peak molecular weight of 68,000 to 135,000, a dispersity index greater than 3.8, the lowest molecular weight species between 854 and 3146 and the highest molecular weight species between 174,000 and 370,000. These compositions are readily extrudable under low pressure, have improved pot-life, cure to high strength elastomers with a high durometer, and have improved mold release.

Abstract: The silicone rubber composition of the present invention comprises (A) an organopolysiloxane obtained by mixing and heating an organopolysiloxane having a silanol group at both ends of the molecular chain and a silane or a siloxane having two hydrolyzable groups in the molecule, (B) a finely divided silica, and (C) a curing agent. The composition, wherein the content of low-molecule siloxanes is remarkably constrained, is quite useful in the application wherein low-molecular siloxanes are obnoxious, for example, in the application of electrical contacts and parts used adjacent thereto, roll materials of copying machines, gaskets for construction, etc.

Abstract: The tendency for hard and irregular particles of titanium dioxide pigment to adversely affect the sheen and coin mar resistance of a dried coating into which they have been incorporated is reduced by modifying the particles with polymer particles which have been preformed and are therefore of a more pre-determinable shape and size. The polymer particles are chemically bonded to a polymeric water-soluble compound containing moieties which are adsorbable onto the titanium dioxide particles so that on mixing a colloidally stabilised aqueous dispersion of the polymer particles with a colloidally stabilised aqueous dispersion of titanium dioxide particles, the moieties adsorb onto the titanium dioxide to form a colloidally stable aqueous dispersion of polymer-modified titanium dioxide which is useful in coating compositions.

Abstract: A silicone gel composition comprising (A) a linear organopolysiloxane having a backbone consisting only of trifluoropropyl-substituted siloxane units and terminated with alkenyl group, (B) an organohydrogenpolysiloxane, (C) a platinum catalyst, and (D) a finely powdered silica whose surfaces have been rendered hydrophobic by treatment with a silicon compound having only methyl groups as substituent groups, such as hexamethyldisilazane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane and cyclic or linear dimethylpolysiloxanes. The composition has good thixotropy and can effectively provide a protective layer by spot potting. The silicone gel formed from the composition is excellent in solvent resistance, etc. and is effectively restrained from shrinkage or the like. Therefore the composition is highly suited to use as a protective material for semiconductor-type pressure sensors.

Abstract: Disclosed is a water-dissipatable alkyd resin containing a sulfonate group. The alkyd resin is prepared by reacting at least one monoglyceride, a polycarboxylic acid, and a polyol sulfomonomer adduct containing at least one sulfonate group. The alkyd resin is useful to prepare cross-linked coatings such as obtained with oil based paints.

Abstract: A curable silicone rubber composition contains (A) an organopolysiloxane raw rubber containing 0.01-1% by weight of vinyl and having a viscosity of 10.sup.3 -10.sup.6 poise at 25.degree. C., (B) an organopolysiloxane oil containing 0.1-10% by weight of vinyl and having a viscosity of 0.05-100 poise at 25.degree. C., (C) an organopolysiloxane copolymer composed mainly of a triorganosiloxy unit (M) and SiO.sub.2 unit (Q) in a molar ratio (M/Q) between 0.6 and 1.2 and containing 0.1-10% by weight of vinyl, (D) an organohydrogensiloxane containing at least three silylidyne groups, (E) a platinum catalyst, and (F) finely divided silica as essential components. The composition is hot air vulcanizable into a silicone rubber which is improved in hardness, modulus, tear strength and compression set.

Abstract: There are disclosed carbonate polymers of dihydroxyaryl fluorene having crosslinkable moieties. There are also disclosed such polymers in the form of composites. The polymers of this invention are capable of being crosslinked by activation of the crosslinkable moieties. Once crosslinked, these polymers demonstrate an excellent combination of properties including resistance to melting at high temperatures, solvent resistance, optical clarity, impact resistance, and physical strength.

Abstract: A method for continuously producing a room temperature vulcanizable composition is disclosed. A base mixture of a silanol stopped fluorosilicone polymer, a silica filler and iron oxide are processed in an extruder at an elevated temperature between about 50.degree. and 200.degree. C. Thereafter, a tin based catalyst, an acetoxy cross-linking agent and an optional adhesion promoter are added to the extruder near the exit port. The resulting material has improved storage stability.

Abstract: A process for preparing a liquid silicone rubber base composition of the type which comprises (A) an organopolysiloxane of the following average compositional formula (1)R.sub.a SiO.sub.(4-a)/2 (1)wherein each R independently represents an unsubstituted or substituted monovalent hydrocarbon group and a is a value of from 1.95 to 2.05, and (B) a finely divided silica filler is described. The process comprises the steps of mixing a first portion of the ingredient (A) and the ingredient (B) at a temperature not higher than 80.degree. C., further mixing a second portion of the ingredient (A) with the mixture obtained in the first step at a temperature not higher than 80.degree. C. and subjecting the resultant mixture to thermal treatment at a temperature of 130.degree. to 200.degree. C. By this, the base composition has good fluidity and is able to yield a cured product having good tear strength under stress.

Abstract: Crosslinkable liquid composition based on organic isocyanates and epoxy compounds, comprising the following components:(A) an organic polyisocyanate;(B) a polyepoxide or mixture of a polyepoxide and a monoepoxide; and(C) a catalyst constituted by at least one cyanoderivative containing a quaternary nitrogen atom,which composition can be polymerized at temperatures of 40.degree. C. or higher, by a process comprising exposure thereof to a non-ionizing electromagnetic radiation having a frequency comprised in the microwave range of frequencies, to obtain a solid material endowed with an excellent combination of physical, chemical and mechanical properties.

Abstract: A frosting agent in which particulate silica suspends with high dispersibility without lowering the flow-out and formability of an aqueous polyurethane as a binder of frosting coating agent. Such a frosting agent for use in an aqueous polyurethane is obtained by adding 0.5-5.0 parts by weight of .gamma.-ureidopropyltriethoxysilane and 0.1 part by weight or more of water to 100 parts by weight of particulate silica and reacting said substances at a temperature of 15.degree.-100.degree. C. to modify the surface of said particulate silica. By this reaction, .gamma.-ureidopropylsilane liberated by hydrolysis of ethoxysilane groups reacts with acid hydroxy groups. Thus, the wettability and compatibility of the frosting agent with respect to aqueous polyurethane increases. This improves the dispersibility and the resistance to scuff of the coating.

Abstract: A conductive silicone rubber composition is prepared by mixing an organopolysiloxane having an aminoalkyl radical, an organopolysiloxane having a (meth)acryloxyalkyl or glycidoxyalkyl radical, and conductive carbon black to form silicone rubber composition (A) in which the carbon black is fixed, and then mixing it with a silicone rubber composition (B) comprising a dimethylpolysiloxane. The composition has stable resistivity in the semiconductive region independent of molding conditions.

Abstract: A conductive silicone rubber composition comprising (A) an organopolysiloxane, (B) conductive carbon black, and (C) an organic peroxide is improved in shelf stability by adding (D) a fatty acid or an acid anhydride thereto. The composition is subject to atmospheric hot air vulcanization to form a conductive silicone rubber having improved conductivity and physical properties.

Abstract: A room temperature curable polyorganosiloxane composition according to the present invention, which comprises the following components, is superior in handleability and affords a cured product superior in mechanical characteristics, particularly tear strength:1 100 parts by weight of a polyorganosiloxane having at least two silanol groups in one molecule;2 1-25 parts by weight of an organosilane or organosiloxane having in one molecule at least three hydrolyzable groups attached to silicon atom;3 0.01-10 parts by weight of a curing catalyst; and4 5-500 parts by weight of ultra-fine titanium oxide particles.

Abstract: A surface coating composition comprising, in combination, a fibrillated polymer matrix, at least one pigment, at least one binder, and at least one solvent, and a method for the manufacture thereof.

Abstract: The tendency for hard and irregular particles of titanium dioxide pigment to adversely affect the sheen and coin mar resistance of a dried coating into which they have been incorporated is reduced by modifying the particles with polymer particles which have been preformed and are therefore of a more pre-determinable shape and size. The polymer particles are chemically bonded to a polymeric water-soluble compound containing moieties which are adsorbable onto the titanium dioxide particles so that on mixing a colloidally stabilised aqueous dispersion of the polymer particles with a colloidally stabilised aqueous dispersion of titanium dioxide particles, the moieties adsorb onto the titanium dioxide to form a colloidally stable aqueous dispersion of polymer-modified titanium dioxide which is useful in coating compositions.

Abstract: An exothermic conductive coating comprises carbon particles, a substantial portion being spherical particles having a diameter of not more than 500 .mu.m, and a synthetic resin. A conductive heating unit is obtained by coating or impregnating a desirably-shaped solid or solid surface with the coating and curing it. The heating unit provides a uniform temperature distribution at any selected temperature up to about 450.degree. C., and can be formed in various shapes.

Abstract: A hardenable monomer composition useful for flooring composition, grouts, mortars and the like comprises a mixture of crosslinkable acrylic monomer, carbon black and/or polyester- or polyether-methane oligomer having at least two polymerizable double bonds and a paraffin oil.The monomer is preferably of the formula I ##STR1## and there is preferably present other monomers, particularly hydroxypropyl methacrylate.

Abstract: A toner composition is produced by bulk- or solution-polymerizing a fixer resin in the presence of toner-characteristic imparting agents such as a colorant and a charge controlling agent. According to this process, unlike a suspension polymerization method, since no surface-active agent is used at any stage of production, the produced toner is remarkably proof against moisture. Especially, if a grafted carbon black is used as the colorant, it is possible to obtain a toner in which the colorant is dispersed minutely and uniformly throughout the fixer resin.

Abstract: A white blackout fiber comprising a unitary fiber having a light blocking substance that substantially prevents the transmission of light therethrough and a whitening agent, where the whitening agent is present in an amount which provides for good after processing while the light blocking substance is present in the maximum amount which is masked by the whitening agent. Generally, the whitening agent is present in an amount between about 2.5-4% by weight of the fiber, and the whitening agent and light blocking substance are present in a ratio of between about 1000:1 and 800:1. Preferably, the whitening agent is TiO.sub.2 and the light blocking substance is carbon black.

Abstract: An addition-curable type silicone rubber composition comprising (A) an organopolysiloxane having an alkenyl group such as vinyl in its molecule, (B) an organohydrogenpolysiloxane having at least two SiH groups in its molecule, (C) a platinum catalyst such as platinum, chloroplatinic acid, etc., (D) an inorganic filler, (E) an organic titanium compound such as tetraethyl titanate, and (F) water. The composition exhibits good fluidity, and behaves like a Newtonian fluid, even where carbon black or a silica or alumina having an average particle diameter of 1 .mu.m or above is incorporated in the composition as an inorganic filler for improving such characteristics as heat resistance, thermal conductivity, etc.

Abstract: The invention relates to optically active, pressurestable bead polymers containing fillers, and their use as adsorbents for the chromatographic resolution of enantiomeric mixtures (or racemates) into their enantiomers.

Abstract: A process for producing nylon-4,6 which is filled with a reinforcing agent by mixing a reinforcing agent with nylon-4,6 in the melt comprises the steps ofa) polycondensing a salt of 1,4-diaminobutane and adipic acid in the presence of excess 1,4-diaminobutane and water at polyamide-forming temperatures under superatmospheric pressure to give a precondensate having a relative viscosity .ltoreq.1.60,b) polycondensing the precondensate of a) in solid phase in the presence of steam at 220.degree.-270.degree. C. to obtain a nylon-4,6 having a relative viscosity of from 2.0 to 2.6,c) incorporating a reinforcing agent in the melt into nylon-4,6 from stage b) to obtain a nylon-4,6 filled with a reinforcing agent,d) polycondensing said filled nylon-4,6 in solid phase in the presence of steam at 220.degree.-270.degree. C. to a relative viscosity of at least 3.2.

Abstract: This invention provides polymerizable silica sols in which at least one monomer containing double bond is used as its dispersion medium, especially a silica sol in which the monomer containing double bond is a monomer containing double bond and OH group or is a monomer having an adamantane structure. This invention also provides compositions which comprise these silica sols as composing elements, cured resins that are obtained by polymerizing these silica sols alone or together with other copolymerizable components, and new adamantane derivatives for use in these silica sols.

Abstract: A coating composition that can be applied to optical plastic moldings having a high refractive index, to protect them from deterioration by light without any adverse effect on their optical functions. The coating composition contains the following essential constituents.(A) 1 part of a hydrolyzate of a silane compound;(B) 0.2-5 parts of titanium oxide-based composite fine particles having a particle diameter of 1-100 nm in which titanium oxide integrally combines with iron oxide, with the ratio of iron oxide to titanium oxide being 0.005-0.15 by weight;(C) 0.02-0.5 part of an unsaturated or saturated polycarboxylic acid or an anhydride thereof; and(D) 0.01-0.2 part of a heat-curing catalyst.

Abstract: Mixtures of polyisocyanates and epoxides are cured by microwave irradiation, optionally with microwave or thermal post-curing to produce cured polymer articles having good chemical, electrical and mechanical properties.

Abstract: The present invention provides a heat-curable silicone rubber composition to be cured by hydrosilation reactions and having outstanding physical properties, especially a high tear strength, said composition comprising(A) a polydiorganosiloxane having at least two unsaturated aliphatic hydrocarbon groups and represented by the general formula (1):R.sub.a.sup.1 SiO.sub.(4-a)/2 ( 1)wherein R.sup.1 represents a substituted or unsubstituted monovalent hydrocarbon group containing 0.01 to 15 mole % of an unsaturated aliphatic hydrocarbon group, a is a positive number of from 1.95 to 2.05.(B) a polyorganohydrogensiloxane having at least three hydrogen atoms directly bonded to silicon atom in a molecule,(C) silica filler having a specific surface area of at least 50 m.sup.2 /g, and(D) an addition reaction catalyst,(E) water, and preferably(F) an organosilane represented by the general formula:R.sub.m.sup.2 Si(OR).sub.4-mwherein R.sup.

Abstract: A silicone rubber composition comprising (A) an alkenyl-containing organopolysiloxane, (B) a polycyclic aromatic compound having at least two phenyl groups, and (C) finely divided silica is easy to process and cures to silicone rubber having low hardness while retaining good physical properties.

Abstract: A room temperature-curable organopolysiloxane composition which does not suffer from surface fissuring even when subjected to external stress (e.g., tensile stress, flexural stress) during the course of its cure was prepared and has a composition of a hydroxyl-terminated polydiorganosiloxane, a hydrophobic silica with a silanol titer not exceeding 2.0 mL, a dry-method silica with a silanol titer of at least 5.0 mL, and an oxime group-containing silane or siloxane.