Toray Silicone Company Limited

Dow Corning Toray Silicone Company Limited

Dow Corning Toray Silicone

Koji Shimizu

Mitsuo Hamada

Keiji Yoshida

Haruki Wakita

Atsushi Sakuma

Masayuki Saito

Takao Matsushita

Toyohiko Yamadera

Katsuyoshi Nakasuji

Toshio Watanabe

A hydrophobic silica is prepared by mixing and heating a mixture of (a) 100 weight parts wet-method silica and (b) 1 to 100 weight parts organopolysiloxane represented by the following average unit formula R.sup.1.sub.a R.sup.2.sub.b SiO.sub.(4-a-b)/2, wherein R.sup.1 is a monovalent hydrocarbon group, R.sup.2 is the hydrogen atom, a is from 1 to 3 inclusive, and b is from zero to 1 inclusive, with the provisos that a+b is from 1.90 to 2.10 inclusive and b/(a+b) is from zero to 0.45 inclusive. This hydrophobic silica is used to prepare a high-strength silicone rubber particulate by mixing with a curable dioranopolysiloxane and curing the mixture in the form of particulates. A preferred manner of making the particulates is by emulsifying the mixture of hydrophobic silica and curable diorganopolysiloxane in water, then spraying the emulsion into a hot gas to cure the silicone rubber composition and remove the water, giving microparticles of high-strength silicone rubber.

High-strength silicone rubber particulate

A method is disclosed for preparing a heterogeneous silicone rubber molding wherein a portion of the molding is formed from a semicured silicone rubber particulate and a portion from a thermosetting silicone rubber composition. The mold is filled with the particulate and the thermosetting silicone rubber composition, then closed and pressurized and heated, forming the portions into a single body or element by curing the thermosetting silicone rubber composition at the same time that curing of the semicured silicone rubber particulate is brought to completion.

Method for the preparation of heterogeneous silicone rubber moldings

A method for the manufacture of silicone rubber moldings comprises the preparation of a silicone rubber composition by blending an organoperoxide having an activation energy of 25 to 41 kcal/mol into a semicurable organopolysiloxane composition whose main component is organopolysiloxane having organoperoxide-crosslinkable functional groups. The silicone rubber composition is made into a particulate form and heated at a temperature below 100 degrees Centigrade to produce a semicured, particulate molding material which retains the activity of the organoperoxide and which contains residual crosslinkable functional group on the organopolysiloxane. Subsequently a mold is filled with the molding material and the mold material is completely cured at a temperature of at least 100 degrees Centigrade under the application of pressure. The method is particularly useful for automatic molding methods.

Method of manufacturing silicone rubber moldings

Silicone gel spherical particles are prepared by continuously discharging a silicone gel composition into water while continuously moving the discharge nozzle location with respect to the surface of the water.

Method for the preparation of silicone gel spheres

A method of producing a conductive silicone rubber particulate is disclosed in which the particulate is from 0.1 to 100 micrometers average diameter and is coated on the surface with carbon black. The method prepares an aqueous dispersion of silicone rubber composition particulate, carbon black, surfactant, and water, then removes the water.

Method of preparing a conductive silicone rubber particulate

One-part organosiloxane composition curable by a platinum-catalyzed hydrosilation reaction contain the catalyst encapsulated within finely divided particles of a cured silicone rubber. The compositions are storage-stable for up to several days at room temperature, yet cure relatively rapidly when heated.

Thermosetting organopolysiloxane composition

A method and apparatus is provided for the preparation of liquid dispersions comprising the uniform dispersion of a viscous liquid formed of strands, threads or columns, such as a silicone polymer in water.

Method and apparatus for the preparation of a water based dispersion of

This invention provides cured silicone rubber or gel particles exhibiting an average size of from 0.1 to 20,000 micrometers and containing from 0.5 to 70 weight percent, based on the weight of the particle, of entrapped mineral oil. When the particles are incorporated into a liquid or solid matrix material the oil is released from the particles into the matrix at a controlled rate and serves as a lubricating agent.

Silicone rubber or gel particles containing mineral oil

A method of making a tack-free silicone gel molding comprises the steps of molding a cross-linked organopolysiloxane into a gel having a tacky surface and a partial three-dimensional network structure which exhibits limited fluidity and deformation upon the application of stress; and coating the tacky gel with cured silicone rubber particles having an average diamter less than about 1 mm. The coating sep may optionally use an aqueous dispersion of the silicone rubber particles, which is then followed by a drying step to obtain a tack-free gel which is also shape-retaining.

Method of making tack-free silicone gel moldings

Tack-free silicone gel moldings and methods of making such moldings are prepared by coating tacky silicone gel moldings with a silicone rubber particles, having an average diameter less than about 1 mm.

Tack-free silicone gel moldings

The electroconductive silicon rubber particulate of the present invention is an electroconductive silicone rubber particulate characterized by the fact that it contains an electroconductive material and that the particle diameter is from 0.1 to 1000 micrometers. It is an electroconductive material having excellent properties of lubrication, and has the characteristic capability, when added to a variety of materials such as various organic resins and rubbers including silicone rubber, of contributing to these materials stable levels of conductivity ranging from the semiconductive range to the conductive range, for the prevention of electrostatic and electrical charge build-up.

Electroconductive silicone rubber particles

The finely divided cured silicone rubber particles of the present invention contain at least epoxide compound or a condensation product thereof. The epoxide compound or a condensation product thereof can be present in the free state or chemically bonded to the silicone rubber, and the particles have a particle diameter of 1 mm or less. The particles exhibit excellent compatibility with a variety of materials, including various organic resins and synthetic rubbers, and when added to or admixed with these materials enhance the physical properties of these materials and are durably bonded within matrices of these materials.

Finely divided silicone rubber additive material and method for

Spherical gel particles with elastomeric surfaces are made by dripping a liquid silicone gel composition containing alkenyl-containing organopolysiloxane, organohydrogenpolysiloxane, and a platinum catalyst into water or surfactant-containing water, curing and then contacting the surface of the silicone gel particles to organohydrogenpolysiloxane and curing to provide the elastomeric surface. The liquid silicone gel composition can also be extruded in fiber form into the water or surfactant-containing water with stirring to form the spherical particles which are cured and then the surface is contacted with organohydrogenpolysiloxane forming the silicone gel particles with elastomer surface. Alternatively, the liuqid silicone gel composition can be dripped or extruded in fiber form into a liquid having organohydrogenpolysiloxane to form the silicone gel particles with elastomer surface when the particles are cured. These spherical silicone gel particles are uniform and can be used to modify organic resins and be used for vibration absorption.

Method for the production of spherical silicone gel particles

Extruded articles such as filaments and films are fabricated by blending the components of a curable liquid silicone rubber composition at temperatures of from -60.degree. to +5.degree. C. and then extruding the composition into water maintained at a temperature of at least +25.degree. C. to cure said composition. The water bath preferably contains a surfactant to facilitate processing of the extruded article. The present method provides uniformly cured articles that are almost bubble-free and have low shrinkage ratios.

Process for molding silicone rubber compositions

The present invention provides a method for producing silicone rubber moldings composed of a uniform, smooth and hard exterior layer and a relatively soft interior portion. In accordance with this method the surfaces of the mold cavity are coated with an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms before the curable organosiloxane used to form the interior portion of the molding is injected into the mold cavity and cured.

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Chiba, Japan

Koji Shimizu