Dow Corning Toray Silicone Company Limited

Tomoo Kinoshita

Mitsuo Hamada

Kaoru Kunimatsu

Hideyuki Mori

Teruyuki Nakagawa

Satoru Terashima

Junya Yokoi

A method for manufacturing of a silicone rubber base composition in a mass-like form, comprises:

Method for the continuous manufacturing of silicone rubber composition

A method for continuous preparation of a high consistency or liquid silicone rubber base does not cause abrasive wear of the extruder screw and of the extruder cylinder or blackening of the silicone rubber base even when the latter is admixed with such fillers as an inorganic filler in the form of a diatomaceous earth powder, quartz or a similar large-grained and hard substance, or with a fumed silica, sedimentary silica, or a similar reinforcing silica filler. The method comprises continuously kneading the following components in a multiple-stage shear type single-screw extruder: (A) a freely-flowable powdered silicone rubber mixture having its main components in the form of (a) a cross-linkable polydiorganosiloxane with a viscosity exceeding 1.times.10.sup.5 mPa.multidot.s at 25.degree. C. and (b) an inorganic filler, and (B) a high consistency silicone rubber base having its main components in the form of (a) a cross-linkable polydiorganosiloxane with a viscosity exceeding 1.times.10.sup.5 mPa.multidot.s at 25.degree. C. and (c) a reinforcing silica filler, or a liquid silicone rubber base having its main components in the form of (d) a cross-linkable polydiorganosiloxane with a viscosity below 1.times.10.sup.5 mPa.multidot.s at 25.degree. C. and (c) a reinforcing silica filler.

A highly productive, continuous method for the production of room-temperature-curable organopolysiloxane compositions is obtained by continuously feeding 100 parts by weight of a diorganopolysiloxane with a viscosity at 25.degree. C. of 0.1 to 500 Pa.s that contains at least 2 silicon-bonded hydroxyl groups or hydrolyzable groups in each molecule; 1 to 30 parts by weight of an organosilane that contains at least 2 silicon-bonded hydrolyzable groups in each molecule, or the partial hydrolysis condensate thereof; 1 to 200 parts by weight of an inorganic filler in powder form, and 0 to 10 parts by weight of a cure-accelerating catalyst into a continuous mixing apparatus having starting material feed openings installed at its top, a discharge opening installed at its bottom, and a rotating disk installed within a casing and are therein mixed by the rotation of the said rotating disk, and in that the resulting mixture is thereafter continuously introduced into a vacuum mechanism- equipped degassing apparatus in which the water fraction present in the said mixture is removed under reduced pressure.

Method for the continuous production of room-temperature-curable

The present invention relates to a method for the continuous preparation of heat-vulcanizing silicone rubber compounds. The method comprises continuous feeding of (A) 100 weight parts polydiorganosiloxane gum, (B) 5 to 100 weight parts reinforcing filler, and (C) up to 30 weight parts processing aid to a co-rotating twin-screw continuous compounding extruder. The components (A), (B), and (C) are continuously mixed in the extruder at a temperature in a range of about 200.degree. C. to 300.degree. C. The mixed components are then discharged, forming an extrudate. The extrudate is fed continuously to a counter-rotating twin-screw continuous compounding extruder, wherein the extrudate is continuously heat-treated at a temperature in a range of 150.degree. C. to 300.degree. C., forming the silicone rubber compound, which is then discharged from the counter-rotating twin-screw continuous compounding extruder.

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Fukui Prefecture, Japan

Tomoo Kinoshita