Dow Corning Toray Silicone Company Limited

Toray Dow Corning Silicone

Kaoru Kunimatsu

Mitsuo Hamada

Tomoo Kinoshita

Ryuji Tachibana

Asao Harashima

Atsushi Sasaki

Atsushi Komatsu

Teruyuki Nakagawa

Satoru Terashima

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.

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.

Method for the continuous preparation of heat-vulcanizing silicone

A method for producing powder mixtures capable of inducing an even more intimate, microhomogeneous intermixing in a heterogeneous powder composed of at least two types of powders. The method is effective even for the mixing of an aggregable powder and a nonaggregable powder. According to the method, a heterogeneous powder composed of at least two type of powders that have been preliminarily mixed by stirring is introduced into an inlet while a rotating axle is turning and is axially transported within a cylinder by a screw. As the heterogeneous powder passes between rotating disks and fixed disks, it is subjected to a highly efficient mixing by compression and shear forces due to a sliding-shear action exerted between depressions and elevations installed on the opposing surfaces of the rotating disks and fixed disks. The mixture passes in sequence through multiple stages of the rotating and fixed disks. A powder mixture, which has been microhomogeneously interdispersed, is discharged from the outlet.

Method for the preparation of powder mixtures

Curable fluororubber compositions comprising an organic fluororubber, an organopolysiloxane gum and an epoxy-containing organoalkoxysilane or partial hydrolyzate thereof, a reinforcing filler and an organoperoxide are characterized by excellent roll workability during roll milling and can be cured to yield a fluororubber which undergoes little deterioration in its mechanical properties at low temperatures.

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Fukui Prefecture, Japan

Kaoru Kunimatsu