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Electrically conductive liquid silicone rubber composition

Imported: 23 Feb '17 | Published: 22 Oct '02

Syuuichi Azechi, Tsutomu Nakamura, Motoo Fukushima

USPTO - Utility Patents

Abstract

An electrically conductive liquid silicone rubber composition having (A) 100 parts by weight of an organopolysiloxane having a viscosity of 10-100,000 centipoise at 25° C., (B) 1-100 parts by weight of a finely divided silica powder, (C) 30-700 parts by weight of a metal powder or an electrically conductive metal-plated powder, and (D) a curing agent in an amount sufficient to cure the organopolysiloxane. The composition has a low volumetric resistivity, a stable electrical resistance and can be injection-molded and cured to give an outstanding silicone rubber that is useful in electrical components and electrical contacts employed in high-conductivity applications.

Claims

1. An electrically conductive liquid silicone rubber composition comprising:

2. The conductive liquid silicone rubber composition of claim 1, wherein component A is at least one organopolysiloxane of the following average constitutional formula (1):

R

1

aSiO

(4-a)/2  (1),

wherein R

1 is a substituted or unsubstituted monovalent hydrocarbon group of 1 to 12 carbons, from 0.001 to 20 mol % of the R

1 groups being alkenyl groups, and the letter a is a positive number from 1.5 to 2.8;

3. The silicone rubber composition of claim 1, wherein component C is a metal-plated silica powder having a construction comprising silica covered with a nickel layer which in turn is covered with a gold layer.

4. The silicone rubber composition of claim 1, wherein the curing agent D is an organic peroxide.

5. The silicone rubber composition of claim 1, wherein the curing agent D is an addition reaction-type curing agent.

6. The silicone rubber composition of claim 1 which is injection moldable.

7. The silicone rubber composition of claim 1, wherein more than one type of said organopolysilixane A is used, wherein said organopolysiloxanes are capped at both ends of the molecular chain with trivinylsilyl, divinylmethylsilyl or vinyldimethylsilyl groups.

8. The silicone rubber composition of claim 2, wherein said a of the organopolysiloxane of formula (1) is a positive number from 1.8 to 2.5.

9. The silicone rubber composition of claim 2, wherein said organopolysiloxane of formula (1) is a linear diorganopolysiloxane also having R

1SiO

3/2 units and SiO

4/2 units.

10. The silicone rubber composition of claim 1, wherein said viscosity of the organopolysiloxane A is 50 to 50,000 centipoise.

11. The silicone rubber composition of claim 1, wherein said finely divided silica powder B is at least a precipitated silica, fumed silica, or fired silica, wherein any of said silica has a specific surface area of 50 to 400 m

2/g.

12. The silicone rubber composition of claim 1, wherein said finely divided silica powder B is incorporated in the amount of 2 to 50 parts by weight per 100 parts by weight of said organopolysiloxane A.

13. The silicone rubber composition of claim 1, wherein the average particle size of said electrically conductive metal-plated silica powder C is 0.05 to 100 m.

14. The silicone rubber composition of claim 1 or 3, wherein said silicone rubber composition comprising a four-layer construction of silica/silicon compound/nickel/gold, wherein said silicon compound is between the silica and nickel.

15. The silicone rubber composition of claim 3, wherein said organopolysiloxane A is dimethylpolysiloxane.