Adhesive for silicone rubber

Abstract

An adhesive comprising (A) an organopolysiloxane containing, on average, at least two silicon-bonded alkenyl groups in a molecule, (B) an organohydrogenpolysiloxane containing, on average, at least two SiH groups in a molecule, (C) a calcium carbonate powder surface treated with a paraffinic compound and having a specific surface area of up to 6 m2/g, and (D) a platinum group metal catalyst is fully adherent to silicone rubber and shelf stable.

Description

Claims

1. An adhesive for silicone rubber comprising (A) 100 parts by weight of an organopolysiloxane containing, on average, at least two silicon-bonded alkenyl groups in a molecule and having a viscosity of 0.05 to 1,000 Pa-s at 23° C.,(B) an organohydrogenpolysiloxane containing, on average, at least two silicon-bonded hydrogen atoms in a molecule and having a viscosity of 0.001 to 100 Pa-s at 23° C., in such an amount that the molar ratio of silicon-bonded hydrogen atoms in component (B) to alkenyl groups in component (A) is from 0.01 to 20,(C) 1 to 100 parts by weight of a calcium carbonate powder surface treated with a paraffinic compound and having a specific surface area of up to 6 m2/g, as measured by the air-permeability method, and(D) an effective amount of a platinum group metal catalyst.

2. The adhesive of claim 1, wherein the calcium carbonate powder (C) is a heavy calcium carbonate powder having a specific surface area of up to 6 m2/g, as measured by the air-permeability method.

3. The adhesive of claim 1, further comprising (E) 1 to 100 parts by weight of a finely divided silica having a specific surface area of at least 50 m2/g, as measured by the nitrogen adsorption method.

4. The adhesive of claim 3, wherein components (A) and (E) are previously heat mixed.

5. The adhesive of claim 1, further comprising a tackifier.

6. The adhesive of claim 1, for use with a silicone rubber obtained by curing an addition cure type silicone rubber composition.