Emulsion composition for silicone rubber, process for producing the same, and process for producing silicone rubber

1. A method for preparation of an emulsion composition for manufacturing a silicone rubber, the emulsion composition comprising:

(A) 100 parts by weight of a diorganopolysiloxane having at least two silicon-bonded alkenyl groups in a molecule;

(B) 10 to 250 parts by weight of water that contains a smectite clay;

(C) 0.1 to 15 parts by weight of an emulsifier;

(D) (d1) a cross-linking agent in an amount sufficient for cross-linking component (A), and

(d2) a catalyst; and

(E) 0 to 60 parts by weight of a reinforcing silica filler, said method comprising the steps of loading a mixture of an appropriate amount of component (A) and an appropriate amount of component (E) together with an appropriate amounts of components (B) and (C) into a high-speed stiffer-equipped mixer, mixing the components till a uniform emulsion is formed, loading into the mixer an appropriate amount of components (d1) and (d2), and stirring and mixing the components.

2. The method according to claim 1 , wherein the smectite clay is a synthetic saponite.

3. The method according to claim 1 , wherein the component (B) contains the smectite clay in the amount of 1 to 10 parts by weight per 100 parts by weight of the water.

4. The method according to claim 1 , wherein the emulsifier of component (C) comprises a non-ionic surface-active agent.

5. The method according to claim 1 , wherein component (d1) is an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, and wherein component (d2) is a platinum-type catalyst.

6. The method according to claim 1 , wherein component (E) is a hydrophobically surface-treated reinforcing silica filler.

7. A method for preparation of an emulsion composition for manufacturing a silicone rubber, the emulsion composition comprising:

(A) 100 parts by weight of a diorganopolysiloxane having at least two silicon-bonded alkenyl groups in a molecule;

(B) 10 to 250 parts by weight of water that contains a smectite clay;

(C) 0.1 to 15 parts by weight of an emulsifier;

(D) (d1) a cross-linking agent in an amount sufficient for cross-linking component (A), and

(d2) a catalyst; and

(E) 0 to 60 parts by weight of a reinforcing silica filler, said method comprising the steps of mixing a mixture of an appropriate amount of component (A) and an appropriate amount of component (E) with an appropriate amount of components (d1) and (d2), loading the obtained mixture together with an appropriate amount of component (B) and an appropriate amount of component (C) into a high-speed stiffer-equipped mixer, and then stirring and mixing the components till a uniform emulsion is formed.

8. A method of manufacturing a silicone rubber comprising the steps of:

heating an emulsion composition comprising;

(A) 100 parts by weight of a diorganopolysiloxane having at least two silicon-bonded alkenyl groups in a molecule;

(B) 10 to 250 parts by weight of water that contains a smectite clay;

(C) 0.1 to 15 parts by weight of an emulsifier;

(D) (d1) a cross-linking agent in an amount sufficient for cross-linking component (A), and

(d2) a catalyst; and

(E) 0 to 60 parts by weight of a reinforcing silica filler, thus forming a wet silicone rubber-like substance, and then

dehydrating the obtained wet silicone rubber-like substance.

9. The method according to claim 8 , wherein the smectite clay is a synthetic saponite.

10. The method according to claim 8 , wherein the component (B) contains the smectite clay in the amount of 1 to 10 parts by weight per 100 parts by weight of the water.

11. The method according to claim 8 , wherein the component (C) comprises a non-ionic surface-active agent.

12. The method according to claim 8 , wherein component (d1) is an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, and wherein component (d2) is a platinum-type catalyst.

13. The method according to claim 8 , further comprising the step of mixing a mixture of components (A) and (E) with other components.

14. A method of manufacturing a silicone rubber comprising heating and dehydrating an emulsion composition comprising:

(A) 100 parts by weight of a diorganopolysiloxane having at least two silicon-bonded alkenyl groups in a molecule;

(B) 10 to 250 parts by weight of water that contains a smectite clay;

(C) 0.1 to 15 parts by weight of an emulsifier;

(D) (d1) a cross-linking agent in an amount sufficient for cross-linking component (A), and

(d2) a catalyst; and

(E) 0 to 60 parts by weight of a reinforcing silica filler.

15. The method according to claim 14 , further comprising the step of mixing a mixture of components (A) and (E) with other components.

16. The method according to claim 14 , wherein the smectite clay is a synthetic saponite.

17. The method according to claim 14 , wherein the component (B) contains the smectite clay in the amount of 1 to 10 parts by weight per 100 parts by weight of the water.

18. The method according to claim 14 , wherein the emulsifyer of component (C) comprises a non-ionic surface-active agent.

19. The method according to claim 14 , wherein component (d1) is an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, and wherein component (d2) is a platinum-type catalyst.

20. The method according to claim 14 , wherein component (E) is a hydrophobically surface-treated reinforcing silica filler.