Curable silicone composition and cured product thereof

1. A curable silicone composition comprising:

(A) from about 40 to about 60 parts by mass of a silicone resin consisting essentially of R 3 SiO 1/2 siloxane units and SiO 4/2 siloxane units, wherein each R is the same or different, and independently selected from halogen-substituted or unsubstituted monovalent hydrocarbon groups free of aliphatic unsaturated bonds, and the mole ratio of R 3 SiO 1/2 siloxane units to SiO 4/2 siloxane units in the silicone resin having a value of from about 0.6 to about 1.5;

(B) from about 60 to about 40 parts by mass of an organopolysiloxane having at least two alkenyl groups per molecule and free of SiO 4/2 siloxane units in the organopolysiloxane, with the proviso that the total amount of components (A) and (B) is 100 parts by mass;

(C) an organosiloxane having at least three silicon atom-bonded hydrogen atoms per molecule, in an amount of the organosiloxane being sufficient enough to provide a molar ratio of silicon atom-bonded hydrogen atoms of component (C) to the alkenyl groups in component (B) in the range of from about 1.0 to about 3.0; wherein component (C) comprises a silicone resin consisting essentially of R 2 HSiO 1/2 siloxane units and SiO 4/2 siloxane units, wherein each R is independently selected and as described above, and the mole ratio of R 2 HSiO 1/2 siloxane units to SiO 4/2 siloxane units in the silicone resin having a value of from about 1.5 to about 4.0; and

(D) a hydrosilylation catalyst in an amount sufficient to initiate curing of the composition.

2. The curable silicone composition according to claim 1 , wherein

the mole ratio of R 2 HSiO 1/2 siloxane units to SiO 4/2 siloxane units in the silicone resin has a value of from about 1.8 to about 3.0.

3. The curable silicone composition according to claim 1 , further comprising:

(E) a reaction inhibitor in an amount sufficient to control curing the composition.

4. The curable silicone composition according to claim 1 , further comprising:

(F) an organosiloxane having two silicon atom-bonded hydrogen atoms per molecule, in an amount such that the silicon atom-bonded hydrogen atoms in the organosiloxane in the total silicon atom-bonded hydrogen atoms in components (C) and (F) is not more than 40 mole %.

5. A method of forming a cured product, the method comprising injection molding the curable silicone composition according to claim 1 .

6. A cured product obtained by curing the curable silicone composition according to claim 1 .

7. The cured product according to claim 6 , wherein a durometer of the cured product is less than Shore A 15 and the tensile strength is greater than 150 psi.

8. The curable silicone composition according to claim 2 , further comprising:

(E) a reaction inhibitor in an amount sufficient to control curing the composition.

9. The curable silicone composition according to claim 8 , further comprising:

(F) an organosiloxane having two silicon atom-bonded hydrogen atoms per molecule, in an amount such that the silicon atom-bonded hydrogen atoms in the organosiloxane in the total silicon atom-bonded hydrogen atoms in components (C) and (F) is not more than 40 mole %.

10. The curable silicone composition according to claim 3 , further comprising:

(F) an organosiloxane having two silicon atom-bonded hydrogen atoms per molecule, in an amount such that the silicon atom-bonded hydrogen atoms in the organosiloxane in the total silicon atom-bonded hydrogen atoms in components (C) and (F) is not more than 40 mole %.

11. A curable silicone composition comprising:

(A) from about 40 to about 60 parts by mass of a silicone resin consisting essentially of R 3 SiO 1/2 siloxane units and SiO 4/2 siloxane units, wherein each R is the same or different, and independently selected from halogen-substituted or unsubstituted monovalent hydrocarbon groups free of aliphatic unsaturated bonds, and the mole ratio of R 3 SiO 1/2 siloxane units to SiO 4/2 siloxane units in the silicone resin having a value of from about 0.6 to about 1.5;

(B) from about 60 to about 40 parts by mass of an organopolysiloxane having at least two alkenyl groups per molecule and free of SiO 4/2 siloxane units in the organopolysiloxane, with the proviso that the total amount of components (A) and (B) is 100 parts by mass;

(C) an organosiloxane having at least three silicon atom-bonded hydrogen atoms per molecule, in an amount of the organosiloxane being sufficient enough to provide a molar ratio of silicon atom-bonded hydrogen atoms of component (C) to the alkenyl groups in component (B) in the range of from about 1.0 to about 3.0;

(D) a hydrosilylation catalyst in an amount sufficient to initiate curing of the composition; and

(F) an organosiloxane having two silicon atom-bonded hydrogen atoms per molecule, in an amount such that the silicon atom-bonded hydrogen atoms in the organosiloxane in the total silicon atom-bonded hydrogen atoms in components (C) and (F) is not more than 40 mole %.

12. The curable silicone composition according to claim 11 , further comprising:

(E) a reaction inhibitor in an amount sufficient to control curing the composition.

13. A method of forming a cured product, the method comprising injection molding the curable silicone composition according to claim 11 .

14. A cured product obtained by curing the curable silicone composition according to claim 11 .

15. The cured product according to claim 14 , wherein a durometer of the cured product is less than Shore A 15 and the tensile strength is greater than 150 psi.