Curable white silicone formulation, a reflective material for optical semiconductor module and optical semiconductor device

1. A curable white silicone composition comprising at least: (A) an organopolysiloxane having at least 2 alkenyl groups per molecule,

(B) a cerium-containing organopolysiloxane,

(C) a white pigment, and

(D) a curing catalyst,

wherein the content of the (C) white pigment is 10 to 80% by mass with respect to the total mass of the composition.

2. A curable white silicone composition according to claim 1 , wherein the concentration of cerium atoms in the (B) cerium-containing organopolysiloxane is 0.5 to 1,000 ppm.

3. A curable white silicone composition according to claim 2 , wherein the (C) white pigment has a mean particle size of 0.1 to 5 μm.

4. A curable white silicone composition according to claim 3 , wherein the (A) organopolysiloxane comprises a resinous organopolysiloxane that is represented by

(R 1 3 SiO 1/2 ) f (SiO 4/2 ) g (XO 1/2 ) h   (A-2) average unit formula:

(in the formula, R 1 are the same or different optionally halogen-substituted monovalent hydrocarbon groups, except that at least two R 1 are alkenyl groups, f is an integer from 5 to 1,000), g is an integer from 5 to 1,000, X is a hydrogen atom or an alkyl group, and h is an integer from 0 to 10).

5. A curable white silicone composition according to claim 4 , wherein the (A) organopolysiloxane comprises a resinous organopolysiloxane and a linear organopolysiloxane such that the linear organopolysiloxane/resinous organopolysiloxane content ratio is 1 or more.

6. A curable white silicone composition according to claim 2 , characterized in that the (C) white pigment comprises titanium oxide that has not been surface treated with silica.

7. A curable white silicone composition according to claim 1 , wherein the (C) white pigment has a mean particle size of 0.1 to 5 μm.

8. A curable white silicone composition according to claim 7 , characterized in that the (C) white pigment comprises titanium oxide that has not been surface treated with silica.

9. A curable white silicone composition according to claim 1 , characterized in that the (C) white pigment comprises titanium oxide that has not been surface treated with silica.

10. A curable white silicone composition according to claim 1 , wherein the (D) curing catalyst comprises a hydrosilylation reaction catalyst.

11. A curable white silicone composition according to claim 1 , wherein the (A) organopolysiloxane comprises a resinous organopolysiloxane.

12. A curable white silicone composition according to claim 11 , wherein the resinous organopolysiloxane is represented by

(R 1 3 SiO 1/2 ) f (SiO 4/2 ) g (XO 1/2 ) h   (A-2) average unit formula:

(in the formula, R 1 are the same or different optionally halogen-substituted monovalent hydrocarbon groups, except that at least two R 1 are alkenyl groups, f is an integer from 5 to 1,000), g is an integer from 5 to 1,000, X is a hydrogen atom or an alkyl group, and h is an integer from 0 to 10).

13. A curable white silicone composition according to claim 12 , wherein the (A) organopolysiloxane comprises a resinous organopolysiloxane and a linear organopolysiloxane such that the linear organopolysiloxane/resinous organopolysiloxane content ratio is 1 or more.

14. A curable white silicone composition according to claim 1 , wherein the (A) organopolysiloxane comprises a resinous organopolysiloxane and a linear organopolysiloxane such that the linear organopolysiloxane/resinous organopolysiloxane content ratio is 1 or more.

15. A reflective material for an optical semiconductor device, comprising the cured product of the curable white silicone composition according to claim 1 .

16. An optical semiconductor device, comprising the reflective material for an optical semiconductor device according to claim 15 .