Curable organopolysiloxane composition, optical semiconductor element sealant, and optical semiconductor device

1. A hydrosilylation reaction-curable organopolysiloxane composition comprising

(A) a methylphenylalkenylpolysiloxane that has at least two silicon-bonded alkenyl groups per molecule, wherein diphenylsiloxane units are no more than 5 mole % of the total siloxane units and phenyl groups are at least 20 mole % of the total silicon-bonded organic groups in the molecule,

(B) a methylphenylhydrogenpolysiloxane that has at least two silicon-bonded hydrogen atoms per molecule, wherein diphenylsiloxane units are no more than 5 mole % of the total siloxane units and phenyl groups are at least 20 mole % of the total silicon-bonded organic groups in the molecule, and

(C) a hydrosilylation reaction catalyst,

wherein the diphenylsiloxane units are no more than 5 mole % of the total siloxane units in this composition.

2. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 1 , wherein

component (A) is represented by average unit formula (1):

R a SiO (4−a)/2   (1)

wherein R is C 2 to C 8 alkenyl, methyl, and phenyl, at least 20 mole % thereof is comprised of phenyl groups, and a is a positive number from 0.5 to 2.2; and

component (B) is represented by average unit formula (5):

R 1 b H c SiO (4−b−c)/2   (5)

wherein R 1 is methyl and phenyl, at least 20 mole % thereof is comprised of phenyl groups, b is a positive number from 1.0 to 2.2, and c is a positive number from 0.002 to 1.0.

3. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 2 , wherein component (A) is a mixture of

(A1) a methylphenylalkenylpolysiloxane represented by average unit formula (2):

R d SiO (4−d)/2   (2)

wherein R is C 2 to C 8 alkenyl, methyl, and phenyl, at least 20 mole % thereof is comprised of phenyl groups, and d is a positive number from 1.9 to 2.2 that has at least two silicon-bonded C 2 to C 8 alkenyl groups per molecule, is liquid at ambient temperature and has a viscosity at 25° C. of 10 to 100,000 mPa·s, with the proviso that diphenylsiloxane units are no more than 5 mole % of the total siloxane units therein, and

(A2) an organopolysiloxane resin represented by average unit formula (3):

R e SiO (4−e)/2   (3)

wherein R is C 2 to C 8 alkenyl, methyl, and phenyl, at least 20 mole % thereof is comprised of phenyl groups, and e is a positive number from 0.5 to 1.7 that is a solid at ambient temperature and has at least two silicon-bonded alkenyl groups per molecule, with the proviso that diphenylsiloxane units are no more than 5 mole % of the total siloxane units therein,

wherein component (A1) is 99 to 30 weight % of the mixture and component (A2) is 1 to 70 weight % of the mixture and their total is 100 weight %.

4. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 1 , wherein neither component (A) nor component (B) contains the diphenylsiloxane unit.

5. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 3 , wherein neither component (A1) nor component (A2) nor component (B) contains the diphenylsiloxane unit.

6. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 1 , wherein said composition forms a cured product that has an optical transmittance of at least 99% in a quartz cell at a wavelength of 450 nm and an optical path length of 0.2 cm and that has a refractive index at 25° C. for visible light at 589 nm of at least 1.5.

7. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 3 , wherein said composition forms a cured product that has an optical transmittance of at least 99% in a quartz cell at a wavelength of 450 nm and an optical path length of 0.2 cm and that has a refractive index at 25° C. for visible light at 589 nm of at least 1.5.

8. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 6 , wherein the cured product has an optical transmittance of at least 98% at 25° C. at an optical path length of 0.2 cm and a wavelength of 450 nm after the cured product has been held for 1000 hours in a convection oven at 150° C.

9. An optical semiconductor element sealant comprising the hydrosilylation reaction-curable organopolysiloxane composition according to claim 6 .

10. An optical semiconductor element sealant comprising the hydrosilylation reaction-curable organopolysiloxane composition according to claim 7 .

11. The optical semiconductor element sealant according to claim 9 , wherein said sealant forms a cured product that has an optical transmittance at 25° C. of at least 99% at a wavelength of 450 nm and an optical path length of 0.2 cm, wherein this cured product has an optical transmittance at 25° C. of at least 98% at a wavelength of 450 and an optical path length of 0.2 cm after the cured product has been held for 1000 hours in a convection oven at 150° C.

12. An optical semiconductor device, wherein the optical semiconductor element of an optical semiconductor device comprising an optical semiconductor element in a housing is sealed with the transparent cured product from the optical semiconductor element sealant according to claim 9 by filling the optical semiconductor element sealant into the housing and curing.

13. The optical semiconductor device according to claim 12 , wherein the optical semiconductor element is a light-emitting diode element and the optical semiconductor device is a light-emitting diode device.

14. The optical semiconductor device according to claim 12 , wherein the housing is composed of a polar group-containing plastic.

15. The optical semiconductor device according to claim 14 , wherein the polar group-containing plastic is a polyphthalamide resin.

16. The hydrosilylation reaction-curable organopolysiloxane composition according to claim 1 , wherein a total content of 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylcyclotetrasiloxane is no more than 5 weight %.

17. The optical semiconductor element sealant according to claim 9 , wherein a total content of 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetraphenylcyclotetrasiloxane is no more than 5 weight %.

18. An optical semiconductor device, wherein the light-emitting semiconductor element of an optical semiconductor device comprising an optical semiconductor element in a housing is sealed with the transparent cured product from the optical semiconductor element sealant according to claim 17 by filling the optical semiconductor element sealant into the housing and curing.