Thermosetting silicone composition

1. A thermosetting transparent silicone composition comprising:

(A) a linear organopolysiloxane capped at both ends of the molecular chain with alkenyl groups, which is represented by the structural formula:

R 1 R 2 2 SiO(R 2 2 SiO) n SiR 1 R 2 2 (in the formula, R 1 is an alkenyl group, R 2 are each independently C1-12 alkyl groups, and n is an integer of from 5 to 1500),

(B) a resinous organopolysiloxane having at least two alkenyl groups at the end of the molecular chain, wherein the amount of alkenyl groups in the entire silicon atom-bonded functional group of component (B) is 6 mol % or more with respect to the total amount of the silicon atom-bonded functional group,

(C) an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms at the side chain of the molecular chain, which is represented by the structural formula:

R 4 3 SiO(R 5 2 SiO) m SiR 4 3 (in the formula, R 4 are each independently C1-12 alkyl groups, R 5 are each independently C1-12 alkyl groups or hydrogen atoms, while at least two R 5 are hydrogen atoms, and m is an integer of from 3 to 200),

(D) a curing reaction catalyst; and

(E) a silicone compound functionalized with an epoxy group or an alkoxy group;

wherein component (A) is included in the amount of 60 mass % or more based on the total mass of all the organopolysiloxane component,

wherein the content of organohydrogenpolysiloxane of component (C) is 1.0 to 3.0 mols of silicon atom-bonded hydrogen atoms per 1 mol of silicon atom-bonded alkenyl groups in the composition, and

wherein the composition further comprises methyl-tris(3-methyl-1-butyn-3-oxy)silane as a reaction inhibitor.

2. The thermosetting transparent silicone composition as claimed claim 1 , wherein the resinous organopolysiloxane having at least two alkenyl groups at the end of the molecular chain of component (B) comprises a siloxane unit represented by SiO 1/2 and a siloxane unit represented by SiO 4/2 .

3. An encapsulant of an optical semiconductor device, being cured material of the thermosetting transparent silicone composition described in claim 1 .

4. The thermosetting transparent silicone composition as claimed in claim 1 , wherein R 1 for component (A) is a C2-6 alkenyl group, each R 2 for component (A) is independently a C1-6 alkyl group, and integer n for component (A) ranges from 10 to 1200.

5. The thermosetting transparent silicone composition as claimed claim 1 , wherein the resinous organopolysiloxane of component (B) is represented by the average unit formula (II):

(R 3 3 SiO 1/2 ) a (R 3 2 SiO 2/2 ) b (R 3 SiO 3/2 ) c (SiO 4/2 ) d (XO 1/2 ) e , where in formula (II), each R 3 is independently C1-12 alkyl groups or C2-12 alkenyl groups, while at least two of R 3 are alkenyl groups, X is a hydrogen atom or an alkyl group, 0≤a<1, 0≤b<1, 0≤c<0.9, 0≤d<0.9, 0≤e≤0.2, a+b+c+d=1.0, and c+d>0.

6. The thermosetting transparent silicone composition as claimed claim 5 , wherein each R 3 for component (B) is independently a C1-6 alkyl group or a C2-C6 alkenyl group, and X for component (B) is a hydrogen atom or a C1-3 alkyl group.

7. The thermosetting Previously Presented transparent silicone composition as claimed claim 5 , wherein in formula (II) of component (B), a is in the range of 0.1≤a≤0.8, b is in the range of 0≤b≤0.4, c is in the range of 0≤c≤0.4, and d is in the range of 0.1≤d≤0.8.

8. The thermosetting transparent silicone composition as claimed in claim 1 , wherein the composition is free of silica particles.

9. The thermosetting transparent silicone composition as claimed in claim 1 , wherein the amount of the silicon atom-bonded hydrogen atoms in the entire composition is 0.82 mol % or more.

10. The thermosetting transparent silicone composition as claimed in claim 9 , wherein m in the formula R 4 3 SiO(R 5 2 SiO) m SiR 4 3 is an integer of from 40 to 200.

11. The thermosetting transparent silicone composition as claimed in claim 1 , wherein m in the formula R 4 3 SiO(R 5 2 SiO) m SiR 4 3 is an integer of from 40 to 200.

12. An optical semiconductor device, which is sealed with a cured material of a thermosetting transparent silicone composition comprising:

(A) a linear organopolysiloxane capped at both ends of the molecular chain with alkenyl groups, which is represented by the structural formula:

R 1 R 2 2 SiO(R 2 2 SiO) n SiR 1 R 2 2 (in the formula, R 1 is an alkenyl group, R 2 are each independently C1-12 alkyl groups, and n is an integer of from 5 to 1500),

(B) a resinous organopolysiloxane having at least two alkenyl groups at the end of the molecular chain, wherein the amount of alkenyl groups in the entire silicon atom-bonded functional group of component (B) is 6 mol % or more with respect to the total amount of the silicon atom-bonded functional group,

(C) an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms at the side chain of the molecular chain, which is represented by the structural formula:

R 4 3 SiO(R 5 2 SiO) m SiR 4 3 (in the formula, R 4 are each independently C1-12 alkyl groups, R 5 are each independently C1-12 alkyl groups or hydrogen atoms, while at least two R 5 are hydrogen atoms, and m is an integer of from 3 to 200),

(D) a curing reaction catalyst,

(E) a silicone compound functionalized with an epoxy group or an alkoxy group, and

methyl-tris(3-methyl-1-butyn-3-oxy) silane as a reaction inhibitor,

wherein the content of organohydrogenpolysiloxane of component (C) is 1.0 to 3.0 mols of silicon atom-bonded hydrogen atoms per 1 mol of silicon atom-bonded alkenyl groups in the composition.

13. The optical semiconductor device as claimed claim 12 , wherein the resinous organopolysiloxane of the thermosetting transparent silicone composition which has at least two alkenyl groups at the end of the molecular chain of component (B) comprises a siloxane unit represented by SiO 1/2 and a siloxane unit represented by SiO 4/2 .

14. The optical semiconductor device as claimed in claim 12 , wherein the amount of the silicon atom-bonded hydrogen atoms in the entire composition is 0.82 mol % or more.

15. The optical semiconductor device as claimed in claim 14 , wherein m in the formula R 4 3 SiO(R 5 2 SiO) m SiR 4 3 is an integer of from 40 to 200.

16. The optical semiconductor device as claimed in claim 12 , wherein m in the formula R 4 3 SiO(R 5 2 SiO) m SiR 4 3 is an integer of from 40 to 200.

17. A transparent film obtained by solidifying a thermosetting transparent silicone composition comprising:

(A) a linear organopolysiloxane capped at both ends of the molecular chain with alkenyl groups, which is represented by the structural formula:

R 1 R 2 2 SiO(R 2 2 SiO) n SiR 1 R 2 2 (in the formula, R 1 is an alkenyl group, R 2 are each independently C1-12 alkyl groups, and n is an integer of from 5 to 1500),

(B) a resinous organopolysiloxane having at least two alkenyl groups at the end of the molecular chain, wherein the amount of alkenyl groups in the entire silicon atom-bonded functional group of component (B) is 6 mol % or more with respect to the total amount of the silicon atom-bonded functional group,

(C) an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms at the side chain of the molecular chain, which is represented by the structural formula:

R 4 3 SiO(R 5 2 SiO) m SiR 4 3 (in the formula, R 4 are each independently C1-12 alkyl groups, R 5 are each independently C1-12 alkyl groups or hydrogen atoms, while at least two R 5 are hydrogen atoms, and m is an integer of from 3 to 200),

(D) a curing reaction catalyst,

(E) a silicone compound functionalized with an epoxy group or an alkoxy group, and

methyl-tris(3-methyl-1-butyn-3-oxy) silane as a reaction inhibitor,

wherein the content of organohydrogenpolysiloxane of component (C) is 1.0 to 3.0 mols of silicon atom-bonded hydrogen atoms per 1 mol of silicon atom-bonded alkenyl groups in the composition.

18. The transparent film as claimed in claim 17 , wherein the amount of the silicon atom-bonded hydrogen atoms in the entire composition is 0.82 mol % or more.

19. The transparent film as claimed in claim 18 , wherein m in the formula R 4 3 SiO(R 5 2 SiO) m SiR 4 3 is an integer of from 40 to 200.

20. The transparent film as claimed in claim 17 , wherein m in the formula R 4 3 SiO(R 5 2 SiO) m SiR 4 3 is an integer of from 40 to 200.