Organopolysiloxane, production method thereof, and curable silicone composition

1. An organopolysiloxane represented by the following average unit formula:

(R 1 SiO 3/2 ) a (XR 2 2 SiO 1/2 ) b (O 1/2 SiR 2 2 —Y—R 2 2 SiO 1/2 ) c

wherein,

R 1 and R 2 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons;

X represents an alkenyl group having from 2 to 12 carbons or a siloxane residue represented by the following general formula (1):

HR 3 2 SiO(R 3 2 SiO) n SiR 3 2 —R 4 —

where R 3 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons, R 4 represents an alkylene group having from 2 to 12 carbons, and “n” is a number in a range of 0 to 5, and

Y represents a siloxane linking group represented by the following general formula (2):

—R 4 —R 3 2 SiO(R 3 2 SiO) n SiR 3 2 —R 4 —

where R 3 , R 4 , and “n” are as above; or

X represents an alkenyl group having from 2 to 12 carbons or a silphenylene residue represented by the following general formula (3):

HR 3 2 Si—C 6 H 4 —SiR 3 2 —R 4 —

where R 3 and R 4 are as above, and

Y represents a silphenylene linking group represented by the following general formula (4):

—R 4 —R 3 2 Si—C 6 H 4 —SiR 3 2 —R 4 —

where R 3 and R 4 are as above; and

“a” is a number in a range of 0.65 to 0.90, “b” is a number in a range of 0.10 to 0.35, “c” is a number in a range of 0 to 0.10, and “a”+“b”+“c”=1.00; and

wherein the organopolysiloxane includes at least one siloxane residue represented by formula (1) or the organopolysiloxane includes at least one silphenylene residue represented by formula (3).

2. The organopolysiloxane according to claim 1 , wherein at least 10 mol % of R 1 are aryl groups having from 6 to 20 carbons.

3. The organopolysiloxane according to claim 2 , wherein at least 10 mol % of R 1 are phenyl groups.

4. The organopolysiloxane according to claim 1 , wherein R 4 is an ethylene group.

5. The organopolysiloxane according claim 1 , wherein its refractive index at 25° C. for visible light at 589 nm is 1.50 or higher.

6. A method of producing the organopolysiloxane according to claim 1 , the method comprising subjecting

(A) an organopolysiloxane resin represented by the following average unit formula:

(R 1 SiO 3/2 ) d (R 5 R 2 2 SiO 1/2 ) e

where R 1 and R 2 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons; R 5 represents an alkenyl group having from 2 to 12 carbons; “d” is a number in a range of 0.65 to 0.90, “e” is a number in a range of 0.10 to 0.35, and “d”+“e”=1.00; and

(B)

(B1) a diorganosiloxane represented by the following general formula:

HR 3 2 SiO(R 3 2 SiO) n SiR 3 2 H

where R 3 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons, and “n” is a number in a range of 0 to 5, or

(B2) a disilylbenzene represented by the following general formula:

HR 3 2 Si—C 6 H 4 —SiR 3 2 H

where R 3 is as above;

to a hydrosilylation reaction at an amount so that an amount of silicon atom-bonded hydrogen atoms in component (B) exceeds 1 mol per 1 mol of alkenyl groups in component (A).

7. The method according to claim 6 , wherein at least 10 mol % of R 1 in component (A) are aryl groups having from 6 to 20 carbons.

8. The method according to claim 7 , wherein R 5 in component (A) is a vinyl group.

9. A hydrosilylation curable silicone composition comprising the organopolysiloxane according to claim 1 .

10. A hydrosilylation curable silicone composition comprising:

(I) an organopolysiloxane having at least two alkenyl groups in a molecule;

(II) an organopolysiloxane in an amount that an amount of silicon atom-bonded hydrogen atoms in this component is from 0.1 to 10 mol per 1 mol of alkenyl groups in component (I); and

(III) a hydrosilylation catalyst, in an amount that accelerates curing of the composition;

wherein component (II) is according to claim 1 .

11. The organopolysiloxane according to claim 1 , wherein X is the alkenyl group having from 2 to 12 carbons.

12. The organopolysiloxane according to claim 1 , wherein X is the siloxane residue represented by formula (1).

13. The organopolysiloxane according to claim 1 , wherein Y represents the siloxane linking group represented by formula (2).

14. The organopolysiloxane according to claim 1 , wherein X is the silphenylene residue represented by formula (3).

15. The organopolysiloxane according to claim 1 , wherein Y represents the silphenylene linking group represented by formula (4).

16. The organopolysiloxane according to claim 1 , having at least one siloxane residue represented by formula (1).

17. The organopolysiloxane according to claim 1 , having at least one siloxane residue represented by formula (3).

18. A method of producing an organopolysiloxane represented by the following average unit formula:

(R 1 SiO 3/2 ) a (XR 2 2 SiO 1/2 ) b (O 1/2 SiR 2 2 —Y—R 2 2 SiO 1/2 ) c

wherein,

R 1 and R 2 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons;

X represents a siloxane residue represented by the following general formula (1):

HR 3 2 SiO(R 3 2 SiO) n SiR 3 2 —R 4 —

where R 3 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons, R 4 represents an alkylene group having from 2 to 12 carbons, and “n” is a number in a range of 0 to 5, and

Y represents a siloxane linking group represented by the following general formula (2):

—R 4 —R 3 2 SiO(R 3 2 SiO) n SiR 3 2 —R 4 —

where R 3 , R 4 , and “n” are as above; or

X represents a silphenylene residue represented by the following general formula (3):

HR 3 2 Si—C 6 H 4 —SiR 3 2 —R 4 —

where R 3 and R 4 are as above, and

Y represents a silphenylene linking group represented by the following general formula (4):

—R 4 —R 3 2 Si—C 6 H 4 —SiR 3 2 —R 4 —

where R 3 and R 4 are as above; and

“a” is a number in a range of 0.65 to 0.90, “b” is a number in a range of 0.10 to 0.35, “c” is a number in a range of 0 to 0.10, and “a”+“b”+“c”=1.00;

the method comprising subjecting

(A) an organopolysiloxane resin represented by the following average unit formula:

(R 1 SiO 3/2 )d(R 5 R 2 2 SiO 1/2 ) e

where R 1 and R 2 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons; R 5 represents an alkenyl group having from 2 to 12 carbons; “d” is a number in a range of 0.65 to 0.90, “e” is a number in a range of 0.10 to 0.35, and “d”+“e”=1.00; and

(B)

(B1) a diorganosiloxane represented by the following general formula:

HR 3 2 SiO(R 3 2 SiO) n SiR 3 2 H

where R 3 each independently represent an alkyl group having from 1 to 12 carbons, aryl group having from 6 to 20 carbons, or aralkyl group having from 7 to 20 carbons, and “n” is a number in a range of 0 to 5, or

(B2) a disilylbenzene represented by the following general formula:

HR 3 2 Si—C 6 H 4 —SiR 3 2 H

where R 3 is as above;

to a hydrosilylation reaction at an amount so that an amount of silicon atom-bonded hydrogen atoms in component (B) exceeds 1 mol per 1 mol of alkenyl groups in component (A).

19. The method according to claim 18 , wherein at least 10 mol % of R 1 in component (A) are aryl groups having from 6 to 20 carbons.

20. The method according to claim 19 , wherein R 5 in component (A) is a vinyl group.