CURABLE ORGANOPOLYSILOXANE COMPOSITION, A USE THEREOF, AND A LAMINATE PREPARED FROM THE COMPOSITION

1 . A curable organopolysiloxane composition comprising:

(A) an organopolysiloxane having at least two alkenyl groups in each molecule;

(B) an organohydrogenpolysiloxane in an amount sufficient to provide a value of 1.1:1 to 20:1 (Si—H:alkenyl group) for the molar ratio of silicon-bonded hydrogen atoms in the organohydrogenpolysiloxane to the alkenyl groups in component (A), wherein component (B) consists of the following components (B1) and (B2) at a mass ratio of (B1)/(B2) in the range from 100/0 to 15/85:

(B1) an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms in each molecule and a silicon-bonded hydrogen content [Si—H] mass % satisfying the following equation:

0<[Si—H]mass %<5/(DP) 0.5

wherein DP designates the average number of siloxane units in each molecule calculated by the number average molecular weight of component (B1), and the DP is in the range from 5 to 1000;

(B2) an organohydrogenpolysiloxane having at least one silicon-bonded hydrogen atom in each molecule, which is different from component (B1); and

(C) a hydrosilation reaction catalyst in a catalytic amount.

2 . The curable organopolysiloxane composition according to claim 1 , wherein 50 mol % or more of all the terminal siloxy-groups of component (B1) have at least one silicon-bonded hydrogen atom.

3 . The curable organopolysiloxane composition according to claim 1 , wherein the [Si—H]mass % of component (B1) satisfies following equation:

0<[Si—H]mass %<3.5/(DP) 0.5

and the DP is in the range from 5 to 500.

4 . The curable organopolysiloxane composition according to claim 1 , wherein the composition further comprises an organopolysiloxane resin comprising R 3 SiO 0.5 units and at least one of RSiO 1.5 units or SiO 2.0 units, where R is independently a monovalent organic group or a hydroxyl group or an alkoxy group, and the content of the organopolysiloxane resin is less than 40 mass % of the total amount of the solid components of the composition.

5 . The curable organopolysiloxane composition according to claim 4 , wherein:

component (A) is (A1) a linear organopolysiloxane having at least two alkenyl groups in each molecule with an alkenyl content in the range of from 0.005 to 1.50 mass %;

component (B) is (B1′) a linear organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms, wherein the average number (DP) of siloxane units in each molecule calculated from the number average molecular weight is in the range from 8 to 300, 50 mol % or more of all the terminal siloxy-groups of component (B1′) have at least one silicon-bonded hydrogen atom, and the [Si—H] mass % of component (B1′) satisfies the following equation:

0<[Si—H]mass %<3.5/(DP) 0.5

and;

the content of the organopolysiloxane resin, where R is independently a monovalent organic group, is equal to or less than 20 mass % of the total amount of the solid components contained in the composition.

6 . The curable organopolysiloxane composition according to claim 1 , wherein when a cured layer having a thickness of 30 μm is formed from the composition on a polyethylene terephthalate film having a thickness of 75 μm, the adhesive strength of the cured layer to the film is in the range from 0.5 to 20.0 gf/25 mm as measured according to the 180-degree peel test method specified in the Japanese Industrial Standards Z 0237.

7 . The curable organopolysiloxane composition according to claim 1 , wherein when a cured layer having a thickness of 30 μm is formed from the composition on a polyethylene terephthalate film having a thickness of 75 μm, the adhesive strength of the cured layer to the film is in the range from 0.5 to 15.0 gf/25 mm as measured according to the 180-degree peel test method specified in the Japanese Industrial Standards Z 0237.

8 . The curable organopolysiloxane composition according claim 1 , wherein the composition is substantially free from an organopolysiloxane resin comprising R 3 SiO 0.5 units and at least one of RSiO 1.5 units or SiO 2.0 units, where R is independently a monovalent organic group, and when a cured layer having a thickness of 30 μm is formed from the composition on a polyethylene terephthalate film having a thickness of 75 μm, the adhesive strength of the cured layer to the film is in the range from 0.5 to 10.0 gf/25 mm as measured according to the 180-degree peel test method specified in the Japanese Industrial Standards Z 0237.

9 . A primer composition, an adhesive composition, or a coating composition, with the composition comprising the curable organopolysiloxane composition according claim 1 .

10 . A pressure-sensitive adhesive (PSA) composition consisting of a cured composition formed from the curable organopolysiloxane composition according to claim 1 .

11 . A release coating composition consisting of the curable organopolysiloxane composition according to claim 1 .

12 . An article comprising a layer of cured organopolysiloxane composition which is prepared by curing the curable organopolysiloxane composition according to claim 1 .

13 . A laminate comprising a substrate and a layer of cured organopolysiloxane composition, which is prepared by curing the curable organopolysiloxane composition according to claim 1 in the form of a thin film.

14 . The laminate according to claim 13 , wherein the layer of the cured composition is at least one selected from the group consisting of an adhesive layer, a release coating layer, and a primer layer.

15 . An optical article comprising the laminate according to claim 13 .

16 . A protective film comprising the laminate according to claim 13 .

17 . A pressure-sensitive adhesive composition comprising the curable organopolysiloxane composition according to claim 1 or a cured product thereof.