Curable organopolysiloxane composition for forming film and production method for organopolysiloxane cured product film

1. A curable organopolysiloxane composition for forming a film, comprising:

a curing reactive organopolysiloxane;

a curing agent; and

one or more organic solvents selected from the group consisting of (D1) organic polar solvents, (D2) low molecular weight siloxane solvents, (D3) halogen solvents, and mixed solvents thereof;

wherein the viscosity of the entire composition measured at a shear rate of 0.1 (s −1 ) at 25° C. is 100,000 mPa·s or less, and the viscosity of the entire composition measured at a shear rate of 10.0 (s −1 ) is within a range of 5 to 50,000 mPa·s,

wherein the thixotropic ratio, which is a ratio of the viscosity of the entire composition measured at a shear rate of 0.1 (s −1 ) to the viscosity of the entire composition measured at a shear rate of 10.0 (s −1 ), is 25.0 or less; and

wherein an organopolysiloxane cured product, obtained by curing the curable organopolysiloxane composition, has a dielectric constant measured at 1 KHz and 25° C. of 3 or higher.

2. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein;

(D1) the organic polar solvent is one or more type of organic polar solvent selected from the group consisting of cyclohexanone, isobutyl acetate, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, N,N-dimethylformamide (DMF), N-hexaldehyde, acetone, benzaldehyde, methyl acetate, propyl acetate, acetophenone, pentyl acetate, butyraldehyde, ethyl methyl acetate, ethyl ether, and tetrahydrofuran (THF),

(D2) the low molecular weight siloxane solvent is one or more type of low molecular weight siloxane solvent selected from the group consisting of hexamethyldisiloxane, tetramethyldivinyldisiloxane, 2-methylphenethylpentamethyldisiloxane, octamethyltrisiloxane, and 1,3-difluorotetramethyldisiloxane, and

(D3) the halogen solvent is one or more type of halogen solvent selected from the group consisting of trifluoromethylbenzene, 1,2-bis(trifluoromethyl)benzene, 1,3-bis(trifluoromethyl)benzene, 1,4-bis(trifluoromethyl)benzene, trifluoromethylchlorobenzene, trifluoromethylfluorobenzene, and hydrofluoroether.

3. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein the curing reactive organopolysiloxane and curing agent essentially do not contain halogen atoms, contain one or more type of organic solvent selected from the group consisting of (D1) organic polar solvents, (D2) low molecular weight siloxane solvents, and mixed solvents thereof, and essentially do not contain (D3) halogen solvents.

4. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein the curing reactive organopolysiloxane and curing agent is a methyl polysiloxane composition that essentially does not contain halogen atoms, and contains 50 mol % or more of dimethylsiloxane units of all siloxane units, and the organic solvent contains one or more type of low molecular weight siloxane solvent selected from the group consisting of hexamethyldisiloxane, octamethyltrisiloxane, and a mixture thereof, and essentially does not contain (D3) halogen solvents.

5. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein the curing reactive organopolysiloxane and curing agent contain a halogen atom, contain one or more type of organic solvent selected from the group consisting of (D1) organic polar solvents, (D2) low molecular weight siloxane solvents, (D3) halogen solvents, and mixed solvents thereof.

6. The curable organopolysiloxane composition for forming a film according to claim 5 , wherein the boiling point of the organic solvent is 120° C. or higher.

7. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein the amount of non-volatile solid fraction components forming an organopolysiloxane cured product, obtained by curing the curable organopolysiloxane composition, is within a range of 5 to 95 mass % of the total composition.

8. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein the curing reactive organopolysiloxane and curing agent are cured by one or more type of curing reaction mechanism selected from the group consisting of hydrosilylation reaction curing, condensation reaction curing, radical reaction curing, and high energy beam curing reactions.

9. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein an organopolysiloxane cured product, obtained by curing the curable organopolysiloxane composition, has a dielectric constant measured at 1 KHz and 25° C. of 5 or higher.

10. The curable organopolysiloxane composition for forming a film according to claim 1 , wherein the curing reactive organopolysiloxane and curing agent comprise:

(A) an organopolysiloxane having at least two curing reactive groups containing a carbon-carbon double bond in a molecule;

(B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule; and

(C) an effective amount of a hydrosilylation reaction catalyst.

11. The curable organopolysiloxane composition for forming a film according to claim 10 , wherein component (A) is an organopolysiloxane or mixture thereof comprising:

(a1) a straight-chain or branched-chain organopolysiloxane having an alkenyl group only at an end of a molecular chain; and optionally

(a2) an organopolysiloxane resin containing an alkenyl group having at least one branched siloxane unit in a molecule with an amount of vinyl (CH 2 —CH—) groups within a range of 1.0 to 5.0 mass %.

12. The curable organopolysiloxane composition for forming a film according to claim 10 , wherein a portion or all of component (A) or component (B) is an organopolysiloxane or an organohydrogenpolysiloxane having a high dielectric functional group.

13. The curable organopolysiloxane composition for forming a film according to claim 10 , wherein a portion or all of component (A) or component (B) is an organopolysiloxane or organohydrogenpolysiloxane having a fluoroalkyl group as expressed by (C p F 2P+1 )—R— in a molecule, where R represents an alkylene group with 1 to 10 carbon atoms, and p represents an integer between 1 and 8, and contains one or more type of organic solvent selected from the group consisting of (D1) organic polar solvents, (D3) halogen solvents, and mixed solvents thereof.

14. A method of manufacturing an organopolysiloxane cured film, comprising:

coating the curable organopolysiloxane composition for forming a film according to claim 1 into a thin film form with a thickness after curing within a range of 1 to 1000 μm, on a separator having a release layer;

curing the curable organopolysiloxane composition for forming a film coated into a thin film form; and

removing the organic solvent during or after curing.

15. The method of manufacturing an organopolysiloxane cured film according to claim 14 , further comprising a step of rolling.

16. A film formed from the curable organopolysiloxane composition according to claim 1 .