USE OF EPOXY-FUNCTIONAL SILANES AS ADHESION ADDITIVES FOR CATIONICALLY RADIATION CURING SILICONE RELEASE COATINGS

1 . A method of improving the adhesion of radiation-cured adhesive silicone release coatings on films or polymer-coated paper, which method comprises adding as adhesion additives, at least one epoxy-functional silane of the general formula (III)

in which

R 1 , R 2 , and R 3 radicals are identical or different alkyl, alkoxy, aryl, or aryloxy radicals having 1 to 20 carbon atoms, or alkenyl radicals having 2 to 20 carbon atoms, at least one radical being an alkoxy or aryloxy group,

R 4 radicals are alkenyl radicals having 2 to 20 carbon atoms, and optionally comprise ether, ester, urethane or amide groups,

R 5 radicals are H or alkyl groups having 1 to 20 carbon atoms, and

R 6 radicals are H, alkyl groups having 1 to 20 carbon atoms or alkylene groups having 2 to 5 carbon atoms which with R 4 form a cyclic ring.

2 . The method of claim 1 , wherein:

R 1 , R 2 , and R 3 radicals are identical or different alkyl, alkoxy, aryl, or aryloxy radicals having 1 to 4 carbon atoms, or alkenyl radicals having 2 to 4 carbon atoms, at least one radical being an alkoxy or aryloxy group,

R 4 radicals are alkenyl radicals having 2 to 4 carbon atoms, and optionally comprise ether, ester, urethane or amide groups,

R 5 radicals are H or alkyl groups having 1 to 4 carbon atoms, and

R 6 radicals are H, alkyl groups having 1 to 4 carbon atoms.

3 . The method of claim 2 , wherein:

R 1 , R 2 , and R 3 radicals are identical or different and are methoxy or ethoxy,

R 4 radicals are alkenyl radicals having 2 carbon atoms, and optionally comprise ether, ester, urethane or amide groups,

R 5 radicals are H or methyl, and

R 6 radicals are H or methyl.

4 . The method as claimed in claim 1 , wherein at least one adhesion additive compound is selected from the group consisting of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

5 . The method as claimed in claim 4 , wherein the adhesion additive of the general formula (III) is present in a concentration of 0.1 to 10 percent by weight, based on the total composition.

6 . The method as claimed in claim 1 , wherein the radiation-cured silicone release coatings comprise at least one component of the general formula (IV)

in which

R 7 radicals are alkenyl groups having 2 to 20 carbon atoms, and optionally comprise ether, ester, urethane or amide groups, or

are polyether radicals of the general formula (V)

—(CH 2 ) n —[CH 2 —CH(R 8 ) —O] m —H  (V)

R 8 radicals are identical or different radicals from the following group:

alkyl radicals having 1-20 carbon atoms, H, or aryl radicals having 6-20 carbon atoms,

n is 3-10,

m is 1-100,

r is 0 to 1000,

s is 0.1 to 100, and

t is 1 to 100.

7 . The method of claim 6 , wherein:

R 7 radicals are alkenyl groups having 2 to 4 carbon atoms, and optionally comprise ether, ester, urethane or amide groups;

or

R 8 radicals are identical or different radicals from the following group:

alkyl radicals having 1-4 carbon atoms, H, or aryl radicals having 6-10 carbon atoms,

n is 3-10,

m is 1-100,

r is 2 to 200,

s is 0.1 to 10, and

t is 2 to 40.

8 . The method of claim 7 , wherein:

R 7 radicals are alkenyl groups having 2 carbon atoms, and optionally comprise ether, ester, urethane or amide groups.

9 . The method of claim 7 , wherein:

R 8 radicals are identical or different radicals from the following group:

methyl, H, or aryl radicals having 6 carbon atoms.

10 . The method as claimed in claim 4 , wherein the cationically radiation-curing silicone release coatings comprise at least one component of the general formula (IV)

in which

R 7 radicals are alkenyl groups having 2 to 20 carbon atoms, and optionally comprise ether, ester, urethane or amide groups, or

are polyether radicals of the general formula (V)

—(CH 2 ) n —[CH 2 —CH(R 8 )—O] m —H  (V)

R 8 radicals are identical or different radicals from the following group:

alkyl radicals having 1-20 carbon atoms, H, or aryl radicals having 6-20 carbon atoms,

n is 3-10,

m is 1-100,

r is 0 to 1000,

s is 0.1 to 100, and

t is 1 to 100.

11 . The method of claim 10 , wherein:

R 7 radicals are alkenyl groups having 2 carbon atoms, and optionally comprise ether, ester, urethane or amide groups,

n is 3-10,

m is 1-100,

r is 2 to 200,

s is 0.1 to 10, and

t is 2 to 40.

12 . The method of claim 10 , wherein:

R 8 radicals are identical or different radicals from the following group:

methyl, H, or aryl radicals having 6 carbon atoms,

n is 3-10,

m is 1-100,

r is 2 to 200,

s is 0.1 to 10, and

t is 2 to 40.

13 . A radiation-cured adhesive silicone release coating for a substrate, which comprises:

(i) at least one silicone component of the general formula (IV)

in which

R 7 radicals are alkenyl groups having 2 to 20 carbon atoms, and optionally comprise ether, ester, urethane or amide groups, or

are polyether radicals of the general formula (V)

—(CH 2 ) n —[CH 2 —CH(R 8 )—O] m —H  (V)

R 8 radicals are identical or different radicals from the following group:

alkyl radicals having 1-20 carbon atoms, H, or aryl radicals having 6-20 carbon atoms,

n is 3-10,

m is 1-100,

r is 0 to 1000,

s is 0.1 to 100, and

t is 1 to 100; and

(ii) an adhesion additive which comprises at least one epoxy-functional silane of the general formula (III)

in which

R 1 , R 2 , and R 3 radicals are identical or different alkyl, alkoxy, aryl, or aryloxy radicals having 1 to 20 carbon atoms, or alkenyl radicals having 2 to 20 carbon atoms, at least one radical being an alkoxy or aryloxy group,

R 4 radicals are alkenyl radicals having 2 to 20 carbon atoms, and optionally comprise ether, ester, urethane or amide groups,

R 5 radicals are H or alkyl groups having 1 to 20 carbon atoms, and

R 6 radicals are H, alkyl groups having 1 to 20 carbon atoms or alkylene groups having 2 to 5 carbon atoms which with R 4 form a cyclic ring,

wherein:

the adhesive silicone release coatings when applied to a substrate, provide a release force of about 50 to 60 cN/inch and passes the rub-off test within 5 minutes at room temperature upon completion of curing of the silicone release coating.

14 . The radiation-cured adhesive silicone release coating of claim 13 , wherein:

the at least one silicone component of the general formula (IV) of (i) has

R 7 radicals are alkenyl groups having 2 carbon atoms, and optionally comprise ether, ester, urethane or amide groups,

n is 3-10,

m is 1-100,

r is 2 to 200,

s is 0.1 to 10, and

t is 2 to 40; and

the at least one adhesion additive compound is selected from the group consisting of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

15 . The radiation-cured adhesive silicone release coating of claim 13 , wherein:

the at least one silicone component of the general formula (V) of (i) has

R 8 radicals are identical or different radicals from the following group:

methyl, H, or aryl radicals having 6 carbon atoms,

n is 3-10,

m is 1-100,

r is 2 to 200,

s is 0.1 to 10, and

t is 2 to 40; and

the at least one adhesion additive compound is selected from the group consisting of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

16 . The radiation-cured adhesive silicone release coating of claim 14 , wherein:

the adhesive silicone release coatings when applied to a substrate, provide a release force of about 53 to 58 cN/inch and passes the rub-off test within 1 minute at room temperature upon completion of curing of the silicone release coating.

17 . The radiation-cured adhesive silicone release coating of claim 15 , wherein:

the adhesive silicone release coatings when applied to a substrate, provide a release force of about 53 to 58 cN/inch and passes the rub-off test within 1 minute at room temperature upon completion of curing of the silicone release coating.

18 . The radiation-cured adhesive silicone release

coating of claim 13 , wherein the substrate is a film or polymer-coated paper.

19 . The radiation-cured adhesive silicone release coating of claim 16 , wherein the substrate is a film or polymer-coated paper.

20 . The radiation-cured adhesive silicone release coating of claim 17 , wherein the substrate is a film or polymer-coated paper.