Release agent composition

1. A release agent composition comprising a fluorocopolymer comprising structural units based on monomer (a), structural units based on monomer (b), and structural units based on monomer (c), and a medium,

wherein the mass ratio of the structural units based on the monomer (a) to the structural units based on the monomer (b) (the structural units based on the monomer (a)/the structural units based on the monomer (b)) is from 1/2 to 1/5:

monomer (a): a compound represented by formula (1):

(Z—Y) n X  (1)

wherein Z is a C 1-6 polyfluoroalkyl group or a group represented by formula (2),

Y is a bivalent organic group or a single bond,

n is 1 or 2, and

X is any one of groups represented by formulae (3-1) to (3-5) when n is 1, and is any one of groups represented by formulae (4-1) to (4-4) when n is 2:

C m F 2m+1 O(CF 2 CF(CF 3 )O) d CF(CF 3 )—  (2)

wherein m is an integer of from 1 to 6, and d is an integer of from 1 to 4;

—C(R)═CH 2   (3-1),

—C(O)OC(R)═CH 2   (3-2),

—OC(O)C(R)═CH 2   (3-3),

—OCH 2 -φ-C(R)═CH 2   (3-4),

—OCH═CH 2   (3-5)

wherein R is a hydrogen atom, a methyl group or a halogen atom, and φ is a phenylene group;

—CH[—(CH 2 ) p C(R)═CH 2 ]—  (4-1),

—CH[—(CH 2 ) p C(O)OC(R)═CH 2 ]—  (4-2),

—CH[—(CH 2 ) p OC(O)C(R)═CH 2 ]—  (4-3),

—OC(O)CH═CHC(O)O—  (4-4)

wherein R is a hydrogen atom, a methyl group or a halogen atom, and p is an integer of from 0 to 4;

monomer (b): a (meth)acrylate having no polyfluoroalkyl group and having a C 18-30 alkyl group; and

monomer (c): a halogenated olefin.

2. The release agent composition according to claim 1 , wherein the fluorocopolymer further comprises structural units based on monomer (d):

monomer (d): a monomer having no polyfluoroalkyl group and having a crosslinkable functional group.

3. The release agent composition according to claim 1 , which further comprises a nonionic surfactant and a cationic surfactant.

4. The release agent composition according to claim 1 , wherein the medium is at least one aqueous medium selected from the group consisting of water, an alcohol, a glycol, a glycol ether and a glycol ester.

5. The release agent composition according to claim 1 , wherein the fluorocopolymer is dispersed as particles in the medium, and the average particle size of the fluorocopolymer is from 10 to 1,000 nm.

6. The release agent composition according to claim 1 , wherein, in monomer (a), Z is a C 4-6 polyfluoroalkyl group.

7. The release agent composition according to claim 1 , wherein monomer (a) is C 6 F 13 C 2 H 4 OC(O)C(CH 3 )═CH 2 .

8. The release agent composition according to claim 1 , wherein monomer (b) is at least one of stearyl(meth)acrylate and behenyl(meth)acrylate.

9. The release agent composition according to claim 1 , wherein monomer (b) is a mixture of behenyl(meth)acrylate and at least one other (meth)acrylate, where behenyl(meth)acrylate is present in the mixture in an amount of at least 5 mass % based on the entire monomer (b).

10. The release agent composition according to claim 1 , wherein monomer (c) is at least one member selected from the group consisting of vinyl chloride, vinylidene chloride, tetrafluoroethylene, and vinylidene fluoride.

11. The release agent composition according to claim 1 , wherein monomer (c) is vinyl chloride or vinylidene chloride.

12. An article comprising the release agent composition according to claim 1 , wherein the article has a peel strength of 0.1 to 0.6N.

13. An article according to claim 12 , wherein the article has a peel strength of 0.15 to 0.5N.

14. A process for producing a release agent composition, which comprises copolymerizing a monomer mixture containing following monomer (a), monomer (b), and monomer (c) in a mass ratio of the monomer (a) to the monomer (b) (the monomer (a)/the monomer (b)) of from 1/2 to 1/5 in the presence of a polymerization initiator:

monomer (a): a compound represented by formula (1):

(Z—Y) n X  (1)

wherein Z is a C 1-6 polyfluoroalkyl group or a group represented by formula (2),

Y is a bivalent organic group or a single bond,

n is 1 or 2, and

X is any one of groups represented by formulae (3-1) to (3-5) when n is 1, and is any one of groups represented by the formulae (4-1) to (4-4) when n is 2:

C m F 2m+1 O(CF 2 CF(CF 3 )O) d CF(CF 3 )—  (2)

wherein m is an integer of from 1 to 6, and d is an integer of from 1 to 4;

—C(R)═CH 2   (3-1),

—C(O)OC(R)═CH 2   (3-2),

—OC(O)C(R)═CH 2   (3-3),

—OCH 2 -φ-C(R)═CH 2   (3-4),

—OCH═CH 2   (3-5)

wherein R is a hydrogen atom, a methyl group or a halogen atom, and φ is a phenylene group;

—CH[—(CH 2 ) p C(R)═CH 2 ]—  (4-1),

—CH[—(CH 2 ) p C(O)OC(R)═CH 2 ]—  (4-2),

—CH[—(CH 2 ) p OC(O)C(R)═CH 2 ]—  (4-3),

—OC(O)CH═CHC(O)O—  (4-4)

wherein R is a hydrogen atom, a methyl group or a halogen atom, and p is an integer of from 0 to 4;

monomer (b): a (meth)acrylate having no polyfluoroalkyl group and having a C 18-30 alkyl group; and

monomer (c): a halogenated olefin.