Water/oil repellent composition, method for producing water/oil repellent composition and article

1. A water/oil repellent composition, comprising:

a nonionic surfactant having a melting point of from 50° C. to 55° C.,

a fluorinated copolymer, and

a medium containing water,

wherein the nonionic surfactant is at least one member selected from the group consisting of 50 mol stearyl polyoxyethylene adduct, 40 mol stearyl polyoxyethylene adduct, 60 mol oleyl polyoxyethylene adduct, 50 mol oleyl polyexyethylene adduct, 40 mol oleyl polyoxyethylene adduct and 30 mol behenyl polyoxyethylene adduct, and

wherein the fluorinated copolymer has structural units based on the following monomer (a) and structural units based on the following monomer (b):

monomer (a): represented by (Z—Y) n X, wherein

Z is a perfluoroalkyl group having at most 6 carbon atoms or a group represented by C m F 2m+1 O (CF 2 CF(CF 3 )O) d CF(CF 3 )—, wherein m is an integer of from 1 to 6, and d is an integer of from 1 to 4,

Y is a bivalent organic group or a single bond,

n is 1 or 2; and

X is a polymerizable unsaturated group, and when n is 1, X is —CR═CH 2 , —COOCR═CH 2 , —OCOCR═CH 2 , —OCH 2 -φ-CR═CH 2 or —OCH═CH 2 , and when n is 2, X is ═CH(CH 2 ) q CR═CH 2 , ═CH(CH 2 ) q COOCR═CH 2 , ═CH(CH 2 ) q OCOCR═CH 2 or —OCOCH═CHCOO—, wherein R is a hydrogen atom, a methyl group or a halogen atom, φ is a phenylene group, and q is an integer of from 0 to 4,

monomer (b): an acrylate having a saturated hydrocarbon group having at least 12 carbon atoms or a methacrylate having a saturated hydrocarbon group having at least 12 carbon atoms, and

wherein the content of the nonionic surfactant is from 0.1 to 10 mass %, per 100 mass % of the fluorinated copolymer.

2. The water/oil repellent composition according to claim 1 , wherein the nonionic surfactant is at least one selected from the group consisting of 50 mol stearyl polyoxyethylene adduct, 50 mol oleyl polyexyethylene adduct and 30 mol behenyl polyoxyethylene adduct.

3. The water/oil repellent composition according to claim 1 , which further contains a nonionic surfactant having a melting point of lower than 50° C.

4. The water/oil repellent composition according to claim 1 , wherein in the medium containing water, the fluorinated copolymer forms a fluorinated copolymer emulsion with at least a part of the nonionic surfactant having a melting point of from 50° C. to 55° C., and the fluorinated copolymer emulsion has an average particle size of from 5 nm to 300 nm.

5. A method for producing the water/oil repellent composition of claim 1 , the method comprising:

(1) adding monomers containing a fluorinated monomer and a nonionic surfactant having a melting point of from 50° C. to 55° C. in a medium containing water, followed by emulsion polymerization to obtain a fluorinated copolymer emulsion, and

(2) preparing the water/oil repellent composition by using the fluorinated copolymer emulsion obtained in (1).

6. The method for producing a water/oil repellent composition according to claim 5 , wherein the nonionic surfactant is at least one member selected from the group consisting of 50 mol stearyl polyoxyethylene adduct, 50 mol oleyl polyexyethylene adduct and 30 mol behenyl polyoxyethylene adduct.

7. The method for producing a water/oil repellent composition according to claim 5 , wherein the (1) further contains a nonionic surfactant having a melting point of lower than 50° C.

8. An article of which the surface is treated with the water/oil repellent composition as defined in claim 1 and which has a coating film of the fluorinated copolymer on the surface.