Organic fine particle

1 . An organic particle comprising a core polymer and a shell polymer, wherein

the core polymer has a Tg or a melting point of 15° C. or more,

the core polymer has a water contact angle of 100° or more,

all monofunctional monomers constituting the core polymer are a hydrophobic core monomer of which homopolymer has a water contact angle of 100° or more,

the shell polymer has a Tg or a melting point lower than Tg or the melting point of the core polymer,

the shell polymer has a water contact angle of less than 100°,

all monofunctional monomers constituting the shell polymer are a water-insoluble shell monomer of which homopolymer is water-insoluble

the core polymer is a non-fluorine polymer,

the water-insoluble shell monomer has at least one hydrocarbon group having 1 to 10 carbon atoms or fluoroalkyl group having 1 carbon atom, and

the organic particle has an average particle size of 10 nm to 5,000 nm.

2 . The organic particle according to claim 1 , wherein

the core polymer comprises a repeating unit derived from a crosslinkable core monomer having at least two ethylenically unsaturated double bonds, and

the shell polymer is free of a repeating unit derived from a crosslinkable shell monomer having at least two ethylenically unsaturated double bonds.

3 . The organic particle according to claim 1 , wherein

the core polymer comprises a repeating unit derived from a crosslinkable core monomer having at least two ethylenically unsaturated double bonds, and

the shell polymer has a Tg or a melting point lower than the 10% thermal decomposition temperature of the core polymer.

4 . The organic particle according to claim 1 , wherein the hydrophobic core monomer is free of a reactive/hydrophilic monomer having an ethylenically unsaturated double bond and at least one reactive group and/or hydrophilic group.

5 . The organic particle according to claim 1 , wherein the hydrophobic core monomer is free of glycidyl (meth)acrylate, glycerol (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, acrylic acid, methacrylic acid, trimethylsilyl (meth)acrylate, 2-(trimethylsilyloxy)ethyl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 2-(tert-butylamino)ethyl (meth)acrylate, a dimethylaminoethyl methacrylate quaternary compound and tetrahydrofurfuryl (meth)acrylate.

6 . The organic particle according to claim 1 , wherein the homopolymer of the water-insoluble shell monomer has a solubility in water at 25° C. of 10 g/l or less.

7 . The organic particle according to claim 1 , wherein the hydrophobic core monomer has at least one hydrocarbon group having 4 to 40 carbon atoms.

8 . The organic particle according to claim 1 , wherein the hydrophobic core monomer is represented by the formula:

CH 2 ═C(—R 12 )—C(═O)—Y 11 —(R 11 ) k or

CH 2 ═C(—R 22 )—Y 21 —(H) 5-l —(R 21 ) l

wherein R 11 is an aliphatic hydrocarbon group having 11 to 40 carbon atoms,

R 21 is a hydrocarbon group having 3 to 30 carbon atoms,

R 12 and R 22 are each independently a hydrogen atom, a monovalent organic group or a halogen atom other than fluorine,

Y 11 is a divalent to tetravalent group composed of at least one selected from a direct bond, a divalent to tetravalent hydrocarbon group having 1 carbon atom, —C 6 H 4 —, —O—, —C(═O)—, —S(═O) 2 — and —NR′—, where R′ is H or a hydrocarbon group having 1 to 4 carbon atoms,

Y 21 is a group formed by removing l+1 hydrogen atoms from a benzene ring,

H is a hydrogen atom,

H and R 21 are each directly bonded to Y 21 , and

k and l are each independently 1 to 3.

9 . The organic particle according to claim 1 , wherein the water-insoluble shell monomer is represented by the formula:

CH 2 ═C(—R 32 )—C(═O)—Y 31 —(R 31 ) m or

CH 2 ═C(—R 42 )—Y 41 —(H) 5-n —(R 41 ) n

wherein R 31 is an aliphatic hydrocarbon group having 1 to 10 carbon atoms or —(CH 2 ) i R 33 , where R 33 is a fluoroalkyl group having 1 carbon atom and i is 1 to 6,

R 41 is a hydrocarbon group having 1 to 2 carbon atoms,

R 32 and R 42 are each independently a hydrogen atom, a monovalent organic group or a halogen atom,

Y 31 is a divalent to tetravalent group composed of at least one selected from a direct bond, a divalent to tetravalent hydrocarbon group having 1 carbon atom, —C 6 H 4 —, —O—, —C(═O)—, —S(═O) 2 — and —NR′—, where R′ is H or a hydrocarbon group having 1 to 4 carbon atoms,

Y 41 is a group formed by removing n+1 hydrogen atoms from a benzene ring,

H is a hydrogen atom,

H and R 41 are each directly bonded to Y 41 , and

m is 1 to 3 and n is 0 to 3.

10 . The organic particle according to claim 1 , wherein

the repeating unit derived from the hydrophobic core monomer is 70 parts by mole or more based on 100 parts by mole in total of the repeating units in the core polymer, and

the repeating unit derived from the water-insoluble shell monomer is 70 parts by mole or more based on 100 parts by mole in total of the repeating units in the shell polymer.

11 . A surface coating structure, comprising the organic particle according to claim 1 arranged on a surface of a substrate.

12 . A water-repellent composition which is a dispersion of an organic particle, the composition comprising:

the organic fine particle according to claim 1 ; and

a liquid medium.

13 . A method for forming a surface coating structure, comprising applying a treatment liquid comprising the water-repellent composition according to claim 12 to a substrate.