Curable composition, cured article obtained therefrom and process for preparation of the same

1. A curable composition comprising 100 parts by weight of a vinyl monomer (A) and 0.1 to 100 parts by weight of fine polymer particles (B) having a volume average particle size of 0.05 to 1 μm, said fine polymer particles (B) being dispersed in the form of primary particles in said vinyl monomer (A), wherein said vinyl monomer (A) comprises at least one selected from the group consisting of a (meth)acrylate monomer synthesized from an alcohol having 3 or more carbon atoms and (meth)acrylic acid, a hydroxyethyl(meth)acrylate, an aromatic vinyl monomer and a vinyl ether monomer;

the total amount of the (meth)acrylate monomer synthesized from an alcohol having 3 or more carbon atoms and (meth)acrylic acid and the hydroxyethyl(meth)acrylate in said vinyl monomer (A) is more than 50 wt % and not more than 100 wt %;

said fine polymer particles (B) are particles of a core/shell graft copolymer; and

said shell layer comprises a copolymer of 100 wt % in total of shell layer monomers comprising 2 to 90 wt % of at least one monomer (BS-1) selected from the group consisting of an alkoxyalkyl(meth)acrylate, hydroxyalkyl(meth)acrylate and glycidyl(meth)acrylate,

2 to 98 wt % of at least one monomer (BS-2) selected from the group consisting of an alkyl(meth)acrylate, styrene, α-methylstyrene and (meth)acrylonitrile,

0 to 10 wt % of a polyfunctional vinyl monomer (BS-3), and

0 to 10 wt % of other vinyl monomer (BS-4) being copolymerizable with those monomers.

2. The curable composition according to claim 1 , wherein an active oxygen concentration in the curable composition is less than 50 ppm.

3. The curable composition according to claim 1 , wherein said fine polymer particles (B) are particles of a core/shell graft copolymer comprising at least two layers of an elastic core layer being present inside thereof and a shell layer being present at an outermost side thereof, and said elastic core layer comprises a rubber-like polymer having a glass transition temperature of lower than 0° C.

4. The curable composition according to claim 3 , wherein said shell layer monomer comprises styrene as an essential component.

5. A cured article obtained by curing the curable composition according to claim 1 .

6. A (meth)acrylic adhesive composition comprising the curable composition according to claim 1 , 2 to 50 parts by weight of an elastomer being soluble in said vinyl monomer (A), an ethylenically unsaturated carboxylic acid compound and a radical polymerization initiator, wherein

said vinyl monomer (A) comprises, as main components, at least one (meth)acrylate monomer selected from the group consisting of a (meth)acrylate monomer synthesized from an alcohol having 3 or more carbon atoms and (meth)acrylic acid and hydroxyethyl(meth)acrylate.

7. The (meth)acrylic adhesive composition according to claim 6 , wherein said vinyl monomer (A) comprises, as a sub-component, a (meth)acrylate monomer synthesized from an alcohol having one or more and two or less carbon atoms and (meth)acrylic acid.

8. A cured article obtained from the (meth)acrylic adhesive composition of claim 6 , wherein said fine polymer particles (B) are dispersed in the form of primary particles in the cured article.

9. An anaerobic adhesive composition comprising the curable composition according to claim 1 , 0.01 to 12 parts by weight of a hydroperoxide type organic peroxide, 0.01 to 10 parts by weight of an organic sulfimide compound, 0.01 to 3 parts by weight of an amine compound and 0 to 0.2 part by weight of a polymerization inhibitor, wherein said amine compound is at least one selected from the group consisting of N,N-disubstituted arylamines and hydrogenated products of heterocyclic secondary amines, and said polymerization inhibitor is at least one selected from the group consisting of quinones and phenols.

10. The anaerobic adhesive composition according to claim 9 , wherein said vinyl monomer (A) comprises at least one (meth)acrylate monomer selected from the group consisting of a (meth)acrylate monomer synthesized from an alcohol having 3 or more carbon atoms and (meth)acrylic acid and hydroxyethyl(meth)acrylate.

11. A cured article obtained from the anaerobic adhesive composition of claim 9 , wherein said fine polymer particles (B) are dispersed in the form of primary particles in the cured article of the vinyl monomer (A).

12. A photocurable adhesive composition comprising the curable composition according to claim 1 .

13. A process for preparing the curable composition according to claim 1 comprising, in order:

a first step for preparing an aggregate of the fine polymer particles (B) by slow aggregation, a second step for preparing a dispersion by dispersing the fine polymer particles (B) in an organic solvent, and a third step for preparing a curable composition,

wherein said third step comprises, in order, an operation for adding said vinyl monomer (A) in the organic dispersion of the fine polymer particles obtained in said second step, and an operation for removing the organic solvent, and

said operation for removing the organic solvent in the third step is carried out under gas atmosphere comprising an inert gas and oxygen and having an oxygen content of 2 to 8 vol %.

14. The process for preparing the curable composition according to claim 13 , wherein a boiling point of said organic solvent is lower than 60° C.

15. The process for preparing the curable composition according to claim 13 , wherein a pressure of said gas atmosphere comprising an inert gas and oxygen is 260 to 650 mmHg.

16. The process for preparing the curable composition according to claim 13 , wherein said operation for removing the organic solvent is carried out mainly at 20° C. to 51° C.