Composition curable by radical photo curing and cationic photo curing in combination

1. A composition curable by radical photo curing and cationic photo curing in combination, comprising the under-mentioned components (A), (B), (C) and (D) as essential components:

(A) a vinyl polymer having two or more groups represented by general formula (1):

—OC(O)C(R a )=CH 2   (1)

wherein R a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, per molecule, the group represented by general formula (1) being present at one or more molecular ends;

(B) an epoxy compound and/or an oxetane compound;

(C) a radical photopolymerization initiator; and

(D) a cationic photopolymerization initiator, and

wherein the vinyl monomer constituting the main chain of component (A) comprises a (meth)acrylic monomer as a main component and a (meth)acryloyl group exists at the molecular end.

2. The curable composition of claim 1 , wherein the vinyl monomer constituting the main chain of component (A) comprises an acrylic acid ester monomer as a main component.

3. The curable composition of claim 1 , wherein the vinyl monomer constituting the main chain of component

(A) contains at least 2 monomers selected from the group consisting of butyl acrylate, ethyl acrylate and 2-methoxyethyl acrylate.

4. The curable composition of claim 1 , wherein R a is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.

5. The curable composition of claim 4 , wherein R a is a hydrogen atom or a methyl group.

6. The curable composition of claim 1 , wherein component (A) is produced by reacting a compound indicated by general formula (2):

M + -OC(O)C(R a )═CH 2   (2)

wherein R a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms and M + represents an alkali metal ion or a quaternary ammonium ion, with a vinyl polymer having halogen groups at the molecular ends.

7. The curable composition of claim 6 , wherein the vinyl polymer having halogen groups at the molecular ends has a group indicated by general formula (3):

—CR 1 R 2 X  (3)

wherein R 1 and R 2 represent a group bonded to the ethylenically unsaturated group of a vinyl monomer, and X represents a chlorine atom, a bromine atom or an iodine atom.

8. The curable composition of claim 1 , wherein component (A) is produced by reacting a compound indicated by general formula (4):

X 1 —C(O)C(R a )═CH 2   (4)

wherein R a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and X 1 represents a chlorine atom, a bromine atom or a hydroxyl group, with a vinyl polymer having hydroxyl groups at the ends.

9. The curable composition of claim 1 , wherein component (A) is produced by:

(1) reacting a diisocyanate compound with a vinyl polymer having hydroxyl groups at the ends, and

(2) reacting a compound indicated by general formula (5):

HO—R′—OC(O)C(R a )═CH 2   (5)

wherein R a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms and R′ represents a divalent organic group having 2 to 20 carbon atoms, with the residual isocyanate group.

10. The curable composition of claim 1 , wherein the main chain of component (A) is produced by a living radical polymerization of a vinyl monomer.

11. The curable composition of claim 10 , wherein the living radical polymerization is atom transfer radical polymerization.

12. The curable composition of claim 11 , wherein a transition metal complex being the catalyst of the atom transfer radical polymerization is selected from complexes of copper, nickel, ruthenium and iron.

13. The curable composition of claim 12 , wherein the transition metal complex is a complex of copper.

14. The curable composition of claim 1 , wherein the main chain of component (A) is produced by the polymerization of a vinyl monomer using a chain transfer agent.

15. The curable composition of claim 1 , wherein component (A) has a number average molecular weight of 3,000 or more.

16. The curable composition of claim 1 , wherein the vinyl polymer of component (A) has a ratio of weight average molecular weight to number average molecular weight of less than 1.8 determined by gel permeation chromatography.

17. The curable composition of claim 1 , which further contains a monomer and/or an oligomer having a radical polymerizable group.

18. The composition of claim 1 , which further contains a monomer and/or an oligomer having an anionic polymerizable group.

19. The curable composition of claim 17 , which contains a monomer and/or an oligomer having a (meth)acryloyl group.

20. The curable composition of claim 19 , which contains a monomer and/or an oligomer having a (meth)acryloyl group and having a number average molecular weight of 5,000 or less.

21. The curable composition of claim 1 , wherein the epoxy compound and/or oxetane compound of component (B) has no aromatic ring.

22. The curable composition of claim 1 , which further contains (E) a compound having an epoxy group and a (meth)acryloyl group in its molecule.

23. The curable composition of claim 22 , wherein component (E) is glycidyl methacrylate.