Ink composition and hardened material using thereof

1. An active energy ray-curable inkjet ink composition comprising:

polymerizable monomers, the polymerizable monomers comprising 60 to 98% by weight of monoethylenically unsaturated monomers, the monoethylenically unsaturated monomers comprising 25 to 65% by weight of isobornyl acrylate and 12.5 to 60% by weight of N-vinyl caprolactam based on the total amount of the polymerizable monomers, and

a resin having an acid value of 50 mg KOH/g or higher and a weight average molecular weight of 1000 to 20000.

2. The active energy ray-curable inkjet ink composition according to claim 1 , wherein said resin has a weight average molecular weight of 1000 to 15,000.

3. A printed matter printed with the active energy ray-curable inkjet ink composition according to claim 1 .

4. The printed matter according to claim 3 , wherein said printed matter is printed on a base material surface treated by introducing a polar group into the surface of the base material.

5. The active energy ray-curable inkjet ink composition according to claim 1 , wherein said resin is present in from 1 to 10% by weight based on the total amount of the polymerizable monomers.

6. The active energy ray-curable inkjet ink composition according to claim 1 , further comprising pigment.

7. The active energy ray-curable inkjet ink composition according to claim 6 , further comprising a pigment dispersant.

8. The active energy ray-curable inkjet ink composition according to claim 1 , wherein said composition has a viscosity at 25° C. of 5 to 200 mPa·s.

9. The active energy ray-curable inkjet ink composition according to claim 6 , wherein said composition has a viscosity at 25° C. of 5 to 200 mPa·s.