Inkjet ink composition

1. An inkjet-recording ink composition, comprising, as principal components, one or more white pigment(s), one or more polymer dispersant(s), one or more photocurable compound(s), and one or more photoinitiator(s), wherein the polymer dispersant(s) contain a sulfonic acid group, and

the polymer dispersant(s) are prepared by a polymerization reaction using a long-chain polyol as one component, the long chain polyol containing —SO 3 M as a polar group, wherein M represents a hydrogen atom, an alkali metal, or ammonium.

2. The inkjet-recording ink composition of claim 1 , wherein the photocurable compound(s) contains: a cationic polymerizable compound at least containing an oxirane or oxetane group; or a radical polymerizable compound at least containing an acryl or methacryl group.

3. The inkjet-recording ink composition of claim 1 , wherein the average diameter of the white pigment particles is 0.05 to 1.0 μm.

4. The inkjet-recording ink composition of claim 1 , wherein the sulfonic acid group in the polymer dispersant(s) includes a sulfamine group.

5. The inkjet-recording ink composition of claim 1 , wherein the weight-average molecular weight of the polymer dispersant(s) is 200,000 or less.

6. The inkjet-recording ink composition of claim 1 , wherein the amount of the polymer dispersant(s) added is 1 to 10 wt % with respect to the pigment(s).

7. The inkjet-recording ink composition of claim 2 , wherein the radical polymerizable compound contains: (a) at least one trifunctional or higher (meth)acrylate; and (b) at least one compound selected from monofunctional and bifunctional (meth)acrylates; and the mixing molar ratio (a):(b) is from 15:85 to 40:60.

8. The inkjet-recording ink composition of claim 2 , wherein the cationic polymerizable compound contains an oxetane compound having one to four oxetane rings in its structure.

9. The inkjet-recording ink composition of claim 1 , wherein the photoinitiator(s) is/are a photo acid generator.

10. The inkjet-recording ink composition of claim 9 , wherein the photo acid generator is contained in the ink composition in an amount of 0.1 to 20 wt %.

11. The inkjet-recording ink composition of claim 1 , further comprising a polymerization inhibitor.

12. The inkjet-recording ink composition of claim 1 , wherein the surface tension of the ink composition is 20 to 30 mN/in.