Ink pack

1. An ink pack, wherein an ultraviolet curable type inkjet ink composition which contains a compound having a nitroxyl radical, and has 1.2×10 16 to 3.0×10 19 of a spin number of the nitroxyl radical in one milliliter of the ink composition, is sealed in a pack where at least one layer of an aluminum layer or an aluminum alloy layer and at least one layer of a plastic layer are laminated, wherein

the ink composition includes at least one of compound selected from a group consisting of N-vinyl lactams and (meth)acrylamides, and

the compound having the nitroxyl radical in the ink composition includes 4-hydroxy-2,2,6,6-tetramethyl piperidinyl-N-oxyl.

2. The ink pack according to claim 1 , wherein the ink composition includes an acyl phosphine-based photopolymerization initiator.

3. The ink pack according to claim 1 , wherein the content of the 4-hydroxy-2,2,6,6-tetramethyl piperidinyl-N-oxyl in the ink composition is 0.05 to 1 mass % with respect to the total mass of the ink composition.

4. The ink pack according to claim 1 , wherein a material of a surface in direct contact with the ink composition of the ink pack is polypropylene or polyethylene.

5. The ink pack according to claim 1 , wherein an average oxygen amount in one milliliter of the ink composition after the ink composition is sealed in the ink pack for 1 day is 35.mu.g or less.

6. The ink pack according to claim 1 , wherein the ink composition includes copper phthalocyanine.

7. The ink pack according to claim 1 , which is an oxygen impermeable ink pack.

8. The ink pack according to claim 1 , wherein the ink composition includes a compound represented by the following Formula (b-2),

in the Formula (b-2), R 13 represents a hydrogen atom or a methyl group, and X 2 represents a single bond or a divalent linking group.

9. The ink pack according to claim 1 , wherein the ink composition includes N-vinyl caprolactam.

10. The ink pack according to claim 1 , wherein the ink composition includes at least one of compound selected from a group consisting of N-vinyl caprolactam and N-isopropyl acrylamide.

11. The ink pack according to claim 10 , wherein the total content of the N-vinyl caprolactam and N-isopropyl acrylamide in the ink composition is 15 mass % or more with respect to the total mass of the ink composition.

12. The ink pack according to claim 1 , wherein an average oxygen amount in one milliliter of the ink composition after the ink composition is sealed in the ink pack and stored at 20.degree. C. to 30.degree. C. for 30 days or more is 20.mu.g or less.

13. The ink pack according to claim 12 , wherein an average oxygen amount in one milliliter of the ink composition after the ink composition is sealed in the ink pack for 1 day is 35.mu.g or less.

14. The ink pack according to claim 1 , wherein the ink composition includes an oligomer.

15. The ink pack according to claim 14 , wherein the oligomer is urethane (meth)acrylate.