Curable composition and cured product

1. A curable composition, comprising

surface-modified metal oxide particles (A), which are metal oxide particles having (meth)acryloyl group-containing surface-modifying groups on surface thereof,

a compound (B) which is a (meth)acryloyl group-containing compound comprising a fluorine atom,

a compound (C) which is a (meth)acryloyl group-containing compound comprising at least two (meth)acryloyl-containing groups and said (meth)acryloyl-containing group comprises a urethane bond or —OCH 2 CH(OH)CH 2 —, and having a mass average molecular weight of at least 1,000,

a compound (D) which is a (meth)acryloyl group-containing compound comprising at least one (meth)acryloyl-containing group and said (meth)acryloyl-containing group comprises no unsaturated bond-containing ring structure, and

a polymerization initiator (E),

wherein

per 100 mass % of a total mass of said particles (A), said component (B), said component (C), and said component (D), said particles (A) are from 20 to 45 mass %, said compound (B) is from 0.01 to 20 mass %, said compound (C) is from 10 to 50 mass %, and said compound (D) is from 10 to 50 mass %, and

said polymerization initiator (E) is from 0.01 to 10 parts by mass per 100 parts by mass of the total mass of said particles (A), said component (B), said component (C), and said component (D).

2. The curable composition according to claim 1 , wherein the (meth)acryloyl group-containing surface modifying groups have a group represented by formula (A1),

CH 2 ═CR 1 C(O)—X—(CH 2 ) a —SiR 2 b (—*) 3-b   (A1)

where * is a bond of Si, R 1 is a hydrogen atom or a methyl group, R 2 is a hydrogen atom or a C 1-4 hydrocarbon group, X is —O— or —NH—, a is an integer of from 2 to 7, and b is an integer of from 0 to 2, provided that when b is 2, the two R 2 are the same or different.

3. The curable composition according to claim 1 , wherein the metal oxide particles of the surface-modified metal oxide particles (A) are silica particles.

4. The curable composition according to claim 1 , wherein a median diameter of the surface-modified metal oxide particles (A) is from 1 to 1,000 nm.

5. The curable composition according to claim 1 , wherein the compound (B) is a fluoro(meth)acrylate.

6. The curable composition according to claim 1 , wherein the compound (C) is

a compound (C1) having a urethane bond and having at least two (meth)acryloyl groups, or

a compound (C2) having —OCH 2 CH(OH)CH 2 — and having at least two (meth)acryloyl groups.

7. The curable composition according to claim 6 , wherein the compound (C) is the compound (C1), which is a compound represented by formula (C11):

{(CH 2 ═CR 11 C(O)O—) i J-OC(O)NH—} k Q  (C11)

where R 11 is a hydrogen atom or a methyl group, i is 1 or 2, J is a (i+1)-valent organic group, and Q is a k-valent organic group.

8. The curable composition according to claim 6 , wherein the compound (C) is the compound (C2), which is a compound represented by formula (C21):

CH 2 ═CR 21 C(O)O—CH 2 CH(OH)CH 2 —(O) s —} t G  (C21)

where R 21 is a hydrogen atom or a methyl group, s is 0 or 1, t is an integer of at least 2, and G is a t-valent organic group.

9. The curable composition according to claim 1 , wherein the compound (D) is

a compound (D1) having no unsaturated bond-containing ring structure and having one (meth)acryloyloxy group, or

a compound (D2) having no unsaturated bond-containing ring structure and having at least two (meth)acryloyloxy groups.

10. The curable composition according to claim 9 , wherein the compound (D) is the compound (D1), which is an acrylic acid ester or a methacrylic acid ester.

11. The curable composition according to claim 9 , wherein the compound (D) is the compound (D2), which is a (meth)acrylate of a diol, a (meth)acrylate of a triol, or a tetraol (meth)acrylate.

12. The curable composition according to claim 1 , wherein the polymerization initiator (E) is a photo-radical polymerization initiator.

13. The curable composition according to claim 1 , further comprising

a solvent containing at least one member selected from the group consisting of an ester, a ketone, a hydroxyl group, and an ether.

14. The curable composition according to claim 1 , which has a viscosity at 25° C. of from 100 to 15,000 mPa·s.

15. A cured product, obtained by a process comprising

curing the curable composition according to claim 1 .

16. The curable composition according to claim 1 , wherein a proportion of said particles (A) ranges from 27.1 to 43.1 mass % per 100 mass % of the total mass of said particles (A), said component (B), said component (C), and said component (D).

17. The curable composition according to claim 1 , wherein a proportion of said compound (B) ranges from 1.7 to 9.4 mass % per 100 mass % of the total mass of said particles (A), said component (B), said component (C), and said component (D).

18. The curable composition according to claim 1 , wherein a proportion of said compound (C) ranges from 11.6 to 45.3 mass % per 100 mass % of the total mass of said particles (A), said component (B), said component (C), and said component (D).

19. The curable composition according to claim 1 , wherein a proportion of said compound (D) ranges from 24.7 to 49.6 mass % per 100 mass % of the total mass of said particles (A), said component (B), said component (C), and said component (D).

20. The curable composition according to claim 1 , wherein said compound (D) has an alicylic structure.

21. The curable composition according to claim 1 , wherein compound (C) does not contain a compound having a urethane bond.