Liquid crystal optical element and method for its production

1. A method for producing a liquid crystal optical element, which comprises:

sandwiching a mixture of a liquid crystal with an uncured curable composition between a pair of substrates which are provided with transparent electrodes and of which at least one is transparent, and

curing the curable composition to form a liquid crystal/cured composite layer,

wherein the curable composition comprises a compound of the formula (1):

A 1 -(OR 1 ) n —O-Z-O—(R 2 O) m -A 2   Formula (1)

wherein each of A 1 and A 2 independently of each other, is an acryloyl group, a methacryloyl group, a glycidyl group or an allyl group; each of R 1 and R 2 independently of each other, is a C 2-6 alkylene group; Z is a bivalent mesogen structure; and each of n and m independently of each other, is an integer of from 1 to 10,

wherein the curable composition comprises a curable compound having a mesogen structural portion and a curable compound having no mesogen structural portion.

2. The method for producing a liquid crystal optical element according to claim 1 , wherein Z is a 4,4′-biphenylene group, or a 4,4-biphenylene group having part or all of hydrogen substituted by C 1-2 alkyl or halogen atoms.

3. The method for producing a liquid crystal optical element according to claim 1 , wherein each of R 1 and R 2 which are independent of each other, is an ethylene group or a propylene group.

4. The method for producing a liquid crystal optical element according to claim 1 , wherein each of A 1 and A 2 which are independent of each other, is an acryloyl group or a methacryloyl group.

5. The method for producing a liquid crystal optical element according to claim 1 , wherein each of n and m which are independent of each other, is from 1 to 4.

6. The method for producing a liquid crystal optical element according to claim 1 , wherein the curable composition comprises two different curable compounds, of which the molecular weights are different by at least two times.

7. The method for producing a liquid crystal optical element according to claim 6 , wherein the two different curable compounds have curable sites that can be bonded to each other.

8. The method for producing a liquid crystal optical element according to claim 6 , which contains a curable compound having a molecular weight of at least 1,000.

9. The method for producing a liquid crystal optical element according to claim 1 , wherein the mixture further comprises a chiral agent.

10. The method for producing a liquid crystal optical element according to claim 1 , wherein the mixture further comprises a chiral agent, and the helical pitch of the chiral agent is at least 4 μm and at most three times of the electrode gap.

11. The method for producing a liquid crystal optical element according to claim 10 , wherein the electrode gap is from 4 to 50 μm.

12. The method for producing a liquid crystal optical element according to claim 10 , wherein the helical pitch is at least 5 μm and at most two times of the electrode gap.

13. The method for producing a liquid crystal optical element according to claim 1 , wherein the mixture comprises from 1 to 10 wt. % of a curing catalyst.

14. The method for producing a liquid crystal optical element according to claim 1 , wherein a plurality of compounds of the formula (1) wherein n and m are different are present in the curable composition.

15. A liquid crystal optical element produced by the method as defined in claim 1 .