Polymerizable liquid crystal compound, liquid crystal composition, optical anisotropic material and optical element

1. A compound represented by the following formulae (1′), (2) or (3):

CH 2 ═CR 1 —COO-L-E 1 -E 2 -E 3 -R 2   (1′)

provided that the symbols in the formula (1′) have the following meanings:

R 1 is a hydrogen atom or a methyl group;

R 2 is a C 1-8 alkyl group;

L is -Cy-COO— (wherein Cy is a trans-1,4-cyclohexylene group), or -Cy-OCO—; and

E 1 , E 2 , E 3 are each independently a 1,4-phenylene group or a trans-1,4cyclohexylene group (provided that at least one of E 1 , E 2 and E 3 is a trans-1,4-cyclohexylene group, and in a case where L is -Cy-COO—, E 1 is a trans-1,4-cyclohexylene group), provided that the above 1,4-phenylene group and trans-1,4-cyclohexylene group may be such that a hydrogen atom bonded to a carbon atom in each group may be substituted by a fluorine atom, a chlorine atom or a methyl group;

CH 2 ═CR 1 —COO—(CH 2 ) p O-Ph-Cy-Ph-R 2   (2)

provided that the symbols in the formula (2) have the following meanings:

R 1 is a hydrogen atom or a methyl group;

R 2 is a C 1-8 alkyl group;

Ph is a 1,4-phenylene group;

Cy is a trans-1,4-cyclohexlene group; and

p is an integer of from 2 to 8; and

CH 2 ═CR 1 —COO-Ph-Cy-Ph-R 2   (3)

provided that the symbols in the formula (3) have the following meanings:

R 1 is a hydrogen atom or a methyl group;

R 2 is a C 1-8 alkyl group;

Ph is a 1,4-phenylene group; and

Cy is a trans-1,4-cyclohexlene group.

2. A liquid crystal composition, comprising:

(i) at least two compounds selected from the compounds as defined in claim 1 or (ii) at least one compound as defined in claim 1 and at least one polymerizable liquid crystal other than the compound as defined in claim 1 .

3. An optical anisotropic material obtained by polymerizing the liquid crystal composition as defined in claim 2 in a state where the liquid crystal composition shows a liquid crystal phase and in a state where the liquid crystal is aligned.

4. An optical element obtained by sandwiching the liquid crystal composition as defined in claim 2 in a pair of supports, and polymerizing the liquid crystal composition in a state where it shows a liquid crystal phase and in a state where the liquid crystal is aligned.

5. A diffraction element, which comprises the optical element as defined in claim 4 .

6. A phase plate, which comprises the optical element as defined in claim 4 .

7. A polymerizable liquid crystal composition, comprising;

at least 75 mass % of a polymerizable liquid crystal,

wherein the polymerizable liquid crystal composition comprises at least 5 mass % of a compound represented by the following formula (1) based on the entire polymerizable liquid crystal; and

wherein the polymerizable liquid crystal composition comprises at least 50 mass % of a compound represented by the following formula (1) and at least one compound represented by the following formulae (3A), (3B) and (3C) based on the entire polymerizable liquid crystal,

CH 2 ═CR 1 —COO-(L) k -E 1 -E 2 -E 3 -(E 4 ) m -(E 5 ) n -R 2   (1)

CH 2 ═CR 3 —COO-Ph-OCO-Cy-Z 2 -R 4   (3A)

CH 2 ═CR 5 —COO-Z 3 -Z 4 -R 6   (3B)

CH 2 ═CR 7 —COO-(CH 2 ) v —O-Ph-Z 5 -R 8   (3C)

provided that the symbols in the formulae have independently the following meanings;

R 1 , R 3 , R 5 and R 7 are each independently a hydrogen atom or a methyl group;

R 3 , R 4 , R 6 and R 8 are each independently a C 1-8 alkyl group;

L is —(CH 2 ) p O—, —(CH 2 ) q —, -Cy-COO— (Cy is a trans-1,4-cyclohexylene group), -Cy-OCO—, -E 6 -(CH 2 ) 2 —, -E 7 -CH 2 O— or -E 8 -O— (wherein each of p and q which are independent of each other, is an integer of from 2 to 8);

E 1 , E 2 , E 3 , E 4 , E 5 , E 6 , E 7 , E 8 , Z 2 , Z 3 , Z 4 and Z 5 are each independently a 1,4-phenylene group or a trans-1,4-cyclohexylene group (provided that at least one of E 1 , E 2 and E 3 is a trans-1,4-cyclohexylene group, and in case where L is -Cy-OCO—, E 1 is a trans-1,4-cyclohexylene group), provided that the above 1,4-phenylene group and trans-1,4-cyclohexylene group may be such that a hydrogen atom bonded to a carbon atom in each group may be substituted by a fluorine atom, a chlorine atom or a methyl group; and

k, m, n are each independently 0 or 1, provided that when k is 1 and L is -Cy-COO—, -Cy-OCO—, -E 6 -(CH 2 ) 2 —, -E 7 -CH 2 O— or -E 8 -O—, at least one of m and n is 0;

Ph is a 1,4-phenylene group; and

v is an integer of from 1 to 8.

8. The polymerizable liquid crystal composition according to claim 7 , wherein the compound represented by said formula (1) is a compound represented by the following formula (1B):

CH 2 ═CR 1 —COO-E 1 -E 2 -E 3 -R 2   (1B)

provided that the symbols in the formulae have the same meanings as above.

9. The polymerizable liquid crystal composition according to claim 8 , wherein the compound represented by said formula (1B) is a compound represented by the following formula (1Ba) or (1Bb):

CH 2 ═CR 1 —COO-Ph-Cy-Ph-R 2   (1Ba)

CH 2 ═CR 1 —COO-Ph-Ph-Cy-R 2   (1Bb)

provided that the symbols in the formulae have the same meanings as above.

10. An optical anisotropic material obtained by polymerizing the liquid crystal composition as defined in claim 7 in a state where the liquid crystal composition shows a liquid crystal phase and in a state where the liquid crystal is aligned.

11. An optical element obtained by sandwiching the liquid crystal composition as defined in claim 7 in a pair of supports, and polymerizing the liquid crystal composition in a state where it shows a liquid crystal phase and in a state where the liquid crystal is aligned.

12. A diffraction element, which comprises the optical element as defined in claim 11 .

13. A phase plate, which comprises the optical element as defined in claim 7 .