Polymerizable liquid crystal composition, optical anisotropic material, optical element and optical head device

1. A polymerizable liquid crystal composition containing a polymerizable compound having a mesogen structure comprising the following condensed benzene ring group (A) and the following 6-membered cyclic group (B) bonded to at least one bond in the group (A) directly or via a connecting group —OCO— or —COO—, and a monovalent terminal group bonded to each of both terminals of the mesogen structure, at least one of the terminal groups being a monovalent organic group having a polymerizable moiety, where

the condensed benzene ring group (A) is a naphthalenediyl group having bonds at 1-position and at 4- or 5-position, or an anthracenediyl group having bonds at 1- or 9-position and at 4-, 5- or 10-position; and

the 6-membered cyclic group (B) is a 1,4-phenylene group, a trans-1,4-cyclohexylene group or a bivalent group having at least two groups selected from these groups bonded directly or via a connecting group,

wherein the polymerizable compound is represented by the following formula (1):

CH 2 ═CR 1 —COO-J 1 -(E 1 -J 2 ) n -W 1 -J 3 -M-R 2   (1)

where R 1 , R 2 , n, J 1 , J 2 , J 3 , E 1 , W 1 and M are as follows:

R 1 : a hydrogen atom or a methyl group,

R 2 : a C 2-8 alkyl group,

n: 0 or 1,

J 1 : a single bond, —(CH 2 ) a — or —(CH 2 ) b O— (wherein each of “a” and “b” which are independent of each other, is an integer of from 2 to 8),

J 2 , J 3 : each independently a single bond, —OCO— or —COO—,

E 1 : a 1,4-phenylene group or a trans-1,4-cyclohexylene group, provided that a hydrogen atom in such a group may be substituted by a chlorine atom, a fluorine atom, a methyl group or a cyano group,

W 1 : a naphthalene-1,4-diyl group, a naphthalene-1,5-diyl group, an anthracene-1,4-diyl group, an anthracene-1,5-diyl group, an anthracene-1,10-diyl group, an anthracene-4,9-diyl group, an anthracene-5,9-diyl group or an anthracene-9,10-diyl group, provided that a hydrogen atom in such a group may be substituted by a chlorine atom, a fluorine atom, a methyl group or a cyano group, and

M: a group selected from groups represented by the following formulae (a) to (f):

2. The polymerizable liquid crystal composition according to claim 1 , wherein M is a group selected from groups represented by the following formulae (a) to (e):

3. The polymerizable liquid crystal composition according to claim 2 , wherein M is a trans-1,4-cyclohexylene group or a trans,trans-4,4′-bicyclohexylene group.

4. The polymerizable liquid crystal composition according to claim 1 , which further contains a polymerizable compound represented by the following formula (2):

CH 2 ═CR 3 —COO-J 4 -E 2 -COO—W 2 —OCO-E 3 -J 5 -OCO—CR 3 ═CH 2   (2)

wherein R 3 , J 4 , J 5 , E 2 , E 3 , and W 2 are as follows:

R 3 : a hydrogen atom or a methyl group,

J 4 : —(CH 2 ) t O— or —(CH 2 ) u O—CO— (wherein each of “t” and “u” which are independent of each other, is an integer of from 2 to 6),

J 5 : —O(CH 2 ) c — or —COO—(CH 2 ) d — (wherein each of “c” and “d” which are independent of each other, is an integer of from 2 to 6)

E 2 , E 3 : each independently a 1,4-phenylene group or a trans-1,4-cyclohexylene group, provided that a hydrogen atom in such a group may be substituted by a chlorine atom, a fluorine atom, a methyl group or a cyano group, and

W 2 : a naphthalene-1,4-diyl group, a naphthalene-1,5-diyl group, an anthracene-1,4-diyl group, an anthracene-1,5-diyl group, an anthracene-1,10-diyl group, an anthracene-4,9-diyl group, an anthracene-5,9-diyl group or an anthracene-9,10-diyl group, provided that a hydrogen atom in such a group may be substituted by a chlorine atom, a fluorine atom, a methyl group or a cyano group.

5. The polymerizable liquid crystal composition according to claim 1 , wherein the content of the polymerizable compound represented by the formula (1) is at least 10 mass % based on the polymerizable liquid crystal composition.

6. An optical anisotropic material comprising a polymerized composition of claim 1 the polymerizable liquid crystal composition as defined in claim 1 .

7. The optical anisotropic material according to claim 6 , which is optically uniaxial and of which the value of refractive index anisotropy Δn which is a difference between the ordinary refractive index n o and the extraordinary refractive index n e increases as the wavelength of light to be used increases.

8. An optical element to control polarization state and/or phase state of light to be used, comprising the optical anisotropic material as defined in claim 6 .

9. A phase plate, comprising the optical anisotropic material as defined in claim 6 .

10. A polarizing diffraction element having a diffraction grating region to diffract incident light, wherein the diffraction grating region comprises a first member made of a first material and a second member made of a second material, the first member and the second member differ from each other in the refractive index to at least one polarized light, and the first member and the second member are disposed alternately to be in contact with each other; and the first material is the optical anisotropic material as defined in claim 6 .

11. An optical head device comprising a semiconductor laser, an objective lens and a photodetector, and a phase plate and/or a polarizing diffraction element disposed between the objective lens and the photodetector, wherein the phase plate is the phase plate as defined in claim 9 .

12. An optical head device comprising a semiconductor laser, an objective lens and a photodetector, and a phase plate and/or a polarizing diffraction element disposed between the objective lens and the photodetector, wherein the polarizing diffraction element is the polarizing diffraction element as defined in claim 10 .

13. A polymerizable compound represented by the following formula (1):

CH 2 ═CR 1 —COO-J 1 -(E 1 -J 2 ) n -W 1 -J 3 -M-R 2   (1)

wherein R 1 , R 2 , n, J 1 , J 2 , J 3 , E 1 , W 1 and M are as follows:

R 1 : a hydrogen atom or a methyl group,

R 2 : a C 2-8 alkyl group,

n: 0 or 1,

J 1 : a single bond, —(CH 2 ) a — or —(CH 2 ) b O— (wherein each of “a” and “b” which are independent of each other, is an integer of from 2 to 8),

J 2 , J 3 : each independently a single bond, —OCO— or —COO—,

E 1 : a 1,4-phenylene group or a trans-1,4-cyclohexylene group, provided that a hydrogen atom in such a group may be substituted by a chlorine atom, a fluorine atom, a methyl group or a cyano group,

W 1 : a naphthalene-1,4-diyl group, a naphthalene-1,5-diyl group, an anthracene-1,4-diyl group, an anthracene-1,5-diyl group, an anthracene-1,10-diyl group, an anthracene-4,9-diyl group, an anthracene-5,9-diyl group or an anthracene-9,10-diyl group, provided that a hydrogen atom in such a group may be substituted by a chlorine atom, a fluorine atom, a methyl group or a cyano group, and

M: a group selected from groups represented by the following formulae (a) to (f):

14. The polymerizable liquid crystal composition according to claim 4 , wherein a sum of the content of the polymerizable compound represented by the formula (1) and the content of the polymerizable compound represented by the formula (2) is at least 10 mass % based on the polymerizable liquid crystal composition.