JP7517327B2 - Polymer composition and single-layer retardation material - Google Patents

Description

The present invention relates to a composition containing a polymer and a single-layer retardation material. More specifically, the present invention relates to a material having optical properties suitable for applications such as display devices and recording materials, in particular, a liquid crystal polymer suitable for use in optical compensation films such as polarizing plates and retardation plates for liquid crystal displays, a composition containing the polymer, and a single-layer retardation material obtained from the composition.

Due to demands for improved display quality and weight reduction in liquid crystal display devices, there is an increasing demand for polymer films with controlled internal molecular orientation structures as optical compensation films such as polarizing plates and retardation plates. To meet this demand, films that utilize the optical anisotropy of polymerizable liquid crystal compounds have been developed. The polymerizable liquid crystal compounds used here are generally liquid crystal compounds that have a polymerizable group and a liquid crystal structural portion (a structural portion having a spacer portion and a mesogen portion), and acrylic groups are widely used as the polymerizable group.

Such polymerizable liquid crystal compounds are generally made into polymers (films) by irradiating them with ultraviolet or other radiation to polymerize them. For example, a method is known in which a specific polymerizable liquid crystal compound having an acrylic group is supported between supports, and this compound is irradiated with radiation while being maintained in a liquid crystal state to obtain a polymer (Patent Document 1), and a method is known in which a photopolymerization initiator is added to a mixture of two types of polymerizable liquid crystal compounds having an acrylic group or a composition in which this mixture is mixed with chiral liquid crystal, and then ultraviolet light is irradiated to obtain a polymer (Patent Document 2).

In addition, various single-layer coating-type alignment films have been reported, such as alignment films using polymerizable liquid crystal compounds or polymers that do not require a liquid crystal alignment film (Patent Documents 3 and 4), and alignment films using polymers containing photocrosslinking sites (Patent Documents 5 and 6). However, the above film production process has problems such as difficulty, the need to use solvents with excellent dissolving power such as NMP, chloroform, and chlorobenzene as the solvent for the polymer used, and low solubility of the polymer, and no material that solves these problems has been found so far.

Japanese Unexamined Patent Publication No. 62-70407 Japanese Patent Application Publication No. 9-208957 EP 1 090 325 A1 International Publication No. 2008/031243 JP 2008-164925 A Japanese Patent Application Publication No. 11-189665

The present invention has been made in consideration of the above problems, and aims to provide a new polymer that enables the production of a single-layer retardation material with a high retardation value through a simpler process, a composition containing the polymer, and a single-layer retardation material obtained from the composition.

As a result of extensive research into solving the above problems, the inventors discovered that by using a composition containing a specific polymer and a specific additive, a single-layer retardation material with high refractive index anisotropy (Δn) can be obtained without using a liquid crystal alignment film, and further that it is possible to produce a single-layer retardation material with a high retardation value and no turbidity, thereby completing the present invention.

（式中、Ｒ¹は、炭素数１～３０のアルキレン基であり、該アルキレン基の１つ又は複数の水素原子が、フッ素原子又は有機基で置換されていてもよい。また、Ｒ¹中の－ＣＨ₂ＣＨ₂－が、－ＣＨ＝ＣＨ－で置換されていてもよく、Ｒ¹中の－ＣＨ₂－が、－Ｏ－、－ＮＨ－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）－ＮＨ－、－Ｃ（＝Ｏ）－Ｏ－、－Ｏ－Ｃ（＝Ｏ）－、－ＮＨ－、－ＮＨ－Ｃ（＝Ｏ）－ＮＨ－及び－Ｃ（＝Ｏ）－からなる群から選ばれる基で置換されていてもよい。ただし、隣接する－ＣＨ₂－が同時にこれらの基で置換されることはない。また、－ＣＨ₂－は、Ｒ¹中の末端の－ＣＨ₂－であってもよい。
Ｒ²は、２価の芳香族基、２価の脂環族基、２価の複素環式基又は２価の縮合環式基である。
Ｒ³は、単結合、－Ｏ－、－Ｃ（＝Ｏ）－Ｏ－、－Ｏ－Ｃ（＝Ｏ）－又は－ＣＨ＝ＣＨ－Ｃ（＝Ｏ）－Ｏ－である。
Ｒ⁴は、１，４－フェニレン基又はトランス－１，４－シクロヘキシレン基である。
Ｒは、炭素数１～６のアルキル基、炭素数１～６のハロアルキル基、炭素数１～６のアルコキシ基、炭素数１～６のハロアルコキシ基、シアノ基又はニトロ基であり、ｃ≧２のとき、各Ｒは、互いに同一であってもよく、異なっていてもよい。
式（ｂ）中のベンゼン環は、炭素数１～６のアルキル基、炭素数１～６のハロアルキル基、炭素数１～６のアルコキシ基、炭素数１～６のハロアルコキシ基、シアノ基及びニトロ基から選ばれる置換基で置換されていてもよい。
ａは、０、１又は２である。
ｂは、０又は１である。
ｃは、０≦ｃ≦２ｂ＋４を満たす整数である。
破線は、結合手である。）
２．上記光反応性部位を有する側鎖が、下記式（ａ１）で表されるものである１の重合体組成物。

（式中、Ｒ¹、Ｒ²及びａは、上記と同じ。
Ｒ^3Aは、単結合、－Ｏ－、－Ｃ（＝Ｏ）－Ｏ－又は－Ｏ－Ｃ（＝Ｏ）－である。
式（ａ１）中のベンゼン環は、炭素数１～６のアルキル基、炭素数１～６のハロアルキル基、炭素数１～６のアルコキシ基、炭素数１～６のハロアルコキシ基、シアノ基及びニトロ基から選ばれる置換基で置換されていてもよい。
破線は、結合手である。）
３．（Ａ）側鎖型重合体が、更に、液晶性のみを発現する側鎖を有する１又は２の重合体組成物。
４．上記液晶性のみを発現する側鎖が、下記式（１）～（１２）のいずれかで表される液晶性側鎖である３の重合体組成物。

（式中、Ａ¹、Ａ²はそれぞれ独立に、単結合、－Ｏ－、－ＣＨ₂－、－Ｃ（＝Ｏ）－Ｏ－、－Ｏ－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）－ＮＨ－、－ＮＨ－Ｃ（＝Ｏ）－、－ＣＨ＝ＣＨ－Ｃ（＝Ｏ）－Ｏ－又は－Ｏ－Ｃ（＝Ｏ）－ＣＨ＝ＣＨ－である。
Ｒ¹¹は、－ＮＯ₂、－ＣＮ、ハロゲン原子、フェニル基、ナフチル基、ビフェニリル基、フラニル基、１価窒素含有複素環基、炭素数５～８の１価脂環式炭化水素基、炭素数１～１２のアルキル基又は炭素数１～１２のアルキルオキシ基である。
Ｒ¹²は、フェニル基、ナフチル基、ビフェニリル基、フラニル基、１価窒素含有複素環基、炭素数５～８の１価脂環式炭化水素基、及びこれらを組み合わせて得られる基からなる群から選ばれる基であり、これらに結合する水素原子が、－ＮＯ₂、－ＣＮ、ハロゲン原子、炭素数１～５のアルキル基又は炭素数１～５のアルコキシ基で置換されてもよい。
Ｒ¹³は、水素原子、－ＮＯ₂、－ＣＮ、－ＣＨ＝Ｃ（ＣＮ）₂、－ＣＨ＝ＣＨ－ＣＮ、ハロゲン原子、フェニル基、ナフチル基、ビフェニリル基、フラニル基、１価窒素含有複素環基、炭素数５～８の１価脂環式炭化水素基、炭素数１～１２のアルキル基又は炭素数１～１２のアルコキシ基である。
Ｅは、－Ｃ（＝Ｏ）－Ｏ－又は－Ｏ－Ｃ（＝Ｏ）－である。
ｄは、１～１２の整数である。
ｋ１～ｋ５は、それぞれ独立に、０～２の整数であるが、ｋ１～ｋ５の合計は２以上である。
ｋ６及びｋ７は、それぞれ独立に、０～２の整数であるが、ｋ６及びｋ７の合計は１以上である。
ｍ１、ｍ２及びｍ３は、それぞれ独立に、１～３の整数である。
ｎは、０又は１である。
Ｚ¹及びＺ²は、それぞれ独立に、単結合、－Ｃ（＝Ｏ）－、－ＣＨ₂Ｏ－、－ＣＨ＝Ｎ－又は－ＣＦ₂－である。
破線は、結合手である。）
５．上記液晶性のみを発現する側鎖が、式（１）～（１１）のいずれかで表される液晶性側鎖である４の重合体組成物。
６．（Ｉ）１～５のいずれかの重合体組成物を、基板上に塗布して塗膜を形成する工程、
（ＩＩ）上記塗膜に、偏光した紫外線を照射する工程、及び
（ＩＩＩ）上記紫外線を照射した塗膜を加熱して、位相差材を得る工程
を含む、単層位相差材の製造方法。
７．１～５のいずれかの組成物から得られる単層位相差材。 Therefore, the present invention provides the following polymer composition and single-layer retardation material.
1. A polymer composition comprising: (A) a side chain-type polymer having a side chain having a photoreactive moiety represented by the following formula (a) and a side chain having a moiety represented by the following formula (b); and (B) an organic solvent.

(In the formula, R ¹ is an alkylene group having 1 to 30 carbon atoms, and one or more hydrogen atoms of the alkylene group may be substituted with a fluorine atom or an organic group. Furthermore, -CH ₂ CH ₂ - in R ¹ may be substituted with -CH=CH-, and -CH ₂ - in R ¹ may be substituted with a group selected from the group consisting of -O-, -NH-C(=O)-, -C(=O)-NH-, -C(=O)-O-, -O-C(=O)-, -NH-, -NH-C(=O)-NH- and -C(=O)-. However, adjacent -CH ₂ -'s are not simultaneously substituted with these groups. Furthermore, -CH ₂ - may be a terminal -CH ₂ - in R ¹ .
^R2 is a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group, or a divalent fused cyclic group.
^R3 is a single bond, -O-, -C(=O)-O-, -O-C(=O)- or -CH=CH-C(=O)-O-.
R ⁴ is a 1,4-phenylene group or a trans-1,4-cyclohexylene group.
R is an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group, and when c≧2, each R may be the same as or different from each other.
The benzene ring in formula (b) may be substituted with a substituent selected from an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group, and a nitro group.
a is 0, 1 or 2.
b is 0 or 1.
c is an integer satisfying 0≦c≦2b+4.
The dashed lines represent bonds.)
2. The polymer composition according to 1, wherein the side chain having the photoreactive site is represented by the following formula (a1):

(In the formula, R ¹ , R ² and a are the same as above.
R ^3A is a single bond, —O—, —C(═O)—O— or —O—C(═O)—.
The benzene ring in formula (a1) may be substituted with a substituent selected from an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group, and a nitro group.
The dashed lines represent bonds.)
3. The polymer composition of 1 or 2, wherein the side chain polymer (A) further has a side chain that only exhibits liquid crystallinity.
4. The polymer composition according to 3, wherein the side chain exhibiting only liquid crystallinity is a liquid crystalline side chain represented by any one of the following formulas (1) to (12):

(In the formula, A ¹ and A ² each independently represent a single bond, —O—, —CH ₂ —, —C(═O)—O—, —O—C(═O)—, —C(═O)-NH—, —NH-C(═O)—, —CH═CH-C(═O)-O— or —O—C(═O)-CH═CH-.
R ¹¹ is --NO ₂ , --CN, a halogen atom, a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or an alkyloxy group having 1 to 12 carbon atoms.
R ¹² is a group selected from the group consisting of a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and groups obtained by combining these, and a hydrogen atom bonded to these may be substituted with -NO ₂ , -CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
R ¹³ is a hydrogen atom, --NO ₂ , --CN, --CH═C(CN) ₂ , --CH═CH--CN, a halogen atom, a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
E is -C(=O)-O- or -O-C(=O)-.
and d is an integer from 1 to 12.
k1 to k5 each independently represent an integer of 0 to 2, provided that the total of k1 to k5 is 2 or more.
k6 and k7 each independently represent an integer of 0 to 2, provided that the sum of k6 and k7 is 1 or more.
m1, m2, and m3 each independently represents an integer of 1 to 3.
n is 0 or 1.
Z ¹ and Z ² each independently represents a single bond, --C(═O)--, --CH ₂ O--, --CH═N-- or --CF ₂ --.
The dashed lines represent bonds.)
5. The polymer composition according to 4, wherein the side chain exhibiting only liquid crystallinity is a liquid crystalline side chain represented by any one of formulas (1) to (11).
6. (I) A step of applying any one of the polymer compositions according to 1 to 5 onto a substrate to form a coating film;
(II) a step of irradiating the coating film with polarized ultraviolet light; and (III) a step of heating the coating film irradiated with ultraviolet light to obtain a retardation material.
7. A single-layer retardation material obtained from any one of the compositions 1 to 5.

The present invention makes it possible to provide a single-layer retardation material that has a high retardation value even when it is a thin film, and a polymer that provides it.

As a result of intensive research, the present inventors have obtained the following findings and have completed the present invention.
The polymer composition of the present invention has a photosensitive side-chain polymer (hereinafter, also simply referred to as a side-chain polymer) capable of expressing liquid crystallinity, and the coating film obtained using the polymer composition is a film having a photosensitive side-chain polymer capable of expressing liquid crystallinity. The coating film is subjected to an orientation treatment by polarized light irradiation without rubbing treatment. Then, after the polarized light irradiation, the side-chain polymer film is heated to form a film (hereinafter, also referred to as a single-layer retardation material) to which optical anisotropy has been imparted. At this time, the slight anisotropy expressed by the polarized light irradiation becomes a driving force, and the liquid crystal side-chain polymer itself is efficiently reoriented by self-organization. As a result, a highly efficient orientation treatment is realized as a single-layer retardation material, and a single-layer retardation material to which high optical anisotropy has been imparted can be obtained.

In addition, in the polymer composition of the present invention, the side chain type polymer, which is component (A), contains a side chain having a photo-alignment moiety represented by formula (a) and a side chain represented by formula (b) above, thereby suppressing aggregation of the polymer. As a result, the retardation material obtained from the polymer composition of the present invention exhibits high retardation even in a thin film. Note that these include the inventor's views on the mechanism of the present invention and do not restrict the present invention.

The following describes in detail an embodiment of the present invention.

[Polymer composition]
The polymer composition of the present invention is characterized by comprising (A) a photosensitive side chain polymer that exhibits liquid crystallinity in a predetermined temperature range and (B) an organic solvent.

[(A) Side Chain Polymer]
Component (A) is a photosensitive side chain polymer that exhibits liquid crystallinity within a predetermined temperature range, and has a side chain having a photoreactive moiety represented by the following formula (a) (hereinafter also referred to as side chain a) and a side chain having a moiety represented by the following formula (b) (hereinafter also referred to as side chain b).

In formula (a), R ¹ is an alkylene group having 1 to 30 carbon atoms, and one or more hydrogen atoms of the alkylene group may be substituted with a fluorine atom or an organic group. In addition, -CH ₂ CH ₂ - in R ¹ may be substituted with -CH=CH-, and -CH ₂ - in R ¹ may be substituted with a group selected from the group consisting of -O-, -NH-C(=O)-, -C(=O)-NH-, -C(=O)-O-, -O-C(=O)-, -NH-, -NH-C(=O)-NH- and -C(=O)-. However, adjacent -CH ₂ - are not substituted with these groups at the same time. In addition, -CH ₂ - may be the terminal -CH ₂ - in R ¹ . R ² is a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group, or a divalent fused cyclic group. R ³ is a single bond, -O-, -C(=O)-O-, -O-C(=O)-, or -CH=CH-C(=O)-O-. R is an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group, and when c≧2, each R may be the same as or different from each other. a is 0, 1, or 2. b is 0 or 1. c is an integer satisfying 0≦c≦2b+4. The dashed lines are bonds.

In formula (b), R ¹ , R ² , R ³ and a are the same as above. R ⁴ is a 1,4-phenylene group or a trans-1,4-cyclohexylene group. The benzene ring in formula (b) may be substituted with a substituent selected from an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group and a nitro group. The dashed lines represent bonds.

The alkylene group having 1 to 30 carbon atoms represented by ^R1 may be any of linear, branched, and cyclic, and specific examples thereof include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, and a decane-1,10-diyl group.

Examples of the divalent aromatic group represented by ^R2 include a phenylene group and a biphenylylene group. Examples of the divalent alicyclic group represented by ^{R2 include a cyclohexanediyl group. Examples of the divalent heterocyclic group represented by R2 include} a furandiyl group. Examples of the divalent condensed cyclic group represented by ^R2 include a naphthylene group.

The side chain a is preferably one represented by the following formula (a1) (hereinafter also referred to as side chain a1).

In formula (a1), R ¹ , R ² and a are the same as above. R ^3A is a single bond, -O-, -C(=O)-O- or -O-C(=O)-. The benzene ring in formula (a1) may be substituted with a substituent selected from an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group and a nitro group. The dashed lines represent bonds.

The side chain a1 is preferably, for example, one represented by the following formula (a1-1).

In formula (a1-1), L is a linear or branched alkylene group having 1 to 16 carbon atoms. X is a single bond, -O-, -C(=O)-O-, or -O-C(=O)-.

(A) The side chain type polymer preferably reacts to light in the wavelength range of 250 to 400 nm and exhibits liquid crystallinity in the temperature range of 100 to 300° C. (A) The side chain type polymer preferably has a photosensitive side chain that reacts to light in the wavelength range of 250 to 400 nm.

(A) Side-chain polymers have photosensitive side chains bonded to their main chains, and can undergo crosslinking or isomerization reactions in response to light. The structure of the photosensitive side-chain polymer capable of expressing liquid crystallinity is not particularly limited as long as it satisfies such characteristics, but it is preferable for the side-chain structure to have a rigid mesogen component. When the above-mentioned side-chain polymer is used as a single-layer retardation material, stable optical anisotropy can be obtained.

A more specific example of a structure of a photosensitive side chain type polymer capable of exhibiting liquid crystallinity is preferably a structure having a main chain composed of at least one selected from the group consisting of radical polymerizable groups such as (meth)acrylate, itaconate, fumarate, maleate, α-methylene-γ-butyrolactone, styrene, vinyl, maleimide, norbornene, and siloxane, and a side chain a.

In addition, since the (A) side-chain polymer exhibits liquid crystallinity in the temperature range of 100 to 300°C, it is preferable that it further has a side chain that only exhibits liquid crystallinity (hereinafter also referred to as side chain c). Note that "exhibiting only liquid crystallinity" here means that a polymer having only side chain c does not exhibit photoalignment and only exhibits liquid crystallinity during the production process of the retardation material of the present invention (i.e., steps (I) to (III) described below).

The side chain c is preferably any one of liquid crystalline side chains selected from the group consisting of the following formulae (1) to (12).

In formulas (1) to (12), A ¹ and A ² are each independently a single bond, -O-, -CH ₂ -, -C(═O)-O-, -O-C(═O)-, -C(═O)-NH-, -NH-C(═O)-, -CH=CH-C(═O)-O- or -O-C(═O)-CH=CH-. R ¹¹ is -NO ₂ , -CN, a halogen atom, a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or an alkyloxy group having 1 to 12 carbon atoms. R ¹² is a group selected from the group consisting of a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and a group obtained by combining these groups, and a hydrogen atom bonded to these groups may be substituted with -NO ₂ , -CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ¹³ is a hydrogen atom, -NO ₂ , -CN, -CH=C(CN) ₂ , -CH=CH-CN, a halogen atom, a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. E is -C(=O)-O- or -O-C(=O)-. d is an integer from 1 to 12. Each of k1 to k5 is independently an integer of 0 to 2, but the sum of k1 to k5 is 2 or more. Each of k6 and k7 is independently an integer of 0 to 2, but the sum of k6 and k7 is 1 or more. Each of m1, m2 and m3 is independently an integer of 1 to 3. n is 0 or 1. Each of Z ¹ and Z ² is independently a single bond, -C(=O)-, -CH ₂ O-, -CH=N- or -CF ₂ -. The dashed lines represent bonds.

Of these, side chain c is preferably represented by any of formulas (1) to (11).

The side-chain polymer of component (A) can be obtained by polymerizing a monomer having a structure represented by formula (a), a monomer having a structure represented by formula (b), and, if desired, a monomer having a structure that exhibits only liquid crystallinity.

（式中、Ｒ¹、Ｒ²、Ｒ³、Ｒ、ａ、ｍ及びｎは、上記と同じ。） Examples of the monomer having the structure represented by formula (a) (hereinafter also referred to as monomer M1) include the compound represented by the following formula (M1).

(In the formula, R ¹ , R ² , R ³ , R, a, m and n are the same as above.)

（式中、Ｒ¹、Ｒ²、Ｒ^3A、Ｒ及びａは、上記と同じ。） The monomer M1 is preferably one represented by the following formula (M1A).

(In the formula, R ¹ , R ² , R ^3A , R and a are the same as above.)

（式中、Ｌ及びＸは、上記と同じ。） Among the monomers M1A, those represented by the following formula (M1B) are more preferred.

(In the formula, L and X are the same as above.)

In formulae (M1), (M1A) and (M1B), PL is a polymerizable group represented by any one of the following formulae (PL-1) to (PL-5).

In formulae (PL-1) to (PL-5), ^Q1 , ^Q2 , and ^Q3 are a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, or a linear or branched alkyl group having 1 to 10 carbon atoms substituted with a halogen. The dashed lines represent bonds to ^R1 or L. Some of these monomers are commercially available, and others can be produced from known substances by known production methods.

（式中、ＰＬは、上記と同じ。ｐは、２～９の整数である。） Preferred examples of the monomer M1 include those represented by the following formulae (M1-1) to (M1-5).

(In the formula, PL is the same as above. p is an integer of 2 to 9.)

（式中、ＰＬ、Ｒ¹～Ｒ⁴及びａは、上記と同じ。） Examples of the monomer having the structure represented by formula (b) (hereinafter, also referred to as monomer M2) include the compound represented by the following formula (M2).

(In the formula, PL, R ¹ to R ⁴ and a are the same as above.)

（式中、Ｒ⁴、ＰＬ、Ｌ及びＸは、上記と同じ。） The monomer M2 is preferably one represented by the following formula (M2A).

(In the formula, R ⁴ , PL, L and X are the same as above.)

Some of these monomers are commercially available, and others can be produced from known materials using known manufacturing methods.

A monomer having a structure that only expresses liquid crystallinity (hereinafter also referred to as monomer M3) is a monomer that causes a polymer derived from the monomer to express liquid crystallinity and that can form a mesogenic group in the side chain portion.

The mesogenic group in the side chain may be a group that forms a mesogenic structure by itself, such as biphenyl or phenylbenzoate, or a group that forms a mesogenic structure by hydrogen bonding between side chains, such as benzoic acid. The following structure is preferred as the mesogenic group in the side chain.

More specific examples of monomer M3 include those having a polymerizable group derived from at least one selected from the group consisting of radical polymerizable groups such as hydrocarbons, (meth)acrylates, itaconates, fumarates, maleates, α-methylene-γ-butyrolactone, styrene, vinyl, maleimides, and norbornenes, and siloxanes, and a structure consisting of at least one of formulas (1) to (12). In particular, monomer M3 is preferably one having (meth)acrylate as the polymerizable group, and preferably one having a -COOH terminal at the side chain.

Preferred examples of the monomer M3 include those represented by the following formulae (M3-1) to (M3-9).

（式中、ＰＬ及びｐは、上記と同じ。）

(In the formula, PL and p are the same as above.)

In addition, other monomers can be copolymerized to the extent that the photoreactivity and/or liquid crystallinity is not impaired. Examples of other monomers include industrially available monomers capable of radical polymerization. Specific examples of other monomers include unsaturated carboxylic acids, acrylic acid ester compounds, methacrylic acid ester compounds, maleimide compounds, acrylonitrile, maleic anhydride, styrene compounds, vinyl compounds, etc.

Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, etc.

Examples of acrylic acid ester compounds include methyl acrylate, ethyl acrylate, isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthryl acrylate, anthryl methyl acrylate, phenyl acrylate, 2,2,2-trifluoroethyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, 2-methyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, 8-methyl-8-tricyclodecyl acrylate, 8-ethyl-8-tricyclodecyl acrylate, and the like.

Examples of methacrylic acid ester compounds include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, benzyl methacrylate, naphthyl methacrylate, anthryl methacrylate, anthryl methyl methacrylate, phenyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, 2-methoxyethyl methacrylate, methoxytriethylene glycol methacrylate, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, 3-methoxybutyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-propyl-2-adamantyl methacrylate, 8-methyl-8-tricyclodecyl methacrylate, and 8-ethyl-8-tricyclodecyl methacrylate.

Examples of vinyl compounds include vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, and propyl vinyl ether. Examples of styrene compounds include styrene, 4-methylstyrene, 4-chlorostyrene, and 4-bromostyrene. Examples of maleimide compounds include maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

The content of side chain a in the side chain type polymer of the present invention is preferably 20 to 99.9 mol %, more preferably 30 to 95 mol %, and even more preferably 40 to 90 mol %, from the viewpoint of photoreactivity.

The content of side chain b in the side chain type polymer of the present invention is preferably 0.1 to 80 mol%, more preferably 5 to 70 mol%, and even more preferably 10 to 60 mol%, from the viewpoint of retardation value.

From the viewpoint of photoreactivity, the content of side chain c in the side chain type polymer of the present invention is preferably 80 mol % or less, more preferably 10 to 70 mol %, and even more preferably 20 to 60 mol %.

As described above, the side chain polymer of the present invention may contain other side chains. When the total content of side chains a to c is less than 100 mol %, the content of the other side chains is the remaining portion.

The method for producing the side chain polymer of component (A) is not particularly limited, and a general-purpose method used industrially can be used. Specifically, it can be produced by radical polymerization, cationic polymerization, or anionic polymerization using the vinyl groups of the above-mentioned monomer M1, monomer M2, and optionally monomer M3, and optionally other monomers. Among these, radical polymerization is particularly preferred from the viewpoint of ease of reaction control, etc.

As a polymerization initiator for radical polymerization, known compounds such as radical polymerization initiators (radical thermal polymerization initiators, radical photopolymerization initiators) and reversible addition-fragmentation chain transfer (RAFT) polymerization reagents can be used.

A radical thermal polymerization initiator is a compound that generates radicals when heated above its decomposition temperature. Examples of such radical thermal polymerization initiators include ketone peroxides (methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), diacyl peroxides (acetyl peroxide, benzoyl peroxide, etc.), hydroperoxides (hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, etc.), dialkyl peroxides (di-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, etc.), peroxyketals (dibutylperoxycyclohexane, etc.), alkyl peresters (peroxyneodecanoic acid-tert-butyl ester, peroxypivalic acid-tert-butyl ester, peroxy-2-ethylcyclohexanoic acid-tert-amyl ester, etc.), persulfates (potassium persulfate, sodium persulfate, ammonium persulfate, etc.), and azo compounds (azobisisobutyronitrile, 2,2'-di(2-hydroxyethyl)azobisisobutyronitrile, etc.). The radical thermal polymerization initiator may be used alone or in combination of two or more kinds.

The radical photopolymerization initiator is not particularly limited as long as it is a compound that initiates radical polymerization by irradiation with light. Examples of such radical photopolymerization initiators include benzophenone, Michler's ketone, 4,4'-bis(diethylamino)benzophenone, xanthone, thioxanthone, isopropylxanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, and isopropyl benzoin ether. , isobutyl benzoin ether, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, camphorquinone, benzanthrone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 4-dimethylaminobenzoic acid ethyl, 4-dimethylaminobenzoic acid isoamyl, 4,4'-di(tert-butylperoxycarbonyl) 1,4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, -(2'-methoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-pentyloxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 4-[p-N,N-di(ethoxycarbonylmethyl)]-2,6-di(trichloromethyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(2'-chlorophenyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(4'-methoxyphenyl)-s-triazine, 2-(p-dimethylaminostyryl)benzoxazole, 2-(p-dimethylaminostyryl)benzthiazole, 2-mercaptobenzothiazole, 3,3'-carbonylbis(7-diethylaminocoumarin), 2-(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetrakis(4-ethoxycarbonylphenyl)-1,2'-biimidazole, 2,2'-bis (2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'bis(2,4-dibromophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 3-(2-methyl-2-dimethylaminopropionyl)carbazole, 3,6-bis(2-methyl-2-morpholinopropionyl)-9 -n-Dodecylcarbazole, 1-hydroxycyclohexyl phenyl ketone, bis(5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetra(t-hexylperoxycarbonyl)benzophenone, 3,3'-di(methoxycarbonyl)-4,4'-di(t-butylperoxycarbonyl)benzophenone, Examples of the radical photopolymerization initiator include 3,4'-di(methoxycarbonyl)-4,3'-di(t-butylperoxycarbonyl)benzophenone, 4,4'-di(methoxycarbonyl)-3,3'-di(t-butylperoxycarbonyl)benzophenone, 2-(3-methyl-3H-benzothiazol-2-ylidene)-1-naphthalen-2-yl-ethanone, and 2-(3-methyl-1,3-benzothiazol-2(3H)-ylidene)-1-(2-benzoyl)ethanone. The radical photopolymerization initiator may be used alone or in combination of two or more.

The radical polymerization method is not particularly limited, and emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, bulk polymerization, solution polymerization, etc. can be used.

The organic solvent used in the polymerization reaction is not particularly limited as long as it dissolves the produced polymer. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methyl-ε-caprolactam, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, γ-butyrolactone, isopropyl alcohol, methoxymethyl pentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl ... , ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, 1,4-dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene Examples of the dimethyl ether acetate include propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

The organic solvents may be used alone or in combination of two or more. Furthermore, even if the solvent does not dissolve the polymer produced, it may be mixed with the organic solvents described above to the extent that the polymer produced does not precipitate. In addition, since oxygen in the organic solvent in radical polymerization inhibits the polymerization reaction, it is preferable to use an organic solvent that has been degassed to the greatest extent possible.

The polymerization temperature during radical polymerization can be selected from any temperature between 30 and 150°C, but is preferably in the range of 50 to 100°C. The reaction can be carried out at any concentration, but if the concentration is too low it becomes difficult to obtain a high molecular weight polymer, and if the concentration is too high the viscosity of the reaction solution becomes too high, making uniform stirring difficult, so the monomer concentration is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration at the beginning, and then an organic solvent can be added.

In the above-mentioned radical polymerization reaction, if the ratio of the radical polymerization initiator to the monomer is high, the molecular weight of the resulting polymer will be small, and if the ratio is low, the molecular weight of the resulting polymer will be large, so the ratio of the radical initiator to the monomer to be polymerized is preferably 0.1 to 10 mol %. In addition, various monomer components, solvents, initiators, etc. can also be added during polymerization.

To recover the polymers produced from the reaction solution obtained by the above reaction, the reaction solution may be poured into a poor solvent to precipitate the polymers. Examples of poor solvents used for precipitation include methanol, acetone, hexane, heptane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, diethyl ether, methyl ethyl ether, and water. The polymer precipitated by pouring into the poor solvent can be recovered by filtration, and then dried at room temperature or by heating under normal or reduced pressure. In addition, the recovered polymer can be redissolved in an organic solvent and the reprecipitation recovery operation can be repeated 2 to 10 times to reduce the amount of impurities in the polymer. Examples of poor solvents in this case include alcohols, ketones, and hydrocarbons. It is preferable to use three or more poor solvents selected from these because this further increases the efficiency of purification.

Taking into consideration the strength of the resulting coating film, the workability during coating film formation, and the uniformity of the coating film, the side chain polymer (A) of the present invention preferably has a weight average molecular weight, as measured by GPC (Gel Permeation Chromatography) method, of 2,000 to 2,000,000, more preferably 2,000 to 1,000,000, and even more preferably 5,000 to 200,000.

[(B) Organic Solvent]
The organic solvent of the component (B) is not particularly limited as long as it is an organic solvent that dissolves the polymer component. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methyl-ε-caprolactam, 2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 1,3-dimethyl-2-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4- Examples of such olefins include hydroxy-4-methyl-2-pentanone, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, and tripropylene glycol methyl ether. These olefins may be used alone or in combination of two or more.

[Other ingredients]
The polymer composition of the present invention may contain a component other than the components (A) and (B). Examples of the component include, but are not limited to, a solvent or a compound that improves the film thickness uniformity and surface smoothness when the polymer composition is applied, and a compound that improves the adhesion between the retardation material and the substrate.

Specific examples of solvents (poor solvents) that improve the uniformity of the film thickness and the surface smoothness include isopropyl alcohol, methoxymethyl pentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, and propylene glycol-tert-butyl ether. t-Butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutyl ether ethanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, 1-hexanol, n-hexane, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, 3-methoxypropionate Examples of solvents having low surface tension include ethyl ether, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-propyl methoxypropionate, 3-butyl methoxypropionate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, and 2-(2-ethoxypropoxy)propanol.

These poor solvents may be used alone or in combination of two or more. When using the poor solvent, its content in the solvent is preferably 5 to 80% by mass, more preferably 20 to 60% by mass, so as not to significantly reduce the solubility of the entire solvent contained in the polymer composition.

Compounds that improve the film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. Specific examples of these include EFTOP (registered trademark) 301, EF303, and EF352 (manufactured by Tochem Products), Megafac (registered trademark) F171, F173, and R-30 (manufactured by DIC), Fluorad FC430 and FC431 (manufactured by 3M), Asahiguard (registered trademark) AG710 (manufactured by AGC), Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by AGC Seimi Chemical Co., Ltd.). The content of these surfactants is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of component (A).

Specific examples of compounds that improve the adhesion between the phase difference material and the substrate include functional silane-containing compounds, and specific examples thereof include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethy Examples of the silylsilane include lenthriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, and N-bis(oxyethylene)-3-aminopropyltriethoxysilane.

Furthermore, in addition to improving the adhesion between the substrate and the retardation material, a phenoplast-based compound or an epoxy group-containing compound may be added to the polymer composition to prevent deterioration of characteristics due to backlight when a polarizing plate is constructed.

Specific examples of phenoplast additives are shown below, but are not limited to these.

Specific examples of epoxy group-containing compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane.

When a compound that improves adhesion to the substrate is used, the content is preferably 0.1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the polymer composition. If the content is less than 0.1 part by mass, the effect of improving adhesion cannot be expected, and if it is more than 30 parts by mass, the alignment of the liquid crystal may deteriorate.

A photosensitizer can also be used as an additive. As the photosensitizer, a colorless sensitizer and a triplet sensitizer are preferred.

Photosensitizers include aromatic nitro compounds, coumarins (7-diethylamino-4-methylcoumarin, 7-hydroxy-4-methylcoumarin), ketocoumarins, carbonyl biscoumarins, aromatic 2-hydroxyketones, aromatic 2-hydroxyketones (2-hydroxybenzophenone, mono- or di-p-(dimethylamino)-2-hydroxybenzophenone, etc.), acetophenone, anthraquinone, xanthone, thioxanthone, benzanthrone, thiazoline (2-benzoylmethylene-3-methyl-β-naphthothiazoline, 2-(β-naphthoylmethylene)-3-methylbenzothiazoline, 2-(α-naphthoylmethylene)-3-methylbenzothiazoline, 2-(4-biphenoylmethylene)-3-methylbenzothiazoline, 2-(β-naphthoylmethylene)-3-methyl-β-naphthothiazoline, 2-(4-biphenoylmethylene)-3-methyl-β-naphthothiazoline, 2-(p-fluorobenzoylmethylene)-3-methyl-β-naphthothiazoline, etc.), oxazoline (2-benzoylmethylene-3-methyl-β-naphthoxazoline, 2-(β-naphthoylmethylene)-3-methylbenzoxazoline, 2-(α-naphthoylmethylene)-3-methylbenzoxazoline, 2-(4-biphenoylmethylene)-3-methylbenzoxazoline, 2-(β-naphthoylmethylene)-3-methyl-β-naphthoxazoline, 2-(4-biphenoylmethylene)-3-methyl-β-naphthoxazoline, 2-(p-fluorobenzoylmethylene)-3-methyl-β-naphthoxazoline, etc.), benzothiazole, nitroaniline (m- or p-nitroaniline, 2,4,6-trinitroaniline, etc.), nitroacenaphthene (5-nitroacenaphthene, etc.), 2-[(m-hydroxy-p-methoxy)styryl]benzothiazole, benzoin alkyl ether, N-alkylated phthalone, acetophenone ketal (2,2-dimethoxyphenylethanone, etc.), naphthalene (2-naphthalenemethanol, 2-naphthalenecarboxylic acid, etc.), anthracene (9-anthracenemethanol, 9-anthracenecarboxylic acid, etc.), benzopyran, azoindolizine, merocoumarin, etc. Among these, aromatic 2-hydroxyketone (benzophenone), coumarin, ketocoumarin, carbonylbiscoumarin, acetophenone, anthraquinone, xanthone, thioxanthone, and acetophenone ketal are preferred.

In addition to the above, the polymer composition of the present invention may contain dielectric or conductive substances for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the phase difference material, and crosslinking compounds for the purpose of increasing the hardness and density of the film when made into a phase difference material, as long as the effects of the present invention are not impaired.

[Preparation of polymer composition]
The polymer composition of the present invention is preferably prepared as a coating solution suitable for forming a single-layer retardation material. That is, the polymer composition used in the present invention is preferably prepared as a solution in which the component (A) and the above-mentioned solvent or compound for improving the film thickness uniformity and surface smoothness, the compound for improving the adhesion between the liquid crystal alignment film and the substrate, etc. are dissolved in the organic solvent of the component (B). Here, the content of the component (A) in the composition of the present invention is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, and particularly preferably 3 to 10% by mass.

The polymer composition of the present invention may contain other polymers in addition to the polymer of component (A) to the extent that the liquid crystal expression ability and photosensitive performance are not impaired. In this case, the content of the other polymers in the polymer component is preferably 0.5 to 80% by mass, more preferably 1 to 50% by mass. Examples of the other polymers include polymers that are not photosensitive side-chain polymers capable of expressing liquid crystallinity, such as poly(meth)acrylate, polyamic acid, and polyimide.

[Single-layer retardation material]
The single-layer retardation material of the present invention can be produced by a method including the following steps (I) to (III).
(I) applying the composition of the present invention onto a substrate to form a coating film;
(II) a step of irradiating the coating film with polarized ultraviolet light, and (III) a step of heating the coating film irradiated with ultraviolet light to obtain a retardation material.

[Step (I)]
Step (I) is a step of applying the composition of the present invention onto a substrate to form a coating film. More specifically, the composition of the present invention is applied onto a substrate (e.g., a silicon/silicon dioxide-coated substrate, a silicon nitride substrate, a substrate coated with a metal (e.g., aluminum, molybdenum, chromium, etc.), a glass substrate, a quartz substrate, an ITO substrate, etc.) or a film (e.g., a resin film such as a triacetyl cellulose (TAC) film, a cycloolefin polymer film, a polyethylene terephthalate film, or an acrylic film) by a method such as bar coating, spin coating, flow coating, roll coating, slit coating, slit coating followed by spin coating, an inkjet method, or a printing method. After application, the solvent is evaporated at 50 to 200°C, preferably 50 to 150°C, by a heating means such as a hot plate, a heat circulation oven, or an IR (infrared) oven to obtain a coating film.

[Step (II)]
In step (II), the coating film obtained in step (I) is irradiated with polarized ultraviolet light. When irradiating the film surface of the coating film with polarized ultraviolet light, the polarized ultraviolet light is irradiated from a certain direction relative to the substrate through a polarizing plate. As the ultraviolet light, ultraviolet light having a wavelength in the range of 100 to 400 nm can be used. Preferably, an optimal wavelength is selected through a filter or the like depending on the type of coating film used. Then, for example, ultraviolet light having a wavelength in the range of 290 to 400 nm can be selected and used so as to selectively induce a photocrosslinking reaction. As the ultraviolet light, for example, light emitted from a high-pressure mercury lamp can be used.

The amount of polarized UV light to be irradiated depends on the coating film used. The amount of irradiation is preferably within the range of 1 to 70%, and more preferably within the range of 1 to 50%, of the amount of polarized UV light that realizes the maximum value of ΔA, which is the difference between the UV absorbance in the direction parallel to the polarization direction of the polarized UV light and the UV absorbance in the direction perpendicular to the polarization direction of the polarized UV light in the coating film.

[Step (III)]
In step (III), the coating film irradiated with the polarized ultraviolet light in step (II) is heated. By heating, it is possible to impart an orientation control ability to the coating film.

Heating can be performed using a heating means such as a hot plate, a heat circulation oven, or an IR (infrared) oven. The heating temperature can be determined taking into consideration the temperature at which the liquid crystallinity of the coating film to be used is expressed.

The heating temperature is preferably within the temperature range at which the polymer of component (A) contained in the composition of the present invention exhibits liquid crystallinity (hereinafter referred to as the liquid crystal appearance temperature). In the case of a thin film surface such as a coating film, the liquid crystal appearance temperature of the coating film surface is expected to be lower than the liquid crystal appearance temperature when the polymer of component (A) is observed in bulk. For this reason, it is more preferable that the heating temperature is within the temperature range of the liquid crystal appearance temperature of the coating film surface. In other words, the temperature range of the heating temperature after irradiation with polarized ultraviolet light is preferably a temperature range with a lower limit of a temperature 10°C lower than the lower limit of the temperature range of the liquid crystal appearance temperature of the polymer of component (A) and an upper limit of a temperature 10°C lower than the upper limit of the liquid crystal temperature range. If the heating temperature is lower than the above temperature range, the effect of amplifying the anisotropy due to heat in the coating film tends to be insufficient, and if the heating temperature is too high, the state of the coating film tends to be close to an isotropic liquid state (isotropic phase), in which case it may be difficult to realign in one direction by self-organization.

The liquid crystal manifestation temperature refers to a temperature that is equal to or higher than the liquid crystal transition temperature at which the polymer or coating surface undergoes a phase transition from a solid phase to a liquid crystal phase, and is equal to or lower than the isotropic phase transition temperature (Tiso) at which the liquid crystal phase undergoes a phase transition from an isotropic phase. For example, manifesting liquid crystallinity at 130°C or lower means that the liquid crystal transition temperature at which the phase transition from a solid phase to a liquid crystal phase occurs is 130°C or lower.

The thickness of the coating film formed after heating can be appropriately selected taking into consideration the step height of the substrate used and the optical and electrical properties, and a thickness of 0.5 to 3 μm, for example, is suitable.

The single-layer retardation material of the present invention obtained in this manner is a material having optical properties suitable for applications such as display devices and recording materials, and is particularly suitable as an optical compensation film such as a polarizing plate and a retardation plate for liquid crystal displays.

The present invention will be explained in more detail below with reference to synthesis examples, examples and comparative examples, but the present invention is not limited to the following examples.

The monomer M1 having a photoreactive group and the monomer M2 having a liquid crystal group used in the examples are shown below. M1 was synthesized according to the synthesis method described in International Publication No. 2011/084546. M2 was synthesized according to the synthesis method described in JP-A-9-118717. M3 was a commercially available product (M6BC, manufactured by Midori Kagaku Co., Ltd.). M4 was synthesized by a known method using 4-phenylcyclohexanone as a raw material. The side chain derived from M1 exhibits photoreactivity and liquid crystallinity, and the side chains derived from M2 to M4 exhibit only liquid crystallinity.

The abbreviations of the reagents used in this example are as follows:
(Organic solvent)
THF: Tetrahydrofuran NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve BCA: Butyl cellosolve acetate PGME: Propylene glycol monomethyl ether

(Polymerization initiator)
AIBN: 2,2'-azobisisobutyronitrile

[1] Synthesis of methacrylate polymer powder [Synthesis Example 1]
M1 (6.6 g, 0.02 mol), M2 (18.4 g, 0.06 mol) and M3 (7.7 g, 0.02 mol) were dissolved in THF (132.7 g) and degassed with a diaphragm pump, then AIBN (0.49 g) was added and degassed again. After this, the mixture was reacted at 60° C. for 8 hours to obtain a methacrylate polymer solution. This polymer solution was dropped into methanol (1,000 mL) and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure to obtain a methacrylate polymer powder P1.

[Synthesis Example 2]
M1 (6.6 g, 0.02 mol), M2 (19.9 g, 0.065 mol) and M3 (5.7 g, 0.015 mol) were dissolved in THF (131.2 g), degassed with a diaphragm pump, and then AIBN (0.49 g) was added and degassed again. After this, the mixture was reacted at 60° C. for 8 hours to obtain a methacrylate polymer solution. This polymer solution was dropped into methanol (1,000 mL), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure to obtain a methacrylate polymer powder P2.

[Synthesis Example 3]
M1 (6.6 g, 0.02 mol), M2 (12.3 g, 0.04 mol) and M4 (15.5 g, 0.04 mol) were dissolved in THF (139.7 g), degassed with a diaphragm pump, and then AIBN (0.49 g) was added and degassed again. After this, the mixture was reacted at 60° C. for 8 hours to obtain a methacrylate polymer solution. This polymer solution was dropped into methanol (1,000 mL), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure to obtain a methacrylate polymer powder P3.

[Synthesis Example 4]
M1 (6.6 g, 0.02 mol) and M2 (24.5 g, 0.08 mol) were dissolved in THF (131.2 g), degassed with a diaphragm pump, and then AIBN (0.49 g) was added and degassed again. After this, the mixture was reacted at 60° C. for 8 hours to obtain a methacrylate polymer solution. This polymer solution was dropped into methanol (1,000 mL), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure to obtain a methacrylate polymer powder P4.

[2] Preparation of polymer solution [Example 1-1]
Methacrylate polymer powder P1 (1.5 g) was added to NMP (3.25 g) and dissolved by stirring at room temperature for 1 hour. PGME (1.5 g), BCS (3.0 g) and BCA (0.75 g) were added to this solution and stirred to obtain polymer solution T1. This polymer solution T1 was used as a retardation material for forming a retardation film as it is.

[Example 1-2]
Methacrylate polymer powder P2 (1.5 g) was added to NMP (3.25 g) and dissolved by stirring at room temperature for 1 hour. PGME (1.5 g), BCS (3.0 g) and BCA (0.75 g) were added to this solution and stirred to obtain polymer solution T2. This polymer solution T2 was used as a retardation material for forming a retardation film as it is.

[Examples 1-3]
Methacrylate polymer powder P3 (1.5 g) was added to NMP (3.25 g) and dissolved by stirring at room temperature for 1 hour. PGME (1.5 g), BCS (3.0 g) and BCA (0.75 g) were added to this solution and stirred to obtain polymer solution T3. This polymer solution T3 was used as a retardation material for forming a retardation film as it is.

[Comparative Example 1]
Methacrylate polymer powder P4 (1.5 g) was added to NMP (3.25 g) and dissolved by stirring at room temperature for 1 hour. PGME (1.5 g), BCS (3.0 g) and BCA (0.75 g) were added to this solution and stirred to obtain polymer solution CT1. This polymer solution CT1 was used as a retardation material for forming a retardation film as it is.

[3] Evaluation of polymer solutions [Examples 2-1 to 2-3, Comparative Examples 2-1 to 2-3]
(1) Preparation of Evaluation Substrate After the polymer solution T1 was filtered through a 0.45 μm filter, it was spin-coated on a glass substrate with a transparent electrode and dried for 90 seconds on a hot plate at 70° C. to form a retardation film with a thickness of 1.0 μm. Next, the coating surface was irradiated with 313 nm ultraviolet light at 10 mJ/cm ² through a polarizing plate and then heated on a hot plate at 180° C. for 20 minutes to prepare a substrate S1 with a retardation film.
Similarly, substrates S2, S3 and CS1 to CS3 with retardation films having predetermined thicknesses were prepared at the baking temperatures shown in Table 1 using the polymer solutions T2, T3 and CT1, respectively.

(2) Retardation Evaluation The retardation values at 550 nm of the substrates S1 to S3 and CS1 to CS3 were evaluated using an AxoScan manufactured by Axometrics, Inc. The results are shown in Table 1.

(3) Haze Evaluation The retardation values at 550 nm of the substrates S1 to S3 and CS1 to CS3 were evaluated using a Haze Meter HZ-V3 manufactured by Suga Test Instruments Co., Ltd. The results are shown in Table 1.

As shown in Table 1, a comparison between the Examples and Comparative Examples shows that the polymer solutions of the Examples show high retardation values even in thin films. Furthermore, an examination of Comparative Examples 2-3 showed a significant decrease in retardation value due to high-temperature baking, which suggests that the high retardation value in thin films is not due to the baking temperature.

Claims (6)

A single-layer retardation material obtained from a polymer composition containing (A) a side chain-type polymer having a side chain having a photoreactive moiety represented by the following formula (a) and a side chain having a moiety represented by the following formula (b), and (B) an organic solvent,
A single-layer retardation material having a film thickness of 0.5 to 3 μm .

(In the formula, R ¹ is an alkylene group having 1 to 30 carbon atoms, and one or more hydrogen atoms of the alkylene group may be substituted with a fluorine atom or an organic group. Furthermore, -CH ₂ CH ₂ - in R ¹ may be substituted with -CH=CH-, and -CH ₂ - in R ¹ may be substituted with a group selected from the group consisting of -O-, -NH-C(=O)-, -C(=O)-NH-, -C(=O)-O-, -O-C(=O)-, -NH-, -NH-C(=O)-NH- and -C(=O)-. However, adjacent -CH ₂ -'s are not simultaneously substituted with these groups. Furthermore, -CH ₂ - may be a terminal -CH ₂ - in R ¹ .
^R2 is a divalent aromatic group, a divalent alicyclic group, a divalent heterocyclic group, or a divalent fused cyclic group.
^R3 is a single bond, -O-, -C(=O)-O-, -O-C(=O)- or -CH=CH-C(=O)-O-.
R ⁴ is a 1,4-phenylene group or a trans-1,4-cyclohexylene group.
R is an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group, and when c≧2, each R may be the same as or different from each other.
The benzene ring in formula (b) may be substituted with a substituent selected from an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group, and a nitro group.
a is 0, 1 or 2.
b is 0 or 1.
c is an integer satisfying 0≦c≦2b+4.
The dashed lines represent bonds.) 2. The single-layer retardation material according to claim 1, wherein the side chain having the photoreactive site is represented by the following formula (a1):

(In the formula, R ¹ , R ² and a are the same as above.
R ^3A is a single bond, —O—, —C(═O)—O— or —O—C(═O)—.
The benzene ring in formula (a1) may be substituted with a substituent selected from an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a haloalkoxy group having 1 to 6 carbon atoms, a cyano group, and a nitro group.
The dashed lines represent bonds.) 3. The single-layer retardation material according to claim 1, wherein the side chain type polymer (A) further has a side chain that exhibits only liquid crystallinity. 4. The single-layer retardation material according to claim 3, wherein the side chain exhibiting only liquid crystallinity is a liquid crystalline side chain represented by any one of the following formulas (1) to (12):

(In the formula, A ¹ and A ² each independently represent a single bond, —O—, —CH ₂ —, —C(═O)—O—, —O—C(═O)—, —C(═O)-NH—, —NH-C(═O)—, —CH═CH-C(═O)-O— or —O—C(═O)-CH═CH-.
R ¹¹ is --NO ₂ , --CN, a halogen atom, a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or an alkyloxy group having 1 to 12 carbon atoms.
R ¹² is a group selected from the group consisting of a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and groups obtained by combining these, and a hydrogen atom bonded to these may be substituted with -NO ₂ , -CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
R ¹³ is a hydrogen atom, --NO ₂ , --CN, --CH═C(CN) ₂ , --CH═CH--CN, a halogen atom, a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.
E is -C(=O)-O- or -O-C(=O)-.
and d is an integer from 1 to 12.
k1 to k5 each independently represent an integer of 0 to 2, provided that the total of k1 to k5 is 2 or more.
k6 and k7 each independently represent an integer of 0 to 2, provided that the sum of k6 and k7 is 1 or more.
m1, m2, and m3 each independently represents an integer of 1 to 3.
n is 0 or 1.
Z ¹ and Z ² each independently represents a single bond, --C(═O)--, --CH ₂ O--, --CH═N-- or --CF ₂ --.
The dashed lines represent bonds.) 5. The single-layer retardation material according to claim 4, wherein the side chain exhibiting only liquid crystallinity is a liquid crystalline side chain represented by any one of formulas (1) to (11). (I) a step of applying a polymer composition containing (A) a side chain type polymer having a side chain having a photoreactive moiety represented by formula (a) and a side chain having a moiety represented by formula (b), and (B) an organic solvent onto a substrate to form a coating film;
The method for producing a single-layer retardation material according to claim 1 , comprising: (II) a step of irradiating the coating film with polarized ultraviolet light; and (III) a step of heating the coating film irradiated with ultraviolet light to obtain a retardation material.