WO2024071364A1

WO2024071364A1 - Polymer composition and single-layer retardation material

Info

Publication number: WO2024071364A1
Application number: PCT/JP2023/035570
Authority: WO
Inventors: 友基玉井; 隆之根木
Original assignee: 日産化学株式会社
Priority date: 2022-09-29
Filing date: 2023-09-29
Publication date: 2024-04-04

Abstract

Provided is a polymer composition from which a retardation film reduced in turbidity can be produced by a simpler process. The polymer composition comprises: (A) a block copolymer comprising a photosensitive side-chain-type polymer block (A1) capable of exhibiting liquid crystallinity and a polymer block (A2) made up of repeating units containing neither a photo-aligning side chain nor a liquid-crystalline side chain; and (B) an organic solvent.

Description

Polymer composition and single-layer retardation material

The present invention relates to a composition containing a polymer and a single-layer retardation material.

The demand for improved display quality and lighter weight for liquid crystal display devices has led to an increased 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 are being 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 commonly used as the polymerizable group.

Such polymerizable liquid crystal compounds are generally made into polymers (films) by polymerizing them through exposure to radiation such as ultraviolet light. 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 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).

Also, 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). Polymers that exhibit high alignment have low solubility, and as a retardation material, problems such as haze and insufficient retardation occur. Until now, no material that solves these problems has been found.

Japanese Patent Application Laid-Open No. 62-70407 Japanese Patent Application Laid-Open No. 9-208957 European Patent Application Publication No. 1090325 International Publication No. 2008/031243 JP 2008-164925 A Japanese Patent Application Laid-Open No. 11-189665

The present invention has been made in consideration of the above problems, and aims to provide a polymer composition that enables the production of a single-layer retardation material with less turbidity through a simpler process, and a single-layer retardation material obtained from the polymer 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 specific additives, it is possible to produce a single-layer retardation material with low turbidity and anisotropy (Δn) at low temperatures without using a liquid crystal alignment film, and thus completed the present invention.

That is, the present invention provides the following polymer composition and single-layer retardation material.
1. A polymer composition comprising: (A) a block copolymer having (A1) a photosensitive side chain type polymer block capable of exhibiting liquid crystallinity, and (A2) a polymer block consisting of a repeating unit containing neither a photoalignable side chain nor a liquid crystalline side chain; and (B) an organic solvent.
2. The polymer composition according to 1, wherein the side chain type polymer block (A1) has a side chain represented by any one of the following formulas (a1) to (a6):

(In the formula, n1 and n2 each independently represent 0, 1, 2, or 3.
L is a single bond or an alkylene group having 1 to 12 carbon atoms, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
T ¹ is a single bond or an alkylene group having 1 to 12 carbon atoms, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
A ¹ , A ² and D ¹ each independently represent a single bond, -O-, -CH ₂ -, -C(═O)-O-, -O-C(═O)-, -C(═O)-NH- or -NH-C(═O)-, provided that when T ¹ is a single bond, A ² is also a single bond.
^Y1 and ^Y2 are a phenylene group or a naphthylene group, and some or all of the hydrogen atoms of the phenylene group and the naphthylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
P ¹ , Q ¹ and Q ² are each independently a single bond, a phenylene group or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, in which some or all of the hydrogen atoms of the phenylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. When the number of Q ^1s is 2 or more, each Q ¹ may be the same as or different from another, and when the number of Q ^2s is 2 or more, each Q ² may be the same as or different from another.
R is a hydrogen atom, a cyano group, a halogen atom, a carboxy group, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
X ¹ and X ² are each independently a single bond, -O-, -C(=O)-O-, -O-C(=O)-, -N=N-, -CH=CH-, -C≡C-, -CH=CH-C(=O)-O-, or -O-C(=O)-CH=CH-. When the number of X ¹ is 2 or more, each X ¹ may be the same as or different from each other, and when the number of X ² is 2 or more, each X ² may be the same as or different from each other.
Z ^1a and Z ^2a each independently represent a hydrogen atom, a halogen atom, a cyano group or an alkyl group having 1 to 3 carbon atoms, and some or all of the hydrogen atoms of this alkyl group may be substituted with fluorine atoms.
Cou is a coumarin-6-yl group or a coumarin-7-yl group, and some of the hydrogen atoms bonded to these may be substituted with _-NO2 , -CN, -CH=C(CN) ₂ , -CH=CH-CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
E is -C(=O)-O-, -OC(=O)-, -C(=O)-S- or -SC(=O)-.
G ¹ and G ² are each independently N or CH.
The dashed lines represent bonds.)
3. The polymer composition of 1 or 2, wherein the side chain type polymer block (A1) further has a side chain that is not photodimerized or photoisomerized.
4. The polymer composition according to 3, wherein the side chain which is neither photodimerized nor photoisomerized is represented by any one of the following formulas (b1) to (b13):

(In the formula, ^A3 and ^A4 each independently represent a single bond, -O-, _-CH2- , -C(=O)-O-, -O-C(=O)-, -C(=O)-NH-, or -NH-C(=O)-. When the number of ^A4 's is 2 or more, each ^A4 may be the same or different.
R ¹ 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 alkoxy group having 1 to 12 carbon atoms.
^R2 is a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, or a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with _-NO2 , -CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
^R3 is a hydrogen atom, _-NO2 , -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-, -OC(=O)-, -C(=O)-S- or -SC(=O)-.
a 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 represent a single bond, --C(═O)--, --CH ₂ --O--, or --CF ₂ --.
W ¹ , W ² and W ³ are each independently a single bond, -O-, -C(=O)-O-, -O-C(=O)-, -C(=O)-N(R')- or -N(R')-C(=O)-. When the number of W ² is 2 or more, each W ² may be the same or different. R' represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Q is an alkylene group having 1 to 10 carbon atoms, some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
L represents a single bond, an alkylene group having 1 to 12 carbon atoms, or a divalent linking group in which one or more of the -CH ₂ - constituting the alkylene group having 1 to 12 carbon atoms are replaced with -O-, -S-, -C(═O)-O-, or -O-C(═O)-, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
Q ¹ is a single bond, a phenylene group, a naphthylene group or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group and naphthylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. When the number of Q ¹ is 2 or more, each Q ¹ may be the same or different.
n1 is 0, 1, 2 or 3.
The hydrogen atoms on the benzene ring and the naphthalene ring 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 halogen atom, a cyano group, and a nitro group.
The dashed lines represent bonds.)
5. The polymer composition according to 1, wherein the polymer block (A2) consisting of repeating units containing neither a photoalignable side chain nor a liquid crystalline side chain is a polymer block derived from a polymeric polymerization initiator.
6. The polymer composition according to 5, wherein the polymer type polymerization initiator has a repeating unit represented by the following formula (1):

(In the formula, R ^a1 to R ^a4 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, or a cyano group. R ^L1 and R ^L2 are each independently an alkylene group having 1 to 10 carbon atoms. L ¹ and L ² are each independently -C(=O)-O-, -O-C(=O)-, -C(=O)-NH-, or -NH-C(=O)-. X is a divalent group represented by the following formula (2) or (3).)

(In the formula, R ^a5 to R ^a8 are a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. R ^L3 , R ^L4 , R ^L5 , and R ^L6 are each independently an alkylene group having 1 to 10 carbon atoms. x and y are each independently a positive integer.)
7. The polymer composition according to 6, wherein the polymer type polymerization initiator is represented by any one of the following formulas (In-1) to (In-2):

(In the formula, x and y are the same as above, and n is a positive integer.)
8. The polymer composition according to 1, wherein the polymer block (A2) consisting of repeating units containing neither a photoalignable side chain nor a liquid crystalline side chain is a polymer block derived from a polymeric chain transfer agent.
9. The polymer composition according to 8, wherein the polymeric chain transfer agent is represented by the following formula (4):

(In the formula, Y is a linear or branched alkyl group having 1 to 3 carbon atoms, a ^hydroxyl group, a carboxyl group, or a sulfanyl group. R and ^R are each independently a single bond or a linear or branched alkylene group having 1 to 6 carbon atoms. x is a positive integer.)
10. The polymer composition of 1, wherein the photosensitive side chain type polymer block (A1) capable of exhibiting liquid crystallinity has a number average molecular weight of 5,000 to 300,000.
11. The polymer composition according to 1, wherein the polymer block (A2) consisting of repeating units containing neither a photoalignable side chain nor a liquid crystalline side chain has a number average molecular weight of 200 to 10,000.
12. (I) A step of applying any one of the polymer compositions according to 1 to 11 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.
13. A single-layer retardation material obtained from any one of the polymer compositions 1 to 11.

The present invention provides a single-layer retardation material that is thin but has little turbidity and exhibits retardation even when fired at a low temperature, as well as a polymer composition 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 contains a block copolymer (hereinafter also referred to as a side chain type block copolymer) having a photosensitive side chain type polymer block (A1) (hereinafter also referred to as a side chain type polymer block) capable of expressing liquid crystallinity and a polymer block (A2) consisting of a repeating unit not including a photoalignable side chain and a liquid crystal side chain, and the coating film obtained using the polymer composition is a film having a photosensitive side chain capable of expressing liquid crystallinity. The coating film is not subjected to a rubbing treatment, but is subjected to an orientation treatment by polarized light irradiation. Then, after the polarized light irradiation, the polymer film is heated to become 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 side chain type block copolymer itself is efficiently reoriented by self-organization. As a result, a highly efficient orientation treatment is realized, and a single-layer retardation material to which high optical anisotropy has been imparted can be obtained.

The polymer composition of the present invention is also characterized in that the polymer of component (A) is a block copolymer having a photosensitive side-chain type polymer block capable of expressing liquid crystallinity, and a polymer block (A2) consisting of repeating units that do not contain photoalignable side chains and liquid crystal side chains. This improves the molecular mobility of the side-chain type block copolymer of component (A) in a solvent, and as a result, the molecular crystallinity in the film of the retardation material obtained from the polymer composition of the present invention is suppressed, and visual haze is suppressed. Note that these include the inventor's views on the mechanism of the present invention, and are not restrictive of the present invention.

Hereinafter, embodiments of the present invention will be described in detail.
The polymer composition of the present invention is characterized by comprising: (A) a block copolymer having a side chain-type polymer block (A1) having a side chain having a photoreactive site and a polymer block (A2) composed of a repeating unit containing neither a photoalignable side chain nor a liquid crystalline side chain; and (B) an organic solvent.

[(A) Side Chain Block Copolymer]
The component (A) is a photosensitive side-chain type block copolymer that exhibits liquid crystallinity in a predetermined temperature range, and includes a side-chain type polymer block (A1) having a side chain with a photoreactive site and a polymer block (A2) consisting of a repeating unit that does not have a photoalignable side chain and a liquid crystal side chain. The side-chain type polymer block (A1) has a photoreactive site that reacts with ultraviolet light in the side chain, and specifically includes a photosensitive side chain that can exhibit liquid crystallinity and a liquid crystal side chain as necessary. The polymer block (A2) consisting of a repeating unit that does not have a photoalignable side chain and a liquid crystal side chain may have a main chain derived from a predetermined polymerization initiator described later. A coating film obtained from a polymer composition containing such a side-chain type block copolymer is a film that has liquid crystallinity and photosensitivity due to the side-chain type polymer block (A1), and high solvent solubility and film flexibility (low glass transition point ability) due to the polymer block (A2) consisting of a repeating unit that does not have a photoalignable side chain and a liquid crystal side chain. The coating film is not subjected to a rubbing treatment, but is subjected to an orientation treatment by polarized light irradiation. After the polarized light irradiation, the side-chain polymer film is heated to form a film (single-layer retardation film) with optical anisotropy. At this time, the slight anisotropy generated by the polarized light irradiation becomes a driving force, and the side-chain block copolymer itself is efficiently reoriented by self-organization. As a result, a highly efficient orientation process is realized as a single-layer retardation film, and a single-layer retardation film with high optical anisotropy can be obtained.

In the present invention, photoreactivity refers to the property of causing either (A-1) a photocrosslinking (photodimerization) reaction, (A-2) a photoisomerization reaction, or (A-3) a photo-Fries rearrangement reaction; or a combination of these reactions.

The side chain type block copolymer is (i) a polymer that exhibits liquid crystallinity in a predetermined temperature range and has a photoreactive side chain. The side chain type block copolymer (ii) reacts to light in the wavelength range of 200 to 400 nm, preferably 240 to 400 nm, and exhibits liquid crystallinity in the temperature range of 50 to 300°C. The side chain type block copolymer (iii) preferably has a photoreactive side chain that reacts to light in the wavelength range of 200 to 400 nm, preferably 240 to 400 nm, particularly polarized ultraviolet light. The side chain type block copolymer (iv) preferably has a mesogen group to exhibit liquid crystallinity in the temperature range of 50 to 300°C.

The side chain type block copolymer has a photoreactive side chain having photoreactivity as described above. The structure of the side chain is not particularly limited, but has a structure that causes the above-mentioned (A-1), (A-2) and/or (A-3) reactions, and in particular, has a structure that causes (A-1) photocrosslinking reaction and/or (A-2) photoisomerization reaction. The structure that causes (A-1) photocrosslinking reaction is preferable in that the structure after the reaction can stably maintain the orientation of the side chain type polymer block for a long period of time even if it is exposed to external stress such as heat. In addition, the structure that causes (A-2) photoisomerization reaction is preferable in that it allows orientation treatment with a lower exposure amount compared to photocrosslinking and photofleece transition, and increases production efficiency when manufacturing retardation films.

The side chain structure of the side chain type polymer block preferably has a rigid mesogen component, since this stabilizes the alignment of the liquid crystal. Examples of mesogen components include, but are not limited to, a biphenyl group, a terphenyl group, a phenylcyclohexyl group, a phenylbenzoate group, and the like.

The side chain having a photoreactive site that undergoes a photoreaction with ultraviolet light (hereinafter also referred to as side chain a) contained in the side chain type polymer block is preferably one represented by any of the following formulas (a1) to (a6). From the viewpoint of solubility in a solvent, the number of benzene rings in one side chain a is preferably 3 or less.

In formulae (a1) to (a6), n1 and n2 are each independently 0, 1, 2, or 3. L is a single bond or an alkylene group having 1 to 12 carbon atoms, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms. T ¹ is a single bond or an alkylene group having 1 to 12 carbon atoms, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms. A ¹ , A ² , and D ¹ are each independently a single bond, -O-, -CH ₂ -, -C(═O)-O-, -O-C(═O)-, -C(═O)-NH-, or -NH-C(═O)-. However, when T ¹ is a single bond, A ² is also a single bond. Y ¹ and Y ² are phenylene or naphthylene groups, and some or all of the hydrogen atoms of the phenylene and naphthylene groups may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. P ¹ , Q ¹ , and Q ² are each independently a single bond, a phenylene group, or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. When the number of Q ^1s is 2 or more, each Q ¹ may be the same as or different from each other, and when the number of Q ^2s is 2 or more, each Q ² may be the same as or different from each other. R is a hydrogen atom, a cyano group, a halogen atom, a carboxy group, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. X ¹ and X ² are each independently a single bond, -O-, -C(=O)-O-, -O-C(=O)-, -N=N-, -CH=CH-, -C≡C-, -CH=CH-C(=O)-O-, or -O-C(=O)-CH=CH-. When the number of X ¹ is 2 or more, each X ¹ may be the same or different from each other, and when the number of X ² is 2 or more, each X ² may be the same or different from each other. Z ^1a and Z ^2a are each independently a hydrogen atom, a halogen atom, a cyano group, or an alkyl group having 1 to 3 carbon atoms, and some or all of the hydrogen atoms of this alkyl group may be substituted with fluorine atoms. Cou is a coumarin-6-yl group or a coumarin-7-yl group, and some of the hydrogen atoms bonded to these may be substituted with _-NO2 , -CN, -CH=C(CN) ₂ , -CH=CH-CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. E is -C(=O)-O-, -O-C(=O)-, -C(=O)-S-, or -S-C(=O)-. ^G1 and ^G2 are each independently N or CH. The dashed lines represent bonds.

The alkylene group having 1 to 12 carbon atoms may be linear, branched, or cyclic, and specific examples 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.

The halogen atom may be a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or the like.

The alkyl group having 1 to 5 carbon atoms may be either linear or branched, and specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, and an n-pentyl group.

Specific examples of the alkylcarbonyl group having 1 to 5 carbon atoms include a methylcarbonyl (acetyl) group, an ethylcarbonyl group, an n-propylcarbonyl group, an n-butylcarbonyl group, and an n-pentylcarbonyl group.

Specific examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, and an n-pentyloxy group.

Specific examples of the divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms include a cyclopentanediyl group, a cyclohexanediyl group, a cycloheptanediyl group, and a cyclooctanediyl group.

Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

The alkyl group having 1 to 3 carbon atoms may be either linear or branched, and specific examples include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

The side chain a is more preferably one represented by the following formula (a1-1), (a1-2), (a2-1), (a3-1), (a4-1), (a5-1) or (a6-1).

(In the formula, L, ^A1 , ^A2 , ^Y1 , ^Y2 , ^P1 , ^Q1 , ^T1 , R, ^X1 , ^Z1a , ^Z2a , Cou, E, ^G1 , ^G2 , n1 and the dashed line are the same as above. ^P2 is a phenylene group or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms.)

The side chain represented by formula (a1-1) is preferably a side chain represented by the following formula (a1-1-1), and the side chain represented by formula (a1-2) is preferably 0 or a side chain represented by formula (a1-2-1).

(In the formula, n1, L, Q ¹ , X ¹ , R and the dashed line are the same as above.)

The side chain represented by formula (a2-1) is preferably a side chain represented by the following formula (a2-1-1).

(In the formula, L, ^A2 , ^Q1 , ^T1 , R and the dashed line are the same as above.)

The side chain represented by formula (a3-1) is preferably a side chain represented by the following formula (a3-1-1), (a3-1-2) or (a3-1-3).

(In the formula, L, Cou and the dashed line are the same as above.)

The side chain represented by formula (a4-1) is preferably a side chain represented by the following formula (a4-1-1), (a4-1-2), (a4-1-3) or (a4-1-4).

(In the formula, L, R and the dashed line are the same as above.)

The side chain represented by formula (a5-1) is preferably a side chain represented by the following formula (a5-1-1) or (a5-1-2).

(In the formula, L, R and the dashed line are the same as above.)

The side chain represented by formula (a6-1) is preferably a side chain represented by the following formula (a6-1-1), (a6-1-2) or (a6-1-3).

(In the formula, L, R and the dashed line are the same as above.)

(A) Side-chain block copolymer has a photosensitive side chain bonded to the main chain of the side-chain polymer block, and can undergo crosslinking, isomerization, or Fries rearrangement in response to optimal light selected from a wavelength range of 200 to 400 nm, particularly light with a wavelength of 254 nm, 313 nm, or 365 nm. The structure of the photosensitive side-chain polymer block 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 side-chain block copolymer is formed into a single-layer retardation film, stable optical anisotropy can be obtained.

A more specific example of the structure of the side chain type polymer block 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.

The side chain type polymer block may further include a side chain that does not undergo photodimerization or photoisomerization (hereinafter, also referred to as side chain b). Such side chain b is preferably one represented by any one of the following formulae (b1) to (b13), but is not limited thereto.

In formulae (b1) to (b13), ^A3 and ^A4 each independently represent a single bond, -O-, _-CH2- , -C(=O)-O-, -O-C(=O)-, -C(=O)-NH-, or -NH-C(=O)-. When the number of ^A4 is 2 or more, each ^A4 may be the same or different.
R ¹ 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 alkoxy group having 1 to 12 carbon atoms.
^R2 is a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, or a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with _-NO2 , -CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
^R3 is a hydrogen atom, _-NO2 , -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-, -OC(=O)-, -C(=O)-S- or -SC(=O)-.
a 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 represent a single bond, --C(═O)--, --CH ₂ --O--, or --CF ₂ --.
W ¹ , W ² and W ³ are each independently a single bond, -O-, -C(=O)-O-, -O-C(=O)-, -C(=O)-N(R')- or -N(R')-C(=O)-. When the number of W ² is 2 or more, each W ² may be the same or different. R' represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Q is an alkylene group having 1 to 10 carbon atoms, some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
L represents a single bond, an alkylene group having 1 to 12 carbon atoms, or a divalent linking group in which one or more of the -CH ₂ - constituting the alkylene group having 1 to 12 carbon atoms are replaced with -O-, -S-, -C(═O)-O-, or -O-C(═O)-, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
Q ¹ is a single bond, a phenylene group, a naphthylene group or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group and naphthylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. When the number of Q ¹ is 2 or more, each Q ¹ may be the same or different.
n1 is 0, 1, 2 or 3.
The hydrogen atoms on the benzene ring and the naphthalene ring 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 halogen atom, a cyano group, and a nitro group.
The dashed lines represent bonds.

Specific examples of the monovalent nitrogen-containing heterocyclic group include a pyrrolidinyl group, a piperidinyl group, a piperazinyl group, a pyrrolyl group, and a pyridyl group. Specific examples of the monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms include a cyclopentyl group and a cyclohexyl group. Examples of the alkyl group and alkoxy group include the same groups as those exemplified in the explanation of formulas (a1) to (a6).

The side chain type polymer block can be obtained by polymerizing a monomer that provides side chain a and, if necessary, a monomer that provides side chain b.

Examples of the monomer that provides the side chain a (hereinafter also referred to as the monomer MA) include compounds represented by the following formula (M1), (M2), (M3), (M4), (M5) or (M6).

(In the formula, PG is a polymerizable group, and ^A1 , ^A2 , ^D1 , L, ^T1 , ^Y1 , ^Y2 , ^P1 , ^Q1 , ^Q2 , R, Cou, E, ^X1 , ^X2 , ^Z1a , ^Z2a , ^G1 , ^G2 , n1 and n2 are the same as defined above.)

In formulae (M1) to (M6), PG is a polymerizable group, and is preferably a group represented by any one of the following formulae (PG1) to (PG7). Among them, from the viewpoint of ease of control of the polymerization reaction and stability of the polymer, an acrylic group or methacrylic group represented by formula (PG1) is preferred.

(In the formula, ^R is a hydrogen atom or a methyl group, and the dashed line is a bond to L.)

The compound represented by formula (M1) is preferably one represented by the following formula (M1-1-1) or (M1-2-1).

(In the formula, PG, L, ^Q1 , ^X1 , ^Y1 , ^Z1a , ^Z2a , ^P2 and R are the same as defined above.)

The compound represented by formula (M2) is preferably one represented by the following formula (M2-1).

(In the formula, PG, ^A2 , L, ^T1 , ^Y1 , ^Z1a , ^Z2a , ^P1 , ^Q1 and R are the same as defined above.)

The compound represented by formula (M3) is preferably one represented by the following formula (M3-1).

(In the formula, PG, A ¹ , L, X ¹ , Q ¹ , Cou and n1 are the same as defined above.)

The compound represented by formula (M4) is preferably one represented by the following formula (M4-1).

(In the formula, PG, ^A1 , L, ^X1 , ^Y1 , ^Y2 , ^Q1 , E, R and n1 are the same as defined above.)

The compound represented by formula (M5) is preferably one represented by the following formula (M5-1).

(In the formula, PG, ^A1 , L, ^X1 , ^Y1 , ^Y2 , ^Q1 , R and n1 are the same as defined above.)

The compound represented by formula (M6) is preferably one represented by the following formula (M6-1).

(In the formula, PG, ^A1 , L, ^X1 , ^Y1 , ^Y2 , ^Q1 , ^G1 , ^G2 , R and n1 are the same as defined above.)

The compound represented by formula (M1-1-1) is preferably one represented by the following formula (M1-1-2), and the compound represented by formula (M1-2-1) is preferably one represented by the following formula (M1-2-2).

(In the formula, PG, n1, L, ^Q1 , ^X1 and R are the same as defined above.)

The compound represented by formula (M2-1) is preferably one represented by the following formula (M2-2).

(In the formula, PG, ^A2 , L, ^T1 , ^Q1 and R are the same as above.)

The compound represented by formula (M3-1) is preferably one represented by the following formula (M3-2), (M3-3) or (M3-4).

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

The compound represented by formula (M4-1) is preferably one represented by the following formula (M4-2), (M4-3), (M4-4) or (M4-5).

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

The compound represented by formula (M5-1) is preferably one represented by the following formula (M5-2) or (M5-3).

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

The compound represented by formula (M6-1) is preferably one represented by the following formula (M6-2), (M6-3), or (M6-4).

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

Examples of compounds represented by formula (M1) include those represented by any of the following formulas (A-1-1-1) to (A-1-1-12). In the following formulas (A-1-1-1) to (A-1-1-12), PG is a polymerizable group, s1 represents the number of methylene groups and is an integer of 2 to 9, R ¹¹ is -H, -CH ₃ , -OCH ₃ , -C(CH ₃ ) ₃ , -C(═O)-CH ₃ or -CN, and R ¹² is -H, -CH ₃ , -CN or -F.

Further, examples of the compound represented by formula (M1) include those represented by any of the following formulae (A-1-2-1) to (A-1-2-4): In the following formulae, PG is a polymerizable group, and s1 is the same as defined above.

Specific examples of compounds represented by formula (M1) include 4-(6-methacryloxyhexyl-1-oxy)cinnamic acid, 4-(6-acryloxyhexyl-1-oxy)cinnamic acid, 4-(3-methacryloxypropyl-1-oxy)cinnamic acid, and 4-[4-(6-methacryloxyhexyl-1-oxy)benzoyloxy]cinnamic acid.

Examples of compounds represented by formula (M2) include those represented by any of the following formulas (A-2-1) to (A-2-9). In the following formulas (A-2-1) to (A-2-9), PG is a polymerizable group, and s1 and s2 represent the number of methylene groups and are each independently an integer of 2 to 9. R ²¹ is -CH ₃ , -OCH ₃ , -C(CH ₃ ) ₃ , -C(═O)-CH ₃ , -CN or -F.

Examples of the compound represented by formula (M3) include those represented by any of the following formulae (A-3-1) to (A-3-5): In the following formula, PG is a polymerizable group, and s1 is the same as defined above.

Examples of the compound represented by formula (M4) include those represented by any of the following formulae (A-4-1) to (A-4-4): In the following formula, PG is a polymerizable group, and s1 is the same as defined above.

Examples of the compound represented by formula (M5) include those represented by any of the following formulae (A-5-1) to (A-5-3): In the following formula, PG is a polymerizable group, and s1 is the same as defined above.

Examples of the compound represented by formula (M6) include those represented by any of the following formulae (A-6-1) to (A-6-3): In the following formula, PG is a polymerizable group, and s1 is the same as defined above.

Some of the above monomers are commercially available, and others can be produced by methods described, for example, in International Publication No. WO 2015/002292.

An example of a monomer that provides a side chain b that does not undergo photodimerization or photoisomerization (hereinafter also referred to as monomer MB) is a monomer that can form a mesogenic group in the side chain.

The mesogenic group 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 mesogenic group in the side chain preferably has the following structure.

Specific examples of monomer MB include a structure 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 having at least one of the structures represented by formulas (b1) to (b13). In particular, it is preferable that the monomer MB has a polymerizable group derived from a (meth)acrylate.

Preferred examples of the monomer MB include those represented by the following formulae (MB-1) to (MB-18), in which PG is a polymerizable group, and p is the number of methylene groups and is an integer of 2 to 9.

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

Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.

Specific examples of the acrylic acid ester compound 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-tricyclo[5.2.1.0(2,6)]decyl acrylate, 8-ethyl-8-tricyclo[5.2.1.0(2,6)]decyl acrylate, and the like.

Specific examples of the methacrylic acid ester compound 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-tricyclo[5.2.1.0(2,6)]decyl methacrylate, and 8-ethyl-8-tricyclo[5.2.1.0(2,6)]decyl methacrylate.

Specific examples of the vinyl compounds include vinyl ether, methyl vinyl ether, benzyl vinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, and propyl vinyl ether.

Specific examples of the styrene compound include styrene, 4-methylstyrene, 4-chlorostyrene, and 4-bromostyrene.

Specific examples of the maleimide compound include maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

In the side chain type polymer block, the content of side chain a and side chain b is not particularly limited. It may be a homopolymer with 100 mol% side chain a, or two or more types of side chain a may be used. In the case of a copolymer of side chain a and side chain b, the content of side chain a is preferably 5 to 99.9 mol%, more preferably 5 to 95 mol%, from the viewpoint of photoreactivity, and even more preferably 5 to 50 mol% from the viewpoint of photostability. Moreover, the content of side chain b is preferably 95 mol% or less, more preferably 5 to 95 mol%, from the viewpoint of photoreactivity, and even more preferably 50 mol% or more from the viewpoint of photostability. Even in the case of a copolymer, two or more types of side chain a and side chain b may be used.

The side chain type polymer block may contain other side chains. When the total content of side chain a and side chain b is less than 100 mol %, the content of the other side chains is the remaining portion.

The polymer block (A2) consisting of repeating units that do not contain photo-alignable side chains and liquid crystal side chains is a block that imparts flexibility to the polymer, which is the component (A). As the polymer block (A2) consisting of repeating units that do not contain photo-alignable side chains and liquid crystal side chains, a flexible block is preferable, and examples thereof include polyether and polysiloxane. The polymer block (A2) consisting of repeating units that do not contain photo-alignable side chains and liquid crystal side chains is easily introduced by a polymer type polymerization initiator. In the present invention, the polymer type polymerization initiator means a polymerization initiator having a polymer segment and a polymerization initiation active group. The polymer segment is the portion that becomes the polymer block consisting of repeating units that do not contain photo-alignable side chains and liquid crystal side chains in the side chain type block copolymer.

The polymer type polymerization initiator is preferably one having a repeating unit represented by the following formula (1).

In formula (1), R ^a1 to R ^a4 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, or a cyano group. R ^L1 and R ^L2 are each independently an alkylene group having 1 to 10 carbon atoms. L ¹ and L ² are each independently -C(=O)-O-, -O-C(=O)-, -C(=O)-NH-, or -NH-C(=O)-. X is a divalent group represented by the following formula (2) or (3).

In formulas (2) and (3), R ^a5 to R ^a8 are linear or branched alkyl groups having 1 to 6 carbon atoms or aryl groups having 6 to 12 carbon atoms. R ^L3 , R ^L4 , R ^L5 and R ^L6 are each independently an alkylene group having 1 to 10 carbon atoms. x and y are each independently a positive integer, usually 5 to 2,000, preferably 5 to 1,000, more preferably 10 to 300, and even more preferably 10 to 200.

Examples of linear or branched alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, cyclopentyl, and cyclohexyl groups.

The alkylene group having 1 to 10 carbon atoms may be linear, branched, or cyclic, and specific examples include methylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, 2-methylpropylene, 1-methylethylidene, and cyclohexylene.

Aryl groups having 6 to 12 carbon atoms include phenyl groups, 1-naphthyl groups, 2-naphthyl groups, 1-biphenylyl groups, and 2-biphenylyl groups.

R ^a1 to R ^a4 are preferably an alkyl group having 1 to 3 carbon atoms or a cyano group, and more preferably a methyl group or a cyano group.
R ^L1 and R ^L2 are preferably an alkylene group having 1 to 5 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms.
L ¹ is preferably -C(=O)-O- or -C(=O)-NH-. L ² is preferably -O-C(=O)- or -NH-C(=O)-. In particular, a combination of L ¹ being -C(=O)-O- and L ² being -O-C(=O)-, and a combination of L ¹ being -C(=O)-NH- and L ² being -NH-C(=O)- are more preferred.
With regard to X, R ^a5 to R ^a8 are preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group.
R ^L3 , R ^L4 , R ^L5 and R ^L6 are preferably an alkylene group having 1 to 5 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms.

Specific examples of the polymer type polymerization initiator include a polymeric azo polymerization initiator containing a polyethylene glycol unit represented by the following formula (In-1), and a polymeric azo polymerization initiator containing a polydimethylsiloxane unit represented by the following formula (In-2).

In formula (In-1) and formula (In-2), x and y are the same as above. n is a positive integer, usually 1 to 100, preferably 3 to 50, and more preferably 5 to 30.

As the polymer type polymerization initiator, commercially available products can be used, for example, VPE-0201 as the polymerization initiator represented by the formula (In-1) and VPS-1001N as the polymerization initiator represented by the formula (In-2) (both manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

The polymer block (A2) consisting of repeating units not containing photoalignable side chains and liquid crystalline side chains may be introduced by a polymer chain transfer agent. In the present invention, the polymer chain transfer agent means a chain transfer agent having a polymer segment and a site that receives radicals from a growing polymer chain to generate new radicals. The polymer segment is the portion that becomes the polymer block consisting of repeating units not containing photoalignable side chains and liquid crystalline side chains in the side chain type block copolymer.

The polymeric chain transfer agent is preferably one represented by the following formula (4).

In formula (4), Y is a linear or branched alkyl group having 1 to 3 carbon atoms, a hydroxyl group, a carboxyl group, or a sulfanyl group. R ^L7 and R ^L8 each independently represent a single bond or a linear or branched alkylene group having 1 to 6 carbon atoms. x is a positive integer.

The polymer block (A2) consisting of repeating units not including photoalignable side chains and liquid crystal side chains may be introduced by a monomer not including photoalignable side chains and liquid crystal side chains. After synthesizing the side chain type polymer block (A1), a monomer not including photoalignable side chains and liquid crystal side chains is added and polymerized to obtain a side chain type block copolymer consisting of each block. The polymerization method is not particularly limited, but examples thereof include living radical polymerization such as living radical polymerization (NMP) using a nitroxide as a dormant species, reversible addition-fragmentation chain transfer (RAFT) polymerization using a sulfur compound as a dormant, and reversible transfer catalyst polymerization (RTCP) using an alkyl iodide compound as a dormant species and a phosphorus compound, alcohol, or the like as a catalyst.

The method for producing the side chain type block copolymer is not particularly limited, and a general-purpose method that is used industrially can be used. Specifically, the side chain type block copolymer can be produced, for example, by a method including the following steps (1) and (2), but is not limited thereto.
Step (1): A step of mixing monomer MA, and if necessary monomer MB and other monomers, and a non-polymeric polymerization initiator, and carrying out radical polymerization in a solvent to form a side-chain type polymer block (A1). Step (2): A step of adding a polymeric polymerization initiator to the reaction liquid obtained in step (1), and carrying out radical polymerization in a solvent to incorporate a polymer block (A2) composed of repeating units not containing a photoalignable side chain and a liquid crystalline side chain.

　As the non-polymeric polymerization initiator for the radical polymerization in step (1), known compounds such as the radical thermal polymerization initiators and radical photopolymerization initiators shown below, 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 (2,2'-azobisisobutyronitrile, 2,2'-bis(2-hydroxyethyl)azobisisobutyronitrile, etc.). Such radical thermal polymerization initiators can be used alone or in combination of two or more.

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, isopropyl benzoin ether, and isopropyl benzoin ether. Butyl 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'-bis(tert-butylperoxycarbonyl)benzo Phenone, 3,4,4'-tris(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-(4'-methoxystyryl)-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'-methoxystyryl)-4,6-bis(trichloromethyl)-s-triazine styryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-pentyloxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 4-[p-N,N-bis(ethoxycarbonylmethyl)]-2,6-bis(trichloromethyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(2'-chlorophenyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(4'-methoxyphenyl)-s-triazine, 2-(p-dimethylamino styryl)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-hydroxyphenyl Cyclohexyl phenyl ketone, bis(5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, 3,3',4,4'-tetrakis(tert-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetrakis(tert-hexylperoxycarbonyl)benzophenone, 3,3'-bis(methoxycarbonyl)-4,4'-bis(t-butylperoxycarbonyl)benzophenone , 3,4'-bis(methoxycarbonyl)-4,3'-bis(tert-butylperoxycarbonyl)benzophenone, 4,4'-bis(methoxycarbonyl)-3,3'-bis(tert-butylperoxycarbonyl)benzophenone, 2-(3-methyl-3H-benzothiazol-2-ylidene)-1-naphthalen-2-yl-ethanone, or 2-(3-methyl-1,3-benzothiazol-2(3H)-ylidene)-1-(2-benzoyl)ethanone. These compounds 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, hexamethylphosphoric triamide, γ-butyrolactone, γ-valerolactone, isopropyl alcohol, methoxymethylpentanol, 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 carbitol, 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 Licorice 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, cyclopentanone, ethylene carbonate Examples of the organic solvent include propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, 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. These 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 solvent described above to the extent that the polymer produced does not precipitate.

In addition, since oxygen in an organic solvent during radical polymerization can inhibit the polymerization reaction, it is preferable to use an organic solvent that has been degassed to the extent possible.

The polymerization temperature during radical polymerization can be selected from any temperature in the range of 20 to 150°C, but is preferably in the range of 30 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 liquid 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 in the early stages, and then an organic solvent can be added.

In the radical polymerization reaction in step (1) above, 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 15 mol %. In addition, various monomer components, solvents, initiators, etc. can also be added during polymerization.

In the radical polymerization reaction in step (2), the amount of polymeric polymerization initiator used is preferably 0.01 to 0.2 per 1 of the total amount of monomers that give the side chain type polymer block, in terms of molar ratio, taking into account the half-life of the polymeric polymerization initiator and in order to smoothly advance the radical polymerization. In addition, various monomer components, solvents, initiators, etc. can also be added during polymerization.

The side-chain block copolymer produced from the reaction solution obtained by the above reaction can be recovered by precipitating the reaction solution by pouring the reaction solution into a poor solvent, but this reprecipitation process is not essential. 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 a 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 impurities in the polymer. Examples of poor solvents in this case include alcohols, ketones, and hydrocarbons, and it is preferable to use three or more poor solvents selected from these because this further increases the efficiency of purification.

The ratio (molar ratio) of the side chain polymer block to the initiator-derived polymer block in the side chain block copolymer is roughly based on the total amount of monomers that give the side chain polymer block and the amount of polymeric polymerization initiator used.

The weight average molecular weight (Mw) of the photosensitive side chain type polymer block (A1) capable of expressing liquid crystallinity is preferably 5,000 to 300,000. The number average molecular weight (Mn) of the polymer block (A2) consisting of repeating units that do not contain photoalignable side chains and liquid crystal side chains is preferably 200 to 10,000.

The weight average molecular weight (Mw) of the side chain type block copolymer used in the present invention is preferably 5,200 to 310,000, more preferably 5,500 to 250,000, and even more preferably 6,000 to 200,000, taking into consideration the strength of the resulting coating film, the workability during coating film formation, and the uniformity of the coating film. Note that in the present invention, Mn and Mw are values measured in terms of polystyrene using the gel permeation chromatography (GPC) method.

[(B) Organic Solvent]
The polymer composition of the present invention contains an organic solvent (good solvent). The organic solvent (good solvent) 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, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethylphosphoramide, 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, cyclopentanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, tetrahydrofuran, and tetrahydrofurfuryl alcohol. These may be used alone or in combination of two or more.

The polymer composition may also contain components other than the side chain type block copolymer and the organic solvent (good solvent). Examples of such components include, but are not limited to, solvents (poor solvents) or compounds that improve the film thickness uniformity and surface smoothness when the polymer composition is applied, and compounds that improve the adhesion between the retardation film and the substrate.

Specific examples of solvents (poor solvents) that improve the film thickness uniformity and surface smoothness include isopropyl alcohol, methoxymethyl pentanol, methyl cellosolve, ethyl 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 (butyl cellosolve), 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-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 , ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-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 monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, and other solvents with low surface tension.

The poor solvent may be used alone or in combination of two or more. When a poor solvent is used, its content in the solvent is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, so as not to significantly reduce the solubility of the polymer.

The 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) F-171, F-173, F-563, R-30, and R-40 (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 Chemicals). 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 the side chain type block copolymer.

Specific examples of compounds that improve the adhesion between the retardation film 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-triethoxysilylpropyltriethoxysilane, Examples include ethylenetriamine, 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.

The polymer composition may contain a phenoplast-based compound or an epoxy group-containing compound to improve adhesion between the substrate and the retardation film, as well as to prevent deterioration of characteristics due to backlight when a polarizing plate is formed.

Specific examples of the phenoplast-based compound include, but are not limited to, those shown below.

Specific examples of the epoxy group-containing compound 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, its 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 side-chain block copolymer contained in the polymer composition. If the content is less than 0.1 parts 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-naphthothiazolidine, etc.), and benzoylmethylene-3-methyl-β-naphthothiazolidine. benzothiazoline, 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 may contain dielectric or conductive substances to change the electrical properties of the retardation film, such as the dielectric constant or conductivity, and may also contain crosslinking compounds to increase the hardness and density of the film when made into a retardation film, as long as the effects of the present invention are not impaired.

The polymer composition is preferably prepared as a coating liquid suitable for forming a single-layer retardation film. That is, the polymer composition used in the present invention is preferably prepared as a solution in which the side-chain type block copolymer, the compound that improves the film thickness uniformity and surface smoothness described above, and the compound that improves adhesion to the substrate are dissolved in an organic solvent (good solvent).

The content of the side chain type block copolymer in the polymer composition is preferably 1 to 30% by mass, and more preferably 3 to 25% by mass.

The polymer composition may contain other polymers in addition to the side chain type block copolymer, as long as the liquid crystal expression ability and photosensitive performance are not impaired. Examples of the other polymers include polymers that do not contain photosensitive side chains that can express liquid crystallinity, such as poly(meth)acrylate, polyamic acid, and polyimide. When the other polymers are contained, the content thereof is preferably 0.5 to 80% by mass, and more preferably 1 to 50% by mass, of the total polymer components.

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 of the phase difference material, such as the dielectric constant or conductivity, and may also contain 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), the solvent or compound that improves the thickness uniformity and surface smoothness described above, and the compound that improves the adhesion between the liquid crystal alignment film and the substrate are dissolved in the organic solvent of the component (B). Here, the content of the component (A) is preferably 1 to 30% by mass, more preferably 3 to 25% by mass in the polymer composition of the present invention.

[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) a step of applying the polymer 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 polymer composition of the present invention onto a substrate to form a coating film. More specifically, the polymer composition of the present invention is applied onto a substrate (e.g., a silicon/silicon dioxide-coated substrate, a silicon nitride substrate, a glass 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 triacetyl cellulose (TAC) film, a cycloolefin polymer film, a polyethylene terephthalate film, an acrylic film, or other resin 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 hot air 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 achieves 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.

The heating can be performed using a heating means such as a hot plate, a hot air 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 polymer 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 by 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 become closer 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 a phase transition occurs on the polymer or coating surface from a solid phase to a liquid crystal phase, and is equal to or lower than the isotropic phase transition temperature (Tiso) at which a phase transition occurs from a liquid crystal phase to an isotropic phase. For example, manifesting liquid crystallinity at 130°C or lower means that the liquid crystal transition temperature at which a phase transition occurs from a solid phase to a liquid crystal phase is 130°C or lower.

The thickness of the coating film formed after heating can be appropriately selected taking into consideration the unevenness of the substrate used and the optical and electrical properties, and is preferably 0.5 to 10 μm, for example.

The single-layer retardation material of the present invention obtained in this manner has 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, preparation examples, working examples and comparative examples, but the present invention is not limited to the following examples.

The monomers having a photoreactive group, MA-1 and MA-8, and the monomers having a non-photosensitive group, MA-2 to MA-7, used in the examples are shown below. Note that the side chains derived from MA-1 and MA-8 exhibit both photoreactivity and liquid crystallinity, while the side chains derived from MA-2 to MA-7 exhibit only liquid crystallinity.

The abbreviations of the reagents used in this example are as follows:
(Organic solvent)
NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve PGME: 1-methoxy-2-propanol PGMEA: Propylene glycol monomethyl ether acetate CPN: Cyclopentanone (polymerization initiator)
AIBN: 2,2'-azobisisobutyronitrile VPE: polyethylene glycol unit-containing polymeric azo polymerization initiator represented by the formula (In-1) (VPE-0201 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight of polyethylene glycol unit: about 2,000)
(Surfactant)
F563: Megafac F-563 (manufactured by DIC)
R40: Megafac R-40 (manufactured by DIC)

(Measurement of molecular weight)
The molecular weight of the polymer was measured using a room temperature gel permeation chromatography (GPC) apparatus (CBM-20A) (manufactured by Shimadzu Corporation) and a column (Shodex (registered trademark) KF-804L and KF-803L in series) (manufactured by Showa Denko KK) as follows.
Column temperature: 40°C
Eluent: tetrahydrofuran Flow rate: 1.0 mL/min Standard sample for creating calibration curve: standard polystyrene (molecular weight: 197,000, 55,100, 12,800, 3,950, 1,260) (manufactured by Tosoh Corporation)

[1] Polymer synthesis <Synthesis Example 1>
M-1 (3.79 g, 11.4 mmol), M-2 (2.33 g, 7.60 mmol), M-3 (4.23 g, 15.2 mmol), M-4 (1.45 g, 3.80 mmol) and AIBN (0.62 g, 3.80 mmol) were dissolved in NMP (22.4 g) to prepare a monomer mixed solution. In addition, VPE (0.62 g) was dissolved in NMP (1.86 g) to prepare an additional addition solution. Under a nitrogen atmosphere, the monomer mixed solution was dropped into NMP (14.9 g) heated to 70 ° C. over 2 hours. After the end of the dropwise addition, the reaction was carried out at 70 ° C. for 3 hours to obtain a solution of a polymer (weight average molecular weight Mw: 45,700) corresponding to the side chain type polymer block (A1). Furthermore, under a nitrogen atmosphere, the additional addition solution was dropped into the above solution at 80 ° C. over 60 minutes. After the end of the dropwise addition, the reaction was carried out at 80 ° C. for 12 hours. After the reaction was completed, the reaction solution was added to methanol (300 g) and the resulting precipitate was filtered off. The filtered product was washed with methanol and dried under reduced pressure at 40° C. to obtain polymer powder P-1.

<Synthesis Examples 2 to 8>
As shown in Table 1 below, polymer powders P-2 to P-8 were obtained by carrying out the same operations as in Synthesis Example 1, except that the type and amount of the monomer used and the amount of the polymerization initiator VPE were changed.

<Synthesis Example 9>
M-1 (3.79 g, 11.4 mmol), M-2 (2.33 g, 7.60 mmol), M-3 (4.23 g, 15.2 mmol), M-4 (1.45 g, 3.80 mmol) and AIBN (0.62 g, 3.80 mmol) were dissolved in NMP (22.4 g) to prepare a monomer mixed solution. The monomer mixed solution was dropped into NMP (14.9 g) heated to 70 ° C. over 2 hours under a nitrogen atmosphere. After the dropwise addition, the reaction was allowed to proceed at 70 ° C. for 12 hours. After the reaction was completed, the reaction solution was added to a mixed solution of methanol (250 g) and pure water (50 g), and the resulting precipitate was filtered off. The filtered product was washed with methanol and dried under reduced pressure at 40 ° C. to obtain polymer powder P-9.

<Synthesis Example 10>
Polymer powder P-10 was obtained by carrying out the same procedure as in Synthesis Example 9, except that the types and amounts of the monomers used were changed as shown in Table 1 below.

<Synthesis Example 11>
M-1 (1.99 g, 6.00 mmol), M-2 (10.4 g, 34.0 mmol), and AIBN (0.66 g, 4.00 mmol) were dissolved in NMP (18.3 g) to prepare a monomer mixture solution. The monomer mixture solution was added dropwise to NMP (9.5 g) heated to 70° C. under a nitrogen atmosphere over a period of 2 hours. After completion of the addition, the mixture was reacted at 70° C. for 12 hours. After completion of the reaction, the solution was returned to room temperature to obtain polymer solution P-11.

<Synthesis Example 12>
M-1 (1.99 g, 6.00 mmol), M-2 (10.4 g, 34.0 mmol), and VPE (8.0 g) were dissolved in NMP (38.1 g) to prepare a monomer mixture solution. The monomer mixture solution was added dropwise to NMP (9.5 g) heated to 80° C. under a nitrogen atmosphere over 1.5 hours. After the dropwise addition was completed, the mixture was reacted at 80° C. for 20 hours. After the reaction was completed, the solution was returned to room temperature to obtain polymer solution P-12.

[2] Preparation of retardation film forming material <Preparation Example 1>
NMP (1.0 g), BCS (1.0 g), PGME (3.5 g), PGMEA (2.7 g) and F563 (9.0 mg) were added to the polymer powder P-1 (1.8 g) obtained in Synthesis Example 1 and stirred. This was filtered through a filter with a pore size of 5.0 μm to obtain a polymer preparation solution T-1. This polymer preparation solution T-1 was used as it is as a material for forming a retardation film.

<Preparation Examples 2 to 10>
As shown in Table 2 below, polymer preparation solutions T-2 to T-10 were obtained by carrying out the same operation as in Preparation Example 1, except that the type and amount of polymer powder and the amount of solvent and additives introduced were changed.

<Preparation Example 11>
To the polymer solution P-11 (6.7 g) obtained in Synthesis Example 11, BCS (2.0 g), CPN (1.3 g) and R40 (10.0 mg) were added and stirred. This was filtered through a filter with a pore size of 5.0 μm to obtain a polymer preparation solution T-11. This polymer preparation solution T-11 was used as it is as a material for forming a retardation film.

<Preparation Example 12>
As shown in Table 2 below, the same operation as in Preparation Example 11 was carried out except that the type of polymer solution was changed, to obtain Polymer Preparation Solution T-12.

[3] Production of single-layer retardation film <Example 1>
Polymer preparation solution T-1 was applied to a non-alkali glass substrate using a bar coater to a film thickness of about 3.8 μm. The substrate was dried in a hot air circulating oven at 80° C. for 3.5 minutes, and then irradiated with ultraviolet light (100 to 1,200 mJ/cm ² ) having a wavelength of 365 nm from a high-pressure mercury lamp through a cut filter (365 nm bandpass filter) and a polarizing plate. The substrate was heated in an IR oven at 160° C. for 20 minutes to prepare glass substrate S-1 with a retardation film.

<Examples 2 to 8, Comparative Examples 1 and 2>
As shown in Table 3 below, glass substrates with retardation films S-2 to S-8 and R-1 to R-2 were obtained by performing the same operation as in Example 1, except that the type of polymer preparation solution, the film thickness, and the baking conditions were changed.

<Comparative Example 3>
Polymer preparation solution T-11 was applied to a non-alkali glass substrate by spin coating to a film thickness of about 2.0 μm. The substrate was dried on a hot plate at 60° C. for 4 minutes, and then irradiated with ultraviolet light (50 to 800 mJ/cm ² ) having a wavelength of 365 nm from a high-pressure mercury lamp through a cut filter (365 nm bandpass filter) and a polarizing plate. The substrate was heated in an IR oven at 120° C. for 20 minutes to prepare glass substrate R-3 with a retardation film.

<Comparative Example 4>
As shown in Table 3 below, except that the type of the polymer preparation solution was changed, the same operation as in Comparative Example 3 was carried out to obtain a glass substrate R-4 with a retardation film.

The retardation, haze, NZ coefficient, and exposure margin of each of the retardation film-coated substrates S-1 to S-8 and R-1 to R-4 were evaluated using the following methods.

[Phase difference evaluation]
The linear phase difference at a wavelength of 550 nm was measured using AxoScan manufactured by Axometrics, and Δn was calculated using the following formula. The optimum exposure amount at which Δn was maximized and the value of Δn at that time are shown in Table 4.
Δn=phase difference value [nm]/film thickness [nm]
Retardation value: Linear retardation measured by Axo Scan Film thickness: Measured film thickness of retardation film

[Haze evaluation]
Using a HAZE METER HZ-V3 manufactured by Suga Test Instruments, the substrate was placed so that the light from the light source was perpendicular to the substrate, and the haze was measured at room temperature. The results are summarized in Table 4.

[NZ coefficient evaluation]
The refractive indexes of the retardation film in the three-dimensional direction at a wavelength of 550 nm were measured using an AxoScan manufactured by Axometrics, and the NZ coefficient was calculated. The NZ coefficient is an index of the magnitude relationship of the three-dimensional refractive index and is expressed by the following formula.
NZ coefficient = (nx - nz) / (nx - ny)
nx: refractive index in the x-axis direction (slow axis direction), ny: refractive index in the y-axis direction (direction perpendicular to the slow axis), and nz: refractive index in the z-axis direction (thickness direction). The results of calculations for the glass substrates S-1 to S-8 and R-1 to R-4 with retardation films, assuming that the average refractive index of the retardation film is 1.55, are summarized in Table 4.

[Exposure Margin Evaluation]
When the exposure dose was increased or decreased by 200 mJ/ ^cm2 from the optimal exposure dose at which Δn was maximized, a change in the NZ coefficient of 0.05 or less was evaluated as "◎", a change in the NZ coefficient of more than 0.05 and 0.15 or less was evaluated as "◯", and a change in the NZ coefficient of more than 0.15 was evaluated as "×". The results are summarized in Table 4.

From the results of Comparative Example 3 and Comparative Example 4 in Table 4, when all the polymerization initiators were replaced with polymeric polymerization initiators (from the low molecular weight polymerization initiator used in Comparative Example 3 to the polymeric polymerization initiator used in Comparative Example 4), the haze was suppressed, but Δn was significantly reduced. On the other hand, when a polymeric polymerization initiator was additionally added as in Examples 1 to 8, the haze was suppressed while maintaining a high value of Δn. In order to express a sufficient retardation, it is necessary for the side chain components to form a continuous block, and it is considered that Examples 1 to 8, in which the polymerization reaction proceeded even before the introduction of the polymeric polymerization initiator, maintained a high Δn. In addition, it is considered that the formation of polydomains was inhibited by incorporating a polymer block consisting of a repeating unit that does not contain a photoalignable side chain and a liquid crystal side chain into the side chain type polymer block, and the scattering of light transmitted through the film was reduced, thereby suppressing the haze.
Furthermore, in the Examples, the values of the NZ coefficient were shifted to the positive side compared to the Comparative Examples in which a polymer block consisting of a repeating unit not containing a photoalignable side chain and a liquid crystalline side chain was not introduced. Also, a wide exposure margin for the NZ coefficient was confirmed in the Examples. In Examples 1 to 8, it is considered that the alignment was stabilized and a wide exposure margin was obtained because the block copolymer consisting of a side chain type polymer block and a polymer block consisting of a repeating unit not containing a photoalignable side chain and a liquid crystalline side chain formed microphase separation.

Claims

A polymer composition comprising: (A) a block copolymer having a photosensitive side-chain type polymer block (A1) capable of exhibiting liquid crystallinity and a polymer block (A2) consisting of repeating units that do not contain photoalignable side chains or liquid crystal side chains; and (B) an organic solvent.
The polymer composition according to claim 1, wherein the side chain type polymer block (A1) has a side chain represented by any one of the following formulas (a1) to (a6):

(In the formula, n1 and n2 each independently represent 0, 1, 2, or 3.
L is a single bond or an alkylene group having 1 to 12 carbon atoms, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
T 1 is a single bond or an alkylene group having 1 to 12 carbon atoms, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
A 1 , A 2 and D 1 each independently represent a single bond, -O-, -CH 2 -, -C(═O)-O-, -O-C(═O)-, -C(═O)-NH- or -NH-C(═O)-, provided that when T 1 is a single bond, A 2 is also a single bond.
Y1 and Y2 are a phenylene group or a naphthylene group, and some or all of the hydrogen atoms of the phenylene group and the naphthylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
P 1 , Q 1 and Q 2 are each independently a single bond, a phenylene group or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, in which some or all of the hydrogen atoms of the phenylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. When the number of Q 1s is 2 or more, each Q 1 may be the same as or different from another, and when the number of Q 2s is 2 or more, each Q 2 may be the same as or different from another.
R is a hydrogen atom, a cyano group, a halogen atom, a carboxy group, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
X 1 and X 2 are each independently a single bond, -O-, -C(=O)-O-, -O-C(=O)-, -N=N-, -CH=CH-, -C≡C-, -CH=CH-C(=O)-O-, or -O-C(=O)-CH=CH-. When the number of X 1 is 2 or more, each X 1 may be the same as or different from each other, and when the number of X 2 is 2 or more, each X 2 may be the same as or different from each other.
Z 1a and Z 2a each independently represent a hydrogen atom, a halogen atom, a cyano group or an alkyl group having 1 to 3 carbon atoms, and some or all of the hydrogen atoms of this alkyl group may be substituted with fluorine atoms.
Cou is a coumarin-6-yl group or a coumarin-7-yl group, and some of the hydrogen atoms bonded to these may be substituted with -NO2 , -CN, -CH=C(CN) 2 , -CH=CH-CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
E is -C(=O)-O-, -OC(=O)-, -C(=O)-S- or -SC(=O)-.
G 1 and G 2 are each independently N or CH.
The dashed lines represent bonds.)
The polymer composition according to claim 1, wherein the side chain type polymer block (A1) further has a side chain that does not undergo photodimerization or photoisomerization.
The polymer composition according to claim 3, wherein the side chain which is neither photodimerized nor photoisomerized is represented by any one of the following formulas (b1) to (b13):

(In the formula, A3 and A4 each independently represent a single bond, -O-, -CH2- , -C(=O)-O-, -O-C(=O)-, -C(=O)-NH-, or -NH-C(=O)-. When the number of A4 's is 2 or more, each A4 may be the same or different.
R 1 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 alkoxy group having 1 to 12 carbon atoms.
R2 is a phenyl group, a naphthyl group, a biphenylyl group, a furanyl group, a monovalent nitrogen-containing heterocyclic group, or a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with -NO2 , -CN, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.
R3 is a hydrogen atom, -NO2 , -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-, -OC(=O)-, -C(=O)-S- or -SC(=O)-.
a 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 represent a single bond, --C(═O)--, --CH 2 --O--, or --CF 2 --.
W 1 , W 2 and W 3 are each independently a single bond, -O-, -C(=O)-O-, -O-C(=O)-, -C(=O)-N(R')- or -N(R')-C(=O)-. When the number of W 2 is 2 or more, each W 2 may be the same or different. R' represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
Q is an alkylene group having 1 to 10 carbon atoms, some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
L represents a single bond, an alkylene group having 1 to 12 carbon atoms, or a divalent linking group in which one or more of the -CH 2 - constituting the alkylene group having 1 to 12 carbon atoms are replaced with -O-, -S-, -C(═O)-O-, or -O-C(═O)-, and some or all of the hydrogen atoms of the alkylene group may be substituted with halogen atoms.
Q 1 is a single bond, a phenylene group, a naphthylene group or a divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, and some or all of the hydrogen atoms of the phenylene group and naphthylene group may be substituted with a cyano group, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkylcarbonyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. When the number of Q 1 is 2 or more, each Q 1 may be the same or different.
n1 is 0, 1, 2 or 3.
The hydrogen atoms on the benzene ring and the naphthalene ring 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 halogen atom, a cyano group, and a nitro group.
The dashed lines represent bonds.)
The polymer composition according to claim 1, wherein the polymer block (A2) consisting of repeating units not containing a photoalignable side chain and a liquid crystal side chain is a polymer block derived from a polymeric polymerization initiator.
The polymer composition according to claim 5 , wherein the polymer type polymerization initiator has a repeating unit represented by the following formula (1):

(In the formula, R a1 to R a4 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, or a cyano group. R L1 and R L2 are each independently an alkylene group having 1 to 10 carbon atoms. L 1 and L 2 are each independently -C(=O)-O-, -O-C(=O)-, -C(=O)-NH-, or -NH-C(=O)-. X is a divalent group represented by the following formula (2) or (3).)

(In the formula, R a5 to R a8 are a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. R L3 , R L4 , R L5 and R L6 are each independently an alkylene group having 1 to 10 carbon atoms. x and y are each independently a positive integer.)
The polymer composition according to claim 6, wherein the polymer type polymerization initiator is represented by any one of the following formulas (In-1) to (In-2):

(In the formula, x and y are the same as above, and n is a positive integer.)
The polymer composition according to claim 1, wherein the polymer block (A2) consisting of repeating units not containing a photoalignable side chain and a liquid crystalline side chain is a polymer block derived from a polymeric chain transfer agent.
The polymer composition according to claim 8, wherein the polymeric chain transfer agent is represented by the following formula (4):

(In the formula, Y is a linear or branched alkyl group having 1 to 3 carbon atoms, a hydroxyl group, a carboxyl group, or a sulfanyl group. R and R are each independently a single bond or a linear or branched alkylene group having 1 to 6 carbon atoms. x is a positive integer.)
The polymer composition according to claim 1, wherein the photosensitive side-chain polymer block (A1) capable of exhibiting liquid crystallinity has a number average molecular weight of 5,000 to 300,000.
The polymer composition according to claim 1, wherein the number average molecular weight of the polymer block (A2) consisting of repeating units that do not contain photoalignable side chains and liquid crystalline side chains is 200 to 10,000.
(I) a step of applying the polymer composition according to any one of claims 1 to 11 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.
A single-layer retardation material obtained from the polymer composition according to any one of claims 1 to 11.