JP2023019407A - Resin composition for liquid crystal alignment film - Google Patents

Abstract

To provide a resin composition for liquid crystal alignment film having alignment capability to driving liquid crystal and polymerizable liquid crystal, heat resistance, transparency, and adhesion property to a base; to provide a thin film including the resin composition for liquid crystal alignment film of the present invention and; to provide an electronic component such as a liquid crystal display element or a solid-state imaging element having the thin film.SOLUTION: Disclosed is a resin composition for a liquid crystal alignment film which includes: a polymer (A); and a solvent (B), and the repeating unit in the polymer (A) has a structure represented by a formula (1). In the formula (1), each of R1, R2, R3, R4 and R5 independently represents H, CH3, OCH3 or, OH, and at least one of R1, R2, R3, R4 and R5 represents OH.SELECTED DRAWING: None

Description

The present invention provides a resin composition for a liquid crystal alignment film, a thin film comprising the composition and having alignment ability, heat resistance, transparency and adhesion to a substrate, and a liquid crystal display device, solid-state imaging device, etc. having the thin film. of electronic components.

A liquid crystal display device is provided with a retardation film in order to widen the viewing angle, adjust the image color tone, and the like. As such a retardation film, a stretched polymer film or a coating type thin film made of a polymerizable liquid crystal composition is used. A coating-type thin film made of a polymerizable liquid crystal composition makes it possible to reduce the thickness of a liquid crystal display device and improve the display quality by reducing the thickness of a retardation film and improving the durability as compared with a conventional polymer film.

A retardation film using a polymerizable liquid crystal is obtained by coating a polymerizable liquid crystal composition solution on a substrate having an alignment film subjected to alignment treatment, aligning the polymerizable liquid crystal composition, and then applying the polymerizable liquid crystal composition. (Patent Document 1). A rubbing method, a photo-alignment method, and the like are known as alignment treatment methods. As the alignment film for the polymerizable liquid crystal, it is possible to use the alignment film for the drive liquid crystal. The liquid crystal alignment film in this specification includes both the alignment film for driving liquid crystal and the alignment film for polymerizable liquid crystal.

A color filter is used as one method for colorizing a liquid crystal display element. In order to expand the display color gamut, finely divided pigments and dyes are used in color filters. -methyl-2-pyrrolidone (hereinafter referred to as "NMP"). A color filter that has been corroded by a solvent undergoes deterioration such as color change and color loss, resulting in deterioration in the display quality of a liquid crystal display element. In order to suppress this, a method of forming a protective film on the color filter and forming a liquid crystal alignment film thereon is adopted.

With the spread of liquid crystal display devices, there is a demand for reduction in manufacturing costs such as shortening of the manufacturing process, and development of materials that provide multiple functions to one coating film layer is required. When the two layers of the protective film and the liquid crystal alignment film formed on the color filter are made into a single layer film, the single layer film has heat resistance, adhesion to the substrate, and high transmittance in addition to the alignment ability. Also, the composition is required not to use a solvent that corrodes the color filter.

Polyimide, polyamic acid, polymethyl methacrylate, and the like are known as polymers having alignment ability. Among these, depending on the structure of the polymer, liquid crystal molecules can be aligned vertically to the substrate surface (homeotropic alignment), and those can be aligned horizontally to the substrate surface (homogeneous alignment). , which are selected according to the device design. A polyamic acid having a side chain structure is well known as a polymer that can be vertically aligned. However, the composition must contain NMP as a solvent due to the problem of polymer deposition, and is not suitable for use as a protective film. There are few reported examples of a resin composition for a liquid crystal alignment film that exhibits vertical alignment ability without containing NMP in the solvent, and examples using polyacrylate have been reported, but there is room for improvement in terms of heat resistance and adhesion to the substrate. There is (Patent Document 2).

JP 2007-148098 A JP 2018-194709 A

An object of the present invention is to provide a resin composition for a liquid crystal alignment film which has alignment ability for driving liquid crystals and polymerizable liquid crystals, heat resistance, transparency, and adhesion to a substrate. Provide a thin film made of the resin composition for a liquid crystal alignment film of the present invention. To provide an electronic component such as a liquid crystal display device and a solid-state imaging device having the thin film.

As a result of intensive studies to solve the above problems, the present inventors have found that by using a resin composition for a liquid crystal alignment film containing a hydroxyvinyl polymer made from a raw material containing a hydroxyvinyl monomer, alignment capability, heat resistance and substrate The inventors have found that a highly transparent thin film having good adhesion to the film can be obtained, and completed the present invention.

式（１）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４およびＲ^５はそれぞれ独立にＨ、ＣＨ_３、ＯＣＨ_３、またはＯＨであり、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４およびＲ^５のうちの少なくとも１つはＯＨである。
［２］ 式（１）において、Ｒ^３がＯＨである、［１］に記載の液晶配向膜用樹脂組成物。
［３］ 式（１）において、Ｒ^１、Ｒ^２、Ｒ^４およびＲ^５がＨである、［２］に記載の液晶配向膜用樹脂組成物。
［４］ さらに、架橋剤、重合性二重結合を有する化合物、界面活性剤、密着性向上剤および酸化防止剤からなる群から選択された少なくとも１種の添加剤を含む、［１］～［３］のいずれか１項に記載の液晶配向膜用樹脂組成物。
［５］ 架橋剤を含み、さらに重合性二重結合を有する化合物、界面活性剤、密着性向上剤および酸化防止剤からなる群から選択された少なくとも１種の添加剤を含む、［４］に記載の液晶配向膜用樹脂組成物。
［６］ ［１］～［５］のいずれか１項に記載の液晶配向膜用樹脂組成物から得られる薄膜。
［７］ ［６］に記載の薄膜を有する液晶表示素子。 The present invention includes the following configurations.
[1] A resin composition for a liquid crystal alignment film containing a polymer (A) and a solvent (B), wherein the repeating unit in the polymer (A) has a structure represented by formula (1). Resin composition.

In formula (1), R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently H, CH ₃ , OCH ₃ or OH, R ¹ , R ² , R ³ , R ⁴ and R At least one of ⁵ is OH.
[2] The resin composition for a liquid crystal alignment film according to [1], wherein in formula (1), ^R3 is OH.
[3] The resin composition for a liquid crystal alignment film according to [2], wherein in formula (1), R ¹ , R ² , R ⁴ and R ⁵ are H.
[4] Further, [1]-[ 3] The resin composition for a liquid crystal alignment film according to any one of the above items.
[5] containing a cross-linking agent and further containing at least one additive selected from the group consisting of a compound having a polymerizable double bond, a surfactant, an adhesion improver and an antioxidant, to [4] The resin composition for a liquid crystal alignment film as described above.
[6] A thin film obtained from the resin composition for a liquid crystal alignment film according to any one of [1] to [5].
[7] A liquid crystal display device comprising the thin film according to [6].

The resin composition for a liquid crystal alignment film of the present invention has a specific structure, and the resulting thin film has the ability to vertically align liquid crystal molecules, has heat resistance and transparency, and has excellent adhesion to the substrate. Therefore, it can be used both as a liquid crystal alignment film and as a protective film.
Moreover, since the resin composition for a liquid crystal alignment film of the present invention can be produced without NMP in the solvent, it is possible to suppress erosion of the substrate during film formation.

4 is a graph showing the relationship between the incident angle and the phase difference in alignment ability evaluation in Example 1. FIG.

式（１）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４およびＲ^５はそれぞれ独立にＨ、ＣＨ_３、ＯＣＨ_３、またはＯＨであり、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４およびＲ^５のうちの少なくとも１つはＯＨである。 1. Polymer (A)
The polymer (A) of the present invention is a polymer whose repeating unit has a structure represented by formula (1).

In formula (1), R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently H, CH ₃ , OCH ₃ or OH, R ¹ , R ² , R ³ , R ⁴ and R At least one of ⁵ is OH.

From the viewpoint of providing good alignment ability, the form in which R ³ is OH in the structure represented by formula (1) is preferable, R ³ is OH, and R ¹ , R ² , R ⁴ and R ⁵ are H is more preferred.

式（２）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４およびＲ^５はそれぞれ独立にＨ、ＣＨ_３、ＯＣＨ_３、またはＯＨであり、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４およびＲ^５のうちの少なくとも１つはＯＨである。 1-1. Monomer Used for Synthesis of Polymer (A) The polymer (A) of the present invention can be obtained by polymerizing the compound represented by formula (2).

In formula (2), R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently H, CH ₃ , OCH ₃ or OH, R ¹ , R ² , R ³ , R ⁴ and R At least one of ⁵ is OH.

Preferred examples of the compound represented by formula (2) include 2-vinylphenol, 3-vinylphenol and 4-vinylphenol. Any one of these compounds may be used, or two or more may be used.

The polymer (A) is preferably a copolymer containing 4-vinylphenol, more preferably a homopolymer of 4-vinylphenol, from the viewpoint of providing good alignment ability.

1-2. Solvent Used for Polymerization Reaction of Polymer (A) A solvent is preferably used for synthesis of the polymer (A). The solvent used in the polymerization reaction to obtain the polymer (A) (hereinafter sometimes referred to as "polymerization solvent") is a solvent capable of dissolving the monomers used in synthesizing the polymer (A) and the resulting polymer (A). Preferably. Specific examples of polymerization solvents include methanol, ethanol, 1-propanol, 2-propanol, propylene glycol, acetone, methyl isobutyl ketone, 2-butanone, ethyl acetate, propyl acetate, butyl acetate, tetrahydrofuran, acetonitrile, dioxane, toluene, and xylene. , cyclohexanone, cyclopentanone, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate , N,N-dimethylformamide, and acetic acid. The polymerization solvent can be one of these or a mixture of two or more of these.

The polymer (A) obtained as a polymer solution may be used for the preparation of the resin composition for a liquid crystal alignment film while leaving the solvent as it is, or the solvent may be removed in consideration of transportability. You may use for preparation of the resin composition for liquid crystal aligning films as a polymer solid. When the polymer solution is used for the preparation of the resin composition for liquid crystal alignment film as it is, the polymerization solvent contained in the polymer solution is also included in the solvent (B).

1-3. Method for Synthesizing Polymer (A) The method for synthesizing the polymer (A) used in the present invention is preferably radical polymerization in solution. A polymerization initiator is used in normal radical polymerization. Polymerization initiators used for producing the polymer (A) include compounds that generate radicals by heat, such as azo initiators such as azobisisobutyronitrile and peroxide initiators such as benzoyl peroxide. agent can be used.

As the polymerization initiator, 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70) (trade name; Fujifilm Wako Pure Chemical Industries, Ltd.), 2,2′- Azobis (2,4-dimethylvaleronitrile) (V-65) (trade name; FUJIFILM Wako Pure Chemical Industries, Ltd.), 2,2′-azobis (isobutyronitrile) (V-60) (trade name) ; FUJIFILM Wako Pure Chemical Industries, Ltd.), 2,2'-azobis(2-methylbutyronitrile) (V-59) (trade name; FUJIFILM Wako Pure Chemical Industries, Ltd.), 2,2' -azobis [N- (2-propenyl) -2-methylpropionamide] (VF-096) (trade name; Fujifilm Wako Pure Chemical Industries, Ltd.), 2,2'-azobis (N-butyl-2- methyl propionamide) (VAm-110) (trade name; FUJIFILM Wako Pure Chemical Industries, Ltd.), dimethyl 2,2'-azobis(isobutyrate) (V-601) (trade name; FUJIFILM Wako Pure Chemical Industries, Ltd. ( Co., Ltd.), VPE-0201, VPE-0401, VPE-0601, VPS-1001 (all trade names; FUJIFILM Wako Pure Chemical Industries, Ltd.).

The weight average molecular weight of polymer (A) is preferably 1,000 to 200,000, more preferably 2,000 to 50,000. Within these ranges, the solubility, orientation ability and heat resistance are good.

The weight average molecular weight of the polymer (A) is a value in terms of polystyrene obtained by GPC method (column temperature: 35° C., flow rate: 1 ml/min). Polystyrene standards having weight average molecular weights of 645, 2590, 10290, 37600 and 285300 from Agilent Technologies' Polystyrene Calibration Kit PL2010-0102 were used. PLgel MIXED-D (Agilent Technologies, Inc.) was used as the column, and THF was used as the mobile phase. Also, the weight average molecular weights of the commercially available polymers described herein are catalog published values.

You may use a commercial item for a polymer (A). Specific examples include Marukalinker M (polyparahydroxystyrene, grade: S-2P, weight average molecular weight 4,000 to 6,000), Marukalinker M (polyparahydroxystyrene, grade: S-1P, weight average molecular weight 1,000 to 3,000) (all trade names; Maruzen Petrochemical Co., Ltd.). These compounds may be used alone or in combination of two or more. Also, a commercially available product and a synthetic product may be mixed.

2. Resin Composition for Liquid Crystal Alignment Film of the Present Invention The resin composition for liquid crystal alignment film of the present invention is a resin composition for liquid crystal alignment film containing a polymer (A) and a solvent (B).

The content of the polymer (A) (polymer solid matter) is preferably 2 to 35% by weight with respect to the total amount of the resin composition for liquid crystal alignment film. More preferably 5 to 25% by weight.

2-1. Solvent (B)
The solvent (B) used in the resin composition for liquid crystal alignment film is preferably a solvent capable of dissolving the polymer (A) and the like. Specific examples of the solvent (B) include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, acetone, 2-butanone, ethyl acetate, butyl acetate, Propyl acetate, butyl propionate, ethyl lactate, methyl hydroxyacetate, ethyl hydroxyacetate, butyl hydroxyacetate, methyl methoxyacetate, ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate, methyl 3-oxypropionate, 3 -ethyl hydroxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 2-hydroxypropionate, propyl 2-hydroxypropionate, 2- methyl methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, methyl 2-hydroxy-2-methylpropionate, 2-hydroxy-2- ethyl methyl propionate, methyl 2-methoxy-2-methylpropionate, ethyl 2-ethoxy-2-methylpropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, 2-oxobutane methyl acid, ethyl 2-oxobutanoate, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, ethylene glycol Monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate , cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, tetrahydrofuran, acetonitrile, dioxane, toluene, xylene, γ-butyrolactone, cyclohexanone, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, weight Polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol having an average molecular weight of 1,000 or less, and polypropylene glycol having a weight average molecular weight of 1,000 or less can be mentioned. The solvent may be one of these or a mixture of two or more thereof.

Among these, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether acetate, and It is more preferable to select and use one or more from propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether, and cyclopentanone.

The content of the solvent (B) is preferably 65 to 95% by weight with respect to the total amount of the resin composition for liquid crystal alignment film. More preferably 70 to 90% by weight.

When the polymer solution obtained in the synthesis of the polymer (A) is used in the resin composition for a liquid crystal alignment film without taking out the solid polymer from the polymer solution, the polymerization solvent contained in the polymer solution is also a solvent. Included in (B).

2-2. Additives Various additives can be added to the resin composition for a liquid crystal alignment film of the present invention in order to improve film physical properties such as flatness, scratch resistance, coating uniformity and adhesiveness. Examples of additives mainly include a cross-linking agent, a compound having a polymerizable double bond, a surfactant, an adhesion improver such as a silane coupling agent, and an antioxidant.

2-2-1. Cross-linking agent By adding a cross-linking agent, a cross-linking reaction occurs in the process of baking the coating film of the resin composition for liquid crystal alignment film, and a thin film having higher resistance to rubbing can be obtained, and the film generated in the rubbing process can be suppressed. In addition, higher heat resistance can be expected by cross-linking.

The cross-linking agent is not particularly limited as long as it is a compound having two or more functional groups in one molecule that react with the hydroxyl groups, which are cross-linkable functional groups on the side chains of the polymer (A).

Compounds that react with hydroxyl groups include acid anhydride-containing compounds, carboxylic acid-containing polymers, epoxy compounds, oxazoline compounds, and the like, and oxazoline compounds are preferred from the viewpoint of avoiding poor alignment.

Specific examples of compounds containing acid anhydrides and polymers containing carboxylic acids include aliphatic dicarboxylic acids such as maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and hexahydrotrimellitic anhydride. Acid anhydride; phthalic anhydride, aromatic polycarboxylic acid anhydride such as trimellitic anhydride, styrene-maleic anhydride copolymer; carboxylic acid-containing polymer ARUFON UC-3000, AR UFON UC-3090 ( All are trade names; Toagosei Co., Ltd.), Marproof MA-0215Z, Marproof MA-0217Z, and Marproof MA-0221Z (all trade names; NOF Corporation). These compounds may be used alone or in combination of two or more.

Specific examples of epoxy compounds include jER 828, jER 1004 and jER 1009 (all trade names; Mitsubishi Chemical Corporation) which are bisphenol A type epoxy compounds, jER 806 and jER 4005P which are bisphenol F type epoxy compounds (all Trade name; Mitsubishi Chemical Corporation), TECHMORE VG3101L (trade name; Printec Co., Ltd.) which is a glycidyl ether type epoxy compound, EHPE3150 (trade name; Daicel Co., Ltd.), EPPN-501H, EPPN-502H (any Also trade name; Nippon Kayaku Co., Ltd.), jER 1032H60 (trade name; Mitsubishi Chemical Co., Ltd.), Denacol EX-721 (trade name; Nagase ChemteX Corporation), which is a glycidyl ester type epoxy compound, 1, Diglycidyl 2-cyclohexanedicarboxylate (trade name; Tokyo Chemical Industry Co., Ltd.), jER YX4000, jER YX4000H, and jER YL6121H which are biphenyl-type epoxy compounds (all trade names; Mitsubishi Chemical Corporation), NC-3000, NC -3000-L, NC-3000-H, NC-3100 (all trade names; Nippon Kayaku Co., Ltd.), EPPN-201 which is a phenol novolac type epoxy compound (trade name; Nippon Kayaku Co., Ltd.), jER 152, jER 154 (both trade names; Mitsubishi Chemical Co., Ltd.), EOCN-102S, EOCN-103S, EOCN-104S, EOCN-1020 (both trade names; Nippon Kayaku ( Co., Ltd.), bisphenol A novolac type epoxy compounds jER 157S65 and jER 157S70 (both trade names; Mitsubishi Chemical Corporation), cycloaliphatic epoxy compounds Celloxide 2021P, Celloxide 3000, Epolead GT401 (both products name: Daicel Corporation), 1,3-bis[2-(3,4-epoxycyclohexyl)ethyl]tetramethyldisiloxane (trade name: Gelest Inc. Porated), which is an epoxy compound having a siloxane bond site, TSL9906 (trade name; Momentive Performance Materials Japan G.K.), COATOSIL MP200 (trade name; Momentive Performance Materials Japan G.K.), Composelan SQ506 (trade name; Arakawa Chemical Co., Ltd.), ES-1023 (trade name; Shin-Etsu Chemical Co., Ltd.), N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, which is a glycidylamine type epoxy compound, Sumepoxy ELM-434 (trade name Sumitomo Chemical Co., Ltd.), Sumiepoxy ELM-100 (trade name; Sumitomo Chemical Co., Ltd.), and 3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate. These compounds may be used alone or in combination of two or more.

A specific example of the oxazoline compound is 2,2'-(1,3-phenylene)bis-(2-oxazoline).

The amount of the cross-linking agent to be added is preferably 0.05 to 60 parts by weight, more preferably 0.05 to 30 parts by weight, per 100 parts by weight of the polymer (A).

2-2-2. Compound Having a Polymerizable Double Bond By adding a compound having a polymerizable double bond, it is expected that the planarizing ability is further enhanced. The compound having a polymerizable double bond is not particularly limited as long as it has two or more polymerizable double bonds per molecule.

In the compound having a polymerizable double bond, specific examples of compounds having two polymerizable double bonds per molecule include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth) ) acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, epichlorohydrin-modified ethylene glycol di(meth)acrylate, epichlorohydrin-modified diethylene glycol di(meth)acrylate, epichlorohydrin-modified triethylene glycol di(meth)acrylate, Epichlorohydrin-modified tetraethylene glycol di(meth)acrylate, epichlorohydrin-modified polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol Di(meth)acrylate, polypropylene glycol di(meth)acrylate, epichlorohydrin-modified propylene glycol di(meth)acrylate, epichlorohydrin-modified dipropylene glycol di(meth)acrylate, epichlorohydrin-modified tripropylene glycol di(meth)acrylate, epichlorohydrin-modified tetrapropylene Glycol di(meth)acrylate, epichlorohydrin-modified polypropylene glycol di(meth)acrylate, glycerol acrylate methacrylate, glycerol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, epichlorohydrin-modified 1,6-hexanediol di( meth)acrylate, methoxylated cyclohexyl di(meth)acrylate, neopentyl glycol di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, caprolactone-modified neopentylglycol hydroxypivalate di(meth)acrylate, stearic acid Modified pentaerythritol di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, bis[(meth)acryloxyneopentylglycol]adipate, bisphenol A di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, ethylene oxide-modified bisphenol F di(meth)acrylate, bisphenol S di(meth)acrylate, ethylene oxide-modified bisphenol S di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-butylene glycol di(meth) Acrylates, dicyclopentanyl diacrylate, ethylene oxide-modified phosphate di(meth)acrylate, caprolactone/ethylene oxide-modified phosphate di(meth)acrylate, epichlorohydrin-modified phthalate di(meth)acrylate, tetrabromobisphenol A di(meth)acrylate , triglycerol di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, and isocyanuric acid ethylene oxide-modified diacrylate.

Among the compounds having polymerizable double bonds, specific examples of compounds having 3 or more polymerizable double bonds per molecule include trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, Propylene oxide-modified trimethylolpropane tri(meth)acrylate, epichlorohydrin-modified trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, epichlorohydrin-modified glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, alkyl-modified di Pentaerythritol tri(meth)acrylate, ethylene oxide-modified phosphate tri(meth)acrylate, caprolactone/ethylene oxide-modified phosphate tri(meth)acrylate, caprolactone-modified tris[(meth)acryloxyethyl]isocyanurate, ditrimethylolpropane tetra(meth) ) acrylate, diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, and alkyl-modified dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate , dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, isocyanuric acid ethylene oxide-modified triacrylate, and carboxyl group-containing polyfunctional (meth)acrylate.

As the compound having a polymerizable double bond, the above compounds may be used alone, or two or more of them may be mixed and used.

From the viewpoint of flattening ability and scratch resistance, the compound having a polymerizable double bond includes ethylene oxide-modified bisphenol F di(meth)acrylate, ethylene oxide isocyanurate-modified diacrylate, ethylene oxide isocyanurate-modified triacrylate, and trimethylolpropane triacrylate. It is preferably selected from acrylates, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate and carboxyl group-containing polyfunctional (meth)acrylates.

The content of the compound having a polymerizable double bond is the polymer in the resin composition for a liquid crystal alignment film of the present invention, from the viewpoint of achieving a good balance between planarization ability, heat resistance, and alignment ability for liquid crystals and polymerizable liquid crystals. (A) 0.5 to 50 parts by weight per 100 parts by weight. It is preferably 0.5 to 10 parts by weight when more emphasis is placed on orientation ability.

2-2-3. Surfactant To the resin composition for a liquid crystal alignment film of the present invention, an anionic, cationic, nonionic, fluorine-based or silicon-based leveling agent/surfactant may be added in order to improve coating uniformity. good.

Specific examples of surfactants include Polyflow No. 75, Polyflow No. 90, Polyflow No. 95 (both trade names; Kyoeisha Chemical Co., Ltd.), Disperbyk-161, Disperbyk-162, Disperbyk-163, Disperbyk-164, Disperbyk-166, Disperbyk-170, Disperbyk-180, Disperbyk-181, Disperbyk-182, BYK-300, BYK-306, BYK-310, BYK-320, BYK-330, BYK-342, BYK-346, BYK-361N, BYK-3560, BYK-UV3500, BYK-UV3570 (all trade names: BYK-Chemie Japan Co., Ltd.), KP-341, KP-368, KP-96-50CS, KP-50-100CS (all trade names; Shin-Etsu Chemical Co., Ltd.), Surflon S611 (trade name; AGC Seimi Chemical ( Ltd.), Futergent 222F, Futergent 208G, Futergent 251, Futergent 710FL, Futergent 710FM, Futergent 710FS, Futergent 601AD, Futergent 650A, FTX-218 (all trade names; Neos Co., Ltd.) , Megafuck F-410, Megafuck F-430, Megafuck F-444, Megafuck F-472SF, Megafuck F-475, Megafuck F-477, Megafuck F-552, Megafuck F-553, Mega Fac F-554, Megafac F-555, Megafac F-556, Megafac F-558, Megafac F-559, Megafac R-94, Megafac RS-75, Megafac RS-72-K, Mega Fac RS-76-NS, Megafac DS-21 (both trade names; DIC Corporation), TEGO Twin 4000, TEGO Twin 4100, TEGO Flow 370, TEGO Flow 375, TEGO Glide 440, TEGO Glide 450, TEGO Rad 2200N (both trade names; Evonik Japan Co., Ltd.), fluoroalkylbenzenesulfonate, fluoroalkylcarboxylate, fluoroalkylpolyoxyethylene ether, fluoroalkylammonium iodide, fluoroalkylbetaine, fluoroalkylsulfonate, di Glycerin tetrakis (fluoroalkyl polyoxyethylene ether), fluoroalkyl tri methylammonium salt, fluoroalkylaminosulfonate, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether, Polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene laurate, polyoxyethylene oleate, polyoxyethylene stearate, polyoxyethylene laurylamine, sorbitan laurate, sorbitan palmitate, sorbitan stearate, sorbitan oleate ate, sorbitan fatty acid ester, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan oleate, polyoxyethylene naphthyl ether, alkyl benzene sulfonate, and alkyl diphenyl ether disulfonic acid Mention may be made of salt. One or more of these can be used. These compounds may be used alone or in combination of two or more.

Among these, from the viewpoint of high coating uniformity, BYK-306, BYK-342, BYK-346, BYK-361N, BYK-3560, KP-341, Surflon S611, Futergent 710FL, Futergent 710FM, Futergent 710FS , Futergent 650A, Megafac F-477, Megafac F-556, Megafac RS-72-K, Megafac DS-21, TEGO Twin 4000, TEGO Flow 375, Fluoroalkylbenzenesulfonate, Fluoroalkylcarboxylate , fluoroalkylpolyoxyethylene ethers, fluoroalkylsulfonates, fluoroalkyltrimethylammonium salts, and fluoroalkylaminosulfonates are preferred.

The content of the surfactant in the resin composition for a liquid crystal alignment film of the present invention is preferably 0.005 to 1% by weight based on the total amount of the composition.

2-2-4. Adhesion Improving Agent The resin composition for a liquid crystal alignment film of the present invention uses a silane-based, aluminum-based or titanate-based coupling agent or the like to improve the adhesion from the viewpoint of further improving the adhesion between the formed thin film and the substrate. It may further contain an agent.

Specific examples of adhesion improvers include 3-glycidyloxypropyldimethylethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Examples include silane-based coupling agents such as silane and 3-mercaptopropyltrimethoxysilane, aluminum-based coupling agents such as acetoalkoxyaluminum diisopropylate, and titanate-based coupling agents such as tetraisopropylbis(dioctylphosphite) titanate. be able to. These compounds may be used alone or in combination of two or more.

Among these, 3-glycidyloxypropyltrimethoxysilane is preferred.

The content of the adhesion improver is preferably 0.01 to 10% by weight based on the total amount of the resin composition for liquid crystal alignment film.

2-2-5. Antioxidant The resin composition for a liquid crystal alignment film of the present invention contains a phenol-based antioxidant, a phosphorus-based antioxidant, and sulfur from the viewpoint of improving transparency and preventing yellowing when the thin film is exposed to high temperatures. Antioxidants such as antioxidants and amine antioxidants may be further contained. Among these, phenolic antioxidants are preferred from the viewpoint of stability.

Specific examples of phenolic antioxidants include tert-butylhydroquinone, butylhydroxytoluene, ANTAGE SP (trade name; Kawaguchi Chemical Industry Co., Ltd.), pentaerythritol tetrakis[3-(3,5-di-tert-butyl- 4-hydroxyphenyl)propionate], thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], ethylenebis(oxyethylene)bis -(3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate, 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], Octyl-3,5-di-tert-butyl-4-hydroxy-hydro cinnamic acid, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl ) benzene, 4,6-bis(dodecylthiomethyl)-o-cresol, 4,6-bis(octylthiomethyl)-o-cresol (, 1,1,3-tris(2-methyl-4-hydroxy- 5-tert-butylphenyl)butane, 4,4′-butylidenebis(6-tert-butyl-3-methylphenol), 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert acrylate) -butyl-5-methylbenzyl)phenyl, 1,3,5-tris[[4-(1,1-dimethylethyl)-3-hydroxy-2,6-dimethylphenyl]methyl]-1,3,5- Triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine- 2,4,6-(1H,3H,5H)-trione, 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di- tert-butylphenol, 2,2′-dimethyl-2,2′-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropane-1,1′-diyl= Bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoa [items] can be mentioned. These compounds may be used alone or in combination of two or more.

Among these, from the viewpoint of thermal stability, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylene bis [3-(3,5-di-tert-butyl -4-hydroxyphenyl)propionate] is more preferred. From the viewpoint of solubility, butylhydroxytoluene and octyl-3,5-di-tert-butyl-4-hydroxy-hydrocalcinic acid are more preferable.

The content of the antioxidant is preferably 0.01 to 5.0 parts by weight, more preferably 0.05 to 2.0 parts by weight, per 100 parts by weight of the polymer (A).

2-3. Preparation of resin composition for liquid crystal alignment film It can be obtained by selecting and adding additives such as an activator, an adhesion improver, an antioxidant and other additives, and uniformly mixing and dissolving them.

2-4. Storage of Resin Composition for Liquid Crystal Alignment Film From the viewpoint of the stability of the composition over time, the resin composition for liquid crystal alignment film of the present invention is preferably stored in the range of -30°C to 25°C, preferably -20°C to -20°C. 10°C is more preferred.

3. Thin film obtained from the resin composition for liquid crystal alignment film The resin composition for liquid crystal alignment film prepared as described above is coated by conventionally known coating methods such as spin coating, roll coating, dipping and slit coating. can be applied to the substrate surface to form a coating film. Then, this coating film can be baked on a hot plate or in an oven to obtain a thin film. Firing is preferably carried out in two stages, ie, preliminary firing and final firing at a higher temperature after the preliminary firing. It is also preferable to add a step of partially removing the solvent by reducing the pressure before the calcination. Then, alignment ability is imparted by performing an alignment treatment using a rubbing method. Rubbing can be performed by a known method.

The calcination conditions vary depending on the type and blending ratio of each component, but are generally 1 to 15 minutes on a hot plate at 60 to 100° C. or in an oven. The main baking conditions vary depending on the type and blending ratio of each component, but are usually on a hot plate at 120 to 250° C. or in an oven for 5 to 90 minutes.

The thin film of the present invention has the ability to orient the driving liquid crystal and the polymerizable liquid crystal by the orientation treatment, and is excellent in transparency, heat resistance, and adhesion to the substrate. Therefore, it has the functions of a liquid crystal alignment film and a protective film, and can be used as a coating layer for both. Using this coating film layer, a liquid crystal display device or a solid-state imaging device can be manufactured.

In addition, the thin film of the present invention is also excellent in reworkability. Reworkability refers to the ability to dissolve or peel off defects such as pinholes with an alkaline solution or the like when defects such as pinholes are found in the coating film after coating or in the thin film after calcination in the production of an element. Since the substrate can be recovered and reused, materials with excellent reworkability are required.

EXAMPLES Next, the present invention will be specifically described by synthesis examples, examples and comparative examples, but the present invention is not limited by these examples.

For the abbreviations used in the examples, the corresponding compound names, trade names, etc. are described below.
<Monomer for Polymer (A) or Comparative Polymer>
4-VP: 4-vinylphenol MS: methylstyrene AS: 4-aminostyrene VB: 4-vinylbiphenyl VN: vinylnaphthalene VKOH: 1-(4-hydroxyphenyl)-1-propanone HQMA: 4-hydroxyphenylmethacrylate PEMA : 2-Phenoxyethyl methacrylate <Polymer (A)>
S-2P: Marukalinker M (polyparahydroxystyrene, grade: S-2P) (trade name; Maruzen Petrochemical Co., Ltd.)
S-1P: Marukalinker M (polyparahydroxystyrene, grade: S-1P) (trade name; Maruzen Petrochemical Co., Ltd.)
<Polymerization initiator>
V-601: dimethyl 2,2'-azobis(isobutyrate)
<Solvent>
CP: Cyclopentanone PGMEA: Propylene glycol monomethyl ether acetate 3MP: Methyl 3-methoxypropionate EDM: Diethylene glycol ethyl methyl ether BCS: Ethylene glycol monobutyl ether <Additive>
<Crosslinking agent>
1,3-PBO: 2,2′-(1,3-phenylene)bis-(2-oxazoline)
CEL2021P: 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate <Compound with a polymerizable double bond>
M208: Aronix M-208 (ethylene oxide-modified bisphenol F diacrylate) (trade name; Toagosei Co., Ltd.)
<Antioxidant>
BHT: Butyl hydroxytoluene A-SP: ANTAGE SP (trade name; Kawaguchi Chemical Industry Co., Ltd.)
<Surfactant>
F-477: Megafac F-477 (trade name; DIC Corporation)
BYK-3560: BYK-3560 (trade name; BYK-Chemie Japan Co., Ltd.)
BYK-361N: BYK-361N (trade name; BYK-Chemie Japan Co., Ltd.)
DS-21: Megafac DS-21 (trade name; DIC Corporation)
TEGO Flow 375: TEGO Flow 375 (trade name; Evonik Japan Co., Ltd.)

Abbreviations of measurement items in the examples are shown below.
Mw: weight average molecular weight Mn: number average molecular weight

The weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by GPC method and converted to polystyrene. The obtained polymer solution was diluted with a phosphoric acid-DMF mixed solution (phosphoric acid/DMF=0.6/100: weight ratio) so that the polymer solid content concentration was about 1% by weight, and used for measurement. The equipment and analysis conditions used are described in the next paragraph. As standard polystyrene, TSK standard polystyrene manufactured by Tosoh Corporation was used.

Next, the apparatus and analysis conditions used in the examples are shown.
<GPC>
Apparatus: Waters 2695 separation module/2414 differential refractometer Solvent: phosphoric acid-DMF mixed solution (phosphoric acid/DMF=0.6/100 weight ratio)
Flow rate: 0.40 mL/min
Column temperature: 50°C
Column used: HSPgel RT MB-M manufactured by Waters
Standard sample for calibration curve: TSK standard polystyrene <spinner> manufactured by Tosoh Corporation
Apparatus: MS-A150 manufactured by Mikasa Co., Ltd.
<Film thickness measurement>
Apparatus: KLA-Tencor Japan Co., Ltd. stylus type film thickness gauge P-16 (trade name)
Measurement method: Measured at three locations, and the average value was taken as the film thickness.
<Transmittance measurement>
Apparatus: UV-visible spectrophotometer V-670 (trade name) manufactured by JASCO Corporation

[Synthesis of polymer (A)]
[Synthesis Example 1 (A1)]
A four-necked flask equipped with a stirrer was charged with dehydrated and purified CP and 4-VP in the following weights, and further with polymerization initiator V-601 in the following weights, followed by stirring at 90° C. for 2 hours under a stream of dry nitrogen.
CP 27.80g
4-VP 10.00g
V-601 1.90g

After the reaction, the solution was cooled to 25° C. to obtain a 30% by weight solution of polymer (A-1). A part of the solution was sampled and the weight average molecular weight was measured by GPC analysis. As a result, the weight average molecular weight of the obtained polymer (A-1) was 5,400. This solution was used for preparation of the resin composition for liquid crystal aligning films as it was.

[Synthesis Examples 2 and 3, Comparative Synthesis Examples 1 to 7]
According to the method of Synthesis Example 1, each raw material in the weight shown in Table 1 was charged to synthesize a 30% by weight solution containing each polymer. Table 1 shows the weight average molecular weight of the obtained polymer. In Comparative Synthesis Example 2 (A'-2), the solution gelled and a transparent and uniform polymer solution could not be obtained. The obtained polymer was used in the form of a polymer solution for preparing a resin composition for a liquid crystal alignment film.

Table 1

<Preparation of Resin Composition for Liquid Crystal Alignment Film>
Using the commercially available products and the polymers obtained in Synthesis Examples and Comparative Synthesis Examples, resin compositions for liquid crystal alignment films were prepared as shown below.

[Example 1]
After mixing and dissolving S-2P (2.00 g), PGMEA (11.30 g), and F-477 (0.002 g), the composition was filtered through a fluororesin membrane filter (pore size: 0.2 μm). got 1.

Alignment ability, transparency, heat resistance, reworkability, and adhesion of the prepared composition 1 were evaluated as follows. The evaluation results are shown in Table 2-1.

<<Orientation ability evaluation>>
<Preparation of Liquid Crystal Composition Solution for Alignment Ability Evaluation>
A polymerizable liquid crystal composition solution used for evaluation was prepared in advance as follows.
20.00 g of Paliocolor LC242 (trade name; BASF Japan Ltd.), 1.00 g of IRGACURE907 (trade name; BASF Japan Ltd.), 0.020 g of BYK-361N, and toluene as a solvent are added. is adjusted to 85% by weight of the total, and mixed and dissolved uniformly. This composition is designated as a polymerizable liquid crystal composition solution (PLC-1).

<Preparation of thin film for orientation ability evaluation>
A resin composition for a liquid crystal alignment film was coated on a glass substrate "EAGLE XG" manufactured by Corning Corporation as a base (trade name, thickness 0) by adjusting the number of revolutions so that the film thickness was about 1.5 μm with a spin coater. .7 mm). Next, the substrate coated with the composition was dried on a hot plate at 60°C for 3 minutes, and then baked in an oven at 230°C for 30 minutes. The thin film thus obtained was subjected to a rubbing treatment using a rubbing apparatus equipped with a rayon rubbing cloth YA-18-R (trade name; Yoshikawa Kako Co., Ltd.). The rubbing speed is 60 mm/sec and the roller rotation speed is 1,000 rpm. Next, a polymerizable liquid crystal composition solution (PLC-1) was applied onto the substrate with a spin coater, dried on a hot plate at 80° C. for 1 minute, and irradiated with 300 mJ/cm ² using an ultra-high pressure mercury lamp. gone. The exposure amount is a value measured using a 365 nm illuminance meter without using a cut filter and a polarizing plate. Further, by post-baking in an oven at 230° C. for 30 minutes, a test substrate having a thin film for evaluation of orientation capability was prepared, and orientation capability was evaluated.

<Orientation ability evaluation and measurement>
The obtained test substrate having the thin film for evaluation of alignment ability was sandwiched between two linear polarizing plates in a crossed Nicols state in a direction parallel to the polarizing plates, and the test substrate was held while maintaining a direction parallel to the polarizing plates. It was observed by rotating it and illuminating it with a backlight from below. After confirming that a dark state was observed throughout one rotation of the test substrate, the test substrate was set in a phase difference measuring device (OPTIPRO; product name; Shintech Co., Ltd.) to measure the phase difference. The angle of incidence was 0° in the direction perpendicular to the substrate surface (frontal direction), and the phase difference was measured by changing the angle from −45° to +45° at intervals of 5°. As a result of plotting the incident angle on the horizontal axis and the phase difference on the vertical axis, a downwardly convex curve was obtained, confirming the vertical alignment. ◯ is indicated in the alignment ability (perpendicular) column of Table 2-1. The plotted results are shown in FIG.

In the following examples and comparative examples, when a dark state was observed in the first observation and a downwardly convex curve similar to that in FIG. 〇). In addition, when the bright state was observed throughout one rotation in the first observation, it means that the liquid crystal molecules were not aligned, and was marked with x in the alignment ability (perpendicular) column.

<Transparency evaluation, transmittance measurement>
The resin composition for a liquid crystal alignment film was applied on a Corning glass substrate EAGLE XG by a spin coater while adjusting the number of revolutions so that the film thickness was about 1.5 μm. Next, the substrate coated with the composition was dried on a hot plate at 60°C for 3 minutes and then baked in an oven at 230°C for 30 minutes to prepare a test substrate having a thin film for transmittance measurement. Transmittance measurements were made. The transmittance was evaluated for the value at a transmission wavelength of 400 nm. At a transmission wavelength of 400 nm, a transmittance of 90% or more was rated as ◯, and a transmittance of less than 90% was rated as x.

<Heat resistance measurement>
A thin film was prepared according to the method for preparing a thin film for transmittance measurement described above. A thin film piece or powder was cut out from the obtained glass substrate with the thin film with a cutter, and the glass transition point was measured using a differential scanning calorimeter (Hitachi High-Tech Science Co., Ltd.). When the glass transition point was 100°C or higher, it was evaluated as ◯, and when it was lower than 100°C, it was evaluated as x.

<Reworkability evaluation>
The resin composition for a liquid crystal alignment film was applied on a Corning glass substrate EAGLE XG by a spin coater while adjusting the number of revolutions so that the film thickness was about 1.5 μm. Next, the substrate coated with the composition was dried on a hot plate at 60° C. for 15 minutes, and then immersed in a 5% sodium hydroxide aqueous solution at 25° C. for 10 minutes. The substrate was visually observed after immersion, and the case where no thin film remained on the substrate was evaluated as 〇 (thin film completely dissolved), and the case where the thin film remained was evaluated as × (thin film was not completely dissolved). .

<Adhesion evaluation>
A thin film was prepared according to the method for preparing a thin film for transmittance measurement described above. The obtained glass substrate with a thin film was evaluated by a checkerboard peeling test (cross-cut test). For the evaluation, the number of grids remaining after the tape was peeled off was counted among 100 grids of 1 mm square. The tape used was model number 610 manufactured by 3M. When the remaining number/100 was 100 to 90/100, it was evaluated as ◯; when it was 89 to 50/100, it was evaluated as Δ;

[Examples 2 to 19, Comparative Examples 1 to 7]
Compositions 2 to 19 and Comparative Composition 1 were prepared according to the method of Example 1, except that the polymer, solvent, additive, and amount charged thereof were changed as shown in Tables 2-1 to 2-4. ~7 was obtained. In Examples 17 to 19, the charged amount described in the column of polymer (A) is the charged amount of the polymer solution. In calculating the solids concentration of the composition, 30% by weight (2.10 g) of this is taken as polymer solids and 70% by weight (4.90 g) as solvent (B). The same applies to Comparative Examples 1-7.

Each evaluation was performed according to Example 1 for each of the obtained compositions. Evaluation results are shown in Tables 2-1 to 2-4.

Table 2-1

Table 2-2

Table 2-3

Table 2-4

As shown in Tables 2-1 to 2-3, all of the thin films obtained in Examples 1 to 19 had excellent alignment ability for polymerizable liquid crystals, excellent transparency, heat resistance, reworkability, and adhesion to the substrate. showed that. In comparison, the thin films of Comparative Examples 1 and 3 to 6 in Tables 2-4 did not show orientation ability, and Comparative Example 7 showed orientation ability, but the heat resistance and substrate required for the protective film It was not possible to satisfy the characteristics such as adhesion to Thus, the thin film obtained from the composition of the comparative example could not satisfy all the requirements at the same time. Here, in Comparative Example 2, each evaluation could not be performed because the polymer solution (A'-2) used was in the form of a white gel, and a uniform resin composition for a liquid crystal alignment film could not be obtained.

According to the present invention, it is possible to provide a highly transparent thin film having alignment ability, heat resistance, and adhesion to a substrate. It can be used as a thin film having the functions of a liquid crystal alignment film and a protective film.

Claims (7)

A resin composition for a liquid crystal alignment film comprising a polymer (A) and a solvent (B), wherein the repeating unit in the polymer (A) has a structure represented by formula (1). .

In formula (1), R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently H, CH ₃ , OCH ₃ or OH, R ¹ , R ² , R ³ , R ⁴ and R At least one of ⁵ is OH. 2. The resin composition for a liquid crystal alignment film according to claim 1, wherein in formula (1), ^R3 is OH. 3. The resin composition for a liquid crystal alignment film according to claim 2, wherein ^R1 , ^R2 , ^R4 and ^R5 in formula (1) are H. Any one of claims 1 to 3, further comprising at least one additive selected from the group consisting of a cross-linking agent, a compound having a polymerizable double bond, a surfactant, an adhesion improver and an antioxidant. 2. The resin composition for a liquid crystal alignment film according to item 1. 5. The liquid crystal according to claim 4, comprising a cross-linking agent and further comprising at least one additive selected from the group consisting of a compound having a polymerizable double bond, a surfactant, an adhesion improver and an antioxidant. A resin composition for an alignment film. A thin film obtained from the resin composition for a liquid crystal alignment film according to any one of claims 1 to 5. A liquid crystal display device comprising the thin film according to claim 6 .

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