Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element using the same

Abstract

To provide a liquid crystal alignment film which can be used to produce a liquid crystal display element that offers good contrast and afterimage characteristics and features fast relaxation of accumulated charge.SOLUTION: By using at least one of a diamine represented by the formula (1) and tetracarboxylic dianhydrides represented by a specific general structural formula in the same polymer, a liquid crystal alignment film with high liquid crystal alignability can be produced. Use of such a crystal alignment film allows for producing a liquid crystal display element that offers good contrast and afterimage characteristics and exhibits fast relaxation of accumulated charge. In the formula (1), R1 and R2 each independently represent a hydrogen atom or the like, X each independently represent a halogen atom or the like, and n represents an integer of 0 to 4.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element using the same. More specifically, the present invention relates to a liquid crystal alignment agent for forming a photo-alignment type liquid crystal alignment film (hereinafter, sometimes referred to as a "photo-alignment film"), a photo-alignment type liquid crystal alignment film formed using the liquid crystal alignment agent and a manufacturing method thereof, and a liquid crystal display element having the liquid crystal alignment film. Furthermore, the present invention relates to a polymer such as polyamic acid used in the liquid crystal alignment agent, and tetracarboxylic dianhydrides and diamines that are raw materials thereof.

[0002] Liquid crystal display elements are known to have various driving methods, such as TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, IPS (In-Plane Switching) mode, FFS (Fringe Field Switching) mode, and VA (Vertical Alignment) mode. These liquid crystal display elements are applied to image display devices of various electronic devices, such as televisions and mobile phones, and development is being carried out with the aim of further improving the display quality. Specifically, the performance of liquid crystal display elements is improved not only by improving the driving method and element structure, but also by the components used in the elements. Among the components used in liquid crystal display elements, the liquid crystal alignment film is one of the important materials related to the display quality, and research on this liquid crystal alignment film is being actively carried out in order to meet the demand for higher quality liquid crystal display elements.

[0003] Here, the liquid crystal alignment film is provided on a pair of substrates provided on both sides of the liquid crystal layer of the liquid crystal display element in contact with the liquid crystal layer, and has the function of orienting the liquid crystal molecules constituting the liquid crystal layer with a certain regularity relative to the substrates. By using a liquid crystal alignment film with high liquid crystal alignment properties, a liquid crystal display element with high contrast and improved afterimage characteristics can be realized (see, for example, Patent Documents 1 and 2).

[0004] Currently, solutions (varnishes) in which polyamic acid, soluble polyimide, or polyamic acid ester is dissolved in an organic solvent are mainly used to form such liquid crystal alignment films. To form liquid crystal alignment films using these varnishes, the varnish is applied to a substrate, and the coating is solidified by heating or the like to form a polyimide-based liquid crystal alignment film, and an alignment treatment suitable for the above-mentioned display mode is performed as necessary. As alignment treatment methods, there are a rubbing method in which the surface of the alignment film is rubbed with a cloth or the like to align the direction of the polymer molecules, and a photoalignment method in which the alignment film is irradiated with linearly polarized ultraviolet light to cause photochemical changes such as photoisomerization, dimerization, and phototransition in the polymer molecules to impart anisotropy to the film. Of these, the photoalignment method has the advantages of being more uniform in alignment than the rubbing method, not scratching the film because it is a non-contact alignment treatment method, and reducing causes of display defects in liquid crystal display elements such as dust generation and static electricity. As one of the above-mentioned photo-alignment methods, a decomposition-type photo-alignment method is known. In this decomposition-type photo-alignment method, for example, a polyimide film is irradiated with polarized ultraviolet light, and anisotropic decomposition is caused by utilizing the polarization direction dependency of ultraviolet light absorption of the molecular structure, and liquid crystal is aligned by the polyimide that remains undecomposed (for example, see Patent Document 3). As another photoalignment method, it has been reported that a polyamic acid or its derivative synthesized by using a diamine compound having a specific cyclopropane structure as a diamine monomer is used as a liquid crystal alignment agent to obtain a liquid crystal alignment film with high liquid crystal alignment properties, and that the use of this liquid crystal alignment film can be used to realize a liquid crystal display element exhibiting high contrast (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-197999 A [Patent Document 2] International Publication No. 2013 / 157463 [Patent Document 3] JP 2007-248637 A [Patent Document 4] Patent No. 6907424 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been an increasing demand for high-quality liquid crystal display elements, which are required to have good contrast, afterimage characteristics, and rapid relaxation of accumulated charges. As mentioned above, a liquid crystal alignment film with high liquid crystal alignment properties is required to realize a liquid crystal display element with high contrast and good afterimage characteristics. In addition, if electric charges are accumulated due to a direct current voltage applied to a liquid crystal display element, burn-in occurs, resulting in a decrease in display quality. Therefore, a liquid crystal alignment film that can quickly relieve accumulated electric charges is required.

[0007] Therefore, the inventors have conducted intensive research with the objectives of providing a liquid crystal alignment film capable of forming a liquid crystal display element having good contrast and afterimage characteristics and rapid relaxation of accumulated charge, and of providing a liquid crystal alignment agent capable of forming such a liquid crystal alignment film. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the inventors have found that a liquid crystal alignment film with high liquid crystal alignment properties can be obtained by using a diamine represented by formula (1) and at least one of tetracarboxylic dianhydrides represented by formula (2) or formula (3) in the same polymer, and that the use of this liquid crystal alignment film can form a liquid crystal display element that has good contrast and afterimage characteristics and quickly relaxes accumulated charges, thereby completing the present invention. The present invention includes the following configurations.

[0009] [1] A liquid crystal aligning agent comprising at least one polymer and a solvent, wherein at least one of the polymers is a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine, A liquid crystal aligning agent, wherein the diamines include at least one compound represented by formula (1), and the tetracarboxylic dianhydrides include at least one compound selected from the group consisting of compounds represented by formula (2) or (3) and derivative compounds thereof. TIFF0007647448000001.tif2679 In formula (1), R 1 and R 2 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; R 1 and R 2 may be taken together to form an optionally substituted methylene group, Each X is independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; n represents an integer from 0 to 4; TIFF0007647448000002.tif3969 In formula (2) and formula (3), R 3 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and in formula (3), W is an alkylene group having 1 to 12 carbon atoms, and one or more non-adjacent -(CH2)2- of the alkylene group may be replaced with either -O- or -NH-, In formula (1), formula (2) and formula (3), a group that is not fixed to any of the carbon atoms constituting a ring can be bonded to any available carbon atom in the ring. [2] The liquid crystal aligning agent according to [1], wherein the compound represented by formula (1) is a compound represented by formula (1-2): TIFF0007647448000003.tif2072 In formula (1-2), R 1 and R 2are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; R 1 and R 2 may be joined together to form an optionally substituted methylene group. [3] The liquid crystal aligning agent according to [1] or [2], wherein in the formula (1) or formula (1-2), the two esters are arranged in a trans configuration on the cyclopropane ring. [4] The liquid crystal aligning agent according to any one of [1] to [3], wherein the tetracarboxylic dianhydrides include at least one compound selected from the group consisting of compounds represented by formula (2-1) or formula (3-1) and derivative compounds thereof: TIFF0007647448000004.tif4694 In formula (3-1), m is an integer of 1 to 8. [5] The liquid crystal aligning agent according to any one of [1] to [4], wherein the diamines include a compound represented by formula (4): TIFF0007647448000005.tif1169 In formula (4), R 4 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms; and k represents an integer of 1 to 6. [6] The liquid crystal aligning agent according to [5], wherein the compound represented by formula (4) is a compound represented by formula (4-1): TIFF0007647448000006.tif1172 [7] The liquid crystal aligning agent according to any one of [1] to [6], further comprising an additive. [8] A liquid crystal alignment film formed from the liquid crystal aligning agent according to any one of [1] to [7]. [9] A liquid crystal element having the liquid crystal alignment film according to [8].

[10] A method for producing a liquid crystal alignment film, comprising the steps of applying the liquid crystal aligning agent according to any one of [1] to [7] to a substrate, and irradiating the coating with polarized ultraviolet light. Effect of the Invention

[0010] By using the liquid crystal aligning agent of the present invention, a liquid crystal alignment film with high liquid crystal alignment properties can be obtained. In addition, by using this liquid crystal alignment film, a liquid crystal display device with excellent afterimage characteristics and contrast and rapid relaxation of accumulated charges can be realized. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment or a specific example, but the present invention is not limited to such an embodiment. As one embodiment of the present invention, the liquid crystal aligning agent of the present invention can be used as a liquid crystal aligning agent for photo-alignment by using a compound having a photoreactive structure. The liquid crystal aligning agent for photo-alignment is a liquid crystal aligning agent that can be given anisotropy by forming a film of the liquid crystal aligning agent on a substrate and irradiating it with polarized ultraviolet light, and is sometimes simply referred to as a "liquid crystal aligning agent" in this specification. In addition, an alignment film formed from a liquid crystal aligning agent for photo-alignment may be referred to as a photo-alignment film or simply as an alignment film. In addition, in the present invention, "tetracarboxylic dianhydrides" refers to tetracarboxylic dianhydrides, tetracarboxylic diesters, or tetracarboxylic diester dihalides. "Derived compounds of tetracarboxylic dianhydrides" or simply "derived compounds" refers to tetracarboxylic diesters or tetracarboxylic diester dihalides. In addition, in the present invention, diamines and dihydrazides are sometimes referred to as "diamines".

[0012] <Diamine compound represented by formula (1)> The liquid crystal aligning agent of the present invention is a liquid crystal aligning agent containing a polymer obtained by reacting tetracarboxylic dianhydrides with diamines, and the diamines contain at least one photosensitive diamine selected from the compounds represented by the following formula (1):

[0013] TIFF0007647448000007.tif2892 In formula (1), R 1 and R 2 R are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 1 and R 2 may be joined together to form an optionally substituted methylene group. Each X is independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and n is an integer from 0 to 4. In formula (1), a group that is not fixedly bonded to any carbon atom constituting the ring indicates that it can be bonded to any available carbon atom in the ring.

[0014] Below, R of each formula 1 , R 2 The substituents of halogen atoms, alkyl groups having 1 to 6 carbon atoms, haloalkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms and methylene groups in X will be described below. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The alkyl group having 1 to 6 carbon atoms may be linear, branched, or cyclic. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylbutyl group, a 1-ethylpropyl group, a hexyl group, an isohexyl group, a 1-methylpentyl group, a 1-ethylbutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the haloalkyl group having 1 to 6 carbon atoms include the above-mentioned alkyl group having 1 to 6 carbon atoms in which any number of hydrogen atoms at any position are substituted with halogen atoms. Specific examples of halogen atoms include R 1 , R 2and specific examples of halogen atoms in X can be referred to. The number of halogen atoms in the haloalkyl group is preferably 1 to 5, more preferably 1 to 4, and further preferably 1 to 3. Specific examples of the haloalkyl group include a difluoromethyl group, a trifluoromethyl group, a 1,1-difluoroethyl group, a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 3-fluoropropyl group, a chloromethyl group, a dichloromethyl group, and a trichloromethyl group. The alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propyl group, an isopropyloxy group, a butyloxy group, an isobutyloxy group, a sec-butyloxy group, a tert-butyloxy group, a pentyloxy group, a isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, a 1-methylbutyloxy group, a 1-ethylpropyloxy group, a hexyloxy group, a isohexyloxy group, a 1-methylpentyloxy group, a 1-ethylbutyloxy group, a cyclopentyloxy group, and a cyclohexyloxy group. Examples of the substituent on the methylene group include a halogen atom such as a fluorine atom or a chlorine atom, an alkyl group which may be substituted with a halogen atom such as a fluorine atom or a chlorine atom or an alkoxy group having 1 to 4 carbon atoms, and an aryl group which may be substituted with a halogen atom such as a fluorine atom or a chlorine atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.

[0015] A preferred example of the diamine compound represented by formula (1) is a compound represented by the following formula (1-1). TIFF0007647448000008.tif2694In equation (1-1), R 1 , R 2 , X and n are R in formula (1). 1 , R 2, X and n are synonymous. The definition of the group not fixed to any of the carbon atoms constituting the ring is the same as that of formula (1). The polymer synthesized using the diamine compound represented by formula (1-1) has high linearity because the amino group is located at the para position relative to the ester, and the liquid crystal alignment film using the polymer can exhibit high anisotropy.

[0016] Among the diamine compounds represented by formula (1-1), the diamine compounds represented by the following formula (1-2) are useful from the viewpoint of the ease of obtaining raw materials for their production.

[0017] TIFF0007647448000009.tif2384 R in equation (1-2) 1 and R 2 is R in formula (1). 1 and R 2 is synonymous with.

[0018] Among the compounds represented by formula (1), those in which the two esters on the cyclopropane ring are in a trans configuration are preferred. Such compounds have high linearity and contribute to high anisotropy of the liquid crystal alignment film. Taking formula (1-2) as an example, the compound represented by formula (1-2A) and its enantiomer are preferred. A mixture of the compound represented by formula (1-A) and its enantiomer may be used as a raw material for the polymer, or they may be mixed in equal amounts to be used as a raw material for the polymer as a racemate.

[0019] TIFF0007647448000010.tif2184 R in formula (1-2A) 1 and R 2 is R in formula (1). 1 and R 2 is synonymous with.

[0020] Specific examples of the compound represented by formula (1) include the following compounds. TIFF0007647448000011.tif186148

[0021] For example, compounds with the same numbers a and b are in an enantiomeric relationship, such as the relationship between the compound of formula (1-2-1a) and the compound (1-2-1b). In this specification, a mixture of compounds that are in an enantiomeric relationship with each other may be referred to as a "diamine isomer mixture". Such a diamine isomer mixture can also be used as the diamine compound (1) in the raw material composition. Among these, the compounds of formula (1-2-1a) and formula (1-2-1b) are preferred in terms of the ease of obtaining raw materials and properties.

[0022] <Tetracarboxylic acid dianhydrides represented by formula (2) or formula (3)> The liquid crystal aligning agent of the present invention is a liquid crystal aligning agent containing a polymer obtained by reacting tetracarboxylic dianhydrides with diamines, and contains at least one selected from the group consisting of compounds represented by formula (2) or formula (3) and derivative compounds thereof as tetracarboxylic dianhydrides. In this specification, the compounds represented by formula (2) or formula (3) and derivative compounds thereof may be referred to as "tetracarboxylic dianhydrides represented by formula (2) or formula (3)". TIFF0007647448000012.tif3969 In formula (2) and formula (3), R 3 are each independently a hydrogen atom or a substituted or unsubstituted alkyl having 1 to 6 carbon atoms; in formula (3), W is an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent -(CH2)2- of the alkylene may be replaced with either -O- or -NH-; and in formulas (2) and (3), a group that is not fixedly bonded to any carbon atom constituting a ring can be bonded to any available carbon atom in the ring.

[0023] Below, R in Equation (2) and Equation (3) 3 The substituted or unsubstituted alkyl group having 1 to 6 carbon atoms in the above formula (I) will be described. The alkyl group having 1 to 6 carbon atoms may be linear, branched, or cyclic. Specific examples of the unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylbutyl group, a 1-ethylpropyl group, a hexyl group, an isohexyl group, a 1-methylpentyl group, a 1-ethylbutyl group, a cyclopentyl group, and a cyclohexyl group. The substituted alkyl group having 1 to 6 carbon atoms includes the above alkyl group having 1 to 6 carbon atoms in which any number of hydrogen atoms at any position are substituted with halogen atoms. Specific examples of halogen atoms include R 1 , R 2 and specific examples of halogen atoms in X can be referred to. The number of halogen atoms in the haloalkyl group is preferably 1 to 5, more preferably 1 to 4, and further preferably 1 to 3. Specific examples of the haloalkyl group include a difluoromethyl group, a trifluoromethyl group, a 1,1-difluoroethyl group, a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 3-fluoropropyl group, a chloromethyl group, a dichloromethyl group, and a trichloromethyl group.

[0024] Examples of the compound represented by formula (2) or formula (3) include compounds represented by the following formula (2-1) or formula (3-1). TIFF0007647448000013.tif4694 In formula (3-1), m is an integer from 1 to 8.

[0025] <Diamines represented by formula (4)> The raw material for the polymer of the present invention may further contain a diamine represented by formula (4), which can further improve the relaxation speed of the accumulated charge. TIFF0007647448000014.tif1169 In formula (4), R4 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms; and k represents an integer of 1 to 6.

[0026] An example of the compound represented by formula (4) is a compound represented by the following formula (4-1). TIFF0007647448000015.tif1172

[0027] <Method for producing the compounds represented by formula (1), formula (2) and formula (3)> For the production method of the compound represented by formula (1) of the present invention, reference can be made to Patent Document 4. For the production methods of the compound represented by formula (2) and the compound represented by formula (3) of the present invention, reference can be made to Polymer, 2008, 49, 1191-1198.

[0028] <Polymer> The polymer of the present invention used in the liquid crystal aligning agent of the present invention is at least one selected from the group consisting of polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide, obtained by using at least one diamine represented by formula (1) and at least one tetracarboxylic dianhydride represented by formula (2) or formula (3) as raw materials. In this specification, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide are sometimes referred to as "polyamic acid derivatives".

[0029] The polyamic acid and the polyamic acid derivatives will be described in detail below.

[0030] Here, the polyamic acid is, for example, a polymer synthesized by a polymerization reaction between a tetracarboxylic dianhydride represented by formula (AN) and a diamine represented by formula (DI), and has a constitutional unit represented by formula (PAA). When a liquid crystal alignment agent containing a polyamic acid is heated and baked in the process of forming a liquid crystal alignment film, the polyamic acid is imidized, and a polyimide liquid crystal alignment film having a constitutional unit represented by formula (PI) can be formed. TIFF0007647448000016.tif36140 TIFF0007647448000017.tif3659

[0031] In formula (AN), formula (PAA), and formula (PI), X 1 is a tetravalent organic group. In formula (DI), formula (PAA), and formula (PI), X 2 is a divalent organic group. 1 For the preferred range and specific examples of X, reference can be made to the corresponding structures of the tetracarboxylic dianhydrides described in the formula (1), formula (2), and the other tetracarboxylic dianhydrides section below. 2 For the preferred range and specific examples, reference can be made to the diamines represented by the following formula (4) and the corresponding structures of the diamines or dihydrazides described in the section on other diamines below.

[0032] The polyamic acid derivative is a polymer whose characteristics are modified by replacing a part of the polyamic acid with another atom or atomic group, and is preferably one whose solubility in a solvent used for a liquid crystal alignment agent is increased. Specific examples of such polyamic acid derivatives include 1) polyimides in which all amino groups and carboxyl groups of a polyamic acid are subjected to a dehydration ring-closing reaction, 2) partial polyimides in which a part of the polyamic acid is subjected to a dehydration ring-closing reaction, 3) polyamic acid esters in which the carboxyl groups of a polyamic acid are converted into esters, 4) polyamic acid-polyamide copolymers obtained by replacing a part of the acid dianhydride contained in a tetracarboxylic dianhydride compound with an organic dicarboxylic acid and reacting the resulting mixture, and 5) polyamideimides in which a part or all of the polyamic acid-polyamide copolymer is subjected to a dehydration ring-closing reaction. Among these derivatives, for example, polyimides having a constitutional unit represented by the above formula (PI) can be mentioned, and polyamic acid esters having a constitutional unit represented by the following formula (PAE) can be mentioned. TIFF0007647448000018.tif4661 In the formula (PAE), X 1 is a tetravalent organic group, and X 2 is a divalent organic group, and each Y is independently an alkyl group. 1 , X 2 The preferred range and specific examples of X in formula (PAA) are 1 , X 2 Y is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tertiary butyl group.

[0033] The raw material composition used in the synthesis of the polyamic acid may contain one type of tetracarboxylic dianhydrides and one or more types of diamines.

[0034] When the polyamic acid of the present invention is converted into a polyamic acid derivative, a polyimide, the polyimide can be obtained by imidizing the obtained polyamic acid solution together with an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride as a dehydrating agent, and a tertiary amine such as triethylamine, pyridine, or collidine as a dehydration ring-closing catalyst at a temperature of 20 to 150° C. Alternatively, the polyamic acid can be precipitated from the obtained polyamic acid solution using a large amount of a poor solvent (an alcohol-based solvent such as methanol, ethanol, or isopropanol, or a glycol-based solvent), and the precipitated polyamic acid can be imidized in a solvent such as toluene or xylene together with the above-mentioned dehydrating agent and dehydration ring-closing catalyst at a temperature of 20 to 150° C. to obtain a polyimide.

[0035] In the imidization reaction, the ratio of the dehydrating agent to the dehydration ring-closing catalyst is preferably 0.1 to 10 (molar ratio). The total amount of the dehydrating agent and the dehydration ring-closing catalyst used is preferably 1.5 to 10 times by mol relative to the total molar amount of the tetracarboxylic dianhydrides used in the synthesis of the polyamic acid. The degree of imidization can be controlled by adjusting the amount of the dehydrating agent and catalyst used in the imidization reaction, the reaction temperature, and the reaction time, thereby obtaining a partial polyimide in which only a part of the polyamic acid is imidized. The obtained polyimide can be separated from the solvent used in the reaction and redissolved in another solvent to be used as a liquid crystal alignment agent, or it can be used as a liquid crystal alignment agent without being separated from the solvent.

[0036] The polyamic acid ester can be obtained by a synthesis method in which a polyamic acid is reacted with a hydroxyl group-containing compound, a halide, an epoxy group-containing compound, or the like. Alternatively, the polyamic acid ester can be obtained by a synthesis method in which a tetracarboxylic acid diester or a tetracarboxylic acid diester dichloride, which is a tetracarboxylic acid dianhydride derived from a tetracarboxylic acid dianhydride, is reacted with a diamine. The tetracarboxylic acid diester can be obtained, for example, by reacting a tetracarboxylic acid dianhydride with two equivalents of an alcohol to open the ring, and the tetracarboxylic acid diester dichloride can be obtained by reacting a tetracarboxylic acid diester with two equivalents of a chlorinating agent (e.g., thionyl chloride, etc.). The polyamic acid ester may have only an amic acid ester structure, or may be a partial ester in which an amic acid structure and an amic acid ester structure coexist.

[0037] The liquid crystal aligning agent of the present invention may contain only one or more of these polyamic acids or their derivatives, that is, polyamic acids, polyamic acid esters, and polyimides obtained by imidizing these.

[0038] The polyamic acid or its derivative of the present invention can be produced in the same manner as known polyamic acids or their derivatives used in the formation of polyimide films. The total amount of tetracarboxylic dianhydrides is preferably 0.9 to 1.1 moles per mole of the total amount of diamines.

[0039] The molecular weight of the polyamic acid or its derivative of the present invention is, in terms of polystyrene equivalent weight average molecular weight (Mw), preferably 5,000 to 500,000, more preferably 5,000 to 50,000. The molecular weight of the polyamic acid or its derivative can be determined by measurement using gel permeation chromatography (GPC).

[0040] The presence of the polyamic acid or its derivative of the present invention can be confirmed by analyzing the solid content obtained by precipitating the polyamic acid or its derivative with a large amount of poor solvent using IR (infrared spectroscopy) or NMR (nuclear magnetic resonance analysis).The monomer used can also be confirmed by analyzing an extract of the decomposition product of the polyamic acid or its derivative with an aqueous solution of a strong alkali such as KOH or NaOH using an organic solvent using GC (gas chromatography), HPLC (high performance liquid chromatography) or GC-MS (gas chromatography mass spectrometry).

[0041] <Other diamines> Diamines other than the compounds represented by formula (1) or (4) used as raw materials for the polymer of the present invention can be selected from known diamines without any limitation.

[0042] Examples of known diamines are shown as compounds represented by the following formulas (DI-1) to (DI-16). TIFF0007647448000019.tif126136 In the above formula (DI-1), G 20 is -CH2- or a group represented by formula (DI-1-a). 20 is -CH2-, at least one of the m -CH2- may be replaced with -NH- or -O-, and at least one hydrogen atom of the m -CH2- may be replaced with a hydroxyl group or a methyl group. m is an integer of 1 to 12. When m in DI-1 is 2 or more, multiple G 20 may be the same or different from each other, provided that G 20 When the formula is (DI-1-a), m is 1. TIFF0007647448000020.tif2747 In formula (DI-1-a), each v is independently an integer of 1 to 6.

[0043] In formula (DI-3), formula (DI-6) and formula (DI-7), G 21are each independently a single bond, -NH-, -NCH3-, -O-, -S-, -SS-, -SO2-, -CO-, -COO-, -CONCH3-, -CONH-, -C(CH3)2-, -C(CF3)2-, -(CH2) m -, -O-(CH2) m -O-, -N(CH3)-(CH2) k -N(CH3)-, -(O-C2H4) m -O-, -O-CH2-C(CF3)2-CH2-O-, -O-CO-(CH2) m -CO-O-, -CO-O-(CH2) m -O-CO-, -(CH2) m -NH-(CH2) m -, -CO-(CH2) k -NH-(CH2) k -, -(NH-(CH2) m ) k -NH-, -CO-C3H6-(NH-C3H6) n -CO- or -S-(CH2) m Each m is independently an integer of 1 to 12; each k is independently an integer of 1 to 5; and n is 1 or 2. In formula (DI-4), each s is independently an integer of 0 to 2.

[0044] In formula (DI-5), G 33 is a single bond, -NH-, -NCH3-, -O-, -S-, -SS-, -SO2-, -CO-, -COO-, -CONCH3-, -CONH-, -C(CH3)2-, -C(CF3)2-, -(CH2) m -, -O-(CH2) m -O-, -(O-C2H4) m -O-, -O-CH2-C(CF3)2-CH2-O-, -O-CO-(CH2) m -CO-O-, -CO-O-(CH2) m -O-CO-, -(CH2) m -NH-(CH2) m -, -CO-(CH2) k -NH-(CH2) k -, -(NH-(CH2) m )k -NH-, -CO-C3H6-(NH-C3H6) n -CO- or -S-(CH2) m -S-, -N(Boc)-(CH2) e -N(Boc)-, -NH-(CH2) e -N(Boc)-, -N(Boc)-(CH2) e -, -(CH2) m -N(Boc)-CONH-(CH2) m -, -(CH2) m -N(Boc)-(CH2) m -, a group represented by the following formula (DI-5-a) or the following formula (DI-5-b), wherein m is independently an integer of 1 to 12, k is independently an integer of 1 to 5, n is 1 or 2, and e is independently an integer of 2 to 10. Boc is a t-butoxycarbonyl group.

[0045] In formula (DI-6) and formula (DI-7), G 22 are each independently a single bond, -O-, -S-, -CO-, -C(CH3)2-, -C(CF3)2-, or an alkylene group having 1 to 10 carbon atoms.

[0046] At least one hydrogen atom of the cyclohexane ring and the benzene ring in the formulae (DI-2) to (DI-7) may be substituted with -F, -Cl, an alkyl group having 1 to 3 carbon atoms, -OCH3, -OH, -CF3, -CO2H, -CONH2, -NHC6H5, a phenyl group, or a benzyl group. In addition, in the formula (DI-4), at least one hydrogen atom of the benzene ring may be substituted with one selected from the group of groups represented by any of the following formulae (DI-4-a) to (DI-4-i). In the formula (DI-5), G 33 When is a single bond, at least one hydrogen atom of the benzene ring may be replaced by -NHBoc or -N(Boc)2.

[0047] A group that is not fixed to a carbon atom constituting a ring means that it can be bonded to any available carbon atom in the ring. And the bonding position of -NH2 to the cyclohexane ring or benzene ring is G 21 , G 22 or G 33 are possible binding positions excluding the binding position of TIFF0007647448000021.tif38140 TIFF0007647448000022.tif42150 In formula (DI-4-a) and formula (DI-4-b), R 20 are each independently a hydrogen atom or -CH3. In formulae (DI-4-f) and (DI-4-g), m is each independently an integer of 0 to 12, and Boc is a t-butoxycarbonyl group.

[0048] In formula (DI-5-a), each q is independently an integer of 0 to 6. 44 is a hydrogen atom, -OH, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0049] TIFF0007647448000024.tif84130 In formula (DI-11), r is 0 or 1. In formulas (DI-8) to (DI-11), -NH2 bonded to a ring can be bonded to any of the available carbons in the ring.

[0050] TIFF0007647448000025.tif127132 In formula (DI-12), R 21 and R 22 are each independently an alkyl group having 1 to 3 carbon atoms or a phenyl group, G 23 each independently represents an alkylene group having 1 to 6 carbon atoms, a phenylene group, or a phenylene group substituted with an alkyl group; and w is an integer of 1 to 10. In formula (DI-13), R 23each independently represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or -Cl; each p independently represents an integer of 0 to 3; and q represents an integer of 0 to 4. In formula (DI-14), ring B is a monocyclic heteroaromatic group, and R 24 is a hydrogen atom, -F, -Cl, an alkyl group, an alkoxy group, an alkenyl group, or an alkynyl group having 1 to 6 carbon atoms, and q is an integer of 0 to 4. When q is 2 or more, multiple R 24 may be the same or different. In formula (DI-15), ring C is a heterocyclic aromatic group or a heterocyclic aliphatic group. In formula (DI-16), G 24 is a single bond, an alkylene group having 2 to 6 carbon atoms, or a 1,4-phenylene group, and r is 0 or 1. A group that is not fixed to a carbon atom constituting a ring can be bonded to any available carbon atom in the ring. In formulae (DI-13) to (DI-16), -NH2 bonded to a ring can be bonded to any available carbon atom in the ring.

[0051] Examples of the diamine represented by formula (DI-1) are shown in the following formulas (DI-1-1) to (DI-1-9). TIFF0007647448000026.tif99150 In formula (DI-1-7) and formula (DI-1-8), k is independently an integer of 1 to 3. In formula (DI-1-9), v is independently an integer of 1 to 6.

[0052] Examples of diamines represented by formulae (DI-2) to (DI-3) are shown below as compounds represented by formulae (DI-2-1), (DI-2-2), and (DI-3-1) to (DI-3-3). TIFF0007647448000027.tif54150

[0053] Examples of the diamine represented by formula (DI-4) are shown in the following formulas (DI-4-1) to (DI-4-27). TIFF0007647448000028.tif67136 TIFF0007647448000029.tif65141 TIFF0007647448000030.tif46141 TIFF0007647448000031.tif48146 TIFF0007647448000032.tif3096 TIFF0007647448000033.tif39150 In formulas (DI-4-20) and (DI-4-21), each m is independently an integer of 1 to 12. TIFF0007647448000034.tif84153

[0054] Examples of the diamine represented by formula (DI-5) are shown below as compounds represented by formulae (DI-5-1) to (DI-5-50). TIFF0007647448000035.tif77150 In formula (DI-5-1), m is an integer of 1 to 12.

[0055] TIFF0007647448000036.tif66127 In formula (DI-5-12) and formula (DI-5-13), each m is independently an integer of 1 to 12.

[0056] TIFF0007647448000037.tif94132 In formula (DI-5-16), v is an integer of 1 to 6.

[0057] TIFF0007647448000038.tif94150

[0058] TIFF0007647448000039.tif130143 In Formulas (DI-5-35) to (DI-5-37) and (DI-5-39), m is each independently an integer of 1 to 12; in Formulas (DI-5-38) and (DI-5-39), k is each independently an integer of 1 to 5; and in Formula (DI-5-40), n is an integer of 1 or 2.

[0059] TIFF0007647448000040.tif54138 In formulas (DI-5-42) to (DI-5-44), e is independently an integer of 2 to 10, and in formula (DI-5-45), R 43 R in Formula (DI-5-42) to Formula (DI-5-44) and Formula (DI-5-45) are each independently a hydrogen atom, -NHBoc, or -N(Boc)2. 43 In the formula, Boc is a t-butoxycarbonyl group.

[0060] TIFF0007647448000041.tif44112 TIFF0007647448000042.tif2672 TIFF0007647448000043.tif35150

[0061] Examples of the diamine represented by formula (DI-6) are shown below as compounds represented by formulas (DI-6-1) to (DI-6-7). TIFF0007647448000044.tif86150

[0062] Examples of the diamine represented by formula (DI-7) are shown in the following formulas (DI-7-1) to (DI-7-11). TIFF0007647448000045.tif109118 In formula (DI-7-3) and formula (DI-7-4), each m is independently an integer of 1 to 12, and each n is independently 1 or 2.

[0063] TIFF0007647448000046.tif11184 TIFF0007647448000047.tif3979

[0064] Examples of the diamine represented by formula (DI-8) are shown below as the compounds represented by formulas (DI-8-1) to (DI-8-4). TIFF0007647448000048.tif31140

[0065] Examples of the diamine represented by formula (DI-9) are shown in the following formulas (DI-9-1) to (DI-9-3). TIFF0007647448000049.tif34143

[0066] Examples of the diamine represented by formula (DI-10) are shown below as compounds represented by formulas (DI-10-1) and (DI-10-2). TIFF0007647448000050.tif3189

[0067] Examples of the diamine represented by formula (DI-11) are shown below as compounds represented by formulas (DI-11-1) to (DI-11-3). TIFF0007647448000051.tif23140

[0068] An example of the diamine represented by formula (DI-12) is shown below as a compound represented by formula (DI-12-1). TIFF0007647448000052.tif2866

[0069] Examples of diamines represented by formula (DI-13) are shown below as compounds represented by formulas (DI-13-1) to (DI-13-13). TIFF0007647448000053.tif23130 TIFF0007647448000054.tif66132 TIFF0007647448000055.tif66130

[0070] Examples of the diamine represented by formula (DI-14) are shown below as compounds represented by formulas (DI-14-1) to (DI-14-9). TIFF0007647448000056.tif74117

[0071] Examples of the diamine represented by formula (DI-15) are shown below as the compounds represented by formulas (DI-15-1) to (DI-5-12). TIFF0007647448000057.tif64150 TIFF0007647448000058.tif61150

[0072] An example of the diamine represented by formula (DI-16) is shown in the following formula (DI-16-1). TIFF0007647448000059.tif2659

[0073] Next, the dihydrazide used as the raw material for the polymer of the present invention will be described. Known dihydrazides include compounds represented by any of the following formulae (DIH-1) to (DIH-3). TIFF0007647448000060.tif56102 In formula (DIH-1), G 25 is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO2-, -C(CH3)2-, or -C(CF3)2-. In formula (DIH-2), ring D is a cyclohexane ring, a benzene ring or a naphthalene ring, and at least one hydrogen atom of this group may be substituted with a methyl group, an ethyl group, or a phenyl group. In formula (DIH-3), each ring E is independently a cyclohexane ring or a benzene ring, and at least one hydrogen atom of this group may be substituted with a methyl group, an ethyl group, or a phenyl group. Y is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO2-, -C(CH3)2-, or -C(CF3)2-. In formula (DIH-2) and formula (DIH-3), -CONHNH2 bonded to a ring can be bonded to any available carbon in the ring.

[0074] Examples of the compounds represented by any one of formulas (DIH-1) to (DIH-3) are shown below as compounds represented by formulas (DIH-1-1), (DIH-1-2), (DIH-2-1) to (DIH-2-3), and (DIH-3-1) to (DIH-3-6). TIFF0007647448000061.tif2689 In formula (DIH-1-2), m is an integer of 1 to 12.

[0075] TIFF0007647448000062.tif31148 TIFF0007647448000063.tif84137

[0076] The above diamines are preferably used selectively for the purpose of improving characteristics such as VHR, afterimage characteristics, etc. Materials suitable for improving the characteristics of the liquid crystal alignment film are described below.

[0077] When it is important to improve the liquid crystal alignment, it is preferable to use a compound represented by formula (DI-1-3), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula (DI-5-13), formula (DI-5-29), formula (DI-6-7), formula (DI-7-3), or formula (DI-11-2). In formula (DI-5-1), m is preferably 2 to 8, and more preferably m is 4 to 8. In formula (DI-5-12), m is preferably 2 to 6, and more preferably m is 5. In formula (DI-5-13), m is preferably 1 or 2, and more preferably m is 1.

[0078] When emphasis is placed on improving the transmittance, it is preferable to use a diamine represented by formula (DI-1-3), formula (DI-2-1), formula (DI-5-1), formula (DI-5-5), formula (DI-5-24), or formula (DI-7-3), and more preferably a compound represented by formula (DI-2-1). In formula (DI-5-1), m is preferably 2 to 8, and more preferably m is 8. In formula (DI-7-3), m is preferably 2 or 3, n is preferably 1 or 2, and more preferably m is 3, n is preferably 1.

[0079] When it is important to improve the VHR of the liquid crystal display element, it is preferable to use a compound represented by formula (DI-2-1), formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-4-22), formula (DI-5-1), formula (DI-5-28), formula (DI-5-30), or formula (DI-13-1), and more preferable is a diamine represented by formula (DI-2-1), formula (DI-5-1), or formula (DI-13-1). In formula (DI-5-1), m=1 is preferable. In formula (DI-5-30), k=2 is preferable.

[0080] In the case where it is important to improve the relaxation speed of the accumulated charge of the liquid crystal display element, it is preferable to use a compound represented by formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-5-1), formula (DI-5-12), formula (DI-5-13), formula (DI-5-28), formula (DI-4-20), formula (DI-4-21), or formula (DI-16-1), and more preferable is a compound represented by formula (DI-4-1), formula (DI-5-1), or formula (DI-5-13). In formula (DI-5-1), m is preferably 2 to 8, and more preferably m is 4 to 8. In formula (DI-5-12), m is preferably 2 to 6, and more preferably m is 5. In formula (DI-5-13), m is preferably 1 or 2, and more preferably m is 1.

[0081] In addition to the above diamines, diamines having large side chain groups suitable for increasing the pretilt angle can also be used. The compound of the present invention can be suitably used as a liquid crystal alignment agent for use in a horizontal electric field type liquid crystal display element (for example, an IPS mode or FFS mode liquid crystal display element), but it is also possible to increase the pretilt angle by using a diamine having a large side chain group in combination. As diamines having side chain groups suitable for increasing the pretilt angle, reference can be made to the description of diamines suitable for increasing the pretilt angle described in Patent Document 4.

[0082] In the raw material composition used as the raw material of the polymer of the present invention, a part of the diamines may be replaced with at least one selected from the group consisting of monoamines and monohydrazides. The ratio of the at least one selected from the group consisting of monoamines and monohydrazides to the diamines is preferably in the range of 40 mol% or less. Such a replacement can cause the termination of the polymerization reaction when producing polyamic acid, and can suppress the further progress of the polymerization reaction. For this reason, such a replacement can easily control the molecular weight of the resulting polymer (polyamic acid or its derivative), and can improve the coating properties of the liquid crystal alignment agent, for example, without impairing the effects of the present invention. The diamines that may be replaced with monoamines or monohydrazides may be one type or two or more types, as long as the effects of the present invention are not impaired. Examples of the monoamine include aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine, para-aminophenyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

[0083] <Other tetracarboxylic dianhydrides> The tetracarboxylic dianhydrides other than those of formula (2) or (3) used as the raw material for the polymer of the present invention can be selected from known tetracarboxylic dianhydrides without any limitation.

[0084] Examples of tetracarboxylic dianhydrides are shown below. These tetracarboxylic dianhydrides may be converted into tetracarboxylic diesters or tetracarboxylic diester dichlorides and used as raw materials for polymers.

[0085] Such tetracarboxylic dianhydrides may belong to either an aromatic group (including a heteroaromatic ring system) in which a dicarboxylic anhydride is directly bonded to an aromatic ring, or an aliphatic group (including a heterocyclic ring system) in which a dicarboxylic anhydride is not directly bonded to an aromatic ring.

[0086] Examples of such tetracarboxylic dianhydrides include the compounds represented by the following formulae (AN-1) to (AN-9), (AN-11), (AN-12), (AN-15), (AN-10-1), (AN-10-2), and (AN-16-1) to (AN-16-17).

[0087] [Tetracarboxylic acid dianhydride represented by formula (AN-1)] TIFF0007647448000064.tif3595 In formula (AN-1), G 11 X is a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group, or a 1,4-cyclohexylene group. 11 Each is independently a single bond or -CH2-. 12 each independently represents one of the following trivalent groups: TIFF0007647448000065.tif1851 G 12 When is >CH-, the hydrogen atom of >CH- may be substituted with a methyl group. 12 When is >N-, G 11 is not a single bond or -CH2-, and X 11 R cannot be a single bond. 11 are each independently a hydrogen atom or a methyl group.

[0088] Examples of the tetracarboxylic dianhydride represented by formula (AN-1) include the compounds represented by the following formulae (AN-1-1) to (AN-1-15). TIFF0007647448000066.tif140140 In formulas (AN-1-2) and (AN-1-14), each m is independently an integer of 1 to 12.

[0089] [Tetracarboxylic acid dianhydride represented by formula (AN-2)] TIFF0007647448000067.tif3631 In formula (AN-2), R 61 are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group.

[0090] Examples of the tetracarboxylic dianhydride represented by formula (AN-2) include the compounds represented by the following formulae (AN-2-1) to (AN-2-3). TIFF0007647448000068.tif38127

[0091] [Tetracarboxylic acid dianhydride represented by formula (AN-3)] TIFF0007647448000069.tif2874 In formula (AN-3), ring A 11 is a cyclohexane ring or a benzene ring.

[0092] Examples of the tetracarboxylic dianhydride represented by formula (AN-3) include compounds represented by the following formulae (AN-3-1) and (AN-3-2). TIFF0007647448000070.tif2877

[0093] [Tetracarboxylic acid dianhydride represented by formula (AN-4)] TIFF0007647448000071.tif2882 In formula (AN-4), G 13 is a single bond, -(CH2) m-, -O-, -S-, -C(CH3)2-, -SO2-, -CO-, -C(CF3)2-, or a divalent group represented by the following formula (G13-1), where m is an integer of 1 to 12. 11 are each independently a cyclohexane ring or a benzene ring. 13 is ring A 11 It can bond to any of the available carbons. TIFF0007647448000072.tif2497 In formula (G13-1), G 13a and G 13b are each independently a single bond, or a divalent group represented by -O-, -CONH-, or -NHCO-. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.

[0094] Examples of the tetracarboxylic dianhydride represented by formula (AN-4) include the compounds represented by the following formulae (AN-4-1) to (AN-4-31). TIFF0007647448000073.tif111143 TIFF0007647448000074.tif143138 In formula (AN-4-17), m is an integer from 1 to 12.

[0095] TIFF0007647448000075.tif61125 TIFF0007647448000076.tif61150

[0096] [Tetracarboxylic acid dianhydride represented by formula (AN-5)] TIFF0007647448000077.tif4174 In formula (AN-5), R 11 are each independently a hydrogen atom or a methyl group. 11 Among them, R in the benzene ring 11 is attached to any of the substitutable positions of the benzene ring.

[0097] Examples of the tetracarboxylic dianhydride represented by formula (AN-5) include the compounds represented by the following formulae (AN-5-1) to (AN-5-3). TIFF0007647448000078.tif50136

[0098] [Tetracarboxylic acid dianhydride represented by formula (AN-6)] TIFF0007647448000079.tif30102 In formula (AN-6), X 11 Each independently is a single bond or -CH2-. 12 is -CH2-, -CH2CH2- or -CH=CH-. n is 1 or 2. When n is 2, two X 12 may be the same or different from each other.

[0099] Examples of the tetracarboxylic dianhydride represented by formula (AN-6) include the compounds represented by the following formulae (AN-6-1) to (AN-6-12). TIFF0007647448000080.tif115132

[0100] [Tetracarboxylic dianhydride represented by formula (AN-7)] In the TIFF0007647448000081.tif3584 formula (AN-7), X 11 is a single bond or -CH2-.

[0101] Examples of the tetracarboxylic dianhydride represented by formula (AN-7) include the compounds represented by the following formulae (AN-7-1) and (AN-7-2). TIFF0007647448000082.tif3987

[0102] [Tetracarboxylic dianhydride represented by formula (AN-8)] TIFF0007647448000083.tif4687 In formula (AN-8), X 11 is a single bond or -CH2-. 12 is a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. 12 is a cyclohexane ring or a cyclohexene ring.

[0103] Examples of the tetracarboxylic dianhydride represented by formula (AN-8) include the compounds represented by the following formulae (AN-8-1) and (AN-8-2). TIFF0007647448000084.tif5387

[0104] [Tetracarboxylic acid dianhydride represented by formula (AN-9)] TIFF0007647448000085.tif3788 In formula (AN-9), each r is independently 0 or 1.

[0105] Examples of the tetracarboxylic dianhydride represented by formula (AN-9) include the compounds represented by the following formulae (AN-9-1) to (AN-9-3). TIFF0007647448000086.tif36150

[0106] [Tetracarboxylic acid dianhydrides represented by formula (AN-10-1) and formula (AN-10-2)] TIFF0007647448000087.tif3986

[0107] [Tetracarboxylic dianhydride represented by formula (AN-11)] TIFF0007647448000088.tif3285 In formula (AN-11), ring A11 are each independently a cyclohexane ring or a benzene ring.

[0108] Examples of the tetracarboxylic dianhydride represented by formula (AN-11) include the compounds represented by the following formulae (AN-11-1) to (AN-11-3). TIFF0007647448000089.tif31147

[0109] [Tetracarboxylic dianhydride represented by formula (AN-12)] TIFF0007647448000090.tif4091 In formula (AN-12), ring A 11 are each independently a cyclohexane ring or a benzene ring.

[0110] Examples of the tetracarboxylic dianhydride represented by formula (AN-12) include the compounds represented by the following formulae (AN-12-1) to (AN-12-3). TIFF0007647448000091.tif39150

[0111] [Tetracarboxylic dianhydride represented by formula (AN-15)] TIFF0007647448000092.tif3098 In formula (AN-15), w is an integer of 1 to 10.

[0112] Examples of the tetracarboxylic dianhydride represented by formula (AN-15) include the compounds represented by the following formulae (AN-15-1) to (AN-15-3). TIFF0007647448000093.tif28146

[0113] Other tetracarboxylic dianhydrides include the compounds represented by the following formulae (AN-16-1) to (AN-16-17). TIFF0007647448000094.tif188138

[0114] Among the above tetracarboxylic dianhydrides, preferred materials for improving the properties of the liquid crystal alignment film described below will be described. When emphasis is placed on further improving the liquid crystal alignment property, the compounds represented by formula (AN-1-2), formula (AN-4-17), formula (AN-4-21), formula (AN-4-29), or formula (AN-16-17) are more preferred, and in formula (AN-1-2), m is preferably 4 to 8, more preferably 4, 6, or 8. In formula (AN-4-17), m is preferably 4 to 8, more preferably 4 or 8.

[0115] When emphasis is placed on improving the transmittance of a liquid crystal display element, the compounds represented by formula (AN-1-1), (AN-1-2), (AN-2-1), (AN-3-1), (AN-4-17), (AN-4-30), (AN-5-1), (AN-7-2), (AN-10-1), (AN-16-3) or (AN-16-4) are preferred, and in formula (AN-1-2), m is preferably 4 to 8, and in formula (AN-4-17), m is preferably 4 to 8.

[0116] When emphasis is placed on improving the VHR of a liquid crystal display element, the compounds represented by formula (AN-1-1), formula (AN-1-2), formula (AN-3-1), formula (AN-4-17), formula (AN-4-30), formula (AN-7-2), formula (AN-10-1), formula (AN-16-3), formula (AN-16-4), or formula (AN-2-1) are preferred, and in formula (AN-1-2), m is preferably 4 to 8, and in formula (AN-4-17), m is preferably 4 to 8.

[0117] When emphasis is placed on further improving the relaxation speed of accumulated charges in a liquid crystal display element, the compounds represented by formula (AN-1-13), formula (AN-3-2), formula (AN-4-21), formula (AN-4-29), or formula (AN-11-3) are preferred.

[0118] In the raw material composition used as the raw material for the polymer of the present invention, the compound represented by formula (1) is preferably 50 to 100 mol %, more preferably 80 to 100 mol %, based on the total amount of diamines used. When the compound represented by formula (4) is used in combination, the compound represented by formula (4) is preferably 5 to 50 mol %, more preferably 5 to 20 mol %, based on the total amount of diamines used. The tetracarboxylic dianhydrides represented by formula (2) or formula (3) are preferably 30 to 100 mol %, more preferably 50 to 100 mol %, based on the total amount of tetracarboxylic dianhydrides used.

[0119] The polymer of the present invention may further contain a monoisocyanate compound as its raw material composition. By including a monoisocyanate compound in the raw material composition, the terminal of the obtained polyamic acid or its derivative is modified, and the molecular weight is adjusted. By using this terminal-modified polyamic acid or its derivative, for example, the coating properties of the liquid crystal alignment agent can be improved without impairing the effect of the present invention. From the above viewpoint, it is preferable that the content of the monoisocyanate compound in the raw material composition is 1 to 10 mol% with respect to the total amount of diamines and tetracarboxylic dianhydrides in the raw material composition. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

[0120] <Liquid crystal alignment agent> The polymer component in the liquid crystal alignment agent of the present invention will be described in detail below. The polymer component in the liquid crystal alignment agent of the present invention may contain one type of polymer of the present invention, may contain two or more types of polymer of the present invention, or may be a mixture of the polymer of the present invention and a polymer other than the present invention. In this specification, a liquid crystal alignment agent composed of one type of polymer may be referred to as a "single-layer type liquid crystal alignment agent". A liquid crystal alignment agent that mixes two or more types of polymers may be referred to as a "blend type liquid crystal alignment agent". A blend type liquid crystal alignment agent is used particularly when VHR reliability and other electrical properties are important.

[0121] The polymer used in the blend type liquid crystal alignment agent may be composed of a polymer using a compound of formula (1), formula (2) or formula (3) as a raw material and a polymer not using a compound of formula (1), formula (2) or formula (3) as a raw material, or may be composed of two or more polymers using a compound of formula (1), formula (2) or formula (3) as a raw material. As for the polymer not using a compound of formula (1), formula (2) or formula (3) as a raw material, the above description of the polymer of the present invention can be referred to except that it does not contain a compound of formula (1), formula (2) or formula (3) as a raw material.

[0122] When using a two-component polymer, for example, one embodiment is to select a polymer having excellent performance in liquid crystal alignment ability as one component, and a polymer having excellent performance in improving the electrical characteristics of a liquid crystal display element as the other component, which is suitable for obtaining an alignment agent with a good balance between liquid crystal alignment ability and electrical characteristics.

[0123] In this case, by controlling the structure and molecular weight of each polymer, the liquid crystal alignment agent in which these polymers are dissolved in a solvent is applied to a substrate as described below, and in the process of forming a thin film by pre-drying, the polymer having excellent performance in liquid crystal alignment ability can be segregated in the upper layer of the thin film, and the polymer having excellent performance in improving the electrical properties of the liquid crystal display element can be segregated in the lower layer of the thin film. For this, the phenomenon in which a polymer with a small surface energy is in the upper layer and a polymer with a large surface energy is in the lower layer in the mixed polymers can be applied. Such phase separation can be confirmed by checking that the surface energy of the formed liquid crystal alignment film is the same as or close to the surface energy of a film formed by a liquid crystal alignment agent containing only the polymer intended to be segregated in the upper layer.

[0124] One method for realizing a phase-separated structure with two upper and lower layers is to reduce the molecular weight of the polymer to be segregated into the upper layer.

[0125] In the case of a liquid crystal alignment agent consisting of a mixture of polymers, a phase-separated structure of upper and lower layers can be expressed by using polyimide as the polymer to be segregated in the upper layer.

[0126] The diamines represented by formula (1) may be used as a raw material composition for a polymer that segregates in the upper layer of the thin film, or may be used as a raw material composition for a polymer that segregates in the lower layer of the thin film, or may be used as raw material compositions for both polymers. However, it is more preferable to use the diamines as a raw material composition for a polymer that segregates in the upper layer of the thin film.

[0127] The tetracarboxylic dianhydrides represented by the formula (2) or the formula (3) may be used as a raw material composition for a polymer that segregates in the upper layer of the thin film, or may be used as a raw material composition for a polymer that segregates in the lower layer of the thin film, or may be used as raw material compositions for both polymers.

[0128] The diamines represented by formula (4) may be used as a raw material composition for a polymer that segregates in the upper layer of the thin film, or may be used as a raw material composition for a polymer that segregates in the lower layer of the thin film, or may be used as raw material compositions for both polymers.

[0129] The tetracarboxylic dianhydrides used for synthesizing the polymer that segregates in the upper layer of the thin film can be selected from the known tetracarboxylic dianhydrides exemplified above or their derivative compounds without any limitation.

[0130] The tetracarboxylic dianhydrides other than those represented by formula (1) or formula (2) used to synthesize the polymer segregated in the upper layer of the thin film are preferably compounds represented by formula (AN-1-1), formula (AN-1-2), formula (AN-2-1), formula (AN-3-1), formula (AN-4-5), formula (AN-4-17), or formula (AN-4-21), or derivative compounds thereof, more preferably formula (AN-4-17) or formula (AN-4-21). In formula (AN-4-17), m is preferably 4 to 8.

[0131] The diamines used to synthesize the polymer that segregates in the upper layer of the thin film can be selected from the known diamines exemplified above without any limitation.

[0132] As the diamines used to synthesize the polymer segregated in the upper layer of the thin film, it is preferable to use a compound represented by formula (DI-4-1), formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), formula (DI-7-3), formula (DI-13-1), (V-2-1), (V-2-13), (V-2-14), (V-2-15), or (V-2-16). Among them, it is more preferable to use a compound represented by formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), formula (DI-13-1), (V-2-1), (V-2-13), or (V-2-15). In formula (DI-5-1), m=4 to 8 is preferable. In formula (DI-7-3), m=3 and n=1 are preferable.

[0133] The tetracarboxylic dianhydrides used for synthesizing the polymer that segregates in the lower layer of the thin film can be selected from the known tetracarboxylic dianhydrides exemplified above or their derivative compounds without any limitation.

[0134] As the tetracarboxylic dianhydrides other than those represented by formula (1) or (2) used for synthesizing the polymer segregating in the lower layer of the thin film, the compounds represented by formula (AN-1-1), (AN-1-13), (AN-2-1), (AN-3-2) or (AN-4-21) or their derivative compounds are preferred, and the compounds represented by formula (AN-1-1), (AN-2-1) or (AN-3-2) are more preferred.

[0135] Tetracarboxylic dianhydrides preferably used for synthesizing a polymer that segregates in the lower layer of a thin film preferably contain aromatic tetracarboxylic dianhydrides in an amount of 10 mol % or more, more preferably 30 mol % or more, based on the total amount of tetracarboxylic dianhydrides.

[0136] The diamines used to synthesize the polymer that segregates in the lower layer of the thin film can be selected from the known diamines exemplified above without any limitation.

[0137] As diamines used to synthesize a polymer that segregates in the lower layer of a thin film, compounds represented by formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-18), formula (DI-4-19), formula (DI-5-1), formula (DI-5-9), formula (DI-5-28), formula (DI-5-30), formula (DI-13-1), or formula (DIH-1-2) are preferred. In formula (DI-5-1), compounds in which m=1 or 2 are preferred, and in formula (DI-5-30), compounds in which k=2 are preferred. Among these, compounds represented by formula (DI-4-1), formula (DI-4-18), formula (DI-4-19), formula (DI-5-9), formula (DI-13-1), or formula (DIH-1-2) are more preferred.

[0138] Diamines preferably used for synthesizing a polymer that segregates in the lower layer of a thin film preferably contain at least one selected from the group consisting of aromatic diamines and aromatic dihydrazides in an amount of 30 mol % or more, and more preferably 50 mol % or more, based on the total amount of diamines.

[0139] The ratio of the polymer segregated in the upper layer of the thin film to the total amount of the polymer segregated in the upper layer of the thin film and the polymer segregated in the lower layer of the thin film is preferably 5% by weight to 50% by weight, more preferably 10% by weight to 40% by weight.

[0140] The polyamic acid or derivative thereof of the present invention may be a block polymer including a first polymer chain and a second polymer chain having a structure different from that of the first polymer chain. The block polymer may further include another polymer chain having a structure different from that of the first polymer chain and the second polymer chain. For example, a block polymer of polyamic acid is prepared by mixing a solution of a specific polyamic acid (PAA1) represented by the following formula (PAA) and a solution of polyamic acid (PAA1) and X1 and X 2 The block polymer of polyamic acid (PAA1) can be formed by mixing and heating solutions of polyamic acid (PAA2) with different combinations of (PAA1) and (PAA2). n1 and (PAA2) n2 (PAA1) n1 and (PAA2) n2 In the block polymer, n1 and n2 are each independently an integer of 1 or more, and preferably each independently an integer of 2 or more. In the block polymer, the compound represented by formula (1) and the tetracarboxylic dianhydride represented by formula (2) or formula (3) may be used in one or more of the polymer chains in the raw material composition, or may be used in all of the polymer chains. TIFF0007647448000095.tif3646

[0141] In the block polymer, the polymer chain using the compound represented by formula (1) and the tetracarboxylic dianhydride represented by formula (2) or formula (3) as the raw material composition preferably accounts for 5 to 50% by weight, more preferably 10 to 40% by weight, of the entire block polymer.

[0142] Here, the polyamic acid block polymer may be synthesized by mixing two or more kinds of polyamic acids produced individually and then heating them, or by synthesizing two or more kinds of polyamic acids in the same reaction vessel and then heating them, such as by synthesizing the first kind of polyamic acid and then adding the raw material of the second kind of polyamic acid to the same reaction vessel.

[0143] In addition, the liquid crystal aligning agent of the present invention may further contain a solvent from the viewpoint of adjusting the coating property of the liquid crystal aligning agent and the concentration of the polyamic acid or its derivative. The solvent can be applied without any particular limitation as long as it has the ability to dissolve the polymer component. The solvent includes a wide range of solvents that are commonly used in the manufacturing process and applications of polymer components such as polyamic acid and soluble polyimide, and can be appropriately selected depending on the purpose of use. The solvent may be one type or a mixed solvent of two or more types.

[0144] Examples of the solvent include a solvent compatible with the polymer component and other solvents for the purpose of improving the coatability.

[0145] Examples of the aprotic polar organic solvent that is a solvent compatible with the polymer component include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N,N-dimethylacetamide, dimethylsulfoxide, N,N-dimethylformamide, N,N-diethylformamide, diethylacetamide, N,N-dimethylisobutylamide, γ-butyrolactone, and γ-valerolactone. Among these, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, and γ-valerolactone are preferred.

[0146] Examples of other solvents for improving coating properties include ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether and ethylene glycol monotertiary butyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, and diethylene glycol dialkyl ethers such as diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and diethylene glycol butyl methyl ether. In addition, propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether and 1-butoxy-2-propanol, dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, triethylene glycol monoalkyl ethers, butyl cellosolve acetate, phenyl acetate, and ester compounds such as these acetates. In addition, dialkyl malonates such as diethyl malonate, alkyl lactates, diisobutyl ketone, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol, diisobutyl carbinol, tetralin, and isophorone.

[0147] Of these, diisobutyl ketone, 4-methyl-2-pentanol, diisobutyl carbinol, ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monoethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, 1-butoxy-2-propanol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, or butyl cellosolve acetate is preferred.

[0148] The polymer concentration in the liquid crystal aligning agent of the present invention is not particularly limited, and an optimal value may be selected according to the various coating methods described below. In general, in order to suppress unevenness and pinholes during coating, the polymer concentration is preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight, based on the weight of the varnish.

[0149] The preferred range of the viscosity of the liquid crystal alignment agent of the present invention varies depending on the application method, the concentration of the polymer component, the type of the polymer component used, and the type and ratio of the solvent. For example, in the case of application by a printer, the viscosity is 5 to 100 mPa·s (more preferably 10 to 80 mPa·s). If the viscosity is 5 mPa·s or more, a sufficient film thickness is easily obtained, and if the viscosity is 100 mPa·s or less, printing unevenness is easily suppressed. In the case of application by spin coating, the viscosity is suitable to be 5 to 200 mPa·s (more preferably 10 to 100 mPa·s). In the case of application by an inkjet coater, the viscosity is suitable to be 5 to 50 mPa·s (more preferably 5 to 20 mPa·s). The viscosity of the liquid crystal alignment agent is measured by a rotational viscosity measurement method, for example, using a rotational viscometer (TVE-20L type manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25°C).

[0150] The liquid crystal alignment agent of the present invention may further contain various additives. Various additives can be selected and used according to the respective purposes in order to improve various properties of the alignment film. Examples are shown below.

[0151] <Alkenyl-substituted nadimide compounds> For example, the liquid crystal aligning agent of the present invention may further contain an alkenyl-substituted nadiimide compound for the purpose of stabilizing the electrical properties of the liquid crystal display element for a long period of time. The alkenyl-substituted nadiimide compound may be used alone or in combination of two or more kinds. For the above purpose, the content of the alkenyl-substituted nadiimide compound is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, and even more preferably 1 to 20% by weight, based on the polymer component. The alkenyl-substituted nadiimide compound is preferably a compound that can be dissolved in a solvent that dissolves the polymer component used in the present invention. Preferred alkenyl-substituted nadiimide compounds include the alkenyl-substituted nadiimide compounds disclosed in JP-A-2008-096979, JP-A-2009-109987, and JP-A-2013-242526. Particularly preferred alkenyl-substituted nadimide compounds include bis{4-(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)phenyl}methane, N,N'-m-xylylene-bis(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide), or N,N'-hexamethylene-bis(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide).

[0152] <Compounds having radically polymerizable unsaturated double bonds> For example, the liquid crystal alignment agent of the present invention may further contain a compound having a radical polymerizable unsaturated double bond for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. The compound having a radical polymerizable unsaturated double bond may be one type of compound or two or more types of compounds. The compound having a radical polymerizable unsaturated double bond does not include an alkenyl-substituted nadiimide compound. Preferred compounds having a radical polymerizable unsaturated double bond include N,N'-methylenebisacrylamide, N,N'-dihydroxyethylene-bisacrylamide, ethylenebisacrylate, 4,4'-methylenebis(N,N-dihydroxyethyleneacrylateaniline), triallyl cyanurate, and other compounds having a radical polymerizable unsaturated double bond disclosed in JP 2009-109987 A, JP 2013-242526 A, WO 2014 / 119682, and WO 2015 / 152014. For the above-mentioned purposes, the content of the compound having a radically polymerizable unsaturated double bond is preferably 1 to 50% by weight, and more preferably 1 to 30% by weight, based on the polymer component.

[0153] <Oxazine compounds> For example, the liquid crystal aligning agent of the present invention may further contain an oxazine compound for the purpose of stabilizing the electrical properties of a liquid crystal display element for a long period of time. The oxazine compound may be one type of compound or two or more types of compounds. For the above purpose, the content of the oxazine compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and even more preferably 1 to 20% by weight, based on the polymer component.

[0154] The oxazine compound is preferably soluble in the solvent that dissolves the polymer component, and has ring-opening polymerizability.Preferred oxazine compounds include the oxazine compounds represented by formula (OX-3-1), formula (OX-3-9), and formula (OX-3-10), and also the oxazine compounds disclosed in JP-A-2007-286597 and JP-A-2013-242526. TIFF0007647448000096.tif72147

[0155] <Oxazoline compounds> For example, the liquid crystal aligning agent of the present invention may further contain an oxazoline compound for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time. The oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one type of compound or two or more types of compounds. For the above purpose, the content of the oxazoline compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and even more preferably 1 to 20% by weight, based on the polymer component. Preferred oxazoline compounds include the oxazoline compounds disclosed in JP-A-2010-054872 and JP-A-2013-242526. More preferably, 1,3-bis(4,5-dihydro-2-oxazolyl)benzene is used.

[0156] <Epoxy compounds> For example, the liquid crystal aligning agent of the present invention may further contain an epoxy compound for the purpose of stabilizing the electrical properties of a liquid crystal display element for a long period of time, improving the hardness of the film, or improving the adhesion to a sealant. The epoxy compound may be one type of compound or two or more types of compounds. For the above purposes, the content of the epoxy compound is preferably 0.1 to 50% by weight, more preferably 1 to 20% by weight, and even more preferably 1 to 10% by weight, based on the polymer component.

[0157] As the epoxy compound, various compounds having one or more epoxy rings in the molecule can be used. For the purpose of improving the hardness of the film or the purpose of improving the adhesion with the sealant, a compound having two or more epoxy rings in the molecule is preferred, and a compound having three or four epoxy rings is more preferred.

[0158] Examples of the epoxy compound include the epoxy compounds disclosed in JP-A-2009-175715, JP-A-2013-242526, JP-A-2016-170409, and WO 2017 / 217413. Preferred epoxy compounds include N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3,3',4,4'-diepoxy)bicyclohexyl, 1,4-butanediol glycidyl ether, tris(2,3-epoxypropyl)isocyanurate, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, or N,N,N',N'-tetraglycidyl-m-xylylenediamine. In addition to the above, an oligomer or polymer having an epoxy ring can be added. As the oligomer or polymer having an epoxy ring, the oligomer or polymer disclosed in JP-A-2013-242526 can be used.

[0159] <Silane compounds> For example, the liquid crystal aligning agent of the present invention may further contain a silane compound for the purpose of improving adhesion to a substrate and a sealant. For the above purpose, the content of the silane compound is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and further preferably 0.5 to 10% by weight, based on the polymer component.

[0160] As the silane compound, silane coupling agents disclosed in JP 2013-242526 A, JP 2015-212807 A, JP 2018-173545 A, and International Publication No. 2018 / 181566 can be used. Preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, paraaminophenyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-isocyanatepropyltriethoxysilane, and 3-ureidopropyltriethoxysilane.

[0161] In addition to the additives described above, a compound having a cyclocarbonate group, a hydroxyalkylamide moiety, or a hydroxyl group can be added for the purpose of increasing the strength of the alignment film or stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. Specific compounds include those disclosed in JP 2016-118753 A and WO 2017 / 110976 A. Preferred compounds include those represented by the following formulae (HD-1) to (HD-4). These compounds are preferably present in an amount of 0.5 to 50% by weight, more preferably 1 to 30% by weight, and even more preferably 1 to 10% by weight, based on the polymer component. TIFF0007647448000097.tif88126

[0162] In addition, when improved antistatic properties are required, antistatic agents can be used, and when imidization is to proceed at low temperatures, imidization catalysts can be used, such as those disclosed in JP-A-2013-242526.

[0163] <Liquid crystal alignment film> Next, the liquid crystal alignment film of the present invention will be described. The liquid crystal alignment film of the present invention is formed by using the liquid crystal alignment agent of the present invention. When the liquid crystal alignment agent of the present invention is used to form a liquid crystal alignment film, a polyimide-based liquid crystal alignment film can be formed by heating and baking the liquid crystal alignment film. The liquid crystal alignment agent of the present invention can be applied to a rubbing alignment film using a rubbing method as an alignment treatment method, and also to a photo-alignment film using a photo-alignment method as an alignment treatment method if a compound having a photoreactive structure is used in combination as a raw material.

[0164] Hereinafter, a method for forming a liquid crystal alignment film using the photo-alignment liquid crystal aligning agent of the present invention will be described.

[0165] The liquid crystal alignment film of the present invention can be obtained by a normal method of preparing a liquid crystal alignment film from a liquid crystal alignment agent for photo-alignment. The liquid crystal alignment film of the present invention can be obtained, for example, by going through a process of forming a coating film of the liquid crystal alignment agent for photo-alignment of the present invention, a process of heating and drying the coating film to form a film of the liquid crystal alignment agent, a process of irradiating the film of the liquid crystal alignment agent with light to impart anisotropy, and a process of heating and baking the film of the liquid crystal alignment agent to which anisotropy has been imparted. For the liquid crystal alignment film of the present invention, it is preferable to irradiate light after the coating process and the heating and drying process to impart anisotropy, and then go through a heating and baking process.

[0166] The coating film can be formed by applying the liquid crystal aligning agent of the present invention to a substrate of a liquid crystal display element in the same manner as in the preparation of a normal liquid crystal alignment film. The substrate may be made of glass, silicon nitride, acrylic, polycarbonate, polyimide, or the like, which may be provided with a transparent electrode, a color filter, or the like.

[0167] Generally known methods for applying a liquid crystal alignment agent to a substrate include a spinner method, a printing method, a dipping method, a dropping method, an inkjet method, etc. These methods are also applicable to the present invention.

[0168] The heat drying step is generally known to be a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, etc. The heat drying step is preferably carried out at a temperature within a range in which the solvent can evaporate, and more preferably at a temperature relatively lower than the temperature in the heat baking step. Specifically, the heat drying temperature is preferably in the range of 30°C to 150°C, more preferably in the range of 50°C to 120°C.

[0169] The heating and baking process can be carried out under conditions necessary for removing a trace amount of remaining solvent after the heating and drying process, or conditions necessary for the polyamic acid or its derivative to undergo an imidization reaction. For baking of the coating film, a method of heating in an oven or an infrared furnace, a method of heating on a hot plate, etc. are generally known. These methods can also be applied in the present invention. In general, the baking is preferably carried out at a temperature of about 90 to 300°C for 1 minute to 3 hours, more preferably 120 to 280°C, and even more preferably 150 to 250°C.

[0170] When it is important to improve the anisotropy of the film or the afterimage characteristics when a liquid crystal display device is manufactured, it is preferable to raise the temperature gradually in the heating step, for example, by heating and baking at different temperatures multiple times while raising the temperature stepwise, or by heating while changing the temperature from a low temperature to a high temperature. Also, both heating methods may be combined.

[0171] When firing is performed multiple times at different temperatures, multiple heating devices set to different temperatures may be used, or one heating device may be used and the temperature may be changed sequentially to different temperatures.

[0172] When firing is performed multiple times at different temperatures, the initial firing temperature is preferably 90 to 180 ° C, and the final temperature is preferably 185 ° C to 300 ° C. For example, it is preferable to heat and fire at 110 ° C and then heat and fire at 220 ° C, heat and fire at 110 ° C and then heat and fire at 230 ° C, heat and fire at 130 ° C and then heat and fire at 220 ° C, heat and fire at 150 ° C and then heat and fire at 200 ° C, heat and fire at 150 ° C and then heat and fire at 220 ° C, heat and fire at 150 ° C and then heat and fire at 230 ° C, or heat and fire at 170 ° C and then heat and fire at 200 ° C. It is also preferable to heat and fire the product in more stages while gradually increasing the temperature. When heating and firing is performed in two or more stages with different heating temperatures, the heating time in each heating step is preferably 5 to 30 minutes.

[0173] When firing is performed by changing the temperature from a low temperature to a high temperature, the initial temperature is preferably 90 to 180°C. The final temperature is preferably 185 to 300°C, more preferably 190 to 230°C. The heating time is preferably 5 to 60 minutes, more preferably 20 to 60 minutes. The temperature rise speed can be, for example, 0.5°C / min to 40°C / min. The temperature rise speed during the temperature rise does not have to be constant.

[0174] In the method for forming a liquid crystal alignment film of the present invention, a known photoalignment method can be suitably used as a means for imparting anisotropy to a thin film in order to align liquid crystals in one direction relative to the horizontal and / or vertical directions.

[0175] A method for forming the liquid crystal alignment film of the present invention using a photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using the photo-alignment method can be formed by irradiating light onto a thin film after heating and drying a coating film, thereby imparting anisotropy to the thin film, and then heating and baking the film. Alternatively, the liquid crystal alignment film can be formed by heating and drying a coating film, heating and baking the film, and then irradiating the thin film with linearly polarized or unpolarized light. From the viewpoint of liquid crystal alignment, it is preferable that the light irradiation step is performed before the heating and baking step.

[0176] Furthermore, in order to increase the liquid crystal alignment ability of the liquid crystal alignment film, the coating film can be irradiated with light while being heated. The light irradiation can be performed in the step of drying the coating film by heating or in the step of baking the coating film by heating, or can be performed between the steps of drying the coating film by heating and baking the coating film by heating. The heating temperature when irradiating light in the step of drying or baking the coating film can be determined by referring to the description of the drying or baking step above. The heating temperature when irradiating light between the drying and baking steps is preferably in the range of 30°C to 150°C, more preferably in the range of 50°C to 110°C.

[0177] The light may be, for example, ultraviolet light or visible light having a wavelength of 150 to 800 nm, preferably ultraviolet light having a wavelength of 200 to 400 nm. Linearly polarized light or non-polarized light may be used. The light is not particularly limited as long as it can impart liquid crystal alignment ability to the thin film, but linearly polarized light is preferred when a strong alignment control force is desired to be exerted on the liquid crystal.

[0178] The irradiation dose of the linearly polarized light in the light irradiation step is 0.05 to 10 J / cm 2 is preferably 0.1 to 5 J / cm 2 is more preferable. The irradiation angle of the linearly polarized light to the film surface is not particularly limited, but in order to exert a strong alignment control force on the liquid crystal, it is preferable that the irradiation angle is as perpendicular as possible to the film surface from the viewpoint of shortening the alignment treatment time. In addition, the liquid crystal alignment film of the present invention can align the liquid crystal in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating the linearly polarized light.

[0179] The light source used in the light irradiation process can be, without limitation, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a deep UV lamp, a halogen lamp, a metal halide lamp, a high power metal halide lamp, a xenon lamp, a mercury xenon lamp, an excimer lamp, a KrF excimer laser, a fluorescent lamp, an LED lamp, a sodium lamp, a microwave excited electrodeless lamp, and the like.

[0180] The liquid crystal alignment film of the present invention can be suitably obtained by a method including steps other than the steps described above.

[0181] The liquid crystal alignment film of the present invention does not necessarily require a step of washing the film after baking or light irradiation with a washing solution, but a washing step can be provided for the convenience of other steps. Examples of the washing method using a washing solution include brushing, jet spray, steam washing, and ultrasonic washing. These methods may be performed alone or in combination. As the washing solution, pure water or various alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, aromatic hydrocarbons such as benzene, toluene, and xylene, halogen-based solvents such as methylene chloride, and ketones such as acetone and methyl ethyl ketone can be used, but are not limited to these. Of course, these washing solutions are sufficiently purified and have few impurities. Such a washing method can also be applied to the washing step in the formation of the liquid crystal alignment film of the present invention.

[0182] In order to enhance the liquid crystal alignment ability of the liquid crystal alignment film of the present invention, an annealing treatment using heat or light can be used before or after the heating and baking process, or before or after irradiation with polarized or unpolarized light. In the annealing treatment, the annealing temperature is 30 to 180°C, preferably 50 to 150°C, and the time is preferably 1 minute to 2 hours. Examples of annealing light used in the annealing treatment include UV lamps, fluorescent lamps, and LED lamps. The amount of light irradiation is 0.3 to 10 J / cm. 2 It is preferable that:

[0183] When a liquid crystal alignment film is formed from the liquid crystal alignment agent of the present invention using a rubbing method, it can be obtained by a conventional method for producing a liquid crystal alignment film from a liquid crystal alignment agent for rubbing. For example, the method described in International Publication No. 2019 / 031604 can be referenced.

[0184] The thickness of the liquid crystal alignment film of the present invention is not particularly limited, but is preferably 10 to 300 nm, more preferably 30 to 150 nm. The thickness of the liquid crystal alignment film of the present invention can be measured by a known thickness measuring device such as a step gauge or an ellipsometer.

[0185] The liquid crystal alignment film of the present invention is characterized by having a particularly large anisotropy of alignment. The magnitude of such anisotropy can be evaluated by a method using polarized IR described in JP-A-2005-275364, etc., and can also be evaluated by a method using ellipsometry. In detail, the retardation value of the liquid crystal alignment film can be measured by a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of orientation of the polymer main chain.

[0186] The liquid crystal alignment film of the present invention can be used for controlling the alignment of liquid crystal compositions for liquid crystal displays such as smartphones, tablets, in-vehicle monitors, and televisions. In addition to the alignment of liquid crystal compositions for liquid crystal displays, the film can be used for controlling the alignment of all other liquid crystal materials, such as optical compensation materials and wideband variable phase shifters in the microwave and millimeter wave bands using liquid crystals. In addition, since the liquid crystal alignment film of the present invention has a large anisotropy, it can be used alone for optical compensation materials.

[0187] <Liquid crystal display element> The liquid crystal display element of the present invention is characterized by having the liquid crystal alignment film of the present invention, and can realize high display quality due to its afterimage characteristics, contrast, and speed of relaxation of accumulated charges.

[0188] The liquid crystal display element of the present invention will be described in detail. The present invention is a liquid crystal display element having a pair of substrates arranged opposite to each other, electrodes formed on one or both of the opposing surfaces of each of the pair of substrates, a liquid crystal alignment film formed on the opposing surface of each of the pair of substrates, a liquid crystal layer formed between the pair of substrates, a pair of polarizing films arranged to sandwich the opposing substrates, a backlight, and a driving device, in which the liquid crystal alignment film is composed of the liquid crystal alignment film of the present invention.

[0189] The electrode is not particularly limited as long as it is an electrode formed on one side of the substrate. Examples of such electrodes include transparent electrodes such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and IGZO (In-Ga-Zn Oxide) electrodes, and metal deposition films. The electrode may be formed on the entire surface of one side of the substrate, or may be formed in a desired shape, for example, patterned. Examples of the desired shape of the electrode include a comb-shaped or zigzag structure. The electrode may be formed on one of the pair of substrates, or may be formed on both substrates. The form of electrode formation differs depending on the type of liquid crystal display element. For example, in the case of an IPS mode liquid crystal display element (horizontal electric field type liquid crystal display element), an electrode is disposed on one of the pair of substrates, and in the case of other liquid crystal display elements, an electrode is disposed on both of the pair of substrates. The liquid crystal alignment film is formed on the substrate or the electrode.

[0190] In the case of a homogeneous alignment liquid crystal display element (e.g., IPS mode, FFS mode, etc.), the structure includes at least a backlight, a first polarizing film, a first substrate, a first liquid crystal alignment film, a liquid crystal layer, a second substrate, and a second polarizing film from the backlight side, and the polarizing axis of the polarizing film is set so that the polarizing axis of the first polarizing film (direction of polarized light absorption) crosses (preferably perpendicular) with the polarizing axis of the second polarizing film. At this time, the polarizing axis of the first polarizing film can be set so that it is parallel to the liquid crystal alignment direction or perpendicular to the liquid crystal alignment direction. A liquid crystal display element in which the polarizing axis of the first polarizing film is set so that it is parallel to the liquid crystal alignment direction is called O-mode, and a liquid crystal display element in which it is set so that it is perpendicular to the liquid crystal alignment direction is called E-mode. The liquid crystal alignment film of the present invention can be applied to either O-mode or E-mode, and can be selected according to the purpose.

[0191] Many photoisomerization materials use compounds with dichroism. Therefore, when the polarization axis of the polarized light irradiated to impart anisotropy to the liquid crystal alignment agent is aligned parallel to the polarization axis of the polarized light from the polarizing film arranged on the backlight side (when the liquid crystal alignment agent of the present invention is used, the O-mode arrangement is used), the transmittance of the liquid crystal alignment film in the light absorption wavelength range increases. Therefore, the transmittance of the liquid crystal display element can be further improved.

[0192] The liquid crystal layer is formed by sandwiching a liquid crystal composition between the pair of substrates on which the liquid crystal alignment film is formed, and when the liquid crystal layer is formed, a spacer such as fine particles or a resin sheet that is interposed between the pair of substrates to form an appropriate gap can be used as necessary.

[0193] Known methods for forming a liquid crystal layer include a vacuum injection method and an ODF (One Drop Fill) method.

[0194] In the vacuum injection method, a gap (cell gap) is provided so that the liquid crystal alignment film surfaces face each other, and a sealant is printed leaving an injection port for the liquid crystal, and then the substrates are bonded together. After the liquid crystal is injected into the cell gap defined by the substrate surface and the sealant using a vacuum pressure difference, the injection port is sealed to produce a liquid crystal display element.

[0195] In the ODF method, a sealant is printed on the outer periphery of the liquid crystal alignment film of one of the pair of substrates, liquid crystal is dropped on the area inside the sealant, and then the other substrate is attached so that the liquid crystal alignment film faces the other substrate. The liquid crystal is then spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby producing a liquid crystal display element.

[0196] In addition to UV curing types, heat curing types are also known as sealants used for bonding substrates. The sealant can be printed by screen printing, for example.

[0197] The liquid crystal composition is not particularly limited, and various liquid crystal compositions having positive or negative dielectric anisotropy can be used. Liquid crystal compositions having positive dielectric anisotropy (positive type liquid crystal compositions) are disclosed in Japanese Patent No. 3086228, Japanese Patent No. 2635435, JP-A-5-501735, JP-A-8-157826, JP-A-8-231960, JP-A-9-241644 (EP885272A1), JP-A-9-302346 (EP806466A1), JP-A-8-199168 (EP72299 8A1), JP-A-9-235552, JP-A-9-255956, JP-A-9-241643 (EP885271A1), JP-A-10-204016 (EP844229A1), JP-A-10-204436, JP-A-10-231482, JP-A-2000-087040, JP-A-2001-48822, etc.

[0198] Preferable examples of the liquid crystal composition having negative dielectric anisotropy (negative type liquid crystal composition) include JP-A-57-114532, JP-A-2-4725, JP-A-4-224885, JP-A-8-40953, JP-A-8-104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-236990, JP-A-10-236992, JP-A-10-236993, JP-A-10-236994, JP-A-10-237000, JP-A-10-237004, JP-A-10-237024, JP-A-10-237035, JP-A-10-237075, JP-A-10-237076 ...7076, JP-A-10-237076, 37076, JP-A-10-237448 (EP967261A1), JP-A-10-287874, JP-A-10-287875, JP-A-10-291945, JP-A-11-029581, JP-A-11-080049, JP-A-2000-256307, JP-A-2001-019965, JP-A-2001-072626, JP-A-2001-192657, JP-A-2010-037428, WO 2011 / 024666, WO 2010 / 072370, JP-T-2010-537010, JP-A-2012-077201, JP-A-2009-084362, and the like.

[0199] There is no problem in using a liquid crystal composition having a positive or negative dielectric anisotropy by adding one or more optically active compounds.

[0200] For example, the liquid crystal composition used in the liquid crystal display element of the present invention may further contain additives, for example, from the viewpoint of improving the alignment. Such additives include photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, defoamers, polymerization initiators, and polymerization inhibitors. Preferred photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, defoamers, polymerization initiators, and polymerization inhibitors include compounds disclosed in International Publication WO 2015 / 146330 and the like.

[0201] Polymerizable compounds can be mixed into the liquid crystal composition to be compatible with a liquid crystal display device in the PSA (Polymer Sustained Alignment) mode. Preferred examples of the polymerizable compounds are compounds having polymerizable groups such as acrylate, methacrylate, vinyl compounds, vinyloxy compounds, propenyl ethers, epoxy compounds (oxirane, oxetane), vinyl ketones, etc. Preferred compounds include those disclosed in International Publication No. 2015 / 146330 and the like.

Examples

[0202] Hereinafter, the present invention will be described with reference to examples. The evaluation methods and compounds used in the examples are as follows.

[0203] <Weight-average molecular weight (Mw)> The weight-average molecular weight of the polyamic acid was measured by the GPC method using a 2695 separation module and a 2414 differential refractometer (manufactured by Waters), and was determined by conversion to polystyrene. The obtained polyamic acid was diluted with a phosphoric acid-DMF mixed solution (phosphoric acid / DMF = 0.6 / 100: weight ratio) so that the polyamic acid concentration became about 2% by weight. As the column, HSPgel RT MB-M (manufactured by Waters) was used, and the measurement was carried out under the conditions of a column temperature of 50°C and a flow rate of 0.40 mL / min using the above mixed solution as the eluent. As the standard polystyrene, TSK standard polystyrene manufactured by Tosoh Corporation was used.

[0204] <AC afterimage measurement · Contrast measurement> The AC afterimage was measured according to the method described in International Publication No. 2000 / 43833. Specifically, the luminance-voltage characteristics (B-V characteristics) of the fabricated liquid crystal cell were measured and taken as the luminance-voltage characteristics before stress application: B(before). Next, an alternating current of 4.5 V and 60 Hz was applied to the liquid crystal cell for 20 minutes, followed by a 1-second short circuit, and then the luminance-voltage characteristics (B-V characteristics) were measured again. This was taken as the luminance-voltage characteristics after stress application: B(after). Here, the luminance at a voltage of 1.3 V in each measured luminance-voltage characteristic was used, and the luminance change rate ΔB(%) was obtained using the following formula. The smaller the value of ΔB(%), the more the occurrence of the AC afterimage can be suppressed, that is, the better the afterimage characteristics. If ΔB is 3% or less, it can be said that the afterimage characteristics are good. However, in recent years, the requirements for afterimage characteristics have been further increased, and a lower value is preferred. ΔB(%) = {[B(after) - B(before)] / B(before)} × 100 Also, the contrast (CR) was obtained using the ratio of the minimum luminance to the maximum luminance in the B-V characteristics before stress application. The larger the value of CR, the clearer the light and dark display, which means better contrast, and it can be said to have excellent contrast when it is 3000 or more. CR = B(before) max / B(before) min In the formula, B(before) max represents the maximum luminance in the B-V characteristics before stress application, and B(before) min represents the minimum luminance in the B-V characteristics before stress application. <Evaluation of DC Relaxation Characteristics> The liquid crystal cell was driven at AC2.5V for 10 minutes, then while driving at AC2.5V, DC0.3V was applied for 20 minutes, and the DC application was stopped and the cell was driven at AC2.5V. During this time, the transmittance was measured. The relaxation time was calculated as the time from the end of the DC application until the accumulated charge was relaxed and the transmittance became within the value obtained by adding 0.1% to the transmittance immediately after the start of driving. The shorter the relaxation time, the better the DC relaxation characteristics. If the relaxation time is less than 5 minutes, it is evaluated as "◎", if it is 5 minutes or more but less than 10 minutes, it is evaluated as "○", if it is 10 minutes or more but less than 20 minutes, it is evaluated as "△", and if it is 20 minutes or more, it is evaluated as "×". It can be said that the DC relaxation characteristics are excellent if it is "◎", "○", or "△".

[0205] <Diamines> TIFF0007647448000098.tif21145 TIFF0007647448000099.tif5494

[0206] <Tetracarboxylic acid dianhydrides> TIFF0007647448000100.tif51127 The value of m in the compound represented by formula (3-1) is shown in Table 1.

[0207] <Solvent> NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether)

[0208] <Preparation of Varnish> The varnish used in this example was prepared by the following procedure. Here, varnishes A1 to A3 and B1 prepared in varnish preparation examples 1 to 4 are solutions of polyamic acid having a photoreactive structure using a compound represented by formula (1) as a raw material. Varnishes A1 to A3 are solutions of polyamic acid of the present invention using at least one of a compound represented by formula (2) and a compound represented by formula (3) as a raw material, and optionally further using a compound represented by formula (4). Varnish B1 is a solution of polyamic acid for comparison that does not use these compounds as raw materials. Varnishes D1 to D2 for blending prepared in varnish preparation examples 5 to 6 are solutions of polyamic acid obtained without using a compound having a photoreactive structure as a raw material, and are used by blending with varnishes A1 to A3 or B1.

[0209] [Varnish Preparation Example 1] Preparation of Varnish A1 A 100 mL three-neck flask equipped with a stirring blade and a nitrogen inlet tube was charged with diamine isomer mixture 1 (1.394 g), and NMP (17.0 g) was added and stirred. To this solution, a compound represented by formula (2-1) (1.429 g) and a compound represented by formula (AN-1-1) (0.177 g) were added and stirred at room temperature for 12 hours. NMP (15.0 g) and BC (15.0 g) were added thereto, and the solution was heated and stirred at 70°C until the weight average molecular weight of the solute polymer reached the desired weight average molecular weight, to obtain varnish A1 with a weight average molecular weight of the solute of approximately 18,000 and a polymer concentration of 6 wt%.

[0210] [Varnish Preparation Examples 2 to 6] Preparation of Varnishes A2 to A3, Varnish B1, and Varnishes D1 to D2 Except for changing the compounds used as diamines and tetracarboxylic dianhydrides as shown in Table 1, varnishes A2 to A3, varnish B1, and varnishes D1 to D2 with a polymer concentration of 6% by weight were prepared in the same manner as in Preparation Example 1. In addition, in varnishes D1 to D2, the heating and stirring conditions were adjusted so that the weight-average molecular weight of the polymer was about 50,000. The weight-average molecular weight of the generated polymer is shown in Table 1. In addition, in Preparation Examples in which two or more compounds are listed as diamines in Table 1, it means that all of the compounds were used together as diamines, and in Preparation Examples in which two or more compounds are listed as tetracarboxylic dianhydrides, it means that all of the compounds were used together as tetracarboxylic dianhydrides. The numbers in square brackets represent the compounding ratio (mol%), and blanks mean that the compound corresponding to that column was not used. In addition, the weight-average molecular weight is listed to two significant digits, and the last three digits are rounded off.

[0211] [Table 1] TIFF0007647448000101.tif71150

[0212] [Example 1] <Preparation of Liquid Crystal Alignment Agent> Varnish A1 was diluted with a NMP·BC mixed solution (NMP / BC=7 / 3 weight ratio) so that the polymer concentration was 4 wt %, and stirred to prepare liquid crystal alignment agent E1. <Contrast measurement, AC image retention measurement, DC relaxation characteristic evaluation> Liquid crystal alignment agent E1 was applied to a glass substrate with FFS electrodes and a glass substrate with column spacers by the spinner method. After application, the substrate was heated at 60°C for 80 seconds to evaporate the solvent, and then the substrate was irradiated with linearly polarized ultraviolet light from a vertical direction through a polarizing plate using a Multilight ML-501C / B manufactured by Ushio Inc. The exposure energy at this time was measured using an ultraviolet integrating light meter UIT-150 (receiver: UVD-S254) manufactured by Ushio Inc., and was 0.5 J / cm at a wavelength of 254 nm. 2The exposure time was adjusted so that the thickness of the alignment film was about 100 nm. Next, the two substrates on which the liquid crystal alignment films were formed were bonded together with the surfaces on which the liquid crystal alignment films were formed facing each other and a gap was provided between the facing liquid crystal alignment films for injecting the liquid crystal composition. At this time, the polarization directions of the linearly polarized light irradiated on each liquid crystal alignment film were parallel to each other. Positive liquid crystal composition A was injected into these cells to prepare liquid crystal cells (liquid crystal display elements) with a cell thickness of 5 μm.

[0213] <Positive Liquid Crystal Composition A> TIFF0007647448000102.tif18097 (Physical properties) Phase transition temperature NI: 100.1°C, dielectric anisotropy Δε: 5.1, refractive index anisotropy Δn: 0.093, viscosity η: 25.6 mPa s.

[0214] Using the liquid crystal cell thus fabricated, AC image retention measurement, contrast measurement, and DC relaxation characteristic evaluation were performed according to the above-mentioned evaluation method "AC image retention measurement, contrast measurement, and DC relaxation characteristic evaluation." The results were ΔB of 1.8%, CR of 3600, and DC relaxation characteristic of ◎.

[0215] [Example 2] to [Example 3], [Comparative Example 1] Except for using the varnishes shown in Table 2 instead of varnish A1, the same operation as in Example 1 was performed to prepare liquid crystal alignment agents E2 to E3 and F1. Using the prepared liquid crystal alignment agents, the same operation as in Example 1 was performed to measure contrast, measure AC afterimage, and evaluate DC relaxation characteristics. The results are shown in Table 2 together with the results of Example 1.

[0216] [Table 2] TIFF0007647448000103.tif33135

[0217] In Examples 1 to 3, in which liquid crystal alignment agents E1 to E3 prepared from varnishes A1 to A3 using the compounds represented by formula (1) and formula (2) or formula (3) or formula (4) of the present invention were used, the contrast value was 3000 or more, which was excellent. In addition, the ΔB value was small at 2% or less, which was excellent in afterimage characteristics. Good results were obtained in terms of DC relaxation characteristics, and a liquid crystal display element that satisfied all characteristics, including contrast, afterimage characteristics, and DC relaxation characteristics, was obtained. On the other hand, in Comparative Example 1, in which the compounds represented by formula (2) or formula (3) or formula (4) of the present invention were not used, a liquid crystal display element with good DC relaxation characteristics was not obtained.

[0218] [Example 4] Varnish A1 and varnish D1 were blended in a weight ratio of 3:7, and then diluted with an NMP·BC mixed solution (NMP / BC=7 / 3 weight ratio) to give a polymer concentration of 4 wt%, followed by stirring to prepare liquid crystal alignment agent E4. Using the liquid crystal alignment agent E4, the same operations as in Example 1 were carried out to measure the contrast, measure the AC afterimage, and evaluate the DC relaxation characteristics.

[0219] [Examples 5] to [Examples 7], [Comparative Example 2] Liquid crystal alignment agents E5 to E7, and F2 were prepared in the same manner as in Example 4, except that the varnishes shown in Table 3 were used instead of varnish A1 and varnish D1, and the blend ratios were changed to those shown in Table 3. Using the prepared liquid crystal alignment agents, contrast measurement, AC image retention measurement, and evaluation of DC relaxation characteristics were performed in the same manner as in Example 4. The varnishes used, the blend ratios, and the results are shown in Table 3 together with those of Example 4. The values ​​in square brackets in Table 3 are the blend ratios (weight ratios).

[0220] [Table 3] TIFF0007647448000104.tif60150

[0221] In Examples 4 to 7, in which varnishes A1 to A3 using the compound represented by formula (2), formula (3) or formula (4) of the present invention and blend-type liquid crystal alignment agents E4 to E7 blended with D1 or D2 were used, the contrast value was 3000 or more, and excellent contrast was shown. In addition, the ΔB value was small at 3% or less, and excellent afterimage characteristics were shown. Good results were obtained in the DC relaxation characteristics, and a liquid crystal display element satisfying all characteristics, including contrast, afterimage characteristics and DC relaxation characteristics, was obtained. On the other hand, in Comparative Example 2 in which the compound represented by formula (2), formula (3) or formula (4) of the present invention was not used, a liquid crystal display element having good DC relaxation characteristics was not obtained. [Industrial Applicability]

[0222] By using a liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention, a liquid crystal display device having good contrast and afterimage characteristics and fast relaxation of accumulated charges can be obtained. The liquid crystal aligning agent of the present invention can be suitably applied to a horizontal electric field type liquid crystal display device.

Claims

1. A liquid crystal aligning agent comprising at least one polymer and a solvent, wherein at least one of the polymers is a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine, A liquid crystal aligning agent, wherein the diamines include at least one compound represented by formula (1), and the tetracarboxylic dianhydrides include at least one compound selected from the group consisting of compounds represented by formula (2) or (3) and derivative compounds thereof. In formula (1), R １ and R ２ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; R １ and R ２ may be taken together to form an optionally substituted methylene group, Each X is independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; n represents an integer from 0 to 4; In formula (2) and formula (3), R 3 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and in formula (3), W is an alkylene group having 1 to 12 carbon atoms, and the -(CH ２ ) ２ One or more non-adjacent -'s may be replaced with either -O- or -NH-; In formula (1), formula (2) and formula (3), a group that is not fixed to any of the carbon atoms constituting a ring can be bonded to any available carbon atom in the ring.

2. The liquid crystal aligning agent according to claim 1, wherein the compound represented by formula (1) is a compound represented by formula (1-2): In formula (1-2), R １ and R ２ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; R １ and R ２ may be joined together to form an optionally substituted methylene group.

3. 3. The liquid crystal aligning agent according to claim 1, wherein in the formula (1) or (1-2), the two esters are arranged in trans on the cyclopropane ring.

4. The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the tetracarboxylic dianhydride comprises at least one compound selected from the group consisting of compounds represented by formula (2-1) or formula (3-1) and derivative compounds thereof. In formula (3-1), m is an integer of 1 to 8.

5. The liquid crystal aligning agent according to any one of claims 1 to 4, wherein the diamines include a compound represented by formula (4): In formula (4), R 4 each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms; and k represents an integer of 1 to 6.

6. The liquid crystal aligning agent according to claim 5, wherein the compound represented by formula (4) is a compound represented by formula (4-1):

7. The liquid crystal aligning agent according to any one of claims 1 to 6, further comprising an additive.

8. A liquid crystal alignment film formed from the liquid crystal aligning agent according to any one of claims 1 to 7.

9. A liquid crystal device comprising the liquid crystal alignment film according to claim 8.

10. A method for producing a liquid crystal alignment film, comprising the steps of: applying the liquid crystal aligning agent according to any one of claims 1 to 7 to a substrate; and irradiating the coating with polarized ultraviolet light.

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