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

Abstract

The present invention provides a liquid crystal alignment agent, which can obtain a liquid crystal alignment film that maintains a voltage holding ratio even after exposure to high temperature and high humidity. The liquid crystal alignment agent of the present invention is characterized in that it contains at least one polymer selected from the group consisting of a polyimide precursor and a polyimide, the polyimide precursor being obtained by polymerizing any of the following diamine components (1) and diamine components (2) with a tetracarboxylic acid component, and the polyimide being obtained by imidizing the polyimide precursor. Diamine component (1): a diamine component containing a diamine having a protective group substituted by a hydrogen atom by heat and a diamine having a siloxane skeleton. Diamine component (2): a diamine component containing a diamine having a protective group substituted by a hydrogen atom by heat and a siloxane skeleton.

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 liquid crystal alignment film. Background Art

[0002] In a liquid crystal display element, a liquid crystal alignment film plays the role of orienting the liquid crystal in a certain direction. As a liquid crystal alignment film, a polyimide-based liquid crystal alignment film has been mainly used so far, which is formed by applying a liquid crystal alignment agent having a polyimide precursor such as polyamic acid or a solution of a soluble polyimide as a main component to a glass substrate and firing it.

[0003] As liquid crystal display elements become more functional, liquid crystal alignment films are required to have, in addition to excellent liquid crystal orientation and a stable pretilt angle, a high voltage holding ratio, less residual charge when a DC voltage is applied, and / or a fast relaxation of residual charge accumulated by the DC voltage.

[0004] In order to meet the above-mentioned requirements, various proposals have been made. For example, Patent Document 1 proposes a liquid crystal aligning agent composed of an imidized polymer satisfying the following formula (1).

[0005]

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-179429 Summary of the invention

[0009] Problems to be solved by the invention

[0010] With the recent improvement in the performance of liquid crystal display elements, liquid crystal display elements are used for large-screen and high-definition liquid crystal television vehicle applications, such as vehicle navigation systems, instrument panels, etc. In such applications, in addition to requiring good initial characteristics, it is also required that the voltage holding ratio is not easily reduced even after long-term exposure to high temperature and high humidity.

[0011] In addition, when a liquid crystal alignment agent with a high imidization rate is used, a high voltage holding rate is easily obtained, but when the solubility in the solvent is reduced or when printing on a substrate, there is a problem that polyimide is precipitated due to moisture absorption and the varnish is easily whitened. Therefore, even when a liquid crystal alignment agent with a low imidization rate is used, it is required that the voltage holding rate of the liquid crystal alignment film is not easily reduced.

[0012] However, there is no disclosure on the voltage retention after exposure to high temperature and high humidity in Patent Document 1. Furthermore, the Examples of Patent Document 1 disclose only the case of using a liquid crystal aligning agent having a high imidization rate.

[0013] The present invention is completed in view of the above situation, and its purpose is to provide a liquid crystal alignment agent, which can obtain a liquid crystal alignment film that maintains a voltage holding ratio even after being exposed to high temperature and high humidity. In addition, the purpose of the present invention is to provide a liquid crystal alignment agent, which can obtain a liquid crystal alignment film that maintains a voltage holding ratio even when the imidization ratio is low.

[0014] Solutions for solving problems

[0015] Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a liquid crystal aligning agent containing a specific polymer satisfies the above-mentioned problems.

[0016] The present invention has been accomplished based on the above findings, and the following contents are set as the gist.

[0017] A liquid crystal aligning agent characterized by containing at least one polymer selected from the group consisting of a polyimide precursor and a polyimide obtained by imidating the polyimide precursor, wherein the polyimide precursor is obtained by polymerizing any of the following diamine components (1) and (2) with a tetracarboxylic acid component.

[0018] Diamine component (1): a diamine component containing a diamine having a protective group substituted with a hydrogen atom by heat and a diamine having a siloxane skeleton.

[0019] Diamine component (2): a diamine component containing a diamine having a protective group substituted with a hydrogen atom by heat and a siloxane skeleton.

[0020] Effects of the Invention

[0021] According to the liquid crystal alignment agent of the present invention, a liquid crystal alignment film that maintains a voltage holding ratio can be obtained even after exposure to high temperature and high humidity. In addition, according to the liquid crystal alignment agent of the present invention, a liquid crystal alignment film that maintains a voltage holding ratio can be obtained even when the imidization ratio is low. In addition, the liquid crystal alignment agent of the present invention is also excellent in solubility and sealing adhesion. DETAILED DESCRIPTION

[0022] <Specific polymers>

[0023] The liquid crystal aligning agent of the present invention contains at least one polymer (hereinafter also referred to as a specific polymer) selected from the group consisting of a polyimide precursor obtained by polymerizing any of the following diamine components (1) and (2) and a tetracarboxylic acid component, and a polyimide obtained by imidating the polyimide precursor.

[0024] Diamine component (1): a diamine component containing a diamine having a protective group substituted with a hydrogen atom by heat and a diamine having a siloxane skeleton.

[0025] Diamine component (2): a diamine component containing a diamine having a protective group substituted with a hydrogen atom by heat and a siloxane skeleton.

[0026] <Diamine component (1)>

[0027] The diamine having a protective group that is substituted by a hydrogen atom by heat in the diamine component (1) is, for example, a diamine represented by the following formula [1]. The diamine having a siloxane skeleton in the diamine component (1) is, for example, a diamine represented by the following formula [2]. In the diamine component (1), the diamine having a protective group that is substituted by a hydrogen atom by heat may be a diamine represented by the following formula [1], and the diamine having a siloxane skeleton may be a diamine represented by the following formula [2].

[0028] (Diamine represented by formula [1])

[0029] The diamine represented by formula [1] is the following diamine.

[0030]

[0031] (In formula [1], X D represents an organic group having 1 to 50 carbon atoms and having at least one structure selected from the group consisting of the following formula [1a], formula [1b] and formula [1c], 1 and A 2 Each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. )

[0032]

[0033] (In formula [1a] to formula [1c], X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms. d represents a single bond or an organic group having 1 to 20 carbon atoms. e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms. D represents a protecting group that is substituted by a hydrogen atom by heat. * represents a bonding bond.

[0034] Here, in the present invention, "a protecting group substituted by a hydrogen atom by heat" means a protecting group detached by heat and substituted by a hydrogen atom. The temperature at which the protecting group is detached by heat and substituted by a hydrogen atom is the calcination temperature when the liquid crystal alignment film is prepared, preferably 150 to 300°C, more preferably 200 to 270°C. As the protecting group (D), a protecting group represented by the following formula [P] is preferred.

[0035]

[0036] (Where X A represents a structure selected from the group consisting of the following formulas [a-1] to [a-6], R 1 represents an alkylene group having 1 to 5 carbon atoms. )

[0037]

[0038] Specifically, as the diamine represented by the formula [1], it is preferable to use the diamine represented by the following formula [1a-1] to the formula [1c-1].

[0039]

[0040] In formula [1a-1], X 1 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 )CO-、-CH 2 At least one of -O-, -COO- and -OCO-. 1 , R 2 and R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In particular, a single bond, -O-, -CONH-, -NHCO-, -COO- or -OCO- is preferred.

[0041] In formula [1a-1], X 2 represents a single bond or an alkylene group having 1 to 10 carbon atoms. Among them, a single bond or an alkylene group having 1 to 5 carbon atoms is preferred. a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and more preferably represents a hydrogen atom or an organic group having 1 to 10 carbon atoms. As the organic group having 1 to 10 carbon atoms, preferably -(CH 2 ) n -COO-tBu (n represents an integer of 1 to 5, and tBu represents a tert-butyl group).

[0042] In formula [1a-1], X bIt represents a structure selected from the group consisting of the above formula [a-1] to formula [a-6].

[0043] In formula [1a-1], m represents an integer of 1 or 2. In this case, when m is 2, there is no X a p represents an integer of 1 to 4. In view of the availability of raw materials and the ease of synthesis, p is preferably 1 to 3. More preferably, it is 1 to 2. q represents an integer of 1 to 4. In view of the availability of raw materials and the ease of synthesis, q is preferably 1 to 3. More preferably, it is 1 to 2.

[0044] In formula [1b-1], X 3 and X 7 Each independently represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 )CO-、-CH 2 At least one organic group selected from the group consisting of O-, -COO- and -OCO-. 1 , R 2 and R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Among them, a single bond, -O-, -CONH-, -NHCO-, -COO- or -OCO- is preferred.

[0045] In formula [1b-1], X 4 and X 6 Each independently represents a single bond or an alkylene group having 1 to 10 carbon atoms. In particular, a single bond or an alkyl group having 1 to 5 carbon atoms is preferred.

[0046] X 5 represents a single bond or an alkylene group having 1 to 10 carbon atoms. Among them, a single bond or an alkylene group having 1 to 5 carbon atoms is preferred. c It represents a structure selected from the group consisting of the above formula [a-1] to formula [a-6].

[0047] In the formula [1b-1], r represents an integer of 1 to 4. Among them, r is preferably 1 to 3, and more preferably 1 to 2, from the viewpoint of the availability of raw materials and the ease of synthesis.

[0048] In formula [1c-1], X 8 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 )CO-、-CH 2At least one organic group selected from the group consisting of O-, -COO- and -OCO-. 1 , R 2 and R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In particular, a single bond, -O-, -CONH-, -NHCO-, -COO- or -OCO- is preferred.

[0049] In formula [1c-1], X 9 represents a single bond or an alkylene group having 1 to 10 carbon atoms, and preferably represents a single bond or an alkylene group having 1 to 5 carbon atoms. d represents a single bond or an organic group having 1 to 20 carbon atoms. d A single bond or an organic group having 1 to 10 carbon atoms is preferred. d More preferably, X represents a single bond or a carbon atom (>CH-). e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms. d There is no X in the case of a single bond. e Among them, a hydrogen atom or NH—COO—tBu (tBu represents a tert-butyl group) is preferred.

[0050] In formula [1c-1], X f represents a structure selected from the group consisting of the above formula [a-1] to formula [a-6]. n represents an integer of 1 to 4. In view of the availability of raw materials and the ease of synthesis, n is preferably 1 to 3, and more preferably 1 to 2. s represents an integer of 1 to 4. In view of the availability of raw materials and the ease of synthesis, s is preferably 1 to 3, and more preferably 1 to 2. t represents an integer of 1 to 4. In view of the availability of raw materials and the ease of synthesis, t is preferably 1 to 3, and more preferably 1 to 2.

[0051] In formula [1a-1] to formula [1c-1], A 1 ~A 6 Each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

[0052] More specifically, examples of the diamine represented by formula [1] include diamines represented by the following formulas [1d-1] to [1d-11].

[0053]

[0054] (In formula [1d-1] to formula [1d-5], R 1 ~R 7 Each independently represents at least one structure selected from the group consisting of the following formulae [a-1] to [a-6], wherein in formulae [1d-1] to [1d-5], A1 ~A 10 Each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. )

[0055]

[0056] (In formula [a-2], R 1 represents an alkylene group having 1 to 5 carbon atoms. )

[0057]

[0058] (In formula [1d-6] to formula [1d-9], R 8 ~R 14 Each independently represents at least one structure selected from the group consisting of the structures represented by the above formulas [a-1] to [a-6], and in the formulas [1d-6] to [1d-9], A 11 ~A 18 each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms).

[0059] Among them, as the diamine represented by formula [1], it is preferable to use the diamine represented by the above formula [1d-1] to formula [1d-5].

[0060] Furthermore, as the diamine represented by the formula [1], diamines represented by the following formulas [1d-10] and [1d-11] can be used.

[0061]

[0062] (In formula [1d-10] and formula [1d-11], R 15 ~R 18 Each independently represents at least one structure selected from the group consisting of the structures represented by the above formulas [a-1] to [a-6], and in the formula [1d-11], A 19 and A 20 Each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. )

[0063] The content of the diamine represented by formula [1] is preferably 5 to 70 mol% in 100 mol% of the total diamine components. Among them, 5 to 30 mol% is preferred, and 5 to 20 mol% is more preferred.

[0064] The diamine represented by formula [1] can be used alone or in combination of two or more depending on the solubility of the specific polymer in the solvent, the coating properties of the liquid crystal aligning agent, and the characteristics such as the liquid crystal alignment, voltage holding ratio, and stored charge when the liquid crystal aligning film is formed.

[0065] (Diamine represented by formula [2])

[0066] The diamine represented by formula [2] is the following diamine.

[0067]

[0068] (In formula [2], R 1 , R 2 , R 3 , R 4 Each independently represents a methyl group or an ethyl group. 1 and X 2 P each independently represents a single bond, -NHCO-, -CONH-, -COO- or -OCO-. 1 and P 2 Respectively represent -NH 2 or the structures represented by the following formulas [Pa] to [Pb]. n1 and n2 each independently represent an integer of 0 to 6. m represents an integer of 1 to 5. Wherein, the phenyl groups of formulas [Pa] to [Pb] are optionally substituted by halogen.)

[0069]

[0070] (In formula [Pa] to formula [Pb], X D2 represents an organic group having 1 to 50 carbon atoms and having at least one structure selected from the group consisting of the following formula [2a], formula [2b] and formula [2c]. p represents an integer of 0 to 1. * represents a bonding bond. )

[0071]

[0072] (In formula [2a] to formula [2c], X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms. d represents a single bond or an organic group having 1 to 20 carbon atoms. e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms. D represents a protecting group that is substituted by a hydrogen atom by heat. * represents a bonding bond.

[0073] In the above formula [2], R 1 , R 2 , R 3 , R 4 Preferably it is methyl. 1 and X 2 It is preferably a single bond, -CONH- or -COO-. 1 and P 2 Preferably -NH 2 or formula [2a]. n1 and n2 are preferably 3 or 4. m represents 1 or 2, more preferably 1.

[0074] In the diamine represented by the above formula [2], XD2 Preferably, it represents a structure selected from the following formulas [2a-1] and [2b-1].

[0075]

[0076] (In formula [2a-1], X 1 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 )CO-、-CH 2 At least one organic group selected from the group consisting of O-, -COO- and -OCO-. 1 , R 2 , R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 2 represents a single bond, an alkylene group having 1 to 10 carbon atoms, and X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X b is a group defined in the above formula [1a-1]. m represents an integer of 1 or 2. In this case, when m is 2, X a represents a hydrogen atom, p represents an integer of 1 to 4, and q represents an integer of 1 to 4.

[0077] In formula [2b-1], X 8 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 )CO-、-CH 2 At least one of the group consisting of O-, -COO- and -OCO-. 1 , R 2 , R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 9 represents a single bond, an alkylene group having 1 to 10 carbon atoms, and X d represents a single bond or an organic group having 1 to 20 carbon atoms, X e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X f represents a structure selected from the group consisting of the above formula [a-1] to formula [a-6]. n represents an integer of 1 to 4, s represents an integer of 1 to 4, and t represents an integer of 1 to 4. )

[0078] In formula [2], X D2 More preferably, it represents a group represented by the following formula (tB), and further preferably, it represents an -N-Boc group.

[0079]

[0080] (A represents a single bond or a divalent group consisting of a hydrocarbon group having 1 to 4 carbon atoms.) Preferred examples of the diamine represented by formula [2] include the following diamines.

[0081]

[0082]

[0083] The content of the diamine represented by formula [2] is preferably 1 to 50 mol% in 100 mol% of the total diamine components. Among them, it is preferably 5 to 30 mol%, and more preferably 5 to 20 mol%.

[0084] The diamine represented by formula [2] may be used alone or in combination of two or more depending on the solubility of the specific polymer in the solvent, the coating properties of the liquid crystal aligning agent, the liquid crystal alignment properties when formed into a liquid crystal aligning film, the voltage holding ratio, the stored charge and other properties.

[0085] <Diamine component (2)>

[0086] The diamine having a protective group substituted with a hydrogen atom by heat and a siloxane skeleton in the diamine component (2) is, for example, a diamine represented by the following formula [3].

[0087] (Diamine represented by formula [3])

[0088] The diamine represented by formula [3] is the following diamine.

[0089]

[0090] (In formula [3], R 1 , R 2 , R 3 , R 4 Each independently represents a methyl group or an ethyl group. X represents -NHCO-, -CONH-, -COO- or -OCO-. D2 is a group defined by the above formulas [Pa] and [Pb]. n represents an integer of 0 to 6, m represents an integer of 1 to 5. p represents an integer of 0 to 1, and q represents an integer of 0 to 1. At least one of p and q represents 1. )

[0091] In the above formula [3], X is preferably -CONH- or -COO-. m is preferably 1 or 2, and more preferably 1. 1 ~R 4 It is preferably a methyl group.

[0092] The content of the diamine represented by formula [3] is preferably 1 to 50 mol% in 100 mol% of the total diamine components. Among them, it is preferably 5 to 30 mol%, and more preferably 5 to 20 mol%.

[0093] The diamine represented by formula [3] may be used alone or in combination of two or more depending on the solubility of the specific polymer in the solvent, the coating properties of the liquid crystal aligning agent, the liquid crystal alignment properties when formed into a liquid crystal aligning film, the voltage holding ratio, the stored charge and other properties.

[0094] (Other diamines)

[0095] The diamine component (1) and the diamine component (2) for obtaining the specific polymer may contain diamines other than the diamines represented by the above formulas [1] to [3] (hereinafter also referred to as other diamines). As other diamines, firstly, the following diamines having a side chain structure can be mentioned.

[0096] (Diamine having a specific side chain structure that exhibits vertical alignment)

[0097] The diamine having a specific side chain structure that embodies vertical alignment has at least one side chain structure selected from the group represented by the following formulas [S1] to [S3]. Hereinafter, as examples of the diamine having the specific side chain structure, the diamine having the specific side chain structure represented by formulas [S1] to [S3] will be described in order.

[0098] [A]: A diamine having a specific side chain structure represented by the following formula [S1].

[0099]

[0100] In the above formula [S1], X 1 and X 2 Each independently represents a single bond, -(CH 2 ) a -(a represents an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH 3 )-, -NH-, -O-, -COO-, -OCO- or -((CH 2 ) a1 -A 1 ) m1 -. wherein a1 independently represents an integer of 1 to 15. 1 Each independently represents an oxygen atom or -COO-. m1 represents 1 or 2.

[0101] Among them, from the perspective of raw material availability and ease of synthesis, X 1 and X 2 Preferably, each independently represents a single bond, -(CH 2 )a -(a represents an integer of 1 to 15), -O-, -CH 2 O- or -COO-, more preferably represents a single bond, -(CH 2 ) a -(a represents an integer from 1 to 10), -O-, -CH 2 O-or-COO-.

[0102] In addition, in the above formula [S1], G 1 and G 2 Each independently represents a divalent cyclic group selected from the group consisting of a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group is optionally substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. m and n each independently represent an integer of 0 to 3, and the total of m and n is 1 to 4.

[0103] In the above formula [S1], R 1 represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. 1 Any hydrogen in the group may be substituted with fluorine. Examples of divalent aromatic groups having 6 to 12 carbon atoms include phenylene, biphenylene, and naphthylene. Examples of divalent alicyclic groups having 3 to 8 carbon atoms include cyclopropylene and cyclohexylene.

[0104] Therefore, as preferred specific examples of the above formula [S1], the following formulas [S1-x1] to [S1-x7] can be listed.

[0105]

[0106] In the above formulas [S1-x1] to [S1-x7], R 1 The same as the case of the above formula [S1]. p Indicates - (CH 2 ) a -(a represents an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH 3 )-, -NH-, -O-, -CH 2 O-, -COO- or -OCO-. A 1 Indicates oxygen atom or -COO-* (bonds with "*" and (CH 2 ) a2 bonding). A 2 Indicates oxygen atom or *-COO-(bond with "*" and (CH2 ) a2 bonding). 1 Represents an integer 0 or 1, a 2 represents an integer of 2 to 10. Cy represents 1,4-cyclohexylene or 1,4-phenylene.

[0107] [B]: A diamine having a specific side chain structure represented by the following formula [S2].

[0108] —X 3 —R 2 [S2]

[0109] In the above formula [S2], X 3 Indicates a single bond, -CONH-, -NHCO-, -CON(CH 3 )-, -NH-, -O-, -CH 2 O-, -COO- or -OCO-. In view of the liquid crystal orientation of the liquid crystal aligning agent, X 3 Preferred are -CONH-, -NHCO-, -O-, -CH 2 O-, -COO- or -OCO-.

[0110] In the above formula [S2], R 2 represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms. 2 Any hydrogen in R is optionally substituted by fluorine. 2 An alkyl group having 3 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms is preferred.

[0111] [C]: A diamine having a specific side chain structure represented by the following formula [S3].

[0112] —X 4 —R 3 [S3]

[0113] In the above formula [S3], X 4 Indicates -CONH-, -NHCO-, -O-, -COO- or -OCO-. 3 It represents a structure having a steroid skeleton. The steroid skeleton here has a skeleton represented by the following formula (st) in which three six-membered rings and one five-membered ring are bonded.

[0114]

[0115] As an example of the above formula [S3], the following formula [S3-x] can be mentioned.

[0116]

[0117] In the above formula [S3-x], X represents the above formula [X1] or [X2]. In addition, Col represents at least one selected from the group consisting of the above formulas [Col1] to [Col3], and G represents at least one selected from the group consisting of the above formulas [G1] to [G4]. * represents a site bonded to another group.

[0118] Examples of preferred combinations of X, Col, and G in the formula [S3-x] include the following combinations: [X1], [Col1], and [G1]; [X1], [Col1], and [G2]; [X1], [Col2], and [G1]; [X1], [Col2], and [G2]; [X1], [Col3], and [G2]; [X1], [Col3], and [G1]; [X2], [Col1], and [G2]; [X2], [Col2], and [G2]; [X2], [Col2], and [G1]; [X2], [Col3], and [G2]; [X2], [Col1], and [G1].

[0119] Specific examples of the formula [S3] include a structure obtained by removing a hydroxyl group from a steroid compound described in paragraph

[0024] of Japanese Patent Application Laid-Open No. 4-281427, a structure obtained by removing an acid chloride from a steroid compound described in paragraph

[0030] of the same publication, a structure obtained by removing an amino group from a steroid compound described in paragraph

[0038] of the same publication, a structure obtained by removing a halogen group from a steroid compound described in paragraph

[0042] of the same publication, and structures described in paragraphs

[0018] to

[0022] of Japanese Patent Application Laid-Open No. 8-146421.

[0120] It should be noted that, as a representative example of a steroid skeleton, cholesterol (a combination of [Col1] and [G2] in the above formula [S3-x]) can be cited, but a steroid skeleton that does not contain the cholesterol can also be used. That is, as a diamine having a steroid skeleton, for example, 3,5-diaminobenzoic acid cholesterol ester can be cited, and a diamine component that does not contain a diamine having the cholesterol skeleton can also be used. In addition, as a diamine having a specific side chain structure, a diamine that does not contain an amide at the connecting position of the diamine and the side chain can also be used. Even if such a diamine is used, in the present embodiment, even if a diamine component that does not contain a diamine having a cholesterol skeleton is used, a liquid crystal alignment film and a liquid crystal display element that can ensure a high voltage retention rate even after a long time can be provided.

[0121] In addition, the diamine which has the side chain structure represented by said formula [S1] - [S3] is represented by the structure of following formula [1-S1] - [1-S3], respectively.

[0122]

[0123] In the above formula [1-S1], X 1 , X 2 , G 1 , G 2 , R 1 , m and n are the same as those in the above formula [S1]. In the above formula [1-S2], X 3 and R 2 The same as in the above formula [S2]. In the above formula [1-S3], X 4 and R 3 The same as in the above formula [S3].

[0124] (Diamine having a characteristic side chain structure of two side chains that exhibits vertical alignment)

[0125] The diamine having a characteristic side chain structure of a two-side chain type that exhibits vertical alignment is represented by, for example, the following formula [N1].

[0126]

[0127] In the above formula [N1], X represents a single bond, -O-, -C(CH 3 ) 2 -, -NH-, -CO-, -NHCO-, -COO-, -(CH 2 ) m -、-SO 2 - or a divalent organic group composed of any combination thereof. Among them, X preferably represents a single bond, -O-, -NH-, -O-(CH 2 ) m -O-. Examples of "any combination thereof" include: -O-(CH 2 ) m -O-, -O-C(CH 3 ) 2 -、-CO-(CH 2 ) m -、-NH-(CH 2 ) m -、-SO 2 -(CH 2 ) m -、-CONH-(CH 2 ) m -、-CONH-(CH 2 )m -NHCO-、-COO-(CH 2 ) m -OCO-, etc. m represents an integer of 1-8.

[0128] In the above formula [N1], two Ys each independently represent a structure of the following formula [1-1].

[0129]

[0130] In the above formula [1-1], Y 1 and Y 3 Each independently represents a single bond, -(CH 2 ) a -(a represents an integer of 1 to 15), -O-, -CH 2 O-, -COO- or -OCO-. Y 2 Represents a single bond or -(CH 2 ) b - (b represents an integer from 1 to 15). 1 or Y 3 Represents a single bond or -(CH 2 ) a - In the case of Y 2 Indicates a single bond. In addition, 1 Indicates -O-, -CH 2 O-, -COO- or -OCO-, and / or Y 3 Indicates -O-, -CH 2 In the case of O-, -COO- or -OCO-, Y 2 Represents a single bond or -(CH 2 ) b -

[0131] In addition, in formula [1-1], Y 4 It represents at least one divalent cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocyclic ring, or a divalent organic group having 17 to 51 carbon atoms and having a steroidal skeleton. Any hydrogen atom forming the cyclic group is optionally substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom.

[0132] In the above formula [1-1], Y 5 represents at least one cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocyclic ring. Any hydrogen atom forming the cyclic group is optionally substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom.

[0133] In the above formula [1-1], Y 6 represents at least one selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorinated alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, and a fluorinated alkoxy group having 1 to 18 carbon atoms. n represents an integer of 0 to 4.

[0134] In the above formula [N1], the positions of Y and X may be meta or ortho, preferably ortho. That is, the above formula [N1] is preferably the following formula [1'].

[0135]

[0136] In the above formula [N1], the two amino groups (-NH 2 ) can be any position on the benzene ring, but is preferably a position shown in the following formulas [1]-a1 to [1]-a3, and more preferably the following formula [1]-a1. In the following formula, X is the same as in the above formula [N1]. It should be noted that the following formulas [1]-a1 to [1]-a3 illustrate the positions of the two amino groups, and the symbol of Y represented in the above formula [N1] is omitted.

[0137]

[0138] Therefore, based on the above formulas [1′] and [1]-a1 to [1]-a3, the above formula [N1] is preferably any structure selected from the group consisting of the following formulas [1]-a1-1 to [1]-a3-2, and more preferably a structure represented by the following formula [1]-a1-1. In the following formulas, X and Y are the same as in the case of formula [N1].

[0139]

[0140] In addition, examples of the above formula [1-1] include the following formulas [1-1]-1 to [1-1]-22. Among them, as examples of the above formula [1-1], the following formulas [1-1]-1 to [1-1]-4, [1-1]-8, or [1-1]-10 are preferred. In the following formulas, * represents the bonding position to the phenyl group in the above formulas [1], [1'], and [1]-a1 to [1]-a3.

[0141]

[0142]

[0143] The diamine component contains two side chain diamines having a predetermined structure, thereby forming a liquid crystal alignment film whose ability to orient the liquid crystal vertically is not easily reduced even when exposed to excessive heating. In addition, the diamine component contains the two side chain diamines, thereby forming a liquid crystal alignment film whose ability to orient the liquid crystal vertically is not easily reduced even when the film is damaged by contact with certain foreign matter. That is, the diamine component contains the two side chain diamines, thereby providing a liquid crystal alignment agent that can obtain a liquid crystal alignment film with various excellent characteristics.

[0144] Moreover, as another diamine, the diamine represented by the following general formula (Y) is mentioned secondly.

[0145]

[0146] In the above formula (Y), A 1 and A 2 Each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. 1 and A 2 Preferably, a hydrogen atom or a methyl group is used. 1 The structures are as shown in the following formulas (Y-1) to (Y-68).

[0147]

[0148]

[0149]

[0150] (Boc in the formula represents tert-butoxycarbonyl. * represents a bonding bond.)

[0151] In addition, as other diamines, the third is a diamine having a thiophene or furan structure described in International Publication No. WO2018 / 092759, preferably a diamine having a structure represented by the following formula (sf); 2,3-diaminopyridine; 2,6-diaminopyridine; 3,4-diaminopyridine; 2,4-diaminopyrimidine; diaminoorganosiloxanes such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; aliphatic diamines such as m-xylene diamine; alicyclic diamines such as 4,4-methylenebis(cyclohexylamine), etc.

[0152]

[0153] (Y 1 represents a sulfur atom or an oxygen atom, R 2 Each independently represents a single bond or a group "*1-R 5 -Ph-*2”,R 5represents a single bond, -O-, -COO-, -OCO-, -(CH 2 ) l -、-O(CH 2 ) m A divalent organic group in the group consisting of O-, -CONH- and -NHCO- (l, m represent integers of 1 to 5, *1 represents a site bonded to the benzene ring in the formula (pn), and *2 represents a site bonded to the amino group in the formula (pn). Ph represents a phenylene group. n represents 1 to 3)

[0154] The other diamines may be used alone or in combination of two or more.

[0155] (Tetracarboxylic acid component)

[0156] As the tetracarboxylic acid component for obtaining the specific polymer, tetracarboxylic dianhydride or a derivative thereof (tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester or tetracarboxylic acid dialkyl ester dihalide) represented by the following formula [4] (these are collectively referred to as specific tetracarboxylic acid) can be used.

[0157]

[0158] (In formula [4], Z 1 represents at least one structure selected from the group consisting of the following formula [4a] to formula [4q].

[0159]

[0160]

[0161] In formula [4a], Z 1 ~Z 4 Z each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring. 5 and Z 6 Each independently represents a hydrogen atom or a methyl group.

[0162] Z in formula [4] 1 Among them, tetracarboxylic dianhydrides and tetracarboxylic acid derivatives thereof having structures represented by formula [4a], formula [4c] to formula [4g], formula [4k] to formula [4m] or formula [4p] are preferred from the perspective of ease of synthesis and ease of polymerization reactivity when producing a polymer. Tetracarboxylic dianhydrides and tetracarboxylic acid derivatives thereof having structures represented by formula [4a], formula [4e] to formula [4g], formula [4l], formula [4m] or formula [4p] are more preferred. Tetracarboxylic dianhydrides and tetracarboxylic acid derivatives thereof having structures represented by formula [4a], formula [4e], formula [4f], formula [4l], formula [4m] or formula [4p] are particularly preferred.

[0163] More specifically, it is preferable to use the following formula [4a-1] or formula [4a-2].

[0164]

[0165] The specific tetracarboxylic acid is preferably 50 to 100 mol% in 100 mol% of all tetracarboxylic acid components. Among them, it is preferably 70 to 100 mol%, and more preferably 80 to 100 mol%.

[0166] The specific tetracarboxylic acid may be used alone or in combination of two or more depending on the solubility of the specific polymer in the solvent, the coating property of the liquid crystal aligning agent, the alignment of the liquid crystal when the liquid crystal aligning film is formed, the voltage holding ratio, the stored charge and other properties.

[0167] As a tetracarboxylic acid component for obtaining a specific polymer, you may contain tetracarboxylic acids other than the above-mentioned specific tetracarboxylic acids (hereinafter, also referred to as other tetracarboxylic acids).

[0168] As other tetracarboxylic acids, the tetracarboxylic acid compounds, tetracarboxylic dianhydrides, tetracarboxylic acid dihalide compounds, tetracarboxylic acid dialkyl ester compounds, or tetracarboxylic acid dialkyl ester dihalide compounds shown below can be mentioned.

[0169] That is, other tetracarboxylic acids include 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4-biphenyltetracarboxylic acid, bis(3,4-dicarboxyphenyl)ether, 3,3',4,4'-benzophenonetetracarboxylic acid, bis(3,4-dicarboxyphenyl)sulfone, bis(3,4-dicarboxyphenyl)methane, 2,2-bis(3,4-dicarboxyphenyl) Propane, 1,1,1,3,3,3-hexafluoro-2,2-bis(3,4-dicarboxyphenyl)propane, bis(3,4-dicarboxyphenyl)dimethylsilane, bis(3,4-dicarboxyphenyl)diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis(3,4-dicarboxyphenyl)pyridine, 3,3',4,4'-diphenylsulfonetetracarboxylic acid, 3,4,9,10-perylenetetracarboxylic acid or 1,3-diphenyl-1,2,3,4-cyclobutanetetracarboxylic acid, etc.

[0170] Other tetracarboxylic acids can be used alone or in combination of two or more depending on the solubility of the specific polymer in the solvent, the coating properties of the liquid crystal aligning agent, the liquid crystal alignment when formed into a liquid crystal aligning film, the voltage holding ratio, the stored charge and other properties.

[0171] <Method for producing specific polymer>

[0172] The specific polymer is at least one selected from the group consisting of a polyimide precursor obtained by polymerizing a diamine component and a tetracarboxylic acid component, and a polyimide obtained by imidating the polyimide precursor.

[0173] The reaction of the diamine component and the tetracarboxylic acid component is usually carried out in a solvent. The solvent used at this time is not particularly limited as long as it dissolves the generated polyimide precursor. Specific examples of the solvent used in the reaction are listed below, but are not limited to these examples.

[0174] For example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropaneamide, 3-butoxy-N,N-dimethylpropaneamide, dimethyl sulfoxide, or 1,3-dimethyl-imidazolidinone can be mentioned. In addition, when the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, etc. can be used.

[0175] These solvents can be used alone or in combination. Moreover, even if it is a solvent that does not dissolve the polyimide precursor, it can be mixed with the solvent in the range that the generated polyimide precursor does not precipitate. In addition, the moisture in the solvent hinders the polymerization reaction, and then becomes the reason for hydrolyzing the generated polyimide precursor, so the solvent is preferably a dehydrated solvent.

[0176] When the diamine component and the tetracarboxylic acid component are reacted in a solvent, the following methods can be cited: a method of stirring a solution obtained by dispersing or dissolving the diamine component in a solvent, directly adding the tetracarboxylic acid component, or a method of dispersing or dissolving the tetracarboxylic acid component in a solvent to add the diamine component; on the contrary, a method of adding the diamine component to a solution obtained by dispersing or dissolving the tetracarboxylic acid component in a solvent, a method of alternately adding the diamine component and the tetracarboxylic acid component to the reaction system, etc., any of which can be used. In addition, when a plurality of diamine components or tetracarboxylic acid components are used and reacted, they can be reacted in a premixed state, or they can be reacted separately in sequence, or low molecular weight substances reacted separately can be mixed and reacted to form a polymer.

[0177] The temperature for polycondensing the diamine component and the tetracarboxylic acid component can be selected from any temperature of -20 to 150 ° C, preferably in the range of -5 to 100 ° C. The reaction can be carried out at any concentration, but if the concentration is too low, it becomes difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and it is difficult to stir uniformly. Therefore, the concentration of the polymer is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction is carried out at a high concentration in the early stage, and a solvent can be added thereafter.

[0178] In the polymerization reaction to obtain the polyimide precursor, the total molar ratio of the tetracarboxylic acid component to the total molar ratio of the diamine component is preferably 0.8 to 1.2. As in a normal polycondensation reaction, the closer this molar ratio is to 1.0, the greater the molecular weight of the generated polyimide precursor.

[0179] The imidized polymer is a polyimide obtained by ring-closing a polyimide precursor. In the polyimide, the ring-closure rate (also called imidization rate) of the amic acid group (amide acid group) does not necessarily need to be 100% and can be arbitrarily adjusted according to the application and purpose.

[0180] As a method of imidating a polyimide precursor, thermal imidation which heats the solution of a polyimide precursor as it is, and catalyst imidation which adds a catalyst to the solution of a polyimide precursor are mentioned.

[0181] The temperature when the polyimide precursor is thermally imidized in a solution is preferably 100 to 400° C., more preferably 120 to 250° C., and a method in which the imidization reaction is carried out while removing water generated by the imidization reaction to the outside of the system is preferred. Catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring at −20 to 250° C., preferably 0 to 180° C.

[0182] The amount of the basic catalyst is preferably 0.5 to 30 times, more preferably 2 to 20 times, the amount of the amic acid group. The amount of the acid anhydride is preferably 1 to 50 times, more preferably 3 to 30 times, the amount of the amic acid group.

[0183] Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. Among them, pyridine is preferred because it has a moderate basicity that allows the reaction to proceed.

[0184] Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. In particular, acetic anhydride is preferred because purification after the reaction is easy. The imidization rate obtained by catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

[0185] The imidization rate of the polyimide precursor or the imidized polymer thereof of the present invention is preferably 1 to 95%, more preferably 20% to 80%, further preferably 40% to 70%.

[0186] When the polyimide precursor or its imidized polymer generated by the reaction solution is recovered, the reaction solution is added to the solvent to precipitate it. As the solvent for precipitation, methanol, ethanol, isopropanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, water, etc. are listed. After the polymer precipitated by the solvent is filtered and recovered, it can be dried at normal pressure or reduced pressure, at room temperature or by heating. In addition, if the operation of dissolving the precipitated polymer recovered in the solvent again and reprecipitating and recovering is repeated 2 to 10 times, the impurities in the polymer can be reduced. As the solvent at this time, for example, alcohols, ketones, hydrocarbons, etc. are listed. If three or more solvents selected from them are used, the efficiency of purification is further increased, so it is preferred.

[0187] In the present invention, when the polyimide precursor is a polyamic acid alkyl ester, examples of a specific method for producing the polyimide precursor include the method described in paragraphs

[0054] to

[0062] of International Publication No. WO2011-115077.

[0188] <Liquid crystal alignment agent>

[0189] It is preferable that content of the specific polymer in the liquid crystal aligning agent of this invention is 2-10 mass % in a liquid crystal aligning agent, and, as for content of the specific polymer in the liquid crystal aligning agent of this invention, it is more preferable that it is 3-8 mass %.

[0190] The liquid crystal aligning agent of the present invention may also contain other polymers other than the specific polymer. As polymers other than the specific polymer, cellulose polymers, acrylic polymers, methacrylic polymers, polystyrene, polyamide, polysiloxane, etc. may also be listed. The content of other polymers other than the specific polymer is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass relative to 100 parts by mass of the specific polymer.

[0191] Moreover, although a liquid crystal aligning agent generally contains an organic solvent, content of the organic solvent is preferably 70-99.9 mass % with respect to the liquid crystal aligning agent. This content can be appropriately changed according to the coating method of the liquid crystal aligning agent and the film thickness of the target liquid crystal aligning film.

[0192] The organic solvent used in the liquid crystal alignment agent is preferably a solvent (also referred to as a good solvent) that dissolves a specific polymer. For example, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N,N-dimethylpropaneamide, 3-butoxy-N,N-dimethylpropaneamide, etc. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropaneamide, 3-butoxy-N,N-dimethylpropaneamide or γ-butyrolactone is preferably used.

[0193] The good solvent in the liquid crystal aligning agent of the present invention is preferably 20 to 99% by mass of the whole solvent contained in the liquid crystal aligning agent, more preferably 20 to 90% by mass, particularly preferably 30 to 80% by mass.

[0194] The liquid crystal aligning agent of the present invention can use a solvent (also referred to as a poor solvent) that improves the coating properties and surface smoothness of the liquid crystal aligning film when the liquid crystal aligning agent is applied. Specific examples thereof are given below.

[0195] For example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2- (2-Butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isopentyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), and the like.

[0196] Among them, preferred combinations of solvents include: N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether; N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diisopropyl ether. Ethylene glycol diethyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone; N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisopropyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanol; N-methyl-2-pyrrolidone, γ-butyrolactone and dipropylene glycol dimethyl ether; etc. These poor solvents are preferably 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass. The type and content of such solvents can be appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

[0197] The liquid crystal alignment agent of the present invention may also contain: a dielectric for the purpose of changing the electrical properties of the liquid crystal alignment film, such as the dielectric constant and conductivity; a silane coupling agent for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate; a cross-linking compound for the purpose of improving the hardness and density of the film when the liquid crystal alignment film is made; and an imidization accelerator for the purpose of efficiently carrying out the imidization by heating the polyimide precursor when the coating film is fired.

[0198] Examples of compounds for improving the adhesion between the liquid crystal alignment film and the substrate include compounds containing functional silanes and compounds containing epoxy groups, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-( 2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxy Silyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyl trimethoxysilane, N-benzyl-3-aminopropyl triethoxysilane, N-phenyl-3-aminopropyl trimethoxysilane, N-phenyl-3-aminopropyl triethoxysilane, N-bis(oxyethylene)-3-aminopropyl trimethoxysilane, N-bis(oxyethylene)-3-aminopropyl triethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, Propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N,N',N'-tetraglycidyl-m-xylene diamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, or N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, etc.

[0199] Moreover, in order to improve the mechanical strength of a liquid crystal aligning film, you may add the following additives (CL-1) - (CL-15) to the liquid crystal aligning agent of this invention.

[0200]

[0201] It is preferable that it is 0.1-30 mass parts with respect to 100 mass parts of the polymer components which the said additive contains in a liquid crystal aligning agent.

[0202] <Method for producing liquid crystal alignment film>

[0203] The liquid crystal alignment film is obtained by coating the above-mentioned liquid crystal alignment agent on a substrate to form a coating, preferably drying it, and then firing it. As a substrate, a substrate with high transparency is preferred, and as its material, ceramics such as glass and silicon nitride; plastics such as acrylic and polycarbonate, etc. can be used. As a substrate, from the perspective of simplifying the process, it is preferred to use a substrate formed with an ITO (Indium Tin Oxide: indium tin oxide) electrode for driving liquid crystal. In addition, in a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used as a substrate on one side, and its electrode can also use a light-reflecting material such as aluminum.

[0204] Industrially, screen printing, offset printing, flexographic printing, inkjet printing, etc. can be used to form a coating on a substrate using a liquid crystal aligning agent. In addition, dipping, roll coating, slit coating, spin coating, spray coating, etc. can also be used depending on the purpose.

[0205] After a film of the liquid crystal alignment agent is formed on the substrate, the film is preferably dried by a heating unit such as a heating plate, a heat circulation oven, an IR (infrared) oven, etc., preferably at 30 to 120° C., more preferably at 50 to 120° C., for 1 minute to 10 minutes, more preferably 1 minute to 5 minutes, to evaporate the solvent.

[0206] When the imide precursor in the polymer is thermally imidized, the coating obtained from the liquid crystal aligning agent is then subjected to a calcination treatment by the same heating unit as the above-mentioned drying treatment, preferably at 120 to 250° C., more preferably at 150 to 230° C. The calcination treatment time varies depending on the calcination temperature, but is preferably 5 minutes to 1 hour, and more preferably 5 minutes to 40 minutes.

[0207] The thickness of the coating after the calcination treatment is not particularly limited. If it is too thin, the reliability of the liquid crystal display element may decrease, and if it is too thick, the resistance of the obtained liquid crystal alignment film may increase. Therefore, it is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

[0208] After the calcination treatment, the obtained coating is subjected to an orientation treatment. Examples of the orientation treatment method include a brushing treatment method and a photo-orientation treatment method.

[0209] As a specific example of photo-alignment treatment, radiation biased in a certain direction is irradiated to the surface of the coating. As radiation, ultraviolet rays or visible light with a wavelength of 100 to 800 nm can be used. Among them, ultraviolet rays with a wavelength of 100 to 400 nm are preferred, and ultraviolet rays with a wavelength of 200 to 400 nm are more preferred. In order to improve the orientation of the liquid crystal, the substrate coated with the liquid crystal alignment film can be heated at 50 to 250°C while irradiating it with ultraviolet rays. In addition, the irradiation amount of the radiation is preferably 1 to 10000 mJ / cm 2 Among them, 100 to 5000 mJ / cm 2 The liquid crystal alignment film produced in this way can stably align the liquid crystal molecules in a certain direction.

[0210] The higher the extinction ratio of polarized ultraviolet light, the higher the anisotropy can be imparted, which is preferred. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10:1 or more, and more preferably 20:1 or more.

[0211] The coating film subjected to the alignment treatment may be further subjected to at least one treatment selected from the group consisting of a heat treatment and a contact treatment with a solvent.

[0212] The heat treatment after the alignment treatment can be performed by the same heating means as the drying treatment and the calcining treatment, preferably at 180 to 250° C., more preferably at 180 to 230° C. When the temperature of the heat treatment is within the above range, the contrast of the liquid crystal display element obtained by the obtained liquid crystal alignment film can be improved.

[0213] The time of the heat treatment varies depending on the heating temperature, but is preferably 5 minutes to 1 hour, more preferably 5 to 40 minutes.

[0214] The solvent used for the contact treatment with the solvent is not particularly limited as long as it is a solvent that dissolves impurities and the like adhering to the liquid crystal alignment film.

[0215] Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate, etc. Among them, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate are preferred from the perspective of versatility and safety of the solvent. Water, 1-methoxy-2-propanol or ethyl lactate is more preferred. These solvents may be one or more.

[0216] As the above-mentioned contact treatment, there can be cited: immersion treatment, spray treatment (also referred to as spray treatment). The treatment time in these treatments is preferably 10 seconds to 1 hour, and in particular, a scheme of immersion treatment for 1 to 30 minutes can be cited. In addition, the temperature during the contact treatment can be room temperature or heated, preferably 10 to 80°C, and 20 to 50°C can be cited. During the contact treatment, ultrasonic treatment or the like can also be performed as needed.

[0217] After the contact treatment, rinsing (also referred to as leaching) and drying may be performed using a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone. At this time, either leaching or drying may be performed, or both may be performed. The drying temperature is preferably 50 to 150° C., and 80 to 120° C. may be cited. In addition, the drying time is preferably 10 seconds to 30 minutes, and preferably 1 to 10 minutes.

[0218] After the contact treatment with the solvent, the heat treatment after the alignment treatment may be performed. By adopting such a configuration, a liquid crystal alignment film having excellent liquid crystal orientation can be obtained.

[0219] <Liquid crystal display device>

[0220] The liquid crystal alignment film of the present invention can be applied to various driving modes such as TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, IPS (In-Plane Switching) mode, FFS (Fringe Field Switching) mode, VA (Vertical Alignment) mode, MVA (Multi-domain Vertical Alignment) mode, PSA (Polymer Sustained Alignment) mode, etc. It is preferably used as a liquid crystal alignment film for liquid crystal display elements of transverse electric field modes such as IPS mode and FFS mode, and is particularly useful as a liquid crystal display element of FFS mode. The liquid crystal display element of the present invention is an element made by preparing a liquid crystal box (cell) by a known method after obtaining a substrate with a liquid crystal alignment film from the above-mentioned liquid crystal alignment agent, and using the liquid crystal box.

[0221] As an example of a method for manufacturing a liquid crystal cell, a passive matrix liquid crystal display element is used as an example. It should be noted that an active matrix liquid crystal display element in which a conversion element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting an image display may also be used.

[0222] Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be, for example, ITO electrodes, and are patterned in a manner that enables the desired image display. Next, an insulating film is provided on each substrate in a manner that covers the common electrode and the segment electrode. The insulating film can be, for example, a SiO2 film formed by a sol-gel method. 2 -TiO 2 Then, under the above conditions, a liquid crystal alignment film is formed on each substrate, and the substrate on one side is overlapped with the substrate on the other side in a manner that the liquid crystal alignment film faces each other, and the periphery is bonded with a sealant. In order to control the gap between the substrates, it is usually preferred to mix spacers into the sealant. In addition, it is preferred to also spread spacers for controlling the gap between the substrates in the in-plane portion where the sealant is not provided. In a portion of the sealant, an opening portion that can be filled with liquid crystal from the outside is pre-set.

[0223] Then, through the opening provided in the sealant, the liquid crystal material is injected into the space surrounded by the two substrates and the sealant. Then, the opening is sealed with an adhesive. As for injection, the following methods can be cited: vacuum injection method, method using capillary phenomenon in the atmosphere, and ODF (One Drop Fill: liquid crystal dripping) method can also be used. As the liquid crystal material, any one of positive and negative dielectric anisotropy can also be used. In the present invention, from the viewpoint of liquid crystal orientation, the liquid crystal with negative dielectric anisotropy is preferred, which can be used according to the purpose.

[0224] After the liquid crystal material is injected into the liquid crystal cell, the polarizing plate is placed. Specifically, it is preferable to bond a pair of polarizing plates to the surfaces of the two substrates on the opposite sides to the liquid crystal layer.

[0225] [Example]

[0226] The present invention will be described in further detail below with reference to Examples, but the present invention is not limited to the contents explained here. The abbreviations of the compounds used are as follows.

[0227] (Diamine component)

[0228]

[0229] NMP: N-methyl-2-pyrrolidone.

[0230] BCS: ethylene glycol monobutyl ether.

[0231] <Determination of Molecular Weight of Polyimide>

[0232] The molecular weight of the polyimide was measured as follows using a room temperature gel permeation chromatography (GPC) apparatus (SSC-7200) manufactured by Senshu Scientific Co., Ltd. and a column (KD-803, KD-805) manufactured by Shodex Corporation.

[0233] Column temperature: 50°C.

[0234] Eluent: N, N'-dimethylformamide (as an additive, lithium bromide-water (LiBr·H 2 O) is 30mmol / L, phosphoric acid / anhydrous crystals (o-phosphoric acid) is 30mmol / L, and tetrahydrofuran (THF) is 10ml / L).

[0235] Flow rate: 1.0 ml / min.

[0236] Standard samples for preparing the calibration curve: TSK standard polyethylene oxide manufactured by Tosoh Corporation (molecular weight of about 9,000,000, 150,000, 100,000, and 30,000) and polyethylene glycol manufactured by Polymer Laboratory (molecular weight of about 12,000, 4,000, and 1,000).

[0237] <Measurement of Imidization Ratio>

[0238] 20 mg of polyimide powder was added to an NMR sample tube (NMR standard sample tube φ5 manufactured by Kusano Scientific Co., Ltd.), and deuterated dimethyl sulfoxide (DMSO-d 6 , 0.05% TMS mixture) 0.53 ml, apply ultrasound to completely dissolve it.

[0239] The solution was measured for 500 MHz proton NMR using an NMR measuring instrument (JNW-ECA500) manufactured by DATUM Co., Ltd. of Japan Electronics Co., Ltd. The imidization rate was determined as follows: a proton derived from a structure that does not change before and after imidization was determined as a reference proton, and the peak integral value of the proton derived from the NH group of the amic acid appearing around 9.5 to 10.0 ppm was used to determine the rate using the following calculation formula.

[0240] Imidization rate (%) = (1-α·x / y) × 100

[0241] <Synthesis of polyimide polymer>

[0242] <Synthesis example 1>

[0243] D1 (9.14 g), DA-1 (4.68 g, a molar ratio of 0.3 to all diamine components), DA-2 (3.25 g, a molar ratio of 0.4 to all diamine components), DA-3 (1.95 g, a molar ratio of 0.2 to all diamine components), and DA-4 (1.02 g, a molar ratio of 0.1 to all diamine components) were mixed in an NMP solvent (80.17 g), and reacted at 60° C. for 12 hours to obtain a polyamic acid solution.

[0244] NMP (103.85 g) was added to the polyamic acid solution (50.0 g), diluted to 6.5% by mass, and then acetic anhydride (20.84 g) and pyridine (3.23 g) were added as imidization catalysts, and the mixture was reacted at 80° C. for 5 hours. The reaction solution was put into methanol (622.70 g), and the obtained precipitate was filtered out. The precipitate was washed with methanol, and dried under reduced pressure at 60° C. to obtain a polyimide powder (A). The imidization rate of the polyimide was 72%, Mn was 11800, and Mw was 41800.

[0245] <Synthesis Examples 2 to 4, Comparative Synthesis Examples 1 and 2>

[0246] In Synthesis Example 1, except that the materials and proportions were changed as shown in Tables 1 and 2, the same procedure as in Synthesis Example 1 was carried out to obtain polyimide powders (B to D) of Synthesis Examples 2 to 4 and polyimide powders (E and F) of Comparative Synthesis Examples 1 and 2.

[0247] <Synthesis example 5>

[0248] D2 (5.12 g), DA-7 (3.26 g, 0.4 molar ratio relative to all diamine components), DA-8 (3.97 g, 0.4 molar ratio relative to all diamine components), DA-9 (3.24 g, 0.2 molar ratio relative to all diamine components) were mixed in NMP solvent (62.43 g), reacted at 60°C for 3 hours, cooled to room temperature, D3 (3.86 g) and NMP solvent (15.44 g) were added, and reacted at 40°C for 12 hours to obtain a polyamic acid solution (G). The polyamic acid solution (G) had an Mn of 10,600 and an Mw of 35,700.

[0249] [Table 1]

[0250]

[0251] In Table 1, the right side in the parentheses after the names of the diamine components shows the molar ratio of each diamine used for the reaction relative to the total diamine components.

[0252] [Table 2]

[0253] Synthesis example Polyimide powder Acetic anhydride Pyridine Methanol Imidization rate Number average molecular weight Weight average molecular weight Synthesis example 1 A 20.84g 3.23g 622.70g 69％ 11,800 41,800 Synthesis example 2 B 20.42g 3.17g 621.00g 73％ 10,800 38,400 Synthesis example 3 C 19.87g 3.08g 618.79g 71％ 11,600 34,500 Synthesis example 4 D 19.60g 3.04g 617.68g 74％ 12,100 46,600 Comparative Synthesis Example 1 E 21.39g 3.32g 624.97g 65％ 11,300 40,700 Comparative Synthesis Example 2 F 21.18g 3.28g 624.07g 72％ 10,900 31,200

[0254] <Example 1>

[0255] NMP (44.0 g) was added to the polyimide powder (A) (6.0 g) obtained in Synthesis Example 1, and the mixture was stirred at 70° C. for 40 hours to dissolve the mixture. BCS (50.0 g) was added to the solution, and the mixture was stirred for 5 hours to obtain a liquid crystal aligning agent [1] of Example 1. No abnormalities such as turbidity and precipitation were observed in the liquid crystal aligning agent, and it was confirmed that the resin component was uniformly dissolved.

[0256] <Examples 2 to 4, Comparative Examples 1 and 2>

[0257] In Example 1, except that the polyimide material was changed as shown in Table 3, liquid crystal aligning agents [2] to [4] of Examples 2 to 4 and liquid crystal aligning agents [5] and [6] of Comparative Examples 1 and 2 were obtained in the same manner as in Example 1. No abnormalities such as turbidity and precipitation were observed in these liquid crystal aligning agents, and it was confirmed that the resin component was uniformly dissolved.

[0258] <Example 5>

[0259] NMP (29.0 g) was added to the polyamic acid solution (G) (21.0 g) obtained in Synthesis Example 5, and the mixture was stirred for 30 minutes. BCS (35.0 g) was added and stirred for further 30 minutes, and then a liquid crystal aligning agent [1] (30.0 g) was added and stirred for 5 hours to obtain a liquid crystal aligning agent [7] of Example 5. No abnormalities such as turbidity and precipitation were observed in the liquid crystal aligning agent, and it was confirmed that the resin component was uniformly dissolved.

[0260] <Production of Liquid Crystal Cell>

[0261] The liquid crystal alignment agents of Examples 1 to 5 and Comparative Examples 1 and 2 were spin-coated on the ITO surface of a glass substrate with ITO (30 mm in length, 40 mm in width, and 0.7 mm in thickness) cleaned with pure water and IPA (isopropyl alcohol), and fired on a hot plate at 70°C for 90 seconds, and then heated in an infrared heating furnace at 230°C for 20 minutes to produce a polyimide-coated substrate with a film thickness of 100 nm.

[0262] Two polyimide-coated substrates were prepared by the above method. After 4 μm bead-shaped spacers were scattered on the liquid crystal alignment film surface of one substrate, a thermosetting sealing material (XN-1500T manufactured by Kyoritsu Chemical Co., Ltd.) was printed on it. Next, the surface of the other substrate on which the liquid crystal alignment film was formed was set as the inner side, and it was bonded to the previous substrate, and the sealing material was cured to produce an empty box. Liquid crystal MLC-3023 (trade name manufactured by MERCK Co., Ltd.) containing a polymerizable compound for PSA was injected into the empty box by the reduced pressure injection method to produce a liquid crystal box. The voltage holding ratio of the liquid crystal box was measured.

[0263] Next, while a DC voltage of 15 V was applied to the liquid crystal cell, 10 J / cm 2 UV (also referred to as primary PSA treatment) passed through a 325 nm cutoff filter. The UV illuminance was measured using UV-MO3A manufactured by ORC Corporation.

[0264] Then, in order to deactivate the unreacted polymerizable compound remaining in the liquid crystal cell, UV irradiation was performed for 30 minutes using a UV-FL irradiation device manufactured by Toshiba Lighting & Technology (UV lamp: FLR40SUV32 / A-1) without applying voltage (referred to as secondary PSA treatment). Then, the voltage holding ratio was measured.

[0265] <Evaluation of voltage holding ratio>

[0266] Using the liquid crystal cell prepared above, a voltage of 1 V was applied for 60 μs in a hot air circulation oven at 60° C., and the voltage was measured 1667 msec later. The voltage holding ratio was calculated as the voltage holding ratio. The voltage holding ratio was measured using VHR-1 manufactured by TOYO Corporation.

[0267] <Evaluation of high temperature and high humidity resistance>

[0268] The liquid crystal cell prepared above was left to stand for 7 days in a thermo-hygrostat (PR-2KP manufactured by ESPEC) at 85°C and 85% humidity, and then the voltage holding ratio was measured. The difference between the voltage holding ratio measured here and the voltage holding ratio after the secondary PSA treatment was taken as the VHR variation.

[0269] [Table 3]

[0270]

[0271] As shown in Table 3, the VHR after the secondary PSA treatment was less than 86% in Comparative Examples 1 and 2, but was 86% or more in Examples 1 to 5. Furthermore, it was confirmed that in Comparative Examples 1 and 2, the VHR change amount was a large change of 65% or more by placing the liquid crystal cell under high temperature and high humidity, while in Examples 1 to 5, the VHR change amount could be reduced to a small change amount of 50% or less.

[0272] <Fabrication of a liquid crystal cell for evaluating the tilt angle>

[0273] The liquid crystal alignment agents of Examples 1 to 5 and Comparative Examples 1 and 2 were spin-coated on the ITO surface of a 3.5×3mm ITO electrode substrate (35mm in length, 30mm in width, 0.5mm in thickness) with an ITO electrode pattern having a pixel size of 200μm×600μm and a line width / line spacing of 3μm, respectively, which had been washed with pure water and IPA (isopropyl alcohol); and a glass substrate (35mm in length, 30mm in width, 0.7mm in thickness) with an ITO electrode patterned with a spacer (photo spacer) of 3.2μm in height. Then, after sintering at 70°C for 90 seconds on a hot plate, sintering was performed in an infrared heating furnace at 230°C for 20 minutes or 60 minutes to produce a polyimide-coated substrate with a film thickness of 100nm.

[0274] The ITO electrode substrate on which the ITO electrode pattern is formed is divided into four cross checker (grid) patterns, and can be driven separately for each of the four regions.

[0275] Two polyimide-coated substrates were prepared by the above method, and a thermosetting sealing material (XN-1500T manufactured by Kyoritsu Chemical Co., Ltd.) was printed from above. Next, the surface of the other substrate on which the liquid crystal alignment film was formed was set as the inner side, and after being bonded to the previous substrate, the sealing material was cured to produce an empty box. Liquid crystal MLC-3023 (trade name manufactured by MERCK Co., Ltd.) containing a polymerizable compound for PSA was injected into the empty box by the reduced pressure injection method to produce a liquid crystal box. The voltage holding ratio of the liquid crystal box was measured.

[0276] Next, while a DC voltage of 15 V was applied to the liquid crystal cell, 10 J / cm 2 UV that has passed through a 325 nm cutoff filter (also referred to as primary PSA treatment). The UV illuminance was measured using UV-MO3A manufactured by ORC Corporation.

[0277] Then, in order to deactivate the unreacted polymerizable compound remaining in the liquid crystal cell, UV irradiation was performed for 30 minutes using a UV-FL irradiation device manufactured by Toshiba Lighting & Technology (UV lamp: FLR40SUV32 / A-1) without applying voltage (referred to as secondary PSA treatment). Then, the pretilt angle was measured.

[0278] <Evaluation of pretilt angle>

[0279] The pretilt angle of the pretilt angle evaluation liquid crystal box prepared above was measured using an LCD analyzer (LCA-LUV42A manufactured by Mingling Technica). The difference in pretilt angle was obtained by subtracting the pretilt angle obtained by using a polyimide coated substrate sintered in an infrared heating furnace at 230°C for 20 minutes from the pretilt angle obtained by using a polyimide coated substrate sintered for 60 minutes. The evaluation results are shown in Table 4.

[0280] [Table 4]

[0281]

[0282] As shown in Table 4, it was confirmed that in Comparative Example 1 in which the siloxane skeleton was not introduced, the difference in the pretilt angle was 2.0°, and in Examples 1 to 5, the difference in the pretilt angle could be set to 0.4° or less.

[0283] <Evaluation of solubility>

[0284] BCS was added dropwise to 10 g of the liquid crystal aligning agents of Examples 1 to 5 and Comparative Examples 1 and 2 while stirring, and the solubility was calculated from the weight of the white turbidity by the following formula.

[0285] Solubility (%) = (amount of BCS in the liquid crystal alignment agent + amount of BCS added dropwise) / (amount of liquid crystal alignment agent + amount of BCS added dropwise) × 100

[0286] <Preparation of seal adhesion measurement substrate>

[0287] The liquid crystal alignment agents of Examples 1 to 5 and Comparative Examples 1 and 2 were spin-coated on the ITO surface of a glass substrate with ITO (30 mm in length, 40 mm in width, and 0.7 mm in thickness) cleaned with pure water and IPA (isopropyl alcohol), fired on a hot plate at 70°C for 90 seconds, and then fired in an infrared heating furnace at 230°C for 20 minutes to produce a polyimide-coated substrate with a film thickness of 100 nm.

[0288] Two polyimide-coated substrates were prepared by the above method. After 4 μm bead-shaped spacers were applied on the liquid crystal alignment film surface of one substrate, a sealant (XN-1500T manufactured by Kyoritsu Chemical Co., Ltd.) was dripped. Next, the liquid crystal alignment film surface of the other substrate was set to the inner side, and the substrates were bonded in such a way that the overlapping width of the substrates was 1 cm and the diameter of the sealant was close to 3 mm in a circular shape. After the two bonded polyimide-coated substrates were fixed, they were calcined in a hot air circulation oven at 150°C for 1 hour to prepare a sample for adhesion evaluation.

[0289] <Evaluation of sealing tightness>

[0290] The above-mentioned sample for evaluation of adhesion was fixed to the lower part of the three-point bending fixture (interval 64cm) of the desktop precision universal testing machine (manufactured by Shimadzu Corporation, AGS-X500N) with the substrate for evaluation of adhesion, and then pressed from the upper part of the center of the substrate at a speed of 5mm / min to measure the force (N) during peeling. The value of the force (N) during peeling measured in the above method divided by the diameter of the sealant was evaluated as the sealing adhesion. The sealing evaluation results are shown in Table 5.

[0291] [Table 5]

[0292] Example Liquid crystal alignment agent Polyimide powder Solubility Sealing tightness (N / mm) Example 1 Liquid crystal alignment agent[1] A 74％ 2.7 Example 2 Liquid crystal alignment agent[2] B 82％ 3.5 Example 3 Liquid crystal alignment agent[3] C 78％ 2.6 Example 4 Liquid crystal alignment agent[4] D 62％ 3.5 Example 5 Liquid crystal alignment agent[7] G 74％ 4.2 Comparative Example 1 Liquid crystal alignment agent[5] E 52％ 1.7 Comparative Example 2 Liquid crystal alignment agent[6] F 57％ 1.6

[0293] As shown in Table 5, it was confirmed that the solubility was less than 60% in Comparative Examples 1 and 2, but 60% or more in Examples 1 to 5. The sealing adhesion was also confirmed to be less than 2 N / mm in Comparative Examples 1 and 2, but 2.5 N / mm or more in Examples 1 to 5.

[0294] It should be noted that all the contents of the specification, claims, and abstract of Japanese Patent Application No. 2019-021819 filed on February 8, 2019 are cited herein and introduced as a disclosure of the specification of the present invention.

Claims

1. A liquid crystal alignment agent, characterized in that: The invention relates to a method for preparing a polyimide having a prepolymer and a polyimide obtained by imidizing the polyimide precursor, wherein the prepolymer and the polyimide are obtained by polymerizing the diamine component (1) and the tetracarboxylic acid component, or by polymerizing the diamine component (1) and the diamine component (2) and the tetracarboxylic acid component, and wherein the imidization rate of the polyimide obtained by imidizing the polyimide precursor is 20% or more and 80% or less. Diamine component (1): a diamine component containing a diamine having a tert-butoxycarbonyl group and a diamine having a siloxane skeleton, Diamine component (2): a diamine component containing a diamine having a tert-butoxycarbonyl group and a siloxane skeleton, The diamine having a tert-butoxycarbonyl group in the diamine component (1) is a diamine represented by the following formula [1], In formula [1], X D represents an organic group having 1 to 50 carbon atoms and having at least one structure selected from the group consisting of the following formula [1a], formula [1b] and formula [1c], 1 and A 2 each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, In formula [1a] to formula [1c], X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X d represents a single bond or an organic group having 1 to 20 carbon atoms, X e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, D represents a tert-butoxycarbonyl group, and * represents a bond.

2. The liquid crystal alignment agent according to claim 1, wherein The diamine component (2) further contains a diamine having at least one specific side chain structure selected from the group represented by the following formulas [S1] to [S3], In formula [S1], X 1 and X 2 each independently represents a single bond, -(CH2)a-, -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -COO-, -OCO- or -((CH2) a1 -A1)m1-, in the -(CH2)a-, a represents an integer of 1 to 15, wherein a plurality of a1s each independently represents an integer of 1 to 15, a plurality of A1s each independently represents an oxygen atom or -COO-, m1 represents 1 to 2, G 1 and G 2 Each independently represents a divalent cyclic group selected from the group consisting of a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms, wherein any hydrogen atom on the cyclic group is optionally substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom, and R 1 represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms, forming R 1 Any hydrogen in the group may be substituted with fluorine, m and n each independently represent an integer of 0 to 3, and the total of m and n is 1 to 4, -X 3 —R 2 [S2] In formula [S2], X 3 represents a single bond, -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CH2O-, -COO- or -OCO-, R 2 represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms, forming R 2 Any hydrogen of is optionally replaced by fluorine, -X 4 —R 3 [S3] In formula [S3], X 4 Indicates -CONH-, -NHCO-, -O-, -COO- or -OCO-, R 3 It indicates a structure having a steroidal skeleton.

3. The liquid crystal alignment agent according to claim 1, wherein The diamine having a siloxane skeleton in the diamine component (1) is a diamine represented by the following formula [2]: In formula [2], R1, R2, R3, and R4 each independently represent a methyl group or an ethyl group, X1 and X2 each independently represent a single bond, -NHCO-, -CONH-, -COO-, or -OCO-, P1 and P2 each independently represent -NH2 or a structure represented by the following formula [Pa] to [Pb], n1 and n2 each independently represent an integer of 0 to 6, and m represents an integer of 1 to 5, wherein the phenyl group in formula [Pa] to [Pb] is optionally substituted with halogen, In formula [Pa] to formula [Pb], X D2 represents an organic group having 1 to 50 carbon atoms and having at least one structure selected from the group consisting of the following formula [2a], formula [2b] and formula [2c], p represents an integer of 0 to 1, * represents a bond, In formula [2a] to formula [2c], X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X d represents a single bond or an organic group having 1 to 20 carbon atoms, X e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, D represents a tert-butoxycarbonyl group, and * represents a bond.

4. The liquid crystal alignment agent according to claim 1, wherein The diamine represented by the formula [1] is at least one diamine selected from the group consisting of the following formulas [1a-1] to [1c-1], In formula [1a-1], X 1 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 ) at least one organic group selected from the group consisting of CO-, -CH2O-, -COO-, and -OCO-, wherein R 1 , R 2 , R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X 2 represents a single bond, an alkylene group having 1 to 10 carbon atoms, and X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X b represents the structure of the following formula [a-1], m represents an integer of 1 or 2. In this case, when m is 2, X a represents a hydrogen atom, p represents an integer of 1 to 4, q represents an integer of 1 to 4, In formula [1b-1], X 3 and X 7 Each independently represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 ) at least one of the group consisting of CO-, -CH2O-, -COO- and -OCO-, wherein R 1 , R 2 , R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X 4 and X 6 Each independently represents a single bond or an alkylene group having 1 to 10 carbon atoms, and X 5 represents a single bond or an alkylene group having 1 to 10 carbon atoms, X c represents the structure of the following formula [a-1], r represents an integer of 1 to 4, In formula [1c-1], X 8 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 ) at least one of the group consisting of CO-, -CH2O-, -COO- and -OCO-, wherein R 1 , R 2 , R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X 9 represents a single bond, an alkylene group having 1 to 10 carbon atoms, and X d represents a single bond or an organic group having 1 to 20 carbon atoms, X e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X f represents the structure of the following formula [a-1], n represents an integer of 1 to 4, s represents an integer of 1 to 4, and t represents an integer of 1 to 4, In formula [1a-1] to formula [1c-1], A 1 ~A 6 each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, 5. The liquid crystal alignment agent according to claim 4, wherein: The diamine represented by the formula [1a-1] to the formula [1c-1] is at least one diamine selected from the group consisting of the following formula [1d-1] to the formula [1d-5], In formula [1d-1] to formula [1d-5], R 1 ~R 7 Each independently represents the structure of the following formula [a-1], wherein in formula [1d-1] to formula [1d-5], A 1 ~A 10 each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, 6. The liquid crystal alignment agent according to claim 3, wherein: In the diamine represented by the above formula [2], m represents 1.

7. The liquid crystal alignment agent according to claim 3, wherein: In the diamine represented by the formula [2], X D2 represents a structure selected from the following formulae [2a-1] and [2b-1], In formula [2a-1], X 1 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 ) at least one organic group selected from the group consisting of CO-, -CH2O-, -COO- and OCO-, wherein R 1 , R 2 , R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X 2 represents a single bond, an alkylene group having 1 to 10 carbon atoms, and X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X b represents the structure of the following formula [a-1], m represents an integer of 1 or 2. In this case, when m is 2, X a represents a hydrogen atom, p represents an integer of 1 to 4, q represents an integer of 1 to 4, In formula [2b-1], X 8 represents a single bond, an alkylene group having 1 to 10 carbon atoms, -O-, -N(R 1 )-、-CON(R 2 )-、-N(R 3 ) at least one of the group consisting of CO-, -CH2O-, -COO- and -OCO-, wherein R 1 , R 2 , R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X 9 represents a single bond, an alkylene group having 1 to 10 carbon atoms, and X d represents a single bond or an organic group having 1 to 20 carbon atoms, X e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X f represents the structure of the above formula [a-1], n represents an integer of 1 to 4, s represents an integer of 1 to 4, and t represents an integer of 1 to 4.

8. The liquid crystal alignment agent according to claim 3, wherein: The diamine represented by the formula [2] is a diamine represented by the following formula, 9. The liquid crystal alignment agent according to claim 1, wherein: The diamine having a tert-butoxycarbonyl group and a siloxane skeleton in the diamine component (2) is a diamine represented by the following formula [3]: In formula [3], R1, R2, R3, and R4 each independently represent a methyl group or an ethyl group, X represents -NHCO-, -CONH-, -COO-, or -OCO-, and X D2 represents an organic group having 1 to 50 carbon atoms and having at least one structure selected from the group consisting of the following formula [2a], formula [2b] and formula [2c], wherein n represents an integer of 0 to 6, m represents an integer of 1 to 5, p represents an integer of 0 to 1, and q represents an integer of 0 to 1, wherein at least one of p and q represents 1, In formula [2a] to formula [2c], X a represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, X d represents a single bond or an organic group having 1 to 20 carbon atoms, X e represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, D represents a tert-butoxycarbonyl group, and * represents a bond.

10. The liquid crystal alignment agent according to claim 1, wherein The tetracarboxylic acid component is a tetracarboxylic acid compound represented by the following formula [4]: In the formula [4], Z 1 represents at least one structure selected from the group consisting of the following formula [4a] to formula [4q], In formula [4a], Z 1 ~Z 4 Each independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a benzene ring. In the formula [4g], Z 5 and Z 6 Each independently represents a hydrogen atom or a methyl group.

11. The liquid crystal alignment agent according to claim 1, wherein: The diamine component (1) further contains a diamine having at least one specific side chain structure selected from the group represented by the following formulas [S1] to [S3], In formula [S1], X 1 and X 2 Each independently represents a single bond, -(CH2) a -, -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -COO-, -OCO- or -((CH2) a1 -A1) m1 -, said -(CH2) a -, a represents an integer of 1 to 15, wherein a1 each independently represents an integer of 1 to 15, a1 each independently represents an oxygen atom or -COO-, m1 represents 1 to 2, G 1 and G 2 Each independently represents a divalent cyclic group selected from the group consisting of a divalent aromatic group having 6 to 12 carbon atoms and a divalent alicyclic group having 3 to 8 carbon atoms, wherein any hydrogen atom on the cyclic group is optionally substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom, and R 1 represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms, forming R 1 Any hydrogen in the group may be substituted with fluorine, m and n each independently represent an integer of 0 to 3, and the total of m and n is 1 to 4, -X3—R2[S2] In formula [S2], X 3 represents a single bond, -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CH2O-, -COO- or -OCO-, R 2 represents an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group having 2 to 20 carbon atoms, forming R 2 Any hydrogen of is optionally replaced by fluorine, -X4—R3[S3] In formula [S3], X 4 Indicates -CONH-, -NHCO-, -O-, -COO- or -OCO-, R 3 It indicates a structure having a steroidal skeleton.

12. The liquid crystal alignment agent according to claim 1, wherein The diamine component (1) and the diamine component (2) further contain two side chain diamines represented by the following formula [N1], In the formula [N1], X represents a single bond, -O-, -C(CH3)2-, -NH-, -CO-, -NHCO-, -COO-, -(CH2)m-, -SO2- or a divalent organic group composed of any combination thereof, m represents an integer of 1 to 8, and Y each independently represents a structure of the following formula [1-1], In the formula [1-1], Y 1 and Y 3 Each independently represents a single bond, -(CH2)a-, -O-, -CH2O-, -COO- or -OCO-, wherein -(CH2) a -, a represents an integer from 1 to 15, Y 2 Represents a single bond or -(CH2) b -, said -(CH2) b -, b represents an integer from 1 to 15, wherein 1 or Y 3 Represents a single bond or -(CH2) a - In the case of Y 2 Indicates a single bond. In addition, 1 represents -O-, -CH2O-, -COO- or -OCO-, and / or Y 3 When Y represents -O-, -CH2O-, -COO-, or -OCO-, 2 Represents a single bond or -(CH2) b - Y 4 represents at least one divalent cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocyclic ring, or a divalent organic group having 17 to 51 carbon atoms and having a steroidal skeleton, wherein any hydrogen atom forming the cyclic group is optionally substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom, Y 5 represents at least one cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocyclic ring, wherein any hydrogen atom forming the cyclic group is optionally substituted with an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorinated alkyl group having 1 to 3 carbon atoms, a fluorinated alkoxy group having 1 to 3 carbon atoms, or a fluorine atom, Y 6 represents at least one selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorinated alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, and a fluorinated alkoxy group having 1 to 18 carbon atoms, and n represents an integer of 0 to 4.

13. The liquid crystal alignment agent according to claim 1, wherein The content of the diamine represented by the formula [1] is 5 to 70 mol% in 100 mol% of all diamine components.

14. The liquid crystal alignment agent according to claim 3, wherein: The content of the diamine represented by the formula [2] is 1 to 50 mol% in 100 mol% of all diamine components. 15 . A liquid crystal alignment film obtained from the liquid crystal alignment agent according to claim 1 . 16 . A liquid crystal display element comprising the liquid crystal alignment film according to claim 15 .

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