WO2021005888A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal element - Google Patents

Abstract

A liquid crystal alignment agent that exhibits a good coatability on substrates, and with which good pretilt angle characteristics can be obtained using a photoalignment method, is provided by the incorporation in the liquid crystal alignment agent of a polymer (A) that has a photoalignment group and a structural unit (M1) derived from a spiro ring-containing monomer.

Description

Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element Cross-reference of related applications

This application is based on Japanese Patent Application No. 2019-129596 filed on July 11, 2019, and the contents of the description are incorporated herein by reference.

The present disclosure relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal element.

The liquid crystal element includes a liquid crystal alignment film that orients liquid crystal molecules in a certain direction. The liquid crystal alignment film is generally formed by applying a liquid crystal alignment agent in which a polymer component is dissolved in an organic solvent to a substrate, and preferably heating the substrate. As the polymer component of the liquid crystal alignment agent, polyamic acid and soluble polyimide have been used for a long time because of their excellent mechanical strength, liquid crystal orientation, and affinity with liquid crystals (see, for example, Patent Document 1). ..

The photo-alignment method has been proposed as an alternative technique to the rubbing method as a method for imparting liquid crystal alignment ability to a polymer thin film formed by a liquid crystal alignment agent. The photoalignment method is a method of controlling the orientation of a liquid crystal by irradiating a radiation-sensitive organic thin film formed on a substrate with polarized or unpolarized radiation to give anisotropy to the film. Conventionally, various liquid crystal alignment agents have been proposed in order to form a liquid crystal alignment film by a photoalignment method (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2011-257736 Japanese Unexamined Patent Publication No. 2011-158835

The angle (pre-tilt angle) formed by the long axis of the liquid crystal molecule and the substrate surface greatly affects the display characteristics of the liquid crystal element. The present inventors use the photoalignment method so that the long axis of the liquid crystal molecules is tilted at an angle lower than the vertical direction (for example, the pretilt angle is 89 degrees or less) in the initial state when no voltage is applied to the liquid crystal element. By controlling the orientation of the liquid crystal, we tried to obtain a liquid crystal element with higher definition than before. However, when a conventional alignment film material is used, it has been found that the long axis of the liquid crystal molecules cannot be sufficiently inclined with respect to the vertical direction in the initial state, and it is difficult to reduce the pretilt.

In addition, the present inventors have studied to make the structure of the polymer component constituting the liquid crystal alignment film rigid in order to reduce the pretilt by controlling the photoorientation. However, there is a trade-off relationship between the rigidity of the polymer structure and the solubility of the polymer, and when the polymer structure is attempted to be rigid, the solubility of the polymer tends to decrease. If the polymer component is not uniformly dissolved in the solvent, the liquid crystal alignment film formed on the substrate may have uneven coating, and a flat film may not be formed. In this case, there is a concern that the product yield may decrease and the display performance such as liquid crystal orientation and electrical characteristics may be affected.

The present disclosure has been made in view of the above circumstances, and its main purpose is to provide a liquid crystal alignment agent which can obtain good pre-tilt angle characteristics by a photoalignment method and has good coatability on a substrate.

The present inventors have diligently studied to solve the above problems, focused on introducing a spiro skeleton into a polymer, and found that the above problems can be solved by using a monomer having a spiro ring. Specifically, according to the present disclosure, the following means are provided.
[1] A liquid crystal aligning agent containing a polymer (A) having a structural unit (M1) derived from a monomer having a spiro ring and having a photo-oriented group.
[2] A liquid crystal alignment film formed by using the liquid crystal alignment agent of the above [1].
[3] A liquid crystal element provided with the liquid crystal alignment film of the above [2].
[4] A polymer having a structural unit having a spiro ring and having a photo-oriented group.

By incorporating the polymer (A) in the liquid crystal alignment agent, good pretilt angle characteristics can be obtained by the photoalignment method while ensuring good coatability of the liquid crystal alignment agent on the substrate.

The matters related to the present disclosure will be described in detail below.
≪Liquid crystal alignment agent≫
The liquid crystal alignment agent of the present disclosure contains a polymer (A) having a structural unit (M1) derived from a monomer having a spiro ring and having a photo-oriented group.

<Polymer (A)>
-Photo-orientation group The photo-orientation group of the polymer (A) is a functional group that imparts anisotropy to the film by photoisomerization reaction, photodimerization reaction, photofries rearrangement reaction, or photodecomposition reaction by light irradiation. Is. The polymer (A) preferably has a photo-oriented group in the side chain. Specific examples of the photo-orientating group include an azobenzene-containing group containing azobenzene or a derivative thereof as a basic skeleton, a lauric acid structure-containing group containing katsura acid or a derivative thereof (katsura acid structure) as a basic skeleton, and a chalcone or a derivative thereof. A chalcone-containing group contained as a skeleton, a benzophenone-containing group containing benzophenone or a derivative thereof as a basic skeleton, a coumarin-containing group containing coumarin or a derivative thereof as a basic skeleton, a phenylbenzoate-containing group containing phenylbenzoate or a derivative thereof as a basic skeleton, cyclobutane or Examples thereof include a cyclobutane-containing structure containing the derivative as a basic skeleton.

The photo-oriented group contained in the polymer (A) is preferably a cinnamic acid structure-containing group among the above in terms of high photosensitivity. Specifically, it is preferable that the group contains a cinnamic acid structure represented by the following formula (2) as a basic skeleton.

In formula (2), R ¹¹ and R ¹² are independently hydrogen atoms, fluorine atoms, cyano groups, alkyl groups having 1 to 3 carbon atoms, or fluoroalkyl groups having 1 to 3 carbon atoms, respectively. ^Reference numeral ¹³ denotes an alkyl group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group, and an alkoxy group having 1 to 10 carbon atoms, at least one. The hydrogen atom is a substituted alkoxy group having 1 to 10 carbon atoms, a fluorine atom, or a cyano group substituted with a fluorine atom or a cyano group. A is an integer of 0 to 4. When a is 2 or more, a plurality of R ¹³ is the same group or a different group. “*” Indicates that it is a binder.)

In the structure represented by the above formula (2), R ¹¹ and R ¹² are both hydrogen atoms in that the photoreactivity can be made higher, or one is a hydrogen atom and the other (preferably R). ¹² ) is preferably an alkyl group having 1 to 3 carbon atoms.
R ¹³ is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. The a is preferably 0 to 2, more preferably 0 or 1.

One of the two bonding hands "*" in the above formula (2) is preferably bonded to a group having a ring in that the pretilt angle of the obtained liquid crystal element can be controlled more preferably. .. Specifically, one of the two bonds "*" in the above formula (2) is preferably a bond with a group represented by the following formula (3).

(In the formula (3), when X ^1A is bonded to the phenyl group in the formula (2), it is a single bond, an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom, a sulfur atom, -CH =. When it is CH-, -NH-, -COO- or -OCO- and is bonded to the carbonyl group in the formula (2), it is a single bond, an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom, It is a sulfur atom or -NH-. R ¹⁴ and R ¹⁵ are independently substituted or unsubstituted phenylene groups, or substituted or unsubstituted cyclohexylene groups. X ^1B is a single bond and carbon number. 1 to 3 alkanediyl groups, oxygen atom, sulfur atom, -CH = CH-, -NH-, -COO- or -OCO-. R ¹⁶ is an alkyl group having 1 to 20 carbon atoms and 1 carbon atom. ~ 20 alkoxy groups, at least one hydrogen atom substituted with a fluorine atom or a cyano group, a substituted alkyl group having 1 to 20 carbon atoms, at least one hydrogen atom substituted with a fluorine atom or a cyano group. It is a substituted alkoxy group of 1 to 10, a fluorine atom, a cyano group, a phenyl group or a cyclohexyl group. R is an integer of 0 to 3. When r is 2 or more, a plurality of R ^15s are the same group or groups of each other. It is a different group, and a plurality of ^X1Bs are the same group or different groups from each other. “*” Indicates that it is a binder.)

In the above formula (3), the substituent bonded to the ring of the phenylene group and the cyclohexylene group is preferably an alkyl group having 1 to 3 carbon atoms, a fluorine atom or a cyano group. r is preferably 0 to 2. When R ¹⁶ is an alkyl group or an alkoxy group having 1 to 20 carbon atoms, R ¹⁶ preferably has 2 or more carbon atoms, and more preferably 3 or more carbon atoms.

・ Structural unit (M1)
The structural unit (M1) is a structural unit derived from a monomer having a spiro ring (hereinafter, also referred to as “monomer A”). The spiro ring contained in the monomer A may have a skeleton formed by combining a plurality of monocycles, or may have a skeleton in which at least one of the constituents is a condensed ring or a crosslinked ring. Good. Further, the ring constituting the spiro ring may be either a hydrocarbon ring or a heterocycle. From the viewpoint of achieving both low pretilt angle and solubility of the polymer, the number of ring members of each component ring forming the spiro bond is preferably 4 to 20, preferably 4 to 13. More preferably.

The spiro ring contained in the monomer A may have a substituent at the ring portion. Examples of the substituent include an alkyl group having 1 to 5 carbon atoms, an alkyl halide group having 1 to 5 carbon atoms, a hydroxyl group, an oxo group, a halogen atom and the like. The number of spiro atoms contained in the monomer A is preferably 1 or 2, and more preferably 1 from the viewpoint of the balance between low pretilt and solubility of the polymer.

-Other structural unit The polymer (A) may be a polymer consisting of only the structural unit (M1), but from the viewpoint of improving the solubility of the polymer (A), the structural unit (M1) It is preferable to further have a structural unit different from the above (hereinafter, also referred to as “other structural unit”). When the polymer (A) has a structural unit (M1) and other structural units, the structural unit (M1) may have a photo-oriented group, and the other structural unit may have a photo-oriented group. You may have. The polymer (A) has a spiro ring as another structural unit because it can increase the degree of freedom in selecting the monomer A and the content ratio of the photo-oriented group in the polymer can be easily adjusted. It is preferable to have a structural unit (M2) having a photo-oriented group.

In the polymer (A), the content ratio of the structural unit (M1) is the total amount of the structural units derived from the monomers constituting the polymer (A) from the viewpoint of sufficiently obtaining the effect of lowering the pretilt angle. On the other hand, it is preferably 5 mol% or more, more preferably 10 mol% or more, and further preferably 20 mol% or more. The content ratio of the structural unit (M1) is 95 mol% or less with respect to the total amount of the structural units derived from the monomers constituting the polymer (A) from the viewpoint of ensuring the solubility of the polymer. It is preferably 90 mol% or less, more preferably 80 mol% or less.

-Main skeleton The main skeleton of the polymer (A) is not particularly limited. The polymer (A) is polymerized using a monomer having a spiro atom and two polymerizable groups in the main chain (for example,) in that the effect of lowering the pretilt angle can be sufficiently obtained. It is preferably a polymer obtained by polycondensation, polyaddition or nucleophilic substitution polymerization). Among these, the polymer (A) is at least one selected from the group consisting of polyamic acid, polyimide, polyamic acid ester, polyenamine and polyamine from the viewpoint of affinity with liquid crystal molecules, liquid crystal orientation, and mechanical strength. It is more preferable that it is at least one selected from the group consisting of polyamic acid, polyimide and polyamic acid ester.

The polymer (A) can be synthesized according to the standard method of organic chemistry according to its main skeleton. When the polymer (A) is a polyamic acid, the polyamic acid (hereinafter, also referred to as "polyamic acid (A)") can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound. .. Specifically, as the monomer A, a tetracarboxylic dianhydride having a spiro ring (hereinafter, also referred to as “specific acid dianhydride”) and a diamine compound having a spiro ring (hereinafter, also referred to as “specific dimer”). By using one or both of the above), a polyamic acid having a structural unit having a spiro ring and a photoaligning group can be obtained.

-Specific acid dianhydride The specific acid dianhydride has a spiro ring and two acid anhydride groups (* ¹ -CO-O-CO- * ¹ (however, the two "* ¹ " are the same, respectively). The molecular structure is not particularly limited as long as it has a carbon atom of the above or a bonder that binds to a different carbon atom.)). At least one of the two acid anhydride groups of the specific acid dianhydride may be contained in the spiro ring.

The specific acid dianhydride is at least one selected from the group consisting of a compound represented by the following formula (4), a compound represented by the following formula (5), and a compound represented by the following formula (6). Is preferable.

(In the formula (4), W ¹ to W ⁴ are independently single bonds or alkanediyl groups having 1 to 10 carbon atoms.)

(In the formula (5), W ⁵ to W ⁸ are independently single bonds or alkanediyl groups having 1 to 10 carbon atoms. X ¹ is an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom or an oxygen atom. -NH-.)

(In formula (6), Y ¹ to Y ⁴ are independently single bonds, oxygen atoms, or alkanediyl groups having 1 to 10 carbon atoms. However, ^one of Y ¹ and Y ² is an oxygen atom. Or, in the case of a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms, and when one of Y ³ and Y ⁴ is an oxygen atom or a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms. . X ² and X ³ are independent oxygen atoms, sulfur atoms, -COO-, -OCO-, -NHCO- or -CONH-. R ¹ to R ⁴ are independent carbon atoms, respectively. It is an alkyl group having the number 1 to 5, an alkoxy group having 1 to 5 carbon atoms, a phenyl group, a halogen atom or a hydroxyl group. N1 and n2 are 0 or 1, respectively. T1 to t4 are independent, respectively. It is an integer of 0 to 2. When a plurality of R ¹ to R ⁴ are present in the formula, the plurality of groups are the same group or different groups.)

In the above formulas (4) to (6), when W ¹ to W ⁴ , W ⁵ to W ⁸ , and Y ¹ to Y ⁴ are alkanediyl groups having 1 to 10 carbon atoms, the alkanediyl groups are linear. It may be in the form of a branch or a branch. Specific examples thereof include a methylene group, an ethylene group, a 1,3-propanediyl group, a 2,2-propanediyl group, a 1,4-butandyl group, a 1,2-butandyl group, a 3,3-pentanediyl group and the like. Can be mentioned. W ¹ to W ⁴ and W ⁵ to W ⁸ are preferably single bonds or alkanediyl groups having 1 to 3 carbon atoms.
For Y ¹ to Y ⁴ , the ring formed by Y ¹ , Y ² , and the three carbon atoms to which Y ¹ and Y ² are bonded, and Y ³ , Y ⁴ , and Y ³ and Y ⁴ are The ring formed by the three carbon atoms to be bonded preferably has a ring member number of 5 to 7, and more preferably a ring member number of 5 or 6.
X ¹ is preferably a methylene group or an ethylene group.
Regarding n1 and n2, from the viewpoint of polymer solubility, at least one of n1 and n2 is preferably 0, and n1 and n2 are more preferably 0.

Specific examples of the specific acid dianhydride include compounds represented by the following formulas (4-1) to (4-5) as compounds represented by the above formula (4); As the compound represented by 5), the compound represented by each of the following formulas (5-1) to (5-3) and the like; as the compound represented by the above formula (6), the following formula (6-- Compounds and the like represented by each of 1) to the formula (6-6) can be mentioned.

In the synthesis of the polyamic acid (A), a tetracarboxylic dianhydride having no spiro ring (hereinafter, also referred to as "other acid dianhydride") may be used as the tetracarboxylic dianhydride. Good. When a specific diamine is used as the monomer A in the synthesis of the polyamic acid (A), only other acid dianhydrides may be used as the tetracarboxylic dianhydride in the synthesis. Examples of other acid dianhydrides include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aromatic tetracarboxylic dianhydrides.

Specific examples of other acid dianhydrides include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride;
Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and the like. 2,3,5-tricarboxycyclopentylacetic dianhydride, 5- (2,5-dioxotetraxtetra-3-yl) -3a,4,5,9b-tetrahydronaphtho [1,2-c] furan-1 , 3-Dione, 5- (2,5-dioxotetrakitetra-3-yl) -8-methyl-3a, 4,5,9b-tetrahydronaphtho [1,2-c] furan-1,3-dione, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, etc. ;
Aromatic tetracarboxylic acid dianhydrides include, for example, pyromellitic anhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, ethylene glycol bisanhydrotrimate, 4,4'-(hexafluoro). Isopropylidene) diphthalic anhydride, 4,4'-carbonyldiphthalic anhydride, 4,4'-oxydiphthalic anhydride, propane-1,3-diylbis (1,3-dioxo-1,3-dihydroiso) Benzofuran-5-carboxylate) and the like can be mentioned, respectively, and the tetracarboxylic acid dianhydride described in JP-A-2010-97188 can be used. As other acid dianhydrides, one type can be used alone or in combination of two or more types.

When a specific acid dianhydride is used in the synthesis of polyamic acid (A), the ratio of the specific acid dianhydride used to the total amount of the tetracarboxylic dianhydride used is the low angle of the pretilt angle due to the specific acid dianhydride. From the viewpoint of sufficient conversion, the content is preferably 10 mol% or more, more preferably 20 mol% or more, and more preferably 40 mol% or more, based on the total amount of the tetracarboxylic dianhydride used for the synthesis. Is even more preferable. As the specific acid dianhydride, only one type may be used, or two or more types may be used in combination.

Specific acid dianhydrides are available in Bulletin of the Chemical Society of Japan, 72, 5, 1075-1081 (1999), Journal of the Chemical Society, 121, 1644 (1922), Justus Liebigs Annalen der Chemie, 593, 1-17. (1955), Journal of Materials Chemistry, 7, 4, 589-592 (1997), Japanese Patent No. 4035365, US Patent No. 5216173, US Patent Application Publication No. 2018/371168, Taiwan Patent Application Publication It can be synthesized according to the description of No. 2017/31851. Further, the compound in which n1 and n2 in the above formula (6) is 1 (that is, the compound represented by the following formula (6A)) is, for example, a bisphenol having a spiro ring and a trimellitic anhydride halide in the third grade. It can be obtained by reacting in an organic solvent in the presence of amine, if necessary. The method for synthesizing the specific acid dianhydride is not limited to the above.

(In the formula ^{(6A), Y 1 ~ Y} 4, X 2, X 3, R 5 ~ R 8 and t1 ~ t4 are each defined in the above formula (6).)

-Specific diamine The molecular structure of the specific diamine is not particularly limited as long as it has a spiro ring and two amino groups (primary amino group or secondary amino group). The specific diamine is preferably an aromatic diamine in that the electrical characteristics of the liquid crystal element can be improved and the degree of freedom in molecular design can be increased. Specifically, the compound represented by the following formula (7). Is preferable.

(In formula (7), Y ⁵ to Y ⁸ are independently single bonds, oxygen atoms, or alkanediyl groups having 1 to 10 carbon atoms. However, one of Y ⁵ and Y ⁶ is an oxygen atom. Or, in the case of a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms, and when one of Y ⁷ and Y ⁸ is an oxygen atom or a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms. . X ⁴ and X ⁵ are independently oxygen atoms, sulfur atoms, -COO-, -OCO-, -NHCO- or -CONH-. R ⁵ and R ⁶ are independent carbons, respectively. It is an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a phenyl group, a halogen atom or a hydroxyl group. R ⁷ and R ⁸ are independently alkyl groups having 1 to 5 carbon atoms and carbon atoms. 1 to 5 alkoxy groups, phenyl groups, monovalent groups having photoorientation groups, halogen atoms or hydroxyl groups. N3 and n4 are independently 0 or 1, respectively. T5 to t8 are independent, respectively. When there are a plurality of R ⁵ to R ⁸ in the equation, the plurality of groups are the same group or different groups.)

In the above formula (7), the description of Y ¹ to Y ^{4 in} the above formula (6) is applied to the explanation when Y ⁵ to Y ⁸ are alkanediyl groups having 1 to 10 carbon atoms.
For Y ⁵ to Y ⁸ , the ring formed by Y ⁵ , Y ⁶ , and the three carbon atoms to which Y ⁵ and Y ⁶ are bonded, and Y ⁷ , Y ⁸ , and Y ⁷ and Y ⁸ are The ring formed by the three carbon atoms to be bonded preferably has a ring member number of 5 to 7, and more preferably a ring member number of 5 or 6.
From the viewpoint of polymer solubility, at least one of n3 and n4 is preferably 0, and more preferably both n3 and n4 are 0.

Regarding the case where R ⁷ and R ⁸ are monovalent groups having a photo-oriented group (hereinafter, also referred to as “group R”), the description of the photo-oriented group contained in the group R is based on the polymer (A). The above description regarding the photooriented group having is applied. From the viewpoint of further reducing the pretilt angle, the group R is preferably a group represented by the following formula (8).

(In formula (8), X ⁶ is an oxygen atom or -NH-. R ²¹ and R ²² are independently hydrogen atoms, fluorine atoms, cyano groups, alkyl groups having 1 to 3 carbon atoms, or alkyl groups having 1 to 3 carbon atoms. It is a fluoroalkyl group having 1 to 3 carbon atoms. R ²³ is a substituent. R ²⁴ is a monovalent organic group having 1 to 30 carbon atoms. A1 is an integer of 0 to 4. A1 is 2. In the above case, the plurality of R ^23s are the same group or different groups. “*” Indicates that the bond is a bond.)

In the above formula (8), R ²⁴ is preferably a group represented by the above formula (3).
The substituent of R ²³ is an alkyl group having 1 to 3 carbon atoms, a substituted alkyl group having 1 to 3 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group, and an alkoxy group having 1 to 3 carbon atoms. , A substituted alkoxy group having 1 to 10 carbon atoms, a fluorine atom, or a cyano group in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group is preferable.
As for the description of R ²¹ and R ^22, the description of R ¹¹ and R ^{12 in} the above formula (2) is applied.

Specific examples of the specific diamine include compounds represented by the following formulas (7-1) to (7-12).

(In equations (7-9) to (7-12), n is an integer from 1 to 20.)

In synthesizing the polyamic acid (A), a diamine compound having no spiro ring (hereinafter, also referred to as "other diamines") may be used as the diamine compound. When a specific acid dianhydride is used as the monomer A in the synthesis of the polyamic acid (A), only other diamines may be used as the diamine compound in the synthesis. Examples of other diamines include aliphatic diamines, alicyclic diamines, and aromatic diamines.

Specific examples of other diamines include m-xylylenediamine, 1,3-propanediamine, hexamethylenediamine and the like as aliphatic diamines;
As an alicyclic diamine, 1,4-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine), etc. are used;
As aromatic diamines, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5 -Diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, 3,5-diaminobenzoate Ranostanate acid, 3,6-bis (4-aminobenzoyloxy) cholesterol, 3,6-bis (4-aminophenoxy) cholesterol, 2,4-diamino-N, N-diallylaniline, 4- (4'-tri) Fluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butylcyclohexane, 3,5-diaminobenzoic acid = 5ξ-cholestane- 3-Il, the following formula (E-1)

(In the formula (E-1), X ^I and X ^II are independently single-bonded, -O-, * -COO- or * -OCO- (where "*" is a bond with X ^I. shown.) is .R ^I is .b a is .a alkanediyl group ^{.R II} is a single bond or a C 1-3 alkanediyl group of 1 to 3 carbon atoms is 0 or 1 0 It is an integer of ~ 2. c is an integer of 1 to 20. D is 0 or 1. However, a and b cannot be 0 at the same time.)
Side chain diamines such as compounds represented by, diamines having a photo-oriented group in the side chain:

p-Phenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis (4-aminophenoxy) Pentan, 1,2-bis (4-aminophenoxy) ethane, bis [2- (4-aminophenyl) ethyl] hexanedioic acid, N, N-bis (4-aminophenyl) methylamine, 1,4-bis -(4-Aminophenyl) -piperazin, N, N'-bis (4-aminophenyl) -benzidine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) ) -4,4'-Diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis (4-aminophenyl) hexafluoropropane , 4,4'-(phenylenediisopropyridene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-[4,4 '-Propane-1,3-diylbis (piperidin-1,4-diyl)] dianiline, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenylamine, 1,3-bis (4-aminophenethyl) urea , 1,3-bis (4-aminobenzyl) urea, 1,4-bis (4-aminophenyl) -piperazin, N, N'-bis- (4-aminophenylethyl) -N-methylamine, N, Mainly N'-bis (4-aminophenyl) -N, N'-dimethylbenzidine, N4, N4'-bis- (4-aminophenyl) -N4, N4'-dimethylbiphenyl-4,4'-diamine, etc. Chain type diamine etc .;
As the diaminoorganosiloxane, for example, 1,3-bis (3-aminopropyl) -tetramethyldisiloxane and the like can be mentioned, and the diamine described in JP-A-2010-97188 can be used. As the other diamines, one type can be used alone or two or more types can be used in combination.

When a specific diamine is used in the synthesis of the polyamic acid (A), the ratio of the specific diamine to the total amount of the diamine compound used is the diamine used in the synthesis from the viewpoint of sufficiently reducing the pretilt angle by the specific diamine. It is preferably 10 mol% or more, more preferably 20 mol% or more, and further preferably 40 mol% or more based on the total amount of the compound. As the specific diamine, only one type may be used, or two or more types may be used in combination.

Specific diamines are Bulletin of the Chemical Society of Japan, 44, 496-505, 617-623, 2177-2181 (1971), Journal of the American Chemical Society; vol.122; nb.9; (2000); p. It can be synthesized according to the description of 2053-2061, Bulletin of the Korean Chemical Society; vol.34; nb.12; (2013); p.3888-3890 and the like. Further, among the compounds represented by the above formula (7), at least one of R ⁷ and R ⁸ is a monovalent group having a photo-oriented group (a compound represented by the following formula (7A)). Can be obtained, for example, by acid-chloriding a carboxylic acid having a photo-oriented group with an appropriate chlorinating agent and then reacting it with a bisphenol having a spiro ring in an organic solvent, if necessary. The method for synthesizing the specific diamine is not limited to the above.

(In the formula (7A), Y ⁵ to Y ⁸ , X ⁴ , X ⁵ are R ⁵ , R ⁶ , n3, n4, and t5 to t 8 are synonymous with the above formula (7). R ¹⁷ is synonymous with the above formula (7). It is an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a phenyl group, a monovalent group having a photo-oriented group, a halogen atom or a hydroxyl group. R ¹⁸ is 1 having a photo-oriented group. It is the basis of the value.)

It is preferable that the polymer (A) has a spiro ring in the main chain in that the effect of improving the low pretilt can be further enhanced. From this point of view, the polyamic acid (A) to be blended in the liquid crystal alignment agent is selected from the group consisting of the compound represented by the above formula (6) and the compound represented by the above formula (7) as the structural unit (M1). It is preferable to have a structural unit derived from at least one compound (hereinafter, also referred to as “structural unit U”). The ratio of the structural unit U contained in the polyamic acid (A) is preferably 5 mol% or more, preferably 10 mol% or more, based on the total amount of the structural units derived from the monomers used in the synthesis of the polyamic acid (A). More preferably, it is more preferably 20 mol% or more. Further, the ratio of the structural unit U contained in the polyamic acid (A) is preferably 90 mol% or less with respect to the total amount of the structural units derived from the monomers used in the synthesis of the polyamic acid (A). More preferably, it is 80 mol% or less.

-Synthesis of polyamic acid A polyamic acid can be obtained by reacting a tetracarboxylic dianhydride and a diamine compound with a molecular weight regulator (for example, acid monoanhydride or monoamine), if necessary. The ratio of the tetracarboxylic dianhydride and the diamine compound used in the polyamic acid synthesis reaction is 0.2 to 0.2 to 1 equivalent of the amino group of the diamine compound for the acid anhydride group of the tetracarboxylic dianhydride. A ratio of 2 equivalents is preferable.

The polyamic acid synthesis reaction is preferably carried out in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., and the reaction time is preferably 0.1 to 24 hours. Examples of the organic solvent used in the reaction include aprotonic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Particularly preferred organic solvents are N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol. And one or more selected from the group consisting of halogenated phenol can be used as a solvent, or a mixture of one or more of these with another organic solvent (for example, butyl cellosolve, diethylene glycol diethyl ether, etc.) can be used. preferable. The amount of the organic solvent used (a) shall be such that the total amount (b) of the tetracarboxylic dianhydride and the diamine is 0.1 to 50% by mass with respect to the total amount (a + b) of the reaction solution. Is preferable.

-When the polyamic acid ester polymer (A) is a polyamic acid ester, the polyamic acid ester (hereinafter, also referred to as "polyamic acid ester (A)") was obtained by, for example, [I] the above synthetic reaction. A method of reacting a polyamic acid (A) with an esterifying agent, a method of reacting a [II] tetracarboxylic acid diester with a diamine compound containing a specific diamine, [III] a tetracarboxylic acid diester dihalide and a specific diamine. It can be obtained by a method of reacting with a containing diamine compound or the like. The polyamic acid ester (A) may have only an amic acid ester structure, or may be a partial esterified product in which an amic acid structure and an amic acid ester structure coexist.

-When the polyimide polymer (A) is a polyimide, the polyimide (hereinafter, also referred to as "polyimide (A)") dehydrates and closes the polyamic acid (A) synthesized as described above to imidize it. It can be obtained by doing. The imidization ratio of the polyimide is preferably 99% or less, and more preferably 20 to 95%. The imidization ratio is the ratio of the number of imide ring structures to the total of the number of amic acid structures and the number of imide ring structures of polyimide expressed as a percentage.

The dehydration ring closure of the polyamic acid (A) is preferably carried out by dissolving the polyamic acid (A) in an organic solvent, adding a dehydrating agent and a dehydration ring closure catalyst to the polymer solution, and heating as necessary. It is said. In this method, examples of the dehydrating agent include acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride. The amount of the dehydrating agent used is preferably 0.01 to 20 mol with respect to 1 mol of the amic acid structure of the polyamic acid (A). As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collagen, lutidine, and triethylamine can be used. In the synthesis, the amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent used. Examples of the organic solvent used in the dehydration ring closure reaction include organic solvents exemplified as those used in the synthesis of polyamic acids. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C. The reaction time is preferably 1.0 to 120 hours.

The polyimide (A) preferably has a spiro ring in the main chain in that the effect of improving the reduction of the pretilt angle can be further enhanced. The polyimide (A) having a spiro ring in the main chain of the polymer is, for example, a group consisting of [1] an acid dianhydride represented by the above formula (6) and a diamine compound represented by the above formula (7). A method of introducing a spiro ring into the main chain of a polymer by polymerizing using at least one selected from the above, and then dehydrating and imidizing the ring; [2] Acid diary represented by the above formula (4). A spiro ring is formed in the main chain of the polymer by polymerizing using at least one selected from the group consisting of an anhydride and an acid dianhydride represented by the above formula (5), dehydrating and closing the ring to imidize. Examples thereof include a method of forming (see Scheme A below).

(In Scheme A, R ³⁰ is a divalent organic group.)

-Polyenamine Polyenamine is a polymer having a carbon-carbon double bond at the position adjacent to the amino group of the polyamine, and examples thereof include polyenaminoketone, polyenaminoester, polyenaminonitrile, and polyenaminosulfonyl. When the polymer (A) is a polyenamine, the polyenamine (hereinafter, also referred to as "polyenamine (A)") can be obtained by reacting an α, β-unsaturated compound with a diamine compound containing a specific diamine. it can. Examples of the α, β-unsaturated compound used for the synthesis of polyenamine (A) include compounds represented by the following formulas (e-1) to (e-8).

The method for synthesizing polyenamine is not particularly limited, but it can be synthesized, for example, by vinyl nucleophilic substitution polymerization. This synthetic reaction is preferably carried out in an organic solvent. Examples of the organic solvent used in the reaction include aprotonic polar solvents (N-methyl-2-pyrrolidone, N, N-dimethylacetamide, etc.), phenolic solvents (phenol, cresol, etc.), alcohols, ketones, esters, ethers, etc. Examples thereof include halogenated hydrocarbons and hydrocarbons. In the synthesis, the reaction temperature is preferably −20 ° C. to 150 ° C., and the reaction time is preferably 0.1 to 24 hours. The above reaction may be carried out in the presence of a catalyst such as trifluoroacetic acid, if necessary.

-When the polyamide polymer (A) is a polyamide, the polyamide (hereinafter, also referred to as "polyamide (A)") can be obtained by reacting a dicarboxylic acid or a dicarboxylic anhydride with a diamine compound containing a specific diamine. Can be done. Examples of the dicarboxylic acid used for the synthesis of the polyamide (A) include an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, and an aromatic dicarboxylic acid. It is preferable that these dicarboxylic acids are acid chlorided with an appropriate chlorinating agent such as thionyl chloride and then subjected to a reaction with a diamine compound. Examples of the dicarboxylic acid anhydride include compounds represented by the following formulas (f-1) to (f-8).

The polyamide synthesis reaction is preferably carried out in an organic solvent. Examples of the organic solvent used in the reaction include aprotonic polar solvents (N-methyl-2-pyrrolidone, N, N-dimethylacetamide, etc.), phenolic solvents (phenol, cresol, etc.), alcohols, ketones, esters, ethers, etc. , Halogenated hydrocarbons, hydrocarbons and the like. In the synthesis, the reaction temperature is preferably −20 ° C. to 150 ° C., and the reaction time is preferably 0.1 to 24 hours.

The polymer (A) preferably has a solution viscosity of 10 to 800 mPa · s, more preferably 15 to 500 mPa · s, prepared and measured under the conditions described below. The solution viscosity (mPa · s) is determined by using an E-type rotational viscometer for a polymer solution having a concentration of 10% by mass prepared using a good solvent for the polymer (for example, N-methyl-2-pyrrolidone, etc.). It is a value measured at 25 ° C. using.

The polystyrene-equivalent weight average molecular weight (Mw) of the polymer (A) measured by gel permeation chromatography (GPC) is preferably 1,000 to 300,000, more preferably 2,000 to 100,000. Is. The molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC is preferably 7 or less, more preferably 5 or less. The polymer (A) used for preparing the liquid crystal alignment agent may be only one type or a combination of two or more types.

The content ratio of the polymer (A) in the liquid crystal aligning agent is preferably 0.1% by mass or more with respect to the total amount of the polymer contained in the liquid crystal aligning agent from the viewpoint of sufficiently reducing the pretilt. , 0.5% by mass or more, and even more preferably 1% by mass or more. Further, from the viewpoint of improving the coatability of the liquid crystal alignment agent on the substrate, the content ratio of the polymer (A) is preferably 90% by mass or less with respect to the total polymer contained in the liquid crystal alignment agent. It is more preferably 70% by mass or less, and further preferably 50% by mass or less.

It is not clear why the polymer (A) was added to reduce the pretilt of the liquid crystal element while ensuring the coatability of the liquid crystal conformer, but one hypothesis is that the spiro ring It is presumed that the solubility of the polymer was ensured by the monomer unit having the above, and the main chain was sufficiently immobilized by the twist of the main chain conformation, and the ability to form a low pretilt angle could be exhibited. This presumption does not limit this disclosure in any way.

<Other ingredients>
The liquid crystal alignment agent of the present disclosure may contain other components other than the polymer (A), if necessary.

(Other polymers)
The liquid crystal alignment agent of the present disclosure contains a polymer (A) and a polymer having no structural unit (M1) (hereinafter, also referred to as "other polymer") as a polymer component. May be good. The other polymer is not particularly limited, but at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide and polyurea from the viewpoint of liquid crystal orientation, electrical characteristics, and mechanical strength of the obtained liquid crystal alignment film. (Hereinafter, also referred to as “polymer (B)”) can be preferably used. The polymer (B) is more preferably at least one selected from the group consisting of polyamic acids, polyamic acid esters and polyimides.

The blending ratio of the polymer (B) is 100 parts by mass of the polymer (A) used for preparing the liquid crystal aligning agent from the viewpoint of sufficiently obtaining the effect of improving the reduction of the pretilt angle by blending the polymer (A). On the other hand, it is preferably 100 to 2000 parts by mass, and more preferably 200 to 1500 parts by mass. As the polymer (B), one type may be used alone, or two or more types may be used in combination.
The polystyrene-equivalent weight average molecular weight (Mw) of the polymer (B) measured by GPC is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. The molecular weight distribution (Mw / Mn) is preferably 7 or less, more preferably 5 or less.

(Crosslinking agent)
The liquid crystal alignment agent of the present disclosure may contain a cross-linking agent. By blending the cross-linking agent with the liquid crystal alignment agent, the effect of lowering the pre-tilt angle can be further enhanced, which is preferable. The cross-linking agent is preferably a compound having a functional group capable of reacting with the functional group (for example, amino group, carboxyl group, etc.) of the polymer (A), and specifically, a cyclic ether group, a carboxyl group, etc. A compound having a molecular weight of 1000 or less and having at least one selected from the group consisting of a cyclic carbonate group, an alcoholic hydroxyl group, an amino group, a protected amino group, a protected isocyanate group, a trialkoxysilyl group, and a polymerizable unsaturated bond group. preferable. Of these, compounds having two or more epoxy groups can be particularly preferably used. The number of crosslinkable groups contained in the crosslinking agent is preferably 2 or more, and more preferably 3 or more.

When the cross-linking agent is blended, the content ratio of the cross-linking agent in the liquid crystal alignment agent is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the total amount of the polymer component in the liquid crystal alignment agent, and 1 mass by mass. More preferably, it is more than one part. Further, the content ratio of the cross-linking agent is preferably 30 parts by mass or less with respect to 100 parts by mass of the total amount of the polymer component in the liquid crystal alignment agent from the viewpoint of suppressing the performance deterioration due to the addition of an excessive amount. , 20 parts by mass or less is more preferable. As the cross-linking agent, one type can be used alone or two or more types can be used in combination.

(solvent)
The liquid crystal alignment agent of the present disclosure is prepared as a solution-like composition in which a polymer component and, if necessary, a component arbitrarily blended are preferably dissolved in an organic solvent. Examples of the organic solvent used include aprotonic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons and the like. The solvent component may be one of these or a mixed solvent of two or more.

As the solvent component, a solvent having high solubility and leveling property of the polymer (hereinafter, also referred to as “first solvent”), a solvent having good wettability and spreading property (hereinafter, also referred to as “second solvent”), and a solvent component. Examples thereof include these mixed solvents.
Specific examples of the solvent include, for example, N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4-methyl as the first solvent. -2-Pentanone, diisobutylketone, ethylene carbonate, propylene carbonate, N-ethyl-2-pyrrolidone, N- (n-pentyl) -2-pyrrolidone, N- (t-butyl) -2-pyrrolidone, N-methoxypropyl -2-Pyrrolidone, 1,3-dimethyl-2-imidazolidinone, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, etc.;
As the second solvent, for example, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diacetone alcohol, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, propylene glycol monomethyl Ether, propylene glycol monomethyl ether acetate, 3-methoxy-1-butanol, cyclopentanone, butyl lactate, butyl acetate, methylmethoxypropionate, ethylethoxypropionate, isoamylpropionate, isoamylisobutyrate, Examples thereof include propylene glycol diacetate, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, diisopentyl ether and the like. Of these, it is preferable to use a mixed solvent of the first solvent and the second solvent.

In addition to the above, other components contained in the liquid crystal alignment agent include, for example, functional silane compounds, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers and the like. Can be mentioned. The blending ratio of the other components can be appropriately selected according to each compound as long as the effects of the present disclosure are not impaired.

The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected in consideration of viscosity, volatility, etc., but is preferable. It is in the range of 1 to 10% by mass. When the solid content concentration is 1% by mass or more, a coating film having a sufficient film thickness can be obtained, and a good liquid crystal alignment film can be easily obtained. On the other hand, when the solid content concentration is 10% by mass or less, the film thickness of the coating film does not become excessive, the viscosity of the liquid crystal alignment agent can be made appropriate, and the deterioration of coatability can be suppressed. It is suitable in that it can be used.

≪Liquid crystal alignment film and liquid crystal element≫
The liquid crystal alignment film of the present disclosure is formed by the liquid crystal alignment agent prepared as described above. Further, the liquid crystal element of the present disclosure includes a liquid crystal alignment film formed by using the liquid crystal alignment agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and for example, TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe). It can be applied to various modes such as Field Switching) type, OCB (Optically Compensated Bend) type, and PSA type (Polymer Sustained Alignment). The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, the substrate used differs depending on the desired operation mode. Steps 2 and 3 are common to each operation mode.

<Step 1: Formation of coating film>
First, a liquid crystal alignment agent is applied onto the substrate, and preferably the coated surface is heated to form a coating film on the substrate. As the substrate, for example, glass such as float glass and soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (aliphatic olefin) can be used. As the transparent conductive film provided on one surface of a substrate, NESA film (US PPG registered trademark) made of tin oxide (SnO _2), indium oxide - such as an ITO film made of tin oxide _{(In 2} O 3 -SnO ₂₎ the Can be used. When manufacturing a TN type, STN type or VA type liquid crystal element, two substrates provided with a patterned transparent conductive film are used. On the other hand, in the case of manufacturing an IPS type or FFS type liquid crystal element, a substrate provided with electrodes patterned in a comb-teeth shape and a counter substrate not provided with electrodes are used. The liquid crystal alignment agent is applied to the substrate on the electrode forming surface, preferably by an offset printing method, a flexographic printing method, a spin coating method, a roll coater method, or an inkjet printing method.

After applying the liquid crystal alignment agent, preheating is preferably performed for the purpose of preventing the applied liquid crystal alignment agent from dripping. The pre-baking temperature is preferably 30 to 200 ° C., and the pre-baking time is preferably 0.25 to 10 minutes. After that, a firing (post-baking) step is carried out for the purpose of completely removing the solvent. The firing temperature (post-baking temperature) at this time is preferably 80 to 250 ° C, more preferably 80 to 200 ° C. The post-bake time is preferably 5 to 200 minutes. The film thickness of the film thus formed is preferably 0.001 to 1 μm.

<Step 2: Orientation treatment>
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal element, a treatment (alignment treatment) for imparting a liquid crystal alignment ability to the coating film formed in the above step 1 is performed. As a result, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film. In the case of manufacturing a vertically oriented liquid crystal element, the coating film formed in the above step 1 can be used as it is as a liquid crystal alignment film, but in order to further enhance the liquid crystal alignment ability, the coating film is oriented. It is good to apply. As the alignment treatment, it is preferable to use a photo-alignment treatment in which the coating film formed on the substrate is irradiated with light to impart the liquid crystal alignment ability to the coating film.

The light irradiation for photo-orientation includes a method of irradiating the coating film after the post-baking process, a method of irradiating the coating film after the pre-baking process and before the post-baking process, a pre-baking process and a post-baking process. It can be carried out by a method of irradiating the coating film while heating the coating film in at least one of them. As the radiation to irradiate the coating film, for example, ultraviolet rays including light having a wavelength of 150 to 800 nm and visible light can be used. Preferably, it is ultraviolet light containing light having a wavelength of 200 to 400 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation used is linearly polarized light or partially polarized light, the irradiation may be performed from a direction perpendicular to the substrate surface, may be performed from an oblique direction, or may be performed in combination thereof. In the case of unpolarized radiation, the irradiation direction is diagonal.

Examples of the light source used include a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, and the like. The irradiation amount of radiation is preferably 400 to 50,000 J / m ² , and more preferably 1,000 to 20,000 J / m ² . After light irradiation for imparting orientation ability, the surface of the substrate is washed with, for example, water, an organic solvent (for example, methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.) or a mixture thereof. Or a process of heating the substrate may be performed.

<Step 3: Construction of liquid crystal cell>
A liquid crystal cell is manufactured by preparing two substrates on which the liquid crystal alignment film is formed as described above and arranging the liquid crystal between the two substrates arranged opposite to each other. In order to manufacture a liquid crystal cell, for example, two substrates are arranged to face each other with a gap so that the liquid crystal alignment films face each other, and the peripheral portions of the two substrates are bonded to each other using a sealant to be attached to the substrate surface. Examples thereof include a method of injecting and filling a liquid crystal in a cell gap surrounded by a sealing agent to seal the injection hole, a method of using the ODF method, and the like. As the sealing agent, for example, an epoxy resin containing an aluminum oxide sphere as a curing agent and a spacer can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal, and among them, the nematic liquid crystal is preferable. In the PSA mode, after the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates.

Subsequently, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell to form a liquid crystal element. Examples of the polarizing plate include a polarizing plate in which a polarizing film called "H film" in which polyvinyl alcohol is stretch-oriented and iodine is absorbed is sandwiched between a cellulose acetate protective film, or a polarizing plate made of the H film itself.

The liquid crystal elements of the present disclosure can be effectively applied to various applications, for example, clocks, portable game machines, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, and various types. It can be applied to various display devices such as monitors, LCD TVs, and information displays, dimming films, retardation films, and the like.

Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the present disclosure is not limited to these Examples.

In the following example, the solution viscosity of the polymer solution and the imidization rate of the polyimide were measured by the following methods.
[Solution viscosity of polymer solution]
The solution viscosity (mPa · s) of the polymer solution was measured at 25 ° C. using an E-type rotational viscometer.
[Imidization rate of polyimide]
After the imidized polymer is dried under reduced pressure at room temperature, it is dissolved in deuterated dimethyl sulfoxide, ^{1 1} H-NMR is measured at room temperature using tetramethylsilane as a reference substance, and the formula shown by the following formula (I) is used. I asked.
Imidization rate (%) = (1-A ¹ / A ² x α) x 100 ... (I)
(In formula (I), A ¹ is the peak area derived from the proton of the NH group appearing near the chemical shift of 10 ppm, A ² is the peak area derived from other protons, and α is the precursor of the polymer (polyamic acid). ) Is the ratio of the number of other protons to one proton of the NH group.)

The compounds used in the examples are shown below. In the following, the compound represented by the formula (X) may be simply abbreviated as "compound (X)".

1. 1. Synthesis of compounds [Synthesis Example 1-1]
Compound (M-7) was synthesized according to Scheme 1 below.

10.0 g of trimellitic acid chloride and 100 ml of dehydrated tetrahydrofuran were added to a 500 ml eggplant flask containing a stirrer, and the mixture was cooled to 5 ° C. or lower in an ice bath (this is referred to as mixed solution A). Next, in another 500 ml eggplant flask containing a stir bar, 3,3,3', 3'-tetramethyl-2,2', 3,3'-tetrahydro-1,1'-spirobi [indene]- 14.6 g of 6,6'-diol (Organic Letters 6, 2341-2343, (2004)), 3.8 g of pyridine, and 100 ml of dehydrated tetrahydrofuran were added and mixed well to prepare a mixed solution B. The obtained mixed solution B was added dropwise to the mixed solution A over 2 hours while maintaining an internal temperature of 10 ° C. or lower. After completion of the dropping, the reaction was carried out at 5 ° C. or lower for 2 hours, slowly raised to room temperature, and then for 6 hours. Then, 100 ml of ethyl acetate, 100 ml of THF, and 100 ml of pure water were added to the reaction solution, and liquid separation extraction was performed. Subsequently, a washing operation of adding 100 ml of pure water to the organic layer and separating and extracting the liquid was carried out twice. The organic layer was recovered and concentrated by an evaporator to obtain a solid.
80 ml of acetic acid and 20 ml of acetic anhydride were added to the precipitated solid, and the mixture was refluxed at 110 ° C. for 3 hours. The crystals obtained by slowly cooling to room temperature were filtered and washed with hexane. After vacuum drying, 8.2 g of the target compound (M-7) was obtained.

[Synthesis Example 1-2]
Compound (M-8) was synthesized according to Scheme 2 below.

-Synthesis of Intermediate A 5,5'-diamino-3,3,3', 3'-tetramethyl-2,2', 3,3'-tetrahydro-1 in a 2000 mL three-necked flask containing a stir bar , 1'-Supirobi [Inden] -6,6'-diol (Bulletin of the Korean Chemical Society, 34, 12, 3888-3890 (2013)) 20.0 g, 1000 g of tetrahydrofuran was taken, 9.0 g of triethylamine was added, and I took an ice bath. A solution consisting of 14.2 g of t-butyl dicarbonate and 150 g of tetrahydrofuran was added dropwise thereto, and the mixture was stirred at room temperature for 10 hours, 450 g of ethyl acetate was added to the reaction solution, and the mixture was washed four times with 300 g of distilled water. Then, the organic layer was slowly concentrated by a rotary evaporator until the content reached 100 g, and the white solid precipitated on the way was recovered by filtration. The white solid was vacuum dried to obtain 30.2 g of compound (Intermediate A).
-Synthesis of intermediate B 30.0 g of (E) -3-(4-((4- (4,4,4-trifluorobutoxy) benzoyl) oxy) phenyl) acrylic acid in a 500 mL eggplant flask containing a stirrer. , 90 g of thionyl chloride and 0.02 g of N, N-dimethylformamide were added, and the mixture was stirred at 80 ° C. for 1 hour. Then, excess thionyl chloride was removed with a diaphragm pump, and 300 g of tetrahydrofuran was added to prepare a solution D.
20.49 g of Intermediate A, 400 g of tetrahydrofuran, and 12.1 g of pyridine were newly added to a 2000 mL three-necked flask containing a stirrer, and the mixture was ice-cooled. Solution D was added dropwise thereto, and the mixture was stirred at room temperature for 3 hours. The reaction solution was reprecipitated with 7 L of water, and the obtained white solid was vacuum dried to obtain 29.5 g of Intermediate B.
-Synthesis of compound (M-8) 25.0 g of compound (intermediate B) and 6.0 g of trifluoroacetic acid were taken in a 500 mL eggplant flask containing a stirrer, 200 g of dichloromethane was added, and the mixture was stirred at room temperature for 1 hour. Then, after neutralizing with saturated aqueous sodium hydrogen carbonate solution, it was washed four times with 100 g of distilled water. Then, the organic layer was slowly concentrated by a rotary evaporator until the content reached 50 g, and the white solid precipitated on the way was recovered by filtration. The white solid was vacuum dried to obtain 23.0 g of the target compound (M-8).

Compounds (M-1) to (M-6), (M-9) and (M-10) were synthesized according to the methods described in the following documents.
Compound (M-1): US Pat. No. 5,216,173 Compound (M-2): Bulletin of the Chemical Society of Japan, 72,5,1075-1081 (1999)
Compound (M-3): Journal of the Chemical Society, 121,1644 (1922)
Compound (M-4): Justus Liebigs Annalen der Chemie, 593, 1-17 (1955)
Compound (M-5): Bulletin of the Chemical Society of Japan, 44,496-505 (1971)
Compound (M-6): US Patent Application Publication No. 2018/371168 Compound (M-9): Taiwan Patent Application Publication No. 2017/31851 Compound (M-10): Journal of Materials Chemistry, 7, 4,589-592 (1997)

2. 2. Synthesis of polymer [Synthesis Example 2-1]
A polymer (PA-1) is obtained by dissolving 50 parts by mol of compound (M-1) and 50 parts by mole of compound (M-11) in N-methyl-2-pyrrolidone (NMP) and reacting at 40 ° C. for 24 hours. ) Was obtained in an amount of 20% by mass. A small amount of this solution was taken, γ-butyrolactone was added, and the solution was measured as a solution having a concentration of 10% by mass. The solution viscosity was 28 mPa · s.
[Synthesis Examples 2-2-2-4, 2-7-2-15, 2-17 and 2-18]
Polymers (PA-2) to (PA) can be obtained by performing the same operations as in Synthesis Example 2-1 except that the types and amounts of the acid dianhydride and diamine compounds used are changed as shown in Table 1 below. -4), (PA-7) to (PA-14), (PR-1), (PR-3), and (PR-4) were obtained in 10% by mass, respectively.

[Synthesis Example 2-5]
50 mol parts of compound (M-4) and 50 mol parts of compound (M-11) were dissolved in NMP and reacted at 40 ° C. for 24 hours to obtain a solution containing 20% by mass of polyamic acid. Next, NMP was added to the obtained polyamic acid solution to prepare a solution having a concentration of 10% by mass, and 300 mol parts of pyridine and 300 mol parts of acetic anhydride were added to carry out a dehydration ring closure reaction at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system is replaced with a new γ-butyrolactone, and the mixture is further concentrated to obtain a polyimide having an imidization rate of about 50% (this is referred to as “polymer (PA-5)”). Was obtained in an amount of 20% by mass. A small amount of this solution was taken, γ-butyrolactone was added, and the solution was measured as a solution having a concentration of 10% by mass. The solution viscosity was 37 mPa · s.

[Synthesis Example 2-6]
By performing the same operation as in Synthesis Example 2-5 except that 50 parts by mole of compound (M-4) and 25 parts by mole of compound (M-11) were used as the monomers, a polyimide having an imidization ratio of about 50% was contained. Obtained a solution. Next, 25 mol parts of the compound (M-14) was added to the reaction solution to dissolve it, and the mixture was reacted at 40 ° C. for 24 hours to obtain a solution containing 10% by mass of the polymer (PA-6). A small amount of this solution was taken, γ-butyrolactone was added, and the solution was measured as a solution having a concentration of 10% by mass. The solution viscosity was 31 mPa · s.
[Synthesis Example 2-16]
By performing the same operation as in Synthesis Example 2-5 except that the types and amounts of acid anhydrides and diamines used were changed as shown in Table 1 below, a polyimide having an imidization ratio of about 50% was used. A solution containing 20% by mass of "polymer (PR-2)" was obtained.

In Table 1, the numerical values of the acid dianhydride and the diamine compound represent the ratio (mol%) of each compound to the total amount of the monomers used in the synthesis of each polymer.

[Synthesis Example 2-19]
100 parts of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CB) and 100 parts of 2,2'-dimethyl-4,4'-diaminobiphenyl (mTB) in N-methyl-2- It was dissolved in pyrrolidone (NMP) and reacted at room temperature for 6 hours to obtain a solution containing 10% by mass of the polymer (PAA-A).
[Synthesis Example 2-20]
100 mol parts of 2,3,5-tricarboxycyclopentylacetic acid dianhydride (TCA) and N4, N4'-bis- (4-aminophenyl) -N4, N4'-dimethylbiphenyl-4,4'-diamine ( A solution containing 10% by mass of the polymer (PAA-B) was obtained by dissolving 30 parts by mol of DABzM) and 70 parts by mol of diaminodiphenylmethane (DDM) in NMP and reacting at 60 ° C. for 6 hours.
[Synthesis Example 2-21]
1,2,3,4-Cyclobutanetetracarboxylic dianhydride (CB) 100 mol parts, 4,4'-[4,4'-propane-1,3-diylbis (piperidin-1,4-diyl)] 30 parts by mole of dianiline (BISP) and 70 parts by mole of 4,4'-diaminodiphenylmethane (DDM) are dissolved in NMP and reacted at 60 ° C. for 6 hours to contain 10% by mass of the polymer (PAA-C). A solution was obtained.

[Example 1]
(1) Preparation of liquid crystal aligning agent In the solution containing the polymer (PAA-A) obtained in Synthesis Example 2-17, the solution containing the polymer (PA-1) obtained in Synthesis Example 2-1 and the solution containing the polymer (PA-1). NMP and butyl cellosolve (BC) are added as a solvent, the polymer ratio is polymer (PAA-A): polymer (PA-1) = 80: 20 (mass ratio), and the solvent composition is NMP / BC = 50/50 (mass ratio). A solution having a solid content concentration of 3.5% by mass was prepared. A liquid crystal alignment agent (AL-1) was prepared by filtering this solution through a filter having a pore size of 1 μm.

(2) Manufacture of Optical Vertical Liquid Crystal Display Element The liquid crystal alignment agent (AL-1) prepared in (1) above is applied on the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film by a spinner, and the temperature is 80 ° C. Prebaking was performed for 1 minute on the hot plate of No. 1 to form a coating film having a film thickness of 0.08 μm. Next, the surface of the coating film was irradiated with polarized ultraviolet rays of 200 J / m ² containing a bright line of 313 nm at room temperature from a direction inclined by 40 ° from the normal of the substrate by using an Hg-Xe lamp and a Gran Tailor prism. Next, the inside of the oven was heated (mainly fired) at 160 ° C. for 40 minutes in a nitrogen-substituted oven to obtain a liquid crystal alignment film. The same operation was repeated to prepare a pair (two) of substrates on which the liquid crystal alignment film was formed.
A pair of epoxy resin adhesives containing aluminum oxide spheres having a diameter of 3.5 μm are applied by screen printing to the outer periphery of the surface having the liquid crystal alignment film on one of the two substrates on which the liquid crystal alignment film is formed. The liquid crystal alignment film surfaces of the substrates are opposed to each other, and the pair of substrates are crimped so that the projection directions of the optical axes of the ultraviolet rays radiated to each substrate are opposite to each other, and the adhesive is applied at 150 ° C. for 1 hour. It was heat-cured. Next, a nematic liquid crystal (MLC-6608, manufactured by Merck Co., Ltd.) was filled in the gap between the substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive to obtain a liquid crystal cell. Further, in order to eliminate the flow orientation at the time of liquid crystal injection, the liquid crystal cell was heated at 150 ° C. and then slowly cooled to room temperature. Next, polarizing plates are placed on both outer surfaces of the substrate in the liquid crystal cell so that their polarization directions are orthogonal to each other and the optical axis of the ultraviolet rays irradiated at the time of forming the liquid crystal alignment film is projected at an angle of 45 ° to the substrate surface. I stuck them together.

(3) Evaluation of pre-tilt angle The liquid crystal display element manufactured in (2) above conforms to the method described in the non-patent document (TJ Scheffer et. Al. J. Appl. Phys. Vo. 19. p2013 (1980)). Then, the value of the tilt angle of the liquid crystal molecules from the substrate surface measured by the crystal rotation method using He-Ne laser light was defined as the pretilt angle. At this time, when the pre-tilt angle is 88.0 degrees or less, it is "good (◎)", when it is larger than 88.0 degrees and less than 89.0 degrees, it is "possible (○)", and when it is 89.0 degrees or more. Was marked as "defective (x)". As a result, in this example, the evaluation was "OK (○)".

(4) Evaluation of coating uniformity The liquid crystal alignment agent (AL-1) prepared in the above (1) is coated on a glass substrate using a spinner, prebaked on a hot plate at 80 ° C. for 1 minute, and then prebaked. A coating film having an average film thickness of 0.1 μm was formed by heating (post-baking) the inside of the chamber in a nitrogen-substituted oven at 200 ° C. for 1 hour. The surface of the obtained coating film was observed with an atomic force microscope (AFM), and the uniformity of the coating film surface was evaluated by measuring the center average roughness (Ra). When Ra was 5 nm or less, the coating uniformity was evaluated as “good (◯)”, when it was larger than 5 nm and less than 10 nm, it was evaluated as “possible (Δ)”, and when it was 10 nm or more, it was evaluated as “poor (×)”. As a result, in this example, the evaluation was "good (○)".

[Examples 2 to 15, Comparative Examples 1 to 4]
The liquid crystal alignment agents were prepared in the same manner as in Example 1 except that the formulation of the liquid crystal alignment agent was changed as shown in Table 2 below. Further, using each of the prepared liquid crystal alignment agents, an optical vertical liquid crystal display element was manufactured in the same manner as in Example 1, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 2 below. In Examples 2 and 5, an additive was added to the liquid crystal alignment agent by 5 parts by mass with respect to 100 parts by mass of the total amount of the polymer components.

In Table 2, the "blend ratio" represents the blending ratio (mass ratio) of the polymer 1 and the polymer 2. Abbreviations for additives represent the following compounds.
Add-A: Compound represented by the following formula (Add-A) Add-B: Compound represented by the following formula (Add-B)

As shown in Table 2 above, in Examples 1 to 15 in which the liquid crystal aligning agent containing the polymer (A) was used, the pretilt angle was less than 89 degrees, and Comparative Examples 1 to 4 containing no polymer (A). In comparison with the above, the tilt angle of the liquid crystal molecules from the vertical direction could be made sufficiently large. Since the liquid crystal alignment agent of Comparative Example 4 did not show photoalignment, it was indicated as "-" in the column for evaluating the pretilt angle.
In addition, the liquid crystal alignment agents of Examples 1 to 15 were evaluated as "good" or "possible" in terms of coatability on the substrate.
In particular, in Example 5 in which the cross-linking agent was blended and Examples 6 and 7 in which the polyimide (A) was used, the pretilt angle evaluation was "good (⊚)" and the coatability of the liquid crystal alignment agent was also "good (◎). ○) ”, which was particularly excellent. Further, also in Example 14 using the polymer (PA-13) and Example 15 using the polymer (PA-14), the pre-tilt angle evaluation was “good (⊚)” and the liquid crystal alignment agent was easy to apply. It was "good (○)" and was particularly excellent.
From the above results, it was found that by preparing the liquid crystal alignment agent using the polymer (A), it is possible to form a liquid crystal alignment film having excellent pretilt angle characteristics while maintaining good coatability on the substrate.

Claims (12)

1. A liquid crystal aligning agent containing a polymer (A) having a structural unit (M1) derived from a monomer having a spiro ring and having a photo-oriented group.
2. The liquid crystal alignment agent according to claim 1, wherein the polymer (A) is at least one selected from the group consisting of polyamic acid, polyimide, polyamic acid ester, polyenamine and polyamide.
3. The liquid crystal alignment agent according to claim 1 or 2, wherein the structural unit (M1) contains a structural unit derived from an acid dianhydride having a spiro ring.
4. The liquid crystal alignment agent according to any one of claims 1 to 3, wherein the structural unit (M1) contains a structural unit derived from a diamine having a spiro ring.
5. The liquid crystal aligning agent according to any one of claims 1 to 4, wherein the polymer (A) further has a structural unit (M2) having no spiro ring and having a photo-oriented group.
6. The liquid crystal alignment agent according to any one of claims 1 to 5, wherein the structural unit (M1) has a photo-oriented group.
7. Claims 1 to 6, further comprising a polymer (B) which is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide and polyurea and does not have the structural unit (M1). The liquid crystal alignment agent according to any one item.
8. A liquid crystal alignment film formed by using the liquid crystal alignment agent according to any one of claims 1 to 7.
9. A liquid crystal element provided with the liquid crystal alignment film according to claim 8.
10. A polymer having a structural unit having a spiro ring and having a photo-oriented group.
11. A compound represented by the following formula (6).
    

    

    (In formula (6), Y ¹ to Y ⁴ are independently single bonds, oxygen atoms, or alkanediyl groups having 1 to 10 carbon atoms. However, ^one of Y ¹ and Y ² is an oxygen atom. Or, in the case of a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms, and when one of Y ³ and Y ⁴ is an oxygen atom or a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms. . X ² and X ³ are independent oxygen atoms, sulfur atoms, -COO-, -OCO-, -NHCO- or -CONH-. R ¹ to R ⁴ are independent carbon atoms, respectively. It is an alkyl group having the number 1 to 5, an alkoxy group having 1 to 5 carbon atoms, a phenyl group, a halogen atom or a hydroxyl group. N1 and n2 are 0 or 1, respectively. T1 to t4 are independent, respectively. It is an integer of 0 to 2. When a plurality of R ¹ to R ⁴ are present in the formula, the plurality of groups are the same group or different groups.)
12. A compound represented by the following formula (7A).
    

    

    (In the formula (7A), Y ⁵ to Y ⁸ are independently single bonds, oxygen atoms, or alkanediyl groups having 1 to 10 carbon atoms. However, one of Y ⁵ and Y ⁶ is an oxygen atom. Or, in the case of a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms, and when one of Y ⁷ and Y ⁸ is an oxygen atom or a single bond, the other is an alkanediyl group having 1 to 10 carbon atoms. . X ⁴ and X ⁵ are independently oxygen atoms, sulfur atoms, -COO-, -OCO-, -NHCO- or -CONH-. R ⁵ and R ⁶ are independent carbons, respectively. It is an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a phenyl group, a halogen atom or a hydroxyl group. R ¹⁷ is an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and phenyl. A group, a monovalent group having a photo-oriented group, a halogen atom or a hydroxyl group. R ¹⁸ is a monovalent group having a photo-oriented group. N3 and n4 are independently 0 or 1, respectively. there .t5 ~ t8 are each independently an integer of ^{0 ~ 2 .R 5, R 6} , R 17 and ^{R 18,} when a plurality present in the formula, the plurality of groups same group or different groups Is.)