JP2019211777A - Liquid crystal aligning agent for photo-alignment, liquid crystal alignment film and liquid crystal display element using the same - Google Patents

Abstract

To provide a liquid crystal alignment film having high stability to light and achieving a higher contrast when applied to a liquid crystal display element, and a liquid crystal aligning agent that allows formation of the above liquid crystal alignment film.SOLUTION: A liquid crystal aligning agent for photo-alignment is provided, which contains a polymer component that has a structural unit including a photoreactive structure. The polymer component comprises a polymer or its derivative obtained by polymerizing a monomer composition containing at least a first monomer and a second monomer. The first monomer includes a photoreactive structure in a moiety forming the structural unit of the polymer, in which the moiety forming the structural unit of the polymer induces a chemical reaction by heating. The second monomer includes a photoreactive structure in a moiety forming the structural unit of the polymer, in which the moiety forming the structural unit of the polymer does not induce a chemical reaction by heating.SELECTED DRAWING: None

Description

  The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element using the same. Specifically, a liquid crystal alignment agent for forming a photo-alignment liquid crystal alignment film (hereinafter sometimes referred to as a photo-alignment film), and a photo-alignment liquid crystal alignment film formed using the liquid crystal alignment agent The present invention also relates to a liquid crystal display element having the liquid crystal alignment film.

  TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, IPS (In-Plane Switching) mode, FFS (Fringe Field Switching) mode, vertical alignment type VA (Multi-domain Vertical Alignment) mode Various drive systems are known. These liquid crystal display elements are applied to image display devices of various electronic devices such as televisions and mobile phones, and are being developed with the aim of further improving display quality. Specifically, the improvement of the performance of the liquid crystal display element is achieved not only by the improvement of the driving system and the element structure, but also by the constituent members used for the element. Among the constituent members used for the liquid crystal display element, the liquid crystal alignment film is one of important members relating to the display quality, and this liquid crystal alignment film is required to meet the demand for higher quality of the liquid crystal display element. There is a lot of research going on.

Here, the liquid crystal alignment film is provided on and in contact with the liquid crystal layer on a pair of substrates provided on both sides of the liquid crystal layer of the liquid crystal display element, and the liquid crystal molecules constituting the liquid crystal layer are fixed to the substrate. It has a function of aligning with regularity. By using a liquid crystal alignment film having high liquid crystal alignment properties, a liquid crystal display element with high contrast and improved afterimage characteristics can be realized (see, for example, Patent Documents 1 and 2).
For the formation of such a liquid crystal alignment film, at present, a solution (varnish) in which polyamic acid, soluble polyimide or polyamic acid ester is dissolved in an organic solvent is mainly used. In order to form a liquid crystal alignment film with these varnishes, after applying the varnish to the substrate, the coating film is solidified by heating or the like to form a polyimide-based liquid crystal alignment film, and an alignment suitable for the above-described display mode as necessary. Apply processing. The alignment treatment method includes rubbing that rubs the surface of the alignment film with a cloth to align the direction of the polymer molecule, and irradiation of the alignment film with linearly polarized ultraviolet rays, thereby photoisomerization and dimerization of the polymer molecule. A photo-alignment method that causes photochemical changes and imparts anisotropy to the film is known. Among them, the photo-alignment method has higher uniformity of alignment than the rubbing method, and a non-contact alignment method. Therefore, there are advantages such that the film is not damaged and the cause of the display failure of the liquid crystal display element such as dust generation or static electricity can be reduced.

  As a liquid crystal alignment film using such a photo-alignment method, for example, Patent Documents 1 to 5 obtain a photo-alignment film having a large anchoring energy and good liquid crystal alignment by applying a photoisomerization technique. It is described.

JP 2010-197999 A International Publication No. 2013/157463 JP 2005-275364 A JP 2007-248637 A JP 2009-0669493 A JP 11-249142 A International Publication No. 2013/161569 JP2015-135464A International Publication No. 2017/119376

As described above, a polyimide-based liquid crystal alignment film is known which has been subjected to an alignment process by a photo-alignment method to impart anisotropy. However, the polyimide-based liquid crystal alignment film by the photo-alignment method is generally inferior to the polyimide-based liquid crystal alignment film by the rubbing process, and in particular, in a usage situation where light from the backlight is irradiated for a long time, There is a tendency that the display quality of the liquid crystal display element tends to be impaired. This is because the specific site (photoreactive group) introduced into the liquid crystal alignment film to cause a photochemical reaction, especially the azo group absorbs light and tends to generate radicals. This is probably because the retention rate (hereinafter abbreviated as VHR) decreases.
In response to this, studies have been made to suppress the decrease in the voltage holding ratio of the liquid crystal display element by devising the layer structure and the like while using the polyimide-based liquid crystal alignment film by the conventional photo-alignment method (for example, And see Patent Documents 6 to 9.). However, even if such a configuration is adopted for the liquid crystal alignment film, as long as the liquid crystal alignment film has a photoreactive group, a decrease in the voltage holding ratio due to the photodegradation is inevitable, which is sufficient for recent demands. The reality is that it is difficult to achieve display quality that meets the requirements.

  Therefore, the present inventors, when applied to a liquid crystal display element, have a new liquid crystal alignment that is unlikely to cause a decrease in voltage holding ratio due to light irradiation and that realizes a high contrast and a clear light-dark display that meets recent requirements. Studies were carried out to find the composition of the membrane. As a result, for the problem of a decrease in voltage holding ratio, a substituent that chemically reacts with the photoreactive group is introduced into the polymer of the liquid crystal alignment film, and the photoreactive group reacts with the substituent by heating. It has been found that the deterioration of electrical characteristics accompanying light irradiation is remarkably suppressed by converting into a structure having high light stability.

  In Patent Documents 6 to 9, in order to suppress the decrease in the voltage holding ratio of the liquid crystal display element, the device is focused on the configuration of the liquid crystal alignment film. There is no mention of introducing a structure that reacts to a photoreactive group into a light-stable structure by a chemical reaction by heating. From these documents, such a structure is not described. It is unpredictable that the reduction in the voltage holding ratio of the liquid crystal display element is suppressed by the introduction.

  Under such circumstances, the present inventors have proposed a liquid crystal alignment film that has high stability to light and that realizes higher contrast when applied to a liquid crystal display element, and such a liquid crystal alignment film. In order to provide a liquid crystal aligning agent that can be formed, intensive studies were advanced. In addition, intensive studies have been conducted for the purpose of providing a liquid crystal display element that maintains a high voltage holding ratio even when exposed to light from a backlight or the like for a long time, has a high contrast, and has a bright and dark display.

  As a result of intensive studies to solve the above problems, the present inventors have a photoreactive structure and a first monomer that causes a chemical reaction by heating and a photoreactive structure. In the liquid crystal display element to which the liquid crystal alignment film is applied by forming a liquid crystal alignment film using a polymer component synthesized by using a second monomer that does not cause a chemical reaction by heating as a liquid crystal alignment agent, It has been found that the decrease in the voltage holding ratio due to light irradiation is remarkably suppressed, and that the contrast is high and clear bright and dark display is realized. The present invention has been proposed based on such knowledge, and specifically has the following configuration.

[1] A liquid crystal aligning agent for photo-alignment containing a polymer component having a structural unit containing a photoreactive structure, wherein the polymer component is a monomer composition containing at least a first monomer and a second monomer. A polymer obtained by polymerization or a derivative thereof, wherein the first monomer includes a photoreactive structure in a portion forming a structural unit of the polymer, and a portion forming a structural unit of the polymer The second monomer has a photoreactive structure in a portion that forms the structural unit of the polymer, and a portion that forms the structural unit of the polymer is heated by heating. A liquid crystal aligning agent for photo-alignment, which has a structure that does not cause a chemical reaction.
[2] The liquid crystal aligning agent for photoalignment according to [1], wherein the chemical reaction in the first monomer is a cyclization reaction.
[3] The first monomer includes a photoreactive structure having at least one of a structure represented by the following formula (a-1) and a structure represented by the following formula (a-2). Or the liquid crystal aligning agent for photo-alignment as described in [2].

[In the formula (a-1), R ^a represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group. Represents;
In formula (a-2), R ^b and R ^c are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted group Or an unsubstituted arylcarbonyl group;
In formula (a-1) and formula (a-2), * represents a bonding position with a photoreactive group. ]
[4] The liquid crystal aligning agent for photoalignment according to any one of [1] to [3], wherein the first monomer includes a photoreactive structure having a photoisomerization structure or a photofleece rearrangement structure.
[5] The liquid crystal aligning agent for photoalignment according to any one of [1] to [4], wherein the first monomer includes a photoreactive structure having a structure represented by the following formula (1).

[In Formula (1), R ¹ and R ² each independently represent a hydrogen atom, a group represented by the following Formula (1-1) or the following Formula (1-2), and R ¹ and R ² Is at least one group represented by the following formula (1-1) or the following formula (1-2);
* Represents a bonding position on the benzene ring, and is either one of the positions that can be replaced with a hydrogen atom on one benzene ring or the position that can be replaced with a hydrogen atom on the other benzene ring;
The hydrogen atom of the benzene ring may be substituted with a substituent. ]

[In Formula (1-1) and Formula (1-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, substituted or unsubstituted Represents a substituted alkoxycarbonyl group or a substituted or unsubstituted arylcarbonyl group;
* Represents the bonding position to the benzene ring in formula (1). ]
[6] The polymer obtained by polymerizing the monomer composition or a derivative thereof is at least one selected from polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide,
The liquid crystal aligning agent for photo-alignment in any one of [1]-[5] whose said 1st monomer is diamine represented by following formula (2).

[In Formula (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by Formula (1-1) or Formula (1-2), and at least ^one of R ¹ and R ² One is a group represented by formula (1-1) or formula (1-2);
R ⁶ and R ⁸ are each independently a linear alkylene group having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, —CON (CH ₃ ) — or a single bond, and in R ⁶ and R ⁸ , one of —CH ₂ — in the linear alkylene group or two that are not adjacent to each other may be replaced by —O—;
R ⁷ and R ⁹ each independently represents a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, a heterocyclic ring, or a single bond;
The bonding position of H ₂ N—R ⁷ —R ⁶ — is one of the positions capable of substituting for a hydrogen atom in one benzene ring, and the bonding position of H ₂ N—R ⁹ —R ⁸ — is the other bonding position. Any of the possible substitution positions for a hydrogen atom in the benzene ring;
The hydrogen atom in the benzene ring may be substituted with a substituent. ]

[In Formula (1-1) and Formula (1-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, substituted or unsubstituted Represents a substituted alkoxycarbonyl group or a substituted or unsubstituted arylcarbonyl group;
* Represents the bonding position to the benzene ring in formula (2). ]
[7] The liquid crystal aligning agent for photo-alignment according to [5] or [6], wherein R ¹ is a group represented by formula (1-1) and R ² is a hydrogen atom.
[8] The liquid crystal aligning agent for photoalignment according to [7], wherein R ⁴ is a hydrogen atom or a substituted or unsubstituted alkyl group.
[9] The liquid crystal aligning agent for photo-alignment according to [6], wherein the diamine represented by the formula (2) is a diamine represented by any one of the following formulas (3) to (6).

[In the formulas (3) to (6), R ⁴ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or substituted or unsubstituted Represents an unsubstituted arylcarbonyl group;
The hydrogen atom of the benzene ring may be substituted with a substituent;
In Formula (5) and Formula (6), R ⁵ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or substituted or unsubstituted Represents an unsubstituted arylcarbonyl group. ]
[10] The diamine represented by the formula (2) is represented by the following formula (3-1) to formula (3-9), formula (4-1) to formula (4-9), formula (5-1). The liquid crystal aligning agent for photo-alignment according to [6] or [9], which is a diamine represented by any one of formula (5-2), formula (6-1), and formula (6-2).

[In the formula, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, ⁱ Pr represents an isopropyl group, Bu represents a butyl group, and ^t Bu represents a t-butyl group. ]
[11] The liquid crystal aligning agent for photoalignment according to any one of [1] to [10], wherein the second monomer includes a photoreactive structure having a photoisomerization structure or a photodimerization structure.
[12] The liquid crystal aligning agent for photoalignment according to [11], wherein the second monomer includes a photoreactive structure having a photoisomerization structure.
[13] The liquid crystal aligning agent for photo-alignment according to any one of [6] to [12], wherein the second monomer is a diamine.
[14] The liquid crystal aligning agent for photo-alignment according to any one of [6] to [13], wherein the monomer composition contains tetracarboxylic dianhydride.
[15] The amount of the first monomer in the monomer composition is 15 to 85 mol% with respect to the total number of moles of the first monomer and the second monomer. [1] to [14 ] The liquid crystal aligning agent for photo-alignment in any one of.
[16] The liquid crystal aligning agent further contains a second polymer component,
The second polymer component is for photo-alignment according to any one of [1] to [15], wherein the second polymer component is made of a polymer obtained by polymerizing a monomer composition comprising a monomer that does not contain a photoreactive structure or a derivative thereof. Liquid crystal aligning agent.
[17] The polymer obtained by polymerizing the monomer composition or a derivative thereof is at least one selected from polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide. 16]. The liquid crystal aligning agent for photo-alignment as described in 16].
[18] The liquid crystal aligning agent for photoalignment according to any one of [1] to [17], which is used for forming a liquid crystal alignment film of a horizontal electric field type liquid crystal display element.
[19] A liquid crystal alignment film formed of the liquid crystal aligning agent for photo alignment according to any one of [1] to [18].
[20] A liquid crystal display device having the liquid crystal alignment film according to [19].
[21] An alignment process for imparting anisotropy by irradiating polarized light to a film comprising the liquid crystal aligning agent for photo-alignment according to any one of [1] to [18], and the film provided with anisotropy A heating and firing step of heating and firing, and during the heating and firing step, the photoreactive structure of the polymer component contained in the liquid crystal aligning agent for photo-alignment causes a cyclization reaction to reduce photoreactive groups A method for forming a liquid crystal alignment film.
[22] The method for forming a liquid crystal alignment film according to [21], wherein the heating and baking step is performed in two or more steps by changing a heating temperature.
[23] A method for producing a liquid crystal display element, wherein the liquid crystal alignment film is formed using the method for forming a liquid crystal alignment film according to [21] or [22].
[24] The method for producing a liquid crystal display element according to [23], wherein the liquid crystal display element to be produced is a horizontal electric field type liquid crystal display element.
[25] A polyamic acid or a derivative thereof obtained by polymerizing a monomer composition containing a first monomer, a second monomer, and a non-photoreactive tetracarboxylic dianhydride,
The first monomer is a diamine represented by the following formula (2):
Said second monomer is represented by formula (II-1), formula (II-2), formula (III-1), formula (III-2), formula (IV-1), formula (IV-2), formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula ( VIII-1) and the polyamic acid or a derivative thereof which is a compound represented by any one of formulas (VIII-2).

[In Formula (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by Formula (1-1) or Formula (1-2), and at least ^one of R ¹ and R ² One is a group represented by formula (1-1) or formula (1-2);
R ⁶ and R ⁸ are each independently a linear alkylene group having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, —CON (CH ₃ ) — or a single bond, and in R ⁶ and R ⁸ , one of —CH ₂ — in the linear alkylene group or two that are not adjacent to each other may be replaced by —O—;
R ⁷ and R ⁹ each independently represents a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, a heterocyclic ring, or a single bond;
The bonding position of H ₂ N—R ⁷ —R ⁶ — is one of the positions capable of substituting for a hydrogen atom in one benzene ring, and the bonding position of H ₂ N—R ⁹ —R ⁸ — is the other bonding position. Any of the possible substitution positions for a hydrogen atom in the benzene ring;
The hydrogen atom in the benzene ring may be substituted with a substituent. ]

[In Formula (1-1) and Formula (1-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, substituted or unsubstituted Represents a substituted alkoxycarbonyl group or a substituted or unsubstituted arylcarbonyl group;
* Represents the bonding position to the benzene ring in formula (2). ]

(Formula (II-1), Formula (II-2), Formula (III-1), Formula (III-2), Formula (IV-1), Formula (IV-2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula (VIII-1), and In the formula (VIII-2), a group whose bonding position is not fixed to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary, and in the formula (IV-3), r Is an integer of 1 to 10, and in formula (V-2), R ⁶ independently represents —CH ₃ , —OCH ₃ , —CF ₃ , or —COOCH ₃ , and a independently represents 0 to 2 In formula (V-3), ring A and ring B are each independently selected from monocyclic hydrocarbons, condensed polycyclic hydrocarbons and heterocyclic rings. R ¹¹ represents at least one, and R ¹¹ represents a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, or —CON (CH ₃ )-and R ¹² represents a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, or —CON (CH ₃ )-, in R ¹¹ and R ¹² , one or two of the linear alkylene —CH ₂ — may be substituted with —O—, and R ^{7 to} R ¹⁰ are each independently -F, -CH _3, -OCH _3, represents -CF ₃ or -OH,, b to e are each independently an integer of 0 to 4, in formula (VII-1), R ⁴ and R ⁶ is independently straight-chain alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO. —, —CONH—, —N (CH ₃ ) CO—, —CON (CH ₃ ) —, or a single bond, in R ⁴ and R ⁶ , one or not of —CH ₂ — of the linear alkylene may be two replaced by -O-, R ⁵ and R ⁷ independently represent monocyclic hydrocarbon, fused polycyclic hydrocarbon, a heterocycle, or a single bond.)
[26] The second monomer is represented by the following formula (V-2-1), formula (V-3-2), formula (VI-2-1), formula (VII-1-1) and formula (VII- The polyamic acid or derivative thereof according to [25], which is a compound represented by any one of 1-2).

[27] The polyamic acid or derivative thereof according to [25] or [26], comprising at least one selected from polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide.

  By using the liquid crystal alignment film formed with the liquid crystal aligning agent for photo-alignment of the present invention, a decrease in voltage holding ratio accompanying light irradiation is suppressed, and a liquid crystal display element with high contrast and bright and dark display is realized. be able to.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

Liquid crystal aligning agent for photo-alignment The “liquid crystal aligning agent for photo-alignment” in the present invention means a liquid crystal aligning agent capable of imparting anisotropy by irradiating polarized light when the film is formed on a substrate. In the present specification, it may be simply referred to as “liquid crystal aligning agent”. The liquid crystal aligning agent (liquid crystal aligning agent) for photo-alignment of this invention is used for formation of a liquid crystal aligning film.
The liquid crystal aligning agent for photo-alignment of the present invention is a liquid crystal aligning agent for photo-alignment containing a polymer component having a constitutional unit containing a photoreactive structure, and the polymer component contains at least a first monomer and a second monomer It consists of a polymer obtained by polymerizing a monomer composition containing a monomer or a derivative thereof. Of the monomers contained in the monomer composition, the first monomer contains a photoreactive structure in the portion that forms the polymer structural unit, and the portion that forms the polymer structural unit undergoes a chemical reaction by heating. The second monomer has a photoreactive structure in the portion forming the polymer structural unit, and the portion forming the polymer structural unit does not cause a chemical reaction due to heating. It is.
The “photoreactive structure” in the present invention means an atomic group whose structure changes upon irradiation with light. Such a photoreactive structure usually has a specific site (photoreactive group) that absorbs light and causes a chemical change, and the structure changes due to the chemical change of the photoreactive group. In the following description, such a change in the photoreactive structure due to light irradiation is referred to as a photochemical change. Specific examples of the photochemical change include photoisomerization and photofries rearrangement. The wavelength of light that causes a structural change in the photoreactive structure is not particularly limited, but is preferably 150 to 800 nm, more preferably 200 to 400 nm, and even more preferably 300 to 400 nm. Moreover, it is preferable that the light irradiation intensity | strength required for producing a structural change in a photoreactive structure is 0.05-20 J / cm < ² >.

The “first monomer” in the present invention is a molecule of a compound that forms a polymer by polymerizing with other molecules contained in the monomer composition, and has a photoreactive structure at a portion that forms a constituent unit of the polymer. And a part forming the structural unit of the polymer causes a chemical reaction by heating. Further, the “second monomer” in the present invention is a molecule of a compound that forms a polymer by polymerizing with other molecules contained in the monomer composition, and photoreacts with a portion that forms a constituent unit of the polymer. The part which comprises a structural structure and forms the structural unit of the polymer does not cause a chemical reaction by heating.
Here, in the first monomer and the second monomer, the “part forming the polymer structural unit” refers to a polymerizable group (polymerization of other molecules during polymerization) in the molecules constituting the monomer. It means an atomic group excluding a terminal group that reacts with a functional group to form a bond, in other words, a portion that remains after polymerization and constitutes a structural unit of the polymer. In the following description, the “part forming the structural unit of the polymer” may be referred to as the “structural unit forming part”.
In the present invention, among monomers containing a photoreactive structure in the structural unit forming part, when a film made of a polymer of the monomer is allowed to stand at 200 ° C. for 10 minutes, the photoreactive structure has a thickness of 200 nm to 900 nm. The monomer whose transmittance at the maximum absorption wavelength in the range of 20% or more changes from the transmittance before standing at least 20% corresponds to the monomer in which the structural unit forming part undergoes a chemical reaction by heating, that is, the “first monomer” A monomer that does not show a change in transmittance due to heating is a “second monomer”.
In the first monomer, the chemical reaction caused by heating is not particularly limited, but is preferably a reaction that converts a photoreactive group having a photoreactive structure into a structure having no photoreactivity, Particularly preferred is a cyclization reaction with another group of the monomer molecule. Thereby, the linearity of a polymer becomes high and the liquid crystal aligning film with higher orientation can be obtained.

The “polymer component” in the present invention is composed of a polymer obtained by polymerizing a monomer composition containing at least a first monomer and a second monomer, or a derivative thereof, and usually contains a plurality of polymer molecules or a plurality of polymers. It is an assembly of derivative molecules. The “polymer” constituting the polymer component includes the first monomer and the second monomer in the monomer composition as a raw material, so that the structural unit derived from the first monomer and the second monomer Includes derived structural units. However, a part of the polymer constituting the polymer component may include only one of the structural unit derived from the first monomer and the structural unit derived from the second monomer. In the following description, among the structural units constituting the polymer, the structural unit derived from the first monomer is referred to as “first structural unit”, and the structural unit derived from the second monomer is referred to as “second structural unit”. It is called “unit”.
The “derivative” of a polymer in the present invention means one obtained by replacing a part of a polymer obtained by polymerizing a monomer composition with another atom or atomic group. The derivative is preferably a derivative in which a part other than the first structural unit and the second structural unit of the polymer is replaced with another atom or atomic group.
In a polymer obtained by polymerizing a monomer composition or a derivative thereof, the structural unit derived from the first monomer (first structural unit) was included in the structural unit forming part of the first monomer “photoreactivity. The structural unit that includes a “structure” and causes a chemical reaction upon heating, and the structural unit derived from the second monomer (second structural unit) was included in the structural unit forming part of the second monomer. It is a structural unit that includes a “photoreactive structure” and does not cause a chemical reaction upon heating. That is, the “polymer component” contained in the liquid crystal aligning agent of the present invention includes a photoreactive structure, a first structural unit that undergoes a chemical reaction by heating, a photoreactive structure, and by heating. It can also be said that it is a polymer aggregate containing a polymer containing a second structural unit that does not cause a chemical reaction or a derivative thereof.

  The liquid crystal aligning agent (liquid crystal aligning agent) for photo-alignment of this invention is used for formation of a liquid crystal aligning film. In order to form a liquid crystal alignment film with the liquid crystal aligning agent of the present invention, for example, a liquid crystal aligning agent is applied to a substrate to form a film, and then irradiated with polarized light for photo alignment. As a result, the photoreactive structure of the first structural unit and the second structural unit is selected in the polymer main chain (the main chain of the polymer constituting the polymer component or its derivative) that is substantially parallel to the polarization direction. In particular, a photochemical reaction is caused to change the structure, and a component in a specific direction in the polymer main chain (a component in a specific direction as a result of the change in the structure) becomes dominant. That is, the polymer main chain constituting the film is oriented in a specific direction and anisotropy is imparted. Thereafter, the photo-aligned film is heated and baked to form a solid liquid crystal alignment film. During this baking, in the present invention, the first structural unit of the polymer or derivative thereof undergoes a chemical reaction, the photoreactive group disappears, and the number of photoreactive groups decreases in the entire film. , No photoreactive group is present. Therefore, the formed liquid crystal alignment film hardly generates radicals even when exposed to strong light, and exhibits high stability to light. At this time, since the second structural unit retains the structure immediately after the photo-alignment treatment without causing a chemical reaction, the structure effectively contributes to the anisotropy of the polymer main chain. As a result, the formed liquid crystal alignment film exhibits good liquid crystal alignment in addition to high stability to light. Therefore, in a liquid crystal display element in which a liquid crystal alignment film is formed with this liquid crystal aligning agent, a high voltage holding ratio is maintained even when exposed to light from a backlight for a long time, and the contrast is high and a clear light / dark display is achieved. It can be carried out.

  Below, the polymer component which the liquid crystal aligning agent of this invention contains, the monomer composition used as the raw material of the polymer component, the polymer which superposes | polymerizes the monomer composition, or its derivative (s) is explained in full detail.

<Polymer component>
The liquid crystal aligning agent of this invention contains the polymer component which has a structural unit containing a photoreactive structure. When the polymer component is subjected to a photo-alignment treatment on the film of the liquid crystal aligning agent, the polymer main chain is oriented in a specific direction and exhibits anisotropy. In the following description, “a polymer component having a structural unit including a photoreactive structure” may be referred to as a “photoreactive polymer component”.
The photoreactive polymer component is composed of a polymer obtained by polymerizing a monomer composition containing at least a first monomer and a second monomer or a derivative thereof, and the constituent unit including the photoreactive structure is a monomer composition. Derived from the first monomer and the second monomer.
The liquid crystal aligning agent may contain one type of polymer component obtained from a single monomer composition, or may contain two or more types of polymer components having different monomer composition compositions. . Moreover, the liquid crystal aligning agent may contain both the polymer component which consists of a polymer which polymerizes a monomer composition, and the polymer component which consists of the derivative of the polymer.
Hereinafter, the monomer composition used as a raw material for the polymer component will be described.

<Monomer composition>
The monomer composition used in the present invention is a composition containing at least a first monomer and a second monomer, and may be composed of only the first monomer and the second monomer, or other monomers may be used. May be included.

[First monomer]
The first monomer is a compound that includes a photoreactive structure in a portion that forms a structural unit of the polymer (structural unit forming portion), and a portion that forms the structural unit of the polymer causes a chemical reaction by heating. is there. In the present invention, the constituent unit forming part of the first monomer is introduced into the polymer to form a first constituent unit containing a photoreactive structure and causing a chemical reaction by heating. The first monomer contained in the monomer composition may be only one type or two or more types.
In the following description, “monomer having a photoreactive structure in a constituent unit forming part” is sometimes expressed as “photoreactive”. For example, “a monomer having a photoreactive structure in a constituent unit forming part” Is sometimes referred to as “photoreactive monomer”. In addition, the property that the structural unit forming part causes a chemical reaction by heating may be referred to as “thermal reactivity”.
The constituent unit forming part of the first monomer may consist only of a photoreactive structure or may contain other structures. The number of photoreactive structures included in the structural unit forming part may be one or two or more. When the structural unit forming part includes two or more photoreactive structures, these photoreactive structures may be the same as or different from each other.

The structural unit forming part of the first monomer preferably has a photoreactive structure including at least one of the structure represented by the following formula (a-1) and the structure represented by the following formula (a-2). . Thereby, a polymer containing at least one of the structure represented by the formula (a-1) and the structure represented by the formula (a-2) as a constituent unit is obtained as a polymer obtained by polymerizing the monomer composition. be able to. In a liquid crystal aligning agent containing such a polymer or a derivative thereof as a polymer component, when the coating film of the liquid crystal aligning agent is heated, the substituent of the benzene ring and the photoreactive group in each formula undergo a cyclization reaction and light. The reactive group disappears and the number of photoreactive groups in the entire film is reduced or the photoreactive group is not present. As a result, a liquid crystal alignment film stable to light can be formed.
Here, the structural unit forming part may include only the structure represented by the formula (a-1) or may include only the structure represented by the formula (a-2). Both the structure represented by 1) and the structure represented by formula (a-2) may be included. In addition, the number of structures represented by the formula (a-1) and the number of structures represented by the formula (a-2) included in the structural unit forming part may be two or more even if each is one. There may be. When the structural unit forming part includes two or more structures represented by the formula (a-1), these structures may be the same or different from each other, and the structural unit forming part may be represented by the formula (a- When two or more structures represented by 2) are included, these structures may be the same as or different from each other.

In formula (a-1), R ^a represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted arylcarbonyl group. In formula (a-2), R ^b and R ^c are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted group Alternatively, it represents an unsubstituted arylcarbonyl group. R ^b and R ^c may be the same or different from each other. In the formula (a-1) and the formula (a-2), * is a bonding position with a photoreactive group. * May be directly bonded to the photoreactive group, or may be linked to the photoreactive group through a divalent group.

In formula (a-1), the alkyl group in R ^a may be linear, branched or cyclic. The carbon number of the alkyl group is preferably 1 to 10, more preferably 1 to 6, further preferably 1 to 4, and still more preferably 1 to 3. Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1 Examples include -methylbutyl group, 1-ethylpropyl group, hexyl group, isohexyl group, 1-methylpentyl group, 1-ethylbutyl group and the like.
The alkanoyl group in R ^a may be linear, branched or cyclic. The carbon number of the alkanoyl group is preferably 1 to 10, more preferably 1 to 6, still more preferably 1 to 2, and even more preferably 1. Specific examples of the alkanoyl group include methanoyl group, ethanoyl group, propanoyl group, isopropanoyl group, butanoyl group, isobutanoyl group, sec-butanoyl group, tert-butanoyl group, pentanoyl group, isopentanoyl group, neopentanoyl group, Examples thereof include a tert-pentanoyl group, 1-methylbutanoyl group, 1-ethylpropanoyl group, hexanoyl group, isohexanoyl group, 1-methylpentanoyl group, 1-ethylbutanoyl group and the like.

The alkoxycarbonyl group in R ^a may be linear, branched or cyclic. The carbon number of the alkoxycarbonyl group is preferably 1 to 10, more preferably 1 to 6, still more preferably 1 to 3, and even more preferably 2. Specific examples of the alkoxycarbonyl group include a methyloxycarbonyl group, an ethyloxycarbonyl group, a propyloxycarbonyl group, an isopropyloxycarbonyl group, a butyloxycarbonyl group, an isobutyloxycarbonyl group, a sec-butyloxycarbonyl group, and a tert-butyloxycarbonyl group. Group, pentyloxycarbonyl group, isopentyloxycarbonyl group, neopentyloxycarbonyl group, tert-pentyloxycarbonyl group, 1-methylbutyloxycarbonyl group, 1-ethylpropyloxycarbonyl group, hexyloxycarbonyl group, isohexyloxy Examples include carbonyl group, 1-methylpentyloxycarbonyl group, 1-ethylbutyloxycarbonyl group and the like.
The aryl group of the arylcarbonyl group in R ^a may be a single ring or a condensed ring. The aryl group preferably has 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, and still more preferably 6 to 10 carbon atoms. Specific examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. Specific examples of the arylcarbonyl group include a phenylcarbonyl group and a 1-naphthylcarbonyl group.
The alkyl group, alkanoyl group, alkoxycarbonyl group, and arylcarbonyl group in R ^a may each be substituted with a substituent. Examples of the substituent include a hydroxyl group, an amino group, and a halogeno group.
Of these, ^Ra is preferably ^a methyl group, an ethyl group, a propyl group, a hydrogen atom, a methanoyl group, or a phenyl group from the viewpoint that the performance of the finally produced liquid crystal alignment film can be improved.

In the formula (a-2), the description, preferred range and specific examples of the alkyl group, alkanoyl group, alkoxycarbonyl group, arylcarbonyl group and substituents that can be substituted on these groups in R ^b and R ^c are as described above. For the alkyl group, alkanoyl group, alkoxycarbonyl group, arylcarbonyl group and the substituents that can be substituted on these groups in R ^a of formula (a-1), reference can be made to preferred explanations and specific examples.

In formula (a-1) and formula (a-2), the photoreactive group bonded to * is not particularly limited, but an azo group, 1,2-ethenediyl group, 1,2-ethynediyl group, imino group, A carbonyl group, an oxycarbonyl group, etc. can be mentioned.
The hydrogen atom of each benzene ring in formula (a-1) and formula (a-2) may be substituted with a substituent. For the preferred range and specific examples of the substituent, in the following formula (1), the preferred range and specific examples of the substituent that can be substituted on the benzene ring can be referred to.

  The photoreactive structure having at least one of the structure represented by the formula (a-1) and the structure represented by the formula (a-2) preferably constitutes an azobenzene structure. It is more preferable that the structure is represented. When the structure represented by the following formula (1) is irradiated with ultraviolet rays, trans-cis isomerization of the azo group occurs and the direction of the polymer main chain changes. Thereby, a liquid crystal alignment film in which the polymer main chain is aligned in a specific direction is obtained.

In Formula (1), R ¹ and R ² each independently represent a hydrogen atom, a group represented by Formula (1-1) or Formula (1-2), and at least one of R ¹ and R ² Is a group represented by formula (1-1) or formula (1-2). Among R ¹ and R ^2, the group represented by formula (1-1) or formula (1-2) may be either ^one or both of R ¹ and R ^2. . When both R ¹ and R ² are groups represented by formula (1-1) or formula (1-2), these groups may be the same or different from each other.
* Represents a bonding position to the structure on both sides of the structure represented by the formula (1), and one of the positions that can be substituted with a hydrogen atom in one benzene ring, or the hydrogen atom in the other benzene ring One of the replaceable positions.

In Formula (1-1), R ⁴ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group. Represent. In formula (a-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted group Alternatively, it represents an unsubstituted arylcarbonyl group. R ⁴ and R ⁵ may be the same or different from each other. In Formula (1-1) and Formula (1-2), * represents the bonding position to each benzene ring in Formula (1). For the explanation and preferred ranges and specific examples of the alkyl group, alkanoyl group, alkoxycarbonyl group, arylcarbonyl group and substituents that can be substituted on these groups in R ⁴ and R ^5, R in the above formula (a-1) ^For the alkyl group, alkanoyl group, alkoxycarbonyl group, arylcarbonyl group and the substituents that can be substituted on these groups in a, the preferred ranges and specific examples can be referred to.

  The hydrogen atom of the benzene ring in formula (1) may be substituted with a substituent. Preferable examples of the substituent include an alkyl group, an alkoxy group, a halogenated alkyl group, a halogeno group, and a carboxyalkyl group. The alkyl group may be linear, branched or cyclic. The carbon number of the alkyl group is preferably 1 to 4, more preferably 1 to 2. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. The preferable carbon number of the alkoxy group is 1 to 4, more preferably 1 to 2. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group. A trifluoromethyl group etc. can be illustrated as a specific example of a halogenated alkyl group. Specific examples of the halogeno group include a fluoro group, a chloro group, a bromo group, and an iodo group. Specific examples of the carboxyalkyl group include a carboxymethyl group and a carboxyethyl group.

  Examples of the photoreactive structure to be introduced into the constituent unit forming part of the first monomer include the above-mentioned azobenzene structure, photoisomerization structure such as stilbene structure and acylhydrazone structure, and photofries rearrangement structure such as phenylester structure. It is done. The photoreactive structure included in the constituent unit forming part of the first monomer is preferably a photoisomerization structure such as an azobenzene structure, a stilbene structure, or an acylhydrazone structure, and an azobenzene structure is particularly preferable.

(Chemical reaction by heating structural units with photoreactive structure)
The constituent unit forming part of the first monomer used in the present invention has a photoreactive structure and causes a chemical reaction by heating. As a result, in the polymer or derivative thereof in which the structural unit forming portion is introduced as the first structural unit, anisotropy is imparted by a photo-alignment method (the light-reactive structure undergoes a structural change by light irradiation). Then, the photoreactive structure can be converted into a light-stable structure by heating.
As an example of a structure having a photoreactive structure and causing a chemical reaction upon heating, a structure in which a substituent is introduced at a specific position of an azobenzene structure, an acyl hydrazone structure, or a phenyl ester structure will be described. The mechanism by which the photoreactive group disappears due to the reaction will be described. The structure represented by the following formula (A-1) is included in the structure represented by the formula (1), and is more preferable as a photoreactive structure to be introduced into the first monomer. Moreover, the structure represented by the following formula (B-1), (C-1) or (D-1) can also be preferably used as the photoreactive structure to be introduced into the first monomer.

(A) Cyclization reaction of azobenzene structure: 5-membered ring formation An azobenzene structure having a substituent R ^1A in the ortho position relative to the azo group of one benzene ring, that is, an azobenzene structure represented by the following formula (A-1) In the first structural unit, the azo group reacts with the substituent R ^{1A of the} benzene ring to form an indazole ring by heating, as shown in the following reaction formula, and the azo group disappears. For details of this reaction, New J. chem., 1999, 23, 1223-1230 can be referred to.

In Formula (A-1), R ^1A represents a group represented by Formula (A-1-1) or Formula (A-1-2). In formula (A-1-1) and formula (A-1-2), R ^4A and R ^5A are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, A substituted or unsubstituted alkoxycarbonyl group or a substituted or unsubstituted arylcarbonyl group is represented. For the explanation and preferred ranges of R ^4A and R ^5A , and specific examples thereof, the alkyl group, alkanoyl group, alkoxycarbonyl group, arylcarbonyl group and substitution which can be substituted on these groups in R ^a of the above formula (a-1) Reference can be made to the description of groups, preferred ranges and specific examples.

(B) Cyclization reaction of azobenzene structure: 6-membered ring formation An azobenzene structure having a substituent (—CH ₂ COOR ^1B ) at the ortho position relative to the azo group of one benzene ring, that is, represented by the following formula (B-1) In the first structural unit having an azobenzene structure, as shown in the following reaction formula, by heating, the azo group reacts with a substituent (—CH ₂ COOR ^1B ) of the benzene ring to form a cyclic structure. The group disappears.

In formula (B-1), R ^1B represents a hydrogen atom or a substituted or unsubstituted alkyl group. Descriptions and preferred ranges and specific examples of the alkyl group and the substituents that can be substituted on the alkyl group are as follows. Descriptions and preferred ranges and specific examples of the alkyl group and its substituents in R ^a of the above formula (a-1) You can refer to it.

(C) Cyclization reaction of acyl hydrazone structure: 5-membered ring formation An acyl hydrazone structure having a substituent R ^1C in the ortho position relative to the imino group in the benzene ring, that is, an acyl hydrazone structure represented by formula (C-1) In the first structural unit, the imino group (= NR) reacts with the substituent R ^{1C of the} benzene ring by heating to form a cyclic structure as shown in the following reaction formula, and the imino group disappears.

In Formula (C-1), R ^1C represents a group represented by Formula (C-1-1) or Formula (C-1-2). In formula (C-1), formula (C-1-1) and formula (C-1-2), R ^2C , R ^4C and R ^5C each independently represent a hydrogen atom, substituted or unsubstituted alkyl Represents a group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group. For the explanation and preferred ranges and specific examples of the alkyl group, alkanoyl group, alkoxycarbonyl group, arylcarbonyl group and substituents that can be substituted on these groups in R ^2C , R ^4C and R ^5C , the above formula (a-1 ) Of R ^a ), description and preferred ranges and specific examples of substituents that can be substituted on these groups can be referred to.

(D) Cyclization reaction after Fries rearrangement: 5-membered ring formation A phenyl ester structure having a substituent (—CH ₂ NHR ^1D ) at the ortho position relative to the ester bond site of the benzene ring, that is, represented by the following formula (D-1) As shown in the following reaction formula, after the Fries rearrangement, the carbonyl group reacts with a benzene ring substituent (—CH ₂ NHR ^1D ) to form a cyclic structure, and the carbonyl group disappears. To do.

In formula (D-1), R ^1D represents a substituted or unsubstituted alkyl group. Descriptions and preferred ranges and specific examples of the alkyl group and the substituents that can be substituted on the alkyl group are as follows. Descriptions and preferred ranges and specific examples of the alkyl group and its substituents in R ^a of the above formula (a-1) You can refer to it.

  Whether or not the first structural unit containing a photoreactive structure has caused a chemical reaction can be confirmed by an ultraviolet-visible absorption spectrum (transmittance), a nuclear magnetic resonance (NMR) spectrum, or an infrared spectroscopy (IR) spectrum. it can. For example, when the photoreactive structure constitutes an azobenzene structure, it is possible to confirm that the cyclization reaction has occurred by increasing the transmittance at 365 nm, which is the absorption wavelength of azobenzene. . Here, in the liquid crystal aligning agent using the 1st monomer which contains an azobenzene structure as a photoreactive structure, it is preferable that the transmittance | permeability of 365 nm rises 10% or more by the chemical reaction by heating. Specifically, when the film made of the liquid crystal aligning agent is heated and baked at 230 ° C. for 30 minutes, the transmittance of the film at 365 nm may increase by 10% or more from the transmittance at 365 nm of the film before heating and baking. preferable. In such a liquid crystal aligning agent, the photoreactivity of the azobenzene structure can be reliably reduced by performing a photo-alignment treatment on the film and then heating. Thereby, the liquid crystal aligning film which has high light stability and shows favorable liquid crystal aligning property can be formed.

(Example of first monomer compound)
A preferred example of the first monomer is a diamine represented by the formula (2).
The diamine represented by the formula (2) has an azobenzene structure common to the structure represented by the formula (1). Therefore, for example, using this diamine as the first monomer and using tetracarboxylic dianhydride or a derivative thereof as the second monomer or other monomer, a polymer obtained by polymerizing the monomer composition has the formula A polyamic acid, a polyamic acid ester, a polyamic acid-polyamide copolymer, or the like having the structure represented by (1) as a structural unit of the main chain can be obtained. Furthermore, derivatives such as polyimide, partial polyimide, polyamic acid ester and the like can be produced from this polyamic acid, and derivatives such as polyamideimide can be produced from the polyamic acid-polyamide copolymer. Thereby, the various derivatives which contain the structure represented by Formula (1) in the structural unit of a principal chain can be obtained. For a detailed description of the polymer or derivative obtained by polymerizing the monomer composition, refer to [Polymer obtained by polymerizing monomer composition or derivative thereof] and (Method for synthesizing polymer from monomer composition). Reference can be made to the description.

In Formula (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by Formula (1-1) or Formula (1-2), and at least one of R ¹ and R ² Is a group represented by formula (1-1) or formula (1-2). For a description of R ¹ and R ² in Formula (2) it may refer to the description of R ¹ and R ² in the formula (1).
R ⁶ and R ⁸ are each independently a linear alkylene group having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, —CON (CH ₃ ) — or a single bond is represented. In R ⁶ and R ⁸ , one of the straight chain alkylene groups —CH ₂ — or two not adjacent to each other may be replaced by —O—. R ⁶ and R ⁸ may be the same or different from each other. R ⁷ and R ⁹ each independently represents a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, a heterocyclic ring, or a single bond. R ⁷ and R ⁹ may be the same or different from each other.
The monocyclic hydrocarbon in R ⁷ and R ⁹ may be an alicyclic ring or an aromatic ring. The monocyclic hydrocarbon preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and still more preferably 6 to 8 carbon atoms. Specific examples of the monocyclic hydrocarbon include a benzene ring, a cyclohexane ring, and a cyclohexene ring.
The carbon number of the condensed polycyclic hydrocarbon in R ⁷ and R ⁹ is preferably 10 to 26, more preferably 10 to 18, and further preferably 10 to 14. Specific examples of the condensed polycyclic hydrocarbon include a naphthalene ring, an anthracene ring, and a phenanthrene ring.
The heterocyclic ring in R ⁷ and R ⁹ may be an alicyclic ring or an aromatic ring. It is preferable that carbon number of a heterocyclic ring is 1-26, It is more preferable that it is 3-14, It is further more preferable that it is 3-8. Examples of the hetero atom that the heterocyclic ring contains as a ring member include a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples of the heterocyclic ring include a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, an indole ring, and an oxazole ring.
In the formula (2), —R ⁶ —R ⁷ —NH ₂ is bonded to one benzene ring in the formula (2), and the bonding position thereof is any position that can be substituted with a hydrogen atom in the benzene ring. It is. —R ⁸ —R ⁹ —NH ₂ is bonded to the other benzene ring in the formula (2), and the bonding position thereof is one of the positions that can be substituted with a hydrogen atom in the benzene ring. The remaining substitutable positions of the benzene ring may be unsubstituted or substituted with a substituent. For the preferred range and specific examples of the substituent, in the above formula (1), the preferred range and specific examples of the substituent that can be substituted on the benzene ring can be referred to.

In Formula (1-1), R ⁴ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group. Represent. In formula (1-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted group Alternatively, it represents an unsubstituted arylcarbonyl group. In the formulas (1-1) and (1-2), * represents the bonding position to the benzene ring in the formula (2). Equation (1-1), R ^4, R ⁵ in (1-2), the description of the * formula in the formula (1) (1-1), R 4, R 5 in (1-2), * Reference can be made to the description.

The diamine represented by the formula (2) is a diamine represented by any one of the following formulas (3) to (6), from the viewpoint of ease of synthesis, availability of raw materials, and high liquid crystal orientation. It is preferable.

In the formula (3) ~ (6), R ⁴ and R ⁵ have the same meanings as R ⁴ and R ⁵ in formulas (1-1) and (1-2) of formula (2). R ⁴ and R ⁵ are preferably each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkanoyl group having 1 to 10 carbon atoms. R ⁴ each other formula (3), R ⁴ to each other, R ⁵ together and R ⁴ and R ⁵ of formula (5), R ⁴ and R ⁵ of formula (6) are each not being the same or different However, they are preferably the same.

Preferable specific examples of the diamine represented by any one of formulas (3) to (6) include formulas (3-1) to (3-9), formulas (4-1) to (4-9), formula ( Examples of the diamine represented by any one of (5-1), Formula (5-2), Formula (6-1), and Formula (6-2). Polymer components synthesized using these diamines as the first monomer tend to exhibit high liquid crystal alignment. In the formulas, Me represents respectively a methyl group, Et represents an ethyl group, Pr is propyl, ⁱ Pr is an isopropyl group, Bu a butyl group, ^t Bu is a t- butyl group.

(Synthesis of diamine)
The diamine represented by any of the above formulas (3) to (6) can be synthesized as follows.
In order to synthesize the diamine represented by formula (3), commercially available 5-nitroanthranilic acid is reduced to obtain 2-amino-5-nitrophenylmethanol, and then the aromatic amine is oxidized in the benzene ring. An azobenzene having a hydroxymethyl group at the ortho position of the azo group and a nitro group at the para position is obtained. Subsequently, the hydroxyl group is changed to trifluoromethanesulfonic acid ester and converted to an alkoxy group by nucleophilic substitution reaction. Finally, the target diamine is obtained by reducing the nitro group.

  In order to synthesize the diamine represented by the formula (4), 1-alkoxymethyl-3-nitrobenzene is obtained from commercially available 1-bromomethyl-3-nitrobenzene by nucleophilic substitution reaction, and then the nitro group is reduced to produce 3- Alkoxymethylaniline is obtained. Subsequently, azobenzene is synthesized by diazo coupling with 4-nitroaniline, and the target diamine is obtained by reducing the nitro group.

  In order to synthesize the diamine represented by the formula (5), a commercially available 5-nitroanthranilic acid is reduced to give 2-amino-5-nitrophenylmethanol, and then the aromatic amine is oxidized in the benzene ring. An azobenzene having a hydroxymethyl group at the ortho position of the azo group and a nitro group at the para position is obtained. Subsequently, the hydroxyl group is changed to trifluoromethanesulfonic acid ester, and the N, N'-dialkylamino group is obtained by nucleophilic substitution reaction. Finally, the target diamine is obtained by reducing the nitro group.

  In order to synthesize the diamine represented by formula (6), N, N′-dialkyl-1- (3-nitrophenyl) methanamine was obtained from commercially available 1-bromomethyl-3-nitrobenzene by nucleophilic substitution reaction, Reduction of the nitro group gives dialkylaminomethyl-3-nitrobenzene. Subsequently, azobenzene is synthesized by diazo coupling with 4-nitroaniline, and the target diamine is obtained by reducing the nitro group.

  These diamines can also be used after being purified by recrystallization or column chromatography.

  In order to provide a liquid crystal aligning agent that can be a liquid crystal alignment film having higher liquid crystal alignment properties, among these compounds, the formula (4-1), formula (4-2), formula (4-3), formula ( It is preferable to use at least one diamine represented by any one of 4-4), formula (4-5) and formula (6-1) as the first monomer.

[Second monomer]
The second monomer includes a photoreactive structure in a part (structural unit forming part) that forms a constituent unit of the polymer, and the part that forms the constituent unit of the polymer does not cause a chemical reaction by heating. It is. In the present invention, the constituent unit forming part of the second monomer is introduced into the polymer to form a second constituent unit that includes a photoreactive structure and does not cause a chemical reaction by heating. The liquid crystal aligning agent contains such a polymer having the second structural unit as a polymer component, so that when the film is subjected to photo-alignment treatment and then heated and fired, the second structural unit is subjected to photo-alignment treatment. The alignment state immediately after is maintained and contributes effectively to the anisotropy of the polymer main chain. Therefore, the obtained liquid crystal alignment film exhibits excellent liquid crystal alignment. Here, the second monomer contained in the monomer composition may be one type or two or more types.
The constituent unit forming part of the second monomer may consist of only a photoreactive structure or may contain other structures. The number of photoreactive structures included in the structural unit forming part may be one or two or more. When the structural unit forming part includes two or more photoreactive structures, these photoreactive structures may be the same as or different from each other.
The photoreactive structure introduced into the constituent unit forming part of the second monomer is preferably a photoisomerization structure or a photodimerization structure, and more preferably a photoisomerization structure. Examples of the photoisomerization structure include an azobenzene structure, a stilbene structure, and an acyl hydrazone structure. Examples of the photodimerization structure include a coumarin structure, a cinnamate structure, a chalcone structure, and a tolan structure.

(Example of second monomer compound)
As the second monomer, the following formula (II-1), formula (II-2), formula (III-1), formula (III-2), formula (IV-1), formula (IV-2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula A compound represented by any one of (VIII-1) and formula (VIII-2) can be used.

In the above formulas, a group whose bonding position is not fixed to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary. In the formula (IV-3), r is an integer of 1 to 10. In formula (V-2), R ⁶ independently represents —CH ₃ , —OCH ₃ , —CF ₃ , or —COOCH ₃ , and a is independently an integer of 0 to 2. In formula (V-3), ring A and ring B each independently represent at least one selected from monocyclic hydrocarbons, condensed polycyclic hydrocarbons and heterocyclic rings. R ¹¹ represents a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, or —CON (CH ₃ ) —, R ¹² represents a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, or —CON (CH ₃ ) —, In R ¹¹ and R ¹² , one or two of —CH ₂ — of the linear alkylene may be substituted with —O—, and R ^{7 to} R ¹⁰ are each independently —F, —CH _3. , —OCH ₃ , —CF ₃ , or —OH, and b to e are each independently an integer of 0 to 4. In the formula (VII-1), R ⁴ and R ⁶ are each independently a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ). CO—, —CON (CH ₃ ) —, or a single bond, and in R ⁴ and R ⁶ , one or non-adjacent two of the linear alkylene —CH ₂ — may be replaced by —O—. , R ⁵ and R ⁷ independently represent a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, a heterocyclic ring, or a single bond.

The monocyclic hydrocarbon in ring A and ring B of formula (V-3) and R ⁵ and R ⁷ in formula (VII-1) may be an alicyclic ring or an aromatic ring. The monocyclic hydrocarbon preferably has 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms, and still more preferably 6 to 8 carbon atoms. Specific examples of the monocyclic hydrocarbon include a benzene ring, a cyclohexane ring, and a cyclohexene ring.
The condensed polycyclic hydrocarbon in ring A and ring B in formula (V-3) and R ⁵ and R ⁷ in formula (VII-1) preferably has 10 to 26 carbon atoms, It is more preferable that it is 10-14. Specific examples of the condensed polycyclic hydrocarbon include a naphthalene ring, an anthracene ring, and a phenanthrene ring.
The heterocyclic ring in ring A and ring B of formula (V-3) and R ⁵ and R ⁷ in formula (VII-1) may be an alicyclic ring or an aromatic ring. It is preferable that carbon number of a heterocyclic ring is 1-26, It is more preferable that it is 3-14, It is further more preferable that it is 3-8. Examples of the hetero atom that the heterocyclic ring contains as a ring member include a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples of the heterocyclic ring include a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, an indole ring, and an oxazole ring.

The diamine represented by the formula (2) is used as the first monomer, and the formula (II-1), the formula (III-1), the formula (IV-1), and the formula (IV-3) are used as the second monomer. As a polymer obtained by polymerizing a monomer composition by using a compound (tetracarboxylic dianhydride) represented by any one of formulas (V-1) and (VI-1), 1) as well as the formula (II-1), formula (III-1), formula (IV-1), formula (IV-3), formula (V-1), or formula (VI- The structure of the part except -CO-O-CO- in 1) and a polyamic acid having a carbonyl group and a carboxyl group converted from -CO-O-CO- in the main chain constituent unit can be obtained. The diamine represented by the formula (2) is used as the first monomer, and the formula (II-2), the formula (III-2), the formula (IV-2), and the formula (V-2) are used as the second monomer. A compound (diamine) represented by any one of formula (V-3), formula (VI-2), formula (VII-1), formula (VIII-1) and formula (VIII-2) For example, a polymer obtained by polymerizing a monomer composition by using tetracarboxylic dianhydride or a derivative thereof as another monomer, and a structure represented by the formula (II-2) ), Formula (III-2), formula (IV-2), formula (V-2), formula (V-3), formula (VI-2), formula (VII-1), formula (VIII-1) Or the structure of the portion excluding —NH ₂ in formula (VIII-2), and —N converted from —NH ₂ A polyamic acid, a polyamic acid ester, a polyamic acid-polyamide copolymer, and the like having H- as a constituent unit of the main chain can be obtained. Furthermore, derivatives such as polyimide, partial polyimide, and polyamic acid ester can be generated from polyamic acid, and derivatives such as polyamideimide can be generated from polyamic acid-polyamide copolymer. Thereby, the structure represented by Formula (1), Formula (II-1), Formula (II-2), Formula (III-1), Formula (III-2), Formula (IV-1), Formula (IV-2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula Various derivatives having the structure of the portion excluding —CO—O—CO— and —NH ₂ in (VII-1), formula (VIII-1), or formula (VIII-2) as the structural unit of the main chain are obtained. be able to.
For a detailed description of the polymer or derivative obtained by polymerizing the monomer composition, refer to [Polymer obtained by polymerizing monomer composition or derivative thereof] and (Method for synthesizing polymer from monomer composition). Reference can be made to the description.

  As the second monomer, among the above, the formula (II-1), the formula (II-2), the formula (III-1), the formula (III-2), the formula (IV-1), the formula (IV- 2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1) ) Is preferred. In addition, the compounds represented by the above formula (V-1), formula (V-2), formula (VI-1), formula (VI-2) and formula (VII-1) are from the point of photosensitivity. More preferred. In formula (V-2) and formula (VI-2), a compound in which the bonding positions of the two amino groups are both in the para position is particularly preferable. Furthermore, in Formula (V-2), the compound of a = 0 can be used more suitably from the point of the orientation.

  As more preferred specific examples of the second monomer, the following formula (V-2-1), formula (V-3-2), formula (VI-2-1), formula (VII-1-1) and formula ( And VII-1-2).

[Amount of the first monomer and the second monomer in the monomer composition]
The blending amount of the second monomer in the monomer composition is preferably 15 to 85 mol%, more preferably 15 to 40 mol%, based on the total number of moles of the first monomer and the second monomer. Preferably, it is 20-30 mol%, and it is further more preferable.
The blending amount of the first monomer in the monomer composition is preferably 5 to 45 mol%, more preferably 25 to 45 mol%, based on the total number of moles of all monomer components constituting the monomer composition. Preferably, it is 25-40 mol%, and it is further more preferable.
The blending amount of the second monomer in the monomer composition is preferably 5 to 40 mol%, more preferably 10 to 30 mol%, based on the total number of moles of all monomer components constituting the monomer composition. Preferably, it is 10-25 mol%, and it is still more preferable.
When the polymer obtained from the monomer composition is a polyamic acid or a derivative thereof and the first monomer is a diamine, the amount of the diamine in the monomer composition is based on the total amount of diamine contained in the monomer composition. 15-80 mol% is preferable and 50-80 mol% is more preferable.
When the polymer obtained from the monomer composition is a polyamic acid or a derivative thereof and the second monomer is a diamine, the amount of the diamine in the monomer composition is based on the total amount of diamine contained in the monomer composition. 15-80 mol% is preferable and 20-50 mol% is more preferable.

[Other monomers]
The monomer composition may contain a monomer that does not contain a photoreactive structure in a monomer other than the first monomer and the second monomer, that is, a part that forms a structural unit (structural unit forming part).
In the following description, the fact that a monomer “does not contain a photoreactive structure in the structural unit forming part” is sometimes expressed as “non-photoreactive”. For example, “a photoreactive structure is formed in the structural unit forming part. “Monomer not contained” is sometimes referred to as “non-photoreactive monomer”.
For example, the diamine represented by the formula (2) is used as the first monomer, and the formula (II-1), the formula (II-2), the formula (III-1), and the formula (III-2) are used as the second monomer. ), Formula (IV-1), formula (IV-2), formula (IV-3), formula (V-1), formula (V-2), formula (V-3), formula (VI-1) , Formula (VI-2), Formula (VII-1), Formula (VIII-1), and Formula (VIII-2), in particular, Formula (II-2), Formula (III- 2), Formula (IV-2), Formula (V-2), Formula (V-3), Formula (VI-2), Formula (VII-1), Formula (VIII-1), and Formula (VIII-) 2) When using the compound (diamine) represented by any of the above, by using a non-photoreactive tetracarboxylic dianhydride as another monomer, the monomer A polyamic acid can be obtained as a polymer obtained by polymerizing the composition, and a monomer composition can be polymerized by using a non-photoreactive tetracarboxylic dianhydride derivative as another monomer. As a polymer, a polyamic acid derivative such as a polyamic acid ester or a polyamic acid-polyamide copolymer can be obtained. For a detailed description of the polymer or derivative obtained by polymerizing the monomer composition, refer to [Polymer obtained by polymerizing monomer composition or derivative thereof] and (Method for synthesizing polymer from monomer composition). Reference can be made to the description.

(Non-photoreactive tetracarboxylic dianhydride)
The tetracarboxylic dianhydride as the non-photoreactive monomer can be selected without limitation from known tetracarboxylic dianhydrides. Such tetracarboxylic dianhydrides include aromatic systems (including heteroaromatic ring systems) in which dicarboxylic acid anhydrides are directly bonded to aromatic rings, and aliphatic groups in which dicarboxylic acid anhydrides are not directly bonded to aromatic rings. It may belong to any group of systems (including heterocyclic ring systems).

  Suitable examples of such tetracarboxylic dianhydrides include those represented by the following formulas (AN-I) to (AN-V) from the viewpoint of easy availability of raw materials, ease of polymer production, and electrical characteristics of the film. The tetracarboxylic dianhydride represented by either is mentioned.

Formula (AN-I), in formula (AN-IV) and formula (AN-V), X are each independently a single bond or -CH ₂ - represents a. In the formula (AN-II), G represents a single bond, an alkylene group having 1 to 20 carbon atoms, —CO—, —O—, —S—, —SO ₂ —, —C (CH ₃ ) ₂ —, —C. (CF ₃ ) ₂ — or a divalent group represented by the following formula (G13-1) is represented, and —CH ₂ — may be replaced by —O—, —CO—, or —NH—.

In formula (G13-1), G ^13a and G ^13b each independently represent a single bond or a divalent group selected from —O—, —CONH—, or —NHCO—. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.
In the formulas (AN-II) to (AN-IV), Y independently represents one selected from the following trivalent group. Each bond of the trivalent group is connected to either a carbon atom constituting the carbonyl group in each formula or a position replaceable with a hydrogen atom of ring A ¹⁰ . At least one hydrogen atom of the trivalent group may be substituted with a methyl group, an ethyl group, or a phenyl group.

In the formulas (AN-III) to (AN-V), the ring A ¹⁰ is independently a cyclic group obtained by removing hydrogen atoms from monocyclic hydrocarbons having 3 to 10 carbon atoms by the number of bonds, or 6 carbon atoms. The cyclic group which remove | excluded the hydrogen atom by the number of the bonds from -30 condensed polycyclic hydrocarbon is represented. At least one hydrogen atom in each cyclic group may be substituted with a methyl group, an ethyl group, or a phenyl group. In addition, the bond on each ring may be linked to any carbon constituting the ring, and the two bonds may be bonded to the same carbon atom.

  Furthermore, what is represented by either of the following formula | equation (AN-1)-a formula (AN-16-15) is mentioned as tetracarboxylic dianhydride.

Tetracarboxylic dianhydride represented by the formula (AN-1):

In the formula (AN-1), G ¹¹ represents a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group, or a 1,4-cyclohexylene group. X ¹¹ independently represents a single bond or —CH ₂ —. G ¹² independently represents any of the following trivalent groups.

When G ¹² is> CH—, the hydrogen atom of> CH— may be substituted with a methyl group. When G ¹² is> N—, G ¹¹ is not a single bond and —CH ₂ —, and X ¹¹ is not a single bond. R ¹¹ represents a hydrogen atom or a methyl group.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-1) include compounds represented by the following formula.

  In formula (AN-1-2) and (AN-1-14), m is an integer of 1-12 each independently.

Tetracarboxylic dianhydride represented by the formula (AN-2):

In the formula (AN-2), R ⁶¹ independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-2) include compounds represented by the following formula.

Tetracarboxylic dianhydride represented by the formula (AN-3):

In the formula (AN-3), ring A ¹¹ represents a cyclohexane ring or a benzene ring.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-3) include compounds represented by the following formula.

Tetracarboxylic dianhydride represented by the formula (AN-4):

In the formula (AN-4), G ¹³ is a single bond, — (CH ₂ ) _m —, —O—, —S—, —C (CH ₃ ) ₂ —, —SO ₂ —, —CO—, —C. (CF ₃ ) ₂ — or a divalent group represented by the following formula (G13-1) is represented, and m is an integer of 1 to 12. Each ring A ¹¹ independently represents a cyclohexane ring or a benzene ring. G ¹³ may be bonded to any position that can be substituted with the hydrogen atom of ring A ¹¹ .

In Formula (G13-1), G ^13a and G ^13b each independently represent a divalent group represented by a single bond, —O—, —CONH—, or —NHCO—. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-4) include compounds represented by the following formula.

In formula (AN-4-17), m is an integer of 1-12.

Tetracarboxylic dianhydride represented by the formula (AN-5):
In the formula (AN-5), R ¹¹ independently represents a hydrogen atom or a methyl group. Of the two R ^{11 s} , R ¹¹ in the benzene ring is bonded to any substitutable position of the benzene ring.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-5) include compounds represented by the following formula.

Tetracarboxylic dianhydride represented by the formula (AN-6):

In the formula (AN-6), X ¹¹ independently represents a single bond or —CH ₂ —. X ¹² is _{-CH 2 -, - CH 2 CH} 2 - or represents a -CH = CH-. n is 1 or 2. When n is 2, two X ¹² may be the same or different.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-6) include compounds represented by the following formula.

Tetracarboxylic dianhydride represented by the formula (AN-7):

In the formula (AN-7), X ¹¹ represents a single bond or —CH ₂ —.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-7) include compounds represented by the following formula.

Tetracarboxylic dianhydride represented by the formula (AN-8):

In the formula (AN-8), X ¹¹ represents a single bond or —CH ₂ —. R ¹² represents a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. Ring A ¹² represents a cyclohexane ring or a cyclohexene ring.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-8) include compounds represented by the following formula.

Tetracarboxylic dianhydride represented by the formula (AN-9):

In the formula (AN-9), each r is independently 0 or 1.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-9) include compounds represented by the following formula.

Tetracarboxylic dianhydrides represented by formula (AN-10-1) and formula (AN-10-2):

Tetracarboxylic dianhydride represented by the formula (AN-11):

In the formula (AN-11), ring A ¹¹ independently represents a cyclohexane ring or a benzene ring.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-11) include compounds represented by the following formula.

Tetracarboxylic dianhydride represented by the formula (AN-12):

In the formula (AN-12), each ring A ¹¹ independently represents a cyclohexane ring or a benzene ring.
As an example of the tetracarboxylic dianhydride represented by a formula (AN-12), the compound represented by a following formula can be mentioned.

Tetracarboxylic dianhydride represented by the formula (AN-15):

In formula (AN-15), w is an integer of 1-10.
Examples of the tetracarboxylic dianhydride represented by the formula (AN-15) include compounds represented by the following formula.

Examples of tetracarboxylic dianhydrides other than the above include the following compounds.

  In the tetracarboxylic dianhydride, a suitable material for improving each characteristic of the liquid crystal alignment film described later will be described. When importance is attached to improving the orientation of the liquid crystal, compounds represented by the formula (AN-1), the formula (AN-3), and the formula (AN-4) are preferred, and the formula (AN-1- 2), compounds represented by formula (AN-1-13), formula (AN-3-2), formula (AN-4-17), and formula (AN-4-29) are more preferred, In AN-1-2), m = 4 or 8 is preferable, and in formula (AN-4-17), m = 4 or 8 is preferable, and m = 8 is more preferable.

  When importance is attached to improving the transmittance of the liquid crystal display element, the formula (AN-1-1), the formula (AN-1-2), the formula (AN-3-1), the formula (AN-4-) 17), Formula (AN-4-30), Formula (AN-5-1), Formula (AN-7-2), Formula (AN-10-1), Formula (AN-16-3), Formula ( AN-16-4) and a compound represented by the formula (AN-2-1) are preferable, and in the formula (AN-1-2), m = 4 or 8 is preferable, and the formula (AN-4- In 17), m = 4 or 8 is preferable, and m = 8 is more preferable.

  When importance is attached to improving the VHR of the liquid crystal display element, the formula (AN-1-1), the formula (AN-1-2), the formula (AN-3-1), and the formula (AN-4-17). ), Formula (AN-4-30), Formula (AN-7-2), Formula (AN-10-1), Formula (AN-16-3), Formula (AN-16-4), and Formula ( In the formula (AN-1-2), m = 4 or 8 is preferable, and in the formula (AN-4-17), m = 4 or 8 is preferable. Is preferable, and m = 8 is more preferable.

  Increasing the relaxation rate of the residual charge (residual DC) in the liquid crystal alignment film by reducing the volume resistance value of the liquid crystal alignment film is effective as one method for preventing burn-in. When emphasizing this purpose, the formula (AN-1-13), the formula (AN-3-2), the formula (AN-4-21), the formula (AN-4-29), and the formula (AN- The compound represented by 11-3) is preferred.

(Non-photoreactive diamine and non-photoreactive dihydrazide)
When the monomer composition is a composition for synthesizing a polyamic acid or a derivative thereof, for example, the diamine represented by the formula (2) is included as the first monomer, and the formula (II-1) is included as the second monomer. , Formula (II-2), Formula (III-1), Formula (III-2), Formula (IV-1), Formula (IV-2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula (VIII-1), and Formula (VIII-2) In the case where it contains a compound represented by any one and further contains a non-photoreactive tetracarboxylic dianhydride or a derivative thereof, if necessary, a monomer composition containing a non-photoreactive diamine or a non-photoreactive dihydrazide You may make it contain. Thereby, the structural unit derived from the non-photoreactive diamine and the structural unit derived from the non-photoreactive dihydrazide can be introduced into the polymer obtained from the monomer composition, and the characteristics of the obtained liquid crystal alignment film are controlled. can do.
The diamine and dihydrazide used as the non-photoreactive monomer can be selected without limitation from known diamines and dihydrazides.

Diamines can be divided into two types according to their structures. That is, when a skeleton connecting two amino groups is viewed as a main chain, a group branched from the main chain, that is, a diamine having a side chain group and a diamine having no side chain group. In the following description, a diamine having such a side chain group may be referred to as a side chain diamine. Such a diamine having no side chain group may be referred to as a non-side chain diamine. This side chain group is a group having an effect of increasing the pretilt angle.
By properly using the non-side chain diamine and the side chain diamine, it is possible to cope with the pretilt angle required for each.

  The side chain diamine is preferably used in combination so as not to impair the properties of the present invention. The side chain diamine and non-side chain diamine are preferably selected and used for the purpose of improving the vertical alignment, VHR, image sticking characteristics and alignment with respect to the liquid crystal.

Known diamines and dihydrazides are shown below.

In the above formula (DI-1), G ²⁰ represents —CH ₂ — or a group represented by the formula (DI-1-a). When G ²⁰ is —CH ₂ —, at least one of m —CH ₂ — may be replaced by —NH—, —O—, and at least one hydrogen atom of m —CH ₂ —. May be substituted with a hydroxyl group. m is an integer of 1-12. When m in DI-1 is 2 or more, the plurality of G ²⁰ may be the same as or different from each other. However, when G ²⁰ is a group represented by the formula (DI-1-a), m is 1.

  In formula (DI-1-a), v is each independently an integer of 1 to 6.

In Formula (DI-3), Formula (DI-6), and Formula (DI-7), G ²¹ is independently a single bond, —NH—, —NCH ₃ —, —O—, —S—, —S. _{-S -, - SO 2 -,} - CO -, - COO -, - CONCH 3 -, - CONH -, - C (CH 3) 2 -, - C (CF 3) 2 -, - (CH 2) m _{-, - O- (CH 2)} m -O -, - N (CH 3) - (CH 2) k -N (CH 3) -, - (O-C 2 H 4) m -O -, - O _{-CH 2 -C (CF 3) 2} -CH 2 -O -, - O-CO- (CH 2) m -CO-O -, - CO-O- (CH 2) m -O-CO -, - _{(CH 2) m -NH- (CH} 2) m -, - CO- (CH 2) k -NH- (CH 2) k -, - (NH- (CH 2) m) k -NH -, - CO _{-C 3 H 6 - (NH-} C 3 H 6) n -CO- or -S- (CH _{2), m} represents -S-, m is independently an integer of 1 to 12, k is an integer of 1 to 5, and n is 1 or 2. In formula (DI-4), s is an integer of 0-2 independently.

In the formula (DI-5), G ³³ represents a single bond, —NH—, —NCH ₃ —, —O—, —S—, —S—S—, —SO ₂ —, —CO—, —COO—, —CONCH ₃ —, —CONH—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, — (CH ₂ ) _m —, —O— (CH ₂ ) _m —O—, —N ( _{CH 3) - (CH 2)} k -N (CH 3) -, - (O-C 2 H 4) m -O -, - O-CH 2 -C (CF 3) 2 -CH 2 -O-, —O—CO— (CH ₂ ) _m —CO—O—, —CO—O— (CH ₂ ) _m —O—CO—, — (CH ₂ ) _m —NH— (CH ₂ ) _m —, —CO _{- (CH 2) k -NH- (} CH 2) k -, - (NH- (CH 2) m) k -NH -, - CO-C 3 H 6 - (NH-C 3 H 6) n -CO -, or _{-S- (CH 2) m -S -} , - N (Boc) - (CH 2) e -N ( oc) -, - NH- (CH 2) e -N (Boc) -, - N (Boc) - (CH 2) e -, - (CH 2) m -N (Boc) -CONH- (CH 2) _{m -, - (CH 2)} m -N (Boc) - (CH 2) m -, a group represented by the following formula (DI-5-a) or the following formula (DI-5-b), m Is independently an integer of 1 to 12, k is an integer of 1 to 5, e is an integer of 2 to 10, and n is 1 or 2. Boc is a t-butoxycarbonyl group.

In the formula (DI-6) and the formula (DI-7), G ²² is independently a single bond, —O—, —S—, —CO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) _2- or an alkylene group having 1 to 10 carbon atoms.

Formula (DI-2) at least one hydrogen atom of the cyclohexane ring and benzene ring in ~ (DI-7) is, -F, -Cl, alkylene group having 1 to 3 carbon atoms, -OCH _3, -OH, - CF ₃ , —CO ₂ H, —CONH ₂ , —NHC ₆ H ₅ , a phenyl group, or a benzyl group may be substituted, and in Formula (DI-4), at least one of a cyclohexane ring and a benzene ring One hydrogen atom may be substituted with one selected from the group of groups represented by any of the following formulas (DI-4-a) to (DI-4-i), and the formula (DI-5 ), When G ³³ is a single bond, at least one hydrogen atom of the cyclohexane ring and the benzene ring may be substituted with NHBoc or N (Boc) ₂ .

A group in which the bonding position is not fixed to the carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary. The bonding position of —NH ₂ to the cyclohexane ring or the benzene ring is an arbitrary position excluding the bonding position of G ²¹ , G ²² or G ³³ .

In the formula (DI-4-a) and the formula (DI-4-b), R ²⁰ independently represents a hydrogen atom or —CH ₃ . In formula (DI-4-f) and formula (DI-4-g), m is each independently an integer of 0 to 12, and Boc is a t-butoxycarbonyl group.

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

In the formula (DI-11), r is 0 or 1. In formulas (DI-8) to (DI-11), the bonding position of —NH ₂ bonded to the ring is an arbitrary position.

In the formula (DI-12), R ²¹ and R ²² each independently represent an alkyl group having 1 to 3 carbon atoms or a phenyl group, and G ²³ independently represents an alkylene group having 1 to 6 carbon atoms or a phenylene group. Or the phenylene group substituted by the alkyl group is represented, and w is an integer of 1-10.
In the formula (DI-13), R ²³ independently represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or —Cl, p is independently an integer of 0 to 3; q is an integer of 0-4.
In the formula (DI-14), ring B represents a monocyclic heterocyclic aromatic group, R ²⁴ represents a hydrogen atom, —F, —Cl, an alkyl group having 1 to 6 carbon atoms, an alkoxy group, an alkenyl group, Represents an alkynyl group, q is independently an integer of 0 to 4; When q is 2 or more, the plurality of R ²⁴ may be the same as or different from each other.
In the formula (DI-15), ring C represents a heterocyclic aromatic group or a heterocyclic aliphatic group.
In the formula (DI-16), G ²⁴ represents a single bond, an alkylene group having 2 to 6 carbon atoms or a 1,4-phenylene group, and r is 0 or 1. A group whose bond position is not fixed to the carbon atoms constituting the ring indicates that the bond position in the ring is arbitrary.
In Formula (DI-13) to Formula (DI-16), the bonding position of —NH ₂ bonded to the ring is an arbitrary position.
Specific examples of the following formulas (DI-1-1) to (DI-16-1) can be given as diamines having no side chain of the above formulas (DI-1) to (DI-16). .

Examples of the diamine represented by the formula (DI-1) are shown below.

  In Formula (DI-1-7) and Formula (DI-1-8), k is each independently an integer of 1 to 3. In formula (DI-1-9), v is an integer of 1-6 each independently.

Examples of diamines represented by formulas (DI-2) to (DI-3) are shown below.

Examples of the diamine represented by the formula (DI-4) are shown below.

In formulas (DI-4-20) and (DI-4-21), m is each independently an integer of 1 to 12.

Examples of the diamine represented by the formula (DI-5) are shown below.
In formula (DI-5-1), m is an integer of 1-12.

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

In the formula (DI-5-16), v is an integer of 1 to 6.

In the formula (DI-5-30), k is an integer of 1 to 5.

In formula (DI-5-35) to formula (DI-5-37) and formula (DI-5-39), m is each independently an integer of 1 to 12, and formula (DI-5-38) ) And formula (DI-5-39), k is each independently an integer of 1 to 5, and in formula (DI-5-40), n is an integer of 1 or 2.

In formula (DI-5-42) to formula (DI-5-44), e is each independently an integer of 2 to 10, and in formula (DI-5-45), R ⁴³ is a hydrogen atom, —NHBoc Or -N (Boc) ₂ . In Formula (DI-5-42) to Formula (DI-5-44), Boc is a t-butoxycarbonyl group.

Examples of the diamine represented by the formula (DI-6) are shown below.

Examples of the diamine represented by the formula (DI-7) are shown below.
In formula (DI-7-3) and formula (DI-7-4), m is each independently an integer of 1 to 12, and n is independently 1 or 2.

Examples of the diamine represented by the formula (DI-8) are shown below.

Examples of the diamine represented by the formula (DI-9) are shown below.

Examples of the diamine represented by the formula (DI-10) are shown below.

Examples of the diamine represented by the formula (DI-11) are shown below.

Examples of the diamine represented by the formula (DI-12) are shown below.

Examples of the diamine represented by the formula (DI-13) are shown below.

Examples of the diamine represented by the formula (DI-14) are shown below.

Examples of the diamine represented by the formula (DI-15) are shown below.

Examples of the diamine represented by the formula (DI-16) are shown below.

  Examples of the dihydrazide having no known side chain include compounds represented by any of the following formulas (DIH-1) to (DIH-3).

In the formula (DIH-1), G ²⁵ represents a single bond, an alkylene group having 1 to 20 carbon atoms, —CO—, —O—, —S—, —SO ₂ —, —C (CH ₃ ) ₂ —, or -C (CF _{3) 2} - represents a.
In formula (DIH-2), ring D represents a cyclohexane ring, a benzene ring or a naphthalene ring, and at least one hydrogen atom of this group may be substituted with a methyl group, an ethyl group or a phenyl group. In formula (DIH-3), each ring E independently represents a cyclohexane ring or a benzene ring, and at least one hydrogen atom of this group may be substituted with a methyl group, an ethyl group, or a phenyl group. A plurality of E may be the same as or different from each other. Y represents a single bond, alkylene having 1 to 20 carbon atoms, —CO—, —O—, —S—, —SO ₂ —, —C (CH ₃ ) ₂ —, or —C (CF ₃ ) ₂ —. . In Formula (DIH-2) and Formula (DIH-3), the bonding position of -CONHNH ₂ bonded to the ring is an arbitrary position.

Examples of the compound represented by any one of formulas (DIH-1) to (DIH-3) are shown below.
In formula (DIH-1-2), m is an integer of 1-12.

  The diamine and dihydrazide as described above have an effect of improving electrical characteristics such as reducing the ion density of the liquid crystal display element.

  A diamine suitable for the purpose of increasing the pretilt angle will be described. Examples of the diamine having a side chain group suitable for the purpose of increasing the pretilt angle include any of formulas (DI-31) to (DI-35) and formulas (DI-36-1) to (DI-36-8). And diamines represented by

In the formula (DI-31), G ²⁶ represents a single bond, —O—, —COO—, —OCO—, —CO—, —CONH—, —CH ₂ O—, —OCH ₂ —, —CF ₂ O—. , -OCF ₂ -, or - (CH _{2) ma} - represents, ma is an integer from 1 to 12. Preferred examples of G ²⁶ are a single bond, —O—, —COO—, —OCO—, —CH ₂ O—, and an alkylene group having 1 to 3 carbon atoms, and particularly preferred examples are a single bond, —O—, -COO -, - OCO -, - CH 2 O -, - CH 2 - and -CH ₂ CH ₂ -. R ²⁵ represents an alkyl group having 3 to 30 carbon atoms, a phenyl group, a group having a steroid skeleton, or a group represented by the following formula (DI-31-a). In this alkyl group, at least one hydrogen atom may be substituted with —F, and at least one —CH ₂ — may be substituted with —O—, —CH═CH— or —C≡C—. Good. The hydrogen atom of the phenyl group is substituted with —F, —CH ₃ , —OCH ₃ , —OCH ₂ F, —OCHF ₂ , —OCF 3, an alkyl group having 3 to 30 carbon atoms, or an alkoxy group having 3 to 30 carbon atoms. May be. The bonding position of -NH ₂ bonded to the benzene ring indicates an arbitrary position in the ring, but its bonding position is preferably meta or para position. That is, when the bonding position of the group “R ²⁵ -G ²⁶ —” is the first position, the two bonding positions are preferably the third position and the fifth position, or the second position and the fifth position.

In the formula (DI-31-a), G ²⁷ , G ²⁸ and G ^{29 each} represent a bonding group, and each independently represents a single bond or an alkylene group having 1 to 12 carbon atoms. One or more —CH ₂ — may be substituted with —O—, —COO—, —OCO—, —CONH—, or —CH═CH—. Ring B ²¹ , Ring B ²² , Ring B ²³ and Ring B ²⁴ are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,3-dioxane-2,5-diyl group, Pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, naphthalene-1,5-diyl group, naphthalene-2,7-diyl group or anthracene-9,10-diyl group, and ring B ²¹ , Ring B ²² , ring B ^23, and ring B ²⁴ , at least one hydrogen atom may be substituted with —F or —CH ₃ , and s, t, and u are each independently an integer of 0-2. And the sum of these is 1-5, when s, t or u is 2, the two linking groups in each bracket may be the same or different, and the two rings are They may be the same or different. R ²⁶ represents a hydrogen atom, —F, —OH, an alkyl group having 1 to 30 carbon atoms, a fluorine-substituted alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, —CN, —OCH ₂ F, — Represents OCHF ₂ or —OCF _3, and at least one —CH ₂ — of the alkyl group having 1 to 30 carbon atoms is substituted with a divalent group represented by the following formula (DI-31-b). Also good.

In the formula (DI-31-b), R ²⁷ and R ²⁸ are each independently an alkyl group having 1 to 3 carbon atoms, and v is an integer of 1 to 6. Preferred examples of R ²⁶ are an alkyl group having 1 to 30 carbon atoms and an alkoxy group having 1 to 30 carbon atoms.

In the formula (DI-32) and the formula (DI-33), G ³⁰ independently represents a single bond, —CO— or —CH ₂ —, R ²⁹ independently represents a hydrogen atom or —CH ₃ , R ³⁰ independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms. At least one hydrogen atom of the benzene ring in formula (DI-33) may be substituted with an alkyl group having 1 to 20 carbon atoms or a phenyl group. A group whose bonding position is not fixed to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary. One of the two groups “-phenylene-G ³⁰ —O—” in formula (DI-32) is preferably bonded to the 3-position of the steroid nucleus and the other is bonded to the 6-position of the steroid nucleus. The bonding position of the two groups “-phenylene-G ³⁰ —O—” in the formula (DI-33) to the benzene ring is preferably the meta position or the para position, respectively, with respect to the bonding position of the steroid nucleus. In formula (DI-32) and formula (DI-33), -NH ₂ bonded to the benzene ring indicates that the binding position in the ring is optional.

In formula (DI-34) and formula (DI-35), G ³¹ independently represents —O— or an alkylene group having 1 to 6 carbon atoms, and G ³² represents a single bond or an alkylene group having 1 to 3 carbon atoms. Represents. R ³¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and at least one —CH ₂ — of the alkyl group may be replaced by —O—, —CH═CH— or —C≡C—. Good. R ³² represents an alkyl group having 6 to 22 carbon atoms, and R ³³ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. Ring B ²⁵ is a 1,4-phenylene group or a 1,4-cyclohexylene group, and r is 0 or 1. In addition, —NH ₂ bonded to the benzene ring indicates that the bonding position in the ring is arbitrary, but it is preferably independently a meta position or a para position with respect to the bonding position of G ³¹ .

Examples of the compound represented by the formula (DI-31) are shown below.

In formulas (DI-31-1) to (DI-31-11), R ³⁴ each independently represents an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, preferably 5 carbon atoms. An alkyl group having -25 or an alkoxy group having 5 to 25 carbon atoms. R ³⁵ each independently represents an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, preferably an alkyl group having 3 to 25 carbon atoms or an alkoxy group having 3 to 25 carbon atoms.

In formulas (DI-31-12) to (DI-31-17), R ³⁶ each independently represents an alkyl group having 4 to 30 carbon atoms, preferably an alkyl group having 6 to 25 carbon atoms. R ³⁷ each independently represents an alkyl group having 6 to 30 carbon atoms, preferably an alkyl group having 8 to 25 carbon atoms.

In formulas (DI-31-18) to (DI-31-43), R ³⁸ each independently represents an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, preferably 3 carbon atoms. An alkyl group having -20 carbon atoms or an alkoxy group having 3-20 carbon atoms. R ³⁹ independently represents a hydrogen atom, -F, alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, -CN, a -OCH ₂ F, -OCHF ₂ or -OCF _3, preferably Is an alkyl group having 3 to 25 carbon atoms or an alkoxy group having 3 to 25 carbon atoms. G ³³ represents an alkylene group having 1 to 20 carbon atoms.

Examples of the compound represented by the formula (DI-32) are shown below.

Examples of the compound represented by the formula (DI-33) are shown below.

Examples of the compound represented by the formula (DI-34) are shown below.

In the formula (DI-34-1) to the formula (DI-34-12), each R ⁴⁰ independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, preferably a hydrogen atom or an alkyl having 1 to 10 carbon atoms. Each of R ⁴¹ independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

Examples of the compound represented by the formula (DI-35) are shown below.
In formula (DI-35-1) ~ (DI -35-3), R 37 each independently represents an alkyl group having 6 to 30 carbon atoms, R ⁴¹ is a hydrogen atom or a carbon number 1 independently 12 alkyl groups are represented.

The compounds represented by formulas (DI-36-1) to (DI-36-8) are shown below.
In formulas (DI-36-1) to (DI-36-8), R ⁴² each independently represents an alkyl group having 3 to 30 carbon atoms.

  In the diamine and dihydrazide, suitable materials for improving each characteristic of the liquid crystal alignment film described later will be described. When importance is attached to further improving the orientation of the liquid crystal, the formula (DI-1-3), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9) ), Formula (DI-5-12), Formula (DI-5-13), Formula (DI-5-29), Formula (DI-6-7), Formula (DI-7-3), and Formula (DI-7-3) It is preferable to use a compound represented by DI-11-2). In the formula (DI-5-1), m = 2, 4 or 6 is preferable, and m = 4 is more preferable. In formula (DI-5-12), m = 2 to 6 is preferable, and m = 5 is more preferable. In formula (DI-5-13), m = 1 or 2 is preferable, and m = 1 is more preferable.

  When emphasizing improving the transmittance, formula (DI-1-3), formula (DI-2-1), formula (DI-5-1), formula (DI-5-5), formula It is preferable to use a diamine represented by (DI-5-24) and formula (DI-7-3), and a compound represented by formula (DI-2-1) is more preferable. In the formula (DI-5-1), m = 2, 4 or 6 is preferable, and m = 4 is more preferable. In formula (DI-7-3), m = 2 or 3, n = 1 or 2 are preferable, and m = 3 and n = 1 are more preferable.

  When importance is attached to improving the VHR of the liquid crystal display element, the formula (DI-2-1), the formula (DI-4-1), the formula (DI-4-2), the formula (DI-4-10) ), Formula (DI-4-15), formula (DI-4-22), formula (DI-5-28), formula (DI-5-30), and formula (DI-13-1). It is preferable to use a compound represented by formula (DI-2-1), formula (DI-5-1), and diamine represented by formula (DI-13-1). In the formula (DI-5-1), m = 1 is preferable. In the formula (DI-5-30), k = 2 is preferable.

  Increasing the relaxation rate of the residual charge (residual DC) in the liquid crystal alignment film by reducing the volume resistance value of the liquid crystal alignment film is effective as one method for preventing burn-in. When emphasizing this purpose, formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-5) -1), formula (DI-5-12), formula (DI-5-13), formula (DI-5-28), formula (DI-4-20), formula (DI-4-21), formula (DI-7-12) and a compound represented by the formula (DI-16-1) are preferably used, and the formula (DI-4-1), the formula (DI-5-1), and the formula (DI The compound represented by -5-13) is more preferable. In formula (DI-5-1), m = 2, 4 or 6 is preferable, and m = 4 is more preferable. In formula (DI-5-12), m = 2 to 6 is preferable, and m = 5 is more preferable. In formula (DI-5-13), m = 1 or 2 is preferable, and m = 1 is more preferable. In formula (DI-7-12), m = 3 or 4 is preferable, and m = 4 is more preferable.

  In each diamine, the ratio of the monoamine to the diamine may be 40 mol% or less, and a part of the diamine may be replaced with the monoamine. Such replacement can cause termination of the polymerization reaction when the polyamic acid is produced, and further progress of the polymerization reaction can be suppressed. For this reason, the molecular weight of the obtained polymer (polyamic acid or its derivative) can be easily controlled by such replacement, and for example, the coating characteristics of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. Can do. As long as the effect of the present invention is not impaired, one or more diamines may be substituted for the monoamine. Examples of the monoamine include aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n- Undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, and n-eicosylamine Is mentioned.

(Monoisocyanate)
When the monomer composition is a composition for synthesizing a polyamic acid or a derivative thereof, for example, the diamine represented by the formula (2) is included as the first monomer, and the formula (II-1) is included as the second monomer. , Formula (II-2), Formula (III-1), Formula (III-2), Formula (IV-1), Formula (IV-2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula (VIII-1), and Formula (VIII-2) In the case where it contains a compound represented by any one and further contains a non-photoreactive tetracarboxylic dianhydride or a derivative thereof, if necessary, a monoisocyanate compound may be further contained in the monomer composition. . By containing a monoisocyanate compound in the monomer composition, the terminal of the resulting polyamic acid or derivative thereof is modified, and the molecular weight is adjusted. By using this terminal-modified polyamic acid or derivative thereof, for example, the coating properties of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. It is preferable from said viewpoint that content of the monoisocyanate compound in a monomer is 1-10 mol% with respect to the total amount of the diamine and tetracarboxylic dianhydride in a monomer. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

(Combination of monomers)
As a combination of monomers in the monomer composition,
The first monomer is a diamine represented by formula (2), and the second monomer is represented by formula (II-1), formula (III-1), formula (IV-1), formula (IV-3). ), A compound (tetracarboxylic dianhydride) represented by any one of formula (V-1) and formula (VI-1),
A 1st monomer is diamine represented by Formula (2), Comprising: A 2nd monomer is Formula (II-2), Formula (III-2), Formula (IV-2), Formula (V-2). ), Formula (V-3), Formula (VI-2), Formula (VII-1), Formula (VIII-1), and Formula (VIII-2). Furthermore, as another monomer, a combination in which a non-photoreactive tetracarboxylic dianhydride or a derivative thereof is added can be exemplified. Examples of tetracarboxylic dianhydride derivatives include compounds in which a part of acid dianhydride contained in tetracarboxylic diester, tetracarboxylic diester dichloride, tetracarboxylic dianhydride compound is replaced with organic dicarboxylic acid, etc. Can do. Thereby, the structure represented by Formula (1), Formula (II-1), Formula (III-1), Formula (IV-1), Formula (IV-3), Formula (V-1), Or the structure of the part except -CO-O-CO- in the formula (VI-1), and the polyamic acid having a carbonyl group and a carboxyl group converted from -CO-O-CO- in the structural unit of the main chain, And the structure represented by Formula (1), Formula (II-2), Formula (III-2), Formula (IV-2), Formula (V-2), Formula (V-3), Formula ( VI-2), formula (VII-1), formula (VIII-1), or the structure of the portion excluding the -NH ₂ in the formula (VIII-2), and, -NH- mainly converted from -NH ₂ The polyamic acid which has in the structural unit of a chain | strand, and also the derivative of these polyamic acids can be obtained. Moreover, you may add said nonphotoreactive diamine, nonphotoreactive dihydrazide, and monoisocyanate to these combinations further.

[Polymer obtained by polymerizing monomer composition or derivative thereof]
The photoreactive polymer component contained in the liquid crystal aligning agent of the present invention comprises a polymer obtained by polymerizing the above monomer composition or a derivative thereof. Each polymer constituting the polymer component has structural units derived from the first structural unit, the second structural unit, and other monomers added as necessary, but the number and arrangement of each structural unit is The polymers may be the same or different from each other. Further, each derivative constituting the polymer component is divided into a structural unit corresponding to the first structural unit, a structural unit corresponding to the second structural unit, and a structural unit derived from other monomers added as necessary. Although it has a corresponding structural unit, the number and arrangement of each structural unit may be the same or different for each derivative.
Preferred types of the polymer obtained by polymerizing the monomer composition or its derivative include polyamic acid, polyamic acid derivative, polyester, polyamide, polysiloxane, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene-phenylmaleimide) derivative, poly A (meth) acrylate etc. can be mentioned. Examples of the polyamic acid derivative include polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide. The polymer obtained by polymerizing the monomer composition or a derivative thereof is preferably a polyamic acid or a polyamic acid derivative, and more preferably a polyamic acid.

The polyamic acid is a polymer synthesized by a polymerization reaction of a diamine represented by the formula (DI) and a tetracarboxylic dianhydride represented by the formula (AN), and is a repeating unit represented by the formula (PAA) Have By dehydrating and ring-closing the polyamic acid, a polyimide liquid crystal alignment film having a repeating unit represented by the formula (PI) can be formed. Here, for example, a diamine represented by formula (2) is used as the first monomer, and formula (II-1), formula (III-1), formula (IV-1), (IV- 3) A compound (tetracarboxylic dianhydride) represented by any one of formula (V-1) and formula (VI-1) is used, or is represented by formula (2) as the first monomer. And the second monomer as formula (II-2), formula (III-2), formula (IV-2), formula (V-2), formula (V-3), formula (VI- 2) Non-photoreactive tetracarboxylic acid as the other monomer using the compound (diamine) represented by any one of formula (VII-1), formula (VIII-1), and formula (VIII-2) By using a dianhydride, the azobenzene structure represented by the formula (1) and the formula (II) 1), Formula (II-2), Formula (III-1), Formula (III-2), Formula (IV-1), Formula (IV-2), Formula (IV-3), Formula (V-1) ), Formula (V-2), formula (V-3), formula (VI-1), formula (VI-2), formula (VII-1), formula (VIII-1), or formula (VIII-2) structure of -CO-O-CO- or portion excluding the -NH ₂ of), -CO-O-CO- or to obtain a polyamic acid having the converted structure from -NH ₂ with the structural unit of the main chain Can do.

In the formula (AN), the formula (PAA), and the formula (PI), X ¹ represents a tetravalent organic group. In Formula (DI), Formula (PAA), and Formula (PI), X ² represents a divalent organic group. The preferred ranges and examples of the tetravalent organic group represented by X ^1, formula (II-1), formula (III-1), formula (IV-1), (IV -3), formula (V-1) And the corresponding structure of the formula (VI-1) (the structure of the portion excluding -CO-O-CO-) and the corresponding tetracarboxylic dianhydride described in the column of (tetracarboxylic dianhydride) You can refer to the structure. Regarding the preferred range and specific examples of the divalent organic group in X ^2, the preferred range and specific examples of the structure represented by formula (1), formula (II-2), formula (III-2), formula (IV) -2), formula (V-2), formula (V-3), formula (VI-2), formula (VII-1), formula (VIII-1), and the corresponding structure of formula (VIII-2) Reference can be made to (structure of a portion excluding —NH ₂ ).

  The polyamic acid derivative is a compound in which a part of the polyamic acid is replaced with another atom or atomic group to change the characteristics, and is particularly preferably a compound having high solubility in a solvent used for a liquid crystal aligning agent. Examples of such polyamic acid derivatives include soluble polyimides, polyamic acid esters, and polyamic acid amides. More specifically, 1) all amino groups and carboxyl groups of polyamic acid undergo a dehydration ring-closing reaction. Polyimide, 2) Partial polyimide partially dehydrated and ring-closed, 3) Polyamic acid ester in which carboxyl group of polyamic acid is converted to ester, 4) Part of acid dianhydride contained in tetracarboxylic dianhydride compound And a polyamic acid-polyamide copolymer obtained by reacting with an organic dicarboxylic acid, and 5) polyamideimide obtained by subjecting a part or all of the polyamic acid-polyamide copolymer to a dehydration ring-closing reaction. Among these derivatives, for example, examples of polyimide include those having a structural unit represented by the above formula (PI), and examples of polyamic acid esters include structural units represented by the following formula (PAE). Things can be mentioned.

In the formula (PAE), X ¹ represents a tetravalent organic group, X ² represents a divalent organic group, and Y represents an alkyl group. The preferred ranges and examples of X ^1, X ^2, can be referred to for X ^1, X ² in the formula (PAA). For the description of Y, preferred ranges, and specific examples, the description, preferred ranges, and specific examples of the alkyl group in R ^a of the above formula (a-1) can be referred to.

(Method for synthesizing polymer from monomer composition)
Polymerization of the first monomer, the second monomer, and other monomers added as necessary, and the production of derivatives from the obtained polymer should be carried out under usual reaction conditions. Can do.
Below, when the monomer composition is composed of a monomer for synthesizing a polyamic acid or a derivative thereof, the polymerization reaction conditions for the monomer and the reaction conditions for producing the derivative will be described.
The synthesis of the polyamic acid and its derivative from the monomer composition can be performed in the same manner as the synthesis of a known polyamic acid or its derivative used for forming a polyimide film.
For example, the total amount of tetracarboxylic dianhydride is preferably 0.9 to 1.1 moles per 1 mole of diamine.

Further, when the polyamic acid obtained by polymerizing the monomer composition is used as a polyimide that is a polyamic acid derivative, the obtained polyamic acid solution is mixed with acetic anhydride, propionic anhydride, trifluoroacetic anhydride as dehydrating agents. A polyimide can be obtained by performing an imidization reaction at a temperature of 20 to 150 ° C. with an acid anhydride such as triethylamine, pyridine, collidine and the like, which are dehydrating ring-closing catalysts. Alternatively, polyamic acid is precipitated from the obtained polyamic acid solution using a large amount of poor solvent (alcohol solvent or glycol solvent such as methanol, ethanol, isopropanol), and the precipitated polyamic acid is converted into toluene, xylene, or the like. A polyimide can also be obtained by carrying out an imidization reaction at a temperature of 20 to 150 ° C. together with the above dehydrating agent and dehydrating ring closure catalyst in a solvent.
In this imidation reaction, the ratio of the dehydrating agent to the dehydrating ring-closing catalyst is preferably 0.1 to 10 (molar ratio). The total amount of the dehydrating agent and the dehydrating ring-closing catalyst is preferably 1.5 to 10 times the molar amount of the total molar amount of tetracarboxylic dianhydride used for the synthesis of the polyamic acid. The degree of imidization can be controlled by adjusting the dehydrating agent, catalyst amount, reaction temperature, and reaction time used in this imidization reaction, which allows only a part of polyamic acid to imidize in addition to polyimide. A partial polyimide can be obtained. The obtained polyimide or partial polyimide is separated from the solvent used in the reaction and can be redissolved in another solvent and used as a liquid crystal aligning agent, or used as a liquid crystal aligning agent without being separated from the solvent. You can also

  The polyamic acid ester is derived from a method of synthesis by reacting a polyamic acid obtained by polymerizing a monomer composition with a hydroxyl group-containing compound, a halide, an epoxy group-containing compound, or the like, or a tetracarboxylic dianhydride. It can be obtained by a method of synthesis by reacting tetracarboxylic acid diester or tetracarboxylic acid diester dichloride with diamine. Tetracarboxylic acid diesters derived from tetracarboxylic dianhydride can be obtained by, for example, reacting tetracarboxylic dianhydride with 2 equivalents of alcohol to cause ring opening, and tetracarboxylic acid diester dichloride is obtained by reacting with tetracarboxylic acid. It can be obtained by reacting the diester with 2 equivalents of a chlorinating agent (for example, thionyl chloride). The polyamic acid ester may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist.

  The liquid crystal aligning agent for photo-alignment of the present invention may contain only one type of these polymers or derivatives thereof (particularly polyamic acid or derivatives thereof), or may contain two or more types.

  The molecular weight of the polyamic acid or derivative thereof is preferably 7,000 to 500,000 and more preferably 10,000 to 200,000 in terms of polystyrene-equivalent weight average molecular weight (Mw). The molecular weight of the polyamic acid or derivative thereof can be determined from measurement by gel permeation chromatography (GPC) method.

  The polyamic acid obtained by polymerizing the monomer composition or a derivative thereof, and the derivative produced from the polyamic acid are obtained by precipitating with a large amount of a poor solvent, the solid content obtained by IR (infrared spectroscopy), NMR (nuclear magnetic resonance) Its presence can be confirmed by analyzing in (Analysis). Moreover, the extract by the organic solvent of the decomposition product of polyamic acid or its derivative with strong alkali aqueous solution, such as KOH and NaOH, is obtained by GC (gas chromatography), HPLC (high performance liquid chromatography) or GC-MS (gas chromatography mass spectrometry). By analyzing, the monomer used can be confirmed.

<Preferred embodiment of polymer component>
The liquid crystal aligning agent of the present invention may contain one kind of photoreactive polymer component obtained from a single monomer composition, or two or more kinds of photoreactive polymers having different monomer composition compositions. A component may be included. When placing importance on the liquid crystal alignment property of the liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention, the photoreactive polymer component is preferably composed of polyamic acid or a derivative thereof, and the liquid crystal aligning agent is polyamic acid or It is preferable to include two or more kinds of photoreactive polymer components made of the derivatives.
In the present specification, a liquid crystal aligning agent containing only one type of polymer component may be referred to as a single layer type liquid crystal aligning agent. Moreover, the liquid crystal aligning agent containing 2 or more types of polymer components may be called a blend type liquid crystal aligning agent. The plurality of polymer components in the blend type liquid crystal aligning agent may be at least one photoreactive polymer component, and may contain a non-photoreactive polymer component. Here, the “non-photoreactive polymer component” is a polymer component made of a polymer obtained by polymerizing a monomer composition or a derivative thereof, and the monomer composition is made of a non-photoreactive monomer. Say.

  When emphasizing the balance between the storage stability of the liquid crystal aligning agent, the printability of the liquid crystal aligning agent on the display element substrate, and the characteristics of the liquid crystal alignment film to be formed, a blend type liquid crystal aligning agent is preferable. As a preferred example of the blend-type liquid crystal aligning agent, a first photoreactive polymer component obtained from a monomer composition containing at least a first monomer and a second monomer, and at least a first monomer and a second monomer A blend type liquid crystal aligning agent comprising a second photoreactive polymer component obtained from a monomer composition having a composition different from that of the monomer composition used in the first photoreactive polymer. And a blend type liquid crystal aligning agent in which a photoreactive polymer component obtained from a monomer composition containing at least a first monomer and a second monomer and a non-photoreactive polymer component are combined. Here, the non-photoreactive polymer component is preferably obtained from a monomer composition containing a monomer for synthesizing a polyamic acid or a derivative thereof. For preferred ranges and specific examples of tetracarboxylic dianhydrides, diamines, and other monomers used as monomers for non-photoreactive polymer components, see (Non-photoreactive tetracarboxylic dianhydrides), (Non-photoreactive diamines) Reference can also be made to the descriptions in the columns (non-photoreactive dihydrazide) and (monoisocyanate).

When such two types of polymer components are used, for example, a polymer component having a performance excellent in liquid crystal alignment ability is selected on the one hand, and a performance superior in improving the electrical characteristics of the liquid crystal display element on the other hand. There is an aspect of selecting a polymer component having In this case, by controlling the structure and molecular weight of the polymer contained in each polymer component, a liquid crystal aligning agent in which these polymer components are dissolved in a solvent is applied to a substrate and preliminarily dried as described later. In the process of forming a thin film, the polymer component having excellent performance in liquid crystal alignment ability is segregated in the upper layer of the thin film, and the polymer component having excellent performance in improving the electrical characteristics of the liquid crystal display element is segregated in the lower layer of the thin film. be able to. For this, a phenomenon can be applied in which, in the mixed polymer component, a polymer component composed of a polymer having a small surface energy is separated into an upper layer, and a polymer component composed of a polymer having a large surface energy is separated into a lower layer. The confirmation of such layer separation is that the surface energy of the formed liquid crystal alignment film is the same as the surface energy of the film formed by the liquid crystal aligning agent containing only the polymer component intended to be segregated in the upper layer, or It can be confirmed by the close value.
As a method for expressing layer separation, it is also possible to reduce the molecular weight of the polymer in the polymer component to be segregated in the upper layer.
Moreover, in the liquid crystal aligning agent which consists of mixing of polyamic acids, layer separation can also be expressed by comprising the polymer component to segregate to an upper layer with a polyimide.

  The first monomer and the second monomer may be contained in the monomer composition for the polymer component segregated in the upper layer of the thin film, or may be contained in the monomer composition for the polymer component segregated in the lower layer of the thin film. It may also be included in both monomer compositions. For preferred ranges and specific examples of the first monomer and the second monomer for obtaining polyamic acid or a derivative thereof, the descriptions in the columns of [First monomer] and [Second monomer] can be referred to. .

When the polymer component segregated on the upper layer of the thin film is made of polyamic acid or a derivative thereof, the tetracarboxylic dianhydride used for the synthesis is limited from the known tetracarboxylic dianhydrides exemplified above. You can choose without.
For example, tetracarboxylic dianhydride has formula (AN-1-1), formula (AN-2-1), formula (AN-3-1), formula (AN-4-5), and formula (AN The compound represented by -4-17) is preferable, and the formula (AN-4-17) is more preferable. In formula (AN-4-17), m = 4 or 8 is preferable, and m = 8 is more preferable.

Further, when the polymer component segregated on the upper layer of the thin film is composed of polyamic acid or a derivative thereof, as the non-photoreactive diamine and non-photoreactive dihydrazide used for the synthesis, from the known diamines and dihydrazides exemplified above You can select without limitation.
For example, as the non-photoreactive diamine and non-photoreactive dihydrazide, the formula (DI-4-1), the formula (DI-4-13), the formula (DI-4-15), the formula (DI-5-1) It is preferable to use a compound represented by formula (DI-7-3) and formula (DI-13-1). Among these, it is more preferable to use a compound represented by the formula (DI-4-13), the formula (DI-4-15), the formula (DI-5-1), and the formula (DI-13-1). In formula (DI-5-1), m = 1, 2 or 4 is preferable, and m = 4 is more preferable. In the formula (DI-7-3), m = 3 and n = 1 are preferable.
The non-photoreactive diamine used in the synthesis preferably contains 30 mol% or more of aromatic diamine, more preferably 50 mol% or more, based on the total amount of nonphotoreactive diamine.

When the polymer component segregated in the lower layer of the thin film is composed of polyamic acid or a derivative thereof, the tetracarboxylic dianhydride used for the synthesis is limited from the known tetracarboxylic dianhydrides exemplified above. You can choose without.
For example, tetracarboxylic dianhydride has formula (AN-1-1), formula (AN-1-13), formula (AN-2-1), formula (AN-3-2), and formula (AN The compound represented by -4-21) is preferable, and the formula (AN-1-1), the formula (AN-2-1), and the formula (AN-3-2) are more preferable.
The tetracarboxylic dianhydride used for the synthesis preferably contains 10 mol% or more, more preferably 30 mol% or more of the aromatic tetracarboxylic dianhydride in the total amount of tetracarboxylic dianhydride.

When the polymer component segregated in the lower layer of the thin film is composed of polyamic acid or a derivative thereof, the diamine and dihydrazide used for the synthesis can be selected from the known diamines exemplified above.
For example, diamine and dihydrazide may be represented by the formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-18), formula (DI-4-19). ), Formula (DI-5-9), formula (DI-5-28), formula (DI-5-30), formula (DI-13-1), and formula (DIH-2-1). Are preferred. Especially, it is represented by formula (DI-4-1), formula (DI-4-18), formula (DI-4-19), formula (DI-5-9), and formula (DI-13-1). Are more preferred. In formula (DI-5-30), a diamine in which k = 2 is preferable.
The diamine used for the synthesis preferably contains 30 mol% or more of aromatic diamine, more preferably 50 mol% or more, based on the total diamine.

  The polymer component comprising a polyamic acid or derivative thereof segregated on the upper layer of the thin film is 5% to 50% by weight based on the total amount of the polymer component and the polymer component comprising polyamic acid or derivative thereof segregated on the lower layer of the thin film. 10 wt% to 40 wt% is more preferable.

<Other components of liquid crystal aligning agent>
The liquid crystal aligning agent includes at least a polymer component (photoreactive polymer component) having a structural unit including a photoreactive structure, and may include other components. Examples of other components include a polymer component (non-photoreactive polymer component) having no structural unit including a photoreactive structure, a solvent, and an additive.
For the description of the non-photoreactive polymer component, reference can be made to the corresponding description in the section <Preferred embodiment of polymer component>.

[solvent]
The liquid crystal aligning agent of the present invention may further contain a solvent from the viewpoint of adjusting the coating property of the liquid crystal aligning agent and the concentration of the polymer component. The solvent can be applied without any particular limitation as long as it has the ability to dissolve the polymer constituting the polymer component. As the solvent, for example, a solvent usually used in the production process of polymer components such as polyamic acid and soluble polyimide and various applications can be used, and can be appropriately selected according to the purpose of use. The solvent may be one type or a mixed solvent of two or more types.

Examples of the solvent include a parent solvent for polyamic acid or a derivative thereof, and other solvents for improving coating properties.
For example, an aprotic polar organic solvent which is a parent solvent for polyamic acid or a derivative thereof can be used. Specifically, N-methyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methyl Lactones such as propionamide, N, N-dimethylacetamide, dimethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, diethylacetamide, N, N-dimethylisobutyramide, γ-butyrolactone, γ-valerolactone, etc. Can be mentioned.
Examples of other solvents for improving coating properties include diisobutyl ketone, alkyl lactate, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol, diisobutyl carbinol, tetralin, Isophorone, ethylene glycol monoalkyl ether such as ethylene glycol monobutyl ether, diethylene glycol monoalkyl ether such as diethylene glycol monoethyl ether, diethylene glycol dialkyl ether such as diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, ethylene glycol monoalkyl or phenyl Acetate, triethylene glycol monoalkyl ether, propylene glycol Propylene glycol monoalkyl ethers such as nomethyl ether and 1-butoxy-2-propanol, dialkyl malonates such as diethyl malonate, dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, and ester compounds such as acetates Can be mentioned.
Among these, the solvent for the liquid crystal aligning agent is N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, γ-valerolactone, diisobutylketone, 4-methyl-2-pentanol, diisobutylcarbinol, More preferred are ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, 1-butoxy-2-propanol, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether and butyl cellosolve acetate.

For example, when the liquid crystal aligning agent which used the polyamic acid for the photoreactive polymer component contains a solvent, it is preferable that the density | concentration of the polyamic acid in a liquid crystal aligning agent is 0.1 to 40 weight%. When this liquid crystal aligning agent is applied to the substrate, an operation of diluting the contained polyamic acid with a solvent in advance may be required to adjust the film thickness.
The solid content concentration in the liquid crystal aligning agent is not particularly limited, and it is preferable to select appropriately according to the coating method of the liquid crystal aligning agent. In order to suppress unevenness and pinholes at the time of application, it is usually preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight, based on the total amount of the liquid crystal alignment agent.

The viscosity of the liquid crystal aligning agent varies depending on the method used for coating the liquid crystal aligning agent, the type and concentration of the polymer contained as the polymer component, the type and concentration of the solvent, and the like. Is preferably 5 to 100 mPa · s, more preferably 10 to 80 mPa · s. Thereby, the liquid crystal alignment film can be formed with a sufficient film thickness while suppressing printing unevenness. Moreover, when apply | coating a liquid crystal aligning agent by spin coating, it is preferable that the viscosity of a liquid crystal aligning agent is 5-200 mPa * s, and it is more preferable that it is 10-100 mPa * s. When applying a liquid crystal aligning agent with an inkjet coating device, the viscosity of the liquid crystal aligning agent is preferably 5 to 50 mPa · s, and more preferably 5 to 20 mPa · s.
The viscosity of the liquid crystal aligning agent is measured by a rotational viscosity measurement method, and is measured (measurement temperature: 25 ° C.) using, for example, a rotational viscometer (TVE-20L type manufactured by Toki Sangyo Co., Ltd.).

[Additive]
The liquid crystal aligning agent of the present invention may further contain various additives. Various additives can be selected and used depending on the purpose in order to improve various properties of the alignment film. An example is shown below.

(Alkenyl-substituted nadiimide compound)
For example, the liquid crystal aligning agent of the present invention may further contain an alkenyl-substituted nadiimide compound for the purpose of stabilizing the electrical characteristics of the liquid crystal display element over a long period of time. An alkenyl substituted nadiimide compound may be used by 1 type, and may use 2 or more types together. For the above purpose, the content of the alkenyl-substituted nadiimide compound is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, and more preferably 1 to 20% by weight with respect to the polyamic acid or derivative thereof. More preferably. The alkenyl-substituted nadiimide compound is preferably a compound that can be dissolved in a solvent that dissolves the polyamic acid or derivative thereof used in the present invention. Preferred alkenyl-substituted nadiimide compounds include alkenyl-substituted nadiimide compounds disclosed in JP-A-2008-096979, JP-A-2009-109987, and JP-A-2013-242526. Particularly preferred alkenyl-substituted nadiimide compounds include bis {4- (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboximido) phenyl} methane, N, N′-m-xylylene- Bis (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboximide), N, N′-hexamethylene-bis (allylbicyclo [2.2.1] hept-5-ene -2,3-dicarboximide).

(Compound having a radically polymerizable unsaturated double bond)
For example, the liquid crystal aligning agent of the present invention may further contain a compound having a radical polymerizable unsaturated double bond for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. The compound having a radically polymerizable unsaturated double bond may be one type of compound or two or more types of compounds. The compound having a radical polymerizable unsaturated double bond does not include an alkenyl-substituted nadiimide compound. Preferred compounds having a radically polymerizable unsaturated double bond include N, N′-methylenebisacrylamide, N, N′-dihydroxyethylene-bisacrylamide, ethylenebisacrylate, and 4,4′-methylenebis ( N, N-dihydroxyethylene acrylate aniline), triallyl cyanurate, and other radicals disclosed in JP2009-109987A, JP2013-242526A, International Publication 2014/119682, International Publication 2015/201514 The compound which has a polymerizable unsaturated double bond is mentioned. The content of the compound having a radically polymerizable unsaturated double bond is preferably 1 to 50% by weight, more preferably 1 to 30% by weight based on the polyamic acid or its derivative for the above purpose. preferable.

(Oxazine compound)
For example, the liquid crystal aligning agent of this invention may further contain the oxazine compound from the objective of stabilizing the electrical property in a liquid crystal display element for a long period of time. The oxazine compound may be one type of compound or two or more types of compounds. The content of the oxazine compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and more preferably 1 to 20% by weight with respect to the polyamic acid or derivative thereof for the above purpose. More preferably.

  The oxazine compound is soluble in a solvent for dissolving the polyamic acid or a derivative thereof, and in addition, an oxazine compound having ring-opening polymerizability is preferable. Preferred oxazine compounds include oxazine compounds represented by formula (OX-3-1), formula (OX-3-9), and formula (OX-3-10), in addition to JP-A 2007-286597, Examples thereof include oxazine compounds disclosed in JP2013-242526A.

(Oxazoline compound)
For example, the liquid crystal aligning agent of this invention may further contain the oxazoline compound from the objective of stabilizing the electrical property in a liquid crystal display element for a long period of time. An oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one type of compound or two or more types of compounds. The content of the oxazoline compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and more preferably 1 to 20% by weight with respect to the polyamic acid or a derivative thereof for the above purpose. More preferably. Preferred oxazoline compounds include oxazoline compounds disclosed in JP 2010-048772 A and JP 2013-242526 A. More preferred is 1,3-bis (4,5-dihydro-2-oxazolyl) benzene.

(Epoxy compound)
For example, the liquid crystal aligning agent of the present invention further contains an epoxy compound for the purpose of stabilizing the electrical characteristics in the liquid crystal display element for a long period of time, the purpose of improving the hardness of the film, or the purpose of improving the adhesion with the sealing agent. It may be. The epoxy compound may be one type of compound or two or more types of compounds. The content of the epoxy compound is preferably 0.1 to 50% by weight, more preferably 1 to 20% by weight, more preferably 1 to 10% by weight with respect to the polyamic acid or derivative thereof for the above purpose. More preferably.
As the epoxy compound, various compounds having one or more epoxy rings in the molecule can be used.
For the purpose of improving the hardness of the film or improving the adhesion to the sealant, a compound having two or more epoxy rings in the molecule is preferable, and a compound having three or four is more preferable.
As an epoxy compound, the epoxy compound currently disclosed by Unexamined-Japanese-Patent No. 2009-175715, Unexamined-Japanese-Patent No. 2013-242526, Unexamined-Japanese-Patent No. 2006-170409, and international publication 2017/217413 is mentioned. Preferred epoxy compounds include N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxy. Silane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, (3,3 ′, 4,4′-diepoxy) bicyclohexyl, 1,4-butanediol glycidyl ether, isocyanuric acid tris (2,3- Epoxypropyl), 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylenediamine.
In addition to the above, an oligomer or polymer having an epoxy ring can also be added. As the oligomer or polymer having an epoxy ring, the oligomer or polymer disclosed in JP2013-242526A can be used.

(Silane compound)
For example, the liquid crystal aligning agent of the present invention may further contain a silane compound for the purpose of improving the adhesion between the substrate and the sealing agent. The content of the silane compound is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, more preferably 0.5% to 0.5% by weight based on the above-mentioned purpose. More preferably, it is 10 weight%.
As a silane coupling agent, the silane coupling agent currently disclosed by Unexamined-Japanese-Patent No. 2013-242526, Unexamined-Japanese-Patent No. 2015-212807, Unexamined-Japanese-Patent No. 2018-173545, and international publication 2018/181565 can be used.
Preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, paraaminophenyltrimethoxysilane, and 3 -Aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-trimethoxypropyl succinic acid, 3-triethoxypropyl succinic acid, 3-isocyanatopropyltriethoxysilane, 3-ureidopropyltriethoxysilane Can be mentioned.

  In addition to the additives described above, a compound having a cyclocarbonate group, a compound having a hydroxyalkylamide moiety or a hydroxyl group is added for the purpose of increasing the strength of the alignment film or stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. You can also Specific examples of the compound include those disclosed in JP-A-2006-118753 and International Publication No. 2017/110976. Preferred compounds include the following formulas (HD-1) to (HD-4). These compounds are preferably 0.5 to 50% by weight, more preferably 1 to 30% by weight, and still more preferably 1 to 10% by weight based on the polyamic acid or derivative thereof.

  In addition, an antistatic agent can be used when improvement in antistatic is required, and an imidization catalyst can be used when imidization proceeds at a low temperature. As an imidation catalyst, the imidation catalyst currently disclosed by Unexamined-Japanese-Patent No. 2013-242526 is mentioned.

Next, the liquid crystal alignment film of the present invention will be described.
The liquid crystal alignment film of the present invention is formed by the liquid crystal aligning agent for photo-alignment of the present invention.
For the description of the liquid crystal aligning agent for photo-alignment of the present invention, the preferred range, and specific examples, the description in the column of the liquid crystal aligning agent for photo-alignment can be referred to.
Below, an example of the formation method of the liquid crystal aligning film by the liquid crystal aligning agent (liquid crystal aligning agent) for photo-alignment of this invention is demonstrated.
The liquid crystal alignment film of the present invention can be obtained by an ordinary method for producing a liquid crystal alignment film from a liquid crystal aligning agent. The liquid crystal alignment film of the present invention includes, for example, a step of forming a coating film of the liquid crystal alignment agent of the present invention, a step of heating and drying the coating film to form a liquid crystal alignment agent film, Can be obtained through a step of applying anisotropy (orientation step) and a step of heating and baking a film of a liquid crystal aligning agent to which anisotropy is provided (heating and baking step). During this heating and firing, in the present invention, the first constituent unit of the polymer or its derivative constituting the polymer chain of the liquid crystal alignment film undergoes a chemical reaction, and the photoreactive group for photoalignment disappears, and the film Overall, the number of photoreactive groups is reduced or no photoreactive groups are present. Therefore, the formed liquid crystal alignment film hardly generates radicals even when exposed to strong light, and exhibits high stability to light. At this time, the second structural unit of the polymer or derivative thereof retains the structure immediately after the photo-alignment treatment without causing a chemical reaction, so that the structure becomes anisotropic to the polymer main chain. Contribute effectively. As a result, the formed liquid crystal alignment film exhibits good liquid crystal alignment in addition to high stability to light.

A coating film can be formed by apply | coating the liquid crystal aligning agent of this invention to the board | substrate in a liquid crystal display element similarly to preparation of a normal liquid crystal aligning film. The substrate may be provided with electrodes such as ITO (Indium Tin Oxide), IZO (In ₂ O ₃ —ZnO), IGZO (In—Ga—ZnO ₄ ) electrodes, color filters, etc. Examples include substrates made of acrylic, polycarbonate, polyimide, and the like.

  As a method for applying a liquid crystal aligning agent to a substrate, a spinner method, a printing method, a dipping method, a dropping method, an ink jet method and the like are generally known. These methods are similarly applicable in the present invention.

  As the heat drying step, a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, and the like are generally known. The heat drying step is preferably performed at a temperature within a range where the solvent can be evaporated, and more preferably at a temperature relatively lower than the temperature in the heat baking step. Specifically, the heat drying temperature is preferably in the range of 30 ° C to 150 ° C, and more preferably in the range of 50 ° C to 120 ° C.

The heat-firing step can be performed, for example, under conditions necessary for the polyamic acid or the derivative constituting the photoreactive polymer component to exhibit a dehydration / ring-closing reaction. As for the baking of the coating film, a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, and the like are generally known. These methods are equally applicable in the present invention. The heating temperature is preferably 40 to 300 ° C, more preferably 100 to 300 ° C, still more preferably 120 to 280 ° C, and still more preferably 150 to 250 ° C. The heating time is preferably 1 minute to 3 hours, more preferably 5 minutes to 1 hour, and even more preferably 15 minutes to 45 minutes. It is desirable to adjust the heating time according to the heating temperature. For example, when the heating temperature is 40 to 180 ° C., the heating time is preferably 10 minutes to 3 hours, and when the heating temperature is 180 to 300 ° C. It is preferably 1 minute to 1 hour. Among these, it is more preferable that the heating temperature is 150 to 280 ° C. and the heating time is 10 minutes to 1 hour, and the heating temperature is 180 to 250 ° C. and the heating time is 15 minutes to 45 from the point that the reaction efficiency can be increased. More preferably, it is minutes.
Further, the heating and baking can be performed a plurality of times at different temperatures. At this time, a plurality of heating devices set to different temperatures may be used, or may be performed while sequentially changing to different temperatures using one heating device. When performing baking twice at different temperatures, the first time is preferably 90 to 180 ° C., and the second time is preferably 185 ° C. or more. Moreover, it can bake by changing temperature from low temperature to high temperature. When baking by changing temperature, 90-180 degreeC is preferable for initial temperature. The final temperature is preferably 185 to 300 ° C, more preferably 190 to 230 ° C.

  In the method for forming a liquid crystal alignment film of the present invention, a known photo-alignment method is suitably used as a means for imparting anisotropy to a thin film in order to align the liquid crystal in one direction with respect to the horizontal and / or vertical direction. be able to.

  The method for forming the liquid crystal alignment film of the present invention by the photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using the photo-alignment method imparts anisotropy to the thin film by irradiating the thin film after heating and drying the coating with linearly polarized light or non-polarized light. It can be formed by heating and baking. Alternatively, it can be formed by irradiating the thin film with linearly polarized light or non-polarized light after the coating film is heated and dried and heated and fired. From the viewpoint of orientation, the radiation irradiation step is preferably performed before the heating and baking step.

  Furthermore, in order to raise the liquid crystal aligning ability of a liquid crystal aligning film, a linearly polarized light or non-polarized light can be irradiated while heating a coating film. Irradiation may be performed in a step of heating and drying the coating film or a step of heating and baking, or may be performed between the heating and drying step and the heating and baking step. The heating and drying temperature in this step is preferably in the range of 30 ° C to 150 ° C, and more preferably in the range of 50 ° C to 120 ° C. Moreover, it is preferable that the heat-firing temperature in this process is the range of 30 degreeC-300 degreeC, Furthermore, it is preferable that it is the range of 50 degreeC-250 degreeC.

  As the radiation, for example, ultraviolet light or visible light including light having a wavelength of 150 to 800 nm can be used, but ultraviolet light including light of 300 to 400 nm is preferable. Further, linearly polarized light or non-polarized light can be used. These lights are not particularly limited as long as they can impart liquid crystal alignment ability to the thin film, but linearly polarized light is preferable when it is desired to develop a strong alignment regulating force for liquid crystals.

The liquid crystal alignment film of the present invention can exhibit high liquid crystal alignment ability even with low energy light irradiation. Dose of linearly polarized light in the irradiation step is preferably from 0.05~20J / cm ^2, more preferably 0.5~10J / cm ^2. The wavelength of linearly polarized light is preferably 200 to 400 nm, and more preferably 300 to 400 nm. Although the irradiation angle with respect to the film surface of linearly polarized light is not particularly limited, it is preferable from the viewpoint of shortening the alignment processing time that it is as perpendicular as possible to the film surface in order to develop a strong alignment regulating force for the liquid crystal. The liquid crystal alignment film of the present invention can align liquid crystal in a direction perpendicular to the polarization direction of linearly polarized light by irradiating linearly polarized light.

  The light source used in the process of irradiating linearly polarized light or non-polarized light includes ultra-high pressure mercury lamp, high pressure mercury lamp, low pressure mercury lamp, deep UV lamp, halogen lamp, metal halide lamp, high power metal halide lamp, xenon lamp, mercury A xenon lamp, an excimer lamp, a KrF excimer laser, a fluorescent lamp, an LED lamp, a sodium lamp, a microwave excitation electrodeless lamp, and the like can be used without limitation.

  The liquid crystal alignment film of the present invention can be suitably obtained by a method that further includes steps other than the steps described above. For example, the liquid crystal alignment film of the present invention does not require a process of cleaning the film after baking or radiation irradiation with a cleaning liquid, but a cleaning process can be provided for convenience of other processes.

  Examples of the cleaning method using the cleaning liquid include brushing, jet spray, steam cleaning, and ultrasonic cleaning. These methods may be performed alone or in combination. The cleaning liquid is pure water, various alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, aromatic hydrocarbons such as benzene, toluene, xylene, halogen solvents such as methylene chloride, and ketones such as acetone and methyl ethyl ketone. Although it can be used, it is not limited to these. Of course, these cleaning liquids are sufficiently purified and have few impurities. Such a cleaning method can also be applied to the cleaning step in the formation of the liquid crystal alignment film of the present invention.

In order to enhance the liquid crystal alignment ability of the liquid crystal alignment film of the present invention, annealing treatment with heat or light can be used before or after the heating and baking step or before or after irradiation with polarized or non-polarized radiation. In the annealing treatment, the annealing temperature is 30 to 180 ° C., preferably 50 to 150 ° C., and the time is preferably 1 minute to 2 hours. Examples of the annealing light used for the annealing treatment include a UV lamp, a fluorescent lamp, and an LED lamp. The light irradiation amount is preferably 0.3 to 10 J / cm ² .

  Although the film thickness of the liquid crystal aligning film of this invention is not specifically limited, It is preferable that it is 10-300 nm, and it is more preferable that it is 30-150 nm. The film thickness of the liquid crystal alignment film of the present invention can be measured by a known film thickness measuring device such as a step meter or an ellipsometer.

  The liquid crystal alignment film of the present invention is particularly characterized by having a large alignment anisotropy. The magnitude of such anisotropy can be evaluated by a method using polarized IR described in JP-A-2005-275364. It can also be evaluated by a method using ellipsometry. Specifically, the retardation value of the liquid crystal alignment film can be measured by a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of orientation of the polymer main chain. That is, a polymer film having a large retardation value has a large degree of alignment, and when used as a liquid crystal alignment film, a liquid crystal alignment film having a larger anisotropy has a large alignment regulating force on the liquid crystal composition. It is done.

  The liquid crystal alignment film of the present invention can be suitably used for a horizontal electric field type liquid crystal display element. When used in a horizontal electric field type liquid crystal display element, the smaller the Pt angle and the higher the liquid crystal alignment ability, the higher the black display level in the dark state and the better the contrast. The Pt angle is preferably 0.1 ° or less.

  The liquid crystal alignment film of the present invention can be used for alignment control of liquid crystal compositions for liquid crystal displays such as smartphones, tablets, vehicle monitors, and televisions. In addition to the alignment use of the liquid crystal composition for liquid crystal displays, it can be used for alignment control of optical compensation materials and all other liquid crystal materials. Moreover, since the liquid crystal aligning film of this invention has big anisotropy, it can be used independently for an optical compensation material use.

Next, the liquid crystal display element of the present invention will be described.
The liquid crystal display element of the present invention is characterized by having the liquid crystal alignment film of the present invention. For the description of the liquid crystal alignment film of the present invention and the method for forming the same, the preferred range, and specific examples, the description in the column of the liquid crystal alignment film can be referred to.
In the liquid crystal display element of the present invention, since the liquid crystal alignment film is the liquid crystal alignment film of the present invention, a high voltage holding ratio is maintained even when a high-brightness backlight is mounted, and high display quality can be realized. . In addition, the liquid crystal alignment film exhibits excellent liquid crystal alignment properties, and a high contrast and clear bright / dark display can be realized.
The liquid crystal display element of the present invention will be described in detail. The present invention is formed on a pair of substrates disposed opposite to each other, an electrode formed on one or both of the surfaces opposed to each of the pair of substrates, and a surface opposed to each of the pair of substrates. A liquid crystal display element comprising: a liquid crystal alignment film formed; a liquid crystal layer formed between the pair of substrates; a pair of polarizing films disposed so as to sandwich the counter substrate; a backlight; and a driving device. The liquid crystal alignment film is constituted by the liquid crystal alignment film of the present invention.

  The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. Examples of such electrodes include ITO and metal vapor deposition films. Further, the electrode may be formed on the entire surface of one surface of the substrate, or may be formed in a desired shape that is patterned, for example. Examples of the desired shape of the electrode include a comb shape or a zigzag structure. The electrode may be formed on one of the pair of substrates, or may be formed on both substrates. The form of electrode formation differs depending on the type of liquid crystal display element. For example, in the case of an IPS type liquid crystal display element (lateral electric field type liquid crystal display element), an electrode is disposed on one of the pair of substrates, and the other liquid crystal display elements In this case, electrodes are disposed on both of the pair of substrates. The liquid crystal alignment film is formed on the substrate or electrode.

  In the case of a homogeneous alignment liquid crystal display element (for example, IPS, FFS, etc.), as a configuration, at least the backlight from the backlight side, the first polarizing film, the first substrate, the first liquid crystal alignment film, the liquid crystal layer, A second substrate and a second polarizing film, wherein the polarizing axis of the polarizing film intersects the polarizing axis of the first polarizing film (polarization absorption direction) and the polarizing axis of the second polarizing film (preferably Are orthogonal to each other. At this time, the first polarizing film can be installed so that the deflection axis and the liquid crystal alignment direction are parallel or orthogonal. A liquid crystal display element installed so that the deflection axis of the first polarizing film and the liquid crystal alignment direction are parallel to each other is called an O-mode, and a liquid crystal display element installed so as to be orthogonal is called an E-mode. The liquid crystal alignment film of the present invention can be applied to both the O-mode and the E-mode, and can be selected depending on the purpose.

  Many photoisomerizable materials use dichroic compounds. Therefore, the polarization axis of polarized light to be irradiated to add anisotropy to the liquid crystal aligning agent is aligned in parallel with the polarization axis of polarized light from the polarizing film disposed on the backlight side (the liquid crystal aligning agent of the present invention When used, the O-mode arrangement) increases the transmittance in the light absorption wavelength region of the liquid crystal alignment film. Therefore, the transmittance of the liquid crystal display element can be further improved.

  The liquid crystal layer is formed in such a manner that the liquid crystal composition is sandwiched between the pair of substrates facing each other on which the liquid crystal alignment film is formed. In the formation of the liquid crystal layer, a spacer such as fine particles or a resin sheet that is interposed between the pair of substrates to form an appropriate interval can be used as necessary.

  As a method for forming a liquid crystal layer, a vacuum injection method and an ODF (One Drop Fill) method are known.

  In the vacuum injection method, a gap (cell gap) is provided so that the liquid crystal alignment film surfaces face each other, and a sealing agent is printed and the substrates are attached to each other, leaving a liquid crystal injection port. A liquid crystal is injected and filled into the cell gap defined by the substrate surface and the sealing agent by using a vacuum differential pressure, and then the injection port is sealed to manufacture a liquid crystal display element.

  In the ODF method, a sealant is printed on the outer periphery of one liquid crystal alignment film surface of a pair of substrates, the liquid crystal is dropped on a region inside the sealant, and then the other substrate so that the liquid crystal alignment film surfaces face each other. Stick together. Then, the liquid crystal is spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant, thereby manufacturing a liquid crystal display element.

  In addition to the UV curable type, a thermosetting type is also known as a sealant used for bonding substrates. The sealing agent can be printed by, for example, a screen printing method.

  The liquid crystal composition is not particularly limited, and various liquid crystal compositions having a positive or negative dielectric anisotropy can be used. Preferred liquid crystal compositions having positive dielectric anisotropy include Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent Laid-Open No. 5-501735, Japanese Patent Laid-Open No. 8-157826, Japanese Patent Laid-Open No. 8-231960, and Japanese Patent Laid-Open No. 9-93. No. 241644 (EP88272A1), JP-A-9-302346 (EP806466A1), JP-A-8-199168 (EP722998A1), JP-A-9-235552, JP-A-9-255958, JP-A-9-241463. (EP885271A1), JP-A-10-204016 (EP844229A1), JP-A-10-204436, JP-A-10-231482, JP-A-2000-087040, JP-A-2001-48822, etc. Examples of liquid crystal compositions disclosed It is.

  As preferable examples of the liquid crystal composition having the negative dielectric anisotropy, JP-A-57-114532, JP-A-2-4725, JP-A-4-222485, and JP-A-8-40953. JP-A-8-104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-236990, JP-A-10-236992, JP 10-236993 A, JP 10-236994 A, JP 10-237000 A, JP 10-237004 A, JP 10-237024 A, JP 10-237035 A, JP 10-10370 A. -237075, JP-A-10-237076, JP-A-10-237448 (EP96726) A1), JP-A-10-287874, JP-A-10-287875, JP-A-10-291945, JP-A-11-029581, JP-A-11-080049, JP-A-2000-256307 JP, 2001-019965, JP, 2001-072626, JP, 2001-192657, JP, 2010-037428, International publication 2011/024666, International publication 2010/072370, Special table 2010-537010. And the liquid crystal composition disclosed in Japanese Patent Application Laid-Open No. 2012-0777201 and Japanese Patent Application Laid-Open No. 2009-084362.

  One or more optically active compounds may be added to a liquid crystal composition having a positive or negative dielectric anisotropy.

  Further, for example, the liquid crystal composition used in the liquid crystal display element of the present invention may further contain an additive from the viewpoint of improving the orientation. Such additives are photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, antifoaming agents, polymerization initiators, polymerization inhibitors, and the like. Preferred photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, antifoaming agents, polymerization initiators, polymerization inhibitors include oxazine compounds disclosed in JP2013-242526A Is mentioned.

  A polymerizable compound can be mixed with the liquid crystal composition in order to be adapted to a liquid crystal display element in a PSA (polymer sustained alignment) mode. Preferred examples of the polymerizable compound are compounds having a polymerizable group such as acrylate, methacrylate, vinyl compound, vinyloxy compound, propenyl ether, epoxy compound (oxirane, oxetane), vinyl ketone and the like. Preferred compounds include those disclosed in JP2013-242526A.

  Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Measurement method and evaluation method [ Measurement of weight average molecular weight (Mw)]
The weight average molecular weight of the polyamic acid was determined by GPC method using a 2695 separation module / 2414 differential refractometer (manufactured by Waters) and converted to polystyrene. The sample used for the measurement was a polyamic acid obtained by mixing a phosphoric acid-DMF mixed solution (phosphoric acid / N, N-dimethylformamide = 0.6 / 100: weight ratio mixed solution) with a polyamic acid concentration of about 2. Diluted to a weight percentage. For the column, HSPgel RT MB-M (manufactured by Waters) was used, and measurement was performed under the conditions of a column temperature of 50 ° C. and a flow rate of 0.40 mL / min using a phosphoric acid-DMF mixed solution as a developing solvent. As the standard polystyrene, TSK standard polystyrene manufactured by Tosoh Corporation was used.

[Evaluation of voltage holding ratio (VHR) reliability]
The voltage holding ratio (VHR) of the liquid crystal display element was determined by applying a rectangular wave with a wave height of ± 5 V to the cell at 60 ° C. according to the method described in “Mizushima et al. Measured. The voltage holding ratio is an index indicating how much the applied voltage is held after the frame period. If this value is 100%, it means that all charges are held. VHR reliability was evaluated by exposing the cell to an LED backlight for 300 hours and measuring VHR again. It means that the higher the VHR after 300 hours, the higher the reliability of the deposited alignment film against light stress. If the VHR after 300 hours is 90% or more, the VHR reliability is good, and if it is 95% or more, it means that the VHR reliability is extremely good.

[Evaluation of transmittance]
A liquid crystal alignment film is formed on a transparent glass substrate, the transmittance of 380 nm to 430 nm is measured with an ultraviolet-visible spectrophotometer V-660 (manufactured by JASCO Corporation), and the average value of the transmittance at 380 nm to 430 nm is calculated. Asked. The larger the value, the more the alignment film is suppressed from being colored, which means that the alignment film has better light transmission characteristics.

[AC afterimage / contrast measurement (evaluation of liquid crystal alignment)]
AC afterimage was measured according to the method described in International Publication No. 2000/43833 pamphlet.
Specifically, the luminance-voltage characteristic (B-V characteristic) of the manufactured liquid crystal cell was measured, and this was defined as the luminance-voltage characteristic before applying stress: B (before). Next, an alternating current of 4.5 V and 60 Hz was applied to the liquid crystal cell for 20 minutes, then shorted for 1 second, and the luminance-voltage characteristics (BV characteristics) were measured again. This is the luminance-voltage characteristic after application of stress: B (after). Then, the luminance change rate ΔB (%) was obtained by the following formula using the measured luminance at a voltage of 1.3 V of each BV characteristic. A smaller value of ΔB (%) means that the occurrence of an AC afterimage can be suppressed, that is, the liquid crystal orientation is better.
ΔB (%) = [B (after) _1.3 −B (before) _1.3 ] / B (before) _1.3 × 100
In the equation, B (before) _1.3 represents the luminance at 1.3 V in the BV characteristic before stress application, and B (after) _1.3 represents the luminance at 1.3 V in the BV characteristic after stress application. .
The luminance change rate ΔB was evaluated according to the following criteria.
ΔB (%) is less than 1.5%: ◎
ΔB (%) is 1.5% or more and less than 2.0%: ○ ΔB (%) is 2.0% or more and less than 3.0%: Δ
ΔB (%) is 3.0% or more: ×

Further, the contrast (CR) was obtained by using the ratio between the minimum luminance and the maximum luminance in the BV characteristics before applying stress. The larger the CR value, the clearer the light and dark display.
CR = B (before) _max / B (before) _min
In the equation, B (before) _max indicates the maximum luminance in the BV characteristic before stress application, and B (before) _min indicates the minimum luminance in the BV characteristic before stress application.
The contrast CR was evaluated according to the following criteria for each liquid crystal composition used.
<When using negative liquid crystal composition A>
CR is over 3500: ◎
CR is 3250 or more and less than 3500: 〇 CR is 3000 or more and less than 3250: △
CR is less than 3000: ×
<When positive type liquid crystal composition B is used>
CR is 3250 or more: ◎
CR is 3000 or more and less than 3250: 〇 CR is 2750 or more and less than 3000: △
CR is less than 2750: ×

Compounds and Solvents Used The diamines used in the preparation of the varnishes in this example are divided into photoreactive diamines having thermal reactivity, photoreactive diamines having no thermal reactivity, and non-photoreactive diamines, and are shown below. . In addition, the diamine represented by Formula (2) was used for the photoreactive diamine which has thermal reactivity.

[Photoreactive diamine with thermal reactivity]

"Photoreactive diamine without thermal reactivity"

[Non-photoreactive diamine]

[Tetracarboxylic dianhydride]
The tetracarboxylic dianhydride used for the preparation of the varnish in this example is shown below.

[Additive]
Additives used in the preparation of the liquid crystal aligning agent in this example are shown below.
AD-1: 2,2 ′-(1,3-phenylene) bis- (2-oxazoline) (abbreviation: 1,3-PBO)
AD-2: Celoxide 8000
AD-3: 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (abbreviation: S530)
AD-4: 3-trimethoxypropyl succinic anhydride AD-5: tris (2-hydroxyethyl) isocyanurate

[solvent]
The solvent used for the preparation of the liquid crystal aligning agent in this example is shown below.
NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether)

Preparation of varnish The varnish used in this example was prepared by the following procedure. Here, the photoreactive diamine used in each of the following preparation examples is a photoreactive diamine having thermal reactivity and a photoreactive diamine having no thermal reactivity in the preparation examples of varnishes 1 to 21, and compared. In the preparation example of varnish 1, it is only photoreactive diamine which has thermal reactivity, and in the preparation example of comparative varnish 2, it is only photoreactive diamine which does not have thermal reactivity. The varnishes 1 to 8 for blending are varnishes into which a photoreactive structure has not been introduced, and are used by blending with other varnishes.

[Varnish Preparation Example 1] Preparation of Varnish 1 In a 100 mL three-necked flask equipped with a stirring blade and a nitrogen introduction tube, 2.2567 g of photoreactive diamine (4-3) having thermal reactivity, thermal reactivity 0.4725 g of non-photoreactive diamine (V-2-1), 0.0852 g of non-photoreactive diamine (DI-4-13), and 0 of non-photoreactive diamine (DI-13-1) 0.0597 g was added, and 64.0 g of N-methyl-2-pyrrolidone was added. To this solution, as tetracarboxylic dianhydride, (AN-4-17, m = 8) 1.8094 g, (AN-2-1) 0.6549 g, and (AN-1-1) 0 6616 g was added and stirred at room temperature for 24 hours. To this reaction liquid, 30.0 g of butyl cellosolve was added, and the mixture was heated and stirred at 70 ° C. until the produced polymer component had the target weight average molecular weight. As a result, a varnish 1 having a polymer component weight average molecular weight of 13,000 and a resin concentration (polymer concentration as a solid content) of 6% by weight was obtained.

[Preparation Examples 2 to 21 of Varnish] Preparation of Varnishes 2 to 21 The same manner as Preparation Example 1 except that the compounds used as diamines and tetracarboxylic dianhydrides and the mixing ratios were changed as shown in Table 1. Varnishes 2 to 21 having a resin concentration of 6% by weight were prepared. At this time, the synthesis conditions of the polymer component were adjusted so that the weight average molecular weight was in the range of 5,000 to 20,000. Table 1 shows the weight average molecular weight of the produced polymer component. In Table 1, in the preparation examples in which two or more compounds are listed as diamines, it means that all the compounds are combined and used as diamines, and two or more compounds are listed as tetracarboxylic dianhydrides. In the prepared preparation examples, it means that all the compounds were combined and used as tetracarboxylic dianhydride. The numerical value in square brackets represents a compounding ratio (mol%), and “-” means that a compound corresponding to that column is not used. The same applies to Tables 2 and 3.

[Comparative Preparation Examples 1 and 2 of Varnish] Preparation of Comparative Varnishes 1 and 2 Same as Preparation Example 1 except that the compounds used as diamines and tetracarboxylic dianhydrides and the blending ratio were changed as shown in Table 2. Comparative varnishes 1 and 2 having a resin concentration of 6% by weight were prepared. Table 2 shows the weight average molecular weight of the produced polymer component.

[Preparation Examples 1 to 8 for Blending Varnish] Preparation of Blending Varnishes 1 to 8 Preparation Example 1 except that the compounds used as diamines and tetracarboxylic dianhydrides and the blending ratio were changed as shown in Table 3. In the same manner, varnishes for blending 1 to 8 having a resin concentration of 6% by weight were prepared. Table 3 shows the weight average molecular weight of the produced polymer components.

Preparation of Liquid Crystal Alignment Agent A liquid crystal alignment agent was prepared by the following procedure using varnishes 1 to 21, varnishes 1 to 8 and comparative varnishes 1 and 2 prepared in each of the above preparation examples.

[Example 1] Preparation of alignment agent 1 Varnish 1 (10.0 g) was weighed and introduced into a 50 mL eggplant flask equipped with a stirring blade and a nitrogen introduction tube, and N-methyl-2-pyrrolidone (1 0.4 g) and butyl cellosolve (0.6 g) were added, and the mixture was stirred at room temperature for 1 hour to obtain an aligning agent 1 having a resin concentration of 5% by weight.

[Examples 2 to 21] Preparation of Alignment Agents 2 to 21 Alignment agents 2 to 21 were prepared in the same manner as in Example 1 except that the varnish shown in Table 4 was used instead of the varnish 1.

[Example 22] Preparation of alignment agent 22 In a 50 mL eggplant flask equipped with a stirring blade and a nitrogen introduction tube, varnish 1 (3.0 g) and varnish 1 for blending (7.0 g) were weighed and put, respectively. N-methyl-2-pyrrolidone (3.5 g) and butyl cellosolve (1.5 g) were added thereto and stirred at room temperature for 1 hour to obtain an aligning agent 22 having a resin concentration of 4% by weight.

[Examples 23 to 59] Preparation of alignment agents 23 to 59 An alignment agent was obtained in the same manner as in Example 22 except that the varnish and the varnish for blending shown in Table 5 were used instead of the varnish 1 and the varnish for blending 1, respectively. 23-59 were prepared.

[Example 60] Preparation of alignment agent 60 Into a 50 mL eggplant flask equipped with a stirring blade and a nitrogen introduction tube, varnish 1 (3.0 g) and varnish 1 for blending (7.0 g) were weighed and put, respectively. Additive (AD-1) was added in an amount of 1% by weight based on the total solid weight, and N-methyl-2-pyrrolidone (3.5 g) and butyl cellosolve (1.5 g) were further added thereto, followed by stirring at room temperature for 1 hour. Thus, an aligning agent 60 having a resin concentration of 4% by weight was obtained.

[Examples 61 to 65] Preparation of alignment agents 61 to 65 Instead of the varnish 1 and the blending varnish 1, the varnish and blending varnish shown in Table 5 were used, respectively, and the additive was completely solid as shown in Table 5. Alignment agents 61 to 65 were prepared in the same manner as in Example 60 except that the addition was made with respect to the partial weight.

[Comparative Examples 1 and 2] Preparation of Comparative Aligning Agents 1 and 2 Comparative Aligning Agents 1 and 2 were prepared in the same manner as in Example 1 except that the comparative varnish shown in Table 6 was used instead of varnish 1.

[Comparative Examples 3 and 4] Preparation of Comparative Alignment Agents 3 and 4 In the same manner as in Example 22 except that the varnish 1 and the blending varnish 1 were used instead of the varnish 1 and the blending varnish 1, respectively. Comparative alignment agents 3 and 4 were prepared.

  Tables 4 to 7 show the varnishes used for preparing the liquid crystal aligning agent in each Example and each Comparative Example.

Evaluation [ Evaluation of voltage holding ratio (VHR) reliability]
By dropping the liquid crystal aligning agents prepared in Examples 1 to 65 and Comparative Examples 1 to 4 onto a glass substrate with an IPS electrode and a glass substrate with a column spacer, and rotating the substrate at 2,000 rpm for 15 seconds by the spinner method. Applied. After coating, the substrate was heated at 60 ° C. for 1 minute to evaporate the solvent, thereby forming a liquid crystal aligning agent film. Multi-light ML-501C / B manufactured by Ushio Electric Co., Ltd. was used for the film of the liquid crystal aligning agent, and ultraviolet linearly polarized light having a wavelength of 365 nm was 2.0 ± 0. Irradiation was performed at 1 J / cm ² to perform photo-alignment treatment. The liquid crystal aligning agent film subjected to the photo-alignment treatment was subjected to a heating and baking process at 220 ° C. for 30 minutes to form a liquid crystal alignment film having a thickness of 100 nm. Next, two substrates on which the liquid crystal alignment film is formed are opposed to each other on the surface on which the liquid crystal alignment film is formed, and a gap for injecting the liquid crystal composition is formed between the opposing liquid crystal alignment films. Were pasted together. At this time, the direction of the substrate was set so that the polarization directions of the linearly polarized light irradiated to each liquid crystal alignment film in the photo-alignment process were parallel to each other. A negative liquid crystal composition A having the following composition was injected into the gap between the bonded substrates to prepare a liquid crystal cell (liquid crystal display element) having a cell thickness of 7 μm.

<Negative liquid crystal composition A>

(Physical property value)
Phase transition temperature NI: 75.7 ° C., dielectric anisotropy Δε: −4.1, refractive index anisotropy Δn: 0.101, viscosity η: 14.5 mPa · s.

About each produced liquid crystal cell, the voltage retention (initial voltage retention) was measured at 5V and 30Hz. Subsequently, a liquid crystal cell was placed on the illuminated backlight tester (Fuji Film LED Viewer Pro HR-2; luminance 2,700 cd / m ² ) manufactured by Fuji Film Co., Ltd., and held for 300 hours. The subsequent voltage holding ratio was measured. The results are shown in Tables 8-10.

  As shown in Table 8, an aligning agent obtained by mixing varnishes 1 to 21 with varnishes 1 to 21 prepared using both a photoreactive diamine having thermal reactivity and a photoreactive diamine having no thermal reactivity. The liquid crystal cell using 22 to 65 showed a voltage holding ratio of 90% or more after 300 hours of backlight irradiation, and good VHR reliability could be obtained. On the other hand, as shown in Tables 9 and 10, the liquid crystal cell by the comparative alignment agent 2 of the comparative varnish 2 prepared using only the photoreactive diamine having no thermal reactivity as the photoreactive diamine, and the comparison In the liquid crystal cell using the comparative alignment agent 4 in which the varnish 2 was mixed with the varnish 2, the voltage holding ratio after backlight irradiation was less than 90%. This is presumably because the electrical properties of the liquid crystal alignment film deteriorated with the photochemical reaction of the azobenzene structure caused by backlight irradiation. In addition, in the alignment agents 22 to 65, although the photoreactive diamine having no thermal reactivity is used in combination with the preparation of the varnish, good VHR reliability is obtained because of the thermal reactivity. It is presumed that the structure formed by the intramolecular chemical reaction of the photoreactive diamine possessed is very stable to light.

[Evaluation of transmittance]
Using the liquid crystal aligning agents prepared in Examples 1 to 65 and Comparative Examples 1 to 4, a coating film of the liquid crystal aligning agent was formed on the transparent glass substrate under the same conditions as the evaluation of the voltage holding ratio. Subsequently, a liquid crystal alignment film having a film thickness of 100 nm is formed by heating and baking the substrate at 220 ° C. for 30 minutes, and an ultraviolet-visible transmittance spectrum of the substrate is measured, and the transmittance in the range of 380 nm to 430 nm is measured. The average value was obtained. The results are shown in Tables 11-14.

As shown in Table 13, the liquid crystal alignment film by the comparative alignment agent 2 of the comparative varnish 2 prepared using only the photoreactive diamine having no thermal reactivity as the photoreactive diamine had a transmittance of 71%. . On the other hand, as shown in Table 11, alignment agents 1 to 21 including varnishes 1 to 21 prepared using both a photoreactive diamine having thermal reactivity and a photoreactive diamine having no thermal reactivity. Each of the liquid crystal alignment films showed higher transmittance than the liquid crystal alignment film of the comparative alignment agent 2.
Further, as shown in Tables 12 and 14, the same tendency was observed in the system using the varnish for blending. That is, the liquid crystal alignment film of the comparative alignment agent 4 obtained by mixing the varnish 1 for blending with the comparative varnish 2 prepared using only the photoreactive diamine having no thermal reactivity as the photoreactive diamine has a transmittance of 79%. there were. On the other hand, the alignment agent 22 ~ which mixed the varnish 1-8 for blending with the varnish 1-21 prepared using both the photoreactive diamine which has thermal reactivity, and the photoreactive diamine which does not have thermal reactivity. All of the liquid crystal alignment films of 65 showed higher transmittance than the liquid crystal alignment film of the comparative alignment agent 4.
The high transmittance in the system using the photoreactive diamine having thermal reactivity is due to the fact that the azobenzene structure derived from the photoreactive diamine having thermal reactivity forms an indazole ring by heating and baking of the film. This is considered to be due to a decrease in absorbance in the absorption band (380 nm to 430 nm) derived from the structure. From this, it was confirmed that the thermal reactivity introduced into the liquid crystal alignment film using the photoreactive diamine having thermal reactivity surely functions as a structure that chemically changes by heating and baking of the film.

[Evaluation of AC afterimage characteristics and contrast characteristics (evaluation of liquid crystal alignment)]
Using the liquid crystal aligning agents prepared in Examples 1 to 65 and Comparative Examples 1 to 4, a glass substrate with FFS electrodes and a glass substrate with column spacers, and a liquid crystal alignment film having a film thickness of 100 nm under the same conditions as the evaluation of voltage holding ratio Formed. The two substrates on which these liquid crystal alignment films are formed are opposed to each other on the surface on which the liquid crystal alignment film is formed, and a gap for injecting the liquid crystal composition is formed between the opposing liquid crystal alignment films. Were pasted together. At this time, the direction of the substrate was set so that the polarization directions of the linearly polarized light irradiated to each liquid crystal alignment film in the photo-alignment process were parallel to each other. A negative liquid crystal composition A having the above composition or a positive liquid crystal composition B described below is injected into the gap between the bonded substrates, the injection port is sealed with a photocuring agent, and a liquid crystal cell having a cell thickness of 4 μm ( A liquid crystal display element) was produced. With respect to the obtained liquid crystal cell, the luminance change rate ΔB at 1.3 V before and after the stress application and the ratio CR of the maximum luminance and the minimum luminance in the BV characteristic are measured, and the AC residual characteristic and the contrast characteristic are measured. evaluated. The results are shown in Tables 15-18.

<Positive liquid crystal composition B>
(Physical property value)
Phase transition temperature NI: 100.1 ° C., dielectric anisotropy Δε: 5.1, refractive index anisotropy Δn: 0.093, viscosity η: 25.6 mPa · s.

As shown in Tables 15 and 16, alignment agents 1-21, including varnishes 1-21, prepared using both photoreactive diamine having thermal reactivity and photoreactive diamine not having thermal reactivity, varnish 1 Each of the liquid crystal cells using the alignment agents 22 to 65 in which the blending varnishes 1 to 8 are mixed with the varnish 21 to 21 has a luminance change rate ΔB of less than 3.0% (Δ to ◎) due to the application of stress. AC residual characteristics were exhibited. In addition, each liquid crystal cell using the alignment agents 1 to 65 had a ratio CR between the maximum luminance and the minimum luminance of 3000 or more (Δ to ◎), and was able to display light and dark with high contrast. In particular, each liquid crystal cell using the alignment agents 1, 2, 8, 22, 23, 33, 35, and 36 has an evaluation of ΔB of ◎ when either of the two liquid crystal compositions A and B is used. Thus, the CR was evaluated as “◎”, showed excellent AC residual characteristics, and bright and dark display could be performed with a very high contrast.
On the other hand, the comparative alignment agent 1 by the comparative varnish 1 prepared using only the photoreactive diamine having thermal reactivity as the photoreactive diamine, or the comparative alignment agent obtained by mixing the varnish 1 for blending with the comparative varnish 1 Each of the liquid crystal cells using 3 had a lower CR than the liquid crystal cell using the alignment agents 1 to 65, and the bright and dark display was unclear. On the other hand, the comparative alignment agent 2 by the comparative varnish 2 prepared using only the photoreactive diamine having no thermal reactivity as the photoreactive diamine, or the comparative alignment agent 4 in which the comparative varnish 2 and the blending varnish 1 are mixed. Each liquid crystal cell used had a larger ΔB and inferior AC residual characteristics than the liquid crystal cell using the alignment agents 1 to 65.
From the above results, the transmittance of the liquid crystal alignment film can be obtained by using, as a liquid crystal aligning agent, a varnish prepared by combining a photoreactive diamine having thermal reactivity with a photoreactive diamine not having thermal reactivity. It has been found that both AC afterimage characteristics and contrast characteristics can be remarkably improved in a liquid crystal cell to which the liquid crystal alignment film is applied without substantially impairing VHR reliability.

[Evaluation of Liquid Crystal Alignment Film Formed by Two-Step Firing]
A liquid crystal was produced in the same manner as described above, except that the alignment agents 3 and 24 prepared in Examples 3 and 24 were used and the coating film of each alignment agent was heated and baked in two stages, a low temperature baking step and a high temperature baking step. An alignment film is formed, and the average transmittance at 380 to 430 nm, the voltage holding ratio of the liquid crystal cell to which the liquid crystal alignment film is applied, the luminance change rate ΔB by applying stress, and the ratio CR between the maximum luminance and the minimum luminance are measured. did.
Here, in the low temperature baking process, the coating film was baked at a low temperature of 110 ° C. to 170 ° C., and in the high temperature baking process, the coating film was baked at a high temperature of 210 ° C. to 230 ° C. Table 19 shows the specific conditions for each firing step and the measurement results for each characteristic.

  As shown in Table 19, in the system using the aligning agent 3, the high-temperature baking is performed at 220 ° C./30 steps by performing the low-temperature baking step in the range of 140 to 170 ° C. before the high-temperature baking step. Compared with the case where it performed, (DELTA) B (AC residual characteristic) was improved and contrast CR improved. Moreover, in the system using the aligning agent 24, by performing the low-temperature baking process in the range of 130 to 170 ° C. before the high-temperature baking process, compared with the case where high-temperature baking is performed at one stage of 220 ° C./30. As a result, ΔB (AC residual characteristic) was improved and the contrast CR was improved. From this, it was found that the AC afterimage characteristics and contrast characteristics of the liquid crystal cell to which the liquid crystal alignment film was applied can be further improved by performing baking of the liquid crystal alignment agent film in two stages and appropriately adjusting the baking temperature. . In one-step high-temperature firing, various reactions induced by heat, including imidization and indazole ring formation, occur almost simultaneously, whereas in two-step firing, a low-temperature firing step and a high-temperature firing step. It is considered that the polymer chains are more uniformly oriented by the occurrence of these reactions stepwise.

  If the liquid crystal aligning agent for photo-alignment of the present invention is used, a high voltage holding ratio and light resistance can be maintained even when used for a long time, and a liquid crystal display element with high display quality can be provided. The liquid crystal aligning agent for photo-alignment of the present invention can be suitably applied to a lateral electric field type liquid crystal display element. Further, the liquid crystal alignment film of the present invention can also be used for a microwave / millimeter wave wide band variable phase shifter using liquid crystal. This broadband variable phase shifter can be suitably used for an antenna for controlling the phase of an electromagnetic wave signal.

Claims (27)

A liquid crystal aligning agent for photo-alignment containing a polymer component having a structural unit containing a photoreactive structure,
The polymer component comprises a polymer obtained by polymerizing a monomer composition containing at least a first monomer and a second monomer, or a derivative thereof,
The first monomer includes a photoreactive structure in a portion that forms the structural unit of the polymer, and includes a structure in which a portion that forms the structural unit of the polymer causes a chemical reaction by heating,
The second monomer includes a photoreactive structure in a portion that forms a constituent unit of the polymer, and a portion that forms a constituent unit of the polymer does not cause a chemical reaction due to heating. Liquid crystal aligning agent for alignment.   The liquid crystal aligning agent for photo-alignment according to claim 1, wherein the chemical reaction in the first monomer is a cyclization reaction. The first monomer includes a photoreactive structure having at least one of a structure represented by the following formula (a-1) and a structure represented by the following formula (a-2). The liquid crystal aligning agent for optical alignment of description.
[In the formula (a-1), R ^a represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group. Represents;
In formula (a-2), R ^b and R ^c are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted group Or an unsubstituted arylcarbonyl group;
In formula (a-1) and formula (a-2), * represents a bonding position with a photoreactive group. ]   The liquid crystal aligning agent for photo-alignment of any one of Claims 1-3 in which the said 1st monomer contains the photoreactive structure which has a photoisomerization structure or a light Fleece rearrangement structure. The liquid crystal aligning agent for photo-alignment of any one of Claims 1-4 in which a said 1st monomer contains the photoreactive structure which has a structure represented by following formula (1).
[In Formula (1), R ¹ and R ² each independently represent a hydrogen atom, a group represented by the following Formula (1-1) or the following Formula (1-2), and R ¹ and R ² Is at least one group represented by the following formula (1-1) or the following formula (1-2);
* Represents a bonding position on the benzene ring, and is either one of the positions that can be replaced with a hydrogen atom on one benzene ring or the position that can be replaced with a hydrogen atom on the other benzene ring;
The hydrogen atom of the benzene ring may be substituted with a substituent. ]
[In Formula (1-1) and Formula (1-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, substituted or unsubstituted Represents a substituted alkoxycarbonyl group or a substituted or unsubstituted arylcarbonyl group;
* Represents the bonding position to the benzene ring in formula (1). ] The polymer obtained by polymerizing the monomer composition or a derivative thereof is at least one selected from polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer and polyamideimide,
The liquid crystal aligning agent for photo-alignment of any one of Claims 1-5 whose said 1st monomer is diamine represented by following formula (2).
[In Formula (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by Formula (1-1) or Formula (1-2), and at least ^one of R ¹ and R ² One is a group represented by formula (1-1) or formula (1-2);
R ⁶ and R ⁸ are each independently a linear alkylene group having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, —CON (CH ₃ ) — or a single bond, and in R ⁶ and R ⁸ , one of —CH ₂ — in the linear alkylene group or two that are not adjacent to each other may be replaced by —O—;
R ⁷ and R ⁹ each independently represents a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, a heterocyclic ring, or a single bond;
The bonding position of H ₂ N—R ⁷ —R ⁶ — is one of the positions capable of substituting for a hydrogen atom in one benzene ring, and the bonding position of H ₂ N—R ⁹ —R ⁸ — is the other bonding position. Any of the possible substitution positions for a hydrogen atom in the benzene ring;
The hydrogen atom in the benzene ring may be substituted with a substituent. ]
[In Formula (1-1) and Formula (1-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, substituted or unsubstituted Represents a substituted alkoxycarbonyl group or a substituted or unsubstituted arylcarbonyl group;
* Represents the bonding position to the benzene ring in formula (2). ] The liquid crystal aligning agent for photo-alignment of Claim 5 or 6 whose R < ¹ > is group represented by Formula (1-1) and whose R < ² > is a hydrogen atom. The liquid crystal aligning agent for photo-alignment according to claim 7, wherein R ⁴ is a hydrogen atom or a substituted or unsubstituted alkyl group. The diamine represented by said Formula (2) is the liquid crystal aligning agent for photo-alignment of Claim 6 which is a diamine represented by either of following formula (3)-(6).
[In the formulas (3) to (6), R ⁴ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or substituted or unsubstituted Represents an unsubstituted arylcarbonyl group;
The hydrogen atom of the benzene ring may be substituted with a substituent;
In Formula (5) and Formula (6), R ⁵ is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, a substituted or unsubstituted alkoxycarbonyl group, or substituted or unsubstituted Represents an unsubstituted arylcarbonyl group. ] The diamine represented by the formula (2) is represented by the following formula (3-1) to formula (3-9), formula (4-1) to formula (4-9), formula (5-1), formula ( The liquid crystal aligning agent for photo-alignment of Claim 6 or 9 which is diamine represented by either 5-2), Formula (6-1), and Formula (6-2).
[In the formula, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, ⁱ Pr represents an isopropyl group, Bu represents a butyl group, and ^t Bu represents a t-butyl group. ]   The liquid crystal aligning agent for photo-alignment of any one of Claims 1-10 in which the said 2nd monomer contains the photoreactive structure which has a photoisomerization structure or a photodimerization structure.   The liquid crystal aligning agent for photo-alignment according to claim 11, wherein the second monomer includes a photoreactive structure having a photoisomerization structure.   The liquid crystal aligning agent for photo-alignment of any one of Claims 6-12 whose said 2nd monomer is diamine.   The liquid crystal aligning agent for photo-alignment of any one of Claims 6-13 in which the said monomer composition contains tetracarboxylic dianhydride.   The blending amount of the first monomer in the monomer composition is 15 to 85 mol% with respect to the total number of moles of the first monomer and the second monomer. Item 4. A liquid crystal aligning agent for photo-alignment according to item. The liquid crystal aligning agent further contains a second polymer component,
The said 2nd polymer component consists of a polymer or its derivative which polymerizes the monomer composition which consists of a monomer which does not contain a photoreactive structure, For photo-alignment of any one of Claims 1-15 Liquid crystal aligning agent.   The polymer obtained by polymerizing the monomer composition or a derivative thereof is at least one selected from polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide. The liquid crystal aligning agent for optical alignment of description.   The liquid crystal aligning agent for photo-alignment of any one of Claims 1-17 used for formation of the liquid crystal aligning film of a horizontal electric field type liquid crystal display element.   The liquid crystal aligning film formed with the liquid crystal aligning agent for photo-alignment of any one of Claims 1-18.   The liquid crystal display element which has a liquid crystal aligning film of Claim 19. An alignment process for imparting anisotropy by irradiating polarized light to a film comprising the liquid crystal aligning agent for photo-alignment according to any one of claims 1 to 18, and heating the anisotropy film Having a heating and baking step of baking,
A method for forming a liquid crystal alignment film, wherein a cyclization reaction is caused in a photoreactive structure of a polymer component included in the liquid crystal aligning agent for photoalignment to reduce a photoreactive group during the heating and baking step.   The method for forming a liquid crystal alignment film according to claim 21, wherein the heating and baking step is performed in two or more steps by changing a heating temperature.   A method for manufacturing a liquid crystal display element, wherein the liquid crystal alignment film is formed using the method for forming a liquid crystal alignment film according to claim 21 or claim 22.   The method for manufacturing a liquid crystal display element according to claim 23, wherein the liquid crystal display element to be manufactured is a horizontal electric field type liquid crystal display element. A polyamic acid or a derivative thereof obtained by polymerizing a monomer composition containing a first monomer, a second monomer, and a non-photoreactive tetracarboxylic dianhydride,
The first monomer is a diamine represented by the following formula (2):
The second monomer is represented by the following formula (II-1), formula (II-2), formula (III-1), formula (III-2), formula (IV-1), formula (IV-2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula The polyamic acid or a derivative thereof, which is a compound represented by any one of (VIII-1) and formula (VIII-2).
[In Formula (2), R ¹ and R ² each independently represent a hydrogen atom, a group represented by Formula (1-1) or Formula (1-2), and at least ^one of R ¹ and R ² One is a group represented by formula (1-1) or formula (1-2);
R ⁶ and R ⁸ are each independently a linear alkylene group having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, —CON (CH ₃ ) — or a single bond, and in R ⁶ and R ⁸ , one of —CH ₂ — in the linear alkylene group or two that are not adjacent to each other may be replaced by —O—;
R ⁷ and R ⁹ each independently represents a monocyclic hydrocarbon, a condensed polycyclic hydrocarbon, a heterocyclic ring, or a single bond;
The bonding position of H ₂ N—R ⁷ —R ⁶ — is one of the positions capable of substituting for a hydrogen atom in one benzene ring, and the bonding position of H ₂ N—R ⁹ —R ⁸ — is the other bonding position. Any of the possible substitution positions for a hydrogen atom in the benzene ring;
The hydrogen atom in the benzene ring may be substituted with a substituent. ]
[In Formula (1-1) and Formula (1-2), R ⁴ and R ⁵ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, substituted or unsubstituted Represents a substituted alkoxycarbonyl group or a substituted or unsubstituted arylcarbonyl group;
* Represents the bonding position to the benzene ring in formula (2). ]
(Formula (II-1), Formula (II-2), Formula (III-1), Formula (III-2), Formula (IV-1), Formula (IV-2), Formula (IV-3), Formula (V-1), Formula (V-2), Formula (V-3), Formula (VI-1), Formula (VI-2), Formula (VII-1), Formula (VIII-1), and In the formula (VIII-2), a group whose bonding position is not fixed to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary, and in the formula (IV-3), r Is an integer of 1 to 10, and in formula (V-2), R ⁶ independently represents —CH ₃ , —OCH ₃ , —CF ₃ , or —COOCH ₃ , and a independently represents 0 to 2 In formula (V-3), ring A and ring B are each independently selected from monocyclic hydrocarbons, condensed polycyclic hydrocarbons and heterocyclic rings. R ¹¹ represents at least one, and R ¹¹ represents a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, or —CON (CH ₃ )-and R ¹² represents a linear alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO—, —CONH—, —N (CH ₃ ) CO—, or —CON (CH ₃ )-, in R ¹¹ and R ¹² , one or two of the linear alkylene —CH ₂ — may be substituted with —O—, and R ^{7 to} R ¹⁰ are each independently -F, -CH _3, -OCH _3, represents -CF ₃ or -OH,, b to e are each independently an integer of 0 to 4, in formula (VII-1), R ⁴ and R ⁶ is independently straight-chain alkylene having 1 to 20 carbon atoms, —COO—, —OCO—, —NHCO. —, —CONH—, —N (CH ₃ ) CO—, —CON (CH ₃ ) —, or a single bond, in R ⁴ and R ⁶ , one or not of —CH ₂ — of the linear alkylene may be two replaced by -O-, R ⁵ and R ⁷ independently represent monocyclic hydrocarbon, fused polycyclic hydrocarbon, a heterocycle, or a single bond.) The second monomer is represented by the following formula (V-2-1), formula (V-3-2), formula (VI-2-1), formula (VII-1-1) and formula (VII-1-2). The polyamic acid according to claim 25 or a derivative thereof.
27. The polyamic acid or derivative thereof according to claim 25 or 26, comprising at least one selected from polyamic acid, polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer and polyamideimide.