Liquid crystal light control element

Abstract

The present invention provides a liquid crystal light control element which uses a liquid crystal composition that contains liquid crystals and a chiral compound, in which display defects due to alignment defects of the liquid crystals do not occur even if the liquid crystal light control element is subjected to light irradiation for a long period of time.　Provided is a liquid crystal light control element which has a transmittance that is variable in response to voltage application, and which is characterized by comprising: a pair of substrates that are provided with electrodes; a liquid crystal layer that is provided between the substrates and comprises liquid crystal molecules which are twist-aligned when a voltage is not applied thereto; and a liquid crystal alignment film that has a function of generally horizontally aligning liquid crystal molecules in at least one of the spaces between the substrates and the liquid crystal layer. This liquid crystal light control element is also characterized in that the liquid crystal alignment film contains a polymer which includes at least one kind of structure selected from formula [1] and formula [2], and when the thickness of the liquid crystal layer is defined by d and the chiral pitch of the liquid crystals of the liquid crystal layer is defined by p, d / p is 1-10. (In the formulae, the meaning of each symbol is as defined in the description.)

Description

Liquid crystal dimming element

[0001] The present invention relates to a liquid crystal light control element, a liquid crystal alignment film used therein, and a liquid crystal aligning agent for forming the liquid crystal alignment film.

[0002] As an alternative to conventional curtains and blinds, many electric light control devices have been proposed that variably control the amount of light transmission and visibility depending on the level of externally applied voltage, and liquid crystal light control devices are one such device. Various liquid crystal light control device types are known, including a guest-host liquid crystal type that uses liquid crystal and a dichroic dye. This type requires an increased amount of dichroic dye to increase the difference in transmittance between the transmissive state and the non-transmissive state (hereinafter also referred to as the "transmittance difference"). However, dichroic dyes generally have low solubility in liquid crystals, making it difficult to increase the amount. On the other hand, in the guest-host liquid crystal type, the transmittance difference can be increased by adding a chiral compound to the liquid crystal (see Patent Documents 1 to 3).

[0003] Japanese Unexamined Patent Publication No. 6-67173 Japanese Unexamined Patent Publication No. 2018-106080 Japanese Special Publication No. 2023-530439

[0004] In systems using a liquid crystal composition containing liquid crystal and a chiral compound, a large amount of chiral compound must be added to the liquid crystal to increase the transmittance difference. However, this large amount of chiral compound can cause poor alignment of the liquid crystal, making the liquid crystal light control device more susceptible to display defects. Furthermore, because liquid crystal light control devices are sometimes attached to the window glass of automobiles or buildings, they must be able to withstand harsh environments where they are exposed to light for long periods of time, preventing display defects. Therefore, an object of the present invention is to provide a liquid crystal light control device that uses a liquid crystal composition containing liquid crystal and a chiral compound and does not suffer from display defects associated with poor alignment of the liquid crystal. Another object of the present invention is to provide a liquid crystal light control device that does not suffer from such defects even in environments where it is exposed to light for long periods of time.

[0005] The present inventors have conducted extensive research to achieve the above object, and have completed the present invention, which has the following gist: A liquid crystal light control element whose transmittance is variable in response to the application of a voltage, comprising: a pair of substrates each having an electrode; a liquid crystal layer provided between the substrates and containing liquid crystal molecules that are twist-aligned when no voltage is applied; and a liquid crystal alignment film at least one of the substrates and the liquid crystal layer, the liquid crystal layer having a function of aligning the liquid crystal molecules approximately horizontally, wherein the liquid crystal layer contains a liquid crystal composition containing a liquid crystal having positive dielectric anisotropy and a chiral compound, and the liquid crystal alignment film contains a polymer (hereinafter also referred to as a "specific polymer") containing at least one structure selected from the following formulas [1] and [2] (hereinafter also referred to as "specific structure (1)" and "specific structure (2)"), and wherein d / p is 1 to 10, where d is the thickness of the liquid crystal layer and p is the chiral pitch of the liquid crystal in the liquid crystal layer.

[0006] (X １ and X ２ R each represents a single bond or a divalent organic group containing a benzene ring. １ ~R ４ Each represents an alkyl group having 1 to 20 carbon atoms, a halogen atom, or a trifluoromethyl group. Each of r1 to r4 represents an integer of 0 to 2. * represents a bond.

[0007] (Y １ and Y ２ R each represents a single bond or a divalent organic group containing a benzene ring. ５ ~R ８ represents an alkyl group having 1 to 20 carbon atoms, fluorine, or trifluoromethyl group. r5 to r8 each represent an integer of 0 to 2. * represents a bond.

[0008] According to the present invention, a liquid crystal light control device using a liquid crystal composition containing a liquid crystal and a chiral compound does not suffer from display defects due to poor alignment of the liquid crystal, and furthermore, a liquid crystal light control device is obtained that does not suffer from these defects even in an environment where it is exposed to light irradiation for a long period of time. Therefore, the liquid crystal light control device of the present invention is useful for light control windows and optical shutters that control the transmission and blocking of light.

[0009] The mechanism by which the present invention provides a liquid crystal light control element with the above-described excellent properties is not entirely clear, but is generally presumed to be as follows. The liquid crystal used in the present invention has a significantly higher viscosity than the liquid crystals used in general liquid crystal display elements with a d / p ratio of less than 1, resulting in a greater physical load on the liquid crystal alignment film during operation. Therefore, when a liquid crystal alignment film containing a polymer with side chains is used, the side chains are subjected to a physical load when the highly viscous liquid crystal is driven, causing the side chains to orient in a direction different from their initial orientation. This reduces the liquid crystal alignment ability of the liquid crystal alignment film, making it more likely to suffer from poor liquid crystal alignment during operation. Furthermore, when a liquid crystal alignment film containing a polymer without side chains is used, the liquid crystal is highly viscous, so unless the liquid crystal alignment ability of the liquid crystal alignment film is high, the liquid crystal cannot be quickly aligned, making it more likely to suffer from poor alignment. In contrast, in liquid crystal alignment films containing specific polymers, the fluorene ring moieties in specific structures (1) and (2) are directly connected to the main chain of the specific polymer via a quaternary carbon, and are therefore more rigidly fixed than typical side chains. Therefore, the fluorene ring moiety can exist without succumbing to a large physical load even when it is applied, and therefore can strongly align the liquid crystal even when a highly viscous liquid crystal is driven.

[0010] Furthermore, since the fluorene ring has a benzene ring and a cyclo ring, it has a strong interaction with the liquid crystal. Therefore, when a liquid crystal alignment film containing a specific polymer is subjected to an alignment treatment such as rubbing treatment or photoalignment treatment, the liquid crystal interacts with the fluorene ring in addition to the imide group in the specific polymer, and the liquid crystal can be strongly aligned. Furthermore, the fluorene ring itself has a rigid structure, and the interaction between the fluorene rings allows the liquid crystal to exist stably against heat and light. Therefore, the liquid crystal that is strongly aligned immediately after fabrication of the liquid crystal dimming element can maintain its alignment state even when exposed to heat or light irradiation.

[0011] The present invention will be described in detail below. <Specific Structure (1)> Specific structure (1) is a structure of the above formula [1]. In formula [1], X １ , X ２ , R １~R ４ and r1 to r4 are as defined above, but among them, the following are preferred: X １ is a single bond, -O-Ph-*1, -CO-Ph-*1, -N(A)-Ph-*1, -COO-Ph-*1, -OCO-Ph-*1, -CON(A)-Ph-*1, -N(A)CO-Ph-*1, -(CH ２ ) ａＸ -Ph-*1 (aX represents an integer of 1 to 6), -(CH ２ ) ｂＸ -O-Ph-*1 (bX represents an integer of 1 to 6) or -O-(CH ２ ) ｃＸ -Ph-*1 (cX represents an integer of 1 to 6) is preferred, where Ph represents a benzene ring, A represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group, or a 9-fluorenylmethyloxycarbonyl group, and *1 represents a bond to the carbon atom at position 9 of the fluorene skeleton. A single bond, -O-Ph-*1, -COO-Ph-*1, -OCO-Ph-*1, -CON(A)-Ph-*1, or -N(A)CO-Ph-*1 is more preferred. A single bond or -O-Ph-*1 is particularly preferred. X ２ is a single bond, *2-Ph-O-, *2-Ph-CO-, *2-Ph-N(A)-, *2-Ph-COO-, *2-Ph-OCO-, *2-Ph-CON(A)-, *2-Ph-N(A)CO-, *2-Ph-(CH ２ ) ｄＸ - (dX represents an integer of 1 to 6), *2-Ph-(CH ２ ) ｅＸ -O- (eX represents an integer of 1 to 6) or *2-Ph-O-(CH ２ ) ｆＸ- (fX represents an integer of 1 to 6) is preferred, Ph represents a benzene ring, A represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group or a 9-fluorenylmethyloxycarbonyl group, and *2 represents a bond to the carbon atom at position 9 of the fluorene skeleton. More preferred are a single bond, *2-Ph-O-, *2-Ph-COO-, *2-Ph-OCO-, *2-Ph-CON(A)- or *2-Ph-N(A)CO-. Particularly preferred is a single bond or *2-Ph-O-. R １ ~R ４ is preferably a methyl group or an ethyl group. Each of r1 to r4 is preferably an integer of 0 or 1. 0 is particularly preferred.

[0012] <Specific Structure (2)> Specific structure (2) is a structure of the above formula [2]. In formula [2], Y １ , Y ２ , R ５ ~R ８ and r5 to r8 are as defined above, but among them, the following are preferred: １ is a single bond, -O-Ph-*3, -CO-Ph-*3, -N(B)-Ph-*3, -COO-Ph-*3, -OCO-Ph-*3, -CON(B)-Ph-*3, -N(B)CO-Ph-*3, -(CH ２ ) ａＹ -Ph-*3 (aY represents an integer of 1 to 6), -(CH ２ ) ｂＹ -O-Ph-*3 (wherein bY represents an integer of 1 to 6) or -O-(CH ２ ) ｃＹ -Ph-*3 (cY represents an integer of 1 to 6) is preferred, where Ph represents a benzene ring, B represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group, or a 9-fluorenylmethyloxycarbonyl group, and *3 represents a bond to the carbon atom at position 9 of the fluorene skeleton. A single bond, -O-Ph-*3, -COO-Ph-*3, -OCO-Ph-*3, -CON(B)-Ph-*3, or -N(B)CO-Ph-*3 is more preferred. A single bond or -O-Ph-*3 is particularly preferred. Y ２is a single bond, *4-Ph-O-, *4-Ph-CO-, *4-Ph-N(B)-, *4-Ph-COO-, *4-Ph-OCO-, *4-Ph-CON(B)-, *4-Ph-N(B)CO-, *4-Ph-(CH ２ ) ｄＹ - (dY represents an integer of 1 to 6), *4-Ph-(CH ２ ) ｅＹ -O- (eY represents an integer of 1 to 6) or *4-Ph-O-(CH ２ ) ｆＹ - (fY represents an integer of 1 to 6) is preferred, Ph represents a benzene ring, B represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group or a 9-fluorenylmethyloxycarbonyl group, and *4 represents a bond to the carbon atom at position 9 of the fluorene skeleton. More preferred are a single bond, *4-Ph-O-, *4-Ph-COO-, *4-Ph-OCO-, *4-Ph-CON(B)- or *4-Ph-N(B)CO-. Particularly preferred is a single bond or *4-Ph-O-. R ５ ~R ８ is preferably a methyl group or an ethyl group. Each of r5 to r8 is preferably an integer of 0 or 1. 0 is particularly preferred.

[0013] <Specific Polymer> The specific polymer is a polymer containing at least one structure selected from specific structure (1) and specific structure (2). The specific polymer is not particularly limited, but is preferably a polyimide precursor or polyimide (hereinafter also collectively referred to as "polyimide-based polymer"), which is preferably obtained by reacting a diamine component with a tetracarboxylic acid component.

[0014] The polyimide precursor is preferably a polyamic acid or a polyamic acid ester having a structure of the following formula [A].

[0015] (R ａ represents a tetravalent organic group. ｂ represents a divalent organic group. １ and A ２ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and may be the same or different. ３and A ４ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an acetyl group, and may be the same or different. n represents a positive integer.

[0016] The polyimide has a structure of the following formula [A-4] and can be obtained by ring-closing (hereinafter also referred to as "imidization") a polyamic acid of a polyimide precursor. In this case, if the ring-closure rate of the amic acid group (hereinafter also referred to as "imidization rate") is less than 100%, the polyimide contains at least one of the structures of the following formulas [A-1] to [A-3] in addition to the structure of formula [A-4].

[0017] (R ａ , R ｂ and A １ ~A ４ has the same meaning as defined in the above formula [A].

[0018] The diamine component is a diamine having two primary or secondary amino groups in the molecule, and the tetracarboxylic acid component includes a tetracarboxylic acid compound, a tetracarboxylic acid dianhydride, a tetracarboxylic acid dihalide compound, a tetracarboxylic acid dialkyl ester compound, and a tetracarboxylic acid dialkyl ester dihalide compound.

[0019] The polyimide polymer is preferably a polyamic acid having a repeating unit structure of the following formula [D] or a polyimide obtained by imidizing the polyamic acid, because the polyimide polymer can be obtained relatively easily by using a tetracarboxylic dianhydride of the following formula [B] and a diamine of the following formula [C] as raw materials.

[0020] (R ａ and R ｂ has the same meaning as defined in the above formula [A].

[0021] (R ａ and R ｂ has the same meaning as defined in the above formula [A]. n represents a positive integer.

[0022] In addition, a polymer having a repeating unit structure of the above formula [D] may be synthesized by a conventional synthesis method. １ and A ２and A in formula [A] ３ and A ４ It is also possible to introduce an alkyl group having 1 to 5 carbon atoms or an acetyl group.

[0023] In the method for introducing the specific structure (1) into a polyimide polymer, it is preferable to use a diamine having the specific structure (1) as part of the raw material. In particular, it is preferable to use a diamine of the following formula [1-1a] (hereinafter also referred to as a "specific diamine"):

[0024]

[0025] X in formula [1-1a] １ , X ２ , R １ ~R ４ Details of r1 to r4 and preferred combinations are as described above. １ and A ２ Each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Of these, a hydrogen atom or a methyl group is preferred.

[0026] More specifically, the specific diamine of the following formula [1-2a] can be mentioned.

[0027] X ３ and X ６ Each of X represents a benzene ring. ４ and X ５ respectively represent a single bond, -O-, -CO-, -N(A)-, -COO-, -OCO-, -CON(A)- or -N(A)CO-, and A represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group or a 9-fluorenylmethyloxycarbonyl group. Among these, a single bond, -O-, -COO-, -OCO-, -CO-N(A)- or -N(A)CO- is preferred. A single bond or -O- is more preferred. X ａ and X ｂ are each a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or X ａ and X ｂand *-X-* (X is a single bond or an oxygen atom. * is a bond to the benzene ring) in which X and X are combined together. Among these, hydrogen atoms, halogen atoms other than fluorine atoms, methyl groups, or X ａ and X ｂ and m2 are preferably combined with each other to form *-X-*. m1 and m2 each represent an integer of 0 to 2. Of these, 0 or 1 is preferred. R １ ~R ４ Each of r1 to r4 represents an alkyl group having 1 to 20 carbon atoms, a halogen atom, or a trifluoromethyl group. Of these, a methyl group or an ethyl group is preferred. Each of r1 to r4 represents an integer of 0 to 2. Of these, 0 or 1 is preferred. 0 is particularly preferred. A １ and A ２ Each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Of these, a hydrogen atom or a methyl group is preferred.

[0028] Specific examples of the specific diamine include the following formulas [1a-1] to [1a-8].

[0029]

[0030] Among these, from the viewpoint of suitably obtaining the effects of the present invention, formula [1a-1], formula [1a-2], and formula [1a-4] to formula [1a-8] are preferred. Formula [1a-1], formula [1a-2], and formula [1a-4] to formula [1a-6] are more preferred. Formula [1a-1], formula [1a-2], formula [1a-4], and formula [1a-5] are particularly preferred.

[0031] From the viewpoint of optimally achieving the effects of the present invention, the proportion XA of the specific diamine used is preferably 40 to 100 mol % relative to the total diamine component. It is more preferably 50 to 100 mol %, and particularly preferably 60 to 100 mol %. Furthermore, the specific diamine can be used alone or in combination of two or more types depending on the properties.

[0032] The diamine component can use diamines other than the specific diamines as other diamines. Specific examples include the other diamine compounds described in paragraphs

[0044] to

[0051] of WO 2013 / 125595, the diamines of formulas (Y-1) to (Y-167) described in paragraphs

[0062] to

[0080] of WO 2018 / 117239, and the diamines of formulas [DA-1] to [DA-103] below. Furthermore, the other diamines can be used alone or in combination of two or more depending on the properties.

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044] In the method for introducing the specific structure (2) into a polyimide-based polymer, it is preferable to use a tetracarboxylic acid anhydride having the specific structure (2) or a derivative thereof as part of a raw material. In particular, it is preferable to use a tetracarboxylic acid anhydride or a derivative thereof represented by the following formula [2-1a] (hereinafter also referred to as a "specific tetracarboxylic acid"):

[0045]

[0046] Y in formula [2-1a] １ , Y ２ , R ５ ~R ８The details of r5 to r8 and the preferred combinations are as described above. More specifically, the specific tetracarboxylic acid of the following formula [2-2a] can be mentioned.

[0047]

[0048] Y ａ and Y ｂ are each a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or Y ａ and Y ｂ and *-Y-* (Y is a single bond or an oxygen atom. * is a bond to the benzene ring) are combined together. Among them, hydrogen atoms, halogen atoms other than fluorine atoms, methyl groups, or Y ａ and Y ｂ and *-Y-* are preferably combined with each other. ５ ~R ８ each represents an alkyl group having 1 to 20 carbon atoms, fluorine, or a trifluoromethyl group. Of these, a methyl group or an ethyl group is preferred. r5 to r8 each represent an integer of 0 to 2. Of these, an integer of 0 or 1 is preferred. 0 is more preferred.

[0049] Specific examples of the specific tetracarboxylic acid include those represented by the following formulae [2a-1] to [2a-3], and it is preferable to use these in order to suitably obtain the effects of the present invention.

[0050]

[0051] From the viewpoint of optimally achieving the effects of the present invention, the proportion YA of the specific tetracarboxylic acid used is preferably 40 to 100 mol % relative to the total tetracarboxylic acid component. It is more preferably 50 to 100 mol %. It is particularly preferably 60 to 100 mol %. Furthermore, the specific tetracarboxylic acid can be used alone or in combination of two or more types depending on the properties. Tetracarboxylic acid anhydrides and derivatives thereof other than the specific tetracarboxylic acid can also be used as other tetracarboxylic acids in the tetracarboxylic acid component. Specific examples include tetracarboxylic acid anhydrides and derivatives thereof represented by the following formula [3]:

[0052] Z represents at least one selected from the structures of the following formulae [3a] to [3l].

[0053] (Z Ａ ~Z Ｄ represents a hydrogen atom, a methyl group, a chlorine atom, or a benzene ring. Ｅ and Z Ｆ each represents a hydrogen atom or a methyl group.

[0054] Examples of the other tetracarboxylic acids include the other tetracarboxylic acid components described in paragraph

[0057] of WO 2015 / 012368, and tetracarboxylic dianhydrides and derivatives thereof represented by the following formulae [CA-1] to [CA-26]. The other tetracarboxylic acids can be used alone or in combination of two or more depending on the properties.

[0055]

[0056]

[0057]

[0058] From the viewpoint of suitably obtaining the effects of the present invention, the specific polymer is preferably a polyimide-based polymer obtained by reacting a diamine component containing a specific diamine with a tetracarboxylic acid component containing a specific tetracarboxylic acid.

[0059] The ratio XA of the specific diamine to the ratio YA of the specific tetracarboxylic acid is preferably 40 mol%≦XA+YA≦200 mol%, more preferably 80 mol%≦XA+YA≦200 mol%, and particularly preferably 140 mol%≦XA+YA≦200 mol%.

[0060] The method for synthesizing the polyimide polymer is not particularly limited. It is usually obtained by reacting a diamine component with a tetracarboxylic acid component. Specific examples include the method described in paragraphs

[0059] and

[0059] of WO 2015 / 012368. Polyamic acid esters can be synthesized by known methods, such as reacting a polyamic acid of a polyimide precursor obtained by reacting a diamine component with a tetracarboxylic acid component with an esterifying agent, reacting the tetracarboxylic acid diester with a diamine, or reacting the tetracarboxylic acid diester with a dihalide.

[0061] The solvent used in the reaction between the diamine component and the tetracarboxylic acid component is not particularly limited as long as it dissolves the produced polyimide precursor. Specific examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,3-dimethyl-imidazolidinone. Furthermore, when the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulae [D1] to [D3] can be used.

[0062] (D １ and D ２ represents an alkyl group having 1 to 3 carbon atoms. ３ represents an alkyl group having 1 to 4 carbon atoms.)

[0063] These may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyimide precursor, it may be mixed with the above-mentioned solvent to the extent that it does not precipitate. Furthermore, since moisture in the solvent inhibits the polymerization reaction and further causes hydrolysis of the polyimide precursor, it is preferable to use a solvent that has been dehydrated and dried.

[0064] In the polymerization reaction of the polyimide precursor, the total number of moles of the tetracarboxylic acid components is preferably 0.8 to 1.2 when the total number of moles of the diamine components is 1.0. When the total number of moles of the tetracarboxylic acid components is less than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is smaller than the number of moles of the diamine components, the polymer will have an amino group structure at its terminal. When the total number of moles of the tetracarboxylic acid components is greater than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is greater than the number of moles of the diamine components, the polymer will have a carboxylic anhydride or dicarboxylic acid structure at its terminal. Polyimides are obtained by ring-closing a polyimide precursor, and the imidization rate does not necessarily need to be 100% and can be adjusted as desired depending on the application and purpose. From the viewpoint of solubility in solvents, a ratio of 30 to 90% is preferred. A ratio of 40 to 90% is even more preferred.

[0065] The polyimide polymer may be converted into a terminal-capping polymer using a terminal-capping agent. The terminal-capping polymer has the effect of increasing the film hardness of the liquid crystal alignment film and improving the adhesion between the liquid crystal alignment film and the sealant in the liquid crystal light control element. The method for obtaining the terminal-capping polymer is not particularly limited. Specific examples include the methods described in paragraphs

[0046] and

[0047] of WO 2023 / 074568.

[0066] From the viewpoints of the strength of the liquid crystal alignment film obtained therefrom, workability during film formation, and coating properties, the molecular weight of the polyimide polymer is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000, in terms of polyethylene glycol oxide (Mw) measured by Gel Permeation Chromatography (GPC).

[0067] <Liquid Crystal Alignment Agent> The liquid crystal alignment agent is a solution for forming a liquid crystal alignment film, and is a solution containing a specific polymer and a solvent. In this case, two or more types of specific polymers can be used. The polymer components do not all have to be specific polymers, and polymers not having specific structure (1) or specific structure (2) may be mixed. In this case, the proportion of these polymers not having specific structures used is preferably 10 to 200 parts by mass per 100 parts by mass of the specific polymer. More preferably, it is 10 to 100 parts by mass.

[0068] The content of the solvent in the liquid crystal aligning agent can be appropriately selected from the viewpoint of the application method of the liquid crystal aligning agent and obtaining a desired film thickness. In particular, from the viewpoint of forming a uniform liquid crystal alignment film by application, the content of the solvent in the liquid crystal aligning agent is preferably 50 to 99.9% by mass, more preferably 60 to 99% by mass, and particularly preferably 65 to 99% by mass.

[0069] The solvent used for the liquid crystal aligning agent is not particularly limited as long as it is a solvent that can dissolve the specific polymer. Among them, the following solvents (hereinafter also referred to as "Solvent A") are preferably used. For example, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N,N-dimethylpropionamide, tetramethylurea, N,N-diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropanamide, Examples of suitable solvents include 3-butoxy-N,N-dimethylpropanamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone (hereinafter, these are also collectively referred to as "good solvents"). Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, and γ-butyrolactone are preferred. These solvents may be used alone or in combination of two or more.

[0070] When the specific polymer has high solubility in the solvent, the following solvent (hereinafter also referred to as "Solvent B") can be used.For example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2-(2-butoxyethoxy) (oxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monopropyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, ethylene glycol monoethyl ether, n-butyl acetate, propylene glycol monoethyl ether acetate, cyclohexyl acetate, 4-methyl-2-pentyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, or diisobutyl ketone (2,6-dimethyl-4-heptanone).Among these, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or diisobutyl ketone are preferably used. These may be used alone or in combination of two or more.

[0071] In the present invention, from the viewpoint of the coating properties of the liquid crystal alignment film, it is preferable to use a solvent that is a combination of Solvent A and Solvent B. Specific examples include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-diphenyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolact ...methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-buty Methyl lactamide and diisobutyl ketone, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone, ethyl 3-ethoxypropionate and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N -Ethyl-2-pyrrolidone, ethyl 3-ethoxypropionate, and diethylene glycol monopropyl ether, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate, N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether, N,N-dimethyl lactamide and ethylene glycol monobutyl ether, N,N-dimethyl lactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone N-methyl-2-pyrrolidone, diethylene glycol monomethyl ether, and butyl cellosolve acetate, N-methyl-2-pyrrolidone, diethylene glycol monomethyl ether, and butyl cellosolve acetate, N,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, and 4-hydroxy-4-methyl-2-pentanone,N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether Methyl-2-pentanone and propylene glycol diacetate, N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol dimethyl ether, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutyl ketone, N-methyl-2-pi rolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutylcarbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol pyrene glycol monomethyl ether, N-ethyl-2-pyrrolidone, diethylene glycol diethyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and propylene glycol diacetate, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and diisobutyl ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone, and diisobutyl ketone, N-ethyl-2-pyrrolidone, N,N-dimethyl lactamide, and diisobutyl ketone,Examples of the combination include N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether acetate, γ-butyrolactone, ethylene glycol monobutyl ether acetate, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether acetate, and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone, 4-methyl-2-pentyl acetate, and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone, cyclohexyl acetate, and 4-hydroxy-4-methyl-2-pentanone, cyclohexanone, and propylene glycol monomethyl ether, cyclopentanone, and propylene glycol monomethyl ether, and N-methyl-2-pyrrolidone, cyclohexanone, and propylene glycol monomethyl ether, and combinations of these are preferred.

[0072] When the solvent A type and the solvent B type are used in combination, the solvent B type is preferably 1 to 99 mass % of the total solvent contained in the liquid crystal aligning agent, more preferably 10 to 99 mass %, and most preferably 20 to 95 mass %.

[0073] In order to increase the film strength of the liquid crystal alignment film, the liquid crystal aligning agent preferably contains a compound having at least one structure selected from an epoxy group, an isocyanate group, an oxetanyl group, an oxazoline group, a cyclocarbonate group, a hydroxy group, a hydroxyalkyl group, a lower alkoxyalkyl group, and a polymerizable unsaturated group (hereinafter collectively referred to as a "crosslinkable compound"). In this case, the compound must contain two or more of these groups.

[0074] Specific examples of the crosslinkable compound having an epoxy group or an isocyanate group include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, bisphenol A type epoxy resins such as Epicoat 828 (manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins such as Epicoat 807 (manufactured by Mitsubishi Chemical Corporation), YX-8000 (manufactured by Mitsubishi Chemical Corporation), ), biphenyl skeleton-containing epoxy resins such as YX6954BH30 (manufactured by Mitsubishi Chemical Corporation), phenol novolac epoxy resins such as EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), (o, m, p-) cresol novolac epoxy resins such as EOCN-102S (manufactured by Nippon Kayaku Co., Ltd.), compounds in which a tertiary nitrogen atom is bonded to an aromatic carbon atom such as tetrakis(glycidyloxymethyl)methane, N,N,N',N'-tetraglycidyl-1,4-phenylenediamine, N,N,N',N'-tetraglycidyl-2,2'-dimethyl-4.4'-diaminobiphenyl, 2,2-bis[4-(N,N-diglycidyl-4-aminophenoxy)phenyl]propane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane;N,N,N',N'-tetraglycidyl-1,2-diaminocyclohexane, N,N,N',N'-tetraglycidyl-1,3-diaminocyclohexane, N,N,N',N'-tetraglycidyl-1,4-diaminocyclohexane, bis(N,N-diglycidyl-4-aminocyclohexyl)methane, bis(N,N-diglycidyl-2-methyl-4-aminocyclohexyl)methane, bis(N,N-diglycidyl-3-methyl-4-aminocyclohexyl)methane, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,4-bis(N,N-diglycidylaminomethyl)cyclohexane, 1 ,3-bis(N,N-diglycidylaminomethyl)benzene, 1,4-bis(N,N-diglycidylaminomethyl)benzene, 1,3,5-tris(N,N-diglycidylaminomethyl)cyclohexane, 1,3,5-tris(N,N-diglycidylaminomethyl)benzene and other compounds in which a tertiary nitrogen atom is bonded to an aliphatic carbon atom; isocyanurate compounds such as triglycidyl isocyanurate such as TEPIC (manufactured by Nissan Chemical Industries, Ltd.); and those described in paragraph

[0037] of Japanese Patent Laid-Open Publication No. 10-338880 and paragraphs

[0051] to

[0054] of WO2017 / 170483.

[0075] Specific examples of the crosslinkable compound having an oxetanyl group include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene (Aronoxetane OXT-121 (XDO)), bis[2-(3-oxetanyl)butyl]ether (Aronoxetane OXT-221 (DOX)), 1,4-bis[(3-ethyloxetan-3-yl)methoxy]benzene (HQOX), 1,3-bis[(3-ethyloxetan-3-yl)methoxy]benzene (RSOX), 1,2-bis[(3-ethyloxetan-3-yl)methoxy]benzene (CTOX), and those described in paragraphs

[0170] to

[0175] of WO2011 / 132751.

[0076] Specific examples of crosslinkable compounds having an oxazoline group include compounds such as 2,2'-bis(2-oxazoline) and 2,2'-bis(4-methyl-2-oxazoline), polymers and oligomers having an oxazoline group such as EPOCROS (manufactured by Nippon Shokubai Co., Ltd.), and those described in paragraph

[0115] of Japanese Patent Publication No. 2007-286597. Specific examples of crosslinkable compounds having a cyclocarbonate group include N,N,N',N'-tetra[(2-oxo-1,3-dioxolan-4-yl)methyl]-4,4'-diaminodiphenylmethane, N,N'-di[(2-oxo-1,3-dioxolan-4-yl)methyl]-1,3-phenylenediamine, and those described in paragraphs

[0025] to

[0030] and

[0032] of WO2011 / 155577.

[0077] Specific examples of crosslinkable compounds having a blocked isocyanate group include Coronate AP Stable M, Coronate 2503, 2515, 2507, 2513, 2555, and Millionate MS-50 (manufactured by Tosoh Corporation), Takenate B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, and B-882N (manufactured by Mitsui Chemicals, Inc.), and those described in paragraphs

[0046] to

[0047] of Japanese Patent Publication No. 2014-224978 and paragraphs

[0119] to

[0120] of WO2015 / 141598.

[0078] Specific examples of crosslinkable compounds having a hydroxy group, a hydroxyalkyl group, or a lower alkoxyalkyl group include N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethoxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)-1,1,1,3,3,3-hexafluoropropane, and those described in paragraph

[0058] of Japanese Patent Publication No. 2016-118753, paragraph

[0055] of Japanese Patent Publication No. 2016-200798, and paragraphs

[0017] to

[0029] of WO2010 / 074269.

[0079] Specific examples of crosslinkable compounds having a polymerizable unsaturated group include glycerin mono(meth)acrylate, glycerin di(meth)acrylate (1,2-, 1,3-mixture), glycerin tris(meth)acrylate, glycerol 1,3-diglycerolate di(meth)acrylate, pentaerythritol tri(meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, pentaethylene glycol mono(meth)acrylate, and hexaethylene glycol mono(meth)acrylate. The proportion of the crosslinkable compound used in the liquid crystal aligning agent is preferably 0.1 to 100 parts by mass relative to 100 parts by mass of all polymer components. From the viewpoint of promoting the crosslinking reaction and achieving the desired effect, a proportion of 0.1 to 50 parts by mass is more preferred. A proportion of 1 to 30 parts by mass is particularly preferred.

[0080] The liquid crystal aligning agent may be a compound that improves the uniformity of the thickness and surface smoothness of the liquid crystal alignment film, or a compound that improves the adhesion between the liquid crystal alignment film and the substrate. Examples of compounds that improve the uniformity of the thickness and surface smoothness of the liquid crystal alignment film include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. Specific examples include the surfactants described in paragraph

[0122] of WO 2014 / 171493. The amount of the surfactant used is preferably 0.01 to 2 parts by mass relative to 100 parts by mass of all polymer components. A range of 0.01 to 1 part by mass is more preferred.

[0081] Specific examples of compounds that improve the adhesion between a liquid crystal alignment film and a substrate include the compounds described in paragraph

[0123] of WO2014 / 171493. More specific examples include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. Examples of suitable compounds include glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane. The amount of such compounds used is preferably 0.1 to 30 parts by mass relative to 100 parts by mass of all polymer components. A more preferred amount is 1 to 20 parts by mass. In addition to the compounds listed above, the liquid crystal aligning agent may contain a dielectric or conductive substance added for the purpose of changing the electrical properties, such as the dielectric constant and conductivity, of the liquid crystal alignment film.

[0082] <Liquid Crystal Alignment Film / Liquid Crystal Light Control Element> A liquid crystal alignment agent can be applied to a substrate, baked, and then, if necessary, subjected to alignment treatment such as rubbing or photo-alignment treatment, to be used as a liquid crystal alignment film. The liquid crystal alignment film of the present invention has the function of aligning liquid crystal molecules approximately horizontally. The approximately horizontal alignment refers to, for example, a state in which the tilt angle of the liquid crystal molecules with respect to the surface of the substrate with the liquid crystal alignment film is in the range of 0 to 20°, or a state in which a liquid crystal cell is sandwiched between two polarizing plates in a crossed Nicol arrangement so that the polarization axes of the polarizing plates are perpendicular to each other, and light is transmitted when irradiated from one side of the liquid crystal cell.

[0083] The substrate used to form the liquid crystal alignment film is not particularly limited as long as it is a highly transparent substrate. In addition to glass substrates, plastic substrates such as acrylic substrates, polycarbonate substrates, and PET (polyethylene terephthalate) substrates, as well as films thereof, can be used. In particular, plastic substrates and films are preferred when used in light control windows, etc. From the viewpoint of process simplification, it is preferable to use a substrate on which an ITO (indium tin oxide) electrode, an IZO (indium zinc oxide) electrode, an IGZO (indium gallium zinc oxide) electrode, an organic conductive film, or the like is formed for driving the liquid crystal. Furthermore, when a reflective liquid crystal light control element is formed, a substrate on which a silicon wafer, a metal such as aluminum, or a dielectric multilayer film is formed can be used as the substrate on only one side.

[0084] The liquid crystal light control element has a liquid crystal alignment film on at least one of the substrates, which has the function of aligning liquid crystal molecules substantially horizontally. In the present invention, it is preferable that both substrates have liquid crystal alignment films.

[0085] The method for applying the liquid crystal aligning agent is not particularly limited, but industrially, a dipping method, a roll coater method, a slit coater method, a spinner method, a spray method, a screen printing method, an offset printing method, a flexographic printing method, an inkjet method, or the like is used. These application methods are used depending on the purpose. After applying the liquid crystal aligning agent to the substrate, the solvent can be evaporated using a heating means such as a hot plate, a hot air circulation oven, or an IR (infrared) oven at a temperature of 30 to 300°C, preferably 30 to 250°C, depending on the type of substrate and the solvent used in the liquid crystal aligning agent, to form a liquid crystal alignment film. When a plastic substrate is used as the substrate, treatment at a temperature of 30 to 150°C is preferred.

[0086] The thickness of the liquid crystal alignment film is preferably 5 to 500 nm, more preferably 10 to 300 nm, and particularly preferably 10 to 250 nm, since too thick a film can be disadvantageous in terms of power consumption of the liquid crystal light control element, and too thin a film can reduce the reliability of the element. The thickness of the liquid crystal alignment film is preferably 5 to 500 nm, more preferably 10 to 300 nm, and particularly preferably 10 to 250 nm. The liquid crystal alignment film can be subjected to alignment treatments such as rubbing in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, or photoalignment in which the surface of the liquid crystal alignment film is irradiated with polarized radiation in a certain direction.

[0087] The liquid crystal composition contains a liquid crystal and a chiral compound. The liquid crystal may be a nematic liquid crystal, a smectic liquid crystal, or a cholesteric liquid crystal. Among these, it is preferable to use a nematic liquid crystal having a positive dielectric anisotropy.

[0088] From the viewpoint of low-voltage operation, liquid crystals having large dielectric anisotropy and large refractive index anisotropy are preferred. Furthermore, liquid crystals can be used singly or in combination of two or more types depending on the physical properties of the phase transition temperature, dielectric anisotropy, and refractive index anisotropy. To operate a liquid crystal dimming element as an active element such as a thin film transistor (TFT), the liquid crystal is required to have high electrical resistance and a high voltage holding ratio (hereinafter also referred to as "VHR"). Therefore, it is preferable to use fluorine-based or chlorine-based liquid crystals, which have high electrical resistance and whose VHR is not reduced by active energy rays such as ultraviolet rays.

[0089] The chiral compound induces a helical structure in nematic liquid crystal, and known compounds can be used. Specific examples include Schiff compounds, azoxy compounds, biphenyl compounds, phenyl ester compounds, phenylcyclohexane compounds, and pyridine compounds, as well as mixtures thereof. More specific examples include S-811, R811, and CB-15 (manufactured by Merck). Furthermore, chiral compounds can be used singly or in combination, depending on their properties. The proportion of chiral compounds used can be adjusted so that the desired d / p ratio is achieved, where d is the thickness of the liquid crystal layer in the liquid crystal dimming element, and p is the chiral pitch of the liquid crystal in the liquid crystal layer (the distance required for one liquid crystal molecule to twist one period). In the present invention, d / p is preferably 1 to 10, more preferably 1 to 8, and particularly preferably 1 to 6, in order to optimally obtain the effects of the present invention.

[0090] The liquid crystal composition preferably contains a dichroic dye in addition to the liquid crystal and the chiral compound. This causes the dichroic dye to change direction by 90° along the direction of the liquid crystal director (orientation direction) depending on whether or not a voltage is applied, resulting in a difference in the absorption characteristics of the dichroic dye, thereby achieving a difference in total light transmittance. The dichroic dye preferably has a maximum absorption wavelength in the visible light region, for example, in the region of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, phthalocyanine dyes, azo dyes, and anthraquinone dyes. Among these, phthalocyanine dyes, azo dyes, and anthraquinone dyes are preferably used. Specific examples of dichroic dyes include G-207, G-241, G-470 (all manufactured by Hayashibara Co., Ltd.), Yellow-8, KRD-901, KRD-902 (all manufactured by Showa Chemical Industry Co., Ltd.), SI-486, M-1012 (manufactured by Mitsui Chemicals, Inc.), Dichroic Dye Blue AB2, AB3, AB4, Dichroic Dye Cyan AC1, Dichroic Dye Orange AO1, AZO1, Dichroic Dye Red AR1, and Dichroic Dye Yellow AG1 (all manufactured by NEMATEL). Furthermore, one type of dichroic dye can be used, or two or more types can be mixed together, depending on the properties of the dye.

[0091] The dichroic dye is preferably used in an amount of 0.01 to 10 parts by mass relative to 100 parts by mass of liquid crystal, and more preferably 0.1 to 5 parts by mass from the viewpoint of the difference between colorless transparency and colored (hereinafter also referred to as "contrast of total light transmittance").

[0092] The liquid crystal light control element of the present invention differs from the PSA (Polymer Sustained Alignment) system, PDLC (Polymer Dispersed Liquid Crystal) system, and PNLC (Polymer Network Liquid Crystal) system, and therefore does not contain a polymerizable compound that reacts with light or heat, which is required for these systems. The liquid crystal composition can be prepared by mixing a liquid crystal, a chiral compound, and a dichroic dye. In this case, heating is preferably performed during preparation from the viewpoint of the solubility of the dichroic dye in the liquid crystal. Specifically, heating is preferably performed to a temperature not exceeding the phase transition temperature of the liquid crystal.

[0093] The method for injecting the liquid crystal composition is not particularly limited, and examples thereof include the following methods. That is, when glass substrates are used as the substrates, a pair of substrates on which a liquid crystal alignment film is formed is prepared, and a sealant is applied to four edges of one substrate, excluding a portion. Thereafter, the other substrate is attached to the pair of substrates with the liquid crystal alignment film facing inward to prepare an empty cell. The liquid crystal composition is then injected under reduced pressure from the area where the sealant is not applied to obtain a liquid crystal composition-injected cell. Furthermore, when plastic substrates or films are used as the substrates, a pair of substrates on which a liquid crystal alignment film is formed is prepared, and the liquid crystal composition is dropped onto one substrate by an ODF (One Drop Filling) method, an inkjet method, or the like, and then the other substrate is attached to the pair of substrates to obtain a liquid crystal composition-injected cell.

[0094] The method for controlling the thickness of the liquid crystal layer (hereinafter also referred to as "gap") of the liquid crystal dimming element is not particularly limited, and examples thereof include a method of introducing spacers of a desired size into the liquid crystal composition, a method of applying the liquid crystal composition onto a substrate having column spacers of a desired size, or a method of using a liquid crystal composition containing column spacers of a desired size. From the viewpoint of optimally achieving the effects of the present invention, the thickness of the liquid crystal layer is preferably 1 to 100 μm, more preferably 1 to 75 μm, and particularly preferably 1 to 30 μm. If the gap is too small, the contrast of the liquid crystal dimming element will decrease, and if it is too large, the driving voltage of the element will increase.

[0095] In order to increase the contrast of the total light transmittance of the liquid crystal light control element of the present invention, a polarizing plate can be attached to the outer surface thereof.

[0096] The present invention will be described in more detail below with reference to examples, but is not limited to these examples.

[0097] "Abbreviations used in Synthesis Examples, Examples, and Comparative Examples" <Monomers for preparing polyimide polymers> (Specific diamines) A1: Diamines of the following formula [A1]

[0098]

[0099] (Other diamines) B1 to B4: Diamines of the following formulas [B1] to [B4]

[0100]

[0101] (Specific tetracarboxylic acid) C1: tetracarboxylic dianhydride represented by the following formula [C1]

[0102]

[0103] (Other tetracarboxylic acids) D1 to D2: tetracarboxylic dianhydrides of the following formulas [D1] to [D2]

[0104]

[0105] <Crosslinkable Compounds> K1 to K3: Crosslinkable compounds of the following formulae [K1] to [K3]

[0106]

[0107] <Solvent> NMP: N-methyl-2-pyrrolidone NEP: N-ethyl-2-pyrrolidone BCS: Ethylene glycol monobutyl ether PB: Propylene glycol monobutyl ether

[0108] "Molecular Weight Measurement" The number average molecular weight (hereinafter also referred to as "Mn") and weight average molecular weight (hereinafter also referred to as "Mw") of the polyimide polymer were measured using the following apparatus and conditions. Room temperature gel permeation chromatography (GPC) apparatus: GPC-101 (manufactured by Resonac Corporation) Column: GPC KD-803 and KD-805 (manufactured by Resonac Corporation) in series Column temperature: 50°C Eluent: N,N-dimethylformamide (containing lithium bromide monohydrate (LiBr.H) as an additive) ２ o-Phosphoric acid (o-Phosphoric acid) 30 mmol / L, tetrahydrofuran (THF) 10 ml / L) Flow rate: 1.0 mL / min Standard sample for creating a calibration curve: EasiVial PEG / PEO polyethylene glycol oxide PL2080-0201 (molecular weight: approximately 1,500, approximately 4,000, approximately 13,000, approximately 30,000, approximately 70,000, approximately 130,000, approximately 500,000, approximately 1,000,000, approximately 1,500,000) (GL Sciences)

[0109] Synthesis of Polyimide Polymers Synthesis Example 1: A1 (3.09 g, 8.87 mmol), C1 (4.00 g, 8.73 mmol), and NMP (21.3 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was allowed to react at 40°C for 6 hours while nitrogen was being supplied, yielding a polyamic acid solution (1) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 23,600 and an Mw of 65,700. Synthesis Example 2: A1 (1.54 g, 4.42 mmol), B1 (0.48 g, 4.44 mmol), C1 (4.00 g, 8.73 mmol), and NEP (18.1 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was allowed to react at 40°C for 6 hours while nitrogen was being supplied, yielding a polyamic acid solution (2) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 21,300 and an Mw of 61,200.

[0110] Synthesis Example 3: A1 (2.47 g, 7.09 mmol), B2 (0.73 g, 1.78 mmol), C1 (4.00 g, 8.73 mmol), and NMP (21.6 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40° C. for 6 hours while supplying nitrogen to obtain a polyamic acid solution (3) with a resin solids concentration of 25% by mass. The Mn of this polyamic acid was 24,500 and the Mw was 72,300. Synthesis Example 4: A1 (1.85 g, 5.31 mmol), B1 (0.29 g, 2.68 mmol), B3 (0.34 g, 0.90 mmol), C1 (4.00 g, 8.73 mmol), and NEP (19.4 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40° C. for 6 hours while supplying nitrogen, to obtain a polyamic acid solution (4) with a resin solids concentration of 25% by mass. The Mn of this polyamic acid was 19,200 and the Mw was 63,200.

[0111] Synthesis Example 5: B1 (1.20 g, 11.1 mmol), C1 (5.00 g, 10.9 mmol), and NMP (18.6 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was allowed to react at 40°C for 6 hours while nitrogen was being supplied, yielding a polyamic acid solution (5) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 25,100 and an Mw of 70,300. Synthesis Example 6: B2 (3.18 g, 7.75 mmol), C1 (3.50 g, 7.63 mmol), and NMP (20.0 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was allowed to react at 40°C for 6 hours while nitrogen was being supplied, yielding a polyamic acid solution (6) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 23,700 and an Mw of 68,000.

[0112] Synthesis Example 7: A1 (2.57 g, 7.38 mmol), B1 (0.20 g, 1.85 mmol), C1 (2.50 g, 5.45 mmol), and NMP (10.5 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40°C for 4 hours while nitrogen was being introduced. Subsequently, D1 (1.07 g, 3.64 mmol) and NMP (8.56 g) were added, and the mixture was reacted at 40°C for 6 hours, yielding a polyamic acid solution (7) with a resin solids concentration of 25% by mass. The Mn of this polyamic acid was 18,600 and the Mw was 58,900. Synthesis Example 8 A 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube was charged with A1 (3.61 g, 10.4 mmol), D1 (3.00 g, 10.2 mmol), and NMP (19.8 g), and the mixture was reacted at 40° C. for 6 hours while supplying nitrogen to obtain a polyamic acid solution (8) having a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 23,800 and an Mw of 70,700.

[0113] Synthesis Example 9: A1 (2.88 g, 8.27 mmol), B1 (0.22 g, 2.03 mmol), D1 (3.00 g, 10.2 mmol), and NMP (18.3 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40°C for 6 hours while nitrogen was supplied to obtain a polyamic acid solution (9) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 21,800 and an Mw of 67,100. Synthesis Example 10: A1 (4.51 g, 12.9 mmol), D2 (2.50 g, 12.7 mmol), and NMP (21.0 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40°C for 6 hours while nitrogen was supplied to obtain a polyamic acid solution (10) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 24,900 and an Mw of 72,100.

[0114] Synthesis Example 11: A1 (3.61 g, 10.4 mmol), B2 (1.06 g, 2.58 mmol), D1 (0.75 g, 2.55 mmol), and NMP (11.9 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40 ° C. for 2 hours while nitrogen was being introduced. Subsequently, D2 (2.00 g, 10.2 mmol) and NMP (9.75 g) were added, and the mixture was reacted at 40 ° C. for 6 hours, yielding a polyamic acid solution (11) with a resin solids concentration of 25% by mass. The Mn of this polyamic acid was 21,800, and the Mw was 65,300. Synthesis Example 12: B1 (1.87 g, 17.3 mmol), D1 (5.00 g, 17.0 mmol), and NMP (20.6 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40° C. for 6 hours while supplying nitrogen to obtain a polyamic acid solution (12) with a resin solids concentration of 25% by mass. The Mn of this polyamic acid was 25,300 and the Mw was 73,100.

[0115] Synthesis Example 13: B4 (2.74 g, 13.8 mmol), D1 (4.00 g, 13.6 mmol), and NMP (20.2 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40 ° C. for 6 hours while nitrogen was supplied, yielding a polyamic acid solution (13) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 28,100 and an Mw of 70,100. Synthesis Example 14: B1 (2.52 g, 23.3 mmol), D2 (4.50 g, 22.9 mmol), and NMP (21.1 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was reacted at 40 ° C. for 6 hours while nitrogen was supplied, yielding a polyamic acid solution (14) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 25,000 and an Mw of 72,500.

[0116] Synthesis Example 15: B4 (3.59 g, 18.1 mmol), D2 (3.50 g, 17.8 mmol), and NMP (21.3 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was allowed to react at 40° C. for 6 hours while supplying nitrogen, yielding a polyamic acid solution (15) with a resin solids concentration of 25% by mass. The polyamic acid had an Mn of 23,100 and an Mw of 69,200. The specifications of the polyimide polymer obtained above are shown in Tables 1 and 2.

[0117]

[0118]

[0119] "Preparation of Liquid Crystal Alignment Agents" Examples 1 to 14 and Comparative Examples 1 to 4 below describe preparation examples of liquid crystal alignment agents. These liquid crystal alignment agents are used for evaluation of liquid crystal light control devices. The specifications of the liquid crystal alignment agents are shown in Tables 3 and 4.

[0120]

[0121] *1: Indicates the amount (parts by mass) of crosslinkable compound introduced relative to 100 parts by mass of polyimide polymer.

[0122] "Confirmation of the nearly horizontal alignment of the liquid crystal alignment film" The liquid crystal alignment agent obtained by the method of the examples and comparative examples was pressure-filtered through a membrane filter with a pore size of 1 μm, and spin-coated on the ITO surface of a substrate (40 mm long x 30 mm wide, 0.7 mm thick) with an ITO electrode that had been washed with pure water and IPA (isopropanol). The substrate was then heated at 80°C for 2 minutes on a hot plate and at 230°C for 20 minutes in a hot air circulation clean oven to obtain an ITO substrate with a liquid crystal alignment film having a film thickness of 100 nm. Next, the liquid crystal alignment film surface of this substrate was rubbed using a rubbing device with a roll diameter of 120 mm using a rayon cloth under the conditions of a roll rotation speed of 1000 rpm, a roll advance speed of 50 mm / sec, and a push-in depth of 0.3 mm. Next, two ITO substrates with liquid crystal alignment films were prepared. 12 μm spacers were sprayed onto the liquid crystal alignment film surface of one substrate. A sealant (XN-5490H) (manufactured by Kyoritsu Chemical Industry Co., Ltd.) was applied to the liquid crystal alignment film surface on all four sides of the other substrate. These substrates were then bonded together so that the liquid crystal alignment film surfaces of the substrates faced each other and the rubbing directions faced each other, i.e., in an antiparallel orientation. The bonded substrates were pressed together and heated at 80°C for 15 minutes, then at 150°C for 90 minutes to prepare an empty cell. A positive liquid crystal (PA-1492, manufactured by DIC Corporation) was injected into this empty cell by a reduced pressure injection method. The injection port was then sealed, and the cell was heated at 120°C for 30 minutes to obtain a liquid crystal cell. Next, the liquid crystal cell was sandwiched between two polarizing plates so that the polarization axes of the two plates were perpendicular to each other. A backlight was irradiated from one side of the liquid crystal cell to confirm the liquid crystal cell. As a result, it was confirmed that the liquid crystal was aligned almost horizontally in all the liquid crystal cells.

[0123] "Preparation of Liquid Crystal Composition (A)" 10.0 g of Sb-408030L (positive liquid crystal containing a chiral compound, chiral pitch (p) = 4.0 μm) (manufactured by Champaign) and 0.2 g of M-1012 (manufactured by Mitsui Fine Chemicals, Inc.) were mixed and stirred at 23°C for 24 hours to obtain liquid crystal composition (A).

[0124] "Preparation of Liquid Crystal Cell (Liquid Crystal Light Control Element)" The liquid crystal alignment agent obtained by the method of the Examples and Comparative Examples was pressure-filtered through a membrane filter with a pore size of 1 μm, and spin-coated onto the ITO surface of a substrate (40 mm long x 30 mm wide, 0.7 mm thick) with an ITO electrode that had been washed with pure water and IPA. The substrate was then heated at 80°C for 2 minutes on a hot plate and at 230°C for 20 minutes in a hot air circulation clean oven to obtain an ITO substrate with a liquid crystal alignment film having a film thickness of 100 nm. Next, the liquid crystal alignment film surface of the substrate was rubbed using a rubbing device with a roll diameter of 120 mm using a rayon cloth under the following conditions: roll rotation speed: 1000 rpm, roll advancement speed: 50 mm / sec, and indentation depth: 0.3 mm. Then, two ITO substrates with liquid crystal alignment films were prepared. 12 μm spacers were sprayed onto the liquid crystal alignment film surface of one substrate. A sealant (XN-5490H) (manufactured by Kyoritsu Chemical Industry Co., Ltd.) was applied to the liquid crystal alignment film surface on all four sides of the other substrate. These substrates were then bonded together so that the liquid crystal alignment film surfaces of the substrates faced each other and the rubbing directions faced each other, i.e., in an antiparallel orientation. The bonded substrates were pressed together and subjected to a heat treatment at 80°C for 15 minutes and then at 150°C for 90 minutes to prepare an empty cell. Liquid crystal composition (A) was injected into this empty cell by a reduced pressure injection method. The injection port was then sealed, and the cell was subjected to a heat treatment at 120°C for 30 minutes to obtain a liquid crystal cell.

[0125] "Confirmation of Liquid Crystal Cell Display Defects" This evaluation was conducted to evaluate the in-plane transmittance uniformity of the liquid crystal cell due to poor alignment of the liquid crystal and dye. Specifically, an AC voltage of ±50 V was applied to the liquid crystal cell immediately after preparation and after light irradiation for 10 seconds, and then the AC voltage was returned to 0 V. The liquid crystal cell was then stacked on a polarizing plate, and the voltage was returned to 0 V. One minute later, the liquid crystal cell was inspected visually and with a polarizing microscope. A liquid crystal cell showing little in-plane transmittance variation and a uniform black display was evaluated as excellent in this evaluation. High uniformity refers to the absence of boundary regions where the in-plane transmittance is discontinuous (areas visible as spots or streaks).

[0126] More specifically, liquid crystal cells under the following conditions were observed. Condition A: Liquid crystal cell immediately after preparation. Condition B: Liquid crystal cell under condition A, to which an AC voltage of ±50 V was applied for 10 seconds, and then the AC voltage was returned to 0 V, and one minute had elapsed since then. Condition C: A film that cuts wavelengths of 380 nm or less was attached to the liquid crystal cell under condition B, and the light irradiation device was a Q-SUN Xenon Test Chamber Model Xe-1 (manufactured by Q-LAB Co., Ltd.) (0.55 W / m ２ Condition D: In Examples 3, 4, 6, 9, 11, 13 and 14, the liquid crystal cells of Condition C were further irradiated with light for 24 hours using the above-mentioned light irradiation device as an emphasis test. The results of confirming the in-plane transmittance uniformity of the liquid crystal cells are shown in Tables 5 and 6.

[0127] Example 1: NMP (20.3 g) and BCS (6.00 g) were added to polyamic acid solution (1) (5.00 g) obtained by the method of Synthesis Example 1, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (1). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (1), "preparation of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were performed. Example 2: K2 (0.063 g), NMP (20.3 g), and BCS (6.00 g) were added to polyamic acid solution (1) (5.00 g) obtained by the method of Synthesis Example 1, and the mixture was stirred at 25°C for 4 hours to obtain a liquid crystal aligning agent (2). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal alignment agent (2), "production of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0128] Example 3: NEP (20.3 g) and PB (6.00 g) were added to polyamic acid solution (2) (5.00 g) obtained by the method of Synthesis Example 2, and the mixture was stirred at 25°C for 2 hours to obtain liquid crystal aligning agent (3). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (3), "Preparation of a liquid crystal cell (liquid crystal light control element)" and "Confirmation of display defects of the liquid crystal cell" were performed. Example 4: NMP (20.3 g), BCS (3.00 g), and PB (3.00 g) were added to polyamic acid solution (3) (5.00 g) obtained by the method of Synthesis Example 3, and the mixture was stirred at 25°C for 2 hours to obtain liquid crystal aligning agent (4). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal alignment agent (4), "production of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0129] Example 5: To the polyamic acid solution (3) (5.00 g) obtained by the method of Synthesis Example 3, K1 (0.038 g), NMP (20.3 g), BCS (3.00 g), and PB (3.00 g) were added, and the mixture was stirred at 25°C for 4 hours to obtain a liquid crystal aligning agent (5). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (5), "Preparation of a liquid crystal cell (liquid crystal light control element)" and "Confirmation of display defects of the liquid crystal cell" were performed. Example 6: To the polyamic acid solution (4) (5.00 g) obtained by the method of Synthesis Example 4, NEP (20.3 g) and BCS (6.00 g) were added, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (6). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal alignment agent (6), "production of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0130] Example 7: NMP (20.3 g) and BCS (6.00 g) were added to the polyamic acid solution (5) (5.00 g) obtained by the method of Synthesis Example 5, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (7). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (7), "preparation of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out. Example 8: NMP (20.3 g) and BCS (6.00 g) were added to the polyamic acid solution (6) (5.00 g) obtained by the method of Synthesis Example 6, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (8). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (8), "preparation of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0131] Example 9: NMP (17.3 g) and BCS (9.00 g) were added to polyamic acid solution (7) (5.00 g) obtained by the method of Synthesis Example 7, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (9). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (9), "preparation of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out. Example 10: NMP (20.3 g) and BCS (6.00 g) were added to polyamic acid solution (8) (5.00 g) obtained by the method of Synthesis Example 8, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (10). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (10), "preparation of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0132] Example 11: NMP (17.3 g) and BCS (9.00 g) were added to 5.00 g of the polyamic acid solution (9) obtained by the method of Synthesis Example 9, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (11). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (11), "Preparation of a liquid crystal cell (liquid crystal light control element)" and "Confirmation of display defects of the liquid crystal cell" were performed. Example 12: NMP (20.3 g) and BCS (6.00 g) were added to 5.00 g of the polyamic acid solution (10) obtained by the method of Synthesis Example 10, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (12). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal alignment agent (12), "production of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0133] Example 13: NMP (20.3 g), BCS (3.00 g), and PB (3.00 g) were added to 5.00 g of the polyamic acid solution (11) obtained by the method of Synthesis Example 11, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (13). This liquid crystal aligning agent exhibited no abnormalities such as turbidity or precipitation, and was a homogeneous solution. Using the obtained liquid crystal aligning agent (13), "Preparation of a liquid crystal cell (liquid crystal light control element)" and "Confirmation of display defects of the liquid crystal cell" were performed. Example 14: K3 (0.088 g), NMP (17.3 g), BCS (6.00 g), and PB (3.00 g) were added to 5.00 g of the polyamic acid solution (11) obtained by the method of Synthesis Example 11, and the mixture was stirred at 25°C for 4 hours to obtain a liquid crystal aligning agent (14). This liquid crystal aligning agent exhibited no abnormalities such as turbidity or precipitation, and was a homogeneous solution. Using the obtained liquid crystal alignment agent (14), "production of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0134] Comparative Example 1: NMP (20.3 g) and BCS (6.00 g) were added to polyamic acid solution (12) (5.00 g) obtained by the method of Synthesis Example 12, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (15). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (15), "Preparation of a liquid crystal cell (liquid crystal light control element)" and "Confirmation of display defects of the liquid crystal cell" were performed. Comparative Example 2: NMP (20.3 g) and BCS (6.00 g) were added to polyamic acid solution (13) (5.00 g) obtained by the method of Synthesis Example 13, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (16). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal alignment agent (16), "production of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0135] Comparative Example 3: NMP (20.3 g) and BCS (6.00 g) were added to the polyamic acid solution (14) (5.00 g) obtained by the method of Synthesis Example 14, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (17). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal aligning agent (17), "Preparation of a liquid crystal cell (liquid crystal light control element)" and "Confirmation of display defects of the liquid crystal cell" were performed. Comparative Example 4: NMP (20.3 g) and BCS (6.00 g) were added to the polyamic acid solution (15) (5.00 g) obtained by the method of Synthesis Example 15, and the mixture was stirred at 25°C for 2 hours to obtain a liquid crystal aligning agent (18). This liquid crystal aligning agent was a homogeneous solution, with no abnormalities such as turbidity or precipitation. Using the obtained liquid crystal alignment agent (18), "production of a liquid crystal cell (liquid crystal light control element)" and "confirmation of display defects of the liquid crystal cell" were carried out.

[0136]

[0137] Good: There were no boundary regions where the transmittance was discontinuous (no spotted or streaky unevenness was observed). *1: A very small amount of spotted or streaky unevenness was observed. *2: Spotted or streaky unevenness was observed (more than *1). *3: Spotted or streaky unevenness was observed over the entire liquid crystal cell (more than *2).

[0138] As can be seen from the above results, the liquid crystal cells of the Examples had high in-plane transmittance uniformity immediately after preparation, after voltage application, and after light irradiation. That is, in Examples using a liquid crystal alignment film obtained from a liquid crystal alignment agent containing a polyimide-based polymer having specific structure (1) and / or specific structure (2), there were no boundary regions where the transmittance was discontinuous within the liquid crystal cell under conditions A, B, and C. Specifically, Examples 1 to 14 were compared with Comparative Examples 1 to 4. Furthermore, when the proportion of specific structure (1) and specific structure (2) in the polyimide-based polymer was high, the in-plane transmittance uniformity of the liquid crystal cell upon light irradiation was higher. That is, no boundary regions where the transmittance was discontinuous were observed within the liquid crystal cell under condition D, which was an emphasis test. Specifically, Examples 3, 4, and 9 were compared with Examples 11 and 13.

[0139] By using a liquid crystal aligning agent containing a polymer having a specific structure according to the present invention, a liquid crystal light control element with good liquid crystal alignment can be obtained. In particular, the liquid crystal light control element has properties that do not deteriorate even under harsh environments where the element is exposed to light for long periods of time. Therefore, the liquid crystal light control element of the present invention is useful in liquid crystal displays for display purposes, as well as light control windows and optical shutters that control the transmission and blocking of light.

[0140] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2024-097659 filed on June 17, 2024 are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. A liquid crystal light control element whose transmittance can be changed in response to the application of voltage, comprising: a pair of substrates each having an electrode; a liquid crystal layer provided between the substrates and containing liquid crystal molecules that are twistedly aligned when no voltage is applied; and a liquid crystal alignment film on at least one side between the substrates and the liquid crystal layer, the liquid crystal layer having the function of aligning the liquid crystal molecules approximately horizontally; wherein the liquid crystal layer contains a liquid crystal composition containing a liquid crystal having positive dielectric anisotropy and a chiral compound; the liquid crystal alignment film contains a polymer having at least one structure selected from the following formulas [1] and [2]; and wherein d / p is 1 to 10, where d is the thickness of the liquid crystal layer and p is the chiral pitch of the liquid crystal in the liquid crystal layer. (X １ and X ２ R each represents a single bond or a divalent organic group containing a benzene ring. １ ~R ４ Each represents an alkyl group having 1 to 20 carbon atoms, a halogen atom, or a trifluoromethyl group. Each of r1 to r4 represents an integer of 0 to 2. * represents a bond. (Y １ and Y ２ R each represents a single bond or a divalent organic group containing a benzene ring. ５ ~R ８ represents an alkyl group having 1 to 20 carbon atoms, fluorine, or trifluoromethyl group. r5 to r8 each represent an integer of 0 to 2. * represents a bond.

2. The liquid crystal light control device according to claim 1, wherein the polymer is at least one selected from the group consisting of a polyimide precursor obtained by reacting a diamine component with a tetracarboxylic acid component and a polyimide.

3. The liquid crystal light control element according to claim 2, wherein the polymer is at least one selected from a polyimide precursor and a polyimide obtained by reacting a diamine component containing a diamine having the structure of the formula [1] with a tetracarboxylic acid component containing a tetracarboxylic acid anhydride having the structure of the formula [2] or a derivative thereof.

4. The liquid crystal light control element according to claim 2 or 3, wherein the diamine component contains a diamine of the following formula [1-1a]: (X １ and X ２ R each represents a single bond or a divalent organic group containing a benzene ring. １ ~R ４ Each of r1 to r4 represents an integer of 0 to 2. A １ and A ２ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

5. The liquid crystal light control device according to claim 4, wherein the diamine is represented by the following formula [1-2a]: (X ３ and X ６ represents a benzene ring or a naphthalene ring. ４ and X ５ respectively represent a single bond, —O—, —CO—, —N(A)—, —COO—, —OCO—, —CON(A)— or —N(A)CO—, and A represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group or a 9-fluorenylmethyloxycarbonyl group. ａ and X ｂ are each a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or X ａ and X ｂ and m2 are bonded to each other to form *-X-* (X is a single bond or an oxygen atom, and * is a bond to the benzene ring). m1 and m2 each represent an integer of 0 to 2. R １ ~R ４ Each of r1 to r4 represents an integer of 0 to 2. A １ and A ２ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

6. The liquid crystal light control device according to claim 4, wherein the proportion XA of the diamine used is 40 to 100 mol % based on the total diamine components.

7. The liquid crystal light control element according to claim 2 or 3, wherein the tetracarboxylic acid component contains a tetracarboxylic acid anhydride of the following formula [2-1a] or a derivative thereof: (Y １ and Y ２ R each represents a single bond or a divalent organic group containing a benzene ring. ５ ~R ８ each represents an alkyl group having 1 to 20 carbon atoms, fluorine, or a trifluoromethyl group. r5 to r8 each represent an integer of 0 to 2.

8. The liquid crystal light control device according to claim 7, wherein the tetracarboxylic acid anhydride or a derivative thereof is represented by the following formula [2-2a]: (Y ａ and Y ｂ are each a hydrogen atom, a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or Y ａ and Y ｂ and *-Y-* (Y is a single bond or an oxygen atom. * is a bond to the benzene ring) combined together. ５ ~R ８ each represents an alkyl group having 1 to 20 carbon atoms, fluorine, or a trifluoromethyl group. r5 to r8 each represent an integer of 0 to 2.

9. The liquid crystal light control device according to claim 7, wherein the proportion YA of the tetracarboxylic anhydride or its derivative used is 40 to 100 mol % based on the total tetracarboxylic acid component.

10. The liquid crystal light control element according to claim 9, wherein the ratio XA of the diamine used and the ratio YA of the tetracarboxylic anhydride or its derivative used satisfy the relationship 40 mol %≦XA+YA≦200 mol %.

11. The liquid crystal light control device according to claim 1 or 2, wherein the liquid crystal composition contains a dichroic dye.

12. The liquid crystal light control device according to claim 1 or 2, wherein the liquid crystal layer has a thickness of 1 to 75 μm.

13. The liquid crystal light control element according to claim 1 or 2, wherein d / p in the liquid crystal light control element is 1 to 8.

14. A liquid crystal alignment film used in the liquid crystal light control element according to claim 1 or 2.

15. A liquid crystal alignment agent for forming the liquid crystal alignment film according to claim 14.

16. The liquid crystal light control element described in claim 15, wherein the liquid crystal aligning agent contains a compound having at least one structure selected from an epoxy group, an isocyanate group, an oxetanyl group, an oxazoline group, a cyclocarbonate group, a hydroxy group, a hydroxyalkyl group, a lower alkoxyalkyl group, and a polymerizable unsaturated group.

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