Polymer, resin composition, liquid crystal aligning agent, resin coating film, and liquid crystal alignment film

Abstract

Provided are a resin composition and a liquid crystal aligning agent having high rework characteristics of resin coating films and liquid crystal alignment films. Also provided are: a liquid crystal aligning agent that makes it possible to obtain a liquid crystal alignment film in which liquid crystal alignment is highly stable and uneven alignment of liquid crystals does not occur; the liquid crystal alignment film; and a liquid crystal display element using the liquid crystal alignment film.　At least one polymer selected from polyimide precursors and polyimides having a structure represented by formula [1]. (R1 represents a thermal leaving group. R2 represents a hydrogen atom or a monovalent organic group. * represents a bond.)

Description

Polymer, resin composition, liquid crystal alignment agent, resin coating, and liquid crystal alignment film

[0001] The present invention relates to a resin composition used for forming a resin film, a liquid crystal aligning agent used in the production of a liquid crystal display element, a liquid crystal alignment film obtained from the liquid crystal aligning agent, and a liquid crystal display element using the liquid crystal alignment film.

[0002] Resin coatings made of organic materials such as polymeric materials are widely used as interlayer insulating films and protective films in electronic devices due to their ease of formation and insulating properties. In particular, in liquid crystal display elements, which are well known as display devices, resin coatings made of organic materials are used as liquid crystal alignment films.

[0003] Currently, polyimide-based organic films, which have excellent durability, are used as resin coatings in industrial applications. In particular, these polyimide-based organic films are also used as liquid crystal alignment films in liquid crystal display elements. Polyimide-based organic films are formed from resin compositions containing polyamic acid and polyimide, which are polyimide precursors. Specifically, polyimide-based organic films are formed by applying a resin composition containing polyamic acid or polyimide to a substrate and then subjecting it to a baking process (see, for example, Patent Document 1).

[0004] The most widely used liquid crystal alignment film in industry is a process for regulating the alignment of liquid crystals (also called alignment treatment), in which the surface of a resin coating made of polyamic acid or polyimide formed on an electrode substrate is rubbed in one direction with a cloth such as cotton or nylon (also called rubbing treatment).

[0005] In recent years, with the increase in size and resolution of liquid crystal display elements, problems have become apparent, such as scratches and dust generation on liquid crystal alignment films caused by rubbing treatment, and low in-plane uniformity of liquid crystal alignment. In response to these problems, a new alignment treatment method has begun to be adopted, in which the alignment of liquid crystals is controlled by irradiating polarized radiation (light) (also known as photoalignment treatment). As this photoalignment treatment, methods utilizing photoisomerization reaction, photocrosslinking reaction, and photodecomposition reaction have been proposed (see, for example, Patent Document 2 and Patent Document 3).

[0006] Japanese Unexamined Patent Publication No. 9-278724 Japanese Unexamined Patent Application No. 9-297313 Japanese Unexamined Patent Application No. 2004-206091

[0007] Economic efficiency during the manufacture of electronic devices such as liquid crystal display elements and organic EL elements is important. Therefore, there is a demand for recycling defective substrates generated during the manufacture of electronic devices. Specifically, when defects such as foreign matter or uneven coating occur in a resin coating or liquid crystal alignment film, or when defects in the alignment of liquid crystals occur, it is necessary to remove the resin coating or liquid crystal alignment film from the substrate using an organic solvent or the like, and recover and reuse the substrate (also known as rework). However, polyimide-based organic films have high resistance to organic solvents, making it difficult to rework the resin coating or liquid crystal alignment film.

[0008] Liquid crystal alignment films used in liquid crystal display elements using the IPS (In Plane Switching) driving method or the FFS (Fringe Field Switching) driving method are required to have high liquid crystal alignment control properties (also called liquid crystal alignment stability) in order to suppress image retention (also called AC image retention) that occurs due to long-term alternating current driving. Furthermore, as mentioned above, these driving methods use photo-alignment treatment for alignment, but photo-alignment treatment is prone to variations in the amount of light irradiated within the liquid crystal alignment film (irradiation amount unevenness). This makes it easy for liquid crystal alignment unevenness to occur, resulting in problems such as display unevenness in the liquid crystal display element.

[0009] Therefore, an object of the present invention is to provide a resin composition and a liquid crystal alignment agent using a polyimide polymer having a specific structure, which have excellent reworkability for resin coatings and liquid crystal alignment films. Another object of the present invention is to provide a liquid crystal alignment film using the liquid crystal alignment agent, which has high liquid crystal alignment stability and does not cause uneven alignment of the liquid crystal. Another object of the present invention is to provide a liquid crystal display element equipped with a liquid crystal alignment film that meets the above requirements. Another object of the present invention is to provide a diamine having a specific structure.

[0010] As a result of intensive research into achieving the above object, the present inventors have completed the present invention, which has the following gist: A polyimide precursor having a structure of the following formula [1] and at least one polymer selected from polyimides: (R １ represents a thermally detachable group. ２ represents a hydrogen atom or a monovalent organic group. * represents a bond.

[0011] According to the present invention, resin coatings and liquid crystal alignment films with excellent reworkability for defective substrates can be obtained. This allows for the reuse of substrates, improving the economic efficiency of manufacturing electronic devices such as liquid crystal display elements. Furthermore, it is possible to provide liquid crystal display elements that are less susceptible to AC image retention and display unevenness. Therefore, the elements of the present invention are used as liquid crystal display elements for smartphones, tablet terminals, and the like. The mechanism by which the present invention provides liquid crystal display elements with the above-described excellent properties is not entirely clear, but is presumed to be roughly as follows.

[0012] -NH-R bonded to the benzene ring of the formula [1] １ R １ It is believed that the R group is eliminated by heat during the baking process when preparing the resin coating or liquid crystal alignment film, and the active amino group generated therein promotes the decomposition of the polyimide polymer. This increases the solubility of the resin coating or liquid crystal alignment film in organic solvents, improving the reworkability. In addition, the active amino group R １ Since the polymer is protected by the group, it does not decompose in the resin composition or the liquid crystal aligning agent, and becomes a solution with high storage stability.

[0013] In addition, —NH—C(═O)—N(R ２ The secondary amine (-NH-) at the R- site forms a hydrogen bond with the carbonyl group (-C(=O)-) at the same site and with the carbonyl group or amine in the specific polymer, resulting in interaction between the main chains of the specific polymer. This increases the stability of the liquid crystal alignment in the liquid crystal alignment film even with respect to alignment treatments such as rubbing treatment and photo-alignment treatment, making it less likely that display defects will occur due to AC image retention or uneven alignment of the liquid crystal in the liquid crystal display element. Furthermore, １Since the liquid crystal alignment agent has a highly hydrophobic structure, a large amount of the specific polymer can be present at the interface of the film in a solution state immediately after application of the liquid crystal alignment agent, and the specific polymer is present at the interface of the liquid crystal alignment film that contacts the liquid crystal, thereby enhancing these effects.

[0014] <Specific Structure> The specific structure is the structure of the formula [1]. １ and R ２ are as defined above, but among them, the following are preferred: １ is preferably a benzyloxycarbonyl group, a 9-fluorenylmethyloxycarbonyl group, an allyloxycarbonyl group, or a tert-butoxycarbonyl group (also referred to as a Boc group). A Boc group is more preferred because it is highly efficient in thermal elimination, elimination occurs at relatively low temperatures, and furthermore, the components generated upon elimination are discharged as harmless gases. ２ is preferably a hydrogen atom, a thermally detachable group, or an alkyl group having 1 to 3 carbon atoms. A hydrogen atom or a thermally detachable group is more preferred. A hydrogen atom or a Boc group is particularly preferred.

[0015] <Specific Polymer> The specific polymer is a polyimide precursor or polyimide (collectively referred to as a polyimide polymer) having a specific structure. It is preferably obtained by reacting a diamine component with a tetracarboxylic acid component. The polyimide precursor is a polyamic acid or polyamic acid ester having a structure of the following formula [A]: (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. ３ and A ４represents 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.) Polyimide has a structure of the following formula [A-4] and can be obtained by ring-closing (also called imidization) a polyamic acid of a polyimide precursor. In this case, if the ring-closure rate (also called imidization rate) of the amic acid group is less than 100%, the polyimide contains at least one structure of the following formulas [A-1] to [A-3] in addition to the structure of formula [A-4]. (R ａ and R ｂ has the same meaning as defined in the formula [A].) The diamine component is a diamine having two primary or secondary amino groups in the molecule, and examples of the tetracarboxylic acid component include 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.

[0016] The polyimide polymer is preferably a polyamic acid having a structural formula of a repeating unit 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. (R ａ and R ｂ has the same meaning as defined in the above formula [A]. (R ａ and R ｂ is the same as defined in the formula [A].) In addition, by a conventional synthesis method, A of the formula [A] can be added to the polymer of the formula [D]. １ and A ２ and 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.

[0017] The method for introducing a specific structure into a polyimide polymer preferably uses a diamine having a specific structure as part of the raw material, and in particular, it is preferable to use a diamine of the following formula [1a] (also referred to as a specific diamine): R１ and R ２ The details and preferences of X are the same as those of the formula [1]. １ is a single bond or ２ It represents a 2-valent organic group. ２ ) ａ - (where a is an integer of 1 to 3) is preferred. ２ R represents a divalent organic group. Among them, a divalent organic group having a benzene ring, a cyclohexane ring, or a nitrogen-containing heterocycle is preferred. A benzene ring is more preferred. ３ and R ４ are each independently a hydrogen atom or a monovalent organic group. Of these, they are preferably each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferably, they are each independently a hydrogen atom.

[0018] Specific specific diamines include those represented by the following formulas [1a-1] to [1a-30]. (A ２ each represents a hydrogen atom or a Boc group.

[0019] (A ３ each represents a hydrogen atom or a Boc group.

[0020] (A ４ Each m1 independently represents an integer of 1 to 6.

[0021] (A ５ Each m2 independently represents an integer of 1 to 6.

[0022] (A ６ Each of m3 independently represents an integer of 1 to 6.

[0023] (A ７ Each of m4 independently represents an integer of 1 to 6.

[0024] (A８ each independently represents a hydrogen atom or a Boc group; each m5 independently represents an integer of 1 to 6.

[0025] (A ９ each independently represents a hydrogen atom or a Boc group.

[0026] (A １０ each independently represents a hydrogen atom or a Boc group.

[0027] (A １１ each independently represents a hydrogen atom or a Boc group.

[0028] Among these, formulas [1a-1] to [1a-4] or formulas [1a-9] to [1a-16] are preferred. Formulas [1a-1] to [1a-4] are more preferred. The proportion of the specific diamine used is 1 to 80 mol% based on the total diamine component, from the viewpoint of the rework properties of the resin coating film and the liquid crystal alignment film. More preferred is 1 to 60 mol%. Particularly preferred is 1 to 50 mol%. Furthermore, the specific diamine can be used alone or in combination of two or more types depending on the respective properties.

[0029] The polyimide polymer may contain diamines other than the specific diamines as diamine components, as long as the effects of the present invention are not impaired. Specific examples include the "other diamines" described on pages 8 to 15 (paragraphs

[0020] to

[0026] ) of International Publication WO 2023 / 074568 (published May 4, 2023). These other diamines may be used alone or in combination of two or more depending on the properties of the polymer.

[0030] As the tetracarboxylic acid component for producing the polyimide polymer, it is preferable to use a tetracarboxylic acid dianhydride represented by the following formula [2], or a tetracarboxylic acid derivative thereof, such as a tetracarboxylic acid, a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl ester, or a tetracarboxylic acid dialkyl ester dihalide (collectively referred to as a specific tetracarboxylic acid component). Z represents at least one structure selected from the following formulas [2a] to [2l]. (Z Ａ ~Z Ｄ each independently represents a hydrogen atom, a methyl group, a chlorine atom or a benzene ring. Ｅ and Z Ｆ each independently represents a hydrogen atom or a methyl group.

[0031] Among these, from the viewpoints of ease of synthesis and ease of polymerization reactivity when producing a polymer, Z is preferably formula [2a], formula [2c], formula [2d], formula [2e], formula [2f], formula [2g], formula [2k], or formula [2l]. Formula [2a], formula [2e], formula [2f], formula [2g], formula [2k], or formula [2l] is more preferred. Formula [2a], formula [2e], formula [2f], formula [2g], or formula [2l] is particularly preferred. The proportion of the specific tetracarboxylic acid component used is preferably 1 mol % or more, based on the total tetracarboxylic acid components. More preferably, it is 5 mol % or more. Particularly preferably, it is 10 mol % or more. From the viewpoint of the optical properties of a liquid crystal display element, the most preferred proportion of the specific tetracarboxylic acid component used is 10 to 100 mol % based on the total tetracarboxylic acid components.

[0032] Furthermore, a specific polymer may be prepared by using a tetracarboxylic acid component having a specific structure. In this case, the tetracarboxylic acid component may be any of the following formulas [2a-1] to [2a-6]. (B １ each represents a hydrogen atom or a Boc group. (B ２ each independently represents a hydrogen atom or a Boc group.

[0033] The polyimide polymer may contain tetracarboxylic acid components other than the specific tetracarboxylic acid component and the tetracarboxylic acid component having the specific structure, as long as the effects of the present invention are not impaired. Examples of other tetracarboxylic acid components include the tetracarboxylic acid compounds, tetracarboxylic acid dianhydrides, dicarboxylic acid dihalide compounds, dicarboxylic acid dialkyl ester compounds, and dialkyl ester dihalide compounds shown below. Specific examples include the "other tetracarboxylic acid components" described on pages 34 to 35 (paragraph

[0057] ) of International Publication WO 2015 / 012368 (published January 29, 2015). The specific tetracarboxylic acid component and other tetracarboxylic acid components may be used singly or in combination, depending on their respective properties.

[0034] The method for synthesizing a polyimide polymer is not particularly limited. It is typically obtained by reacting a diamine component with a tetracarboxylic acid component. Specific examples include the method described on pages 35-36 of International Publication WO2015 / 012368 (published January 29, 2015). 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.

[0035] The reaction between the diamine component and the tetracarboxylic acid component is usually carried out in a solvent containing the diamine component and the tetracarboxylic acid component. The solvent used is not particularly limited as long as it dissolves the resulting 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 formulas [D1] to [D3] can be used. (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.) 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 solvent to the extent that it does not precipitate. Furthermore, since moisture in the solvent inhibits the polymerization reaction and may even cause hydrolysis of the polyimide precursor, it is preferable to use a solvent that has been dehydrated and dried.

[0036] 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 taken as 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. In the present invention, the total number of moles of the tetracarboxylic acid components may be less than 1.0, i.e., the total number of moles of the tetracarboxylic acid components may be smaller than the number of moles of the diamine components. In this case, specifically, when the total number of moles of the diamine components is taken as 1.0, the total number of moles of the tetracarboxylic acid components is preferably 0.80 or more and less than 1.00.

[0037] Polyimides are obtained by ring-closing a polyimide precursor, and the imidization rate does not necessarily have to be 100% and can be adjusted as desired depending on the application and purpose. From the viewpoint of solubility in solvents, an imidization rate of 40 to 90% is preferred, and 50 to 80% is more preferred.

[0038] The polyimide polymer may be converted into a terminal-capped polymer using a terminal-capping agent. Terminal-capped polymers have the effect of increasing the film hardness of resin coatings and liquid crystal alignment films, and improving the adhesion between the liquid crystal alignment film and the sealant in liquid crystal display elements. The method for obtaining the terminal-capped polymer is not particularly limited. Specific examples include the method described on pages 24 and 25 of International Publication WO2023 / 074568 (published May 4, 2023). From the viewpoints of the strength of the resin coatings and liquid crystal alignment films obtained therefrom, workability during film formation, and coatability, the molecular weight of the polyimide polymer is preferably 5,000 to 1,000,000 in terms of Mw (weight average molecular weight) measured by Gel Permeation Chromatography (GPC). A molecular weight of 10,000 to 150,000 is more preferred.

[0039] <Resin Composition and Liquid Crystal Alignment Agent> The resin composition and liquid crystal alignment agent (collectively referred to as a cured film composition) are solutions for forming a resin film and a liquid crystal alignment film (collectively referred to as a cured film), and are solutions 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 need to be specific polymers, and polyimide-based polymers without a specific structure may be mixed. In this case, the proportion of the polyimide-based polymer without a specific structure used is preferably 10 to 1,000 parts by mass, more preferably 10 to 400 parts by mass, per 100 parts by mass of the specific polymer. Furthermore, polymers other than polyimide-based polymers may be mixed with the polymer components. Specific examples include cellulose-based polymers, acrylic polymers, methacrylic polymers, polystyrene, polyamides, and polysiloxanes.

[0040] The content of the solvent in the cured film composition can be appropriately selected from the viewpoints of the application method and obtaining the desired cured film thickness. In particular, from the viewpoint of forming a uniform cured film by application, the content of the solvent in the cured film composition is preferably 50 to 99.9 mass %, more preferably 60 to 99 mass %, and particularly preferably 65 to 99 mass %. The solvent used in the cured film composition is not particularly limited as long as it is a solvent that dissolves the specific polymer. Of these, the following solvents (also referred to as solvent type A) are preferably used. Examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, and 4-hydroxy-4-methyl-2-pentanone. Among these, it is preferable to use N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone. These may be used alone or in combination. When the specific polymer has high solubility in the solvent, the following solvents (also referred to as Solvent Type B) can be used. For example, Solvent Type B described on pages 58 to 60 of International Publication WO2014 / 171493 (published October 23, 2014) can be mentioned. Among these, it is preferable to use 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, dipropylene glycol dimethyl ether, cyclohexanone, cyclopentanone, or the solvents represented by the formulae [D1] to [D3]. Furthermore, when using the solvent B type, it is preferable to use it in combination with N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone of the solvent A type for the purpose of improving the coatability of the cured film composition. The solvent B type can improve the coatability and surface smoothness of the cured film, so it is preferable to use it in combination with the solvent A type. In this case, the solvent B type is preferably used in an amount of 1 to 60 mass% of the total solvent contained in the cured film composition. Of these, 10 to 50 mass% is preferable. 20 to 40 mass% is more preferable.

[0041] In order to increase the film strength of the cured film, it is preferable to incorporate a compound (collectively referred to as a crosslinkable compound) having at least one selected from an epoxy group, an isocyanate group, an oxetane group, a cyclocarbonate group, a hydroxy group, a hydroxyalkyl group, and a lower alkoxyalkyl group. In this case, the compound must contain two or more of these groups. Specific examples of crosslinkable compounds having an epoxy group or an isocyanate group include the crosslinkable compounds having an epoxy group or an isocyanate group described on pages 63-64 of International Publication WO2014 / 171493 (published October 23, 2014). Specific examples of crosslinkable compounds having an oxetane group include the crosslinkable compounds of formulas [4a] to [4k] described on pages 58-59 of International Publication WO2011 / 132751 (published October 27, 2011). Specific examples of crosslinkable compounds having a cyclocarbonate group include the crosslinkable compounds of formula [5-1] to formula [5-42] listed on pages 76 to 82 of International Publication WO2012 / 014898 (published February 2, 2012). Specific examples of crosslinkable compounds having a hydroxyl group, a hydroxyalkyl group, and a lower alkoxyalkyl group include the melamine derivatives or benzoguanamine derivatives listed on pages 65 to 66 of International Publication WO2014 / 171493 (published October 23, 2014), and the crosslinkable compounds of formula [6-1] to formula [6-48] listed on pages 62 to 66 of International Publication WO2011 / 132751 (published October 27, 2011). The proportion of the crosslinkable compound used in the cured film composition is preferably 0.1 to 100 parts by mass per 100 parts by mass of all polymer components. From the viewpoint of promoting the crosslinking reaction and achieving the desired effect, the amount is more preferably 0.1 to 50 parts by mass, and particularly preferably 1 to 30 parts by mass.

[0042] The cured film composition may contain compounds that improve the uniformity of the cured film thickness and surface smoothness, as well as compounds that improve the adhesion between the cured film and the substrate, as long as the effects of the present invention are not impaired. Examples of compounds that improve the uniformity of the cured film thickness and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. Specific examples include the surfactants described on page 67 of International Publication WO 2014 / 171493 (published October 23, 2014). The amount of surfactant used is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, based on 100 parts by mass of all polymer components. Specific examples of compounds that improve the adhesion between the cured film and the substrate include the compounds described on pages 67 to 69 of International Publication WO 2014 / 171493 (published October 23, 2014). The amount of surfactant used is preferably 0.1 to 30 parts by mass, based on 100 parts by mass of all polymer components. More preferably, the amount is 1 to 20 parts by mass.

[0043] In addition to the compounds other than those mentioned above, the cured film composition may contain a dielectric or conductive substance for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the cured film.

[0044] <Resin Coating> The resin composition can be applied to a substrate, baked, and then used as a resin coating. The substrate used to form the resin coating can be a glass substrate, a silicon wafer, or a plastic substrate such as an acrylic substrate or a polycarbonate substrate, depending on the intended electronic device. The method for applying the resin composition is not particularly limited; industrially, methods such as dipping, roll coating, slit coating, spinner coating, spray coating, screen printing, offset printing, flexographic printing, or inkjet coating are used. These application methods are used depending on the intended purpose. After applying the resin composition to the substrate, the solvent can be evaporated at a temperature of 30 to 300°C, preferably 30 to 250°C, depending on the solvent used in the resin composition, using a heating means such as a hot plate, a hot air circulation oven, or an IR (infrared) oven, to form a resin coating. The thickness of the resin coating after heating can be adjusted to 0.01 to 100 μm depending on the intended purpose.

[0045] <Liquid Crystal Alignment Film / Liquid Crystal Display Element> A liquid crystal alignment agent can be applied to a substrate, baked, and then subjected to alignment treatment such as rubbing or photo-alignment treatment to form a liquid crystal alignment film. The substrate used for 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 and polycarbonate substrates can also be used. From the perspective of simplifying the manufacturing process, it is preferable to use a substrate formed with an ITO (Indium Tin Oxide) electrode for liquid crystal drive. Furthermore, in reflective liquid crystal display elements, an opaque substrate such as a silicon wafer can be used for only one substrate. In this case, light-reflecting materials such as aluminum can also be used for the electrodes. The application method for the liquid crystal alignment agent is not particularly limited, but industrially, screen printing, offset printing, flexographic printing, inkjet printing, etc. are commonly used. Other application methods include dipping, roll coating, slit coating, spinning, and spraying, and these may be used depending on the purpose. After applying the liquid crystal alignment 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 alignment agent, to form a liquid crystal alignment film. In particular, when a plastic substrate is used as the substrate, treatment at a temperature of 30 to 150°C is preferred. The thickness of the liquid crystal alignment film after baking is preferably 5 to 500 nm, because if it is too thick, it will be disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the element may decrease. Therefore, the thickness is preferably 5 to 500 nm, more preferably 10 to 300 nm, and particularly preferably 10 to 250 nm.

[0046] When tilting or horizontally aligning liquid crystals, as in the case of liquid crystal display elements using the TN (Twisted Nematic) drive system, the IPS drive system, or the FFS drive system, the baked liquid crystal alignment film is subjected to an alignment treatment such as a rubbing treatment in which the liquid crystal alignment film is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, or a photo-alignment treatment. In contrast, in the case of the VA (Vertical Alignment) drive system, the alignment treatment is not required. The photo-alignment treatment is a method in which the surface of the liquid crystal alignment film is irradiated with polarized radiation in a certain direction, and optionally, a heat treatment is performed at a temperature of 150 to 250°C. The radiation can be ultraviolet light or visible light having a wavelength of 100 to 800 nm. Of these, ultraviolet light having a wavelength of 100 to 400 nm is preferred. Ultraviolet light having a wavelength of 200 to 400 nm is more preferred. The radiation dose is 1 to 10,000 mJ / cm. ２ Among these, 100 to 5,000 mJ / cm is preferable. ２ is preferred. When irradiating with radiation, it is preferable to irradiate the substrate with the liquid crystal alignment film while heating it at 50 to 250°C in order to increase the stability of the liquid crystal alignment. This allows the liquid crystals to be stably aligned in a specific direction. The liquid crystal alignment film treated by the above method can be subjected to a contact treatment or heat treatment using water or an organic solvent. The organic solvent used in the contact treatment is not particularly limited as long as it dissolves decomposition products generated from the liquid crystal alignment film by irradiation with radiation. Specific examples include methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. These organic solvents and water can be used alone or in combination. The heat treatment temperature is preferably 50 to 300°C. A temperature of 120 to 250°C is more preferred. The heat treatment time is preferably 1 to 30 minutes.

[0047] The liquid crystal used in the liquid crystal display element can be nematic, smectic, or cholesteric liquid crystal. From the viewpoint of low-voltage operation, a liquid crystal with a large dielectric constant anisotropy and a large refractive index anisotropy is preferred. Furthermore, two or more types of liquid crystal can be mixed and used depending on the physical properties of the phase transition temperature, dielectric constant anisotropy, and refractive index anisotropy. Spacers can also be incorporated into the liquid crystal to control the electrode gap (also called the gap) of the liquid crystal display element. The method for injecting the liquid crystal is not particularly limited, but examples include the following. Specifically, when glass substrates are used as the substrates, a pair of substrates each having a liquid crystal alignment film formed thereon is prepared, and a sealant is applied to the four sides of one substrate, excluding a portion. Then, the other substrate is attached with the liquid crystal alignment film facing inward to produce an empty cell. A liquid crystal composition is then injected under reduced pressure from the area not coated with the sealant to obtain a liquid crystal composition-injected cell. Furthermore, when plastic substrates or films are used as the substrates, a method can be used in which a pair of substrates on which a liquid crystal alignment film has been formed is prepared, a liquid crystal composition is dropped onto one of the substrates by an ODF (One Drop Filling) method, an inkjet method, or the like, and then the other substrate is bonded to obtain a liquid crystal composition injection cell. The gap of the liquid crystal display element can be controlled using the spacers described above. As described above, this method can include introducing spacers of a desired size into the liquid crystal or using a substrate having column spacers of a desired size. Furthermore, when plastic or film substrates are used as the substrates and the substrates are bonded by lamination, the gap can also be controlled without introducing spacers. The gap size of the liquid crystal display element is preferably 1 to 100 μm, more preferably 1 to 50 μm, and particularly preferably 2 to 30 μm. If the gap is too small, the contrast of the liquid crystal display element decreases, and if it is too large, the driving voltage of the liquid crystal display element increases.

[0048] The present invention will be described in more detail below with reference to examples, but is not limited to these. The abbreviations used in the examples and comparative examples and the methods for measuring each physical property are as follows. <Solvent> NMP: N-methyl-2-pyrrolidone BCS: ethylene glycol monobutyl ether <Tetracarboxylic acid dianhydride> CA-1: tetracarboxylic acid dianhydride of the following formula [CA-1] <Specific diamine> DA-1: Diamine of the following formula [DA-1] (Boc represents a tert-butoxycarbonyl group.) <Other diamines> DA-2: p-phenylenediamine DA-3 to DA-5: diamines of the following formulas [DA-3] to [DA-5] (Boc represents a tert-butoxycarbonyl group.) "Viscosity Measurement" Measurement was performed using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) at a temperature of 25°C, a sample volume of 1.1 mL, and a cone rotor TE-1 (1°34', R24). "Molecular Weight Measurement" The number average molecular weight (also referred to as Mn) and weight average molecular weight (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 Resonaq (formerly Showa Denko) K.K.) Column: GPC KD-803, KD-805 (manufactured by Resonaq (formerly Showa Denko) K.K.) in series Column temperature: 50°C Eluent: N,N'-dimethylformamide (containing lithium bromide monohydrate (LiBr.H) as an additive) ２ 0) at 30 mmol / L (liter), anhydrous crystals of phosphoric acid (o-phosphoric acid) at 30 mmol / L, tetrahydrofuran (THF) at 10 ml / L) Flow rate: 1.0 mL / min Standard samples for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight: approximately 900,000, 150,000, 100,000, and 30,000) (manufactured by Tosoh Corporation), and polyethylene glycol (molecular weight: approximately 12,000, 4,000, and 1,000) (manufactured by Polymer Laboratory Co., Ltd.) "Synthesis of specific diamine (DA-1)" Compound (1-1) and specific diamine (DA-1) were prepared by １Identification was performed by H-NMR analysis. Apparatus: Fourier transform superconducting nuclear magnetic resonance spectrometer (FT-NMR) "AVANCE III" (manufactured by BRUKER) 500 MHz. Solvent: deuterated dimethyl sulfoxide (DMSO-d ６ , standard substance: tetramethylsilane)

[0049] Example 1 Under a nitrogen atmosphere, tert-butyl(2-amino-5-nitrophenyl)carbamate (25.3 g, 100 mmol), 4-nitrophenyl isocyanate (16.4 g, 100 mmol), and tetrahydrofuran (253 g) were added to a 500 mL four-neck flask and stirred at room temperature for 24 hours. After the reaction, the precipitated solid was filtered off and washed with tetrahydrofuran (500 g) for 1 hour. After filtering again and washing the cake with methanol (250 g), the solid was collected and dried under reduced pressure to obtain compound (1-1) (17.3 g, 41.5 mmol, yield 41.5%, yellow solid). １ H-NMR (500MHz, DMSO-d ６ ): δ (ppm) = 10.10 (s, 1H), 9.01 (s, 1H), 8.71 (s, 1H), 8.23 ​​(d, 4H), 8.06 (d, 1H), 7.72 (d, 2H), 1.49 (s, 9H). Under a nitrogen atmosphere, compound (1-1) (17.1 g, 41.0 mmol), tetrahydrofuran (342 g), and carbon-supported palladium (5% Pd carbon powder (50% water content) K type, manufactured by N.E. Chemcat Corporation, 1.71 g) were placed in a 500 mL four-neck flask, and after replacing the atmosphere with hydrogen, the reaction was carried out at normal pressure and room temperature for 24 hours. After completion of the reaction, the carbon-supported palladium was removed by filtration, and the filtrate was concentrated. Isopropyl alcohol (100 g) was added to the obtained crude product, and the resulting crystals were filtered off and dried under reduced pressure to obtain specific diamine (DA-1) (13.1 g, 36.7 mmol, yield 89.5%, pale pink solid). １ H-NMR (500MHz, DMSO-d ６): δ (ppm) = 8.26 (s, 1H), 8.18 (s, 1H), 7.46 (s, 1H), 7.05-7.02 (m, 2H), 6.96 (d, 1H), 6 .79 (s, 1H), 6.50-6.47 (m, 2H), 6.26 (d, 1H), 4.93 (s, 2H), 4.73 (s, 2H), 1.44 (s, 9H).

[0050] "Synthesis of Polyimide Polymer" Example 2 DA-1 (1.07 g, 3.00 mmol), DA-2 (0.324 g, 3.00 mmol), and NMP (10.2 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at 25°C while supplying nitrogen. After cooling to 25°C, CA-1 (1.23 g, 5.50 mmol) and NMP (9.00 g) were added, and the mixture was stirred at 40°C for 24 hours to obtain a polyamic acid solution (PAA-1) (viscosity: 334 mPa s) with a solids concentration of 12% by mass. The Mn of this polyamic acid was 11,776, and the Mw was 26,301.

[0051] Example 3: DA-1 (0.643 g, 1.80 mmol), DA-2 (0.130 g, 1.20 mmol), DA-3 (0.440 g, 1.80 mmol), DA-4 (0.478 g, 1.20 mmol), and NMP (12.4 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at 25 ° C. while supplying nitrogen. Thereafter, CA-1 (1.25 g, 5.58 mmol) and NMP (9.20 g) were added, and the mixture was stirred at 40 ° C. for 24 hours to obtain a polyamic acid solution (PAA-2) (viscosity: 292 mPa s) with a solids concentration of 12% by mass. The Mn of this polyamic acid was 11,165, and the Mw was 27,779.

[0052] Comparative Example 1: DA-2 (0.151 g, 1.40 mmol), DA-3 (0.513 g, 2.10 mmol), DA-4 (0.558 g, 1.40 mmol), DA-5 (0.509 g, 2.10 mmol), and NMP (12.7 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was dissolved by stirring at 25°C while supplying nitrogen. Subsequently, CA-1 (1.48 g, 6.62 mmol) and NMP (10.9 g) were added, and the mixture was stirred at 40°C for 24 hours to obtain a polyamic acid solution (PAA-3) (viscosity: 956 mPa s) with a solids concentration of 12% by mass. The Mn of this polyamic acid was 17,509 and the Mw was 42,610. The synthesized polyimide-based polymer is shown in Table 1.

[0053]

[0054] "Preparation of Resin Compositions and Liquid Crystal Alignment Agents" In the following Examples 4, 5, and Comparative Example 2, examples of preparing resin compositions are described. These resin compositions are also used to evaluate liquid crystal alignment agents. The prepared resin compositions and liquid crystal alignment agents are shown in Table 2.

[0055]

[0056] "Evaluation of Rework Properties" The resin compositions obtained by the manufacturing methods of the Examples and Comparative Examples were filtered through a filter with a pore size of 1.0 μm and then spin-coated onto a glass substrate (30 mm wide x 40 mm long) with an ITO electrode. The resulting substrate was then dried on a hot plate at 80°C for 60 seconds and baked in an infrared heating furnace at 230°C for 20 minutes to obtain a substrate with a resin film having a thickness of 100 nm. The resulting resin-coated substrate was immersed in a rework agent (PK-SFR7500, manufactured by Parker Corporation) for 60 seconds, rinsed with running ultrapure water for 30 seconds, and dried with an air blower. Rework properties were evaluated based on the difference in film thickness (also referred to as the film retention rate) before and after treatment with the rework agent. Specifically, the film retention rate was calculated using the following formula, and a lower film retention rate was determined to indicate better rework properties. Remaining film rate (%) = (film thickness after treatment with rework agent / film thickness before treatment with rework agent) × 100. Since the resin compositions obtained by the manufacturing methods of the Examples and Comparative Examples can be used as liquid crystal alignment agents, the evaluation of the rework properties of the resin coating obtained from the resin composition was also used to evaluate the rework properties of the liquid crystal alignment film obtained from the liquid crystal alignment agent. The evaluation results of the rework properties are shown in Table 3.

[0057] "Evaluation of Liquid Crystal Alignment Stability" The liquid crystal alignment stability was evaluated using the liquid crystal alignment agents obtained by the manufacturing methods of the Examples and Comparative Examples. This evaluation was intended to evaluate the AC afterimage of a liquid crystal display element, which occurs when the stability of the liquid crystal alignment decreases due to long-term AC driving. First, a liquid crystal cell using the FFS driving method was fabricated. A rectangular glass substrate measuring 30 mm x 35 mm and 0.7 mm thick was used as the substrate. A solid-patterned ITO electrode constituting a common electrode was formed on the substrate as the first layer. A SiN (silicon nitride) film deposited by CVD (chemical vapor deposition) was formed on the first common electrode as the second layer. The second SiN film had a thickness of 300 nm, which was thick enough to function as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an ITO film was placed on the second SiN film as the third layer, forming two pixels, a first pixel and a second pixel, each measuring 10 mm long and 5 mm wide. This electrode-equipped substrate had a structure in which a first-layer common electrode and a third-layer pixel electrode were insulated by a second-layer SiN film. The third-layer pixel electrode had a comb-like shape, with a central bend at an interior angle of 160° and multiple 3 μm-wide electrode lines arranged parallel to each other at 6 μm intervals. Each pixel was formed by multiple electrode lines, with a first region and a second region separated by a line connecting the bent portions. Next, the liquid crystal alignment agent was filtered through a 1.0 μm pore size filter and then spin-coated onto the electrode-equipped substrate (hereinafter referred to as the electrode substrate) and a glass substrate (hereinafter referred to as the counter substrate) with a 4 μm-tall columnar spacer and an ITO electrode formed on its backside. The resulting coating was then dried on a hot plate at 80°C for 2 minutes and baked in an infrared oven at 230°C for 20 minutes to obtain an electrode substrate and a counter substrate with a 100 nm-thick liquid crystal alignment film. The liquid crystal alignment film surfaces of both substrates were irradiated with polarized ultraviolet light at 200 to 500 mJ / cm through a 254 nm bandpass filter and a polarizer. ２The substrate was then irradiated with light and further baked in an infrared heating furnace at 230°C for 30 minutes to obtain an electrode substrate and counter substrate with a liquid crystal alignment film that had been subjected to an alignment treatment. As a result, the liquid crystal alignment film on the electrode substrate was aligned so that the direction equally dividing the interior angles of the pixel bends was perpendicular to the alignment direction of the liquid crystal, and the liquid crystal alignment film on the counter substrate was aligned so that the alignment direction of the liquid crystal on the electrode substrate coincided with the alignment direction of the liquid crystal on the counter substrate when the liquid crystal cell was fabricated. The electrode substrate and counter substrate with a liquid crystal alignment film that had been subjected to the alignment treatment were combined, and a thermosetting sealant (XN-1500T, manufactured by Mitsui Chemicals, Inc.) was printed around the periphery of the liquid crystal alignment film surface of one substrate, leaving the liquid crystal injection port. The other substrate was then bonded to the other substrate, with the liquid crystal alignment film surface facing inward, so that the alignment directions of the respective liquid crystal alignment films were at 0°. After bonding, the bonded substrates were pressed together and heat-treated at 150°C for 60 minutes to harden the sealant and produce an empty cell. Liquid crystal (PA-1492, manufactured by DIC Corporation) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain a liquid crystal cell of the FFS driving system (hereinafter referred to as a liquid crystal cell). The obtained liquid crystal cell was heated at 120°C for 1 hour and then left overnight at 23°C to evaluate the stability of the liquid crystal alignment. This liquid crystal cell was then placed under a high-brightness backlight (light source: LED, brightness: 25,000 cd / m) with a surface temperature of 50°C. ２) and an AC voltage of ±4.3 V at a frequency of 30 Hz was applied for 144 hours. The pixel electrode and common electrode of the liquid crystal cell were then shorted and left at 23°C for one day. For the liquid crystal cell subjected to the above treatment, the deviation between the alignment direction of the liquid crystal in the first region of the pixel and the alignment direction of the liquid crystal in the second region of the pixel when no voltage was applied was calculated as an angle. Specifically, the liquid crystal cell was placed between two polarizing plates arranged so that their polarization axes were perpendicular to each other, and the backlight was inverted to adjust the alignment angle of the liquid crystal cell so that the transmitted light intensity in the first region of the first pixel was minimized. Next, the rotation angle Δ required to rotate the liquid crystal cell so that the transmitted light intensity in the second region of the first pixel was minimized was calculated. The first and second regions of the second pixel were similarly compared, and the same angle Δ was calculated. The average of the angles Δ for the first and second pixels was then calculated as the rotation angle Δ of the liquid crystal cell. The smaller the rotation angle Δ, the better the stability of the liquid crystal alignment, and the less likely AC image retention will occur in the liquid crystal display element. The results of the evaluation of the stability of the liquid crystal alignment are shown in Table 4.

[0058] "Evaluation of Liquid Crystal Alignment Irregularities" Using a liquid crystal cell (hereinafter referred to as the liquid crystal cell) with an FFS drive system prepared using the method described in "Evaluation of Liquid Crystal Alignment Stability" above, the in-plane uniformity of the twist angle was evaluated. This evaluation was intended to evaluate the display unevenness of a liquid crystal display element caused by the occurrence of liquid crystal alignment unevenness. The variation in the liquid crystal twist angle was evaluated using an AxoStep (manufactured by AXOMETRICS). Specifically, the liquid crystal cell was placed on a measurement stage, and the distribution of circular retardance within the pixel plane was measured with no voltage applied, and 3σ, which is three times the standard deviation σ, was calculated. The smaller the 3σ value, the better the in-plane uniformity of the twist angle. In other words, the smaller the 3σ value, the less liquid crystal alignment unevenness occurs, and the less likely the liquid crystal display element is to experience display unevenness. The results of the evaluation of liquid crystal alignment unevenness are shown in Table 4.

[0059] Example 4 NMP (7.00 g) and BCS (3.00 g) were added to the polyamic acid solution (PAA-1) (5.00 g) obtained by the synthesis method of Example 2, and the mixture was stirred at room temperature for 60 minutes to obtain a resin composition (1). This resin composition showed no abnormalities such as turbidity or the generation of precipitates, and it was confirmed to be a homogeneous solution. This resin composition was also used for evaluation as a liquid crystal alignment agent (1). Using the obtained resin composition (1) and liquid crystal alignment agent (1), "evaluation of rework characteristics" and "evaluation of liquid crystal alignment unevenness" were performed under the above-mentioned conditions.

[0060] Example 5 NMP (7.00 g) and BCS (3.00 g) were added to the polyamic acid solution (PAA-2) (5.00 g) obtained by the synthesis method of Example 3, and the mixture was stirred at room temperature for 60 minutes to obtain a resin composition (2). This resin composition showed no abnormalities such as turbidity or the generation of precipitates, and it was confirmed to be a homogeneous solution. This resin composition was also used for evaluation as a liquid crystal aligning agent (2). Using the obtained resin composition (2) and liquid crystal aligning agent (2), "evaluation of rework characteristics," "evaluation of liquid crystal alignment stability," and "evaluation of liquid crystal alignment unevenness" were performed under the above-mentioned conditions.

[0061] Comparative Example 2 NMP (7.00 g) and BCS (3.00 g) were added to the polyamic acid solution (PAA-3) (5.00 g) obtained by the synthesis method of Comparative Example 1, and the mixture was stirred at room temperature for 60 minutes to obtain a resin composition (3). This resin composition showed no abnormalities such as turbidity or the generation of precipitates, and it was confirmed to be a homogeneous solution. This resin composition was also used for evaluation as a liquid crystal aligning agent (3). Using the obtained resin composition (3) and liquid crystal aligning agent (3), the "evaluation of rework characteristics," "evaluation of liquid crystal alignment stability," and "evaluation of liquid crystal alignment unevenness" were performed under the above-mentioned conditions.

[0062]

[0063]

[0064] As can be seen from the "Evaluation of Rework Properties" results shown in Table 3, the resin coatings and liquid crystal alignment films obtained from the resin compositions and liquid crystal alignment agents of the Examples of the present invention have superior rework properties compared to the resin coatings and liquid crystal alignment films of the Comparative Examples. Specifically, this is a comparison between Examples and Comparative Examples, which differ only in the presence or absence of a specific structure in the polymer, i.e., a comparison between Example 5 and Comparative Example 2. Furthermore, as can be seen from the "Evaluation of Liquid Crystal Alignment Stability" and "Evaluation of Liquid Crystal Alignment Irregularities" results shown in Table 4, liquid crystal display elements using liquid crystal alignment films obtained from the liquid crystal alignment agents of the Examples of the present invention have higher liquid crystal alignment stability and are less likely to experience liquid crystal alignment irregularities compared to the liquid crystal display elements of the Comparative Examples. Specifically, this is a comparison between Examples and Comparative Examples, which differ only in the presence or absence of a specific structure in the polymer, i.e., a comparison between Example 5 and Comparative Example 2.

[0065] By using a resin composition containing a polyimide polymer having a specific structure and a liquid crystal alignment agent of the present invention, a resin coating or liquid crystal alignment film with excellent reworkability for defective substrates can be obtained. This enables the substrate to be reused, improving the economic efficiency of manufacturing electronic devices such as liquid crystal display elements. Furthermore, by using a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, a liquid crystal display element that is less susceptible to AC image retention and display unevenness can be obtained. Therefore, the liquid crystal display element of the present invention is useful as a liquid crystal display element for smartphones, tablet terminals, and the like.

[0066] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2023-207919 filed on December 8, 2023 are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. At least one polymer selected from a polyimide precursor and a polyimide having the structure of the following formula [1]: (R １ represents a thermally detachable group. ２ represents a hydrogen atom or a monovalent organic group. * represents a bond.) 2. The polymer according to claim 1, wherein the polyimide precursor or the polyimide is a polyimide precursor or a polyimide that uses a diamine having the structure of the formula [1] as part of a raw material.

3. The polymer according to claim 2, wherein the diamine is a diamine represented by the following formula [1a]: (R １ and R ２ is the same as defined in formula [1]. １ represents a single bond or a divalent organic group. ２ R represents a divalent organic group. ３ and R ４ each independently represents a hydrogen atom or a monovalent organic group.

4. The polymer according to claim 3, wherein the diamine is at least one selected from the following formulas [1a-1] to [1a-4]: (Boc represents a tert-butoxycarbonyl group. ２ each represents a hydrogen atom or a Boc group.

5. The polymer according to any one of claims 2 to 4, wherein the proportion of the diamine used is 1 to 80 mol % based on the total diamine components.

6. The polymer according to claim 1 or 2, wherein the polyimide precursor or the polyimide is a polyimide precursor or a polyimide using a tetracarboxylic acid represented by the following formula [2] as part of a raw material: (Z represents at least one structure selected from the following formulas [2a] to [2l].) (Z Ａ ~Z Ｄ each independently represents a hydrogen atom, a methyl group, a chlorine atom or a benzene ring. Ｅ and Z Ｆ each independently represents a hydrogen atom or a methyl group.

7. A resin composition comprising the polymer according to claim 1.

8. A resin coating obtained from the resin composition according to claim 7.

9. A liquid crystal aligning agent comprising the polymer according to claim 1.

10. A liquid crystal alignment film obtained by using the liquid crystal aligning agent according to claim 9.

11. A liquid crystal display device having the liquid crystal alignment film according to claim 10.

12. A diamine represented by the following formula [1a]: (R １ represents a thermally detachable group. ２ represents a hydrogen atom or a monovalent organic group. １ represents a single bond or a divalent organic group. ２ R represents a divalent organic group. ３ and R ４ each independently represents a hydrogen atom or a monovalent organic group.

13. The diamine according to claim 12, which is represented by any one of the following formulas [1a-1] to [1a-4]: (Boc represents a tert-butoxycarbonyl group. ２ each represents a hydrogen atom or a Boc group.

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