WO2018174091A1 - Polymer and liquid crystal alignment agent using same - Google Patents

Abstract

Provided is a polymer which is highly soluble in organic solvents so that various solvents can be selected therefor and from which a filmy substance having excellent characteristics as a liquid crystal alignment agent, etc. can be obtained. The polymer comprises a repeating unit of a polyamic acid ester, a repeating unit of a polyimide and a repeating unit of a polyamic acid and has a basic group in any of the repeating units. [In formulae: X1 to X3 independently represent a tetravalent organic group derived from a tetracarboxylic acid; Y1 to Y3 independently represent a divalent organic group derived from a diamine, provided that at least one of Y to Y3 has a basic group; and R1 represents an alkyl group having 1-5 carbon atoms.]

Description

Polymer and liquid crystal aligning agent using the same

The present invention relates to a novel polymer suitable for, for example, a liquid crystal aligning agent and a liquid crystal aligning agent using the same.

In a liquid crystal display element used for a liquid crystal television, a liquid crystal display, and the like, a liquid crystal alignment film for controlling the alignment state of liquid crystals is usually provided in the element.
Currently, at least one polymer selected from polyamic acid, polyamic acid ester, and polyimide is used for the liquid crystal alignment film that is most widely used industrially from the viewpoint of its high reliability, liquid crystal alignment, and the like. Yes.

The liquid crystal alignment film can be formed by applying a liquid crystal aligning agent in which a polymer as described above is dissolved in an organic solvent on a substrate and baking it.
However, there are few solvents that can sufficiently dissolve these polymers. Therefore, there exists a problem that a polymer precipitates when storing a liquid crystal aligning agent at low temperature. In addition, there is a problem in that the properties of the liquid crystal display element are adversely affected as a result of poor applicability to the substrate and inability to obtain a uniform liquid crystal alignment film.
In order to solve these problems, a liquid crystal aligning agent or the like having a high solubility in an organic solvent and excellent printability has been proposed (see Patent Document 1 and Patent Document 2).

WO 2008/062877 WO2014 / 034790

An object of the present invention is to provide a polymer in which various solvents can be selected because of its high solubility in organic solvents, and as a result, the obtained film-like product has excellent characteristics as a liquid crystal aligning agent. And

As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by a polymer having a repeating unit of polyamic acid ester and a repeating unit of polyimide. .
That is, the gist of the present invention is as follows.
(1) A polymer having a repeating unit of polyamic acid ester, a repeating unit of polyimide, and a repeating unit of polyamic acid, and having a basic group in any of the repeating units.
(2) The repeating unit of the polyamic acid ester is represented by the following formula (1), the repeating unit of the polyimide is represented by the following formula (2), and the repeating unit of the polyamic acid is represented by the following formula (3). The polymer according to (1) above.

(In the above formulas (1) to (3), X ₁ , X ₂ and X ₃ are each independently a tetravalent organic group derived from a tetracarboxylic acid component. Y ₁ , Y ₂ and Y ₃ Are each independently a divalent organic group derived from a diamine, and at least one of Y ₁ , Y ₂ , and Y ₃ has a basic group, and R ₁ is an alkyl group having 1 to 5 carbon atoms. .)

(3) The content of the repeating unit of the polyamic acid ester, the repeating unit of the polyimide, and the repeating unit of the polyamic acid has 10 to 90 mol%, 9 to 89 mol%, and 1 to 81 mol%, respectively. The polymer according to (1) or (2) above.
(4) The polymer according to any one of (1) to (3) above, wherein the basic group is a pyrrole ring, imidazole ring, pyrazole ring, pyridine ring, pyrimidine ring, piperidine ring or piperazine ring. .
(5) The above-mentioned (2) to (4), wherein Y ₁ , Y ₂ and Y ₃ having the basic group are 5 to 90 mol% with respect to all of Y ₁ , Y ₂ and Y ₃ The polymer according to any one of the above.
(6) Any one of the above (2) to (5), wherein Y ₁ , Y ₂ and Y ₃ having the basic group are at least one selected from the group consisting of structures represented by the following formulae: The polymer according to item.

(7) In any one of the above (2) to (6), X1 to X3 in the formulas (1) to (3) are at least one selected from the group consisting of structures represented by the following formulas: Polymer.

(Wherein R ₃ to R ₆ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or a fluorine atom) And a monovalent organic group having 1 to 6 carbon atoms or a phenyl group.)
(8) A liquid crystal aligning agent containing the polymer described in any one of (1) to (7) above.
(9) The liquid crystal aligning film obtained from the liquid crystal aligning agent as described in said (8).
(10) A liquid crystal display device comprising the liquid crystal alignment film according to (9).

According to the present invention, various solvents can be selected because of its high solubility, and as a result, a polymer capable of giving a polymer solution having high printability on a substrate or the like can be obtained. The polymer of the present invention is particularly preferably used for a liquid crystal alignment agent that gives a liquid crystal alignment film for controlling the alignment of liquid crystal because of its high solubility and printability of the resulting polymer solution on a substrate.

The polymer of the present invention has a repeating unit of polyamic acid ester, a repeating unit of polyimide, and a repeating unit of polyamic acid, and has a basic group in the repeating unit (hereinafter also referred to as a specific polymer). ).
The repeating unit of polyamic acid ester, the repeating unit of polyimide, and the repeating unit of polyamic acid contained in the specific polymer can be represented by the following formulas (1) to (3), respectively.

In the above formulas (1) to (3), X ₁ , X ₂ and X ₃ are tetravalent organic groups derived from a tetracarboxylic acid derivative, and Y ₁ , Y ₂ and Y ₃ are divalent derived from a diamine. Wherein at least one of Y ₁ , Y ₂ and Y ₃ has a basic group, and R ₁ is an alkyl group having 1 to 5 carbon atoms. X ₁ , X ₂ , X ₃ and Y ₁ , Y ₂ , Y _{3, and} two R ¹ may be the same or different.
According to this invention, various things can be provided about content of the repeating unit of the polyamic acid ester in the specific polymer, the repeating unit of the said polyimide, and the repeating unit of the said polyamic acid. Among them, since high solubility is obtained, the content of each of the repeating unit of polyamic acid ester, the repeating unit of polyimide, and the repeating unit of polyamic acid is 10 to 90 mol%, 9 to 89 mol%. The content is preferably 1 to 81 mol%, more preferably 40 to 90 mol%, 9 to 59 mol%, and 1 to 51 mol%, respectively.
Hereinafter, the polymer which forms a specific polymer, and those raw materials are explained in full detail.

<Tetracarboxylic acid component>
Examples of the tetracarboxylic acid component for obtaining the specific polymer include tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, and tetracarboxylic acid dialkyl ester dihalide. Then, these are also collectively referred to as a tetracarboxylic acid component. Among them, it is preferable to use tetracarboxylic dianhydride as a raw material for producing the specific polymer.

<Tetracarboxylic dianhydride>
Examples of the tetracarboxylic dianhydride include an aliphatic tetracarboxylic dianhydride, an alicyclic tetracarboxylic dianhydride, an aromatic tetracarboxylic dianhydride, and the like. Can do.

In the formula, the structure of X is not particularly limited, and these are the same as the definitions of X ₁ , X ₂ and X ₃ in the repeating units of the above formulas (1) to (3). Specific examples include, but are not limited to, the following formulas (X1-1) to (X1-46).

In the above formula, R ³ to R ²³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or a fluorine atom And a monovalent organic group having 1 to 6 carbon atoms or a phenyl group.
In the case of a liquid crystal aligning agent, R ³ to R ^{6 in} formula (X1-1) are preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group, from the viewpoint of liquid crystal alignment. preferable. In the formula (X1-1), the following formula (X1-11) or (X1-12) is preferable.

In addition, the said tetracarboxylic dianhydride can be used individually by 1 type or in combination of 2 or more types.

<Diamine component>
The diamine component for obtaining the specific polymer of the present invention is represented by the following formula [2].

In the above formula, A ₁ and A ₂ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. In the case of a liquid crystal aligning agent, A ₁ and A ₂ are preferably a hydrogen atom or a methyl group from the viewpoint of liquid crystal alignment. The structure of Y is the same as the definition of Y ₁ , Y ₂ and Y ₃ in the repeating units of the above formulas (1) to (3). Specific examples are as follows, but are not limited thereto.

In the above formula, n is an integer of 1 to 6, Me is a methyl group, and Boc represents a tert-butoxycarbonyl group.

<Diamine having basic group>
A diamine having a basic group is used for producing the specific polymer because the reaction at the time of producing the specific polymer of the present invention is easy to proceed. Specific examples of the basic group are preferably a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a piperidine ring, or a piperazine ring. The basic group may be contained in the main chain of the diamine or in the side chain.
The diamine having a basic group has the structure of Y-71, Y-73, Y-96, Y-76, Y-77, Y-163, Y-164, Y-165 or Y-172 exemplified above. The diamine to contain is preferable. These diamine-derived structures may be contained in any of the repeating units in the above formulas (1) to (3), and may be contained in a plurality of repeating units.
The preferred content of the diamine having a basic group is preferably from 5 to 90 mol%, more preferably from 10 to 70 mol%, based on the total diamine component used in the production of the specific polymer of the present invention.

<Method for producing polyamic acid>
The polyamic acid used for the production of the specific polymer can be produced by the following method.
Specifically, tetracarboxylic dianhydride and diamine are reacted in the presence of an organic solvent at −20 to 150 ° C., preferably 0 to 50 ° C., for 30 minutes to 24 hours, preferably 1 to 12 hours. Can be manufactured.
The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc. in view of the solubility of the monomer and polymer. These may be used alone or in combination of two or more. May be used.

The concentration of the polymer is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation is difficult to occur and a high molecular weight product is easily obtained.
The polyamic acid obtained as described above can be recovered by precipitating a polymer by pouring it into a poor solvent while thoroughly stirring the reaction solution. Moreover, the powder of polyamic acid refine | purified by performing precipitation several times, washing | cleaning with a poor solvent, and normal temperature or heat-drying can be obtained. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene and the like, and water, methanol, ethanol, 2-propanol and the like are preferable.

<Production method of polyimide>
The polyimide used for the production of the specific polymer can be produced by imidizing the polyamic acid. A polyimide can also be produced by imidation of a polyamic acid ester.
When manufacturing a polyimide from a polyamic acid, chemical imidation which adds a catalyst to the solution of the said polyamic acid obtained by reaction with a diamine component and tetracarboxylic dianhydride is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer does not easily decrease during the imidization process.

Chemical imidization can be performed by stirring polyamic acid in an organic solvent in the presence of a basic catalyst and an acid anhydride. As an organic solvent, the solvent used at the time of the polymerization reaction mentioned above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like. Among them, use of acetic anhydride is preferable because purification after completion of the reaction is facilitated.

The temperature for carrying out the imidization reaction is −20 to 140 ° C., preferably 0 to 100 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times mol, preferably 2 to 20 times mol of the polyamic acid group, and the amount of acid anhydride is 1 to 50 times mol, preferably 3 to 30 times mol of the polyamic acid group. Is a mole. The imidation ratio of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.
Since the added catalyst and the like remain in the solution after the imidization reaction of the polyamic acid, the obtained imidized polymer is recovered by the means described below, and redissolved in an organic solvent. It is preferable to use a liquid crystal aligning agent.

The polyimide solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, and after washing with a poor solvent, an imidized polymer powder purified by drying at normal temperature or by heating can be obtained.
Examples of the poor solvent include, but are not limited to, methanol, 2-propanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and the like. Methanol, ethanol, 2-propanol, Acetone is preferred.

<Production of specific polymer via polyamic acid>
The specific polymer of the present invention is obtained by reacting an imidized polymer powder obtained by partially imidizing the polyamic acid obtained above or a polymer solution obtained by dissolving the imidized polymer in an organic solvent with an alcohol. Obtained by esterification.
Specifically, it is obtained by immersing the imidized polymer powder obtained above in alcohol or stirring it in alcohol. By immersing in alcohol for 15 to 100 hours, preferably 15 to 50 hours, a powder of a specific polymer can be obtained. The temperature during the reaction is preferably 20 to 60 ° C. When stirring in alcohol, the powder of the specific polymer can be obtained in 5 to 100 hours, preferably 20 to 70 hours.

When the polymer solution obtained by dissolving the imidized polymer powder obtained above in an organic solvent and an alcohol are added and reacted, the powder of the specific polymer can be obtained in 20 to 100 hours. Preferably it is 20 to 70 hours. The temperature during the reaction is preferably 20 to 60 ° C.
In the present invention, the polyamic acid repeating unit, the polyimide repeating unit, and the polyamic acid ester repeating unit can be adjusted by arbitrarily adjusting the imidation rate of the polyamic acid and by arbitrarily adjusting the esterification rate of the imidized product. A specific polymer contained in an arbitrary ratio can be obtained.

<Production of specific polymer via polyamic acid ester>
The specific polymer of the present invention can also be obtained by first producing a polyamic acid ester and imidizing it. The polyamic acid ester can be produced by the following methods (1) to (3).

(1) When manufacturing from polyamic acid Polyamic acid ester can be manufactured by esterifying the polyamic acid obtained from tetracarboxylic dianhydride and diamine. Specifically, it is produced by reacting a polyamic acid and an esterifying agent in the presence of an organic solvent at −20 to 150 ° C., preferably 0 to 50 ° C. for 30 minutes to 24 hours, preferably 1 to 4 hours. be able to. Depending on the reaction conditions, a polymer having a repeating unit of polyamic acid and polyamic acid ester can be produced at the same time, and a polymer having a repeating unit of polyamic acid, polyimide and polyamic acid ester can also be produced by imidization thereof.

The esterifying agent is preferably one that can be easily removed by purification, and N, N-dimethylformamide dimethyl acetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide Dineopentyl butyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p -Tolyltriazene, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride and the like. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents, and more preferably 2 to 4 molar equivalents, per 1 mol of the polyamic acid repeating unit.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc. from the solubility of the polymer, and these are used alone or in combination of two or more. May be. The concentration of the polymer in the organic solvent at the time of production is preferably 1 to 30% by mass, more preferably 5 to 20% by mass from the viewpoint that precipitation of the polymer hardly occurs and a high molecular weight product is easily obtained.

(2) When manufacturing by reaction of tetracarboxylic-acid diester dichloride and diamine Polyamic acid ester can be manufactured from tetracarboxylic-acid diester dichloride and diamine. Specifically, tetracarboxylic acid diester dichloride and diamine are reacted in the presence of a base and an organic solvent at −20 to 150 ° C., preferably 0 to 50 ° C. for 30 minutes to 24 hours, preferably 1 to 4 hours. Can be manufactured.
As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently. The addition amount of the base is preferably 2 to 4 times mol, preferably 2 to 3 times mol with respect to tetracarboxylic acid diester dichloride, from the viewpoint of easy removal and high molecular weight. More preferred.

The organic solvent used in the above reaction is preferably N-methyl-2-pyrrolidone, γ-butyrolactone or the like in view of the solubility of the monomer and polymer, and these may be used alone or in combination. The polymer concentration in the organic solvent at the time of production is preferably 1 to 30% by mass and more preferably 5 to 20% by mass from the viewpoint that the polymer is hardly precipitated and a high molecular weight product is easily obtained. In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the organic solvent used for the production of the polyamic acid ester is preferably dehydrated as much as possible, and the reaction is preferably performed in a nitrogen atmosphere to prevent contamination of the outside air. .

(3) When manufacturing from tetracarboxylic-acid diester and diamine Polyamic acid ester can be manufactured by polycondensing tetracarboxylic-acid diester and diamine. Specifically, tetracarboxylic diester and diamine are reacted in the presence of a condensing agent, a base, and an organic solvent at 0 to 150 ° C., preferably 0 to 100 ° C., for 30 minutes to 24 hours, preferably 3 to 15 hours. Can be manufactured.
Examples of the condensing agent include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazide. Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N , N ′, N′-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate diphenyl, and the like. The addition amount of the condensing agent is preferably 2 to 3 times by mole, more preferably 2 to 2.5 times by mole with respect to the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The addition amount of the base is preferably 2 to 4 moles, more preferably 2 to 3 moles, relative to the diamine component from the viewpoint of easy removal and high molecular weight.
Examples of the organic solvent include N-methyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylformamide and the like.
In the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably 0 to 1.0-fold mol, more preferably 2.0 to 3.0-fold mol based on the diamine component.

Among the methods for producing the three polyamic acid esters, since the high molecular weight polyamic acid ester is obtained, the production method of (1) or (2) is particularly preferable.
The polyamic acid ester solution obtained as described above can be polymerized by being poured into a poor solvent while being well stirred. Precipitation is performed several times, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained at room temperature or by heating and drying. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, toluene and the like, and water, methanol, ethanol, 2-propanol and the like are preferable.
When a specific polymer is produced by imidizing the polyamic acid ester thus obtained, a basic catalyst is added to the polyamic acid solution obtained by dissolving the polyamic acid ester solution or the polyamic acid ester resin powder in an organic solvent. Imidization is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is unlikely to decrease during the imidization process.

Chemical imidation can be performed by stirring the polyamic acid ester in the presence of a basic catalyst in an organic solvent. As an organic solvent, the solvent used at the time of the polymerization reaction mentioned above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, triethylamine is preferred because it has sufficient basicity to allow the reaction to proceed.
The temperature for carrying out the imidization reaction is −20 to 140 ° C., preferably 0 to 100 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times mol, preferably 2 to 20 times mol of the amic acid ester group. The imidation ratio of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.
A specific polymer can be obtained by imidating a polyamic acid ester as mentioned above and adjusting the imidation rate in that case.

<Liquid crystal aligning agent>
The specific polymer of the present invention can be used for various applications, but is preferably used as a liquid crystal aligning agent in view of its high solubility, excellent properties of the resulting film, and the like.
The liquid crystal aligning agent has a form of a solution in which a specific polymer is dissolved in an organic solvent. The molecular weight of the specific polymer is preferably 2,000 to 500,000 in terms of weight average molecular weight (Mw), more preferably 5,000 to 300,000, still more preferably 10,000 to 100,000. . The number average molecular weight (Mn) is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000. .

The concentration of the specific polymer in the liquid crystal aligning agent can be appropriately changed depending on the thickness of the coating film to be formed, but is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film. From the viewpoint of storage stability of the solution, it is preferably 10% by mass or less. A particularly preferred polymer concentration is 2 to 8% by mass.
The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as the polymer component is uniformly dissolved. Specific examples include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2 -Pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N, N-dimethylpropanamide and the like. You may use these 1 type or in mixture of 2 or more types. Moreover, even if it is a solvent which cannot melt | dissolve a polymer component uniformly by itself, if it is a range which a polymer does not precipitate, you may mix with said organic solvent.

The liquid crystal aligning agent may contain a solvent for improving the uniformity of the coating film when the liquid crystal aligning agent is applied to the substrate in addition to the organic solvent for dissolving the specific polymer component. Such a solvent is generally a solvent having a lower surface tension than that of the organic solvent and is a poor solvent having a low solubility. However, the specific polymer of the present invention has a high solubility in these solvents. Is also advantageously used. Specific examples thereof include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2- Propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, butyl cellosolve acetate, dipropylene Glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactate Amyl ester, and the like. Two or more of these solvents may be used in combination.

In addition to the above, the liquid crystal aligning agent includes a polymer other than the specific polymer, a dielectric or conductive material for changing electrical properties such as dielectric constant and conductivity of the liquid crystal aligning film, and adhesion between the liquid crystal aligning film and the substrate. Silane coupling agent for the purpose of improving the properties, crosslinkable compounds for the purpose of increasing the hardness and density of the liquid crystal alignment film, and the imidization of polyamic acid when the coating film is baked efficiently A target imidization accelerator may be added.

The liquid crystal alignment film is a film obtained by applying a liquid crystal aligning agent to a substrate, drying and baking. The substrate to which the liquid crystal aligning agent is applied is not particularly limited as long as it is a highly transparent substrate, and a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used together with a glass substrate or a silicon nitride substrate. At that time, it is preferable to use a substrate on which an ITO electrode or the like for driving the liquid crystal is used from the viewpoint of simplification of the process. In the reflective liquid crystal display element, an opaque material such as a silicon wafer can be used as long as it is only on one side of the substrate, and a material that reflects light such as aluminum can be used for the electrode in this case.
A method for applying the liquid crystal aligning agent is not particularly limited, but industrially, a method of performing screen printing, offset printing, flexographic printing, an inkjet method, or the like is common. Other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method, or a spray method, and these may be used depending on the purpose.

After the liquid crystal aligning agent is applied on the substrate, the solvent can be evaporated by a heating means such as a hot plate, a thermal circulation oven, or an IR (infrared) oven to form a liquid crystal alignment film. Arbitrary temperature and time can be selected for the drying and baking steps after applying the liquid crystal aligning agent of the present invention. Usually, a condition of baking at 50 to 120 ° C. for 1 to 10 minutes and then baking at 150 to 300 ° C. for 5 to 120 minutes is mentioned in order to sufficiently remove the contained solvent. If the thickness of the liquid crystal alignment film after baking is too thin, the reliability of the liquid crystal display element may be lowered, and thus it is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

The method for aligning the liquid crystal alignment film obtained from the liquid crystal aligning agent is not particularly limited. As the rubbing treatment method, an existing rubbing method or apparatus can be used. Examples of the material of the rubbing cloth include cotton, rayon, nylon, and polyester. For example, as disclosed in JP-A-55-143525, a liquid crystal alignment substrate in which an alignment film is applied on a transparent electrode substrate is used, and the rubbing cloth is attached to a roller on the alignment film surface. A method of obtaining uniform liquid crystal alignment by rubbing with a rubbing machine is widely used as a rubbing method.

In the case of the photo-alignment treatment method, the surface of the liquid crystal alignment film is irradiated with radiation deflected in a certain direction, and in some cases, preferably, heat treatment is performed at a temperature of 150 to 250 ° C. And a method of imparting a function). As the radiation, ultraviolet rays or visible rays having a wavelength of 100 to 800 nm can be used. Among these, ultraviolet rays having a wavelength of preferably 100 to 400 nm, more preferably 200 to 400 nm are preferable.
Further, in order to improve the liquid crystal alignment, the substrate coated with the liquid crystal alignment film may be irradiated with radiation while heating at 50 to 250 ° C. The radiation dose is preferably 1 to 10,000 mJ / cm ² . Of these, 100 to 5,000 mJ / cm ² is preferable. The liquid crystal alignment film thus prepared can stably align liquid crystal molecules in a certain direction.

A higher extinction ratio of polarized ultraviolet light is preferable because higher anisotropy can be imparted. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10: 1 or more, and more preferably 20: 1 or more. Further, the liquid crystal alignment film irradiated with polarized radiation can be subjected to contact treatment using water or a solvent by the above method.

The solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves a decomposition product generated from the liquid crystal alignment film by irradiation with radiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, 3- Examples thereof include methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate or cyclohexyl acetate. Of these, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate is preferable from the viewpoint of versatility and solvent safety. More preferred is water, 1-methoxy-2-propanol or ethyl lactate. The solvent may be used alone or in combination of two or more.

Examples of the above-described contact treatment, that is, treatment of water or a solvent on the liquid crystal alignment film irradiated with polarized radiation includes immersion treatment and spray treatment (also referred to as spray treatment). The treatment time in these treatments is preferably 10 seconds to 1 hour from the viewpoint of efficiently dissolving the decomposition products generated from the liquid crystal alignment film by radiation. In particular, the immersion treatment is preferably performed for 1 minute to 30 minutes. The solvent used in the contact treatment may be warmed at normal temperature, but is preferably 10 to 80 ° C. Of these, 20 to 50 ° C. is preferable. In addition, from the viewpoint of the solubility of the decomposition product, ultrasonic treatment or the like may be performed as necessary.

After the contact treatment, rinsing (also referred to as rinsing) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone, or baking of the liquid crystal alignment film is preferably performed. At that time, either one of rinsing and firing, or both may be performed. The firing temperature is preferably 150 to 300 ° C. Of these, 180 to 250 ° C. is preferable. More preferably, the temperature is 200 to 230 ° C. The firing time is preferably 10 seconds to 30 minutes. Among these, 1 to 10 minutes is preferable.
The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for liquid crystal display elements of various alignment methods such as a PSA method, an IPS method, and an FFS method. The liquid crystal display element is obtained using a liquid crystal cell by preparing a liquid crystal cell by a known method after obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention.

As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. Note that an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display may be used.
Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be ITO electrodes, for example, and are patterned so as to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a SiO ₂ —TiO ₂ film formed by a sol-gel method.

Next, a liquid crystal alignment film is formed on each substrate, the other substrate is overlaid on one substrate so that the liquid crystal alignment film faces each other, and the periphery is bonded with a sealant. In order to control the substrate gap, a spacer is usually mixed in the sealant, and it is preferable to spray a spacer for controlling the substrate gap on the in-plane portion where no sealant is provided. A part of the sealant is provided with an opening that can be filled with liquid crystal from the outside. Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealing agent through the opening provided in the sealing agent, and then the opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method utilizing capillary action in the atmosphere may be used. As the liquid crystal material, either a positive liquid crystal material or a negative liquid crystal material may be used. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates is attached to the surfaces of the two substrates opposite to the liquid crystal layer.
As described above, it is possible to obtain a liquid crystal alignment film that suppresses afterimages due to alternating current driving and has both adhesiveness with the sealant and the base substrate. In particular, it is useful for a liquid crystal alignment film obtained by irradiating polarized radiation.

Examples Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The following are the abbreviations of the compounds and the measurement methods of the respective properties.
<Tetracarboxylic dianhydride>
CBDA: 1,2,3,4, -cyclobutanetetracarboxylic dianhydride BODA: bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride

<Diamine>
3-AMPDA: 3,5-diamino-N- (pyridin-3-ylmethyl) benzamide p-PDA: paraphenylenediamine PCH7DAB: 1,3-diamino-4- [4- (trans-4-n-heptylcyclohexyl) Phenoxy] benzene <organic solvent>
MP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve

<Molecular weight measurement>
A normal temperature gel permeation chromatography (GPC) apparatus (GPC-101) manufactured by Showa Denko KK and a column manufactured by Shodex (KD-803, KD-805) were used. The measurement conditions are as follows.
Column temperature: 50 ° C.
Eluent: N, N′-dimethylformamide (additive: lithium bromide-hydrate (LiBr · H ₂ O) 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) 30 mmol / L, tetrahydrofuran (THF) is 10 ml / L), flow rate: 1.0 ml / min,
Standard samples for preparing calibration curves: TSK manufactured by Tosoh Corporation, standard polyethylene oxide (molecular weight: about 900,000, 150,000, 100,000, 30,000), and polyethylene glycol manufactured by Polymer Laboratories (molecular weight: about 12,000, 4) 1,000, 1,000).

<Measurement of imidization ratio>
Add 20 mg of polyimide powder to an NMR sample tube (Kusano Kagaku, NMR sampling tube standard φ5), and add 0.53 ml of deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) Then, it was completely dissolved by applying ultrasonic waves. With respect to this solution, proton NMR at 500 MHz was measured using an NMR measuring instrument (JNW-ECA500) manufactured by JEOL Datum. The imidation rate is determined by determining a proton derived from a structure that does not change before and after imidation as a reference proton, and a peak integrated value of this proton and a proton peak derived from the NH group of amic acid that appears in the vicinity of 9.0 to 11.0 ppm. It calculated | required by the following Numerical formula (1) using the integrated value.
Imidation ratio (%) = (1−α · x / y) × 100 (1)
In the above formula (1), x is the proton peak integrated value derived from the NH group of the amic acid, y is the peak integrated value of the reference proton, and α is the NH group of the amic acid in the case of polyamic acid (imidation rate is 0%). It is the number ratio of the reference proton to one proton.

<Measurement of imidization rate, esterification rate, amide rate of specific polymer>
The IR spectrum of the polyimide powder is measured by the KBR method. The absorption peak (benzene ring) height (a1) near 1500 cm ^{−1 and} the absorption peak (imide ring) height (b1) near 1380 cm ⁻¹ are measured, and b1 / a1 is calculated. Next, the IR spectrum of the specific polymer powder was measured by the KBR method, and the absorption peak (benzene ring) height (a2) near 1500 cm ⁻¹ and the absorption peak (imide ring) height (b2) near 1380 cm ^−1. And b2 / a2 is calculated.
The imidation ratio, esterification ratio, and amide ratio of the specific polymer were determined by the following mathematical formulas (1) to (3). In the following formula (1), β is the imidization ratio (%) of the polyimide powder.
Imidization rate (%) = ((b2 / a2) / (b1 / a1)) × β (1)
Esterification rate (%) = β − ((b2 / a2) / (b1 / a1) × β) (2)
Amide ratio (%) = 100-β (3)
In addition, the imidation ratio, esterification ratio, and amide ratio of the specific polymer indicate, in other words, the content of the polyimide repeating unit, the polyamic acid ester repeating unit, and the polyamic acid repeating unit in the specific polymer. Is.

<Example 1>
BODA (2.50 g, 10 mmol), PCH7DAB (3.81 g, 10 mmol), 3-AMPDA (4.85 g, 20 mmol), p-PDA (2.16 g, 20 mmol) were mixed in NMP (75.46 g). Then, CBDA (7.75 g, 39.5 mmol) and NMP (8.79 g) were added and reacted at 40 ° C. for 6 hours to obtain a polyamic acid solution.

After adding NMP to this polyamic acid solution (20.0 g) to dilute the polyamic acid content to 10% by mass, acetic anhydride (2.42 g) and pyridine (0.62 g) are used as imidization catalysts. And reacted at 60 ° C. for 3.5 hours. This reaction solution was put into methanol (300 ml), and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and dried under reduced pressure at 100 ° C. to obtain a polyimide powder. The imidation ratio of this polyimide was 75%, the number average molecular weight was 9651, and the weight average molecular weight was 23793.
The obtained polyimide powder was reprecipitated in methanol and stirred at 60 ° C. for 20 hours. The precipitate was filtered off and dried under reduced pressure at 100 ° C. to obtain a specific polymer powder. The imidation ratio of this specific polymer was 33%, the esterification ratio was 42%, the amide ratio was 25%, the number average molecular weight was 8314, and the weight average molecular weight was 18060.

<Example 2>
The polyimide powder obtained in Example 1 was reprecipitated in methanol and stirred at 60 ° C. for 40 hours. The precipitate was filtered off and dried under reduced pressure at 100 ° C. to obtain a specific polymer powder. The imidation ratio of this specific polymer was 27%, the esterification ratio was 48%, the amide ratio was 25%, the number average molecular weight was 9171, and the weight average molecular weight was 24207.

<Example 3>
The polyimide powder obtained in Example 1 was reprecipitated in methanol and stirred at 60 ° C. for 70 hours. The precipitate was filtered off and dried under reduced pressure at 100 ° C. to obtain a specific polymer powder. The imidation ratio of this specific polymer was 19%, the esterification ratio was 56%, the amide ratio was 25%, the number average molecular weight was 8366, and the weight average molecular weight was 20488.

<Comparative Example 1>
The polymer constituting the polyimide powder that was an intermediate polymer in Example 1 and used as a raw material for esterification was referred to as Comparative Example 1.
<Comparative example 2>
The polyamic acid polymer contained in the polyamic acid solution that was the intermediate polymer in Example 1 and was the raw material for imidization was referred to as Comparative Example 2.

<Solubility test of specific polymer>
NMP was added to and dissolved in the specific polymer powder, polyimide powder, and polyamic acid solution to obtain a polymer solution having a polymer concentration of 10% without turbidity and precipitates. BCS (butyl cellosolve), which is a poor solvent, was added until turbidity or precipitates were formed in the polymer solution, and the solubility of each polymer was evaluated from the amount of BCS added. The results are shown in the table below.
The specific polymer of the present invention was confirmed to have a high solubility of the polymer because the addition amount of the poor solvent was larger than that of the polyimide or polyamic acid.

◯: No turbidity or precipitate is observed in the polymer liquid.
X: Turbidity or precipitates are observed in the polymer liquid.

The specific polymer according to the present invention can be used in various fields including liquid crystal compounding agents.
It should be noted that the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2017-056384 filed on March 22, 2017 are cited herein as disclosure of the specification of the present invention. Incorporate.

Claims (10)

1. Polymer having a repeating unit of polyamic acid ester, a repeating unit of polyimide, and a repeating unit of polyamic acid, and having a basic group in any of the repeating units.
2. The repeating unit of the polyamic acid ester is represented by the following formula (1), the repeating unit of the polyimide is represented by the following formula (2), and the repeating unit of the polyamic acid is represented by the following formula (3). The polymer according to claim 1.
   

   

   (In the formulas (1) to (3), X ₁ , X ₂ and X ₃ are each independently a tetravalent organic group derived from a tetracarboxylic acid component. Y ₁ , Y ₂ and Y ₃ are Each independently is a divalent organic group derived from diamine, and at least one of Y ₁ , Y ₂ and Y ₃ has a basic group, R ₁ is an alkyl group having 1 to 5 carbon atoms is there.)
3. The content of the repeating unit of the polyamic acid ester, the repeating unit of the polyimide, and the repeating unit of the polyamic acid has 10 to 90 mol%, 9 to 89 mol%, and 1 to 81 mol%, respectively. The polymer according to 1 or 2.
4. The polymer according to any one of claims 1 to 3, wherein the basic group is a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a piperidine ring or a piperazine ring.
5. The Y ₁ , Y ₂ and Y ₃ having the basic group are 5 to 90 mol% with respect to all of the Y ₁ , Y ₂ and Y ₃ . Polymer.
6. The polymer according to any one of claims 2 to 5, wherein Y ₁ , Y ₂ and Y ₃ having the basic group are at least one selected from the group consisting of structures represented by the following formulas. .
   

   
7. The polymer according to any one of claims 2 to 6, wherein X1 to X3 in the formulas (1) to (3) are at least one selected from the group consisting of structures represented by the following formulas.
   

   

   
   (In the above formula, R3 to R6 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or a fluorine atom. It is a monovalent organic group having 1 to 6 carbon atoms or a phenyl group.
8. A liquid crystal aligning agent containing the polymer according to any one of claims 1 to 7.
9. A liquid crystal alignment film obtained from the liquid crystal alignment agent according to claim 8.
10. A liquid crystal display device comprising the liquid crystal alignment film according to claim 9.