Nitrogen heterocyclic ring-containing compound and preparation method and application thereof

Abstract

The invention discloses a nitrogen heterocyclic ring-containing compound as well as a preparation method and application thereof. The compound contains an N-heterocyclic structure, a large conjugated system and strong electron transfer exist in molecules, the compound has high thermal stability and photochemical stability, the compound can be used for preparing polyamide acid or polyimide, and the obtained polyimide or polyamide acid can be used for preparing liquid crystal alignment films and can be used for preparing liquid crystal display panels. The voltage holding ratio and the wear resistance of the liquid crystal alignment film are improved, the residual charge accumulation is reduced, and the liquid crystal alignment film has better long-term stability.

Description

Technical Field

[0001] The present invention relates to a nitrogen-containing heterocyclic compound and a preparation method thereof, and also relates to the application of the compound in the field of liquid crystal aligning agents, belonging to the technical field of liquid crystal alignment materials. Background Art

[0002] The polyimide-based system is a film widely used for controlling the alignment state of liquid crystal molecules, namely, a liquid crystal alignment film. However, polyimide is usually insoluble and difficult to process. Therefore, liquid crystal aligning agents for forming liquid crystal alignment films mainly contain polyimide precursors such as polyamic acid and soluble polyimide. By coating them on a glass substrate or the like and firing, a polyimide-based liquid crystal alignment film is obtained.

[0003] In recent years, with the progress of high refinement, high performance, energy saving and improvement of durability in various environments of liquid crystal display elements, problems such as a decrease in contrast due to a low voltage holding ratio in a high-temperature environment and image sticking caused by charge accumulation during long-term continuous operation have become prominent. Based on the requirements of suppressing the contrast reduction of liquid crystal display elements and reducing the afterimage phenomenon, it has become increasingly important for liquid crystal alignment films to not only exhibit good liquid crystal alignment properties and stable pretilt angles, but also have characteristics such as less residual charge when a DC voltage is applied or quick relaxation of residual charge accumulated due to the DC voltage.

[0004] To solve the above problems, there are some improved solutions in the prior art. For example, Patent CN104119929B discloses a specific liquid crystal alignment film. By adding a polyfunctional blocked isocyanate compound having an aromatic ring as an additive component to the liquid crystal aligning agent, a liquid crystal alignment film capable of obtaining a liquid crystal display element with less voltage holding ratio decrease and high reliability after long-term use can be formed. This patent adds a component with a special structure to the liquid crystal aligning agent, rather than improving the polymer structure of the liquid crystal alignment film. Summary of the Invention

[0005] The object of the present invention is to provide a nitrogen-containing heterocyclic compound, which belongs to a diamine compound, contains an N heterocyclic structure, has a large conjugated system and strong electron transfer in the molecule, has high thermal stability and photochemical stability, and can be used to prepare polyamic acid or polyimide. The obtained polyimide or polyamic acid can be used to prepare a liquid crystal alignment film, improve the voltage holding ratio, wear resistance of the liquid crystal alignment film, reduce the accumulation of residual charge, and make the liquid crystal alignment film have better long-term stability.

[0006] The present invention provides a nitrogen-containing heterocyclic compound having a structural formula shown in the following formula (B1):

[0007]

[0008] Further, in formula (B1), R1 is an alkyl group having 1 to 5 carbon atoms, a halomethylbenzyl group, a naphthylmethyl group, or a tert-butyl ester group. The alkyl group may be a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group. The halomethylbenzyl group may be a trichloromethylbenzyl group or a trifluoromethylbenzyl group.

[0009] Further, in formula (B1), R2 is hydrogen or oxygen, R3 is hydrogen or oxygen, and when R2 or R3 is oxygen, a carbonyl group is formed.

[0010] The present invention also provides a method for preparing the above nitrogen-containing heterocyclic compound, and the method includes the following steps:

[0011] (1) 1,3,8-Triazaspiro[4.5]decane-2,4-dione is subjected to an alkylation reaction with a chlorinating reagent to obtain an intermediate;

[0012] (2) The intermediate obtained in step (1) is subjected to an alkylation reaction with p-aminobenzyl chloride or 4-aminobenzoyl chloride to obtain the above nitrogen-containing heterocyclic polymer.

[0013] The present invention also provides a polyamic acid, which is obtained by a polycondensation reaction of a tetracarboxylic dianhydride and a diamine compound. The diamine compound includes a diamine compound B1, and the diamine compound B1 is at least one of the above nitrogen-containing heterocyclic compounds.

[0014] The present invention also provides a polyimide, which is obtained by imidization of the above polyamic acid.

[0015] The present invention also provides a liquid crystal aligning agent, which includes a polymer, and the polymer is one or more and is selected from the above polyamic acid and / or the above polyimide.

[0016] The present invention also provides a liquid crystal alignment film, which is prepared from the above liquid crystal aligning agent.

[0017] The present invention also provides a liquid crystal display element, which includes the above liquid crystal alignment film.

[0018] The present invention has studied and obtained a diamine compound with a nitrogen-containing heterocyclic structure having a large conjugated system and strong electron transfer in the molecule, having high thermal stability and photochemical stability. The diamine compound can be used to prepare polyimide-based high molecular compounds, and further made into a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal alignment element. The introduction of the special structure of the diamine compound can improve the high voltage holding ratio, liquid crystal alignment property, and wear resistance of the liquid crystal alignment film, and can realize the rapid relaxation of residual charges, reduce image retention, and improve the long-term stability of the liquid crystal display element. Detailed Embodiments

[0019] The present invention will be further explained and described in detail below so that those skilled in the art can have a deeper understanding of the technical solution and its advantages of the present invention. It should be understood that the following description is merely exemplary and does not limit its content.

[0020] Compound containing a nitrogen heterocycle

[0021] The present invention provides a compound containing a nitrogen heterocycle, which has a structural formula shown in the following formula (B1):

[0022]

[0023] Furthermore, in formula (B1), R1 is an alkyl group of C1-C5, a halomethylbenzyl group, a naphthylmethyl group or a tert-butyl ester group. The alkyl group of C1-C5 can be methyl, ethyl, propyl, butyl, pentyl, etc. The halomethylbenzyl group can be trichloromethylbenzyl, trifluoromethylbenzyl, etc.

[0024] Furthermore, in formula (B1), R2 is hydrogen or oxygen, R3 is hydrogen or oxygen, and when R2 or R3 is oxygen, a carbonyl group is formed.

[0025] Exemplarily, the compound containing a nitrogen heterocycle can be one of the following compounds (B1-1)-(B1-5):

[0026]

[0027]

[0028] The present invention also provides a preparation method of the above-mentioned compound containing a nitrogen heterocycle, and this method includes the following steps:

[0029] (1) 1,3,8-Triazaspiro[4.5]decane-2,4-dione undergoes an alkylation reaction with a chlorinating reagent to obtain an intermediate;

[0030] (2) The intermediate obtained in step (1) undergoes an alkylation reaction with p-aminobenzyl chloride or 4-aminobenzoyl chloride to obtain the polymer containing a nitrogen heterocycle.

[0031] Furthermore, in step (1), the chlorinating reagent includes 1-chloroalkane, halomethylbenzyl chloride, 1-chloromethylnaphthalene, tert-butyl chloroformate, etc.

[0032] Furthermore, in step (1), the molar ratio of 1,3,8-triazaspiro[4.5]decane-2,4-dione to the chlorinating reagent is 1:1 - 1.2.

[0033] Further, in step (1), the reaction is carried out in the presence of an organic solvent, and the organic solvent is an ether solvent such as tetrahydrofuran. The organic solvent serves as the reaction medium, and its amount can be adjusted according to the actual situation.

[0034] Further, in step (1), the chlorinating reagent is added dropwise. For example, 1,3,8-triazaspiro[4.5]decane-2,4-dione and the organic solvent can be first mixed, and then the mixture of the chlorinating reagent and the organic solvent is added dropwise.

[0035] Further, in step (1), the reaction temperature is 40 - 50 °C. After the raw materials are completely mixed, the reaction proceeds for 3 - 4 h.

[0036] Further, in step (2), when R2 and R3 are hydrogen, p-aminobenzyl chloride is added; when R2 and R3 are oxygen, 4-aminobenzoyl chloride is added. The molar ratio of 1,3,8-triazaspiro[4.5]decane-2,4-dione to p-aminobenzyl chloride or 4-aminobenzoyl chloride is 1:2 - 2.2.

[0037] Further, in step (2), the reaction is carried out in the presence of an organic solvent, and the organic solvent is an ether solvent such as tetrahydrofuran. The organic solvent serves as the reaction medium, and its amount can be adjusted according to the actual situation.

[0038] Further, in step (2), p-aminobenzyl chloride or 4-aminobenzoyl chloride is added dropwise. In the reaction solution after the completion of step (1), the mixture of p-aminobenzyl chloride or 4-aminobenzoyl chloride and the organic solvent can be directly added dropwise.

[0039] Further, in step (2), the reaction temperature is 60 - 65 °C. After adding p-aminobenzyl chloride or 4-aminobenzoyl chloride, the reaction proceeds for 4 - 5 h.

[0040] Polymer

[0041] The present invention provides a polymer, which is a polyamic acid or a polyimide. The polyamic acid is obtained by polycondensation of a tetracarboxylic dianhydride A and a diamine compound B, and the polyimide is obtained by imidization of a polyimide precursor.

[0042] Further, the tetracarboxylic dianhydride A required for forming the polymer includes tetracarboxylic dianhydride A1. Tetracarboxylic dianhydride A1 is a saturated tetracarboxylic dianhydride, which can be a tetracarboxylic dianhydride having a saturated alicyclic structure, a saturated aliphatic chain structure, or a saturated heterocyclic structure. Specific examples of the tetracarboxylic dianhydride having a saturated alicyclic structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 3,4-dicarboxy-1-cyclohexyl succinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic dianhydride, etc.; specific examples of the tetracarboxylic dianhydride having a saturated aliphatic chain structure include 1,2,3,4-butane tetracarboxylic dianhydride, etc.; specific examples of the tetracarboxylic dianhydride having a saturated heterocyclic structure include 2,3,4,5-tetrahydrofuran tetracarboxylic dianhydride, etc. The tetracarboxylic dianhydride A1 is not limited to these, and the tetracarboxylic dianhydride A1 can be used alone or in combination.

[0043] In order to obtain higher voltage holding characteristics and excellent liquid crystal alignment properties, the tetracarboxylic dianhydride compound A1 is preferably at least one of the following tetracarboxylic dianhydrides (A1-1) to (A1-4).

[0044]

[0045] In addition to the tetracarboxylic dianhydride A1 having an alicyclic structure, an aliphatic chain structure, or a heterocyclic structure, it can also be used in combination with tetracarboxylic dianhydrides having other structures. The tetracarboxylic dianhydride having other structures can be a tetracarboxylic dianhydride A2 having an aromatic structure. Examples of the tetracarboxylic dianhydride having an aromatic structure include pyromellitic dianhydride, 3,3,4,4'-biphenyltetracarboxylic dianhydride, 2,2,3,3'-biphenyltetracarboxylic dianhydride, 2,3,3,4'-biphenyltetracarboxylic dianhydride, 3,3,4,4'-benzophenonetetracarboxylic dianhydride, 2,3,3,4'-benzophenone tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl) ether dianhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, etc., but are not limited to these. Similar tetracarboxylic dianhydrides with the above structures can also be used in combination with one or more of the tetracarboxylic dianhydrides A1 having an alicyclic structure, an aliphatic chain structure, or a heterocyclic structure.

[0046] In order to make the liquid crystal have higher voltage holding characteristics, excellent liquid crystal alignment properties, and the effect of further reducing the accumulated charge, the tetracarboxylic dianhydride compound A2 is preferably at least one of the following compositions (A2-1) to (A2-2).

[0047]

[0048] More importantly, the diamine compound B includes a diamine compound B1, and the diamine compound B1 is selected from at least one of the nitrogen-containing heterocyclic compounds represented by the above formula (B1), preferably selected from at least one of the compounds of the above formula (B1-1)-(B1-5). Through in-depth research, the present invention improves the structure of the above polymer by using a specific diamine compound containing an N heterocycle. The diamine compound B1 contains an N heterocyclic structure, has a large conjugated system and strong electron transfer in its molecule, has high thermal stability and photochemical stability, and is also easy to modify the structure. By different selections of R1, R2, and R3, various types of functional groups can be introduced, and these functional groups can be introduced into the polymer chain through different polymerization methods to form a polymer material. The polymer prepared from the diamine compound B1 can be used in the manufacture of a liquid crystal aligning agent, and the formed liquid crystal alignment film can not only have high liquid crystal alignment and voltage holding ratio, but also can achieve rapid relaxation of residual charge and high wear resistance to ensure the long-term stability of the liquid crystal display element.

[0049] Furthermore, in addition to the diamine compound B1, it can also be used in combination with diamine compounds of other structures. The diamine compounds of other structures can be defined as diamine compound B2, and there are no particular restrictions on the diamine compound B2. Specifically, 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethylcyclohexylamine, 4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 1,2-bis[(4-aminophenyl)-2-propyl]benzene, 4,4'-diaminodiphenylamine and 4,4'-diaminodiphenylurea, 4,4'-diaminodiphenyl sulfone, 3,6-diaminocarbazole, 2,3-diaminopyridine, 1,5-diaminonaphthalene, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, benzidine, 2,4-diamino-6-hydroxypyrimidine, 2,4-diamino-1,3,5-triazine, 2,6-diaminopurine, 3,5-diamino-1,3,5-triazole, etc. can be listed. These diamine compounds B2 can be used alone or in combination.

[0050] Furthermore, the diamine compound B2 is preferably at least one of the following compounds (B2-1) to (B2-3). When the diamine compound B2 is used in combination with the diamine compound B1, it has less charge residue.

[0051]

[0052] Further, the molar amount of the tetracarboxylic dianhydride A1 is 20-100% of the molar amount of the tetracarboxylic dianhydride A, such as 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, preferably 60-80%.

[0053] Further, the molar amount of the diamine compound B1 is 10-50% of the total molar amount of the diamine compound B, such as 10%, 20%, 30%, 40%, 50%. Through experimental verification, when the maximum usage amount of the diamine compound B1 does not exceed 30% of the total molar amount of the diamine compound B, the obtained liquid crystal alignment film can achieve the expected orientation and voltage holding ratio. Therefore, preferably, the molar amount of the diamine compound B1 is 10-30% of the total molar amount of the diamine compound B. The molar amount of the diamine compound B2 is 50-90% of the total molar amount of the diamine compound B, such as 50%, 60%, 70%, 80%, 90%, preferably 70-90%. The diamine compound B2 can not only make up for the deficiency of the diamine compound B1, but also well inhibit the afterimage problem caused by residual charges.

[0054] Manufacturing method of polyamic acid

[0055] The polyamic acid used in the present invention can be synthesized by reacting the tetracarboxylic dianhydride A and the diamine compound B as described above.

[0056] Specifically, the polyamic acid can be manufactured by reacting the tetracarboxylic dianhydride component A and the diamine compound component B in the presence of an organic solvent at -20°C to 150°C, preferably 5 to 100°C, more preferably 10 to 60°C for 30 minutes to 24 hours, preferably for 2 to 12 hours.

[0057] The organic solvent used for the above reaction has no other special limitations as long as it can dissolve the generated polyamic acid. Examples include at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-methylcaprolactam, N-methyl-2-pyrrolidone, γ-butyrolactone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol methyl ethyl ether, ethylene glycol dimethyl ether, dimethyl sulfoxide, etc., preferably γ-butyrolactone or N-methylpyrrolidone (NMP). These solvents can be used alone or in combination. In addition, since water in the solvent inhibits the polymerization reaction and causes hydrolysis of the generated polyamic acid, a dehydrated and dried solvent is preferably used. From the perspective of difficult precipitation of the polymer and easy obtaining of high molecular weight, the concentration of the polyamic acid in the organic solvent is preferably 1-20 wt%, more preferably 5-15 wt%.

[0058] As described above, a reaction solution containing polyamic acid dissolved therein can be obtained. This reaction solution can be directly supplied for the preparation of a liquid crystal aligning agent, or the polyamic acid contained in the reaction solution can be separated and then supplied for the preparation of the liquid crystal aligning agent, or the separated polyamic acid can be purified and then supplied for the preparation of the liquid crystal aligning agent.

[0059] For the separation and purification of polyamic acid, while sufficiently stirring the obtained solution of polyamic acid, a poor solvent is injected, whereby the polymer precipitates, and the polymer is recovered by filtration. The operation of redissolving the precipitated and recovered polymer in a solvent and then performing reprecipitation and recovery is repeated several times, impurities in the polymer can be reduced, and then drying at room temperature or by heating can obtain a purified polyamic acid solid. There is no particular limitation on the poor solvent, and it can be alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc. Specific examples of such poor solvents include methanol, ethanol, isopropanol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, ethyl lactate, butyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate, diethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol monoethyl ether acetate, diglyme, diglycol diethyl ether, diglycol monomethyl ether, diglycol monoethyl ether, diglycol monomethyl ether acetate, diglycol monoethyl ether acetate, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene, etc.

[0060] Method for manufacturing polyimide

[0061] Polyimide can be manufactured by imidizing polyamic acid. It can be synthesized by dehydrating and cyclizing the polyamic acid as described above. The dehydration and cyclization of polyamic acid can be carried out by heating the polyamic acid (physical imidization method), or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration and cyclization catalyst to this solution, and heating as required (chemical imidization method). Chemical imidization is preferred because the imidization reaction is carried out at a relatively low temperature and the molecular weight of the polymer is not easily reduced during the imidization process.

[0062] Chemical imidization can be carried out as follows: A dehydrating agent and a dehydrating and ring-closing catalyst are added to the polyamic acid solution. As the dehydrating agent, acid anhydrides such as acetic anhydride, propionic anhydride, trifluoroacetic anhydride, etc. can be used. Among them, when acetic anhydride is used, it is easier to purify at the end of the reaction, so it is preferred. In addition, as the dehydrating and ring-closing catalyst, tertiary amines such as pyridine, collidine, dimethylpyridine, triethylamine, etc. can be used, but it is not limited to these. As the organic solvent used in the dehydrating and ring-closing reaction, the solvents used in the synthesis of polyamic acid can be listed.

[0063] The temperature for carrying out the imidization reaction is 0°C to 140°C, preferably 10°C to 100°C. The reaction time can be carried out within 1 to 60 h. The amount of the dehydrating and ring-closing catalyst is 0.5 to 30 times the molar amount of the polyamic acid group, preferably 2 to 20 times the molar amount, and the amount of the dehydrating agent is 1 to 50 times the molar amount of the polyamic acid group, preferably 3 to 30 times the molar amount. The imidization rate of the obtained polymer does not necessarily have to reach 100%, and can be arbitrarily adjusted according to the use and purpose. The imidization rate can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

[0064] For the solution of the polyimide obtained above, it can be poured into a poor solvent, so that the polymer can precipitate, and the polymer can be recovered by filtration. The precipitated polymer is redissolved in a solvent and subjected to the operation of reprecipitation and recovery. Repeating this process several times can reduce the impurities in the polymer, and then drying at room temperature or by heating can obtain the purified polymer solid.

[0065] The poor solvents that can be listed are 2-propanol, hexane, heptane, methyl ethyl ketone, methyl isobutyl ketone, water, methanol, ethanol, butyl cellosolve, acetone, toluene, etc., and methanol, ethanol, 2-propanol, acetone, etc. are preferred.

[0066] For the molecular weight of the polyimide, in terms of the weight-average molecular weight (Mw), it is preferably 2000 to 500000, more preferably 5000 to 300000, and even more preferably 10000 to 100000.

[0067] Solution viscosities of polyamic acid and polyimide polymer

[0068] The polyamic acid and polyimide polymers used in the present invention, when respectively prepared into solutions with a concentration of 5 wt%, preferably have a solution viscosity of 10 to 500 mPa·s, and more preferably have a solution viscosity of 20 to 300 mPa·s.

[0069] The solution viscosity (mPa·s) of the above polymer is the value measured at 25°C with an E-type rotational viscometer for a 5 wt% concentration polymer solution prepared with a good solvent (such as N-methyl-2-pyrrolidone, γ-butyrolactone, etc.) of the polymer.

[0070] Liquid crystal aligning agent

[0071] The present invention provides a liquid crystal aligning agent, and the components of the liquid crystal aligning agent include a polymer, and the polymer is selected from the above polyimide or / and polyamic acid polymer, and the polymer can be one kind or multiple kinds.

[0072] Furthermore, the liquid crystal aligning agent further includes a solvent, and there is no particular limitation as long as the solvent can dissolve the specific polymer of the present invention. Examples include at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-methylcaprolactam, N-methyl-2-pyrrolidone, γ-butyrolactone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol methyl ethyl ether, ethylene glycol dimethyl ether, dimethyl sulfoxide, etc. In addition, even a solvent that cannot uniformly dissolve the polymer component when present alone can be mixed with the above organic solvents as long as the polymer does not precipitate.

[0073] Furthermore, the weight ratio of the polymer to the solvent is 1:10 - 100, such as 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100.

[0074] Furthermore, the polymer component in the liquid crystal aligning agent can all be the polyimide substance of the present invention, or can also contain other polymers. Examples include acrylic polymers, methacrylic polymers, cellulose polymers, polystyrene, polysiloxanes, polyamides, etc. The content of these other polymers in the liquid crystal aligning agent is preferably 1 - 90 wt%, more preferably 1 - 30 wt%.

[0075] In the liquid crystal aligning agent of the present invention, a solvent that can improve the coating film property and surface smoothness of the liquid crystal aligning agent coating may also be included. Examples include ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, 1-pentanol, 2-pentanol, 3-pentanol, ethylene glycol, 1-methoxy-2-propanol, 2-methyl-1-butanol, isopentanol, tert-pentanol, 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, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, butyl cellosolve acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, furfuryl alcohol, diethylene glycol, propylene glycol monobutyl ether, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, etc. Two or more of these solvents can be used in combination.

[0076] Preparation of Liquid Crystal Alignment Film

[0077] The present invention provides a liquid crystal alignment film, which is prepared from the above liquid crystal aligning agent.

[0078] The liquid crystal alignment film of the present invention is a film obtained by coating the above liquid crystal aligning agent on a substrate, followed by drying, baking, and alignment treatment. As the substrate for coating the liquid crystal aligning agent of the present invention, as long as it is a substrate with high transparency, there are no other special limitations, and glass substrates, acrylic substrates, silicon nitride substrates, polycarbonate substrates, polyurethane substrates, trimethylpentene substrates, triacetate cellulose substrates, cellulose acetate butyrate substrates, etc. can be used. In addition, from the perspective of simplifying the process, it is preferably to use a substrate with an ITO electrode for driving liquid crystals, etc. In addition, in a reflective liquid crystal display element, if only one side of the substrate is used, an opaque material such as a silicon wafer can be used, and in this case, an electrode that can reflect light, such as aluminum, can also be used.

[0079] As the coating method of the liquid crystal aligning agent of the present invention, printing methods such as screen printing, offset printing, and flexographic printing, spraying methods, spin coating methods, inkjet methods, etc. can be cited. From the aspect of production efficiency, the printing method is often used in industrial production and can also be appropriately used in the present invention.

[0080] The liquid crystal aligning agent is coated by the above coating method, and the formed coating film is baked to become a cured film. The drying process after coating the liquid crystal aligning agent is not necessary, and the time from coating to baking for each substrate is not fixed. This drying only needs to remove the solvent until the shape of the coating film will not be deformed due to handling of the substrate, etc., and there is no particular limitation on the drying means. For example, it can be cited to dry at 50 - 120°C, preferably 60 - 100°C for 1 minute - 10 minutes, preferably 2 - 5 minutes, and then cure at 150 - 300°C, preferably 200 - 240°C for 5 - 120 minutes, preferably 10 - 30 minutes. The thickness of the cured film is not particularly limited. When the film thickness is too thin, the reliability of the liquid crystal display element may be reduced, so it is 5 - 300 nm, preferably 10 - 200 nm.

[0081] As a method for aligning the film, methods such as brushing method and photo-alignment method can be cited, and the liquid crystal aligning agent of the present invention has better effects when used in the brushing method.

[0082] Fabrication of Liquid Crystal Display Element

[0083] The present invention provides a liquid crystal display element, which includes the above liquid crystal alignment film. After obtaining the substrate with the liquid crystal alignment film, the liquid crystal display element can be fabricated by common methods.

[0084] Specific methods for fabricating the liquid crystal display element include: First, prepare a pair of substrates with liquid crystal alignment films. Then, scatter spacers on the liquid crystal alignment film of a single substrate, and paste it on the other substrate with the liquid crystal alignment film surface as the inner side, inject liquid crystal under reduced pressure and seal it. Or, after dropping liquid crystal on the liquid crystal alignment film surface where spacers are scattered, paste the substrates and seal them. The thickness of the spacers at this time is preferably 1 - 30 μm, more preferably 2 - 10 μm.

[0085] The following further elaborates on the present invention in combination with specific embodiments, but the present invention is not limited to the following embodiments. The methods are conventional methods unless otherwise specified. The materials can be obtained from public commercial channels unless otherwise specified.

[0086] The molecular weights of the polyimide and polyamic acid obtained in the following examples were measured by the GPC method (Shimadzu Corporation, Japan, gel permeation chromatography), the mobile phase was N-methylpyrrolidone, and the obtained molecular weights were all weight-average molecular weights (Mw).

[0087] The following lists examples for more specific description of the present invention, but the present invention is not limited to these examples. The abbreviations of the components used in the following examples are as follows:

[0088] NMP: N-methyl-2-pyrrolidone

[0089] BC: Butyl Cellosolve

[0090] Tetracarboxylic dianhydride compound A:

[0091]

[0092] Diamine compound B:

[0093]

[0094]

[0095] Synthesis of nitrogen-containing heterocyclic monomers

[0096] Synthesis of monomer B1-1

[0097]

[0098] Add 20 g (0.12 mol) of 1,3,8-triazaspiro[4.5]decane-2,4-dione and 100 ml of tetrahydrofuran into a three-necked flask, heat up to 40 °C, add a mixture of 10.2 g (0.13 mol) of 1-chloropropane and 50 ml of tetrahydrofuran into the constant pressure dropping funnel, slowly drip it. After the 1-chloropropane is completely added, keep the temperature for reaction for 3 h. Then slowly drip a mixed solution of 34 g (0.24 mol) of p-aminobenzyl chloride and 200 ml of tetrahydrofuran with the constant pressure dropping funnel, and heat up to 60 °C. After dropping, keep the temperature for reaction for 4 h. After the reaction, distill off the reaction solvent under reduced pressure to obtain a pale yellow solid powder. Then dissolve the solid powder in 1,4-dioxane at 60 °C, cool it to precipitate the solid and filter it. After drying, a white solid powder is obtained with a yield of 90%.

[0099] The NMR information of B1-1 is as follows:

[0100] 1 H NMR (500 MHz, DMSO): δ: 7.74 (m, 4H), 6.48 (m, 4H), 4.91 (s, 4H), 4.36 (s, 2H), 3.54 (s, 2H), 3.14 (t, 2H), 2.41 (m, 4H), 2.08 (m, 2H), 1.83 (m, 2H), 1.61 (m, 2H), 0.87 (t, 3H).

[0101] Synthesis of monomer B1-2

[0102]

[0103] 20 g (0.12 mol) of 1,3,8-triazaspiro[4.5]decane-2,4-dione and 100 ml of tetrahydrofuran were added to a three-necked flask, and the temperature was raised to 40 °C. A mixed solution of 25.3 g (0.13 mol) of 4-(trifluoromethyl)benzyl chloride and 50 ml of tetrahydrofuran was added to a constant pressure dropping funnel and slowly dropped. After the addition of 4-(trifluoromethyl)benzyl chloride was completed, the reaction was carried out at a constant temperature for 3 h. Then, a mixed solution of 34 g (0.24 mol) of 4-aminobenzyl chloride and 200 ml of tetrahydrofuran was slowly dropped using a constant pressure dropping funnel, and the temperature was raised to 60 °C. After the dropping was completed, the reaction was carried out at a constant temperature for 4 h. After the reaction, the reaction solvent was removed by distillation under reduced pressure to obtain a white solid powder. Then, the solid powder was dissolved in 1,4-dioxane at 60 °C, and the solid was precipitated and filtered after cooling, and a white solid powder was obtained after drying, with a yield of 83%.

[0104] The NMR information of B1-2 is as follows:

[0105] 1 H NMR (500 MHz, DMSO): δ: 7.54 (m, 2H), 7.15 - 7.12 (m, 6H), 6.46 (m, 4H), 4.98 (s, 2H), 4.93 (s, 4H), 4.33 (s, 2H), 3.52 (s, 2H), 2.45 (m, 4H), 2.06 (m, 2H), 1.86 (m, 2H).

[0106] Synthesis of monomer B1-3

[0107]

[0108] 20 g (0.12 mol) of 1,3,8-triazaspiro[4.5]decane-2,4-dione and 100 ml of tetrahydrofuran were added to a three-necked flask, and the temperature was raised to 40 °C. A mixed solution of 23 g (0.13 mol) of 1-chloromethylnaphthalene and 50 ml of tetrahydrofuran was added to a constant pressure dropping funnel and slowly dropped. After the addition of 1-chloromethylnaphthalene was completed, the reaction was carried out at a constant temperature for 3 h. Then, a mixed solution of 34 g (0.24 mol) of 4-aminobenzyl chloride and 200 ml of tetrahydrofuran was slowly dropped using a constant pressure dropping funnel, and the temperature was raised to 60 °C. After the dropping was completed, the reaction was carried out at a constant temperature for 4 h. After the reaction, the reaction solvent was removed by distillation under reduced pressure to obtain a pale yellow solid powder. Then, the solid powder was dissolved in 1,4-dioxane at 60 °C, and the solid was precipitated and filtered after cooling, and a pale yellow solid powder was obtained after drying, with a yield of 85%.

[0109] The NMR information of B1-3 is as follows:

[0110] 1HNMR (500 MHz, DMSO): δ: 8.01 - 7.97 (m, 3H), 7.55 - 7.52 (m, 2H), 7.28 (m, 1H), 7.12 (m, 4H), 6.99 (d, 1H), 6.46 (d, 4H), 5.31 (s, 2H), 4.89 (s, 4H), 4.32 (s, 2H), 3.50 (s, 2H), 2.42 (m, 4H), 2.05 (m, 2H), 1.85 (m, 2H).

[0111] Synthesis of monomer B1 - 4

[0112]

[0113] Add 20 g (0.12 mol) of 1,3,8 - triazaspiro[4.5]decane - 2,4 - dione and 100 ml of tetrahydrofuran into a three - necked flask, heat up to 40 °C. In a constant - pressure dropping funnel, add a mixed solution of 17.8 g (0.13 mol) of tert - butyl chloroformate and 50 ml of tetrahydrofuran, and slowly drip it. After the tert - butyl chloroformate is added dropwise, keep the temperature for reaction for 3 h. Then slowly drip a mixed solution of 34 g (0.24 mol) of p - aminobenzyl chloride and 200 ml of tetrahydrofuran with a constant - pressure dropping funnel, and heat up to 60 °C. After dropping, keep the temperature for reaction for 4 h. After the reaction, distill off the reaction solvent under reduced pressure to obtain a pale yellow solid powder. Then dissolve the solid powder in 1,4 - dioxane at 60 °C, cool it to make the solid precipitate and filter it. After drying, a white solid powder is obtained with a yield of 80%.

[0114] The NMR information of B1 - 4 is as follows:

[0115] 1 HNMR (500 MHz, DMSO): δ: 7.11 (d, 4H), 6.45 (d, 4H), 4.90 (s, 4H), 4.34 (s, 2H), 3.53 (s, 2H), 2.44 (m, 4H), 2.03 (m, 2H), 1.83 (m, 2H),

[0116] 1.42 (s, 9H).

[0117] Synthesis of monomer B1 - 5

[0118]

[0119] Add 20 g (0.12 mol) of 1,3,8-triazaspiro[4.5]decane-2,4-dione and 100 ml of tetrahydrofuran into a three-necked flask, heat up to 40 °C, add a mixed solution of 23 g (0.13 mol) of 1-chloromethylnaphthalene and 50 ml of tetrahydrofuran in a constant pressure dropping funnel, and slowly drip. After the 1-chloromethylnaphthalene is completely added, keep the temperature for reaction for 3 h. Then slowly drip a mixed solution of 37.3 g (0.24 mol) of 4-aminobenzoyl chloride and 200 ml of tetrahydrofuran with a constant pressure dropping funnel, and heat up to 60 °C. After dropping, keep the temperature for reaction for 4 h. After the reaction, remove the reaction solvent by distillation under reduced pressure to obtain a yellow solid powder. Then dissolve the solid powder in 1,4-dioxane at 60 °C, cool to precipitate the solid and filter, and dry to obtain a pale yellow solid powder with a yield of 86%.

[0120] The NMR information of B1-5 is as follows:

[0121] 1 HNMR(500MHz, DMSO): δ: 7.99 - 8.02(m, 3H), 7.53 - 7.57(m, 6H), 7.26(m, 1H), 6.99(d, 1H), 6.54(d, 4H), 5.49(s, 4H), 5.32(s, 2H), 3.59(m, 4H), 2.23(m, 2H), 1.98(m, 2H).

[0122] Synthesis of the polymer

[0123] Synthesis Example 1

[0124] Introduce N2 into a 500 mL four-necked flask equipped with a stirring device, and successively add 5.0 g (0.012 mol) of B1-1, 12.25 g (0.047 mol) of B2-1, and 181.79 g of NMP. After complete dissolution, add 9.31 g (0.042 mol) of A1-1 and 25.52 g (0.018 mol) of A2-2. React at room temperature for 24 hours, then successively add 14.0 g (0.18 mol) of pyridine and 30.12 g (0.30 mol) of acetic anhydride, and react at 50 °C for 5 hours for imidization reaction. Then pour the reaction solution into ethanol to precipitate, filter by suction to obtain a pale yellow powdery solid. Wash the obtained solid with ethanol, then dissolve the solid in NMP, and then precipitate in ethanol, filter by suction to refine the polyimide. Finally, vacuum dry the refined polyimide for standby. First dissolve the vacuum-dried polyimide solid in NMP, then add BC to prepare a solution. The content of polyimide in the solution is 5 wt%, NMP is 70 wt%, and BC is 25 wt%, denoted as polyimide solution PI-1. The molecular weight Mw of the polyimide is measured by GPC to be 40876 g / mol, and the viscosity is measured to be 36.33 mPa·s.

[0125] Synthesis Example 2

[0126] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 6.0 g (0.011 mol) of B1-2, 11.53 g (0.045 mol) of B2-1, and 178.40 g of NMP were added in sequence. After complete dissolution, 8.76 g (0.039 mol) of A1-1 and 25.19 g (0.017 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 13.29 g (0.17 mol) of pyridine and 28.59 g (0.28 mol) of acetic anhydride were added in sequence, and the reaction was carried out at 50 °C for 5 hours for imidization reaction. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP, and then precipitated in ethanol again, filtered by suction to refine the polyimide. Finally, the refined polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-2. The molecular weight Mw measured by GPC was 41366 g / mol, and the viscosity was measured to be 36.76 mPa·s.

[0127] Synthesis Example 3

[0128] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 6.0 g (0.012 mol) of B1-3, 11.93 g (0.046 mol) of B2-1, and 183.39 g of NMP were added in sequence. After complete dissolution, 9.06 g (0.040 mol) of A1-1 and 25.37 g (0.017 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 13.76 g (0.17 mol) of pyridine and 29.61 g (0.29 mol) of acetic anhydride were added in sequence, and the reaction was carried out at 50 °C for 5 hours for imidization reaction. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP, and then precipitated in ethanol again, filtered by suction to refine the polyimide. Finally, the refined polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-3. The molecular weight Mw measured by GPC was 40113 g / mol, and the viscosity was measured to be 35.35 mPa·s.

[0129] Synthesis Example 4

[0130] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 5.0 g (0.010 mol) of B1-4, 10.77 g (0.042 mol) of B2-1, and 163.22 g of NMP were added in sequence. After complete dissolution, 8.18 g (0.036 mol) of A1-1 and 4.85 g (0.016 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 12.34 g (0.16 mol) of pyridine and 26.54 g (0.26 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP and precipitated in ethanol again, and filtered by suction to purify the polyimide. Finally, the purified polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-4. The molecular weight Mw measured by GPC was 39913 g / mol, and the viscosity was measured to be 35.03 mPa·s.

[0131] Synthesis Example 5

[0132] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 6.0 g (0.011 mol) of B1-5, 11.32 g (0.044 mol) of B2-1, and 175.76 g of NMP were added in sequence. After complete dissolution, 8.59 g (0.038 mol) of A1-1 and 5.10 g (0.016 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 13.05 g (0.17 mol) of pyridine and 28.07 g (0.28 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP and precipitated in ethanol again, and filtered by suction to purify the polyimide. Finally, the purified polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-5. The molecular weight Mw measured by GPC was 40072 g / mol, and the viscosity was measured to be 35.56 mPa·s.

[0133] Synthesis Example 6

[0134] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 6.0 g (0.011 mol) of B1-5, 8.78 g (0.044 mol) of B2-2, and 161.33 g of NMP were added in sequence. After complete dissolution, 18.59 g (0.038 mol) of A1 and 25.10 g (0.016 mol) of A2 were added. After reacting at room temperature for 24 hours, 13.05 g (0.17 mol) of pyridine and 28.07 g (0.28 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP, and then precipitated in ethanol again, filtered by suction to refine the polyimide. Finally, the refined polyimide was dried under vacuum for standby. The polyimide solid after vacuum drying was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-6. The molecular weight Mw measured by GPC was 41131 g / mol, and the viscosity was measured to be 36.06 mPa·s.

[0135] Synthesis Example 7

[0136] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 6.0 g (0.011 mol) of B1-5, 10.00 g (0.044 mol) of B2-3, and 168.29 g of NMP were added in sequence. After dissolution, 18.59 g (0.038 mol) of A1 and 25.10 g (0.016 mol) of A2 were added. After reacting at room temperature for 24 hours, 13.05 g (0.17 mol) of pyridine and 28.07 g (0.28 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP, and then precipitated in ethanol again, filtered by suction to refine the polyimide. Finally, the refined polyimide was dried under vacuum for standby. The polyimide solid after vacuum drying was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-7. The molecular weight Mw measured by GPC was 40195 g / mol, and the viscosity was measured to be 35.88 mPa·s.

[0137] Synthesis Example 8

[0138] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 6.0 g (0.011 mol) of B1-5, 10.00 g (0.044 mol) of B2-3, and 168.29 g of NMP were added in sequence. After complete dissolution, 8.59 g (0.038 mol) of A1-2 and 25.10 g (0.016 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 13.05 g (0.17 mol) of pyridine and 28.07 g (0.28 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP, and then precipitated in ethanol again, filtered by suction to refine the polyimide. Finally, the refined polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-8. The molecular weight Mw measured by GPC was 39897 g / mol, and the viscosity was measured to be 35.45 mPa·s.

[0139] Synthesis Example 9

[0140] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 3.5 g (0.006 mol) of B1-5, 13.13 g (0.058 mol) of B2-3, and 184.77 g of NMP were added in sequence. After complete dissolution, 10.03 g (0.045 mol) of A1-2 and 25.95 g (0.019 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 15.19 g (0.19 mol) of pyridine and 32.96 g (0.32 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP, and then precipitated in ethanol again, filtered by suction to refine the polyimide. Finally, the refined polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-9. The molecular weight Mw measured by GPC was 41021 g / mol, and the viscosity was measured to be 34.85 mPa·s.

[0141] Synthesis Example 10

[0142] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 9.0 g (0.016 mol) of B1-5, 8.75 g (0.038 mol) of B2-3, and 178.20 g of NMP were added in sequence. After complete dissolution, 28.59 g (0.038 mol) of A1-2 and 25.10 g (0.016 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 12.81 g (0.16 mol) of pyridine and 27.81 g (0.27 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP and precipitated in ethanol again, and filtered by suction to refine the polyimide. Finally, the refined polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-10. The molecular weight Mw measured by GPC was 39772 g / mol, and the viscosity was measured to be 35.30 mPa·s.

[0143] Synthesis Example 11

[0144] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 8.0 g (0.031 mol) of B2-1, 7.07 g (0.031 mol) of B2-3, and 173.13 g of NMP were added in sequence. After complete dissolution, 9.72 g (0.043 mol) of A1-1 and 25.76 g (0.019 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 14.71 g (0.19 mol) of pyridine and 31.65 g (0.31 mol) of acetic anhydride were added in sequence, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, filtered by suction to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP and precipitated in ethanol again, and filtered by suction to refine the polyimide. Finally, the refined polyimide was vacuum dried for standby. The vacuum-dried polyimide solid was first dissolved in NMP, and then BC was added to prepare a solution. The polymer content in the solution was 5 wt%, NMP was 70 wt%, and BC was 25 wt%, denoted as polyimide solution PI-11. The molecular weight Mw measured by GPC was 40237 g / mol, and the viscosity was measured to be 34.97 mPa·s.

[0145] Synthesis Example 12

[0146] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 7.0 g (0.035 mol) of B2-2, 7.98 g (0.035 mol) of B2-3, and 183.92 g of NMP were successively added. After complete dissolution, 10.97 (0.049 mol) of A1-1 and 6.51 g (0.021 mol) of A2-2 were added. After reacting at room temperature for 24 hours, 16.61 g (0.21 mol) of pyridine and 35.73 g (0.35 mol) of acetic anhydride were successively added, and the imidization reaction was carried out at 50 °C for 5 hours. Then the reaction solution was poured into ethanol for precipitation, and suction filtration was carried out to obtain a pale yellow powdery solid. The obtained solid was washed with ethanol, then the solid was dissolved in NMP, and then precipitated in ethanol again, followed by suction filtration to purify the polyimide. Finally, the purified polyimide was dried under vacuum for standby. The polyimide solid after vacuum drying was first dissolved in NMP, and then BC was added to prepare a solution with a polymer content of 5 wt%, NMP of 70 wt%, and BC of 25 wt%, denoted as polyimide solution PI-12. The molecular weight Mw measured by GPC was 41437 g / mol, and the viscosity was measured to be 35.18 mPa·s.

[0147] Synthesis Example 13

[0148] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 5.00 g (0.01 mol) of B1-4, 10.77 g (0.042 mol) of B2-1, and 163.22 g of NMP were successively added. After dissolution, 8.18 g (0.036 mol) of A1-2 and 4.85 g (0.016 mol) of A2-2 were added. After reacting at room temperature for 24 hours, NMP and BC were successively added to prepare a solution with a polymer content of 5 wt%, NMP of 70 wt%, and BC of 25 wt%, denoted as polyamic acid solution PAA-1. The molecular weight Mw measured by GPC was 39768 g / mol, and the viscosity was measured to be 36.05 mPa·s.

[0149] Synthesis Example 14

[0150] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 6.00 g (0.013 mol) of B1-4, 10.02 g (0.050 mol) of B2-2, and 179.40 g of NMP were added in sequence. After dissolution, 29.82 g (0.044 mol) of A1 and 25.82 g (0.019 mol) of A2 were added. After reacting at room temperature for 24 hours, NMP and BC were added in sequence to prepare a solution with a polymer content of 5 wt%, NMP of 70 wt%, and BC of 25 wt%, denoted as polyamic acid solution PAA-2. The molecular weight Mw measured by GPC was 41342 g / mol, and the viscosity measured was 35.81 mPa·s.

[0151] Synthesis Example 15

[0152] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 5.00 g (0.010 mol) of B1-4, 9.52 g (0.042 mol) of B2-3, and 156.12 g of NMP were added in sequence. After dissolution, 28.18 g (0.036 mol) of A1 and 24.85 g (0.016 mol) of A2 were added. After reacting at room temperature for 24 hours, NMP and BC were added in sequence to prepare a solution with a polymer content of 5 wt%, NMP of 70 wt%, and BC of 25 wt%, denoted as polyamic acid solution PAA-3. The molecular weight Mw measured by GPC was 40943 g / mol, and the viscosity measured was 34.87 mPa·s.

[0153] Synthesis Example 16

[0154] N2 was introduced into a 500 mL four-necked flask equipped with a stirring device. 8.00 g (0.031 mol) of B2-1, 7.07 g (0.031 mol) of B2-3, and 173.13 g of NMP were added in sequence. After dissolution, 29.72 g (0.043 mol) of A1 and 25.76 g (0.019 mol) of A2 were added. After reacting at room temperature for 24 hours, NMP and BC were added in sequence to prepare a solution with a polymer content of 5 wt%, NMP of 70 wt%, and BC of 25 wt%, denoted as polyamic acid solution PAA-4. The molecular weight Mw measured by GPC was 41551 g / mol, and the viscosity measured was 35.17 mPa·s.

[0155] Example 1

[0156] 40.00 g of the polyimide solution PI-1 obtained in Synthesis Example 1 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 1.

[0157] Example 2

[0158] 40.00 g of the polyimide solution PI-2 obtained in Synthesis Example 2 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 2.

[0159] Example 3

[0160] 40.00 g of the polyimide solution PI-3 obtained in Synthesis Example 3 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 2.

[0161] Example 4

[0162] 40.00 g of the polyimide solution PI-4 obtained in Synthesis Example 4 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 4.

[0163] Example 5

[0164] 40.00 g of the polyimide solution PI-5 obtained in Synthesis Example 5 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 5.

[0165] Example 6

[0166] 40.00 g of the polyimide solution PI-6 obtained in Synthesis Example 6 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 6.

[0167] Example 7

[0168] 40.00 g of the polyimide solution PI-7 obtained in Synthesis Example 7 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 7.

[0169] Example 8

[0170] 40.00 g of the polyimide solution PI-8 obtained in Synthesis Example 8 and 60.00 g of the polyamic acid solution PAA-1 obtained in Synthesis Example 13 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 8.

[0171] Example 9

[0172] 40.00 g of the polyimide solution PI-8 obtained in Synthesis Example 8 and 60.00 g of the polyamic acid solution PAA-2 obtained in Synthesis Example 14 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 9.

[0173] Example 10

[0174] 40.00 g of the polyimide solution PI-8 obtained in Synthesis Example 8 and 60.00 g of the polyamic acid solution PAA-3 obtained in Synthesis Example 15 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 10.

[0175] Example 11

[0176] 40.00 g of the polyimide solution PI-9 obtained in Synthesis Example 9 and 60.00 g of the polyamic acid solution PAA-2 obtained in Synthesis Example 14 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 11.

[0177] Example 12

[0178] 40.00 g of the polyimide solution PI-10 obtained in Synthesis Example 10 and 60.00 g of the polyamic acid solution PAA-2 obtained in Synthesis Example 14 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 12.

[0179] Example 13

[0180] The polyimide solution PI-8 obtained in Synthesis Example 8 was designated as the liquid crystal aligning agent 13.

[0181] Example 14

[0182] The polyamic acid solution PAA-2 obtained in Synthesis Example 14 was designated as the liquid crystal aligning agent 14.

[0183] Example 15

[0184] 40.00 g of the polyimide solution PI-11 obtained in Synthesis Example 11 and 60.00 g of the polyamic acid solution PAA-2 obtained in Synthesis Example 14 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 15.

[0185] Example 16

[0186] 40.00 g of the polyimide solution PI-12 obtained in Synthesis Example 12 and 60.00 g of the polyamic acid solution PAA-2 obtained in Synthesis Example 14 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 16.

[0187] Example 17

[0188] 40.00 g of the polyimide solution PI-8 obtained in Synthesis Example 8 and 60.00 g of the polyamic acid solution PAA-4 obtained in Synthesis Example 16 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 17.

[0189] Comparative Example 1

[0190] 40.00 g of the polyimide solution PI-11 obtained in Synthesis Example 11 and 60.00 g of the polyamic acid solution PAA-4 obtained in Synthesis Example 16 were stirred at room temperature for 3 hours to obtain a liquid crystal aligning agent 18.

[0191] Performance Test

[0192] (1) Fabrication of FFS-Driven Liquid Crystal Cell

[0193] On a glass substrate with electrodes, the liquid crystal aligning agents prepared in each example and comparative example were spin-coated. On the substrate used, an ITO electrode having a dense pattern and constituting a counter electrode was formed as the first layer. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by CVD (chemical vapor deposition) was formed as the second layer. The film thickness of the SiN film of the second layer was 500 nm, which functioned as an interlayer insulating film. On the SiN film of the second layer, a comb-shaped pixel electrode (electrode width: 3 μm, electrode pitch: 6 μm, electrode height: 50 nm) formed by patterning an ITO film was disposed as the third layer.

[0194] The liquid crystal aligning agent filtered through a filter with a pore size of 0.2 μm was spin-coated on the surface of the above-mentioned glass substrate with electrodes to form a precoat, and then pre-cured on a hot plate at a temperature of 80 °C for 5 minutes and main-cured in a circulating oven at a temperature of 230 °C for 60 minutes. After the rubbing alignment treatment, a liquid crystal alignment film was obtained.

[0195] Using the above two substrates with liquid crystal alignment films as a set, a sealant was printed on the substrates, and another substrate was bonded so that the liquid crystal alignment film surfaces faced each other and the rubbing directions were anti-parallel, and the sealant was cured to produce an empty cell with a gap of 4 μm. Liquid crystal MLC-7028 (Merck & Co., Inc.) was injected into the empty cell by a reduced-pressure injection method, and the injection port was sealed. In order to remove the flow alignment during liquid crystal injection, it was heated at 120 °C and then slowly cooled to room temperature, and polarizers were bonded to both outer sides of the substrate to fabricate an FFS-driven liquid crystal cell.

[0196] (2) Evaluation of Abrasion Resistance

[0197] The liquid crystal alignment film was prepared by the method of step (1) above. The hardness of the liquid crystal alignment films prepared from liquid crystal alignment agents 1 to 18 was measured by the pencil method. The hardness of the polyimide film was measured by pressing a pencil with a known hardness on the liquid crystal alignment film. The pencil hardness tester consists of a metal block with a wheel on each side. There is a cylindrical hole in the middle of the metal block, which is inclined at an angle of (45 ± 1)°. With the help of a clip, the pencil can be fixed on the instrument and always remain in the same position. A spirit level is installed on the top of the instrument to ensure the level of the instrument during the test. The instrument is designed so that when the test state is in a horizontal position, the load applied by the pencil tip on the surface of the polyimide film should be (750 ± 10) g. Use a mechanical pencil sharpener to shave off 5 mm to 6 mm of the wood from each pencil, leaving the original, unscratched, smooth cylindrical pencil lead. Hold the pencil vertically, move the pencil back and forth on the sandpaper at a 90° angle to the sandpaper to flatten the tip of the pencil lead (into a right angle). Keep moving the pencil until a flat and smooth circular cross-section is obtained, and there are no chips and notches at the edge. Place the sample on a horizontal and stable surface, insert the pencil into the test instrument and fix it with a clip to keep the instrument level, and place the tip of the pencil on the surface of the polyimide film. Immediately after the tip of the pencil just touches the film, push the sample at a speed of 0.5 mm / s to 1 mm / s in the direction away from the operator for at least 7 mm. A magnifying glass with a magnification of 6 to 10 times can be used to determine the damage. If no scratch appears, repeat the test in an area where the test has not been carried out, and replace the pencil with a higher hardness until a scratch at least 3 mm long appears. If a scratch longer than 3 mm has already appeared, reduce the hardness of the pencil and repeat the test until a scratch longer than 3 mm no longer appears. The higher the hardness of the pencil used, the better the friction resistance of the alignment film. Those with >3H are set as "excellent", those between H and 3H are set as "good", and those <H are set as "poor". The evaluation results are shown in Table 1.

[0198] (3) Evaluation of liquid crystal alignment property

[0199] The FFS driving liquid crystal cells described in (1) above were respectively prepared from liquid crystal alignment agents 1 to 18, and a microscope was used to observe at a magnification of 50 times whether there were abnormal areas where the brightness changed when a voltage of 5 V was turned on and off. The case where no abnormal area was observed was set as the alignment property "excellent", and the case where an abnormal area was observed was set as "poor". The evaluation results are shown in Table 1.

[0200] (4) Evaluation of residual DC charge

[0201] The liquid crystal aligning agents 1 to 18 were respectively made into the FFS-driven liquid crystal cells described in the above (1). The FFS-driven liquid crystal cells were placed in an oven at 60°C, and a DC voltage of 5V was applied to the FFS-driven liquid crystal cells for 1 hour. After short-circuiting for 1 second, the voltage magnitude of the FFS-driven liquid crystal cells was measured, and the voltage value after 10 minutes was used as the residual DC charge of the FFS-driven liquid crystal cells. The test results are shown in Table 1.

[0202] (5) Evaluation of voltage holding ratio

[0203] The liquid crystal aligning agents 1 to 18 were respectively made into the FFS-driven liquid crystal cells described in the above (1). After applying a voltage of 5V to the manufactured FFS-driven liquid crystal cells with an application time of 60 microseconds and a span of 167 milliseconds, the voltage holding ratio 167 milliseconds after the application release was measured. The voltage holding ratio = voltage after 167 milliseconds / original applied voltage * 100%. During the measurement, the temperature of the FFS-driven liquid crystal cells was set to 25°C and 60°C respectively. The evaluation results are shown in Table 1.

[0204] Table 1

[0205]

[0206] It can be seen from the evaluation results in Table 1 that the liquid crystal alignment film formed by the liquid crystal aligning agent of the present invention not only has excellent rubbing resistance, but also has excellent liquid crystal alignment properties. The liquid crystal display element containing this liquid crystal alignment film has excellent electrical characteristics: it shows high voltage holding characteristics even in a high-temperature environment and has less charge accumulation. Therefore, the present invention can effectively solve the problems of reduced contrast caused by low voltage holding ratio in a high-temperature environment and image sticking caused by charge accumulation during long-term continuous operation. The present invention can be applied to display elements for large liquid crystal TVs that require strong rubbing treatment or mobile information terminals such as smart phones that display high-definition images.

Claims

1. A compound containing a nitrogen heterocycle, characterized in that: It has the structural formula shown below: In formula (B1), R1 is a C1-C5 alkyl group, a halomethylbenzyl group, a naphthylmethyl group, or a tert-butyl ester group; R2 is hydrogen or oxygen; and R3 is hydrogen or oxygen.

2. The nitrogen-containing heterocyclic polymer according to claim 1, wherein: The R1 is a propyl group, a trifluoromethylbenzyl group, a naphthylmethyl group or a tert-butyl ester group.

3. A method for preparing a nitrogen-containing heterocyclic polymer according to claim 1, characterized in that The following steps are involved: (1) 1,3,8-triazaspiro[4.5]decane-2,4-dione undergoes alkylation reaction with a chlorination reagent to obtain an intermediate; (2) The intermediate of step (1) is subjected to an alkylation reaction with p-aminobenzyl chloride or 4-aminobenzoyl chloride to obtain the nitrogen-containing heterocyclic polymer according to claim 1.

4. The preparation method according to claim 3, characterized in that: In step (1), the chlorination reagent includes 1-chloroalkane, halomethylbenzyl chloride, 1-chloromethylnaphthalene, and tert-butyl chloroformate; Preferably, in step (1), the chlorination reagent is added dropwise at a reaction temperature of 40-50°C; preferably, in step (2), p-aminobenzyl chloride or 4-aminobenzoyl chloride is added dropwise at a reaction temperature of 60-65°C.

5. A polyamic acid, characterized in that: Obtained by polycondensation of tetracarboxylic dianhydride and a diamine compound; the diamine compound includes diamine compound B1, which is at least one of the nitrogen-containing heterocyclic compounds according to claim 1; Preferably, the diamine compound B1 accounts for 10-50% of the total molar amount of the diamine compound; Preferably, the diamine compound B1 accounts for 10-30% of the total molar amount of the diamine compound.

6. The polyamic acid according to claim 5, characterized in that: The diamine compound further includes a diamine compound B2, wherein the diamine compound B2 is at least one of the following compounds (B2-1) to (B2-3); 7. The polyamic acid according to claim 5, wherein: The tetracarboxylic dianhydride includes tetracarboxylic dianhydride A1 and / or tetracarboxylic dianhydride A2, wherein the tetracarboxylic dianhydride A1 is at least one of the following compounds (A1-1) to (A1-4), and the tetracarboxylic dianhydride A2 is at least one of the following compounds (A2-1) to (A2-2); 8. A polyimide, characterized in that: The polyamic acid is obtained by imidization of the polyamic acid according to any one of claims 5 to 7.

9. A liquid crystal aligning agent, characterized in that: Comprising a polymer, wherein the polymer is at least one of the polyamic acid according to any one of claims 5 to 7 and the polyimide according to claim 8; Preferably, the liquid crystal alignment agent further comprises an organic solvent; Preferably, the organic solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-methylcaprolactam, N-methyl-2-pyrrolidone, γ-butyrolactone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol methyl ethyl ether, ethylene glycol dimethyl ether, and dimethyl sulfoxide; Preferably, the weight ratio of the polymer to the organic solvent is 1:10-100.

10. A liquid crystal alignment film and a liquid crystal display element, characterized in that: The liquid crystal alignment film is prepared from the liquid crystal alignment agent according to claim 9, and the liquid crystal display element includes the liquid crystal alignment film.

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