Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element

Abstract

The invention relates to a liquid crystal alignment agent, which comprises an oxygen-containing heterocyclic compound, and the oxygen-containing heterocyclic compound has a structure as shown in a formula (I), so that the cohesion of a liquid crystal alignment film prepared from the liquid crystal alignment agent can be improved, and the adhesive force between the liquid crystal alignment film and a substrate as well as between the liquid crystal alignment film and a frame adhesive can be improved. Therefore, the liquid crystal display element comprising the liquid crystal alignment film has better reliability.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of January 25, 2019, application number 201910072093.1, and invention name: "Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element". [Technical field]

[0002] The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element made therefrom, and in particular to a liquid crystal alignment agent containing an oxygen-containing heterocyclic compound, a liquid crystal alignment film and a liquid crystal display element made therefrom. [Background technology]

[0003] Liquid crystal display components have now generally replaced traditional cathode ray tube displays due to their thinness, power saving and high image quality, and are widely used in home and personal electronic products. In addition, with the diversification of information disclosure methods, the demand for public information displays (PID) in advertising, traffic information, education and corporate markets has also steadily increased.

[0004] In order to provide good image quality, liquid crystal display elements should have good electrical characteristics, such as low ion charge, high voltage retention rate, low residual DC, etc. When liquid crystal display elements are used in public information displays, since public information displays often use narrow frame specifications and are mostly set outdoors, in addition to good image quality, the demand for reliability is also high.

[0005] Therefore, how to improve the formulation of liquid crystal alignment agents to enhance the reliability of liquid crystal display elements and expand the application range of liquid crystal display elements, for example, to make them applicable not only to home and personal electronic products but also to public information displays, has become the goal of relevant industry players. [Summary of the invention]

[0006] An object of the present invention is to provide a liquid crystal alignment agent, wherein a liquid crystal alignment film prepared by the liquid crystal alignment agent has better cohesion and better adhesion to a substrate and a frame glue.

[0007] Another object of the present invention is to provide a liquid crystal alignment film having better cohesive force and better adhesion to the substrate and the frame glue, which is beneficial to improving the reliability of the liquid crystal display element.

[0008] Another object of the present invention is to provide a liquid crystal display element which has better reliability, is resistant to ultraviolet light, high temperature and high humidity, is conducive to narrow frame specifications and is suitable for outdoor use.

[0009] According to one embodiment of the present invention, a liquid crystal alignment agent is provided, comprising an oxygen-containing heterocyclic compound, wherein the oxygen-containing heterocyclic compound has a structure as shown in formula (I):

[0010]

[0011] Wherein X is a divalent linking group, each E is independently hydrogen, a monovalent organic group including an epoxy group, or a monovalent organic group including oxetane, and at least one of E is a monovalent organic group including an epoxy group or a monovalent organic group including oxetane, and the hydrogen of the naphthyl group may be substituted by fluorine, chlorine, bromine or a C1-C4 monovalent organic group.

[0012] According to another embodiment of the present invention, a liquid crystal alignment film is provided. The liquid crystal alignment film is formed by the liquid crystal alignment agent as described in the above paragraph.

[0013] According to another embodiment of the present invention, a liquid crystal display element is provided, comprising the liquid crystal alignment film described in the above paragraph.

[0014] In particular, the present invention is achieved by:

[0015] 1. A liquid crystal alignment agent, comprising:

[0016] An oxygen-containing heterocyclic compound having a structure as shown in formula (I):

[0017]

[0018] wherein X is a divalent linking group, each of the E's is independently a hydrogen, a monovalent organic group including an epoxy group, or a monovalent organic group including oxetane, and at least one of the E's is a monovalent organic group including an epoxy group or a monovalent organic group including oxetane, and the hydrogen of the naphthyl groups is optionally substituted by a fluorine, a chlorine, a bromine, or a C1-C4 monovalent organic group.

[0019] 2. The liquid crystal alignment agent as described in item 1, wherein X is a divalent linking group of C1 to C3.

[0020] 3. The liquid crystal alignment agent according to item 1, wherein at least one of the E has a structure as shown in formula (i), formula (ii) or formula (iii):

[0021]

[0022] In formula (i), R 1 , R 2 , R 3 , R 4 One of them is -GOJ-*, and the other three are each independently hydrogen or a C1-C3 monovalent alkyl group. In formula (ii), R 5 , R 6 , R 7, R 8 One of them is -GOJ-*, and the other three are each independently hydrogen or a C1-C3 monovalent alkyl group. In formula (iii), R 9 , R 10 One of them is -GOJ-*, and the other is hydrogen or a monovalent alkyl group of C1 to C3, wherein G is independently a divalent alkylene group of C1 to C3, J is independently a single bond or a divalent alkylene group of C1 to C3, and * is the bonding position to the naphthyl group in formula (I).

[0023] 4. The liquid crystal alignment agent according to item 1, wherein X is a divalent linking group of C1 to C3, and at least one of the E has a structure as shown in formula (i-1):

[0024]

[0025] Wherein * is the bonding position between the structure shown in formula (i-1) and the naphthyl group in formula (I).

[0026] 5. The liquid crystal alignment agent as described in item 1 further comprises a polymer, wherein the polymer is polyamic acid, polyimide or (amic acid / imide) copolymer.

[0027] 6. The liquid crystal alignment agent according to item 5, wherein the content of the oxygen-containing heterocyclic compound is 1 to 50 parts by weight, based on 100 parts by weight of the total weight of the polymer and the oxygen-containing heterocyclic compound.

[0028] 7. The liquid crystal alignment agent according to item 5, wherein the content of the oxygen-containing heterocyclic compound is 5 to 30 parts by weight, based on 100 parts by weight of the total weight of the polymer and the oxygen-containing heterocyclic compound.

[0029] 8. The liquid crystal alignment agent according to item 5, wherein the content of the oxygen-containing heterocyclic compound is 10 to 20 parts by weight, based on 100 parts by weight of the total weight of the polymer and the oxygen-containing heterocyclic compound.

[0030] 9. A liquid crystal alignment film, formed from the liquid crystal alignment agent according to any one of items 1 to 8.

[0031] 10. A liquid crystal display device comprising the liquid crystal alignment film according to item 9. [Specific implementation method]

[0032] In the present invention, if it is not specifically indicated whether a group is substituted, the group may represent a substituted or unsubstituted group. For example, "alkyl" may represent a substituted or unsubstituted alkyl. X " means that the main chain of the group has X carbon atoms.

[0033] In the present invention, the compound structure is sometimes represented by a skeleton formula, which may omit carbon atoms, hydrogen atoms, and carbon-hydrogen bonds. If the functional group is clearly drawn in the structural formula, the drawn one shall prevail.

[0034] In the present invention, the range expressed by "a value to another value" is a summary expression method that avoids listing all the values ​​in the range one by one in the specification. Therefore, the description of a specific numerical range covers any value in the numerical range and a smaller numerical range defined by any value in the numerical range, just as if the arbitrary value and the smaller numerical range were written in the specification. For example, the range of "0.1wt% to 1wt%" covers the range of "0.5wt% to 0.8wt%" regardless of whether other values ​​are listed in the specification.

[0035] <Liquid crystal alignment agent>

[0036] A liquid crystal alignment agent comprises an oxygen-containing heterocyclic compound, wherein the oxygen-containing heterocyclic compound has a structure as shown in formula (I):

[0037]

[0038] In formula (I), X is a divalent linking group, each E is independently hydrogen, a monovalent organic group containing an epoxy group, or a monovalent organic group containing oxetane, and at least one of E is a monovalent organic group containing an epoxy group or a monovalent organic group containing oxetane, and the hydrogen of the naphthyl group may be substituted by fluorine, chlorine, bromine or a C1-C4 monovalent organic group.

[0039] According to the aforementioned liquid crystal alignment agent, X may be a C1-C3 divalent linking group, for example, X may be, but is not limited to, a methylene group, an ethylene group, or a propylene group.

[0040] According to the aforementioned liquid crystal alignment agent, at least one of the four E in formula (I) may have a structure as shown in formula (i), formula (ii) or formula (iii):

[0041]

[0042] In formula (i), R 1 , R 2 , R 3 , R 4 One of them is -GOJ-*, the other three are independently hydrogen or a C1-C3 monovalent alkyl group, G can be a C1-C3 divalent alkylene group, J can be a single bond or a C1-C3 divalent alkylene group, and * is the bonding position with the naphthyl group in formula (I). In other words, -GOJ-* is connected to the epoxy group in formula (i) by G.

[0043] In formula (ii), R 5 , R 6 , R 7 , R 8 One of them is -GOJ-*, the other three are independently hydrogen or a C1-C3 monovalent alkyl group, G can be a C1-C3 divalent alkylene group, J can be a single bond or a C1-C3 divalent alkylene group, and * is the bonding position with the naphthyl group in formula (I). In other words, -GOJ-* is connected to the six-membered ring in formula (ii) by G.

[0044] In formula (iii), R 9 , R 10 One of them is -GOJ-*, the other is hydrogen or a C1-C3 monovalent alkyl group, G can be a C1-C3 divalent alkylene group, J can be a single bond or a C1-C3 divalent alkylene group, and * is the bonding position with the naphthyl group in formula (I). In other words, -GOJ-* is connected to the oxetane group in formula (iii) by G.

[0045] In formula (i) to formula (iii), J may be the same or different, and G may be the same or different.

[0046] According to the aforementioned liquid crystal alignment agent, X in formula (I) may be a divalent linking group of C1 to C3, and at least one of the four E's has a structure as shown in formula (i-1):

[0047]

[0048] In formula (i-1), * represents the bonding position between the structure represented by formula (i-1) and the naphthyl group in formula (I).

[0049] For example, the oxygen-containing heterocyclic compound of formula (I) may have a structure as shown in, but not limited to, formula (I-1), formula (I-2), formula (I-3), formula (I-4) or formula (I-5):

[0050]

[0051] According to the aforementioned liquid crystal alignment agent, a polymer may be further included as an alignment polymer, and the polymer may be polyamic acid, polyimide, (amic acid / imide) copolymer, polyamic acid ester, polyester, polyamide, cellulose derivative, polyacetal, polystyrene derivative, poly(styrene-phenylmaleimide) derivative, poly(meth)acrylate, etc. The aforementioned polymers may be used alone or simultaneously.

[0052] According to the aforementioned liquid crystal alignment agent, based on the total weight of the polymer and the oxygen-containing heterocyclic compound as 100 parts by weight, the content of the oxygen-containing heterocyclic compound may be 1 part by weight to 50 parts by weight, or, the content of the oxygen-containing heterocyclic compound may be 5 parts by weight to 30 parts by weight, or, the content of the oxygen-containing heterocyclic compound may be 10 parts by weight to 20 parts by weight.

[0053] According to the aforementioned liquid crystal alignment agent, an organosilicon (oxygen) alkane compound and an oxygen-containing heterocyclic compound different from the oxygen-containing heterocyclic compound of formula (I) may be further included. Examples of the aforementioned organosilicon (oxygen) alkane compound may be, but are not limited to, aminopropyl trimethoxysilane, aminopropyl triethyl silane, vinyl methyl silane, N-(2-aminoethyl)-3-aminopropyl methyl dimethoxy silane, N-(2-aminoethyl)-3-aminopropyl trimethoxy silane, vinyl triethoxy silane, 3-methacryloxypropyl trimethoxy silane, 3-glycidoxypropyl trimethoxy silane, 3-glycidoxypropyl methyl dimethoxy silane, 2-(3,4- Epoxycyclohexyl)ethyl trimethoxysilane, 3-ureidopropyl trimethoxysilane, 3-ureidopropyl triethoxysilane, N-ethoxycarbonyl-3-aminopropyl trimethoxysilane, N-ethoxycarbonyl-3-aminopropyl triethoxyamine silane, N-triethoxysilylpropyl triethylenetriamine, N-trimethoxysilylpropyl triethylenetriamine, N-bis(oxyethylene)-3-aminopropyl trimethoxysilane, N-bis(oxyethylene)-3-aminopropyl triethylsilane.

[0054] According to the aforementioned liquid crystal alignment agent, a solvent may be further included. The aforementioned solvent may be, but is not limited to, N-methyl-2-pyrrolidinone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, dimethyl sulfoxide, γ-butyrolactone, γ-butyrolactam, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether or ethylene glycol butyl ether (BC). The above solvents may be used alone or in combination.

[0055] <Liquid crystal alignment film>

[0056] A liquid crystal alignment film is formed by the liquid crystal alignment agent mentioned above. Specifically, the liquid crystal alignment film can be made by coating the liquid crystal alignment agent mentioned above on a substrate.

[0057] Generally speaking, the film thickness of the liquid crystal alignment film formed by the above method is preferably 0.005 μm to 0.5 μm. The thickness of the liquid crystal alignment film is usually adjusted according to the viscosity of the liquid crystal alignment agent and the coating method of the liquid crystal alignment agent. In addition, the thickness of the liquid crystal alignment film can be measured using common film thickness measuring devices such as a step difference meter and an ellipsometer.

[0058] The substrate may be, but is not limited to, a plastic substrate, a glass epoxy resin substrate, a glass substrate, a ceramic substrate or a metal substrate, preferably one that can withstand the processing conditions described below.

[0059] The material of the plastic substrate may be, but is not limited to, a thermosetting resin (such as epoxy resin, phenol resin, polyimide resin, polyester resin, etc.) or a thermoplastic resin (such as phenoxy resin, polyether sulfone, polysulfone, polyphenylene sulfone, etc.).

[0060] The material of the glass substrate may be, but is not limited to, glass, potassium glass, borosilicate glass, quartz glass, aluminosilicate glass or lead glass.

[0061] The material of the ceramic substrate may be, but is not limited to, aluminum oxide, aluminum nitride, zirconium oxide, silicon, silicon nitride or silicon carbide.

[0062] The material of the metal substrate may be, but is not limited to, aluminum, zinc or copper.

[0063] In addition, the substrate may also be a structure formed by laminating two or more layers of the above-mentioned plastic substrate, glass substrate, ceramic substrate, metal substrate, etc. Of course, it may also be a substrate having a patterned transparent conductive film. Preferably, the substrate may be a glass substrate having a patterned transparent conductive film.

[0064] The method of coating the liquid crystal alignment agent on the substrate may be, but is not limited to, a roller coating method (roller coating method), a spin coating method or a spray printing method.

[0065] After the liquid crystal alignment agent is coated on the substrate, it can be fired to form a thin film. The firing method is, for example, heating and baking. The heating and baking method can be, but is not limited to, a method of heating in an oven or an infrared furnace, or a method of heating on a hot plate. By heating and baking, the solvent in the liquid crystal alignment agent can be removed. If the liquid crystal alignment agent contains polyamic acid, it can also promote a dehydration ring-closing reaction. In this embodiment, the heating and baking temperature is 80°C to 300°C, preferably 200°C to 250°C.

[0066] <Liquid Crystal Display Element>

[0067] A liquid crystal display element comprises the aforementioned liquid crystal alignment film. The liquid crystal display element can be manufactured by the following method. First, the aforementioned liquid crystal alignment agent is applied to a substrate to obtain a liquid crystal alignment film. The details are as described above and will not be repeated here. Next, a roller wound with nylon or cotton fiber cloth can be used for directional rubbing so that the liquid crystal alignment film can provide liquid crystal molecular alignment. Afterwards, a frame glue is applied on a substrate having the aforementioned liquid crystal alignment film, and a spacer is sprayed on another substrate having the aforementioned liquid crystal alignment film. Then, the two substrates having the aforementioned liquid crystal alignment film are combined in such a way that the film brushing directions are perpendicular or parallel to each other, and liquid crystal is injected into the gap therebetween, and then the injection hole is sealed to preliminarily form a liquid crystal display element. As for the subsequent process of completing the liquid crystal display element, it is well known to those familiar with this technology and will not be repeated here.

[0068] The aforementioned sealant may include a photo initator, epoxy, a catalyst, and an arylic resin, etc. The sealant that can be used includes but is not limited to 723K1 (produced by Synergy Chemical).

[0069] The present invention will be described in more detail below with examples. As long as the materials used, dosages, ratios, processing details and processing procedures etc. of the following examples are appropriately changed without exceeding the scope of the present invention. Therefore, the embodiments of the present invention are only illustrative and should not be used to make a restrictive interpretation of the present invention.

[0070] <Preparation of Examples / Comparative Examples>

[0071] The liquid crystal alignment agent of Example 1: The oxygen-containing heterocyclic compound of formula (I-1) is added to a polyamic acid solution (trade name DA-9003, produced by Daxing Materials), and diluted with a mixed solvent of N-methyl-2-pyrrolidone (NMP) and ethylene glycol butyl ether (BC) in a weight ratio of 1:1 to form a liquid crystal alignment agent with a solid content of 6.5wt%, wherein the addition ratio of the oxygen-containing heterocyclic compound of formula (I-1) is as follows: the total weight of the oxygen-containing heterocyclic compound of formula (I-1) and polyamic acid is 100 parts by weight, and the content of the oxygen-containing heterocyclic compound of formula (I-1) is 5 parts by weight (hereinafter referred to as 5wt%, equivalent to the addition ratio in Table 1).

[0072] The liquid crystal alignment film of Example 1: The prepared liquid crystal alignment agent was sprayed onto a glass substrate with an indium tin oxide (ITO) transparent electrode by using an inkjet printer (Inkjet Printing, IJP; model: DMP-2831; manufacturer: FUJIFILM), and was pre-baked on a hot plate at 85°C for 135 seconds, and then moved to an oven at 230°C for 30 minutes to form a thickness of 1.5 %. liquid crystal alignment film.

[0073] The liquid crystal display element of Example 1: A pair of glass substrates formed with the above-mentioned liquid crystal alignment films are combined with liquid crystal (Merck, model LCT12516) by the existing method to obtain a liquid crystal display element containing a pair of liquid crystal alignment films, a liquid crystal layer sandwiched between the pair of liquid crystal alignment films, and a pair of electrode layers respectively arranged on the side of the pair of liquid crystal alignment films away from the liquid crystal layer.

[0074] Examples 2 to 4 and Comparative Examples 1 to 17: The amount of the oxygen-containing heterocyclic compound of formula (I-1) in the liquid crystal alignment agent raw material of Example 1 is replaced, or replaced with additional compounds of different types and amounts, as shown in Table 1. The remaining steps are the same, and the liquid crystal alignment agents, liquid crystal alignment films and liquid crystal display elements of Examples 2 to 4 and Comparative Examples 1 to 17 can be obtained.

[0075]

[0076] There is no added compound in Comparative Example 1 in Table 1, that is, the liquid crystal alignment agent in Comparative Example 1 is a liquid crystal alignment agent with a solid content of 6.5wt% by directly diluting the polyamic acid solution (trade name DA-9003, produced by Daxing Materials) with a mixed solvent of NMP and BC in a weight ratio of 1:1. The structures of the added compounds other than formula (I-1) in Table 1 are shown in Table 2. In Table 2, the epoxy equivalent weight (EEW) of HP-7200H is 272 to 284 g / eq., and the viscosity at 150°C is 2.0 to 6.0 dPa·s. L in EXA-4816 1 It has an aliphatic skeleton (here, a long chain hydrocarbon chain), an EEW of 403 g / eq., and a viscosity of 1,400,000 mPa·s at 25°C. 2 It has a flexible skeleton and a low-polarity binding group, with an EEW of 350 g / eq. and a viscosity of 100,000 mPa·s at 25°C.

[0077]

[0078] <Property Measurement and Evaluation Methods of Examples / Comparative Examples>

[0079] Adhesion test, the measurement method is as follows: the liquid crystal alignment agents of Examples 1 to 4 and Comparative Examples 1 to 17 are coated on an ITO glass substrate with a thickness of 0.5 mm and an area of ​​10 cm×10 cm by a coater, and pre-baked on a hot plate at 120° C. for 135 seconds, and then moved to an oven at 230° C. for 30 minutes to form a thickness of Afterwards, the ITO glass substrate coated with the liquid crystal alignment film was cut into rectangular ITO glass substrates with an area of ​​2.5 cm × 1.5 cm using a glass cutter, and 723K1 sealant was applied between two rectangular ITO glass substrates with an area of ​​2.5 cm × 1.5 cm using a sealant machine (model ML-808FX, manufacturer MUSASHI), and pressed with a 1.0 kg weight for 1 minute and left to stand for 1 hour, and then irradiated with ultraviolet light with a wavelength of 365 nm, a total of 3000 mJ / cm 2 The light intensity was accumulated and then moved to a 120°C oven for 1 minute to obtain a tensile test piece with a diameter of 5 mm. The value of the tensile test piece when it broke was evaluated using a universal tensile test machine (model EZ-L, manufacturer SHIMADZU) and used as the adhesion value. When the adhesion is greater than or equal to 10N, it can meet the requirements.

[0080] The liquid crystal display elements of Examples 1 to 4 and Comparative Examples 1 to 17 were irradiated with ultraviolet light having a wavelength of 365 nm and a total of 8520 mJ / cm 2 The amount of light is integrated to make the acrylic components in the liquid crystal react completely, and then the pre-tilt angle (PTA), ion density (ID), voltage holding ratio (VHR), residual direct current (RDC), and transmittance to time (TT) are measured.

[0081] After that, the samples were irradiated with 365 nm ultraviolet light (total 8520 mJ / cm 2 The integrated light quantity) and the 121℃ / 100% / 6h high temperature and high humidity deterioration test (which means placing it in an environment with a temperature of 121℃ and a humidity of 100% for 6 hours), and then measuring its ion density and voltage holding rate.

[0082] PTA measurement method: The PTA of the liquid crystal display element of the embodiment / comparative example is evaluated with different phase differences using a pretilt angle meter (model: Autronic TBA-107). If the PTA falls within 90±2 degrees, it indicates that the liquid crystal display element has good vertical alignment capability.

[0083] ID measurement method: The ion density of the liquid crystal display element of the embodiment / comparison example is measured using a liquid crystal material parameter tester (model ALCT-IV1, manufacturer: Instec Inc). The liquid crystal material parameter tester is used to apply a triangular waveform to measure the ion density of the liquid crystal display element of the embodiment / comparison example placed in a 60°C oven. When ID is less than or equal to 5000pC, the requirement can be met.

[0084] Measurement method of VHR-1V: Pass an alternating current with a voltage of 1V and a frequency of 0.6Hz through the liquid crystal display element of the embodiment / comparative example, and measure the voltage attenuation rate in each half cycle by area calculation. When VHR-1V is greater than or equal to 85%, the requirement can be met.

[0085] Measurement method of VHR-5V: Pass an alternating current of 5V and 0.6Hz through the liquid crystal display element of the embodiment / comparative example, and measure the voltage attenuation rate in each half cycle by area calculation. When VHR-5V is greater than or equal to 95%, the requirement can be met.

[0086] RDC measurement method: Place the liquid crystal display element of the embodiment / comparative example in a 60°C oven, apply a DC voltage of 5V-1h, discharge for 1 second, and record the residual DC voltage value (as the RDC value) after 10 minutes. When RDC is less than or equal to 100mV, the requirement can be met.

[0087] TT evaluation method: The liquid crystal display element of the embodiment / comparative example is driven by an AC power of 3.5V and 60Hz, and the transmittance (T1) is recorded after 3 minutes. Then, it is driven by a DC power of 15V for 30 minutes, and then switched back to an AC power of 3.5V and 60Hz. The transmittance (T2) is recorded after 15 minutes. [|T2-T1| / T1]×100% is taken as TT. When TT is less than or equal to 10%, the requirement can be met.

[0088] <Measurement Results of Properties of Examples / Comparative Examples>

[0089] Table 3 shows the adhesion measurement results of the liquid crystal alignment films of Examples 1 to 4 and Comparative Examples 1 to 17, as well as the measurement results of PTA, ID, VHR-1V, VHR-5V, RDC and TT of the liquid crystal display elements of Examples 1 to 4 and Comparative Examples 1 to 17 after the first irradiation of ultraviolet light.

[0090]

[0091]

[0092] Table 4 shows the measurement results of ID, VHR-1V, and VHR-5V of the liquid crystal display elements of Examples 1 to 4 and Comparative Examples 1 to 17 after the second ultraviolet light irradiation and the 121°C / 100% / 6h high temperature and high humidity deterioration test, as well as the difference between the measurement results of ID, VHR-1V, and VHR-5V after the first ultraviolet light irradiation and the second ultraviolet light irradiation and the 121°C / 100% / 6h high temperature and high humidity deterioration test.

[0093]

[0094] As shown in Table 3, the adhesion of the liquid crystal alignment films of Examples 1 to 4 is greater than or equal to 10N. It can be seen that the cohesive force and adhesion to the substrate and the frame glue of the liquid crystal alignment film according to the present invention are improved, and the structural tensile force of the overall component of the tensile test piece (structure is ITO / liquid crystal alignment film / frame glue / liquid crystal alignment film / ITO) can be enhanced. The PTA of the liquid crystal display elements of Examples 1 to 4 is 90 degrees, indicating that the liquid crystal display elements according to the present invention have good vertical alignment capabilities. After the first exposure to ultraviolet light, the liquid crystal display elements of Examples 1 to 4 can simultaneously meet the five major requirements of ID less than or equal to 5000pC, VHR-1V greater than or equal to 85%, VHR-5V greater than or equal to 95%, RDC less than or equal to 100mV and TT less than or equal to 10%, indicating that the liquid crystal display elements according to the present invention have electrical characteristics that meet the requirements and can provide excellent image quality.

[0095] It can be seen from Table 4 that after the second UV irradiation and the 121°C / 100% / 6h high temperature and high humidity deterioration test, the liquid crystal display elements of Examples 1 to 4 can still meet the requirements of ID less than or equal to 5000pC, VHR-1V greater than or equal to 85%, and VHR-5V greater than or equal to 95%, etc., indicating that the liquid crystal display element according to the present invention has excellent reliability, is resistant to UV light, and is resistant to high temperature and high humidity. After being exposed to UV light and harsh environments such as high temperature and high humidity, it can still provide electrical characteristics that meet the requirements and can still provide excellent image quality.

[0096] In addition, it can be seen from the difference values ​​in Table 4 that, compared with Comparative Examples 1 to 17, in the liquid crystal display elements of Examples 1 to 4, the difference range of ID is 216 to 1447 pC, the difference range of VHR-1V is -3 to 3%, and the difference range of VHR-5V is -2 to 0%, which further shows that the liquid crystal display element according to the present invention does not change much in the values ​​of ID, VHR-1V and VHR-5V before and after being exposed to ultraviolet light and a harsh environment of high temperature and high humidity, has excellent reliability, can provide stable electrical characteristics, and has great potential for application in narrow frame specifications and outdoor installation.

[0097] Although the present invention has been disclosed as above in the form of an implementation method, it is not intended to limit the present invention. Any person skilled in the art should be able to make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the attached claims.

Claims

1. A liquid crystal alignment agent, comprising: An oxygen-containing heterocyclic compound having a structure as shown in any one of formula (I-1), formula (I-2), formula (I-3), formula (I-4) and formula (I-5): wherein the hydrogen of the naphthyl group is optionally substituted by fluorine, chlorine, bromine or a C1-C4 monovalent organic group; A polymer, wherein the polymer is a polyamic acid, a polyimide, or a copolymer of an amic acid and an imide; and Solvents, Wherein, based on 100 parts by weight of the total weight of the polymer and the oxygen-containing heterocyclic compound, the content of the oxygen-containing heterocyclic compound is 5 parts by weight to 15 parts by weight.

2. The liquid crystal alignment agent as claimed in claim 1, wherein the solvent is N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, dimethyl sulfoxide, γ-butyrolactone, γ-butyrolactam, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol butyl ether or any combination thereof. 3 . The liquid crystal alignment agent according to claim 1 , wherein the content of the oxygen-containing heterocyclic compound is 10 to 15 parts by weight based on 100 parts by weight of the total weight of the polymer and the oxygen-containing heterocyclic compound. 4 . A liquid crystal alignment film, formed by the liquid crystal alignment agent according to claim 1 . 5 . A liquid crystal display element, comprising the liquid crystal alignment film according to claim 4 .

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