Flat alignment composition and display panel

Abstract

The invention relates to a flat alignment composition and a display panel. The flat alignment composition comprises a copolymer, and the copolymer has a structural formula as shown in a formula (1), b is selected from a crosslinking group; n is any integer selected from 30 to 500; the copolymer in the flat alignment composition provided by the invention contains a mesogenic structure, so that the flat alignment layer has an alignment effect; meanwhile, the copolymer also contains a crosslinking group, so that the crosslinking degree after film formation is improved, the heat resistance and the stability of the flat alignment layer are improved, a film layer with higher flatness is favorably formed, and the flat alignment layer can have a flattening effect; therefore, the flat alignment layer can simultaneously have the functions of a flat layer and an alignment layer, the process can be simplified, and the cost can be reduced.

Description

Technical Field

[0001] This application relates to the field of display technology, and more particularly to a planar alignment composition and a display panel. Background Technology

[0002] A liquid crystal display (LCD) panel is generally composed of a thin film transistor (TFT) substrate, a color filter (CF) substrate, and a liquid crystal layer. The TFT substrate provides switching signals and data signals, the CF substrate provides colorization, and the liquid crystal layer controls the display brightness according to the liquid crystal deflection angle.

[0003] Currently, a liquid crystal alignment layer is needed to anchor the liquid crystal in its initial orientation, and commonly used materials for this layer are polyimide or polyamic acid. Furthermore, to avoid uneven film thickness on one side of the color filter substrate due to the step difference created by the color filter layer, which could lead to uneven display, a planarization film needs to be applied to the color filter substrate before coating the liquid crystal alignment layer. This further complicates the manufacturing process of the liquid crystal display panel and increases its cost. Summary of the Invention

[0004] This application provides a planar alignment composition and a display panel, which can obtain a planar alignment layer that has both planarization and alignment functions, simplifying the process and reducing costs.

[0005] This application provides a planar alignment composition comprising a copolymer having a structural formula as shown in formula (1):

[0006]

[0007] Among them, A contains a mesocrystalline structure;

[0008] B is selected from crosslinking groups;

[0009] n is any integer between 30 and 500.

[0010] In one embodiment of this application, A is selected from at least one of biphenyl and phenoxy.

[0011] In one embodiment of this application, B is selected from at least one of epoxy group, hydroxyl group, carboxyl group and glycidyl group.

[0012] In one embodiment of this application, the copolymer is selected from at least one of the following compounds:

[0013]

[0014] In one embodiment of this application, the planar alignment composition further includes a functional component comprising a crosslinking agent and a solvent, wherein the crosslinking agent contains at least one hydroxyl group.

[0015] In one embodiment of this application, the copolymer accounts for 70% to 90% of the mass percentage of the planar alignment composition;

[0016] The crosslinking agent comprises, by mass, 0.1% to 10% of the planar alignment composition.

[0017] The solvent accounts for 10% to 30% of the mass of the planar alignment composition.

[0018] In accordance with the above-mentioned objectives of this application, embodiments of this application also provide a display panel, the display panel comprising:

[0019] First substrate;

[0020] A planar alignment layer is disposed on the first substrate, and the planar alignment layer is prepared using the planar alignment composition.

[0021] In one embodiment of this application, the planar alignment layer contains a structure as shown in formula (2);

[0022]

[0023] R is obtained from B through a cross-linking reaction;

[0024] * indicates a connection point.

[0025] In one embodiment of this application, the display panel further includes:

[0026] A color filter layer is disposed on the first substrate, and the planar alignment layer is disposed on the side of the color filter layer away from the first substrate and covers the color filter layer;

[0027] A liquid crystal layer is disposed on the side of the planar alignment layer away from the first substrate;

[0028] The planar alignment layer has a first step on the side of its surface away from the first substrate, and the color filter layer has a second step on the side of its surface away from the first substrate. The first step is smaller than the second step. The planar alignment layer is configured such that the liquid crystal molecules in the liquid crystal layer have an initial alignment direction.

[0029] In one embodiment of this application, the display panel further includes:

[0030] The second substrate is disposed on the side of the liquid crystal layer away from the planar alignment layer;

[0031] An alignment layer is disposed between the second substrate and the liquid crystal layer;

[0032] The material of the opposing alignment layer includes polyimide.

[0033] In one embodiment of this application, the display panel further includes:

[0034] A pixel electrode layer is disposed between the second substrate and the liquid crystal layer, and the pixel electrode layer is located on one side of the opposing alignment layer along the thickness direction of the display panel;

[0035] A common electrode layer is disposed between the second substrate and the liquid crystal layer, and the common electrode layer is located on one side of the opposing alignment layer along the thickness direction of the display panel;

[0036] The pixel electrode layer and the common electrode layer are configured to jointly form a horizontal electric field.

[0037] In one embodiment of this application, the planar alignment layer is in contact with the color filter layer.

[0038] This application provides a planar alignment composition and a display panel. The planar alignment composition is used to prepare a planar alignment layer in a display panel. The copolymer in the planar alignment composition contains a mesocrystalline structure, which enables the planar alignment layer to have an alignment function. Simultaneously, the copolymer also contains crosslinking groups, increasing the degree of crosslinking after film formation, improving the heat resistance and stability of the planar alignment layer, and facilitating the formation of a film layer with higher flatness. This allows the planar alignment layer to have a planarization function. Therefore, the planar alignment layer can simultaneously function as both a planarization layer and an alignment layer, simplifying the process and reducing costs.

[0039] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0042] Figure 1 This is a schematic diagram of the structure of a display panel in one embodiment;

[0043] Figure 2 This is a schematic diagram of the network structure formed by the copolymer and crosslinking agent provided in the embodiments of this application;

[0044] Figure 3 The NMR spectrum of copolymer M1 in Example 1 provided for the embodiments of this application;

[0045] Figure 4 The NMR spectrum of copolymer M2 in Example 2 of this application is provided for the purpose of providing embodiments of the present application;

[0046] Figure 5 This is a schematic diagram of a display panel provided in an embodiment of this application.

[0047] Explanation of reference numerals in the attached figures:

[0048] 1. Color filter substrate; 2. Array substrate; 3. Liquid crystal; 4. Color filter layer; 5. Planarization layer; 6. First alignment layer; 7. Second alignment layer;

[0049] 11. First substrate; 12. Second substrate; 20. Color filter layer; 21. Black matrix; 22. Color resist block; 31. Planar alignment layer; 32. Opposed alignment layer; 40. Liquid crystal layer. Detailed Implementation

[0050] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0051] Please refer to Figure 1 Currently, the display panel includes a color filter substrate 1 and an array substrate 2 disposed opposite to each other, and a liquid crystal 3 located between the color filter substrate 1 and the array substrate 2. The display panel also includes a color filter layer 4 disposed between the liquid crystal 3 and the color filter substrate 1. Since the color filter layer 4 is provided with a black matrix and color resists of different colors, the surface flatness of the side of the color filter layer 4 away from the color filter substrate 1 is poor, and it has a large step difference. Therefore, the display panel also includes a planarization layer 5 disposed on the side of the color filter layer 4 away from the color filter substrate 1 to improve the flatness of the color filter layer 4. Furthermore, in order to provide an initial alignment direction for the liquid crystal 3, the display panel also includes a first alignment layer 6 disposed on the side of the planarization layer 5 away from the color filter substrate 1 and a second alignment layer 7 disposed between the array substrate 2 and the liquid crystal 3. The number of film layers is large, which leads to complex processes and increased costs.

[0052] This application provides a planar alignment composition comprising a copolymer having a structural formula as shown in formula (1):

[0053]

[0054] Among them, A contains a mesocrystalline structure;

[0055] B is selected from crosslinking groups;

[0056] n is any integer between 30 and 500.

[0057] In the implementation and application process, this application provides a planar alignment composition to prepare a planar alignment layer in the display panel. The copolymer in the planar alignment composition contains a mesocrystalline structure, which enables the planar alignment layer to have an alignment function. At the same time, the copolymer also contains crosslinking groups, which increases the degree of crosslinking after film formation, improves the heat resistance and stability of the planar alignment layer, and is conducive to forming a film layer with higher flatness, thus enabling the planar alignment layer to have a planarization function. Therefore, the planar alignment layer can simultaneously have the functions of a planarization layer and an alignment layer, which can simplify the process and reduce costs.

[0058] Specifically, this application provides a planar alignment composition comprising a copolymer and a functional component, wherein the copolymer has a structural formula as shown in formula (1):

[0059]

[0060] Among them, A contains a mesocrystalline structure;

[0061] B is selected from crosslinking groups;

[0062] n is any integer between 30 and 500.

[0063] In some embodiments, A may contain at least one benzene ring; for example, A is selected from at least one of biphenyl and phenoxy groups.

[0064] In some embodiments, B contains crosslinkable groups, for example, B may contain unsaturated groups, for example, B may be selected from at least one of epoxy, hydroxyl, carboxyl and glycidyl groups.

[0065] Furthermore, in some embodiments, A contains both an oxygen atom and a biphenyl group; for example, A can be a biphenyl group; B is selected from epoxy or carboxyl groups.

[0066] In some embodiments, the copolymer is selected from at least one of the following compounds:

[0067]

[0068] Furthermore, in some embodiments, the functional component includes a crosslinking agent containing at least one hydroxyl group; subsequently, the copolymer can further undergo a crosslinking reaction with the crosslinking agent to form such a crosslinking copolymer. Figure 2 The network structure shown can be further improved by linking the crosslinking agent WA between adjacent segments of the copolymer WB to increase the degree of crosslinking and improve the flatness of the planar alignment layer made from the planar alignment composition.

[0069] For example, copolymers are Crosslinking agent is The two can then be cross-linked to obtain a network structure; wherein, considering the strength of the resulting coating, the operability during coating formation, and the uniformity of the coating, n is selected from any integer from 30 to 500; and the weight-average molecular weight that can be determined by GPC (Gel Permeation Chromatography) is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000.

[0070] In some embodiments, the crosslinking agent may be selected from at least one of the following compounds:

[0071]

[0072] In some embodiments, the functional component further includes a solvent, and the solvent may be selected from propylene glycol monomethyl ether acetate.

[0073] In some embodiments, the copolymer constitutes 70% to 90% of the mass of the planar alignment composition; for example, it may be 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or 90%.

[0074] In some embodiments, the crosslinking agent may be present in the planar alignment composition at a mass percentage ranging from 0.1% to 10%; for example, it may be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0075] In some embodiments, the solvent comprises 10% to 30% by mass in the planar alignment composition, for example, 10%, 15%, 20%, 25% or 30%.

[0076] Furthermore, embodiments of this application also provide a method for preparing the above-mentioned copolymers, and the preparation methods of copolymers M1 and M2 are described as examples.

[0077] Copolymer M1 is:

[0078]

[0079] The synthesis process of copolymer M1 is as follows:

[0080]

[0081] Specifically, under a nitrogen atmosphere, NBS (4.65 g, 26.1 mmol) and AgNO3 (0.402 g, 2.36 mmol) were added to 4-methoxy-4'-methyl-1,1'-biphenyl (5.00 g, 22.6 mmol). A mixed solvent of H2O / acetonitrile (volume ratio 1:5, 113 g) was added after oxygen was degassed by nitrogen blowing. The mixture was further subjected to three cycles of oxygen degassing and nitrogen repressurization under reduced pressure to ensure thorough oxygen removal. The reaction was then initiated under 250 W UV irradiation at room temperature. After 12 hours of reaction, the mixture was transferred to a post-processing unit. Excess NBS was quenched by adding 10% sodium sulfite solution (80 g), and the mixture was extracted with dichloromethane. The organic layers were combined. The mixture was washed sequentially with saturated sodium bicarbonate solution (80 g) and saturated sodium chloride solution (80 g), dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated to obtain a pale yellow solid. The solid was recrystallized from a hexane-ethyl acetate mixture (5:1, v / v) to give a white solid M-D1 (4.05 g, 18.6 mmol, yield: 82.3%). The target product was analyzed using a Fourier transform superconducting nuclear magnetic resonance (FT-NMR) apparatus, "AVANCE III" (BRUKER), at 500 MHz, with deuterated N,N-dimethyl sulfoxide ([D6]-DMSO) as the solvent and tetramethylsilane (TMS) as the standard. The results are shown below. Based on these results, the obtained solid was confirmed to be the target M-D1.

[0082] 1H-NMR (500MHz, [D6]-DMSO): δ (ppm) = 7.37 (d, 2H), 7.36 (d, 2H), 7.12 (t, 2H), 6.83 (d, 2H), 6.18 (m, 2H), 2.35 (s, 3H), 2.0 (s, 1H).

[0083] Dichloromethane (88 g) was added to M-D1 (3.80 g, 17.5 mmol), and the mixture was cooled to 0 °C in an ice bath. Triethylamine (2.66 g, 26.3 mmol) was added, and the mixture was stirred for 10 minutes. Then, a dichloromethane solution (18 g) of methacryloyl chloride (2.30 g, 21.9 mmol) was slowly added dropwise. After the addition was complete, the mixture was heated to room temperature and the reaction was continued for 4 hours. After the reaction was stopped, the mixture was transferred to a post-processing unit. The reaction solution was neutralized with 1N hydrochloric acid (50 g), and the organic layer obtained by liquid-liquid chromatography was washed again with 1N hydrochloric acid (50 g). The organic layer was obtained by liquid-liquid chromatography. The organic layer was washed, dried, and filtered to obtain a pale yellow oil. The oil was purified by column chromatography using a petroleum ether:ethyl acetate ratio of 15:1 (v / v) to obtain a colorless liquid M-D2 (4.32 g, 14.3 mmol, yield: 81.7%). The 1H NMR spectrum of the product is shown below. Based on this result, the obtained solid was confirmed to be the target M-D2.

[0084] 1H-NMR (500MHz, [D6]-DMSO): δ (ppm) = 7.37 (d, 2H), 7.36 (d, 2H), 7.12 (t, 2H), 6.83 (d, 2H), 6.80 (m, 2H), 6.15 (d, 1H), 5.58 (d, 1H), 2.35 (s, 3H), 1.93 (s, 3H).

[0085] Under a nitrogen atmosphere, NBS (2.72 g, 15.3 mmol) was added to M-D2, along with a H2O / THF mixed solvent (volume ratio 1:4, 66 g) degassed by nitrogen blowing and NaOH (0.528 g, 13.2 mmol). The reaction was further subjected to three cycles of oxygen degassing and nitrogen repressurization under reduced pressure to ensure thorough oxygen removal. The reaction was then initiated at 50°C under 300 W high-pressure mercury lamp irradiation. After the reaction was complete, the reaction solution was cooled to room temperature, and the pH was adjusted to neutral with 1 N hydrochloric acid. Extraction was performed with ethyl acetate, and the organic layer was obtained by separation. The organic layer was washed, dried, filtered, and purified to obtain M-D3 (3.58 g, 11.0 mmol, yield: 83.3%). The 1H NMR spectrum of the product is shown below. Based on these results, the obtained solid was confirmed as the target M-D3.

[0086] 1H-NMR (500MHz, [D6]-DMSO): δ (ppm) = 7.41 (d, 2H), 7.37 (d, 2H), 7.25 (t, 2H), 6.83 ( d, 2H), 6.80 (m, 2H), 6.15 (d, 1H), 5.58 (d, 1H), 4.79 (m, 2H), 2.0 (s, 1H), 1.93 (s, 3H).

[0087] SOCl2 (9.80 g, 82.4 mmol) was added to M-D3 (3.30 g, 10.1 mmol), and the mixture was refluxed at 60 °C for 3 hours. After the reaction was complete, excess SOCl2 was removed by vacuum distillation, and anhydrous methanol (51 g) degassed with nitrogen was added. CH3ONa (sodium methoxide) (1.09 g, 20.2 mmol) was slowly added under ice bath cooling, and the reaction was maintained at 0 °C for 2 hours, then heated to room temperature and continued for 3 hours. The reaction solution was quenched with saturated NH4Cl solution (50 g), and extracted with ethyl acetate. The organic layer was obtained by separation. The organic layer was washed, dried, filtered, and concentrated to obtain a brown solid. The solid was recrystallized from toluene to obtain a white solid M-D4 (2.81 g, 8.52 mmol, yield: 84.4%). The 1H NMR data of the product are shown below. Based on these results, the obtained solid was confirmed to be the target M-D4.

[0088] 1H-NMR (500MHz, [D6]-DMSO): δ (ppm) = 7.41 (d, 2H), 7.37 (d, 2H), 7.25 (t, 2H), 6.83 (d , 2H), 6.80(m, 2H), 6.15(d, 1H), 5.58(d, 1H), 3.82(m, 1H), 2.83(m, 2H), 1.93(s, 3H).

[0089] Anisole (38 g) degassed by nitrogen blowing was added to M-D4, followed by BPO (0.125 g, 0.516 mmol), and polymerization was initiated at 90 °C. After 12 hours of reaction, the reaction solution was slowly poured into methanol (200 g) to precipitate the product. The precipitate was filtered and recrystallized to obtain a white solid (1.98 g, yield: 79.2%). The target product was analyzed using a Fourier transform superconducting nuclear magnetic resonance (FT-NMR) device, "AVANCE III" (BRUKER), at 500 MHz, with deuterated N,N-dimethyl sulfoxide ([D6]-DMSO) as the solvent and tetramethylsilane (TMS) as the standard. The results are shown below. Based on these results, the obtained solid was confirmed as the target M1, and the NMR spectrum of copolymer M1 is shown below. Figure 3 As shown.

[0090] 1H-NMR (500MHz, [D6]-DMSO): δ (ppm) = 7.41 (d, 2H), 7.37 (d, 2H), 7.25 (t, 2H), 6.83 (d , 2H), 6.73(m, 2H), 3.82(m, 1H), 2.83(m, 2H), 1.64(m, 2H), 1.29(d, 3H), 0.96(s, 3H).

[0091] Copolymer M2 is:

[0092]

[0093] The synthesis process of copolymer M2 is as follows:

[0094]

[0095] Specifically, M-D2 (3.00 g, 9.90 mmol), H2O (60 g), and KMnO4 (3.12 g, 19.8 mmol) were added sequentially to a 500 mL four-necked flask, and the mixture was stirred at reflux for 1 hour. After the reaction was complete, the mixture was cooled to room temperature, and saturated Na2SO3 solution was added until the purple color disappeared. The pH was adjusted to 2-3 with 1N hydrochloric acid, and the precipitated solid was collected by filtration, washed, and dried to obtain M-E1 (2.81 g, 8.65 mmol, yield: 87.4%). The 1H NMR spectrum of the product is shown below. Based on this result, the obtained solid was confirmed to be the target M-E1.

[0096] 1H-NMR (500MHz, [D6]-DMSO): δ (ppm) = 11.0 (s, 1H), 8.19 (d, 2H), 7.69 (d, 2H), 7.37 (d , 2H), 6.83(d, 2H), 6.80(m, 2H), 6.15(d, 1H), 5.58(d, 1H), 1.93(s, 3H,), 0.23(s, 4H).

[0097] M-E1 (2.50 g, 7.68 mmol) was added to a 500 mL four-necked flask, followed by toluene (38 g) and BPO (0.126 g, 0.520 mmol). The mixture was heated to 85 °C and reacted for 10 hours. After the reaction was complete, the reaction solution was slowly poured into methanol (150 g) to precipitate the product. The precipitate was filtered to obtain a white solid. The solid was recrystallized to give the target product M2 (1.92 g, yield: 76.8%). Based on the following... 1 The H-NMR results confirmed that the polymer was the target product M2, and the NMR spectrum of copolymer M2 is as follows: Figure 4 As shown.

[0098] 1 H-NMR (500MHz, [D6]-DMSO): δ (ppm) = 11.00 (s, 1H), 8.19 (d, 2H), 8.19 (d, 2H), 7.69 (d , 2H), 7.37(d, 2H), 6.83(d, 2H), 6.73(m, 2H), 1.64(m, 2H), 1.29(d, 3H), 0.96(s, 3H).

[0099] Continuing on the above, this application provides a planar alignment composition for preparing a planar alignment layer in a display panel. The copolymer in the planar alignment composition contains a mesocrystalline structure, which enables the planar alignment layer to have an alignment function. Simultaneously, the copolymer also contains crosslinking groups, increasing the degree of crosslinking after film formation, improving the heat resistance and stability of the planar alignment layer, and facilitating the formation of a film layer with higher flatness. This allows the planar alignment layer to have a planarization function. Therefore, the planar alignment layer can simultaneously function as both a planarization layer and an alignment layer, simplifying the process and reducing costs.

[0100] Additionally, please refer to Figure 5 This application embodiment also provides a display panel, which includes a first substrate 11 and a planar alignment layer 31.

[0101] The planar alignment layer 31 is disposed on the first substrate 11, and the planar alignment layer 31 is made using the planar alignment composition as described in the above embodiments.

[0102] Specifically, the display panel further includes a color filter layer 20, which is disposed on the first substrate 11. The color filter layer 20 includes a plurality of color resist blocks 22 and a black matrix 21 located between adjacent color resist blocks 22. For example, the plurality of color resist blocks 22 may include red color resist blocks, green color resist blocks and blue color resist blocks.

[0103] Because the multiple color blocks 22 have different colors and materials, and there is a high degree of difference between them and the black matrix 21, the surface of the color filter layer 20 away from the first substrate 11 has a large step difference, which is not conducive to the subsequent process and the display of the display panel.

[0104] In this application, the planar alignment layer 31, prepared using the planar alignment composition, is disposed on the side of the color filter layer 20 away from the first substrate 11 and covers the color filter layer 20; it can be used to provide a planar film surface.

[0105] The planar alignment layer 31 has a first step on the side of its surface away from the first substrate 11, and the color filter layer 20 has a second step on the side of its surface away from the first substrate 11. The first step is smaller than the second step. Therefore, after the planar alignment layer 31 provided in this application is used to cover the color filter layer 20, the flatness can be effectively improved to provide a flat film surface.

[0106] It is understood that the first segment difference is the height difference between the highest and lowest points on the surface of the planar alignment layer 31 away from the first substrate 11; similarly, the second segment difference is the height difference between the highest and lowest points on the surface of the color filter layer 20 away from the first substrate 11.

[0107] In some embodiments, the display panel further includes a liquid crystal layer 40, and the liquid crystal layer 40 is disposed on the side of the planar alignment layer 31 away from the first substrate 11; wherein the planar alignment layer 31 is configured such that the liquid crystal molecules in the liquid crystal layer 40 have an initial alignment direction.

[0108] It should be noted that the copolymer in the planar alignment composition contains a mesocrystalline structure, which enables the planar alignment layer 31 to have an alignment function; at the same time, the copolymer also contains crosslinking groups, which increases the degree of crosslinking after film formation, improves the heat resistance and stability of the planar alignment layer 31, and is conducive to forming a film layer with higher flatness, thus enabling the planar alignment layer 31 to have a planarization function; therefore, the planar alignment layer 31 can simultaneously have the functions of a planarization layer and an alignment layer, which can simplify the process and reduce costs.

[0109] In some embodiments, the planar alignment layer contains a structure as shown in formula (2);

[0110]

[0111] R is obtained from B through a cross-linking reaction; that is, R can be generated by cross-linking reactions of epoxy groups, hydroxyl groups, carboxyl groups and glycidyl groups; * indicates a linking site.

[0112] n and A can be defined in the same way as in equation (1).

[0113] In some embodiments, the display panel further includes a second substrate 12 and an opposing alignment layer 32; wherein the second substrate 12 is disposed on the side of the liquid crystal layer 40 away from the planar alignment layer 31; the opposing alignment layer 32 is disposed between the second substrate 12 and the liquid crystal layer 40; wherein the material of the opposing alignment layer 32 includes polyimide.

[0114] It is understood that the opposing alignment layer 32 is configured such that the liquid crystal molecules in the liquid crystal layer 40 have an initial alignment orientation.

[0115] In some embodiments, the display panel provided in this application can be a horizontal field switching (HFS) type liquid crystal display panel; wherein, the display panel further includes a pixel electrode layer and a common electrode layer, and both the pixel electrode layer and the common electrode layer are disposed on the second substrate 12.

[0116] Furthermore, the pixel electrode layer is disposed between the second substrate 12 and the liquid crystal layer 40, and the pixel electrode layer is located on one side of the opposing alignment layer 32 along the thickness direction of the display panel; the common electrode layer is disposed between the second substrate 12 and the liquid crystal layer 40, and the common electrode layer is located on one side of the opposing alignment layer 32 along the thickness direction of the display panel; wherein, the pixel electrode layer and the common electrode layer are configured to jointly form a horizontal electric field; and the horizontal electric field is used to drive the liquid crystal molecules in the liquid crystal layer 40 to deflect, thereby controlling the polarization direction of the light passing through the liquid crystal layer 40.

[0117] It is understood that the display panel also includes a thin-film transistor layer disposed on the second substrate 12, and the pixel electrode layer can be connected to the thin-film transistors in the thin-film transistor layer to provide signals to the pixel electrodes in the pixel electrode layer, while the common electrode in the common electrode layer can provide signals using a common signal line.

[0118] In some embodiments, the pixel electrode layer and the common electrode layer are both disposed between the second substrate 12 and the opposing alignment layer 32; further, they can be disposed between the thin film transistor layer and the liquid crystal layer 40.

[0119] In some embodiments, the pixel electrode layer and the common electrode layer may be located in the same film layer, and the pixel electrodes in the pixel electrode layer and the common electrodes in the common electrode layer are spaced apart.

[0120] In some embodiments, the pixel electrode layer and the common electrode layer are two film layers spaced apart along the thickness direction of the display panel; wherein, the pixel electrode layer may be located between the common electrode and the second substrate 12, or the common electrode layer may be located between the pixel electrode layer and the second substrate 12.

[0121] Furthermore, this application provides Embodiment 1, Embodiment 2, and a comparative example to verify the performance of the planar alignment layer 31 and the display panel prepared by the planar alignment composition provided in this application.

[0122] It should be noted that, except for the material of the planar alignment layer, the structures of Examples 1, 2 and the comparative examples are the same.

[0123] In Example 1, the first planar alignment layer was prepared using copolymer M1 with a mass fraction of 83%, crosslinking agent with a mass fraction of 0.5%, and solvent with a mass fraction of 16.5%.

[0124] The crosslinking agent is:

[0125]

[0126] The solvent is propylene glycol monomethyl ether acetate.

[0127] In Example 2, the second planar alignment layer was prepared using copolymer M2 with a mass fraction of 83%, crosslinking agent with a mass fraction of 0.5%, and solvent with a mass fraction of 16.5%.

[0128] The crosslinking agent is:

[0129]

[0130] The solvent is propylene glycol monomethyl ether acetate.

[0131] In the comparative example, the third planar alignment layer was prepared using a comparative copolymer with a mass fraction of 83%, a crosslinking agent with a mass fraction of 0.5%, and a solvent with a mass fraction of 16.5%.

[0132] The comparative copolymer is:

[0133] Where n is defined in the same way as in equation (1).

[0134] The crosslinking agent is:

[0135]

[0136] The solvent is propylene glycol monomethyl ether acetate.

[0137] Furthermore, transparency, planarization, and long-term AC drive tests were performed on the first planar alignment layer, the second planar alignment layer, and the third planar alignment layer formed in Examples 1, 2, and the Comparative Example.

[0138] (I) Transparency Evaluation

[0139] Materials containing those from Examples 1, 2, and the comparative examples were coated onto a quartz substrate using nanoimprint lithography. The substrate was then baked on a hot plate at 110°C for 120 seconds, followed by baking in a hot air circulating oven at 230°C for 30 minutes to form a 2.5 μm cured film (such as a first planar alignment layer, a second planar alignment layer, and a third planar alignment layer). The transmittance of the cured film relative to a wavelength of 550 nm was measured using an MPCD-7000.

[0140] (II) Flatness Evaluation

[0141] Materials containing those from Examples 1, 2, and the comparative examples were coated onto a step-differential glass substrate with a height of 1.0 μm, a linewidth of 100 μm, and a spacing of 40 μm using nanoimprinting. The substrate was then baked on a hot plate at 120°C for 120 seconds, followed by baking in a hot air circulating oven at 230°C for 30 minutes to form a 2 μm cured film (such as a first planar alignment layer, a second planar alignment layer, and a third planar alignment layer). The film thickness was measured using a Quanta 200 SEM, and the planarization rate was calculated using the formula: DOP = 100 * {1 - [coating thickness difference (μm) / height of the step-differential substrate (1.0 μm)]}.

[0142] (III) Long-term communication-driven testing

[0143] Fabrication of liquid crystal cells:

[0144] CF board: The materials of Examples 1, 2 and the comparative examples are used by nanoimprinting on a substrate containing glass / R / G / B;

[0145] TFT board: Prepare glass / ITO / PI substrate according to the LCD-TFT panel manufacturing process;

[0146] Curing: After the materials of Example 1, Example 2 and Comparative Example were coated on the CF substrate, they were placed on a hot plate at 120°C and baked for 120 seconds, and then placed in a hot air circulating oven at 230°C and baked for 30 minutes to form a 2μm cured film.

[0147] Orientation: The cured film undergoes nylon cloth friction orientation. The specific process involves using a friction machine with rollers covered with cotton cloth, performing seven friction treatments at a roller speed of 1000 rpm, a platform movement speed of 20 cm / s, and a bristle indentation length of 0.4 mm. The orientation of the PI film is the same as that of the OC layer described above.

[0148] Cell Assembly: Following the LCD-TFT process, the CF board and TFT board obtained in the above steps are used as a group. A sealant is printed on the substrate in a manner other than the liquid crystal injection port. The other substrate is then bonded together with the film surfaces facing each other and the friction directions being antiparallel. The sealant is then cured to create an empty cell with a cell gap of 3.5 μm. Negative liquid crystal MLC 2767 (manufactured by Merck) is injected into this empty cell using a depressurized injection method. The injection port is then sealed to obtain the liquid crystal cell.

[0149] Evaluation of image retention caused by long-term AC drive: Using the liquid crystal cell fabricated above, an AC voltage of ±6V at a frequency of 60Hz was applied for 120 hours in a constant temperature environment of 60°C. Then, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and the cell was left at room temperature for one day. After placement, the liquid crystal cell was placed between two polarizers arranged orthogonally to the polarization axes. With no voltage applied, the backlight was turned on, and the arrangement angle of the liquid crystal cell was adjusted to minimize the brightness of the transmitted light. Then, the rotation angle Δ was calculated as the angle by which the liquid crystal cell rotated from the darkest angle of the second region of the first pixel to the darkest angle of the first region of the first pixel. Similarly, in the second pixel, the second region and the first region were compared, and the same angle Δ was calculated.

[0150] Based on the above, we obtained the results shown in Table 1 below.

[0151] Table 1

[0152]

[0153] As shown in Table 1, the first and second planar alignment layers prepared by the alignment layer compositions provided in this application can achieve a high level of performance, and the AC image retention structure is much smaller than that of the third planar alignment layer obtained in the comparative example. The larger the AC image retention, the larger the angle of liquid crystal rotation under the same conditions, and the worse the anchoring effect of the alignment layer on the liquid crystal. After AC driving, the alignment layer cannot restore the liquid crystal to its initial state, which leads to the appearance of image retention. Therefore, the planar alignment layer prepared by the planar alignment composition provided in this application has a more stable anchoring effect on the liquid crystal and a more stable alignment effect on the liquid crystal, which can effectively reduce the image retention phenomenon of the display panel and improve the display effect of the display panel.

[0154] In summary, the embodiments of this application provide a planar alignment composition for preparing a planar alignment layer in a display panel. The copolymer in the planar alignment composition contains a mesocrystalline structure, which enables the planar alignment layer to have an alignment function. Simultaneously, the copolymer also contains crosslinking groups, increasing the degree of crosslinking after film formation, improving the heat resistance and stability of the planar alignment layer, and facilitating the formation of a film layer with higher flatness. This allows the planar alignment layer to have a planarization function. Therefore, the planar alignment layer can simultaneously function as both a planarization layer and an alignment layer, simplifying the process and reducing costs.

[0155] In addition, this application embodiment also provides a display device, which may include the display panel described in the above embodiments.

[0156] It is understood that the display device includes the display panel described in the above embodiments. Therefore, the display device has the same beneficial effects as the display panel, which will not be described again here.

[0157] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0158] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0159] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0160] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A planar alignment composition, characterized in that, The planar alignment composition comprises a copolymer having a structural formula as shown in formula (1): Among them, A contains a mesocrystalline structure; B is selected from crosslinking groups; n is any integer between 30 and 500.

2. The planar alignment composition according to claim 1, characterized in that, A is selected from at least one of biphenyl and phenoxy groups.

3. The planar alignment composition according to claim 1, characterized in that, B is selected from at least one of epoxy, hydroxy, carboxyl, and glycidyl groups.

4. The planar alignment composition according to any one of claims 1 to 3, characterized in that, The copolymer is selected from at least one of the following compounds:

5. The planar alignment composition according to any one of claims 1 to 3, characterized in that, The planar alignment composition further includes a functional component comprising a crosslinking agent and a solvent, wherein the crosslinking agent contains at least one hydroxyl group.

6. The planar alignment composition according to claim 5, characterized in that, The copolymer accounts for 70% to 90% of the mass of the planar alignment composition; The crosslinking agent comprises, by mass, 0.1% to 10% of the planar alignment composition. The solvent accounts for 10% to 30% of the mass of the planar alignment composition.

7. A display panel, characterized in that, The display panel includes: First substrate; A planar alignment layer is disposed on the first substrate, wherein the planar alignment layer is prepared using the planar alignment composition according to any one of claims 1 to 6.

8. The display panel according to claim 7, characterized in that, The planar alignment layer contains a structure as shown in formula (2); R is obtained from B through a cross-linking reaction; * indicates a connection point.

9. The display panel according to claim 7, characterized in that, The display panel also includes: A color filter layer is disposed on the first substrate, and the planar alignment layer is disposed on the side of the color filter layer away from the first substrate and covers the color filter layer; A liquid crystal layer is disposed on the side of the planar alignment layer away from the first substrate; The planar alignment layer has a first step on the side of its surface away from the first substrate, and the color filter layer has a second step on the side of its surface away from the first substrate. The first step is smaller than the second step. The planar alignment layer is configured such that the liquid crystal molecules in the liquid crystal layer have an initial alignment direction.

10. The display panel according to claim 9, characterized in that, The display panel also includes: The second substrate is disposed on the side of the liquid crystal layer away from the planar alignment layer; An alignment layer is disposed between the second substrate and the liquid crystal layer; The material of the opposing alignment layer includes polyimide.

11. The display panel according to claim 10, characterized in that, The display panel also includes: A pixel electrode layer is disposed between the second substrate and the liquid crystal layer, and the pixel electrode layer is located on one side of the opposing alignment layer along the thickness direction of the display panel; A common electrode layer is disposed between the second substrate and the liquid crystal layer, and the common electrode layer is located on one side of the opposing alignment layer along the thickness direction of the display panel; The pixel electrode layer and the common electrode layer are configured to jointly form a horizontal electric field.

12. The display panel according to claim 9, characterized in that, The planar alignment layer is in contact with the color filter layer.

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