Method for producing liquid crystal alignment film, method for repairing defects of liquid crystal alignment film, method for producing liquid crystal device, and photo-alignment agent for repairing

Abstract

The invention provides a method for manufacturing a liquid crystal alignment film, a method for repairing defects of the liquid crystal alignment film, a method for manufacturing a liquid crystal device, and a photo-alignment agent for repairing, which can simply and accurately repair defects in the liquid crystal alignment film and can obtain a liquid crystal device with fully suppressed display defects. A liquid crystal alignment film is manufactured by a method including: a film forming step of forming a liquid crystal alignment film by applying a liquid crystal alignment agent on a substrate; a detection step for detecting defects existing in the liquid crystal alignment film; a coating step in which, when the defect is detected in the detection step, a region including the defect in the liquid crystal alignment film is partially coated with a light alignment agent for repair; and an irradiation step for irradiating a region including the application site of the repair photo-alignment agent with radiation.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a liquid crystal alignment film, a method for repairing defects in a liquid crystal alignment film, a method for manufacturing a liquid crystal device, and a photoalignment agent for repair. Background Technology

[0002] In liquid crystal displays (LCDs), especially those for large-screen televisions, viewing angle, transmittance, and response time are crucial performance indicators. To optimize these performance parameters, various operating modes have been developed for LCDs, including Twisted Nematic (TN) and Super Twisted Nematic (STN) types, Vertical Alignment (VA) types, Polymer Sustained Alignment (PSA) types, In-Plane Switching (IPS) types, and Fringe Field Switching (FFS) types. Furthermore, large-screen televisions utilizing these LCD technologies are currently in mass production.

[0003] Liquid crystal devices include a liquid crystal alignment film for controlling the orientation of liquid crystal molecules in liquid crystal cells. When defects exist in the liquid crystal alignment film, it may be impossible to control the orientation of liquid crystal molecules in the desired direction at the defective portion. When the orientation of liquid crystal molecules cannot be controlled in the desired direction, the orientation of the liquid crystal molecules becomes disordered, which may be perceived as a display defect (bright spot) by the observer of the liquid crystal device.

[0004] Therefore, various methods for repairing bright spot defects in liquid crystal display devices originating from defects in the liquid crystal alignment film have been proposed in the past (for example, see Patent Document 1 or Patent Document 2). Patent Document 1 discloses a method that corrects bright spot defects in a liquid crystal display device by irradiating the alignment film of an active matrix type liquid crystal display device with laser light and partially removing the alignment film. Patent Document 2 discloses a method that, when a defect exists in the liquid crystal alignment film formed on a substrate, repair ink is applied to the defective area of ​​the liquid crystal alignment film using a repair mold containing repair ink to repair the defect. Furthermore, in the past, during the manufacturing process of liquid crystal display devices, when defects are detected in the liquid crystal alignment film formed on the substrate, a reprocessing step is performed to peel off the liquid crystal alignment film from the substrate and re-form the liquid crystal alignment film.

[0005] [Existing Technical Documents]

[0006] [Patent Literature]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 8-15660

[0008] [Patent Document 2] International Publication No. 2010 / 140443 Summary of the Invention

[0009] [The problem the invention aims to solve]

[0010] However, as described in Patent Document 1, in the method of partially removing the liquid crystal alignment film by irradiating the liquid crystal alignment film inside the panel with laser light from the outside of the device after the liquid crystal display panel is constructed, there is a concern that the laser light may not be able to accurately irradiate the defective parts of the liquid crystal alignment film, or that the alignment disorder of liquid crystal molecules may occur in the parts irradiated with laser light, thereby failing to fully eliminate the bright spot defects.

[0011] Furthermore, regarding the regeneration of liquid crystal alignment films based on reprocessing, there are concerns that reprocessing may cause greater damage to the substrate, or that manufacturing costs may increase due to the need to re-form the liquid crystal alignment film after reprocessing. Moreover, when using repair inks, there are concerns that the alignment direction of liquid crystal molecules cannot be properly controlled in the repaired areas, thus failing to adequately eliminate bright spot defects.

[0012] The present invention was made in view of the above circumstances, and one of its objectives is to provide a method for manufacturing a liquid crystal alignment film that can easily and accurately repair defects present in the liquid crystal alignment film, thereby obtaining a liquid crystal device in which display defects are sufficiently suppressed.

[0013] [Technical means to solve the problem]

[0014] According to the present invention, a method for manufacturing a liquid crystal alignment film, a method for repairing defects in a liquid crystal alignment film, a method for manufacturing a liquid crystal device, and a photoalignment agent for repair are provided.

[0015] [1] A method for manufacturing a liquid crystal alignment film includes: a film forming step, wherein a liquid crystal alignment agent is coated on a substrate to form a liquid crystal alignment film; an inspection step, wherein defects present in the liquid crystal alignment film are inspected; a coating step, wherein, if the defect is detected by the inspection step, a repair photoalignment agent is partially coated on the area of ​​the liquid crystal alignment film containing the defect; and an irradiation step, wherein the area containing the repair photoalignment agent is irradiated with radiation.

[0016] [2] According to the manufacturing method of the liquid crystal alignment film described in [1], the photoaligning agent for repair contains a compound having photoaligning sites and a solvent.

[0017] [3] The method for manufacturing a liquid crystal alignment film according to [2] further includes a heat-applying step, wherein the heat-applying step applies heat to the photoaligning agent for repairing the area containing the defect that has been coated by the coating step.

[0018] [4] The method for manufacturing a liquid crystal alignment film according to any one of [1] to [3] further includes a removal step, wherein, if the defect is detected by the detection step, the removal step partially removes the region of the liquid crystal alignment film containing the defect before applying the repair photoalignment agent by the coating step.

[0019] [5] A method for repairing defects in a liquid crystal alignment film includes: a preparation step for preparing a substrate on which a liquid crystal alignment film is formed; an inspection step for inspecting defects present in the liquid crystal alignment film; a coating step for partially coating a repair photoalignment agent on the area of ​​the liquid crystal alignment film containing the defect when the defect is detected by the inspection step; and an irradiation step for irradiating the area containing the repair photoalignment agent with radiation.

[0020] [6] A method for manufacturing a liquid crystal device, comprising a liquid crystal alignment film manufactured by any one of [1] to [4] or a liquid crystal alignment film repaired by [5].

[0021] [7] A photoalignment agent for repair, used to partially form a repair film in a region of a liquid crystal alignment film formed on a substrate, the photoalignment agent containing a compound having photoalignment sites and a solvent.

[0022] [The effects of the invention]

[0023] This invention provides a simple and precise way to repair defects in liquid crystal alignment films, resulting in liquid crystal devices with fully suppressed display defects (bright spots). Attached Figure Description

[0024] Figure 1 This is a cross-sectional schematic diagram showing the general structure of a liquid crystal device.

[0025] Figure 2 This is a planar schematic diagram of the first substrate.

[0026] Figure 3 This is a cross-sectional schematic diagram showing the general structure of a liquid crystal device.

[0027] Figure 4 This is a flowchart illustrating the manufacturing method of a liquid crystal device.

[0028] Figure 5This is a flowchart illustrating the membrane repair process implemented through the membrane repair procedure.

[0029] Figure 6 (a) ~ Figure 6 (d) is a schematic diagram representing a series of treatments for membrane repair.

[0030] Figure 7 This is a flowchart illustrating another embodiment of the membrane repair process.

[0031] Explanation of icon numbers

[0032] 10: LCD device / display device

[0033] 11: First substrate

[0034] 12: Second substrate

[0035] 13: Liquid Crystal Layer

[0036] 14: Transparent substrate

[0037] 15: Pixel Electrode

[0038] 16: Thin Film Transistor (TFT)

[0039] 17: Scan signal line

[0040] 18: Data signal line

[0041] 19: Opposite Electrodes

[0042] 21: First orientation film

[0043] 22: Second orientation film

[0044] 23: First polarizing plate

[0045] 24: Second polarizing plate

[0046] 25: Common electrode

[0047] 26: Insulation layer

[0048] 30: Defects

[0049] 31: Defect Area

[0050] 32: Coating area

[0051] 33: Repair membrane

[0052] 41: Light source

[0053] 42: Imprint

[0054] S11, S12, S13, S21, S22, S23, S24, S25: Process Detailed Implementation

[0055] Hereinafter, embodiments will be described with reference to the accompanying drawings. Furthermore, in the following embodiments, parts that are identical or equivalent are labeled with the same symbols in the drawings, and descriptions of the parts with the same symbols are provided.

[0056] The following is a reference, firstly Figure 1 and Figure 2 The liquid crystal device obtained by the manufacturing method of this embodiment will be described. Figure 1 This is a cross-sectional schematic diagram showing the general structure of a liquid crystal device. Figure 2 This is a planar schematic diagram of the first substrate.

[0057] <Liquid crystal device>

[0058] The liquid crystal device 10 is a thin-film transistor (TFT) type liquid crystal display device, in which multiple pixels are arranged in a matrix in the display area. For example... Figure 1 As shown, the liquid crystal device 10 includes: a pair of substrates, including a first substrate 11 and a second substrate 12; and a liquid crystal layer 13 disposed between the first substrate 11 and the second substrate 12.

[0059] The first substrate 11 is a TFT substrate in which various wirings, such as pixel electrodes 15, TFTs 16 (which serve as switching elements), scan signal lines 17, and data signal lines 18, are disposed on a transparent substrate 14 comprising glass or resin. The pixel electrodes 15 comprise a transparent conductive material such as tin oxide (SnO2) or indium tin oxide (ITO), and are formed, for example, in a generally rectangular shape (see reference). Figure 2 For example, Figure 2 As shown, the pixel electrode 15 is a long, narrow rectangle in the direction in which the data signal line 18 extends.

[0060] The second substrate 12 is a counter substrate on which a counter electrode 19 containing a transparent conductor is disposed on a TFT 16 comprising glass or resin. The counter electrode 19 contains a transparent conductor such as ITO and is a common electrode shared by all pixel electrodes 15. The second substrate 12 is a color filter (CF) substrate comprising a black matrix and a color filter. The color filter has color layers of three colors, such as red (R), green (G), and blue (B). Alternatively, instead of using a structure in which a color filter is disposed on a counter substrate, a color filter on array (COA) disposed on a pixel substrate may be used.

[0061] exist Figure 1In the liquid crystal device 10 shown, a pair of electrodes is formed by a pixel electrode 15 disposed on a first substrate 11 and an opposing electrode 19 disposed on a second substrate 12. The structure of the liquid crystal device 10 is not limited to... Figure 1 The structure shown. For example, as Figure 3 As shown, the first substrate 11 may have a pair of electrodes, while the second substrate 12 may not have electrodes. In this case, the first substrate 11 may also have a common electrode 25, an insulating layer 26, and a pixel electrode 15 sequentially stacked on the surface of the transparent substrate 14, with the pixel electrode 15 and the common electrode 25 forming a pair of electrodes. For example, the common electrode 25 may be a surface electrode, and the pixel electrode 15 may be a comb-shaped electrode.

[0062] At least one of the first substrate 11 and the second substrate 12 has a liquid crystal alignment film formed thereon, which aligns liquid crystal molecules near the substrate surface in a predetermined direction relative to the substrate surface (i.e., the electrode arrangement surface). Figure 1 In the example shown, the liquid crystal device 10 has a first alignment film 21 formed on the electrode arrangement surface of the first substrate 11 and a second alignment film 22 formed on the electrode arrangement surface of the second substrate 12 as liquid crystal alignment films. These liquid crystal alignment films can be horizontally aligned, in which liquid crystal molecules are oriented approximately horizontally when no voltage is applied, or vertically aligned, in which liquid crystal molecules are oriented approximately vertically when no voltage is applied.

[0063] When the liquid crystal device 10 includes a horizontally aligned liquid crystal alignment film, the driving method of the liquid crystal device 10 may be, for example, a twisted nematic (TN) type, a super twisted nematic (STN) type, an in-plane switching (IPS) type, or a fringe field switching (FFS) type. Conversely, when the liquid crystal device 10 includes a vertically aligned liquid crystal alignment film, the driving method of the liquid crystal device 10 may be, for example, a VA type (including VA-MVA type, VA-PVA type, etc.) or a polymer-stable alignment (PSA) type. Alternatively, one of the first alignment film 21 and the second alignment film 22 may be a strongly anchored liquid crystal alignment film, and the other may be a weakly anchored liquid crystal alignment film.

[0064] The first alignment film 21 and the second alignment film 22 can be either rubbing alignment films or photoalignment films. A rubbing alignment film is formed by rubbing an organic film formed on a substrate using a liquid crystal alignment agent. A photoalignment film is formed by irradiating a photosensitive organic film formed on a substrate using a liquid crystal alignment agent with radiation, thereby performing an anisotropic process (photoalignment treatment). Furthermore, the liquid crystal device 10 can also align and segment each pixel disposed in the liquid crystal device 10, resulting in two or more regions within each pixel having different alignment directions.

[0065] As a liquid crystal alignment agent, a polymer composition containing a polymer and a solvent is preferably used. Examples of polymer backbones include: polyamic acid, polyimide, polyorganosiloxane, polyamic acid ester, polyamide, polyenamine, addition polymers, etc. Examples of addition polymers include: (meth)acrylic acid polymers, styrene polymers, maleimide polymers, styrene-maleimide polymers, (meth)acrylic acid-styrene-maleimide polymers, (meth)acrylic acid-styrene polymers, (meth)acrylic acid-maleimide polymers, etc. Furthermore, "(meth)acrylic acid" is a term that includes both "acrylic acid" and "methacrylic acid".

[0066] When a photoalignment film is formed on a substrate surface, a polymer having photoalignment sites is typically formulated as at least a part of the polymer component in the liquid crystal alignment agent. There are no particular limitations on the polymer having photoalignment sites, and known components used as polymer components of the photoalignment film can be used. Specific examples of photoalignment sites include: groups containing cinnamic acid structures, groups containing azobenzene, groups containing coumarin, groups containing chalcone, and structures containing cyclobutane, etc.

[0067] The liquid crystal alignment agent used to form the first alignment film 21 and the second alignment film 22 may contain only one polymer as a polymer component, or it may contain two or more polymers as polymer components. The liquid crystal alignment agent is typically a liquid composition formed by dissolving or dispersing the polymer components in one or more solvents. In addition to the polymer components, the liquid crystal alignment agent may also contain one or more additives such as crosslinking agents, adhesion promoters, ultraviolet absorbers, and photosensitizers as solid components.

[0068] The first substrate 11 and the second substrate 12 are arranged with the alignment film forming surfaces of the first substrate 11 and the second substrate 12 facing each other, and are separated by spacers (e.g., columnar spacers or beaded spacers) with a predetermined gap (cell gap). The first substrate 11 and the second substrate 12, which are arranged facing each other, are bonded together in the peripheral portion of each substrate by a sealing member.

[0069] A liquid crystal composition is filled into the space surrounded by the first substrate 11, the second substrate 12, and the sealing member. Thus, in the liquid crystal device 10, a liquid crystal layer 13 is formed between the first substrate 11 and the second substrate 12. The liquid crystal layer 13 may contain liquid crystals with negative dielectric anisotropy or liquid crystals with positive dielectric anisotropy. When the liquid crystal device 10 operates in horizontal mode, liquid crystals with positive dielectric anisotropy are generally used as the liquid crystal molecules in the liquid crystal layer 13. When the liquid crystal device 10 operates in vertical mode, liquid crystals with negative dielectric anisotropy are generally used as the liquid crystal molecules in the liquid crystal layer 13. Examples of liquid crystals include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred.

[0070] As liquid crystals, known liquid crystal materials can be used appropriately. Liquid crystal refractive index anisotropy. With the anisotropy of the refractive index of liquid crystals ( The delay represented by the product of the product of the thickness (d) of the liquid crystal layer 13 and the product of ... The method in which the liquid crystal layer 13 becomes the desired value should be appropriately set. For example, the thickness of the liquid crystal layer 13 is... .

[0071] A pair of polarizing plates are typically disposed on the outer sides of the first substrate 11 and the second substrate 12. The pair of polarizing plates includes a first polarizing plate 23 disposed on the outer surface of the first substrate 11 and a second polarizing plate 24 disposed on the outer surface of the second substrate 12. A terminal region (not shown) is provided at the outer edge of the first substrate 11, and the liquid crystal device 10 is driven by connecting integrated circuits (ICs) for driving liquid crystals to the terminal region. In this embodiment, the case of a TFT-type liquid crystal display device is described, but other driving methods (e.g., passive matrix method, plasma address method, etc.) are also possible.

[0072] <Method for Manufacturing a Liquid Crystal Device>

[0073] Next, a method for manufacturing a liquid crystal device 10 including a liquid crystal alignment film will be described. The liquid crystal device 10 can be manufactured by a method including the following film formation process and cell construction process. The substrate used in the film formation process varies depending on the desired operating mode of the liquid crystal device 10.

[0074] Film formation process: The process of coating a liquid crystal alignment agent onto a substrate to form a liquid crystal alignment film.

[0075] Cell construction process: The process of preparing a pair of substrates on which a liquid crystal alignment film is formed, and placing a liquid crystal layer between the pair of substrates arranged in opposite directions to construct a liquid crystal cell.

[0076] (Membrane formation process)

[0077] In the film formation process, firstly, on the substrate (on Figure 1 The liquid crystal alignment agent is coated onto the surfaces of the first substrate 11 and the second substrate 12. Preferably, the coating surface is heated to form a coating film on the substrate. In the manufacture of TN, STN, or VA type liquid crystal devices, two substrates, each with a patterned transparent conductive film, are used. Conversely, in the manufacture of IPS or FFS type liquid crystal devices, a substrate with a pair of electrodes and an opposing substrate without electrodes are used. The coating of the liquid crystal alignment agent onto the substrate surface is preferably performed using offset printing, flexographic printing, spin coating, roller coating, or inkjet printing.

[0078] After the liquid crystal alignment agent is coated onto the substrate, preheating (pre-baking) is preferably performed to prevent sagging or other defects. The pre-baking temperature is, for example, 30°C to 200°C, and the pre-baking time is, for example, 0.25 minutes to 10 minutes. Afterward, a calcination (post-baking) process is performed to remove solvents and other contaminants from the coated liquid crystal alignment agent. The calcination temperature (post-baking temperature) is, for example, 80°C to 250°C, and the post-baking time is, for example, 5 minutes to 200 minutes. The thickness of the film thus formed is preferably... .

[0079] In manufacturing TN, STN, IPS, or FFS type liquid crystal devices, a process (alignment treatment) is performed to impart liquid crystal alignment capability to the coating film formed on the substrate. This imparts the alignment capability of the liquid crystal molecules to the coating film, creating a liquid crystal alignment film. Preferably, the alignment treatment involves rubbing the surface of the coating film formed on the substrate with cotton or similar material, or photoalignment treatment that imparts liquid crystal alignment capability by irradiating the coating film with light. In manufacturing vertically aligned (VA) type liquid crystal devices, the formed coating film can be used directly as a liquid crystal alignment film. Alternatively, an alignment treatment can be performed on the coating film to further improve the liquid crystal alignment capability or to perform alignment separation. The liquid crystal alignment film preferred for vertically aligned liquid crystal devices is also preferred for PSA type liquid crystal devices.

[0080] In photo-alignment processing, light irradiation can be performed by methods such as: irradiating a coating after a post-baking process; irradiating a coating after a pre-baking process and before a post-baking process; or irradiating a coating during heating in at least one of the pre-baking or post-baking processes. As the radiation irradiating the coating, ultraviolet light and visible light with wavelengths from 150 nm to 800 nm can be used, for example. Ultraviolet light with wavelengths from 200 nm to 400 nm is preferred. When the radiation is polarized, it can be linearly polarized or partially polarized. When the radiation used is linearly polarized or partially polarized, irradiation can be performed from a direction perpendicular to the substrate surface, from an inclined direction, or a combination thereof. For unpolarized radiation, the irradiation direction is set to an inclined direction.

[0081] Examples of light sources used include: low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The preferred radiation dose to the substrate surface is... More preferably After light irradiation to impart orientation capability, the substrate surface may be cleaned using, for example, water, organic solvents (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0082] (Unit construction process)

[0083] In the cell fabrication process, a substrate with a liquid crystal alignment film formed in the manner described above is prepared, and a liquid crystal layer is disposed adjacent to the liquid crystal alignment film between a pair of substrates to manufacture a liquid crystal cell. In manufacturing liquid crystal devices, substrates with liquid crystal alignment films formed on each of a pair of substrates are typically used. Two methods can be used to manufacture a liquid crystal cell, for example. The first method involves first arranging two substrates facing each other with their liquid crystal alignment films facing each other through a gap (cell gap), bonding the peripheries of the two substrates together using a sealant, injecting liquid crystal into the cell gap surrounded by the substrate surfaces and the sealant, and sealing the injection hole. The second method is called One Drop Fill (ODF) method. In the second method, a sealant, for example, that is UV-curable is applied to a predetermined position on one of the two substrates with the liquid crystal alignment film formed, liquid crystal is then dropped onto the liquid crystal alignment film surface, the other substrate is bonded with its liquid crystal alignment films facing each other, and then the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby manufacturing a liquid crystal cell. As a sealing material, epoxy resin containing a hardener and alumina balls as spacers can be used, for example.

[0084] In the manufacture of a PSA-type liquid crystal device, the following process is performed: a liquid crystal cell is constructed by disposing of liquid crystal and a photopolymerizable compound together between two substrates; after the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of a pair of substrates in the liquid crystal cell.

[0085] For each operating mode of the liquid crystal cell, a polarizing plate is then attached to the outer surface of the liquid crystal cell as needed. Examples of polarizing plates include: a polarizing plate made by using a cellulose acetate protective film to hold a polarizing film called an "H film" that causes polyvinyl alcohol to absorb iodine while being oriented and extended, or a polarizing plate that includes the H film itself.

[0086] Liquid crystal devices manufactured in this way can be effectively used for a wide variety of applications. Specifically, they can be used in various display devices such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants (PDAs), digital cameras, mobile phones, smartphones, various monitors, LCD TVs, and information displays, as well as in dimming films, retardation films, etc.

[0087] Here, during the manufacturing process of the liquid crystal device 10, defects sometimes occur in the liquid crystal alignment film. Examples of defects in the liquid crystal alignment film include: foreign matter adhesion to the liquid crystal alignment film, uneven film thickness (abnormal film thickness), cleaning marks, scratches, etc. Examples of foreign matter include cutting debris from the liquid crystal alignment film during rubbing treatment, residue from the rubbing cloth, and environmental foreign matter (dust or grime, etc.). Furthermore, examples of abnormal film thickness in the liquid crystal alignment film include: pinholes, localized thinning or thickening caused by poor application of the liquid crystal alignment agent, and film peeling during rubbing treatment. Such defects in the liquid crystal alignment film can cause abnormal alignment of the liquid crystal molecules displayed by the liquid crystal alignment film, sometimes preventing the liquid crystal molecules from being aligned in the prescribed direction in the defective portion of the film. In such cases, the display in the defective portion of the film is inconsistent with the display in the normally aligned portion of the liquid crystal molecules, and is sometimes perceived by the observer as a display defect (bright spot). Especially in large LCD devices, the incidence of display defects caused by defects in the liquid crystal alignment film is high, which has a significant impact on the display quality of the LCD device.

[0088] Therefore, in this embodiment, during the manufacturing process of the liquid crystal device 10, after the film formation process and before the cell assembly process, a process is performed to detect defects in the liquid crystal alignment film obtained by the film formation process and to locally repair the alignment direction of the liquid crystal alignment film containing the defective regions (film repair process).

[0089] Figure 4 This is a flowchart illustrating the manufacturing process of the liquid crystal device 10 according to this embodiment. Figure 4 In the manufacturing process of the liquid crystal device 10 shown, firstly, a liquid crystal alignment film is formed on the substrate by coating a liquid crystal alignment agent on the substrate through a film forming process (S11). Next, a film repair process is performed to detect defects present in the liquid crystal alignment film, and if defects are detected, the liquid crystal alignment film containing the defective region is locally repaired (S12). Afterwards, a cell construction process is performed to construct a liquid crystal cell by placing a liquid crystal layer between two opposing substrates (S13). Furthermore, the method including the film forming process and the film repair process corresponds to the "method for manufacturing a liquid crystal alignment film" and the "method for repairing defects in a liquid crystal alignment film" of the present invention. The film forming process corresponds to the "preparation process for preparing a substrate on which a liquid crystal alignment film is formed" of the present invention.

[0090] When a liquid crystal cell is constructed with defects in the liquid crystal alignment film, in the liquid crystal device 10, the alignment state of the liquid crystal molecules cannot be properly controlled by the liquid crystal alignment film in the area corresponding to the defective portion of the liquid crystal alignment film, sometimes resulting in bright spots due to light leakage. In contrast, in the manufacturing method of this embodiment, if defects are detected in the liquid crystal alignment film before cell construction, the defective portion of the liquid crystal alignment film is locally repaired before cell construction, thereby suppressing the generation of bright spots caused by poor alignment. Furthermore, by locally repairing the defective area in the liquid crystal alignment film formed on the substrate, compared to peeling off the defective liquid crystal alignment film from the substrate and re-forming the film (reprocessing), cost reduction or time reduction can be achieved.

[0091] Next, refer to Figure 5 and Figure 6 (a) ~ Figure 6 (d) provides a detailed description of the membrane repair treatment in this embodiment. Figure 5 It means through Figure 4 A flowchart of the film repair process performed in the film repair step of the manufacturing method of the liquid crystal device 10 shown. Figure 6 (a) ~ Figure 6 (d) is a schematic diagram representing a series of processes for membrane remediation. For example... Figure 5 As shown, the membrane repair process of this embodiment includes a detection step, a removal step, a coating step, a heat application step, and an irradiation step. Furthermore, Figure 6 (a) ~ Figure 6 (d) shows the case where the first substrate 11 undergoes film repair treatment, but... Figure 4 In the film repair process, the second substrate 12 is also subjected to the same film repair treatment. Figure 6 (a) ~ Figure 6The arrow in (d) indicates the orientation direction of the liquid crystal in liquid crystal layer 13.

[0092] exist Figure 5 In the film repair process shown, firstly, defects 30 present in the liquid crystal alignment film (first alignment film 21) are detected through an inspection step (S21). The detection of defects 30 can be performed using known detection methods. As an example of a specific method, a mother substrate on which the liquid crystal alignment film is formed is positioned at a predetermined location in an Automatic Optical Inspection (AOI) apparatus, and image data of the substrate surface is acquired using a CCD camera or the like introduced into the AOI apparatus. Then, through image processing based on the acquired image data, the presence, location, or size of defects 30 in the liquid crystal alignment film on the mother substrate is detected (see reference). Figure 6 (a)). For the detected defect 30, for example, the type of defect 30 can be determined by comparing it with pre-stored known defect information through a defect detection system that uses deep learning.

[0093] In the S21 inspection process, if it is determined that there is no defect 30 in the liquid crystal alignment film on the substrate, the film repair process ends and proceeds to the next step. Figure 4 The cell construction process. Furthermore, when liquid crystal alignment films are formed on both the first substrate 11 and the second substrate 12, the film repair process ends when no defect 30 is found in the liquid crystal alignment films on either substrate. On the other hand, in the inspection process of S21, if it is determined that a defect 30 exists in the liquid crystal alignment film on the substrate, then in the removal process of S22, the area containing the defect 30 in the liquid crystal alignment film on the substrate is designated as a defect region 31, and the defect region 31 is partially removed.

[0094] There is no particular limitation on the method for partially removing the liquid crystal alignment film corresponding to the defect region 31. For example, such as Figure 6 As shown in (b), the following method is used: laser light is irradiated from light source 41 onto the defect region 31 of the liquid crystal alignment film on the substrate, thereby partially removing the liquid crystal alignment film of the defect region 31. The irradiation conditions of the laser light can be appropriately set, for example, with reference to the description in Japanese Patent Application Publication No. 8-15660. If the type of defect 30 is determined in the inspection process of S21, the liquid crystal alignment film corresponding to the defect region 31 can be removed in the removal process of S22 using a method corresponding to the determined type of defect 30.

[0095] The size of the defect area 31 is not particularly limited and can be appropriately set according to the size or shape of the defect 30. From the viewpoint of ensuring the quality of the display device 10, the defect area 31 is preferably minimized as much as possible. Specifically, it is preferably a portion of the defect 30, or the defect 30 and its surrounding area. For example, the defect area 31 is set to the same size as the defect 30, or a size that is slightly larger than the defect 30. The shape of the defect area 31 is also not particularly limited and can be a predetermined shape (e.g., circular, elliptical, rectangular), or an irregular shape based on the shape of the defect 30.

[0096] In step S21, defect 30 is detected. After removing the liquid crystal alignment film from defect region 31 in step S22, a repair photoalignment agent is partially coated onto defect region 31 after the liquid crystal alignment film has been partially removed in the coating step of step S23. The repair photoalignment agent is a photoalignment agent used to partially form a film in regions containing defects present in the liquid crystal alignment film formed on a substrate. It is a composition capable of forming an anisotropic film by photoalignment. In this invention, by coating the repair photoalignment agent onto defect region 31, a tiny film is formed in defect region 31. For the tiny film, anisotropy in the desired direction (i.e., the same direction as the alignment direction of the liquid crystal controlled by the first alignment film 21) is imparted by photoalignment in a subsequent step. In order to accurately impart anisotropy to the film and improve the alignment control of the liquid crystal in the defective region, the repair photoalignment agent preferably contains a compound with photoalignment sites and a solvent. Furthermore, the compound with photoalignment sites will also be referred to as "compound (A)" below.

[0097] The photo-orientation site of compound (A) is a site that can impart anisotropy to the film through photoreactions such as isomerization, dimerization, photo-Fries rearrangement, or decomposition induced by light irradiation. Specific examples of photo-orientation sites include: a group containing azobenzene or its derivatives as the basic framework; a group containing cinnamic acid or its derivatives (cinnamic acid structure) as the basic framework; a group containing chalcone or its derivatives as the basic framework; a group containing benzophenone or its derivatives as the basic framework; a group containing coumarin or its derivatives as the basic framework; a group containing cyclobutane or its derivatives as the basic framework; a group containing stilbene or its derivatives as the basic framework; and a group containing phenyl benzoate or its derivatives as the basic framework. Of these, the photo-orientation site of compound (A) is preferably selected from at least one group consisting of a group containing azobenzene, a group containing cinnamic acid, a group containing chalcone, a group containing stilbene, a structure containing cyclobutane, and a group containing phenyl benzoate. Furthermore, in terms of higher light sensitivity, the photo-orientation site of compound (A) is preferably a group containing cinnamic acid or a structure containing cyclobutane, and particularly preferably a cinnamic acid structure.

[0098] Compound (A) can be a polymer or a non-polymer. When compound (A) is a polymer, its main backbone is not particularly limited; examples include polyamic acid, polyimide, polyorganosiloxane, polyamic acid ester, polyamide, polyenamine, and addition polymers. Specific examples of addition polymers are the same as those exemplified as polymer components used as liquid crystal alignment agents in the formation of the first alignment film 21 and the second alignment film 22. When compound (A) is a polymer, it may have photo-alignment sites in the main chain or in the side chains. For ease of adjusting the film's orientation direction using photo-alignment methods and preferably for suppressing the generation of bright spots, compound (A) as a polymer preferably has photo-alignment sites in its side chains. When compound (A) is a polymer, its weight-average molecular weight is, for example, 1,000 to 500,000, preferably 5,000 to 100,000.

[0099] When compound (A) is a non-polymer, polymerizable compounds having photooriented sites can be listed as compound (A). In polymerizable compounds, functional groups capable of polymerization between the same or different types of functional groups by heat or light are preferably used as the polymerizable group; examples include (meth)acryloyl, vinyl, vinyloxy, vinylphenyl, maleimide, oxetyl, oxetylbutyl, etc. When compound (A) is a non-polymer, the molecular weight of compound (A) is, for example, 1,000 or less, preferably 800 or less.

[0100] From the viewpoint of accurately applying the photoaligning agent to specific areas, a solvent capable of dissolving or dispersing compound (A) is preferably used as the solvent component for the photoaligning agent used for restoration. Examples of such solvents include water, organic solvents, or mixtures of water and organic solvents. Specific examples of organic solvents include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons.

[0101] The photoaligning agent for repair may also contain components different from compound (A) and solvent. Examples of such components include: crosslinking agents, bonding aids, ultraviolet absorbers, and photosensitizers.

[0102] Regarding the method of applying a repair photoalignment agent to the defect area 31 on the substrate, there is no particular limitation as long as the repair photoalignment agent can be locally applied to the desired area on the substrate. Examples of methods for applying the repair photoalignment agent include: molding, inkjet printing, transfer printing, dispenser printing, spraying, and nanoimprinting. Among these, the molding method, for example as shown in International Publication No. 2010 / 140443, involves bringing a mold 42, which supplies liquid to its front end, into contact with the coating surface from above the substrate, and moving the mold 42 along the coating surface as needed, thereby applying liquid to the desired area. In this embodiment, by supplying the repair photoalignment agent from the front end of the mold 42 to the coating surface, the repair photoalignment agent is applied to the defect area 31 after the liquid crystal alignment film has been locally removed (see reference). Figure 6 (c)).

[0103] The size of the coating portion 32, which serves as the area for applying the photoalignment agent for repair, is not particularly limited and can be appropriately set according to the size or shape of the defect region 31, the type of defect, etc. From the viewpoint of minimizing the impact on the performance of the liquid crystal alignment film outside the defect region 31, the coating portion 32 is preferably set as the region corresponding to the defect region 31, or the defect region 31 and its surrounding area. For example, the coating portion 32 can be set to the same size as the defect region 31, or slightly larger than the defect region 31.

[0104] In step S23, a repair photoaligning agent is applied to the defect region 31. Then, in the subsequent heat-applying step, the repair photoaligning agent applied to the coating region 32 is heat-applied (S24). Through this heat-applying step, the solvent component is removed from the repair photoaligning agent on the substrate, and a tiny repair film 33 of the size corresponding to the defect region 31 is formed in the region containing the defect region 31 (i.e., the coating region 32). Furthermore, when the compound (A) is a non-polymer with polymerizable groups, the curing reaction of the compound (A) can be promoted by heat application based on the heat-applying step, thereby forming a repair film 33 with higher performance.

[0105] In one state of heat application in the heat application process, preheating (pre-baking) is first performed to remove the solvent from the photoalignant agent for repair coated on the coating area 32, followed by calcination (post-baking) to promote further reaction of compound (A) and improve the performance of the film. Regarding the heat application of the photoalignant agent for repair on the substrate, it can be performed locally on the coating area 32 or on the entire first substrate 11. When heat application is performed locally on the coating area 32, it can be performed, for example, by irradiating the area with infrared light for a short time (e.g., several seconds to several minutes).

[0106] Furthermore, when heat is applied to the entire substrate, the pre-baking temperature is preferably 30°C to 150°C, and the pre-baking time is preferably 0.05 minutes to 15 minutes, so as not to reduce the liquid crystal alignment capability applied to the portion of the liquid crystal alignment film other than the defect region 31. The post-baking temperature is preferably 80°C to 180°C, more preferably 80°C to 150°C. The post-baking time is preferably 1 minute to 100 minutes. From the viewpoint of minimizing the impact on the performance of the liquid crystal alignment film other than the defect region 31, it is preferable to locally heat the coating area 32 of the repair photoalignment agent during the heat application process.

[0107] In S24, after heat-applying the photoaligning agent for repair to the coated area 32, in the subsequent irradiation process, the coated area 32 of the photoaligning agent for repair is irradiated with radiation to perform photoalignment treatment (S25). Thus, the alignment direction of the liquid crystal controlled by the repair film 33 formed in the defect region 31 can be controlled to be the same as the alignment direction of the liquid crystal controlled by the first alignment film 21 (see reference). Figure 6 (d) Regarding the radiation irradiation of the coating portion 32, it can be performed locally on the area including the coating portion 32, or it can be performed on the entire surface of the first substrate 11. From the viewpoint of minimizing the impact on the performance of the liquid crystal alignment film other than the defect region 31, it is preferable to perform radiation irradiation on the coating portion 32 of the repair photoalignment agent, or the coating portion 32 and its surrounding area locally, during the irradiation process.

[0108] As the radiation used to irradiate the photoaligning agent for repair on the substrate, ultraviolet light and visible light containing wavelengths of 150 nm to 800 nm can be used, for example. The wavelength of the irradiation light can be appropriately set according to the type of photoaligning site of compound (A) to induce photoisomerization or photodimerization reactions in compound (A) contained in the photoaligning agent. For example, when the photoaligning site of compound (A) is a group containing a cinnamic acid structure, the wavelength of the irradiation light is preferably 313 nm; when the photoaligning site of compound (A) is a structure containing cyclobutane, the wavelength of the irradiation light is preferably 254 nm.

[0109] When the radiation is polarized, it can be linearly polarized or partially polarized. Furthermore, when linearly polarized or partially polarized radiation is used, the radiation irradiation only needs to be set to be consistent with the alignment direction of the liquid crystal controlled by the first alignment film 21. Specifically, the radiation irradiation of the repair film 33 can be performed from a direction perpendicular to the substrate surface, from an inclined direction, or a combination thereof. The light source used can be the same as that described when the first alignment film 21 and the second alignment film 22 are photoalignment films. The radiation irradiation amount is preferably... More preferably The thickness of the repair film 33 formed by the film repair treatment is preferably the same as that of the liquid crystal alignment films (first alignment film 21, second alignment film 22), for example, .

[0110] Through this series of processes, liquid crystal alignment films ( Figure 6 (a) ~ Figure 6 In (d), a repair film 33 is formed over the region including the defect 30 in the first alignment film 21), enabling control of the alignment of the liquid crystal in the liquid crystal layer 13 in a desired direction. Thus, for defective portions generated in the liquid crystal alignment film, the alignment direction of the liquid crystal can be controlled to align with the alignment direction controlled by the liquid crystal alignment film. Therefore, by this method, the region containing the defect 30 in the liquid crystal alignment film can be locally repaired before cell assembly, avoiding the generation of bright spots caused by poor alignment. Furthermore, since the region containing the defect 30 in the liquid crystal alignment film formed on the substrate is locally repaired, cost reduction can be achieved compared to conventional reprocessing.

[0111] The repair film 33 can be relatively easily and accurately given the ability to control the liquid crystal alignment in the same direction as the liquid crystal alignment direction controlled by the liquid crystal alignment films (first alignment film 21, second alignment film 22). In this respect, the film repair method of this embodiment can be particularly preferably applied to a horizontal mode liquid crystal device 10.

[0112] In the embodiments described above, for example, it can be implemented as follows.

[0113] The membrane repair process described in this embodiment is configured to include a detection step, a removal step, a coating step, a heat application step, and an irradiation step. However, it can also be configured to omit at least one of the removal step and the heat application step. For example, Figure 7 As shown, the membrane repair process can be configured to have an inspection step, a coating step, and an irradiation step, but without a removal step and a heat application step. Alternatively, the membrane repair process can be configured to have an inspection step, a removal step, a coating step, and an irradiation step, but without a heat application step, or it can be configured to have an inspection step, a coating step, a heat application step, and an irradiation step, but without a removal step.

Claims

1. A method for manufacturing a liquid crystal alignment film, comprising: In the film formation process, a liquid crystal alignment agent is coated on a substrate to form a liquid crystal alignment film; The inspection process involves detecting defects present in the liquid crystal alignment film; In the coating process, if the defect is detected by the inspection process, a repair photoalignment agent is partially coated on the area of ​​the liquid crystal alignment film containing the defect. as well as The irradiation process involves irradiating the area containing the photo-aligning agent for repair with radiation.

2. The method for manufacturing a liquid crystal alignment film according to claim 1, wherein the photoaligning agent for repair contains a compound having photoaligning sites and a solvent.

3. The method for manufacturing a liquid crystal alignment film according to claim 2 further includes a heat-applying step, wherein the heat-applying step applies heat to the photoaligning agent for repairing the defect that has been applied to the region containing the defect by the coating step.

4. The method for manufacturing a liquid crystal alignment film according to claim 1 further includes a removal step, wherein, if the defect is detected by the detection step, the removal step partially removes the region of the liquid crystal alignment film containing the defect before applying the repair photoalignment agent by the coating step.

5. A method for repairing defects in a liquid crystal alignment film, comprising: Preparation process: preparing a substrate on which a liquid crystal alignment film is formed; The inspection process involves detecting defects present in the liquid crystal alignment film; In the coating process, if the defect is detected by the inspection process, a repair photoalignment agent is partially coated on the area of ​​the liquid crystal alignment film containing the defect. as well as The irradiation process involves irradiating the area containing the photo-aligning agent for repair with radiation.

6. A method for manufacturing a liquid crystal device, comprising a liquid crystal alignment film manufactured by the method for manufacturing a liquid crystal alignment film according to any one of claims 1 to 4, or a liquid crystal alignment film repaired by the defect repair method for the liquid crystal alignment film according to claim 5.

7. A photoalignment agent for repair, used to partially form a repair film in regions of a liquid crystal alignment film formed on a substrate, including defects present in the liquid crystal alignment film. The repair photoalignment agent contains a compound with photoalignment sites and a solvent.

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