Liquid crystal alignment film structure of foldable electronic reader

Abstract

The invention discloses a liquid crystal alignment film structure of a foldable electronic reader, which relates to the technical field of liquid crystal alignment films and comprises a surface treatment layer, a protective layer, a photosensitive layer, an alignment layer, an adhesion layer and a substrate layer which are sequentially distributed from top to bottom, the substrate layer is prepared from a mixture of polyethylene glycol terephthalate and polyethylene naphthalate, the orientation layer is prepared from polyimide, and the adhesion layer, the photosensitive layer, the protection layer and the surface treatment layer are used as auxiliary materials to jointly form the liquid crystal orientation film structure, so that the preparation is simple and easy to operate; and the prepared liquid crystal alignment film has good thermal stability, tensile property and optical property, is higher in mechanical strength, can keep stable performance in a high-temperature environment, can provide a clearer display effect, is expanded in application range, and is convenient for wide popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal alignment films, and in particular to a liquid crystal alignment film structure of a foldable electronic reader. Background Art

[0002] A foldable e-reader is a new type of electronic reading device that uses foldable electronic ink screen technology, allowing the device to be easily folded up while maintaining a large-screen reading experience, making it easy to carry and store. The liquid crystal orientation film of a foldable e-reader is a special film that is used to guide liquid crystal molecules to arrange in a specific direction to achieve the functions of a liquid crystal display device. In order to adapt to the folding of the screen, the liquid crystal orientation film needs to have good flexibility and ductility, and be able to maintain its function after multiple foldings. Frequent folding may cause damage to the orientation film, so the liquid crystal orientation film of a foldable e-reader also needs to have good durability.

[0003] Most of the liquid crystal orientation films of existing foldable electronic readers have a single structure. Not only is the preparation process complicated, but the prepared liquid crystal orientation film products do not have good tensile strength, resulting in poor mechanical properties. They are prone to deformation or discoloration in high temperature environments and do not have good thermal stability. In addition, the light transmittance of the liquid crystal orientation films of existing foldable electronic readers needs to be improved, and they cannot provide a clearer display effect. The optical performance is not excellent enough, which limits the scope of application and is not convenient for widespread promotion and application. Therefore, the present invention proposes a liquid crystal orientation film structure of a foldable electronic reader to solve the problems existing in the prior art. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to propose a liquid crystal alignment film structure for a foldable electronic reader, which solves the problems that the liquid crystal alignment film structure of the existing foldable electronic reader does not have good tensile strength, is prone to deformation or discoloration in high temperature environment, and the light transmittance needs to be improved.

[0005] In order to achieve the purpose of the present invention, the present invention is implemented through the following technical scheme: a liquid crystal orientation film structure of a foldable electronic reader, comprising a base layer and an orientation layer, the base layer is located below the orientation layer, an adhesion layer is bonded between the upper surface of the base layer and the lower surface of the orientation layer, a photosensitive layer is coated on the side of the orientation layer away from the adhesion layer, a protective layer is coated on the side of the photosensitive layer away from the orientation layer, a surface treatment layer is coated on the side of the protective layer away from the photosensitive layer, and the surface treatment layer, protective layer, photosensitive layer, orientation layer, adhesion layer and base layer are arranged in sequence from top to bottom.

[0006] A further improvement is that the base layer is prepared by mixing polyethylene terephthalate and polyethylene naphthalate and adopting a calendering process, and the mixing mass ratio of polyethylene terephthalate and polyethylene naphthalate is 1:1-2.

[0007] A further improvement is that the adhesion layer is an adhesion promoter coated on the upper surface of the base layer, and the adhesion promoter is selected from one of a silane coupling agent or a titanate coupling agent.

[0008] A further improvement is that the alignment layer is made of polyimide, which is formed by the polycondensation reaction of dianhydride and diamine.

[0009] A further improvement is that the photosensitive layer is a photosensitive group, and the photosensitive group is selected from one of an azobenzene group and a styrene group.

[0010] A further improvement is that the protective layer is prepared by mixing polyurethane and acrylic resin, and the mixing mass ratio of the polyurethane and acrylic resin is 1:1-2.

[0011] A further improvement is that the surface treatment layer is prepared by mixing polyvinyl alcohol and polyacrylic acid, and the mixing mass ratio of polyvinyl alcohol to polyacrylic acid is 1:1-2.

[0012] A further improvement is that the method for preparing the liquid crystal alignment film comprises the following steps:

[0013] Step 1: Mix ethylene terephthalate and polyethylene naphthalate in a preset ratio and calender them into a film by a calendering method, cut them and then perform ultrasonic cleaning to obtain a plastic substrate as a base layer;

[0014] Step 2: coating an adhesion promoter on the upper surface of the substrate layer as an adhesion layer, and then coating polyimide on the upper surface of the adhesion layer, and forming an alignment layer after curing, and then forming an ordered alignment structure on the upper surface of the alignment layer by rubbing alignment or photo-alignment technology;

[0015] Step 3: Mixing the photosensitive group, alcohol solvent and deionized water in a mass ratio of 1:5:5 to prepare a photosensitive coating solution, coating the photosensitive coating solution on the upper surface of the alignment layer, and forming a photosensitive layer after curing, and using ultraviolet light to activate the photosensitive group;

[0016] Step 4: Mixing polyurethane, acrylic resin, ketone solvent and deionized water in a mass ratio of 1:1 to 2:5:5 to prepare a protective coating solution, and then coating the protective coating solution on the upper surface of the photosensitive layer, and forming a protective layer after curing;

[0017] Step 5: polyvinyl alcohol, polyacrylic acid and deionized water are mixed in a mass ratio of 1:1 to 2:10 to prepare a surface treatment coating solution, and then the surface treatment coating solution is coated on the upper surface of the protective layer to form a surface treatment layer after solidification, thereby obtaining a finished liquid crystal alignment film;

[0018] Step 6: Heat the finished liquid crystal alignment film to 200-250° C., keep the temperature for 30-40 minutes, then stop heating and cool naturally to complete the post-annealing treatment of the liquid crystal alignment film.

[0019] The beneficial effects of the present invention are as follows: the present invention uses a mixture of polyethylene terephthalate and polyethylene naphthalate to form a base layer, uses polyimide as a raw material to form an orientation layer, and is supplemented with an adhesion layer, a photosensitive layer, a protective layer and a surface treatment layer to form a liquid crystal orientation film structure. The preparation is not only simple and easy to operate, but also the prepared liquid crystal orientation film has good thermal stability, tensile strength and optical properties, higher mechanical strength, can maintain stable performance in a high temperature environment, and can provide a clearer display effect, so the scope of application is expanded, which is convenient for wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the layered structure of the liquid crystal alignment film of the foldable electronic reader of the present invention.

[0021] Among them: 1. Base layer; 2. Orientation layer; 3. Adhesion layer; 4. Photosensitive layer; 5. Protective layer; 6. Surface treatment layer. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] An electronic reader, also known as an electronic book reader or e-reader, is a portable electronic device designed specifically for reading digital texts and electronic books. This device usually provides a reading experience similar to that of paper books, and has functions such as storing a large number of books, adjusting font size, and backlight reading, making reading more convenient and comfortable. The emergence and development of electronic readers has greatly enriched people's reading methods, making it more convenient and environmentally friendly to obtain and read information;

[0024] A foldable e-reader is a new type of electronic reading device. It uses foldable electronic ink screen technology, which allows the device to be easily folded up while maintaining a large-screen reading experience, making it easy to carry and store. The design of this reader is inspired by traditional paper books. Users can open and close the e-reader like flipping through ordinary books. The biggest feature of a foldable e-reader is that its screen can be folded, thanks to the development of flexible electronic ink screen technology. This screen will not leave obvious creases after folding, ensuring the visual experience when reading. The liquid crystal orientation film of a foldable e-reader is a special film used to guide liquid crystal molecules to align in a specific direction to achieve the function of a liquid crystal display device;

[0025] Based on the findings in the prior art, the liquid crystal orientation films of current foldable electronic readers mostly have a single structure, and the prepared liquid crystal orientation film products do not have good tensile strength, resulting in poor mechanical properties, and are prone to deformation or discoloration in high temperature environments, and do not have good thermal stability. In addition, the light transmittance of the liquid crystal orientation films of existing foldable electronic readers needs to be improved, and a clearer display effect cannot be provided, and the optical performance is not excellent enough.

[0026] Embodiment 1

[0027] For the problems existing in the above-mentioned prior art, see Figure 1 , this embodiment provides a liquid crystal alignment film structure of a foldable electronic reader, comprising a surface treatment layer 6, a protective layer 5, a photosensitive layer 4, an alignment layer 2, an adhesive layer 3 and a base layer 1 which are sequentially arranged from top to bottom, wherein the base layer 1 and the alignment layer 2 are bonded by the adhesive layer 3, the photosensitive layer 4 is coated on the upper surface of the alignment layer 2, the protective layer 5 is coated on the upper surface of the photosensitive layer 4, the surface treatment layer 6 is coated on the upper surface of the protective layer 5, and the surface treatment layer 6, the protective layer 5, the photosensitive layer 4, the alignment layer 2, the adhesive layer 3 and the base layer 1 together constitute the liquid crystal alignment film of this embodiment;

[0028] The base layer 1 in this example is prepared by mixing polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) in a mass ratio of 1:1 to provide support for the liquid crystal alignment film. Compared with traditional materials, the base layer 1 is thinner and more flexible, and is suitable for portable and flexible display devices.

[0029] The adhesion layer 2 in this embodiment is an adhesion promoter coated on the upper surface of the base layer 1. The adhesion promoter is selected from a silane coupling agent or a titanate coupling agent. The adhesion promoter is coated on the upper surface of the base layer 1 to enhance the adhesion between the alignment layer 2 and the base layer 1, thereby improving the overall structural strength of the liquid crystal alignment film.

[0030] In this embodiment, the alignment layer 2 is made of polyimide (PI), which is formed by the polycondensation reaction of dianhydride with a benzophenone structure and diamine containing active hydrogen. The polyimide with photosensitivity is formed by the polycondensation reaction of dianhydride and diamine, which provides good photosensitivity for the liquid crystal alignment film and guides the alignment of liquid crystal molecules.

[0031] The photosensitive layer 4 of this embodiment is a photosensitive group, and the photosensitive group is selected from an azobenzene group. Under ultraviolet light, the azobenzene group can undergo cis-trans isomerization, thereby changing the geometric configuration of the molecule. This change can be used to control the orientation of liquid crystal molecules, or styrene groups. Styrene groups can undergo free radical polymerization under the action of light, resulting in changes in the physical properties of the material. This group is commonly used in the preparation of one of the photosensitive polymers, used for light-controlled orientation, so that the liquid crystal alignment film has good light response performance;

[0032] The protective layer 5 of this embodiment is prepared by mixing polyurethane (PU) and acrylic resin in a mass ratio of 1:1, and protects the alignment layer 2 to prevent the alignment layer 2 from being damaged;

[0033] The surface treatment layer 6 of this embodiment is prepared by mixing polyvinyl alcohol (PVA) and polyacrylic acid (PAA) in a mass ratio of 1:1, and is used to improve the surface properties of the liquid crystal alignment film, increase hydrophilicity, and enhance alignment ability.

[0034] This embodiment also provides a method for preparing a liquid crystal alignment film of a foldable electronic reader, comprising the following steps:

[0035] Step 1: Preparation of base layer

[0036] The ethylene terephthalate and polyethylene naphthalate prepared by mixing in a mass ratio of 1:1 are calendered into a film by a calendering method. The calendered film is cut and then cleaned by a good ultrasonic cleaning instrument to ensure that it is dust-free and dirt-free. After cleaning, it is dried to obtain a plastic substrate as the base layer 1;

[0037] Step 2: Preparation of orientation layer

[0038] An adhesion promoter is coated on the upper surface of the base layer 1 prepared in step 1 as an adhesion layer 3, and polyimide is then coated on the upper surface of the adhesion layer 3 and cured by heating to form an alignment layer 2, and then an orderly alignment structure is formed on the upper surface of the alignment layer 2 by a rubbing alignment technique;

[0039] Step 3: Preparation of photosensitive layer

[0040] The photosensitive group, alcohol solvent (methanol or ethanol) and deionized water are mixed uniformly in a mass ratio of 1:5:5 to prepare a uniform photosensitive coating solution, and then the photosensitive coating solution is coated on the upper surface of the alignment layer 2 prepared in step 2 by spraying, and cured by heating to form a photosensitive layer 4, and then the photosensitive layer 4 is irradiated with ultraviolet light to activate the photosensitive group;

[0041] Step 4: Preparation of protective layer

[0042] The polyurethane, acrylic resin, ketone solvent (acetone) and deionized water are mixed uniformly in a mass ratio of 1:1:5:5 to prepare a uniform protective coating solution, and then the protective coating solution is applied to the upper surface of the photosensitive layer 4 prepared in step 3 by spin coating, and is cured by drying to form a protective layer 5;

[0043] Step 5: Preparation of protective layer

[0044] Polyvinyl alcohol, polyacrylic acid and deionized water are mixed uniformly in a mass ratio of 1:1:10 to prepare a uniform surface treatment coating solution, and then the surface treatment coating solution is coated on the upper surface of the protective layer 5 prepared in step 4 by a slit coating method, and dried to form a surface treatment layer 6 after solidification, thereby obtaining a finished liquid crystal alignment film;

[0045] Step 6: Finished product annealing and post-processing

[0046] The finished liquid crystal alignment film obtained in step five is heated to 200°C at a heating rate of 10°C / min, and then kept warm for 30 minutes. Then the heating is stopped and naturally cooled to complete the annealing treatment, release the residual stress generated in the alignment film during the preparation process, improve the stability of the film, improve the crystallinity, thereby improving the mechanical strength and thermal stability of the alignment film, and comprehensively improve the microstructure and performance of the material.

[0047] Embodiment 2

[0048] For the problems existing in the above-mentioned prior art, see Figure 1 , this embodiment provides a liquid crystal alignment film structure of a foldable electronic reader, comprising a surface treatment layer 6, a protective layer 5, a photosensitive layer 4, an alignment layer 2, an adhesive layer 3 and a base layer 1 which are sequentially arranged from top to bottom, wherein the base layer 1 and the alignment layer 2 are bonded by the adhesive layer 3, the photosensitive layer 4 is coated on the upper surface of the alignment layer 2, the protective layer 5 is coated on the upper surface of the photosensitive layer 4, the surface treatment layer 6 is coated on the upper surface of the protective layer 5, and the surface treatment layer 6, the protective layer 5, the photosensitive layer 4, the alignment layer 2, the adhesive layer 3 and the base layer 1 together constitute the liquid crystal alignment film of this embodiment;

[0049] The base layer 1 in this example is prepared by mixing polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) in a mass ratio of 1:2 to provide support for the liquid crystal alignment film. Compared with traditional materials, the base layer 1 is thinner and more flexible, and is suitable for portable and flexible display devices.

[0050] The adhesion layer 2 in this embodiment is an adhesion promoter coated on the upper surface of the base layer 1. The adhesion promoter is selected from a silane coupling agent or a titanate coupling agent. The adhesion promoter is coated on the upper surface of the base layer 1 to enhance the adhesion between the alignment layer 2 and the base layer 1, thereby improving the overall structural strength of the liquid crystal alignment film.

[0051] In this embodiment, the alignment layer 2 is made of polyimide (PI), which is formed by the polycondensation reaction of dianhydride with a benzophenone structure and diamine containing active hydrogen. The polyimide with photosensitivity is formed by the polycondensation reaction of dianhydride and diamine, which provides good photosensitivity for the liquid crystal alignment film and guides the alignment of liquid crystal molecules.

[0052] The photosensitive layer 4 of this embodiment is a photosensitive group, and the photosensitive group is selected from an azobenzene group. Under ultraviolet light, the azobenzene group can undergo cis-trans isomerization, thereby changing the geometric configuration of the molecule. This change can be used to control the orientation of liquid crystal molecules, or styrene groups. Styrene groups can undergo free radical polymerization under the action of light, resulting in changes in the physical properties of the material. This group is commonly used in the preparation of one of the photosensitive polymers, used for light-controlled orientation, so that the liquid crystal alignment film has good light response performance;

[0053] The protective layer 5 of this embodiment is prepared by mixing polyurethane (PU) and acrylic resin in a mass ratio of 1:2, and protects the alignment layer 2 to prevent the alignment layer 2 from being damaged;

[0054] The surface treatment layer 6 of this embodiment is prepared by mixing polyvinyl alcohol (PVA) and polyacrylic acid (PAA) in a mass ratio of 1:2, and is used to improve the surface properties of the liquid crystal alignment film, increase hydrophilicity, and enhance alignment ability.

[0055] This embodiment also provides a method for preparing a liquid crystal alignment film of a foldable electronic reader, comprising the following steps:

[0056] Step 1: Preparation of base layer

[0057] The ethylene terephthalate and polyethylene naphthalate prepared by mixing in a mass ratio of 1:2 are calendered into a film by a calendering method. The calendered film is cut and then cleaned by a good ultrasonic cleaning instrument to ensure that it is dust-free and dirt-free. After cleaning, it is dried to obtain a plastic substrate as the base layer 1;

[0058] Step 2: Preparation of orientation layer

[0059] An adhesion promoter is coated on the upper surface of the base layer 1 prepared in step 1 as an adhesion layer 3, and polyimide is coated on the upper surface of the adhesion layer 3 and cured by heating to form an alignment layer 2, and then an ordered alignment structure is formed on the upper surface of the alignment layer 2 by a photo-alignment technique;

[0060] Step 3: Preparation of photosensitive layer

[0061] The photosensitive group, alcohol solvent (methanol or ethanol) and deionized water are mixed uniformly in a mass ratio of 1:5:5 to prepare a uniform photosensitive coating solution, and then the photosensitive coating solution is coated on the upper surface of the alignment layer 2 prepared in step 2 by spraying, and cured by heating to form a photosensitive layer 4, and then the photosensitive layer 4 is irradiated with ultraviolet light to activate the photosensitive group;

[0062] Step 4: Preparation of protective layer

[0063] The polyurethane, acrylic resin, ketone solvent (acetone or methyl ethyl ketone) and deionized water are mixed uniformly in a mass ratio of 1:2:5:5 to prepare a uniform protective coating solution, and then the protective coating solution is applied to the upper surface of the photosensitive layer 4 prepared in step 3 by spin coating, and is cured by drying to form a protective layer 5;

[0064] Step 5: Preparation of protective layer

[0065] Polyvinyl alcohol, polyacrylic acid and deionized water are mixed uniformly in a mass ratio of 1:2:10 to prepare a uniform surface treatment coating solution, and then the surface treatment coating solution is coated on the upper surface of the protective layer 5 prepared in step 4 by a slit coating method, and dried to form a surface treatment layer 6 after solidification, thereby obtaining a finished liquid crystal alignment film;

[0066] Step 6: Finished product annealing and post-processing

[0067] The finished liquid crystal alignment film obtained in step five is heated to 250°C at a heating rate of 20°C / min, and then kept warm for 40 minutes. Then the heating is stopped and naturally cooled to complete the annealing treatment, release the residual stress generated in the preparation process of the alignment film, improve the stability of the film, improve the crystallinity, thereby improving the mechanical strength and thermal stability of the alignment film, and comprehensively improve the microstructure and performance of the material.

[0068] The liquid crystal alignment films in Example 1 and Example 2 were subjected to a transmittance test (referring to the national standard GB / T2410-2008), a tensile strength test (referring to the national standard GB / T13022-1991) and a thermal stability test (exposing each liquid crystal alignment film sample to a high temperature environment to observe at what temperature each liquid crystal alignment film sample deforms or changes color), and a common liquid crystal alignment film (ITO alignment film) purchased on the market was used as a comparative example to undergo the same test. The test results are shown in Table 1 below:

[0069] Table 1 Test results

[0070]

[0071] It can be seen from Table 1 above that the liquid crystal alignment films of Example 1 and Example 2 of the present invention are superior to the common liquid crystal alignment films available on the market in terms of optical properties, mechanical properties and thermal stability.

[0072] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A liquid crystal alignment film structure for a foldable electronic reader, comprising a substrate layer (1) and an alignment layer (2), characterized in that: The base layer (1) is located below the orientation layer (2); an adhesive layer (3) is bonded between the upper surface of the base layer (1) and the lower surface of the orientation layer (2); a photosensitive layer (4) is coated on the side of the orientation layer (2) away from the adhesive layer (3); a protective layer (5) is coated on the side of the photosensitive layer (4) away from the orientation layer (2); a surface treatment layer (6) is coated on the side of the protective layer (5) away from the photosensitive layer (4); and the surface treatment layer (6), the protective layer (5), the photosensitive layer (4), the orientation layer (2), the adhesive layer (3) and the base layer (1) are arranged in order from top to bottom.

2. The liquid crystal alignment film structure of a foldable electronic reader according to claim 1, characterized in that: The base layer (1) is prepared by mixing polyethylene terephthalate and polyethylene naphthalate and adopting a calendering process, and the mixing mass ratio of polyethylene terephthalate to polyethylene naphthalate is 1:1-2.

3. The liquid crystal alignment film structure of a foldable electronic reader according to claim 1, characterized in that: The adhesion layer (3) is an adhesion promoter coated on the upper surface of the base layer (1), and the adhesion promoter is selected from one of a silane coupling agent and a titanate coupling agent.

4. The liquid crystal alignment film structure of a foldable electronic reader according to claim 1, characterized in that: The alignment layer (2) is made of polyimide, which is formed by the polycondensation reaction of dianhydride and diamine.

5. The liquid crystal alignment film structure of a foldable electronic reader according to claim 1, characterized in that: The photosensitive layer (4) is a photosensitive group, and the photosensitive group is selected from one of an azobenzene group and a styrene group.

6. The liquid crystal alignment film structure of a foldable electronic reader according to claim 1, characterized in that: The protective layer (5) is prepared by mixing polyurethane and acrylic resin, and the mixing mass ratio of the polyurethane to the acrylic resin is 1:1-2.

7. The liquid crystal alignment film structure of a foldable electronic reader according to claim 1, characterized in that: The surface treatment layer (6) is prepared by mixing polyvinyl alcohol and polyacrylic acid, and the mixing mass ratio of the polyvinyl alcohol to the polyacrylic acid is 1:1-2.

8. The liquid crystal alignment film structure of a foldable electronic reader according to any one of claims 1 to 7, characterized in that: The method for preparing the liquid crystal alignment film comprises the following steps: Step 1: Ethylene terephthalate and polyethylene naphthalate are mixed in a preset ratio and rolled into a film by a rolling method, and then cut and ultrasonically cleaned to obtain a plastic substrate as a base layer (1); Step 2: coating an adhesion promoter on the upper surface of the substrate layer (1) as an adhesion layer (3), then coating polyimide on the upper surface of the adhesion layer (3), and forming an alignment layer (2) after curing, and then forming an ordered alignment structure on the upper surface of the alignment layer (2) by means of a friction alignment or photo-alignment technique; Step 3: mixing a photosensitive group, an alcohol solvent and deionized water in a mass ratio of 1:5:5 to prepare a photosensitive coating solution, coating the photosensitive coating solution on the upper surface of the alignment layer (2), and forming a photosensitive layer (4) after curing, and using ultraviolet light to activate the photosensitive group; Step 4: polyurethane, acrylic resin, ketone solvent and deionized water are mixed in a mass ratio of 1:1 to 2:5:5 to prepare a protective coating solution, and the protective coating solution is then coated on the upper surface of the photosensitive layer (4), and cured to form a protective layer (5); Step 5: polyvinyl alcohol, polyacrylic acid and deionized water are mixed in a mass ratio of 1:1 to 2:10 to prepare a surface treatment coating solution, and then the surface treatment coating solution is coated on the upper surface of the protective layer (5), and after solidification, a surface treatment layer (6) is formed to obtain a finished liquid crystal alignment film; Step 6: Heat the finished liquid crystal alignment film to 200-250° C., keep the temperature for 30-40 minutes, then stop heating and cool naturally to complete the post-annealing treatment of the liquid crystal alignment film.

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