Alignment film additive, alignment film, liquid crystal display panel and manufacturing method thereof

Abstract

The present invention provides an alignment film additive, an alignment film, a liquid crystal display panel and a method for manufacturing the same. The general structural formula of the alignment film additive is #imgabs0#, wherein n is 2 to 4; A is a cycloalkyl group, a phenyl group or an ester group; Sp is H, -(CH2) m ‑,‑(CH2) m -a group in which at least one of the -CH2- is replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-O-, -OCH2-, -CH2O-, or -(CH2) m A group in which at least one H atom in the alignment film is replaced by F or Cl, wherein m is 1 to 8; B is OH or COOH; and R is a polymerizable group. When the alignment film additive is applied to the alignment film, the compactness of the alignment film can be improved, thereby preventing the impurity ions in the CF substrate and the TFT substrate from diffusing into the liquid crystal material, preventing the liquid crystal material from being contaminated by the impurity ions, thereby improving the voltage holding rate of the liquid crystal material, and further eliminating the image sticking problem of the liquid crystal display panel.

Description

Technical Field

[0001] The present application relates to the display field, and in particular to an alignment film additive, an alignment film, a liquid crystal display panel and a manufacturing method thereof. Background Art

[0002] With the development of display technology, flat display devices such as liquid crystal displays (LCD) have been widely used in various consumer electronic products such as mobile phones, televisions, personal digital assistants, digital cameras, laptops, desktop computers, etc. due to their advantages of high image quality, power saving, thin body and wide application range, becoming the mainstream among display devices.

[0003] Most of the liquid crystal display devices on the current market are backlight type liquid crystal displays, which include a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is to place liquid crystal molecules between two parallel glass substrates. There are many vertical and horizontal fine wires between the two glass substrates. The liquid crystal molecules are controlled to change direction by powering on or off, and the light from the backlight module is refracted to produce a picture.

[0004] Liquid crystal display panels are usually composed of a color filter (CF) substrate, a thin film transistor (TFT) substrate, a liquid crystal (LC) sandwiched between the color filter substrate and the thin film transistor substrate, and a sealant frame (Sealant). The CF substrate and the TFT substrate of the liquid crystal display panel are respectively provided with an alignment film, whose main function is to align the liquid crystal molecules in a certain direction. However, due to the poor density of the existing alignment film, the impurity ions in the CF substrate and the TFT substrate pass through the alignment film and diffuse into the liquid crystal material, thereby contaminating the liquid crystal material, and then reducing the voltage holding ratio (VHR) of the liquid crystal material, and finally causing the image sticking (IS) problem when the liquid crystal display panel switches the screen. Summary of the invention

[0005] The embodiments of the present application provide an alignment film additive, an alignment film, a liquid crystal display panel and a method for manufacturing the same. When the alignment film additive is applied to the alignment film, the density of the alignment film can be improved, thereby preventing impurity ions in the CF substrate and the TFT substrate from diffusing into the liquid crystal material, preventing the liquid crystal material from being contaminated by the impurity ions, thereby improving the voltage holding rate of the liquid crystal material and eliminating the image sticking problem of the liquid crystal display panel.

[0006] In a first aspect, the present invention provides an alignment film additive, the general structural formula of which is Wherein, n is 2 to 4;

[0007] A is a cycloalkyl group, a phenyl group or an ester group;

[0008] Sp is H, -(CH 2 ) m -、-(CH 2 ) m -At least one -CH 2 -By -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -OCH 2 -、-CH 2 O-substituted groups, or -(CH 2 ) m -a group in which at least one H atom is replaced by F or Cl, wherein m is 1 to 8;

[0009] B is -OH or -COOH;

[0010] R is a polymerizable group.

[0011] In some embodiments, R is tert-butyl methacrylate or tert-butyl acrylate.

[0012] In some embodiments, the alignment film additive includes at least one of compound AD1, compound AD2, compound AD3, compound AD4, compound AD5, compound AD6, compound AD7, compound AD8, compound AD9, compound AD10, compound AD11, and compound AD12; wherein,

[0013] The structural formula of the compound AD1 is

[0014] The structural formula of the compound AD2 is The structural formula of the compound AD3 is The structural formula of the compound AD4 is The structural formula of the compound AD5 is The structural formula of the compound AD6 is The structural formula of the compound AD7 is The structural formula of the compound AD8 is The structural formula of the compound AD9 is The structural formula of the compound AD10 is

[0015] The structural formula of the compound AD11 is

[0016] The structural formula of the compound AD12 is

[0017] In a second aspect, an embodiment of the present application provides an alignment film formed by copolymerization of polyimide acid and the alignment film additive as described above.

[0018] In some embodiments, the content of the alignment film additive in the alignment film is 1 wt % to 10 wt %.

[0019] In a third aspect, an embodiment of the present application provides a liquid crystal display panel, comprising:

[0020] a first substrate;

[0021] a second substrate, arranged opposite to the first substrate;

[0022] Liquid crystal material, disposed between the first substrate and the second substrate;

[0023] A first alignment film is located on a side of the first substrate facing the second substrate;

[0024] A second alignment film is located on a side of the second substrate facing the first substrate;

[0025] Wherein, the first alignment film and / or the second alignment film are both copolymerized by polyimide acid and the alignment film additive according to any one of claims 1 to 3.

[0026] In some embodiments, the thickness of the first alignment film and the thickness of the second alignment film are both 80 nm to 120 nm.

[0027] In some embodiments, the content of the alignment film additive in the first alignment film is 1 wt % to 10 wt %, and the content of the alignment film additive in the second alignment film is 1 wt % to 10 wt %.

[0028] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a liquid crystal display panel, comprising:

[0029] Providing a polyimide acid solution and the alignment film additive as described above, and mixing the polyimide acid solution and the alignment film additive to obtain a precursor solution;

[0030] Providing a first substrate and a second substrate, applying the precursor solution on both the first substrate and the second substrate, curing the precursor solution on the first substrate and the precursor solution on the second substrate, forming a first alignment film on the first substrate, and forming a second alignment film on the second substrate;

[0031] Aligning and assembling the first substrate and the second substrate, wherein the first alignment film is located on a side of the first substrate facing the second substrate, and the second alignment film is located on a side of the second substrate facing the first substrate;

[0032] A liquid crystal material is disposed between the first substrate and the second substrate to obtain a liquid crystal display panel.

[0033] In some embodiments, curing the precursor solution on the first substrate and the precursor solution on the second substrate includes:

[0034] Performing a first curing of the precursor solution on the first substrate and the precursor solution on the second substrate by heating;

[0035] The precursor solution on the first substrate and the precursor solution on the second substrate are cured for a second time by using a method of ultraviolet polarized light irradiation.

[0036] The alignment film additive provided in the embodiment of the present application can be copolymerized with polyimide acid to form an alignment film. The B group in the alignment film additive is -OH or -COOH. When the B group is -OH, -OH can react with the carboxyl group in the polyimide acid. When the B group is -COOH, -COOH can react with the amine group in the polyimide acid. Since the alignment film additive contains multiple B groups, and the multiple B groups can react with multiple polyimide acid molecules respectively, that is, one alignment film additive molecule can connect multiple polyimide molecules together, so that Improve the density of the alignment film. In addition, the R group in the alignment film additive is a polymerizable group. When the alignment film additive and the polyimide acid undergo copolymerization reaction, the R group can also be further polymerized, thereby further improving the density of the alignment film. It can be understood that since the alignment film containing the above-mentioned alignment film additive has a higher density, it can block the impurity ions in the CF substrate and the TFT substrate from diffusing into the liquid crystal material, thereby avoiding the liquid crystal material from being contaminated by impurity ions, thereby improving the voltage holding rate of the liquid crystal material and eliminating the afterimage problem of the liquid crystal display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0038] Figure 1 Schematic diagram of the synthesis process of compound AD1 provided in the examples of the present application.

[0039] Figure 2 A schematic diagram of the structure of a liquid crystal display panel provided in an embodiment of the present application.

[0040] Figure 3 A flow chart of a method for manufacturing a liquid crystal display panel provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0042] The present application embodiment provides an alignment film additive, the general structural formula of which is Wherein, n is 2 to 4 (e.g., 2, 3, 4);

[0043] A is a cycloalkyl group, a phenyl group or an ester group;

[0044] Sp is H, -(CH 2 ) m -、-(CH 2 ) m -At least one -CH 2 -By -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -OCH 2 -、-CH 2 O-substituted groups, or -(CH 2 ) m -a group in which at least one H atom is replaced by F or Cl, wherein m is 1 to 8 (e.g., 1, 2, 3, 4, 5, 6, 7, 8);

[0045] B is -OH or -COOH;

[0046] R is a polymerizable group.

[0047] Illustratively, R is a tert-butyl methacrylate group or a tert-butyl acrylate group.

[0048] Exemplarily, the alignment film additive may include at least one of compound AD1, compound AD2, compound AD3, compound AD4, compound AD5, compound AD6, compound AD7, compound AD8, compound AD9, compound AD10, compound AD11, and compound AD12; wherein,

[0049] The structural formula of compound AD1 is

[0050] The structural formula of compound AD2 is

[0051] The structural formula of compound AD3 is

[0052] The structural formula of compound AD4 is

[0053] The structural formula of compound AD5 is

[0054] The structural formula of compound AD6 is

[0055] The structural formula of compound AD7 is

[0056] The structural formula of compound AD8 is

[0057] The structural formula of compound AD9 is

[0058] The structural formula of compound AD10 is

[0059] The structural formula of compound AD11 is

[0060] The structural formula of compound AD12 is

[0061] See also Figure 1 , Figure 1 Schematic diagram of the synthesis process of compound AD1 provided in the embodiments of the present application. The synthesis method of compound AD1 may include:

[0062] Under a nitrogen atmosphere, 5 mmol CHEP (1,4-cyclohexanedimethanol diglycidyl ether), 11 mmol AA (acrylic acid), 0.025 mmol inhibitor BHT (2,6-di-tert-butyl-p-cresol), 0.05 mmol catalyst TBPB (tert-butyl perbenzoate) and a certain amount of solvent PGMEA (propylene glycol methyl ether acetate) were mixed together (the solid content in the mixture was 40 wt%), and magnetically stirred (600 rpm) at 110°C for 3 hours to obtain the final product - compound AD1.

[0063] The alignment film additive provided in the embodiment of the present application can be copolymerized with polyimide acid to form an alignment film. The B group in the alignment film additive is -OH or -COOH. When the B group is -OH, -OH can react with the carboxyl group in the polyimide acid. When the B group is -COOH, -COOH can react with the amine group in the polyimide acid. Since the alignment film additive contains multiple B groups, and the multiple B groups can react with multiple polyimide acid molecules respectively, that is, one alignment film additive molecule can connect multiple polyimide molecules together, so that Improve the density of the alignment film. In addition, the R group in the alignment film additive is a polymerizable group. When the alignment film additive and the polyimide acid undergo copolymerization reaction, the R group can also be further polymerized, thereby further improving the density of the alignment film. It can be understood that since the alignment film containing the above-mentioned alignment film additive has a higher density, it can block the impurity ions in the CF substrate and the TFT substrate from diffusing into the liquid crystal material, thereby avoiding the liquid crystal material from being contaminated by impurity ions, thereby improving the voltage holding rate of the liquid crystal material and eliminating the afterimage problem of the liquid crystal display panel.

[0064] The embodiment of the present application further provides an alignment film, which is copolymerized by polyimide acid and the alignment film additive in any of the above embodiments.

[0065] Illustratively, the content of the alignment film additive in the alignment film is 1 wt % to 10 wt %, for example, 1 wt %, 3 wt %, 5 wt %, 7 wt %, 10 wt %, and the like.

[0066] See also Figure 2 , Figure 2 A schematic diagram of the structure of a liquid crystal display panel provided in an embodiment of the present application. The embodiment of the present application also provides a liquid crystal display panel 100, comprising a first substrate 10, a second substrate 20, a liquid crystal material 40, a first alignment film 31, and a second alignment film 32, wherein the first substrate 10 and the second substrate 20 are arranged opposite to each other, the liquid crystal material 40 is arranged between the first substrate 10 and the second substrate 20, the first alignment film 31 is located on a side of the first substrate 10 facing the second substrate 20, and the second alignment film 32 is located on a side of the second substrate 20 facing the first substrate 10.

[0067] The first alignment film 31 and / or the second alignment film 32 are both copolymerized by polyimide acid and the alignment film additive in any of the above embodiments.

[0068] The performance test of the liquid crystal display panel 100 of the embodiment of the present application and the traditional liquid crystal display panel is carried out, wherein the liquid crystal display panel 100 of the embodiment of the present application is as follows: Figure 2As shown, the first alignment film 31 and the second alignment film 32 are both copolymerized by polyimide acid and an alignment film additive (compound AD1), and the content of the alignment film additive in the first alignment film 31 and the second alignment film 32 is 1wt%. The materials of the first alignment film and the second alignment film in the conventional liquid crystal display panel are both polyimide (PI). The test results show that the voltage holding ratio (VHR) of the liquid crystal display panel 100 of the embodiment of the present application is 98.9%, while the voltage holding ratio (VHR) of the conventional liquid crystal display panel is 94.5%. It can be seen that compared with the conventional liquid crystal display panel, the liquid crystal display panel 100 of the embodiment of the present application has a higher voltage holding ratio. In addition, the liquid crystal display panel 100 of the embodiment of the present application basically does not have an afterimage phenomenon when switching the screen, while the conventional liquid crystal display panel has a more serious afterimage phenomenon when switching the screen.

[0069] Exemplarily, the thickness of the first alignment film 31 and the thickness of the second alignment film 32 are both 80 nm to 120 nm, for example, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, etc.

[0070] Illustratively, the content of the alignment film additive in the first alignment film 31 is 1 wt % to 10 wt %, for example, 1 wt %, 3 wt %, 5 wt %, 7 wt %, 10 wt %, and the like.

[0071] Illustratively, the content of the alignment film additive in the second alignment film 32 is 1 wt % to 10 wt %, for example, 1 wt %, 3 wt %, 5 wt %, 7 wt %, 10 wt %, etc.

[0072] See also Figure 3 , Figure 3 Flow chart of a method for manufacturing a liquid crystal display panel provided in an embodiment of the present application. The present application also provides a method for manufacturing a liquid crystal display panel, which can be used to manufacture the liquid crystal display panel 100 in any of the above embodiments, and the manufacturing method may include:

[0073] S100, providing a polyimide acid solution and an alignment film additive in any of the above embodiments, and mixing the polyimide acid solution and the alignment film additive to obtain a precursor solution.

[0074] Exemplarily, "providing a polyimide acid solution" may specifically include: mixing 6.1072 g of 1,2-bis(4-aminophenoxy)ethane, 2.7035 g of p-phenylenediamine, and 133 mL of solvent NMP (N-methylpyrrolidone) in a three-necked flask, and after the solid is fully dissolved, adding 9.8055 g of cyclobutanetetracarboxylic dianhydride to the three-necked flask, and reacting at room temperature for 24 hours to obtain a polyimide acid (PAA) solution.

[0075] In the embodiments of the present application, room temperature refers to 10°C to 30°C, for example, 10°C, 15°C, 20°C, 25°C, 30°C, etc.

[0076] Exemplarily, “mixing the polyimide acid solution and the alignment film additive to obtain a precursor solution” may specifically include:

[0077] 50 g of the polyimide acid solution, 50 g of ethylene glycol monobutyl ether and 0.5 g of compound AD1 were mixed evenly to obtain a precursor solution containing compound AD1 (alignment film additive).

[0078] S200, please combine Figure 2 , provide a first substrate 10 and a second substrate 20, apply a precursor solution on both the first substrate 10 and the second substrate 20, solidify the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20, form a first alignment film 31 on the first substrate 10, and form a second alignment film 32 on the second substrate 20.

[0079] In some embodiments, the first substrate 10 is a CF (color film) substrate, and the second substrate 20 is a TFT (thin film transistor) substrate; in some embodiments, the first substrate 10 is a TFT substrate, and the second substrate 20 is a CF substrate.

[0080] Exemplarily, an ITO (Indium Tin Oxide) electrode is disposed on a surface of one of the first substrate 10 and the second substrate 20 , and an ITO electrode is not disposed on a surface of the other of the first substrate 10 and the second substrate 20 .

[0081] For example, the shapes of the first substrate 10 and the second substrate 20 may both be square, and the sizes of the first substrate 10 and the second substrate 20 may both be 10 cm*10 cm.

[0082] Illustratively, before curing the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20, the first substrate 10 and the second substrate 20 can be baked at 70°C to 90°C (for example, 70°C, 80°C, 90°C, etc.) for 3 minutes to 7 minutes (for example, 3 minutes, 5 minutes, 7 minutes, etc.) to volatilize the solvent in the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20.

[0083] Exemplarily, “curing the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20” may specifically include:

[0084] The precursor solution on the first substrate 10 and the precursor solution on the second substrate 20 are first cured by heating;

[0085] The precursor solution on the first substrate 10 and the precursor solution on the second substrate 20 are cured for the second time by irradiating with polarized ultraviolet light.

[0086] It should be noted that when ultraviolet polarized light is used to irradiate the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20, the ultraviolet polarized light can not only further polymerize the R group (polymerizable group) in the alignment film additive, thereby achieving a second solidification of the precursor solution and further improving the density of the first alignment film 31 and the second alignment film 32, but also the ultraviolet polarized light can cause the polyimide molecules whose arrangement direction is parallel to the polarization direction of the ultraviolet polarized light to break. For example, when the ultraviolet polarized light is vertically polarized light, the polyimide molecules arranged in the vertical direction will break under the action of ultraviolet light, while the polyimide molecules arranged in the horizontal direction will not be affected. Therefore, the horizontally arranged polyimide molecules retained in the first alignment film 31 and the second alignment film 32 can guide the liquid crystal molecules in the liquid crystal material 40 to be arranged in the horizontal direction, thereby achieving horizontal alignment.

[0087] Exemplarily, "using a heating method to perform a first curing on the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20" may specifically include: baking the first substrate 10 and the second substrate 20 at 210°C to 250°C (for example, 210°C, 220°C, 230°C, 240°C, 250°C, etc.) for 20 minutes to 40 minutes (for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.).

[0088] For example, “second curing the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20 by using ultraviolet polarized light irradiation” may specifically include: irradiating the precursor solution on the first substrate 10 and the precursor solution on the second substrate 20 with ultraviolet polarized light having a wavelength of 320 nm, and the illumination of the ultraviolet polarized light may be 200 W / cm 2 , the total light quantity is 550Mj / cm 2 .

[0089] Exemplarily, the thickness of the first alignment film 31 and the thickness of the second alignment film 32 are both 80 nm to 120 nm, for example, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, etc.

[0090] S300, please combine Figure 2 The first substrate 10 and the second substrate 20 are aligned and combined, the first alignment film 31 is located on the side of the first substrate 10 facing the second substrate 20, and the second alignment film 32 is located on the side of the second substrate 20 facing the first substrate 10.

[0091] Exemplarily, “aligning and combining the first substrate 10 and the second substrate 20” may specifically include:

[0092] Applying a sealant 50 on one surface of the first substrate 10 and the second substrate 20;

[0093] The first substrate 10 and the second substrate 20 are aligned and assembled, and the first substrate 10 and the second substrate 20 are connected by using a sealant 50 . The first substrate 10 , the second substrate 20 and the sealant together enclose an accommodation space for accommodating the liquid crystal material 40 .

[0094] S400, please combine Figure 2 A liquid crystal material 40 is disposed between the first substrate 10 and the second substrate 20 to obtain a liquid crystal display panel 100 .

[0095] For example, the liquid crystal material 40 may be disposed between the first substrate 10 and the second substrate 20 by vacuum injection of liquid crystal.

[0096] For example, the liquid crystal display panel 100 may be a horizontal alignment liquid crystal display panel, that is, liquid crystal molecules in the liquid crystal display panel 100 are arranged in a plane parallel to the first substrate 10 and the second substrate 20 .

[0097] The above is a detailed introduction to the alignment film additive, alignment film, liquid crystal display panel and its manufacturing method provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. An alignment film, characterized in that: It is copolymerized by polyimide acid and alignment film additives; The alignment film additive is compound AD1; wherein, The structural formula of the compound AD1 is 2. The alignment film according to claim 1, characterized in that: The content of the alignment film additive in the alignment film is 1 wt % to 10 wt %.

3. A liquid crystal display panel, characterized in that: include: a first substrate; a second substrate, arranged opposite to the first substrate; Liquid crystal material, disposed between the first substrate and the second substrate; A first alignment film is located on a side of the first substrate facing the second substrate; A second alignment film is located on a side of the second substrate facing the first substrate; Wherein, the first alignment film and / or the second alignment film is the alignment film as described in any one of claims 1-2.

4. The liquid crystal display panel according to claim 3, characterized in that: The thickness of the first alignment film and the thickness of the second alignment film are both 80 nm to 120 nm.

5. The liquid crystal display panel according to claim 3, characterized in that: The content of the alignment film additive in the first alignment film is 1 wt % to 10 wt %, and the content of the alignment film additive in the second alignment film is 1 wt % to 10 wt %.

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