Polarizer, preparation method thereof, display module and display equipment

Abstract

The invention discloses a polaroid and a preparation method thereof, a display module and display equipment, and relates to the technical field of display, the polaroid comprises a polarizing film, and the polarizing film comprises a PVA layer and quantum dots; at least one surface of the PVA layer contains free hydroxyl; the quantum dots are combined with organic ligands and are cross-linked with free hydroxyl groups through the organic ligands. On the basis of not additionally increasing the thickness of the film layer, the quantum dot polaroid is obtained, and the contradiction between the light and thin requirements of display equipment and the improvement of the optical performance is effectively overcome.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a polarizer and a preparation method thereof, a display module, and a display device. Background Art

[0002] As the core optical element of the liquid crystal display module, the function of the polarizer is to convert the incident light into polarized light in a specific direction to achieve image resolution. Conventional polarizers adopt a "sandwich structure", with polyvinyl alcohol (PVA) film as the core polarizing film, triacetyl cellulose (TAC) film on both sides as support and protection, and supplemented with functional layers such as pressure-sensitive adhesive and release film to achieve selective light transmission. With the upgrading of display technology's demand for color gamut and brightness, quantum dot technology has been introduced into the polarizer system due to its narrow half-wave width characteristics, forming quantum dot polarizers.

[0003] In conventional technology, the solution of superimposing an independent quantum dot film layer on the polarizer structure is often adopted. However, this stacked structure increases the total thickness of the polarizer by about 20 to 30 μm, which is contrary to the trend of thinner and lighter display devices. At the same time, the multi-layer interface is also prone to light scattering and refraction loss, affecting optical uniformity. Summary of the invention

[0004] The main purpose of the embodiments of the present application is to provide a polarizer and a preparation method thereof, a display module, and a display device, so as to obtain a quantum dot polarizer without increasing the thickness of the film layer, thereby effectively overcoming the contradiction between the demand for thinner and lighter display devices and the improvement of optical performance.

[0005] To achieve the above object, the present application provides a polarizer, the polarizer includes a polarizing film, the polarizing film includes a PVA layer and quantum dots;

[0006] At least one surface of the PVA layer contains free hydroxyl groups;

[0007] The quantum dots are combined with organic ligands and cross-linked with the free hydroxyl groups through the organic ligands.

[0008] In one embodiment, the polarizer further comprises: a first supporting layer, a second supporting layer, a first protective layer and a second protective layer;

[0009] The first supporting layer and the second supporting layer are respectively arranged on both sides of the polarizing film, the first protective layer is arranged on a side of the first supporting layer away from the polarizing film, and the second protective layer is arranged on a side of the second supporting layer away from the polarizing film.

[0010] In one embodiment, the organic ligand includes at least one of a mercaptocarboxylic acid ligand, an aminosilane ligand, an isocyanate ligand and a phosphate ligand.

[0011] In one embodiment, the organic ligand includes at least one of thioglycolic acid, mercaptopropionic acid, mercaptoalanine, mercaptoundecanoic acid, 3-aminopropyltrimethoxysilane, 3-glycidyloxysilane, hexamethylene diisocyanate, isophorone diisocyanate, triethyl phosphate and methacrylic acid phosphate.

[0012] In one embodiment, the PVA layer is a film layer obtained by dyeing and stretching.

[0013] In one embodiment, the dye used in the dyeing comprises iodine and / or iodide;

[0014] And / or, the stretching ratio of the PVA layer is 3.7 to 4.6 times.

[0015] In one embodiment, the content of iodine in the dye is: 0.4-1wt.%;

[0016] And / or, the content of iodide in the dye is: 1-1.5wt.%.

[0017] In addition, to achieve the above purpose, the present application also provides a method for preparing a polarizer, which is used to prepare the above polarizer, comprising the following steps:

[0018] Provide PVA base film;

[0019] Dyeing and stretching the PVA base film to obtain a PVA layer, wherein at least one surface of the PVA layer contains free hydroxyl groups;

[0020] The PVA layer is immersed in a quantum dot solution to obtain a polarizing film and a polarizing plate, wherein the quantum dots in the quantum dot solution are combined with organic ligands and are cross-linked with the free hydroxyl groups through the organic ligands.

[0021] In addition, to achieve the above-mentioned purpose, an embodiment of the present application further provides a display module, which includes: the polarizer as described above.

[0022] In addition, to achieve the above-mentioned purpose, an embodiment of the present application further provides a display device, which includes: the polarizer as described above.

[0023] One or more technical solutions proposed in the embodiments of the present application have at least the following technical effects: providing a polarizer, including a polarizing film, and the polarizing film includes a PVA layer and quantum dots; at least one surface of the PVA layer of the polarizing film contains free hydroxyl groups, and the quantum dots are combined with organic ligands, and then the combination of quantum dots and the PVA layer can be achieved through the cross-linking of organic ligands and free hydroxyl groups, thereby obtaining a quantum dot polarizer without increasing the thickness of the film layer, so that the polarizer has both polarizing effect and quantum dot effect, and effectively overcomes the contradiction between the demand for thinner display devices and the improvement of optical performance. In addition, after the quantum dots are embedded in the PVA layer, a homogeneous composite structure is formed, which can effectively avoid the sudden change of the refractive index of the multi-layer interface, reduce the interface light scattering loss, and improve the optical uniformity and color purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the molecular formula of PVA involved in the embodiment of the present application;

[0025] Figure 2 Schematic diagram of the molecular structure of PVA after dyeing and stretching involved in the embodiment of the present application Figure 1 ;

[0026] Figure 3 Schematic diagram of the molecular structure of PVA after dyeing and stretching involved in the embodiment of the present application Figure 2 ;

[0027] Figure 4 This is a schematic diagram of the molecular structure of PVA after combining with quantum dots involved in the embodiment of the present application;

[0028] Figure 5 This is a schematic diagram of the structure of the polarizer involved in the embodiment of the present application;

[0029] Figure 6 This is a flow chart of a method for preparing a polarizer according to an embodiment of the present application;

[0030] Figure 7 This is a conventional polarizer process flow chart;

[0031] Figure 8 This is a process flow chart of the polarizer involved in the embodiment of the present application;

[0032] Fig. 9 It is a schematic diagram of the structure of the display module involved in the embodiment of the present application.

[0033] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings.

[0034] Description of Reference Numerals

[0035] 110, polarizing film; 120, first supporting layer; 130, second supporting layer;

[0036] 140, a first protective film; 150, a second protective film;

[0037] 210, back plate; 220, light source; 230, diffusion plate;

[0038] 240, a first polarizer; 250, a liquid crystal glass; 260, a second polarizer. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0040] Hereinafter, the polarizer and its preparation method, display module, and display device of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0041] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0042] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0043] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0044] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and understandable, the technical solution of the present application is further described below in conjunction with the accompanying drawings and embodiments. However, the present application is not limited to the listed embodiments, and should also include any other known changes within the scope of the rights claimed in the present application.

[0045] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0046] In conventional technology, the solution of stacking independent quantum dot film layers on the polarizer structure is often adopted. However, this stacked structure increases the total thickness of the polarizer by about 20 to 30um, which is contrary to the trend of thinner and lighter display devices. The multi-layer interface is also prone to light scattering and refraction loss, affecting optical uniformity. In addition, the preparation time of this multi-layer polarizer film is also prolonged, increasing production costs.

[0047] The embodiment of the present application provides a polarizer, including a polarizing film, and the polarizing film includes a PVA layer and quantum dots; at least one surface of the PVA layer of the polarizing film contains free hydroxyl groups, and the quantum dots are combined with organic ligands, and then the combination of the quantum dots and the PVA layer can be achieved through the cross-linking of the organic ligands and the free hydroxyl groups, so that a quantum dot polarizer is obtained without increasing the thickness of the film layer, so that the polarizer has both polarization and quantum dot effects, and effectively overcomes the contradiction between the demand for thinner display devices and the improvement of optical performance. In addition, after the quantum dots are embedded in the PVA layer, a homogeneous composite structure is formed, which can effectively avoid the sudden change of the refractive index of the multi-layer interface, reduce the interface light scattering loss, and improve the optical uniformity and color purity.

[0048] A first aspect of an embodiment of the present application provides a polarizer, the polarizer includes a polarizing film, and the polarizing film includes a PVA layer and quantum dots;

[0049] At least one surface of the PVA layer contains free hydroxyl groups;

[0050] The quantum dots are bound to organic ligands and cross-linked with free hydroxyl groups through the organic ligands.

[0051] In a feasible embodiment, the PVA layer is a film layer made of polyvinyl alcohol (PVA). PVA has high transparency, high ductility, good iodine adsorption and excellent film-forming properties. The PVA base film adsorbs dichroic molecules (e.g., iodine molecules) and is stretched and oriented to arrange the iodine molecules in an orderly manner, thereby achieving the polarization function. Figure 1 It can be seen that the PVA molecular chain also contains a large number of hydroxyl groups (-OH). Therefore, the surface of the PVA base film contains some free hydroxyl groups that do not form hydrogen bonds with other molecules.

[0052] In a feasible embodiment, the PVA layer is a film layer obtained by dyeing and stretching.

[0053] Optionally, the dye used in dyeing includes iodine and / or iodide, and the iodide includes potassium iodide.

[0054] Optionally, the number of free hydroxyl groups on the surface of the PVA base film may be small, and in order to improve the bonding effect between the PVA base film and the quantum dots, the number of free hydroxyl groups can be further increased. Therefore, the PVA base film can be dyed with iodine solution and stretched. The PVA molecular structure of the PVA layer obtained after dyeing and stretching can be referred to Figure 2 and 3 , PVA forms a molecular structure similar to a tunnel, with iodine molecules distributed inside the tunnel and more free hydroxyl groups outside the tunnel. During the dyeing process, the iodine in the dye will penetrate into the PVA crystal to form a PVA-I eutectic. This eutectic structure can be understood as the iodine molecules embedded in the gaps formed by the arrangement of the PVA molecular chains, so a morphology similar to a "tunnel" is formed; and, as the concentration of the iodine solution increases, the hydrogen bonding effect between the PVA molecules weakens, and the destruction of the hydrogen bond network may cause the hydroxyl groups (-OH) originally connected by hydrogen bonds to lose their interaction sites, thereby forming free hydroxyl groups. Further, stretching orients the molecular chains, further destroying the local hydrogen bonds. At the same time, stretching may also expand the defective areas of the PVA crystals, promote iodine penetration, and indirectly aggravate the freeing of hydroxyl groups. In other words, in the original PVA base film, in the original PVA film, the hydroxyl groups mainly form a cross-linked network through hydrogen bonds, but not all hydroxyl groups are involved in bonding, so there will be a small amount of free hydroxyl groups; and by dyeing and stretching, the proportion of free hydroxyl groups can be effectively increased, so that they can be better combined with quantum dots.

[0055] Optionally, the stretching ratio of the PVA layer is 3.7 to 4.6 times, for example, the stretching ratio of the PVA layer is 3.7 times, 3.8 times, 3.9 times, 4 times, 4.1 times, 4.2 times, 4.3 times, 4.4 times, 4.5 times, 4.6 times, etc. If the stretching ratio is too small, the iodine complex in the PVA layer may not be sufficiently aligned, thereby reducing the polarization degree of the polarizer, which is a key indicator for measuring the performance of the polarizer. Too low a polarization degree will reduce the contrast of the display panel; further, the insufficient stretching ratio may also affect the transmittance of the polarizer, resulting in insufficient display brightness, affecting the user experience, and / or making the cross-linking structure of the PVA layer not tight enough, reducing the moisture and heat resistance of the polarizer, and easily failing in high humidity and high temperature environments. If the stretching ratio is too high, it may also cause uneven thickness distribution of the PVA layer, or even cracks, affecting the product yield; further, although a high stretching ratio can theoretically improve the degree of polarization, a too high stretching ratio may also cause excessive internal stress in the PVA layer, which in turn reduces optical uniformity and even produces rainbow lines or haze problems. Therefore, the present application embodiment determines that the stretching ratio of the PVA layer is 3.7 to 4.6 times.

[0056] Optionally, the iodine content in the dye is: 0.4~1wt.%; for example, the iodine content in the dye is: 0.4wt.%, 0.45wt.%, 0.5wt.%, 0.55wt.%, 0.6wt.%, 0.65wt.%, 0.7wt.%, 0.75wt.%, 0.8wt.%, 0.85wt.%, 0.9wt.%, 0.95wt.%, 1wt.%, etc.

[0057] Optionally, the iodide content in the dye is: 1 to 1.5 wt.%; for example, the iodide content in the dye is: 1 wt.%, 1.1 wt.%, 1.15 wt.%, 1.2 wt.%, 1.25 wt.%, 1.3 wt.%, 1.35 wt.%, 1.4 wt.%, 1.45 wt.%, 1.5 wt.%, etc.

[0058] Optionally, the dye includes iodine and potassium iodide, wherein the content of iodine is 0.4-1wt.%, and the content of potassium iodide is 1-1.5wt.%. Iodine can compete with the hydroxyl groups of PVA for binding sites and destroy the original hydrogen bond network. When the iodine concentration increases, its interaction with the hydroxyl groups is enhanced, resulting in more hydrogen bond breaks, thereby producing more free hydroxyl groups, while low concentrations of iodine may only partially destroy hydrogen bonds, resulting in fewer free hydroxyl groups on the surface of the PVA layer. Therefore, the embodiment of the present application accurately controls the amount of free hydroxyl groups generated by controlling the iodine content in the dye, thereby achieving regulation of the content of quantum dots in the polarizer.

[0059] In one feasible embodiment, quantum dots have the characteristic of high color purity luminescence. Therefore, by adding quantum dots to the polarizing film of the display device, the color gamut performance of the display device can be significantly improved. The 360-degree indifferent radiation fluorescence characteristics of quantum dots can also improve the color performance of the display device at a wide viewing angle, so that the picture can still maintain high brightness and high color gamut at different angles. In order to achieve the combination of quantum dots and the PVA layer, the embodiment of the present application combines quantum dots with organic ligands, and the organic ligands usually have functional groups (such as carboxylic acid groups, amino groups, thiol groups, hydroxyl groups, etc.), which can react with the free hydroxyl groups on the surface of the PVA layer (such as condensation, esterification or silane coupling) to achieve cross-linking, thereby enabling the combination of quantum dots (QD) and the PVA layer. The molecular structure of PVA after combining with quantum dots is shown in FIG. Figure 4 .

[0060] Optionally, the crosslinking between the organic ligand and the free hydroxyl group refers to the formation of a covalent bond between the organic ligand of the quantum dot and the free hydroxyl group (-OH) on the surface of the PVA layer through a chemical reaction, and the specific reaction type depends on the terminal group of the ligand and may include: silane coupling reaction, esterification reaction, condensation reaction, epoxy ring-opening reaction, etc.

[0061] Optionally, the combination of quantum dots and organic ligands can be achieved through ligand exchange, in situ modification, etc., where ligand exchange refers to a method of replacing the original ligand on the surface of quantum dots with a functional ligand through a chemical reaction, and in situ modification is a method of directly introducing functional ligands during the synthesis of quantum dots so that they are synchronously combined with the surface of quantum dots.

[0062] Exemplarily, quantum dots are dispersed in a solvent, an excess of organic ligand material is added and stirred, the pH is adjusted to promote the coordination of organic ligands with metal ions on the surface of quantum dots, and unreacted organic ligand material and original ligands are removed by centrifugation or dialysis to obtain quantum dots bound with organic ligands.

[0063] Optionally, the quantum dots are water-soluble quantum dots, so that in the process of preparing the polarizing film, the quantum dots combined with organic ligands are dissolved in an aqueous solution to obtain a quantum dot solution, and then the PVA layer is immersed in the quantum dot solution, so that the preparation of the polarizing film can be quickly achieved.

[0064] Optionally, during the preparation of the polarizing film, a target solvent that can dissolve quantum dots can be selected, and the quantum dots combined with organic ligands can be dissolved in the target solvent to obtain a quantum dot solution. The PVA layer can then be immersed in the quantum dot solution to quickly prepare the polarizing film.

[0065] Optionally, the quantum dots include: red light quantum dots and / or green light quantum dots.

[0066] Optionally, the quantum dots include: at least one of: II-VI group compounds (e.g., cadmium sulfide, cadmium selenide, cadmium telluride, zinc selenide, etc.), III-V group compounds (e.g., indium phosphide, indium arsenide, etc.), IV-VI group compounds (e.g., lead sulfide, lead selenide, etc.) and perovskite quantum dots (e.g., CsPbI3, etc.).

[0067] In a feasible embodiment, the organic ligand includes at least one of a mercaptocarboxylic acid ligand, an aminosilane ligand, an isocyanate ligand and a phosphate ligand.

[0068] Optionally, the mercaptocarboxylic acid ligand includes at least one of thioglycolic acid, mercaptopropionic acid, mercaptoalanine and mercaptoundecanoic acid.

[0069] Optionally, the aminosilane ligand includes at least one of 3-aminopropyltrimethoxysilane and 3-glycidyloxysilane.

[0070] Optionally, the isocyanate ligand includes at least one of hexamethylene diisocyanate and isophorone diisocyanate.

[0071] Optionally, the phosphate ligand includes triethyl phosphate and / or methacrylate phosphate.

[0072] Illustratively, the organic ligand includes at least one of thioglycolic acid, mercaptopropionic acid, mercaptoalanine and mercaptoundecanoic acid.

[0073] Exemplarily, the cross-linking between PVA and thioglycolic acid is an esterification reaction, and the reaction formula is as follows:

[0074]

[0075] It can be seen that the combination of quantum dots and PVA can be achieved through the cross-linking between the above-mentioned organic ligands and the free hydroxyl groups contained in at least one surface of the PVA layer.

[0076] In one possible implementation, in one possible implementation, referring to Figure 5 , polarizers also include:

[0077] The first supporting layer 120 and the second supporting layer 130 are respectively disposed on two sides of the polarizing film 110;

[0078] A first protective film 140 is disposed on a side of the first supporting layer 120 away from the polarizing film 110;

[0079] The second protective film 150 is disposed on a side of the second supporting layer 130 away from the polarizing film 110 .

[0080] Optionally, the protective film (ie, the first protective film and the second protective film) is the outermost layer that protects the polarizer, and can prevent the internal film surface of the polarizer from being physically damaged (such as scratches, dust, etc.).

[0081] Optionally, the material of the protective film includes: polyethylene and / or polyethylene terephthalate.

[0082] Optionally, the surface of the protective film may be further coated with an anti-scratch layer (eg, polyvinyl alcohol or silicon dioxide) and / or an anti-dust layer.

[0083] Optionally, in order to enable the polarizer to be bonded to the structure of the display module, a pressure-sensitive adhesive layer can be provided on the surface of the first protective film and / or the second protective film on the side away from the polarizing film, and in order to protect the pressure-sensitive adhesive layer from damage and avoid the generation of bubbles during bonding, a release film can be provided on the surface of the pressure-sensitive adhesive layer on the side away from the polarizing film.

[0084] Optionally, the first supporting layer and / or the second supporting layer are used to support the polarizing film to prevent the polarizing film from shrinking, while isolating moisture and air to protect the polarizing film from hydrolysis and ultraviolet damage.

[0085] Optionally, the material of the first supporting layer and / or the second supporting layer includes: triacetyl cellulose (TAC), which has good optical uniformity and transparency.

[0086] In this embodiment, a polarizer is provided, including a polarizing film, and the polarizing film includes a PVA layer and quantum dots; at least one surface of the PVA layer of the polarizing film contains free hydroxyl groups, and the quantum dots are combined with organic ligands, and then the combination of the quantum dots and the PVA layer can be achieved through the cross-linking of the organic ligands and the free hydroxyl groups, so that a quantum dot polarizer is obtained without increasing the thickness of the film layer, so that the polarizer has both polarization and quantum dot effects, and effectively overcomes the contradiction between the demand for thinner display devices and the improvement of optical performance. In addition, after the quantum dots are embedded in the PVA layer, a homogeneous composite structure is formed, which can effectively avoid the sudden change of the refractive index of the multi-layer interface, reduce the interface light scattering loss, and improve the optical uniformity and color purity.

[0087] The second aspect of the present application provides a method for preparing a polarizing film, referring to Figure 6 , used to prepare the polarizing film as described above. The polarizing film preparation method comprises the following steps:

[0088] Step S10, providing a PVA base film;

[0089] In one possible embodiment, a PVA base film for preparing a polarizing film is provided.

[0090] Optionally, the PVA base film can be obtained by unwinding and swelling.

[0091] Optionally, the unwinding step includes: unwinding the rolled PVA from a reel and entering the production line.

[0092] Optionally, the swelling step includes: swelling the PVA with deionized water and / or a weak alkaline solution (such as NaOH), thereby increasing the voids in the membrane to facilitate subsequent dyeing and adsorption of iodine molecules. Optionally, the swelling temperature is 30-50° C., and the time is 1-3 minutes.

[0093] Step S20, dyeing and stretching the PVA base film to obtain a PVA layer, wherein at least one surface of the PVA layer contains free hydroxyl groups;

[0094] In a feasible embodiment, the PVA base film is dyed and stretched to obtain at least one PVA layer having a surface rich in free hydroxyl groups.

[0095] Optionally, the dyeing step includes: immersing the PVA base film in a dye, wherein the dye includes iodine and / or iodide; for example, the dye includes a mixed solution made of iodine solution and potassium iodide. During the dyeing process, the iodine in the dye will penetrate into the PVA crystal to form a PVA-I eutectic. This eutectic structure can be understood as iodine molecules embedded in the gaps formed by the arrangement of PVA molecular chains, so a morphology similar to a "tunnel" is formed; and as the concentration of the iodine solution increases, the hydrogen bonding effect between PVA molecules is weakened, and the destruction of the hydrogen bonding network may cause the hydroxyl groups (-OH) originally connected by hydrogen bonds to lose their interaction sites, thereby forming free hydroxyl groups.

[0096] Optionally, the iodine content in the dye is 0.4-1wt.%. For example, the iodine content in the dye is 0.4wt.%, 0.45wt.%, 0.5wt.%, 0.55wt.%, 0.6wt.%, 0.65wt.%, 0.7wt.%, 0.75wt.%, 0.8wt.%, 0.85wt.%, 0.9wt.%, 0.95wt.%, 1wt.%, etc.

[0097] Optionally, the iodide content in the dye is: 1 to 1.5 wt.%; for example, the iodide content in the dye is: 1 wt.%, 1.1 wt.%, 1.15 wt.%, 1.2 wt.%, 1.25 wt.%, 1.3 wt.%, 1.35 wt.%, 1.4 wt.%, 1.45 wt.%, 1.5 wt.%, etc.

[0098] Optionally, the dye includes iodine and potassium iodide, wherein the content of iodine is 0.4-1wt.%, and the content of potassium iodide is 1-1.5wt.%. Iodine can compete with the hydroxyl groups of PVA for binding sites and destroy the original hydrogen bond network. When the iodine concentration increases, its interaction with the hydroxyl groups is enhanced, resulting in more hydrogen bond breaks, thereby producing more free hydroxyl groups, while low concentrations of iodine may only partially destroy hydrogen bonds, resulting in fewer free hydroxyl groups on the surface of the PVA layer. Therefore, the embodiment of the present application accurately controls the amount of free hydroxyl groups generated by controlling the iodine content in the dye, thereby achieving regulation of the content of quantum dots in the polarizing film.

[0099] Optionally, water washing can be performed after dyeing to remove residual dye on the surface of the membrane layer to prevent impurities from interfering with subsequent stretching and color touch-up; optionally, multi-stage countercurrent water washing can be performed to ensure thorough cleaning.

[0100] Optionally, the stretching step includes: stretching the PVA base film in a fixed direction to orient the iodine complex to form an anisotropic structure. The molecular chains are oriented by stretching, further destroying the local hydrogen bonds. At the same time, stretching may also expand the defective area of ​​the PVA crystal, promote iodine penetration, and indirectly aggravate the freeing of hydroxyl groups.

[0101] Optionally, the stretching ratio of the PVA layer in the stretching step is 3.7 to 4.6 times that of the PVA base film. For example, the stretching ratio of the PVA layer is 3.7 times, 3.8 times, 3.9 times, 4 times, 4.1 times, 4.2 times, 4.3 times, 4.4 times, 4.5 times, 4.6 times, etc. If the stretching ratio is too small, it may cause insufficient directional arrangement of the iodine complex in the PVA layer, thereby reducing the polarization degree of the polarizer, and the polarization degree is a key indicator for measuring the performance of the polarizer. Too low a polarization degree will reduce the contrast of the display panel; further, the insufficient stretching ratio may also affect the transmittance of the polarizer, resulting in insufficient display brightness, affecting the user experience, and / or making the cross-linking structure of the PVA layer not tight enough, reducing the moisture and heat resistance of the polarizer, and easily failing in high humidity and high temperature environments. If the stretching ratio is too high, it may cause uneven thickness distribution of the PVA layer or even cracks, affecting the product yield; further, although a high stretching ratio can theoretically improve the polarization degree, too high a stretching ratio may also cause excessive internal stress in the PVA layer, which will reduce optical uniformity and even cause rainbow patterns or haze problems.

[0102] Step S30, immersing the PVA layer in a quantum dot solution to obtain a polarizing film, thereby preparing a polarizer, wherein the quantum dots in the quantum dot solution are combined with organic ligands and cross-linked with free hydroxyl groups through the organic ligands.

[0103] In a feasible embodiment, at least one PVA layer containing free hydroxyl groups on its surface is immersed in a quantum dot solution, thereby cross-linking with quantum dots bound to organic ligands in the quantum dot solution to obtain a PVA layer adsorbed with quantum dots as a polarizing film, thereby further preparing a polarizer.

[0104] Optionally, a target solvent that can dissolve quantum dots is determined, quantum dots bound with organic ligands are dissolved in the target solvent to obtain a quantum dot solution, and then the PVA layer is immersed in the quantum dot solution, thereby quickly preparing the polarizing film.

[0105] Optionally, after the stretching step, the PVA layer can be color-corrected using boric acid and / or borax solution, using boric acid to cross-link with the hydroxyl groups of PVA to fix the iodine complex structure, thereby improving moisture and heat resistance and adjusting the color tone of the polarizer (such as neutralizing the blue tone to achieve neutral gray); quantum dots can be combined after color correction.

[0106] Optionally, the quantum dots include: red light quantum dots and / or green light quantum dots.

[0107] Optionally, the quantum dots include: at least one of: II-VI group compounds (e.g., cadmium sulfide, cadmium selenide, cadmium telluride, zinc selenide, etc.), III-V group compounds (e.g., indium phosphide, indium arsenide, etc.), IV-VI group compounds (e.g., lead sulfide, lead selenide, etc.) and perovskite quantum dots (e.g., CsPbI3, etc.).

[0108] In a feasible embodiment, the organic ligand includes at least one of a mercaptocarboxylic acid ligand, an aminosilane ligand, an isocyanate ligand and a phosphate ligand.

[0109] Optionally, the polarizing film may include single-color quantum dots, thereby avoiding the risk of uneven dispersion of multi-color quantum dots, reducing the amount of quantum dots used, and saving raw material costs.

[0110] Optionally, the mercaptocarboxylic acid ligand includes at least one of thioglycolic acid, mercaptopropionic acid, mercaptoalanine and mercaptoundecanoic acid.

[0111] Optionally, the aminosilane ligand includes at least one of 3-aminopropyltrimethoxysilane and 3-glycidyloxysilane.

[0112] Optionally, the isocyanate ligand includes at least one of hexamethylene diisocyanate and isophorone diisocyanate.

[0113] Optionally, the phosphate ligand includes triethyl phosphate and / or methacrylate phosphate.

[0114] Illustratively, the organic ligand includes at least one of thioglycolic acid, mercaptopropionic acid, mercaptoalanine and mercaptoundecanoic acid.

[0115] In one feasible implementation, after the step of obtaining the polarizing film in step S30, the method further includes:

[0116] Step S31, preparing a first supporting layer and a second supporting layer on two layers of the polarizing film respectively;

[0117] Step S32, preparing a first protective layer on a surface of the first supporting layer away from the polarizing film;

[0118] Step S33, preparing a second protective layer on a surface of the second supporting layer away from the polarizing film.

[0119] For example, refer to Figure 7 This is a process flow chart of a conventional polarizer. It can be seen that the preparation process of a conventional polarizer includes: unwinding, swelling, dyeing, washing, stretching (i.e., stretching), color correction, drying, composite TAC film (i.e., the first support layer and / or the second support layer), drying, composite protective film and release film and winding, thereby obtaining a conventional polarizer.

[0120] For example, the present invention provides a method for preparing a polarizer, referring to Figure 8 , the preparation process of the polarizer includes in sequence: unwinding, swelling, dyeing, washing, extension (i.e. stretching), color correction, quantum dot (QD) solution impregnation, drying, composite TAC film (i.e., the first support layer and / or the second support layer), drying, composite protective film and release film and winding, thereby obtaining a polarizer. It can be seen that the embodiment of the present application adds a quantum dot solution impregnation step after the color correction step of the conventional polarizer process flow. After the PVA base film is dyed, the iodine in the dye will penetrate into the PVA crystal to form a PVA-I eutectic. This eutectic structure can be understood as iodine molecules embedded in the gaps formed by the arrangement of PVA molecular chains, so a morphology similar to a "tunnel" is formed; and as the concentration of the iodine solution increases, the hydrogen bonding effect between PVA molecules is weakened, and the destruction of the hydrogen bond network may cause the hydroxyl groups (-OH) originally connected by hydrogen bonds to lose their interaction sites, thereby forming free hydroxyl groups. Furthermore, the molecular chains are oriented by stretching, further destroying the local hydrogen bonds. At the same time, stretching may also expand the defective areas of the PVA crystals, promote iodine penetration, and indirectly aggravate the freeing of hydroxyl groups, and then place the PVA layer in the quantum dot solution; since the quantum dots in the quantum dot solution are combined with organic ligands that can cross-link with free hydroxyl groups, the quantum dots can be combined with the PVA layer through a cross-linking reaction (for example, an esterification reaction of PVA with the ligand thioglycolic acid) to obtain a quantum dot polarizing film. The quantum dot polarizing film is then dried, composited with a TAC film (i.e., the first support layer and / or the second support layer), dried, composited with a protective film and a release film, and rolled up to obtain a polarizer. It can be seen that the overall process is simple and has a high application value.

[0121] In this embodiment, the PVA base film is dyed and stretched so that at least one surface of the obtained PVA layer contains rich free hydroxyl groups, and then the PVA layer is immersed in a quantum dot solution combined with organic ligands, so that the quantum dots are cross-linked with the free hydroxyl groups of the PVA layer through the organic ligands combined with them, thereby realizing the combination of the two to obtain a quantum dot PVA polarizing film, and then a polarizer; the polarizer has both polarizing effect and quantum dot effect; and because the polarizer does not add an additional film layer structure, there is no need to increase the thickness of the polarizer, thereby effectively overcoming the contradiction between the demand for thin and light display devices and the improvement of optical performance, and also avoiding the sudden change of refractive index at the multi-layer interface, reducing the interface light scattering loss, and improving optical uniformity and color purity.

[0122] A third aspect of the embodiments of the present application provides a display module, the display module includes a polarizer, and the polarizer includes a polarizing film;

[0123] Polarizing film includes: PVA layer and quantum dots;

[0124] At least one surface of the PVA layer contains free hydroxyl groups;

[0125] The quantum dots are bound to organic ligands and cross-linked with free hydroxyl groups through the organic ligands.

[0126] Optionally, the polarizer further includes: a first supporting layer, a second supporting layer, a first protective layer and a second protective layer;

[0127] The first supporting layer and the second supporting layer are respectively arranged on both sides of the polarizing film, the first protective layer is arranged on a side of the first supporting layer away from the polarizing film, and the second protective layer is arranged on a side of the second supporting layer away from the polarizing film.

[0128] Optionally, the organic ligand includes at least one of a mercaptocarboxylic acid ligand, an aminosilane ligand, an isocyanate ligand and a phosphate ligand.

[0129] Optionally, the organic ligand includes at least one of thioglycolic acid, mercaptopropionic acid, mercaptoalanine, mercaptoundecanoic acid, 3-aminopropyltrimethoxysilane, 3-glycidyloxysilane, hexamethylene diisocyanate, isophorone diisocyanate, triethyl phosphate and methacrylic acid phosphate.

[0130] Optionally, the PVA layer is a film layer obtained by dyeing and stretching.

[0131] Optionally, the dye used in staining comprises iodine and / or iodide.

[0132] Optionally, the stretching ratio of the PVA layer is 3.7 to 4.6 times.

[0133] Optionally, the content of iodine in the dye is 0.4-1 wt.%.

[0134] Optionally, the content of iodide in the dye is 1 to 1.5 wt.%.

[0135] For example, refer to Fig. 9 The display module includes a back plate 210, a light source 220, a diffuser 230, a first polarizer 240, a liquid crystal glass 250, and a second polarizer 260, which are arranged in sequence. The back plate 210 is a structure that supports the entire display module and provides heat dissipation and electromagnetic shielding functions. The light source 220 can provide a backlight source for the display module. For example, the light source 220 can be an LED lamp bead. The diffuser 230 is used to homogenize the light emitted by the backlight source 220, eliminate the "hot spot" phenomenon (uneven brightness) of the light source 220, ensure uniform distribution of light, and provide a soft surface light source 220 for the upper layer. The first polarizer 240 and the second polarizer 260 are arranged orthogonally to form the basis of the optical switch; optionally, the first polarizer 240 and / or the second polarizer 260 are polarizers as described above (hereinafter referred to as quantum dot polarizers for easy distinction), and the quantum dot polarizer includes a polarizing film, and the polarizing film includes: a PVA layer and quantum dots; at least one surface of the PVA layer contains free hydroxyl groups; the quantum dots are combined with organic ligands and cross-linked with the free hydroxyl groups through the organic ligands. The liquid crystal glass 250 can control the arrangement direction of the liquid crystal molecules through an electric field, change the polarization state of light, and realize the brightness and darkness control of the pixels.

[0136] Optionally, the first polarizer 240 is a quantum dot polarizer, wherein green quantum dots are added to the polarizing film of the quantum dot polarizer, and the second polarizer 260 is a conventional polarizer. It can be further combined with a white light LED (light source 220), that is, the image quality of LCD with high color gamut can be achieved.

[0137] Optionally, both the first polarizer 240 and the second polarizer 260 are quantum dot polarizers, wherein green quantum dots are added to the polarizing film of the first polarizer 240 , and red quantum dots are added to the polarizing film of the second polarizer 260 .

[0138] A fourth aspect of an embodiment of the present application provides a display device, the display device comprising the polarizer as described above.

[0139] The beneficial effects of the display device provided in the embodiment of the present application are the same as the beneficial effects of the polarizer provided in the above embodiment, and other technical features in the display device are the same as the features disclosed in the above embodiment method, which will not be repeated here.

[0140] The above are only preferred embodiments of the present application, and do not limit the scope of the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of patent protection of the present application.

Claims

1. A polarizer, characterized in that: The polarizer includes a polarizing film, and the polarizing film includes a PVA layer and quantum dots; At least one surface of the PVA layer contains free hydroxyl groups; The quantum dots are combined with organic ligands and cross-linked with the free hydroxyl groups through the organic ligands.

2. The polarizer according to claim 1, wherein: The polarizer also includes: a first supporting layer, a second supporting layer, a first protective layer and a second protective layer; The first supporting layer and the second supporting layer are respectively arranged on both sides of the polarizing film, the first protective layer is arranged on a side of the first supporting layer away from the polarizing film, and the second protective layer is arranged on a side of the second supporting layer away from the polarizing film.

3. The polarizer according to claim 1, wherein: The organic ligand comprises at least one of mercaptocarboxylic acid ligands, aminosilane ligands, isocyanate ligands and phosphate ligands.

4. The polarizer according to claim 1, wherein: The organic ligand comprises at least one of mercaptoacetic acid, mercaptopropionic acid, mercaptoalanine, mercaptoundecanoic acid, 3-aminopropyltrimethoxysilane, 3-glycidyloxysilane, hexamethylene diisocyanate, isophorone diisocyanate, triethyl phosphate and methacrylic acid phosphate.

5. The polarizer according to claim 1, wherein: The PVA layer is a film layer obtained by dyeing and stretching.

6. The polarizer according to claim 5, characterized in that: The dye used in the dyeing includes iodine and / or iodide; And / or, the stretching ratio of the PVA layer is 3.7 to 4.6 times.

7. The polarizer according to claim 6, wherein: The content of iodine in the dye is: 0.4-1wt.%; And / or, the content of iodide in the dye is: 1-1.5wt.%.

8. A method for preparing a polarizer, characterized in that: The method for preparing a polarizer is used to prepare a polarizer as claimed in any one of claims 1 to 7, comprising the following steps: Provide PVA base film; Dyeing and stretching the PVA base film to obtain a PVA layer, wherein at least one surface of the PVA layer contains free hydroxyl groups; The PVA layer is immersed in a quantum dot solution to obtain a polarizing film and a polarizing plate, wherein the quantum dots in the quantum dot solution are combined with organic ligands and are cross-linked with the free hydroxyl groups through the organic ligands.

9. A display module, characterized in that: The display module comprises the polarizer according to any one of claims 1 to 7.

10. A display device, characterized in that: The display device comprises the polarizer according to any one of claims 1 to 7.

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