An anti-glare polyvinyl alcohol film, its preparation method and a polarizer

Abstract

The present invention discloses an anti-glare polyvinyl alcohol film, a preparation method thereof and an application thereof, relating to the technical field of polyvinyl alcohol films. The polyvinyl alcohol film comprises the following components in parts by weight: 80-90 parts of PVA resin, 8-10 parts of plasticizer, 0.1-0.5 part of surfactant, 0.5-1 part of antioxidant, 0.5-1 part of ultraviolet absorber, and 0.1-1.5 parts of anti-glare particles; wherein, the anti-glare particles are shell microspheres formed by the combination of hydrophilic nano-particles and hydrophilic organic microspheres; by adding anti-glare functional particles into the polyvinyl alcohol film, the anti-glare function of the polarizer is realized, and meanwhile, the optical properties such as the polarization degree and transmittance of the polyvinyl alcohol film after iodine dyeing and stretching are not affected. Compared with the conventional polarizer that realizes anti-glare by relying on the TAC layer, the prepared polarizer has better optical uniformity of anti-glare, and meanwhile, there is no problem of display optical non-uniformity caused by damage to the TAC anti-glare coating, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of polyvinyl alcohol films, and particularly relates to an anti-glare polyvinyl alcohol film, a preparation method thereof, and a polarizer. Background Art

[0002] A polarizer is an essential optical element in liquid crystal displays (LCDs) and other optoelectronic devices. Its basic structure consists of a polyvinyl alcohol (PVA) film and two layers of triacetyl cellulose (TAC) films on the upper and lower sides. The PVA film plays a core polarization function, while the TAC film mainly plays a role in protection and support. In addition, there are generally multiple layers of coatings on the surface of the TAC film to endow it with diverse functions, such as anti-reflection, anti-glare, etc. The anti-glare film function can further improve the display quality of the screen. Especially in an environment with strong light or direct sunlight, it can effectively reduce glare, improve the display effect and visual comfort, and achieve high performance and competitiveness of the product.

[0003] Glare refers to the visual condition in which the field of view has an inappropriate brightness distribution or extreme brightness contrast in space and time, resulting in visual discomfort or reduced visibility of objects, mainly caused by the reflection of strong light on the surface. The anti-glare film can reduce light reflection. When light irradiates the anti-glare film, the film material changes the propagation path of the light, and the intensity of the reflected light decreases, thereby reducing the intensity of glare.

[0004] Currently, the anti-glare function of polarizers in the market and patents is mainly achieved by the TAC layer, which is prepared by mixing light-scattering particles with an adhesive resin and coating it on the surface of the TAC. However, this method has some disadvantages. For example, the anti-glare coating is usually thin and is easily affected by external physical factors such as scratches and abrasions, which may cause the coating to lose its anti-glare effect and affect the visual quality. In high-temperature and high-humidity environments, the adhesion of the anti-glare coating may be insufficient, and peeling or blistering may easily occur, affecting the uniformity and consistency of the coating, resulting in insufficient optical performance under the viewing angle, color difference, or uneven brightness. At the same time, with the development trend of thinner polarizers, whether it is possible to achieve the anti-glare function without coating to reduce the thickness is the result that polarizer enterprises are currently striving for. On the other hand, with the development of new displays, the TAC layer of polarizers is gradually required to have multiple functions simultaneously, such as anti-fouling performance, antistatic performance, chemical resistance, scratch resistance, anti-glare, anti-reflection, etc. The addition of each function will greatly increase the manufacturing cost of TAC, which is the main obstacle to reducing the cost of polarizers. Summary of the Invention

[0005] The purpose of the present invention is to provide an anti-glare polyvinyl alcohol film, a preparation method thereof, and a polarizer to solve the following technical problems:

[0006] How to achieve the anti-glare function on other layers in a non-coated manner.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] In a first aspect, the present invention discloses an anti-glare polyvinyl alcohol film, which comprises the following components by weight: 80-90 parts of PVA resin, 8-10 parts of plasticizer, 0.1-0.5 part of surfactant, 0.5-1 part of antioxidant, 0.5-1 part of ultraviolet absorber, and 0.1-1.5 parts of anti-glare particles;

[0009] Among them, the anti-glare particles are shell microspheres formed by combining hydrophilic nanoparticles and hydrophilic organic microspheres, and the mass fraction of the hydrophilic nanoparticles in the shell microspheres is 1-10%; the surface of the shell microspheres contains hydrophilic groups such as hydroxyl groups, carboxyl groups, and amino groups, making them have good compatibility and dispersibility in the casting solution.

[0010] Further, the hydrophilic nanoparticles are any one or a combination of silica nanoparticles, titanium dioxide nanoparticles, zirconium dioxide nanoparticles, and alumina nanoparticles, and the nanoparticles are prepared by the sol-gel method.

[0011] Further, the hydrophilic organic microspheres are any one or a combination of polyvinyl alcohol-based microspheres, polymethyl methacrylate-based microspheres, and polystyrene-based microspheres.

[0012] Further, the preparation method of the shell microspheres comprises the following steps:

[0013] Step 1: Prepare hydrophilic nanoparticles with a positively charged surface;

[0014] Add the precursor solution of hydrophilic nanoparticles and a dispersant to a mixed solvent of ethanol and ammonia water, then hydrolyze at the hydrolysis temperature, and finally centrifuge and vacuum dry to obtain hydrophilic nanoparticles with a positively charged surface;

[0015] Taking silica nanoparticles as an example, the preparation process is as follows: Add a certain amount of tetraethyl orthosilicate and vinyltriethoxysilane to a mixed solvent of ammonia water and ethanol, mix them, then hydrolyze at 40 °C for 1 h, stand for aging for 24 h, and finally centrifuge and vacuum dry for 24 h to obtain nano-silica particles with a positively charged surface and a particle size of 10-30 nm;

[0016] Step 2: Prepare hydrophilic organic microspheres with a negatively charged surface;

[0017] Disperse the hydrophilic organic microspheres in a sodium hydroxide solution to partially deprotonate the hydrophilic groups, and then centrifuge and dry to obtain hydrophilic organic microspheres with a negatively charged surface.

[0018] Taking polyvinyl alcohol microspheres as an example, the preparation process is as follows: Soak a certain amount of polyvinyl alcohol microspheres in a 0.1 mol / L sodium hydroxide solution and stir at room temperature for 12 - 24 h. After centrifugation and drying, negatively charged polyvinyl alcohol microspheres are obtained.

[0019] Step 3: Add the positively charged hydrophilic nanoparticles and the negatively charged hydrophilic organic microspheres into an ethanol solvent in proportion, mix for 15 - 20 h, and then centrifuge and dry to obtain the shell microspheres.

[0020] Furthermore, the refractive index difference between the shell microspheres and the PVA resin is 0.01 - 0.1. If the difference is too high, although it will significantly increase the haze of the film, it will also greatly reduce the transmittance of the film. If the difference is small, the effect of improving the haze of the film is relatively weak. And the refractive index difference between the hydrophilic nanoparticles and the hydrophilic organic microspheres in the shell microspheres is 0.01 - 0.1. This difference can make the scattering effect better after multiple refractions and reflections of light, and the Mie scattering that occurs after light passes through the hydrophilic organic microspheres and the Rayleigh scattering that occurs after passing through the hydrophilic nanoparticles can enhance the uniformity and transmittance of light, thereby improving the high-transmittance and high-haze performance of the film.

[0021] Furthermore, the average particle size of the shell microspheres is ≤5 μm to avoid loss due to the particle shell microspheres being blocked by the filter due to too large a particle size.

[0022] When the weight fraction of the PVA resin is 80 - 90 parts, the weight fraction of the anti-glare particles is strictly controlled at 0.1 - 1.5 parts. This is because if the content of the anti-glare particles is too high, it will cause an increase in the haze of the film, and at the same time, it is easy to cause agglomeration of the anti-glare particles, and it will weaken the complexation of the PVA molecular chain and iodine, affecting the optical properties of the anti-glare polyvinyl alcohol film and the polarizer prepared. If the content is too low, the anti-glare effect cannot be effectively produced.

[0023] Furthermore, the degree of polymerization of the PVA resin is 2000 - 4000. This is because if the degree of polymerization is too high, it will lead to uneven dispersion of the additive and poor chromaticity uniformity of the prepared film; if it is too low, the mechanical tensile properties of the optical film will become poor and it is easy to break the film.

[0024] Furthermore, the degree of alcoholysis of the PVA resin is 98 - 99.9%, preferably 99 - 99.9%. This is because if the degree of alcoholysis is too low, the stability of the hydrogen bond network of the prepared PVA polarizer is worse, the film shrinkage under high temperature and high humidity is worse, and in addition, if the degree of alcoholysis is too low, the PVA is easy to absorb water under high temperature and high humidity, and the weather resistance of the polarizer becomes poor.

[0025] Furthermore, the plasticizer is any one or a combination of glycerol, diglycerol, polyglycerol, ethylene glycol, and propylene glycol.

[0026] Further, the surfactant is a composition of at least two surfactants selected from nonionic surfactants and / or anionic surfactants. Among them, the nonionic surfactants include alkyl esters such as polyoxyethylene lauryl ester, alkyl amines such as polyoxyethylene lauryl amino ester, and alkyl amide surfactants such as polyoxyethylene lauric acid amide; the anionic surfactants include alkyl sulfonates, sodium dodecyl sulfate, sodium dodecyl sulfite, benzenesulfonates, and alkyl carboxylates.

[0027] Further, the antioxidant is a composition of any one or more of butylated hydroxytoluene, phosphite, phosphate, thiodipropionate, and sodium bisulfite.

[0028] Further, the ultraviolet absorber is a composition of any one or more of benzotriazoles, benzophenones, triazines, and benzoates.

[0029] In a second aspect, the present invention discloses a method for preparing the anti-glare polyvinyl alcohol film as described above, comprising the following steps:

[0030] S1. Add PVA resin, plasticizer, surfactant, antioxidant, ultraviolet absorber, and anti-glare particles to the solvent in proportion by weight, heat to 130 - 170 °C, and stir for 2 - 10 h, preferably stir at 145 - 160 °C for 4 - 7 h to obtain a casting solution with a solute mass fraction of 20 - 40%.

[0031] S2. Feed the casting solution into an extruder for degassing. The pressure at the head of the extruder is 1.0 - 2.0 MPa, the temperature in the middle section is 100 - 150 °C, and the pressure of the G / P inlet pump is 2.0 - 5.0 MPa; if the pressure is too low, the degassing effect is poor, and if the pressure is too high, the equipment load is too large.

[0032] S3. Filter the degassed casting solution using a disk filter with a filtration pore size of 10 - 20 μm; if the filter pore size is too large, impurities and gels cannot be removed, and if the pore size is too small, the pressure drop is too large, the equipment power load increases, and at the same time, some anti-glare particles will also be filtered.

[0033] S4. Cast the filtered casting solution through a slot die onto a casting roll to form a liquid film. The diameter, linear velocity, temperature, wind field, feed rate of the extruder, and die cross-sectional area of the casting roll should be matched to reduce the water content of the liquid film to 18 - 35%, preferably 22 - 28%. If the water content of the liquid film is controlled too high at this time, it is difficult to peel off, and the load in the subsequent pre-drying stage increases; if the water content of the liquid film is controlled too low, the equipment load is too large and the productivity decreases. Then, pre-dry to reduce the water content to 5 - 15%. If the water content is too low at this time, it is not conducive to forming a uniform and dense PVA crystal network, and the stability of the prepared PVA polarizer crystal and chemical cross-linking network becomes poor, and the mechanical properties become poor; if the water content is too high, it is not conducive to the subsequent heat treatment process, and problems such as water droplets and glycerol are likely to occur. Then, reduce the water content to 0.1 - 5%, preferably 1.5 - 3.5% through heat treatment. If the water content is too low at this time, it is easy to cause difficulties in dyeing during the processing of the polarizer; if it is too high, it will cause a slow change in the crystal structure of PVA during storage, shorten the shelf life, and easily cause an increase in the PVA dissolution amount during production. Finally, wind up to obtain an anti-glare polyvinyl alcohol film.

[0034] Further, in step S4, the heat treatment stage can be selected in a single-stage or multi-stage manner, preferably in a multi-stage manner, and the temperature of each stage shows a trend of first rising and then falling along the production direction.

[0035] Furthermore, the temperature of the highest stage of heat treatment is reduced by 5 - 10 °C, and the linear velocity of the heat treatment guide roll is reduced by 0.5 - 1 m / min to extend the heat treatment time; because heat treatment at a lower temperature can make the film maintain a smaller grain size, and a smaller grain size is beneficial to improving the light transmittance of the film, and longer heat treatment time helps to release residual stress, reduce internal stress, and improve the ductility and toughness of the film.

[0036] Further, the solvent is water or dimethyl sulfoxide.

[0037] Further, the light transmittance of the anti-glare polyvinyl alcohol film is ≥85%, and the haze is 2 - 50%.

[0038] In a third aspect, the present invention also discloses a polarizer. The intermediate film of the polarizer is a polarizing film made by iodine dyeing and stretching of the anti-glare polyvinyl alcohol film as described above. The glossiness of the polarizing film at a 60° angle is 30 - 70 GU, making it have excellent anti-glare performance and not affecting its optical performance.

[0039] The beneficial effects of the present invention:

[0040] (1) In the preparation process of the anti-glare polyvinyl alcohol film of the present invention, anti-glare functional particles are added to the polyvinyl alcohol film to achieve the anti-glare function of the polarizer, while not affecting the optical properties such as the polarization degree and transmittance of the polyvinyl alcohol film after iodine dyeing and stretching. Compared with the polarizer that relies on the TAC layer to achieve anti-glare conventionally, since the anti-glare particles are uniformly dispersed in the PVA optical film, the optical uniformity of the anti-glare of the polarizer is better, and there is no problem of display optical non-uniformity caused by damage to the TAC anti-glare coating. At the same time, the preparation process is saved, the preparation process is simplified, and an anti-glare polyvinyl alcohol film with stronger optical properties is obtained.

[0041] (2) By realizing the anti-glare function in the PVA optical film layer, the present invention can reduce the functions that the TAC layer needs to achieve, reduce the raw material cost and operation cost of the polarizer, and make the product have higher market competitiveness. Description of the Drawings

[0042] The present invention will be further described below with reference to the accompanying drawings.

[0043] Figure 1 is the SEM image of the positively charged nano-silica in Example 1 of the present invention;

[0044] Figure 2 is the SEM image of the negatively charged polyvinyl alcohol microspheres in Example 1 of the present invention;

[0045] Figure 3 is the SEM image of the shell microspheres in Example 1 of the present invention;

[0046] Figure 4 is the SEM image of the anti-glare polyvinyl alcohol film in Example 2 of the present invention;

[0047] Figure 5 is the EDS energy spectrum of the anti-glare polyvinyl alcohol film in Example 2 of the present invention. Detailed Embodiments

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

[0049] The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and are carried out according to the technologies or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0050] Example 1

[0051] Preparation of anti-glare particles:

[0052] Step 1: Mix 100 g of tetraethyl orthosilicate and 10 g of vinyltriethoxysilane with 2500 g of ethanol and 150 g of ammonia water mixed solvent, then hydrolyze at 40 °C for 1 h and stand for aging for 24 h, and finally vacuum dry for 12 - 24 h to obtain positively charged nano-silica. The prepared nano-particles are observed by electron microscopy, and the SEM image as shown in Figure 1 is obtained, and its particle size is 10 - 50 nm;

[0053] Step 2: Disperse 100 g of polyvinyl alcohol microspheres in 0.1 mol / L sodium hydroxide solution, stir at room temperature for 24 h, and then centrifuge and dry to obtain negatively charged polyvinyl alcohol microspheres. The prepared microspheres are observed by electron microscopy, and the SEM image as shown in Figure 2 is obtained, and its particle size ≤ 5 μm;

[0054] Step 3: Add 5 g of positively charged nano-silica and 95 g of negatively charged polyvinyl alcohol microspheres to 300 mL of ethanol solvent, mix for 15 - 20 h, and then centrifuge and dry to obtain shell microspheres. The prepared shell microspheres are observed by electron microscopy, and the SEM image as shown in Figure 3 is obtained, and its particle size ≤ 5 μm, and the dispersion of nano-particles on the surface of the microspheres is good.

[0055] Example 2

[0056] Preparation of anti-glare polyvinyl alcohol film:

[0057] Add 850 g of PVA resin, 90 g of glycerol, 3 g of sodium dodecylbenzenesulfonate, 8 g of butylated hydroxytoluene, 7 g of methyl benzoate, and 10 g of the anti-glare particles prepared in Example 1 to 2259 g of water in sequence, heat to 150 °C and stir for 6 h to obtain a casting solution with a solute mass fraction of 30%; feed the casting solution into an extruder for degassing, the pressure at the extruder head is 1.5 MPa, the temperature in the middle section is 130 °C, and the pressure of the G / P inlet pump is 3.5 MPa; the degassed casting solution is filtered by a disk filter with a filtration pore size of 15 μm; the filtered casting solution is cast onto a casting roll through a slit die to form a liquid film, reduce the water content of the liquid film to 25%, then reduce the water content to 12% by pre-drying, and then reduce the water content to 3% by heat treatment, and finally wind up to obtain an anti-glare polyvinyl alcohol film. The prepared anti-glare polyvinyl alcohol film is sampled and observed by electron microscopy, and the SEM image as shown in Figure 4 and the corresponding EDS energy spectrum diagram as shown in Figure 5 are obtained. It can be found that the anti-glare particles are well dispersed in the PVA matrix and no agglomeration occurs.

[0058] Example 3

[0059] Prepare an anti-glare polyvinyl alcohol film:

[0060] Add 800 g of PVA resin, 80 g of glycerol, 1 g of sodium dodecylbenzenesulfonate, 5 g of butylated hydroxytoluene, 5 g of methyl benzoate, and 1 g of the anti-glare particles prepared in Example 1 into 3568 g of dimethyl sulfoxide solvent in sequence. After heating to 145 °C, stir for 7 h to obtain a casting solution with a solute mass fraction of 20%; feed the casting solution into an extruder for degassing. The pressure at the head of the extruder is 1.0 MPa, the temperature in the middle section is 100 °C, and the pressure of the G / P inlet pump is 2.0 MPa; the degassed casting solution is filtered using a disk filter with a filtration pore size of 10 μm; the filtered casting solution is cast onto a casting roller through a slot die to form a liquid film, reduce the water content of the liquid film to 18%, then reduce the water content to 5% through pre-drying, and further reduce the water content to 1% through heat treatment, and finally wind up to obtain the anti-glare polyvinyl alcohol film.

[0061] Example 4

[0062] Prepare an anti-glare polyvinyl alcohol film:

[0063] Add 900 g of PVA resin, 100 g of glycerol, 5 g of sodium dodecylbenzenesulfonate, 10 g of butylated hydroxytoluene, 10 g of methyl benzoate, and 15 g of the anti-glare particles prepared in Example 1 into 1560 g of dimethyl sulfoxide solvent in sequence. After heating to 160 °C, stir for 4 h to obtain a casting solution with a solute mass fraction of 40%; feed the casting solution into an extruder for degassing. The pressure at the head of the extruder is 2.0 MPa, the temperature in the middle section is 150 °C, and the pressure of the G / P inlet pump is 5.0 MPa; the degassed casting solution is filtered using a disk filter with a filtration pore size of 20 μm; the filtered casting solution is cast onto a casting roller through a slot die to form a liquid film, reduce the water content of the liquid film to 35%, then reduce the water content to 15% through pre-drying, and further reduce the water content to 5% through heat treatment, and finally wind up to obtain the anti-glare polyvinyl alcohol film.

[0064] Example 5

[0065] Prepare an anti-glare polyvinyl alcohol film:

[0066] Add 850 g of PVA resin, 90 g of ethylene glycol, 3 g of potassium laurate, 8 g of phosphite, 7 g of methyl benzoate, and 10 g of the anti-glare particles prepared in Example 1 to 2259 g of water in sequence. After heating to 150 °C, stir for 6 h to obtain a casting dope with a solute mass fraction of 30%. Feed the casting dope into an extruder for degassing. The pressure at the head of the extruder is 1.5 MPa, the temperature in the middle section is 120 °C, and the pressure of the G / P inlet pump is 3.5 MPa. The degassed casting dope is filtered using a disk filter with a filtration pore size of 15 μm. The filtered casting dope is cast onto a casting roll through a slot die to form a liquid film, reduce the water content of the liquid film to 25%, then reduce the water content to 12% through pre-drying, and further reduce the water content to 3% through heat treatment. Finally, wind up to obtain an anti-glare polyvinyl alcohol film.

[0067] Example 6

[0068] Prepare an anti-glare polyvinyl alcohol film:

[0069] Add 850 g of PVA resin, 90 g of diglycerol, 3 g of polyoxyethylene lauryl amino ester, 8 g of thiodipropionate, 7 g of methyl 3,4,5-trimethoxybenzoate, and 10 g of the anti-glare particles prepared in Example 1 to 2259 g of dimethyl sulfoxide solvent in sequence. After heating to 150 °C, stir for 6 h to obtain a casting dope with a solute mass fraction of 30%. Feed the casting dope into an extruder for degassing. The pressure at the head of the extruder is 1.5 MPa, the temperature in the middle section is 130 °C, and the pressure of the G / P inlet pump is 3.5 MPa. The degassed casting dope is filtered using a disk filter with a filtration pore size of 15 μm. The filtered casting dope is cast onto a casting roll through a slot die to form a liquid film, reduce the water content of the liquid film to 25%, then reduce the water content to 12% through pre-drying, and further reduce the water content to 3% through heat treatment. Finally, wind up to obtain an anti-glare polyvinyl alcohol film.

[0070] Comparative Example 1

[0071] Prepare an anti-glare polyvinyl alcohol film:

[0072] 850 g of PVA resin, 90 g of glycerol, 3 g of sodium dodecylbenzenesulfonate, 8 g of butylated hydroxytoluene, and 7 g of methyl benzoate were added to 2259 g of water. After heating to 150 °C and stirring for 6 h, a casting solution was obtained. The casting solution was fed into an extruder for degassing. The pressure at the head of the extruder was 1.5 MPa, the temperature in the middle section was 120 °C, and the pressure of the G / P inlet pump was 3.5 MPa. The degassed casting solution was filtered using a disk filter with a filtration pore size of 15 μm. The filtered casting solution was cast onto a casting roll through a slot die to form a liquid film, and the water content of the liquid film was reduced to 25%. Then, it was pre-dried to reduce the water content to 12%, and further heat-treated to reduce the water content to 3%. Finally, a polyvinyl alcohol film was obtained by winding. Then, on one side of the polyvinyl alcohol film, a commercially available anti-glare coated TAC film was adhered through PVA aqueous glue. The haze of the anti-glare TAC film was the same as that of the anti-glare polyvinyl alcohol film in Example 2.

[0073] Comparative Example 2

[0074] Compared with Comparative Example 1, the only difference was that the adhered TAC film had no anti-glare coating, and the other steps and conditions were exactly the same.

[0075] Comparative Example 3

[0076] Compared with Example 2, the only difference was that the anti-glare particles prepared in Example 1 were not added, and the other steps and conditions were exactly the same. Finally, a polyvinyl alcohol film was obtained.

[0077] Comparative Example 4

[0078] Preparation of anti-glare polyvinyl alcohol film:

[0079] Compared with Example 2, the only difference was that the addition amount of the anti-glare particles prepared in Example 1 was increased from 10 g to 20 g, and the other steps and conditions were exactly the same. Finally, an anti-glare polyvinyl alcohol film was obtained.

[0080] Comparative Example 5

[0081] Compared with Example 2, the only difference was that the addition amount of the anti-glare particles prepared in Example 1 was decreased from 10 g to 0.5 g, and the other steps and conditions were exactly the same. Finally, an anti-glare polyvinyl alcohol film was obtained.

[0082] Comparative Example 6

[0083] Compared with Example 2, the only difference was that the anti-glare particles were replaced with the nano-silica prepared in Example 1, and the other steps and conditions were exactly the same. Finally, an anti-glare polyvinyl alcohol film was obtained.

[0084] Comparative Example 7

[0085] Compared with Example 2, the difference is only that the anti-glare particles are replaced with the polyvinyl alcohol microspheres prepared in Example 1, and the other steps and conditions are exactly the same. Finally, an anti-glare polyvinyl alcohol film is prepared.

[0086] The optical properties of the polyvinyl alcohol films prepared in Examples 2-6 and Comparative Examples 1-7 were detected, and the detection methods are as follows:

[0087] Transmittance: Detected by a haze meter; Cut a polyvinyl alcohol film with a size of 5×5 cm and fix it at the spot injection position. The instrument automatically detects the transmittance of the film, and performs multiple tests and takes the average;

[0088] Haze: Detected by a haze meter; Cut a polyvinyl alcohol film with a size of 5×5 cm and fix it at the spot injection position. The instrument automatically detects the haze of the film, and performs multiple tests and takes the average;

[0089] Gloss at 60° angle: Detected by a gloss meter; First, calibrate the gloss meter, then place the film on a black background, and stick the gloss meter on the film surface to directly test its gloss, and perform multiple tests and take the average;

[0090] Degree of polarization after dyeing: Detected by the polarization mode of a phase difference meter;

[0091] Monomer transmittance: Detected by the polarization mode of a phase difference meter.

[0092] The test results are listed in Table 1 as follows:

[0093] Table 1

[0094]

[0095] For Figure 1 And analyzing the data in Table 1, it can be known that in the anti-glare polyvinyl alcohol films prepared by the preparation method of the present invention in Examples 2-6, the anti-glare particles have good dispersibility, the transmittance ≥ 85%, and the haze is in the range of 2%-50%, and they have stronger optical properties of high transmittance and high haze, and can be applied to the intermediate film (polarizing film) of a polarizer.

[0096] In Comparative Example 1, a TAC film with an anti-glare coating was laminated on one side of polyvinyl alcohol by the existing technology. Although it has anti-glare performance, the surface coating has problems of poor adhesion and scratch resistance, which easily leads to light non-uniformity; In Comparative Example 2, a pure TAC film was laminated on one side of polyvinyl alcohol by the existing technology, and its anti-glare performance is weak;

[0097] In Comparative Example 3, anti-glare particles were not added, so the anti-glare performance was poor. In Comparative Example 4, the addition amount of anti-glare particles was too much, which would affect the dispersion of anti-glare particles in the polyvinyl alcohol film. Although its haze was very high, the light transmittance decreased significantly, the gloss of the corresponding polarizing film would be reduced, and the complexing ability of the polyvinyl alcohol molecular chain and iodine was also reduced, affecting the polarization degree and light transmittance and other optical properties of the polarizing film. In Comparative Example 5, the addition amount of anti-glare particles was too little, and the anti-glare effect was weak;

[0098] In Comparative Example 6, only nano-silica was added as anti-glare particles, and the obtained polyvinyl alcohol film had a lower haze and a higher gloss. In Comparative Example 7, only polyvinyl alcohol microspheres were added as anti-glare particles. Because its refractive index was close to that of the polyvinyl alcohol matrix, the obtained polyvinyl alcohol film had a high light transmittance, but a low haze and a high gloss.

[0099] The above has described a specific embodiment of the present invention in detail, but the described content is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the present invention application should still fall within the scope covered by the patent of the present invention.

Claims

1. A polarizer, characterized in that, The middle film of the polarizer is a polarizing film made by iodine dyeing and stretching of an anti-glare polyvinyl alcohol film, and the gloss at a 60° angle of the polarizing film is 30-70 GU; The anti-glare polyvinyl alcohol film comprises the following components in parts by weight: 80-90 parts of PVA resin, 8-10 parts of plasticizer, 0.1-0.5 part of surfactant, 0.5-1 part of antioxidant, 0.5-1 part of ultraviolet absorber, 0.1-1.5 parts of anti-glare particles; Among them, the anti-glare particles are shell microspheres formed by combining hydrophilic nanoparticles and hydrophilic organic microspheres, and the mass fraction of hydrophilic nanoparticles in the shell microspheres is 1-10%; The preparation method of the shell microspheres comprises the following steps: Step 1: Add the precursor solution of hydrophilic nanoparticles and a dispersant into a mixed solvent of ethanol and ammonia water, then hydrolyze at the hydrolysis temperature, and finally centrifuge and vacuum dry to obtain hydrophilic nanoparticles with a positive charge on the surface; Step 2: Disperse the hydrophilic organic microspheres in a sodium hydroxide solution to partially deprotonate the hydrophilic groups, and then centrifuge and dry to obtain hydrophilic organic microspheres with a negative charge on the surface; Step 3: Add the hydrophilic nanoparticles with a positive charge on the surface and the hydrophilic organic microspheres with a negative charge on the surface into an ethanol solvent in proportion, mix for 15-20 h, and then centrifuge and dry to obtain shell microspheres; The hydrophilic nanoparticles are any one or a combination of silica nanoparticles, titanium dioxide nanoparticles, zirconium dioxide nanoparticles, and alumina nanoparticles, and the nanoparticles are prepared by a sol-gel method; The hydrophilic organic microspheres are any one or a combination of polyvinyl alcohol-based microspheres, polymethyl methacrylate-based microspheres, and polystyrene-based microspheres.

2. The polarizing plate according to claim 1, wherein, The refractive index difference between the shell microspheres and the PVA resin is 0.01-0.1, and the refractive index difference between the hydrophilic nanoparticles and the hydrophilic organic microspheres in the shell microspheres is 0.01-0.

1.

3. The polarizer according to claim 1, wherein, The plasticizer is any one or a combination of glycerol, polyglycerol, ethylene glycol, and propylene glycol.

4. The polarizer according to claim 1, wherein The surfactant is a combination of at least two surfactants in nonionic surfactants and / or anionic surfactants. Among them, the nonionic surfactants include alkyl ester surfactants, alkyl amine surfactants, and alkyl amide surfactants; the anionic surfactants include alkyl sulfonates, sodium dodecyl sulfate, sodium dodecyl sulfite, benzenesulfonates, and alkyl carboxylates.

5. The polarizer according to claim 1, characterized in that, The antioxidant is any one or a combination of butylated hydroxytoluene, phosphite, phosphate, thiodipropionate, and sodium bisulfite.

6. The polarizer according to claim 1, wherein The ultraviolet absorber is any one or a combination of benzotriazoles, benzophenones, triazines, and benzoate esters.

7. A method for preparing an anti-glare polyvinyl alcohol film in a polarizing film according to any one of claims 1-6, characterized in that, Comprises the following steps: S1: Add PVA resin, plasticizer, surfactant, antioxidant, ultraviolet absorber, and anti-glare particles into a solvent in parts by weight ratio, heat up to 130-170 °C, and stir for 2-10 h to obtain a casting solution with a solute mass fraction of 20-40%; S2. Feed the casting solution into an extruder for degassing. The pressure at the head of the extruder is 1.0 - 2.0 MPa, the temperature in the middle section is 100 - 150 °C, and the pressure of the G / P inlet pump is 2.0 - 5.0 MPa; S3. Filter the degassed casting solution using a disk filter with a filtration pore size of 10 - 20 μm; S4. Cast the filtered casting solution through a slot die onto a casting roll to form a liquid film. At the same time, reduce the water content of the liquid film to 18 - 35%, then reduce the water content to 5 - 15% through pre-drying, and further reduce the water content to 0.1 - 5% through heat treatment. Finally, wind up to obtain the anti-glare polyvinyl alcohol film.

8. The preparation method of the anti-glare polyvinyl alcohol film in the polarizing film according to claim 7, characterized in that, In step S1, the solvent is water or dimethyl sulfoxide.

9. The preparation method of the anti-glare polyvinyl alcohol film in the polarizing film according to claim 7, characterized in that, The light transmittance of the anti-glare polyvinyl alcohol film is ≥85%, and the haze is 2 - 50%.

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