Method for improving optical performance of dyed polaroid at low cost

Abstract

According to the method for improving the optical performance of the dye-series polaroid at low cost, the production and manufacturing procedures are not greatly changed, only the azo dye, the anthraquinone dye, the azide dye, the naphthalimide dye, the benzothiadiazole dye or the leek dye are compounded, and the method is used for dyeing dye-series polaroid products; according to the dye-series polaroid, the transmittance in a near-infrared area can be changed, so that the dye-series polaroid product can simultaneously achieve the transmittance of 38-42% and the polarization degree of 99% or above, the manufacturing cost is reduced, the limitation of T-P trade-off of an existing polaroid is broken through, cooperative improvement and dynamic adjustment of the transmittance and the polarization degree of the dye-series polaroid are achieved, and under the condition of being compatible with an existing production line, the dye-series polaroid has the advantages of being high in practicability and wide in application range. And the harsh optical requirements of different high-end electronic display types are met.

Description

Technical Field

[0001] This invention belongs to the field of optical polarizing element technology, and specifically relates to a low-cost method for improving the optical performance of dyed polarizers. Background Technology

[0002] With the continuous development of society, people have increasingly higher requirements for visual products. High-performance polarizers are one of the important materials for achieving high-requirement visual products. Dyed polarizers are made by adsorbing dichroic dyes onto a polyvinyl alcohol (PVA) substrate. Compared with iodine-based polarizers, they have higher high-temperature resistance and damp-heat stability, and are widely used in harsh environments such as automotive displays and CNC equipment. However, their core drawback is that their optical performance (transmittance, polarization degree) is generally lower than that of iodine-based products, and the core contradiction of dyed polarizers lies in the incompatibility between optical performance and cost control.

[0003] Currently, methods for improving the optical performance of dyed polarizers include: optimization of material formulation and substrate (stretching ratio and dye formulation, etc.), stretching process and structural control (multi-segment stretching and temperature control, etc.), and multilayer composites (interference liquid crystal superposition and composite structures, etc.). The market urgently needs a low-cost solution that can simultaneously improve the transmittance (T) and polarization degree (P) of dyed polarizers through process innovation and structural optimization without significantly altering existing production lines or introducing expensive materials, thus overcoming the cost-effectiveness bottleneck.

[0004] Existing products using single azo / anthraquinone dyes to produce dyed polarizers suffer from low transmittance and polarization degree. This is primarily because dyed polarizers have a high transmittance peak in the near-infrared region, resulting in low polarization degree. Furthermore, high-end electronic products have stringent optical performance requirements for dyed polarizers, and this product's limited optical performance control range leads to poor compatibility with these products and low market competitiveness. Additionally, the high cost of synthetically produced azo / anthraquinone dyes further increases the product's production cost. Summary of the Invention

[0005] The purpose of this invention is to provide a low-cost method for improving the optical performance of dyed polarizers, based on existing technologies. It does not significantly alter the manufacturing process, but simply uses azo dyes, anthraquinone dyes, azido dyes, naphthalimide dyes, benzothiadiazole dyes, or leek dyes in combination for dyeing the polarizer. This alters the transmittance in the near-infrared region, enabling the dyed polarizer to simultaneously achieve 38-42% transmittance and over 99% polarization. This reduces manufacturing costs and breaks the limitation of the existing polarizer's "TP (transmittance) versus polarization" relationship, achieving a synergistic improvement and dynamic adjustment of transmittance and polarization in the dyed polarizer. While remaining compatible with existing production lines, it meets the stringent optical requirements of various high-end electronic displays.

[0006] The technical solution of the present invention is as follows: A low-cost method for improving the optical performance of dyed polarizers includes the following steps: (1) The PVA film is swollen at 28-32℃ and stretched during the swelling process, with a stretching ratio of 1.3-1.5 times. (2) The swollen PVA film is washed with water at 29-33℃. During the washing process, the PVA film is stretched by 0.8-1.1 times. (3) The PVA film after washing is dyed at 40-50℃. During the dyeing process, the PVA film is stretched by 2.0-2.5 times. The dyeing solution is made of the following components by weight: 0.01-0.3 parts dye, 0.0001-0.01 parts auxiliary agent and 100-200 parts water. The dye is a composite dye composed of dye A and one or more dyes B. The weight ratio of dye A to dye B is: dye A is an azo dye; dye B is an anthraquinone dye, azido dye, naphthimide dye, benzothiadiazole dye or leek dye; the auxiliary agent is sodium chloride, sodium sulfate or sodium thiosulfate. (4) The dyed PVA film is stretched at 40-50℃, with a stretching ratio of 1.5-2.0 times. During the stretching process, the structure of the PVA film is strengthened by using a boric acid solution, wherein the concentration of boric acid in the boric acid solution is 2.0-3.0%. (5) The extended PVA film is fixed at 30-35℃ for 20-80s. The fixing agent is boric acid solution with a boric acid concentration of 2.0-3.0%. During the fixing process, the PVA film is extended by 0.8-1.3 times. (6) The PVA film after color fixing is dried at 50-70℃, and the dried PVA film is combined with the saponified TAC film to obtain a polarizer.

[0007] In this invention, the PVA film after washing is dyed at 40-50°C. The dyeing solution is prepared from the following components by weight: 0.01-0.3 parts dye, 0.00001-0.001 parts auxiliary agent, and 50-150 parts water. The auxiliary agent is sodium chloride, sodium sulfate, or sodium thiosulfate, preferably sodium chloride.

[0008] In a preferred embodiment, the dyeing solution is made from the following components in parts by weight: 0.1-0.2 parts dye, 0.00002-0.00005 parts sodium chloride, and 90-110 parts water.

[0009] In a more preferred embodiment, the dyeing solution is made from the following components in parts by weight: 0.15 parts dye, 0.00003 parts sodium chloride, and 100 parts water.

[0010] For the purposes of this invention, the dye is a composite dye composed of dye A and one or more dyes B, wherein dye A is an azo dye; and dye B is an anthraquinone dye, azido dye, naphthimide dye, benzothiadiazole dye, or leek dye. The weight ratio of dye A to dye B is 1:0.3-1.8, and may be, but is not limited to, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.85, 1:0.9, 1:1.0, 1:1.3, 1:1.5, or 1:1.8. Preferably, the weight ratio of dye A to dye B is 1:0.5-1.5, and more preferably, the weight ratio of dye A to dye B is 1:0.7-0.9.

[0011] In step (3), dye A is one or more of Direct Peach 12B, Direct Frozen Yellow G or Direct Blue 2B, preferably Direct Peach 12B.

[0012] In step (3), the anthraquinone dye is a hydroxy anthraquinone or a heterocyclic anthraquinone dye, preferably 2-hydroxy anthraquinone and Reactive Brilliant Blue KN-R.

[0013] In step (3), the azide dye is an AF series azide dye, preferably AF514 dye and AF405 dye.

[0014] In step (3), the naphthalene imide dye is an aminonaphthalene imide or an alkoxynaphthalene imide, preferably 4-aminonaphthalene-1,8-dicarboximide and N-methyl-4-methoxy-1,8-naphthalene imide.

[0015] In step (3), the benzothiadiazole dye is a D-π-A-π-D type extended conjugated structure and a linear structure dye containing multiple BTDs, preferably Fluorescent Yellow 3G and Disperse Blue 148.

[0016] In step (3), the chive dye is a complex chive dye, preferably Solvent Yellow 162 and Acid Complex Blue GGN.

[0017] In a preferred embodiment, the dye is a composite dye composed of dye A and two dyes B, wherein the weight ratio of the two dyes B is 1:2-6, which may be, but is not limited to, 1:2, 1:3, 1:4, 1:5 or 1:6. Preferably, the weight ratio of the two dyes B is 1:3-5, and more preferably, the weight ratio of the two dyes B is 1:4.

[0018] In a more preferred embodiment, the two dyes B are 2-hydroxyanthraquinone and Reactive Brilliant Blue KN-R, respectively. In this case, the dye is a composite dye composed of Direct Pink 12B, 2-hydroxyanthraquinone, and Reactive Brilliant Blue KN-R, wherein the weight ratio of Direct Pink 12B, 2-hydroxyanthraquinone, and Reactive Brilliant Blue KN-R is 4-8:1:3-5; more preferably, the weight ratio of Direct Pink 12B, 2-hydroxyanthraquinone, and Reactive Brilliant Blue KN-R is 6:1:4.

[0019] In a more preferred embodiment, the two dyes B are AF514 dye and AF405 dye, respectively. In this case, the dye is a composite dye composed of Direct Peach 12B, AF514 dye and AF405 dye, wherein the weight ratio of Direct Peach 12B, AF514 dye and AF405 dye is 4-8:1:3-5; more preferably, the weight ratio of Direct Peach 12B, AF514 dye and AF405 dye is 6:1:4.

[0020] In a more preferred embodiment, the two dyes B are 4-aminonaphthalene-1,8-dicarboximide and N-methyl-4-methoxy-1,8-naphthalimide, respectively. In this case, the dye is a composite dye composed of Direct Peach 12B, 4-aminonaphthalene-1,8-dicarboximide, and N-methyl-4-methoxy-1,8-naphthalimide, wherein the weight ratio of Direct Peach 12B, 4-aminonaphthalene-1,8-dicarboximide, and 4-alkoxy-N-methyl-1,8-naphthalimide is 4-8:1:3-5; more preferably, the weight ratio of Direct Peach 12B, 4-aminonaphthalene-1,8-dicarboximide, and 4-alkoxy-N-methyl-1,8-naphthalimide is 6:1:4.

[0021] In a more preferred embodiment, the two dyes B are fluorescent yellow 3G and disperse blue 148, respectively. In this case, the dye is a composite dye composed of direct pink 12B, fluorescent yellow 3G and disperse blue 148, wherein the weight ratio of direct pink 12B, fluorescent yellow 3G and disperse blue 148 is 4-8:1:3-5; more preferably, the weight ratio of direct pink 12B, fluorescent yellow 3G and disperse blue 148 is 6:1:4.

[0022] In a more preferred embodiment, the two dyes B are Solvent Yellow 162 and Acid Complex Blue GGN, respectively. In this case, the dye is a composite dye composed of Direct Pink 12B, Solvent Yellow 162 and Acid Complex Blue GGN, wherein the weight ratio of Direct Pink 12B, Solvent Yellow 162 and Acid Complex Blue GGN is 4-8:1:3-5; more preferably, the weight ratio of Direct Pink 12B, Solvent Yellow 162 and Acid Complex Blue GGN is 6:1:4.

[0023] In the fabrication of optical polarizers, swelling and washing soften the PVA film, homogenize its internal structure, and remove plasticizers. Polyvinyl alcohol (PVA) film is a polymer film, and polymer films form crystalline and amorphous regions during the molding process. The crystalline regions are primarily composed of intramolecular hydrogen bonds, resulting in high structural strength and small intermolecular gaps, which hinders the entry of dye molecules. Swelling and washing utilize the entry of water molecules to form intermolecular hydrogen bonds, thus increasing the intermolecular gaps and reducing the film's structural strength, which facilitates the entry of dye molecules.

[0024] In step (1), when the PVA film is swollen, the swelling temperature is 28-32℃, which can be but is not limited to 29℃, 30℃, 31℃ or 32℃. Without affecting the effect of the present invention, the swelling temperature is preferably 29-31℃, and more preferably 30℃.

[0025] In step (1), when the PVA film is swollen, the swelling time is 60-200s, which can be but is not limited to 60s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 180s or 200s.

[0026] In step (1), the PVA film is stretched during the swelling process, and the stretching ratio is 1.3-1.5 times. It can be, but is not limited to, 1.3 times, 1.34 times, 1.38 times, 1.4 times, 1.42 times, 1.45 times or 1.5 times. Without affecting the effect of the present invention, the stretching ratio is preferably 1.35-1.40 times, and more preferably 1.38 times.

[0027] Polyvinyl alcohol (PVA) films have strong water absorption properties, and temperature can affect the Brownian motion of molecules. Therefore, the washing temperature is set to 29℃-33℃, but is not limited to 29℃, 30℃, 31℃, or 32℃. Without affecting the effectiveness of the invention, the washing temperature is preferably 30-32℃. If the washing temperature is too low, the rate at which water molecules enter the PVA film slows down, thus prolonging the softening time of the PVA film. Secondly, the solubility of plasticizers in PVA films in water also increases with increasing temperature. Too low a washing temperature will lead to insufficient dissolution of plasticizers, affecting the entry of dye molecules during subsequent dyeing and resulting in substandard optical properties. If the washing temperature is too high, it accelerates the entry of water molecules into the PVA film, causing excessive softening of the PVA film, reducing tensile strength, and diluting the dye molecules entering during subsequent dyeing, also resulting in substandard optical properties.

[0028] In step (2), when the PVA membrane is washed with water, the washing time is 60-300s, which can be but is not limited to 60s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 180s, 200s, 240s, 260s, 280s or 300s.

[0029] In step (2), the PVA film is stretched during the water washing process. The stretching ratio is 0.8-1.1 times, and can be, but is not limited to, 0.8 times, 0.85 times, 0.9 times, 0.95 times, 1.0 times, 1.01 times, 1.02 times, 1.03 times, 1.04 times, 1.05 times, 1.06 times, 1.07 times, 1.08 times, 1.09 times or 1.1 times. Without affecting the effect of the present invention, the stretching ratio is preferably 0.9-1.03 times, and more preferably 1.01 times.

[0030] In step (3) of this invention, the structure of the PVA film has not yet been strengthened during the dyeing process. If the temperature is too high, the following two adverse situations will occur: First, the PVA film will further swell and soften, causing its structural strength to drop significantly and leading to breakage during subsequent stretching; second, the excessively high temperature will accelerate the Brownian motion of molecules, increasing the coloring rate and ultimately causing the product's transmittance to decrease and fail to meet the requirements. Therefore, in this invention, the dyeing temperature is set to 40℃-50℃, but it can be, but is not limited to, 40℃, 41℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃ or 50℃. Without affecting the effect of this invention, the dyeing temperature is preferably 45-47℃, and more preferably 46℃.

[0031] In step (3) of this invention, the staining time is 110-125s, which can be, but is not limited to, 110s, 113s, 115s, 118s, 120s, 123s or 125s.

[0032] In step (3), the PVA film is stretched during the dyeing process. The stretching ratio is 2.0-2.5 times, which can be but is not limited to 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times or 2.5 times. Without affecting the effect of the present invention, the stretching ratio is 2.1-2.3 times, preferably 2.2 times.

[0033] In this invention, in step (4), the dyed PVA film is stretched at 40-50°C. The stretching temperature is set to 40-50°C, but can be, but is not limited to, 40°C, 41°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C or 50°C. Without affecting the effect of this invention, the stretching temperature is preferably 45-47°C, and preferably 46°C.

[0034] During the extension process, the structure of the PVA film is strengthened, generally using borax solution or boric acid solution. Boric acid solution is preferred for structural strengthening without affecting product performance. Boric acid can complex with the hydroxyl groups in the PVA film, not only strengthening its structural strength but also reducing its hydrophilicity, thus providing waterproofing. However, excessively high boric acid concentrations can significantly reduce the hydrophilicity of the PVA film, affecting subsequent adhesion. Insufficient boric acid concentrations can cause the PVA film to fold and shrink, resulting in appearance defects. Therefore, when using boric acid solution to strengthen the PVA film structure, the concentration of boric acid in the solution is 2.0%-3.0%, but not limited to 2.0%, 2.1%, 2.2%, 2.3%, 2.5%, 2.6%, 2.8%, or 3.0%. Preferably, the concentration of boric acid in the solution is 2.3%-2.6%, more preferably 2.5%, without affecting product performance.

[0035] In step (4), when the PVA film is stretched, the stretching ratio is 1.5-2.0 times, which can be but is not limited to 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.82 times, 1.84 times, 1.9 times, 1.95 times or 2.0 times. Without affecting the effect of the present invention, the stretching ratio is preferably 1.7-1.9 times, and more preferably 1.82 times.

[0036] After dyeing, PVA film needs to be fixed; otherwise, the dye molecules dyed into the PVA film will fall off again, resulting in increased product permeability and failure to meet requirements. For the present invention, therefore, in step (5), the fixing temperature is set to 30℃-35℃, which can be, but is not limited to, 30℃, 31℃, 33℃, 34℃ or 35℃. Without affecting the effect of the present invention, the fixing temperature is preferably 31-33℃, and more preferably 32℃.

[0037] In step (5), the color fixing time is 20-80s, which can be but is not limited to 20s, 30s, 40s, 50s, 60s, 70s or 80s.

[0038] Through extensive experimental exploration, this invention ultimately determined that boric acid solution is the preferred fixing agent for color fixing. The concentration of boric acid in the boric acid solution is 2.0%-3.0%, and can be, but is not limited to, 2.0%, 2.1%, 2.2%, 2.3%, 2.5%, 2.6%, 2.8%, or 3.0%. Preferably, the concentration of boric acid in the boric acid solution is 2.3%-2.6%, and more preferably 2.5%, without affecting the product's performance.

[0039] In step (5), when fixing the color of the PVA film, the elongation ratio is 0.8-1.3 times, which can be but is not limited to 0.8 times, 0.85 times, 0.9 times, 0.95 times, 1.0 times, 1.1 times, 1.2 times or 1.3 times. Without affecting the effect of the present invention, the elongation ratio is preferably 0.9-1.1 times, and more preferably 1.0 times.

[0040] In this invention, in step (6), the PVA film after color fixing is dried at 50-70°C. The drying temperature can be, but is not limited to, 50°C, 55°C, 60°C, 65°C, or 70°C. Preferably, the drying temperature is 55-65°C, and more preferably 60°C, without affecting the effectiveness of this invention. The drying time is 60-120 seconds, but can be, but is not limited to, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, or 120 seconds.

[0041] In step (6), the TAC membrane is saponified with an 8.0% alkaline solution. The alkaline solution is generally a commonly used alkaline solution in the prior art, such as sodium hydroxide solution, potassium hydroxide solution or sodium carbonate solution.

[0042] Further, in step (6), the TAC film is saponified with an 8.0% sodium hydroxide solution at 45°C, and then the dried PVA film is combined with the saponified TAC film so that the TAC film is attached to both sides of the PVA film to form a TAC-PVA-TAC three-layer film structure, thus obtaining a dyed polarizer.

[0043] The present invention aims to improve the transmittance (T) and polarization degree (P) of dyed polarizers without increasing production costs, so as to more quickly meet the needs of the market customer base.

[0044] The advantages of using the technical solution of this invention are as follows: The method for improving the optical performance of dyed polarizers provided by this invention does not significantly change the manufacturing process. It simply uses azo dyes and anthraquinone dyes, azido dyes, naphthalimide dyes, benzothiadiazole dyes, or leek dyes to dye the polarizer products. This can change the transmittance in the near-infrared region, enabling the dyed polarizer products to simultaneously achieve a transmittance of 38-42% and a polarization degree of over 99%. This reduces manufacturing costs and breaks the limitation of the existing polarizer's "TP inverse relationship," achieving a synergistic improvement and dynamic adjustment of the transmittance and polarization degree of the dyed polarizer. Under the condition of compatibility with existing production lines, it meets the stringent optical requirements of different high-end electronic displays. Detailed Implementation

[0045] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims. Example 1

[0046] Before starting the machine, determine the materials to be used: Wanwei polyvinyl alcohol (PVA) film with a thickness of 75μm; Lucky triacetate cellulose ester (TAC) film with a thickness of 80μm; based on the characteristics of the film materials, determine the swelling and washing temperature and time, dyeing temperature and time, dye concentration, fixing temperature and other relevant parameters. The machine can only be started after the parameters meet the start-up requirements.

[0047] A low-cost method for improving the optical performance of dyed polarizers includes the following steps: (1) Place the PVA film in a swelling tank and swell it at 30°C for 120 seconds. During the swelling process, the PVA film is stretched by 1.38 times.

[0048] (2) The swollen PVA film was placed in a water washing tank and washed at 31°C for 110 seconds. During the water washing process, the PVA film was stretched by 1.01 times.

[0049] (3) The washed PVA film was placed in a dyeing tank and dyed at 46°C for 120 seconds. During the dyeing process, the PVA film was stretched by 2.2 times. The dyeing solution was made of the following components by weight: 0.15 parts dye, 0.00003 parts sodium chloride and 100 parts water. The dye was a composite dye composed of Direct Pink 12B, 2-hydroxyanthraquinone and Reactive Brilliant Blue KN-R. The weight ratio of Direct Pink 12B, 2-hydroxyanthraquinone and Reactive Brilliant Blue KN-R was 6:1:4.

[0050] (4) The fixed PVA film is placed in the stretching tank and stretched at 46°C. The stretching ratio is 1.82 times. During the stretching process, boric acid solution is used to strengthen the structure of the PVA film. The concentration of boric acid in the boric acid solution is 2.5%.

[0051] (5) The extended PVA film is placed in a color-fixing tank and fixed at 32°C. During the color-fixing process, the PVA film is extended by 1.0 times. The color-fixing agent is boric acid solution with a boric acid concentration of 2.5% and a color-fixing time of 60s.

[0052] (6) The PVA film after color fixation is dried at 60°C for 90s. At the same time, the TAC film is saponified at 45°C using an 8.0% sodium hydroxide solution. Then, the dried PVA film and the saponified TAC film are combined so that the TAC film adheres to both sides of the PVA film to form a three-layer film structure, thus obtaining a dyed polarizer. Example 2

[0053] Before starting the machine, determine the materials to be used: Wanwei polyvinyl alcohol (PVA) film with a thickness of 75μm; Lucky triacetate cellulose ester (TAC) film with a thickness of 80μm; based on the characteristics of the film materials, determine the swelling and washing temperature and time, dyeing temperature and time, dye concentration, fixing temperature and other relevant parameters. The machine can only be started after the parameters meet the start-up requirements.

[0054] A low-cost method for improving the optical performance of dyed polarizers includes the following steps: (1) Place the PVA film in a swelling tank and swell it at 30°C for 120 seconds. During the swelling process, the PVA film is stretched by 1.38 times.

[0055] (2) The swollen PVA film was placed in a water washing tank and washed at 31°C for 110 seconds. During the water washing process, the PVA film was stretched by 1.01 times.

[0056] (3) The washed PVA film is placed in a dyeing tank and dyed at 46°C for 120 seconds. During the dyeing process, the PVA film is stretched by 2.2 times. The dyeing solution is made of the following components by weight: 0.15 parts dye, 0.00003 parts sodium chloride and 100 parts water. The dye is a composite dye composed of Direct Peach 12B, AF514 dye and AF405 dye. The weight ratio of Direct Peach 12B, AF514 dye and AF405 dye is 6:1:4.

[0057] (4) The fixed PVA film is placed in the stretching tank and stretched at 46°C. The stretching ratio is 1.82 times. During the stretching process, boric acid solution is used to strengthen the structure of the PVA film. The concentration of boric acid in the boric acid solution is 2.5%.

[0058] (5) The extended PVA film is placed in a color-fixing tank and fixed at 32°C. During the color-fixing process, the PVA film is extended by 1.0 times. The color-fixing agent is boric acid solution with a boric acid concentration of 2.5% and a color-fixing time of 60s.

[0059] (6) The PVA film after color fixation is dried at 60°C for 90s. At the same time, the TAC film is saponified at 45°C using an 8.0% sodium hydroxide solution. Then, the dried PVA film and the saponified TAC film are combined so that the TAC film adheres to both sides of the PVA film to form a three-layer film structure, thus obtaining a dyed polarizer. Example 3

[0060] Before starting the machine, determine the materials to be used: Wanwei polyvinyl alcohol (PVA) film with a thickness of 75μm; Lucky triacetate cellulose ester (TAC) film with a thickness of 80μm; based on the characteristics of the film materials, determine the swelling and washing temperature and time, dyeing temperature and time, dye concentration, fixing temperature and other relevant parameters. The machine can only be started after the parameters meet the start-up requirements.

[0061] A low-cost method for improving the optical performance of dyed polarizers includes the following steps: (1) Place the PVA film in a swelling tank and swell it at 30°C for 120 seconds. During the swelling process, the PVA film is stretched by 1.38 times.

[0062] (2) The swollen PVA film was placed in a water washing tank and washed at 31°C for 110 seconds. During the water washing process, the PVA film was stretched by 1.01 times.

[0063] (3) The washed PVA film was placed in a dyeing tank and dyed at 46°C for 120 seconds. During the dyeing process, the PVA film was stretched by 2.2 times. The dyeing solution was made of the following components by weight: 0.15 parts dye, 0.00003 parts sodium chloride and 100 parts water. The dye was a composite dye composed of Direct Peach 12B, 4-aminonaphthalene-1,8-dicarboximide and N-methyl-4-methoxy-1,8-naphthalimide. The weight ratio of Direct Peach 12B, 4-aminonaphthalene-1,8-dicarboximide and N-methyl-4-methoxy-1,8-naphthalimide was 6:1:4.

[0064] (4) The fixed PVA film is placed in the stretching tank and stretched at 46°C. The stretching ratio is 1.82 times. During the stretching process, boric acid solution is used to strengthen the structure of the PVA film. The concentration of boric acid in the boric acid solution is 2.5%.

[0065] (5) The extended PVA film is placed in a color-fixing tank and fixed at 32°C. During the color-fixing process, the PVA film is extended by 1.0 times. The color-fixing agent is boric acid solution with a boric acid concentration of 2.5% and a color-fixing time of 60s.

[0066] (6) The PVA film after color fixation is dried at 60°C for 90s. At the same time, the TAC film is saponified at 45°C using an 8.0% sodium hydroxide solution. Then, the dried PVA film and the saponified TAC film are combined so that the TAC film adheres to both sides of the PVA film to form a three-layer film structure, thus obtaining a dyed polarizer. Example 4

[0067] Before starting the machine, determine the materials to be used: Wanwei polyvinyl alcohol (PVA) film with a thickness of 75μm; Lucky triacetate cellulose ester (TAC) film with a thickness of 80μm; based on the characteristics of the film materials, determine the swelling and washing temperature and time, dyeing temperature and time, dye concentration, fixing temperature and other relevant parameters. The machine can only be started after the parameters meet the start-up requirements.

[0068] A low-cost method for improving the optical performance of dyed polarizers includes the following steps: (1) Place the PVA film in a swelling tank and swell it at 30°C for 120 seconds. During the swelling process, the PVA film is stretched by 1.38 times.

[0069] (2) The swollen PVA film was placed in a water washing tank and washed at 31°C for 110 seconds. During the water washing process, the PVA film was stretched by 1.01 times.

[0070] (3) The washed PVA film was placed in a dyeing tank and dyed at 46°C for 120 seconds. During the dyeing process, the PVA film was stretched by 2.2 times. The dyeing solution was made of the following components by weight: 0.15 parts dye, 0.00003 parts sodium chloride and 100 parts water. The dye was a composite dye composed of Direct Pink 12B, Fluorescent Yellow 3G and Disperse Blue 148. The weight ratio of Direct Pink 12B, Fluorescent Yellow 3G and Disperse Blue 148 was 6:1:4.

[0071] (4) The fixed PVA film is placed in the stretching tank and stretched at 46°C. The stretching ratio is 1.82 times. During the stretching process, boric acid solution is used to strengthen the structure of the PVA film. The concentration of boric acid in the boric acid solution is 2.5%.

[0072] (5) The extended PVA film is placed in a color-fixing tank and fixed at 32°C. During the color-fixing process, the PVA film is extended by 1.0 times. The color-fixing agent is boric acid solution with a boric acid concentration of 2.5% and a color-fixing time of 60s.

[0073] (6) The PVA film after color fixation is dried at 60°C for 90s. At the same time, the TAC film is saponified at 45°C using an 8.0% sodium hydroxide solution. Then, the dried PVA film and the saponified TAC film are combined so that the TAC film adheres to both sides of the PVA film to form a three-layer film structure, thus obtaining a dyed polarizer. Example 5

[0074] Before starting the machine, determine the materials to be used: Wanwei polyvinyl alcohol (PVA) film with a thickness of 75μm; Lucky triacetate cellulose ester (TAC) film with a thickness of 80μm; based on the characteristics of the film materials, determine the swelling and washing temperature and time, dyeing temperature and time, dye concentration, fixing temperature and other relevant parameters. The machine can only be started after the parameters meet the start-up requirements.

[0075] A low-cost method for improving the optical performance of dyed polarizers includes the following steps: (1) Place the PVA film in a swelling tank and swell it at 30°C for 120 seconds. During the swelling process, the PVA film is stretched by 1.38 times.

[0076] (2) The swollen PVA film was placed in a water washing tank and washed at 31°C for 110 seconds. During the water washing process, the PVA film was stretched by 1.01 times.

[0077] (3) The washed PVA film was placed in a dyeing tank and dyed at 46°C for 120 seconds. During the dyeing process, the PVA film was stretched by 2.2 times. The dyeing solution was made of the following components by weight: 0.15 parts dye, 0.00003 parts sodium chloride and 100 parts water. The dye was a composite dye composed of Direct Pink 12B, Solvent Yellow 162 and Acid Complex Blue GGN. The weight ratio of Direct Pink 12B, Solvent Yellow 162 and Acid Complex Blue GGN was 6:1:4.

[0078] (4) The fixed PVA film is placed in the stretching tank and stretched at 46°C. The stretching ratio is 1.82 times. During the stretching process, boric acid solution is used to strengthen the structure of the PVA film. The concentration of boric acid in the boric acid solution is 2.5%.

[0079] (5) The extended PVA film is placed in a color-fixing tank and fixed at 32°C. During the color-fixing process, the PVA film is extended by 1.0 times. The color-fixing agent is boric acid solution with a boric acid concentration of 2.5% and a color-fixing time of 60s.

[0080] (6) The PVA film after color fixation is dried at 60°C for 90s. At the same time, the TAC film is saponified at 45°C using an 8.0% sodium hydroxide solution. Then, the dried PVA film and the saponified TAC film are combined so that the TAC film adheres to both sides of the PVA film to form a three-layer film structure, thus obtaining a dyed polarizer.

[0081] Comparative Example 1 Before starting the machine, determine the materials to be used: Wanwei polyvinyl alcohol (PVA) film with a thickness of 75μm; Lucky triacetate cellulose ester (TAC) film with a thickness of 80μm; based on the characteristics of the film materials, determine the swelling and washing temperature and time, dyeing temperature and time, dye concentration, fixing temperature and other relevant parameters. The machine can only be started after the parameters meet the start-up requirements.

[0082] A low-cost method for improving the optical performance of dyed polarizers includes the following steps: (1) Place the PVA film in a swelling tank and swell it at 30°C for 120 seconds. During the swelling process, the PVA film is stretched by 1.38 times.

[0083] (2) The swollen PVA film was placed in a water washing tank and washed at 31°C for 110 seconds. During the water washing process, the PVA film was stretched by 1.01 times.

[0084] (3) The washed PVA film is placed in a dyeing tank and dyed at 46°C for 120 seconds. During the dyeing process, the PVA film is stretched by 2.2 times. The dyeing solution is made of the following components by weight: 0.15 parts dye, 0.00003 parts sodium chloride and 100 parts water. The dye is a composite dye composed of Direct Peach 12B, Direct Yellow G and Direct Blue 2B, wherein the weight ratio of Direct Peach 12B, Direct Yellow G and Direct Blue 2B is 6:1:4.

[0085] (4) The fixed PVA film is placed in the stretching tank and stretched at 46°C. The stretching ratio is 1.82 times. During the stretching process, boric acid solution is used to strengthen the structure of the PVA film. The concentration of boric acid in the boric acid solution is 2.5%.

[0086] (5) The extended PVA film is placed in a color-fixing tank and fixed at 32°C. During the color-fixing process, the PVA film is extended by 1.0 times. The color-fixing agent is boric acid solution with a boric acid concentration of 2.5% and a color-fixing time of 60s.

[0087] (6) The PVA film after color fixation is dried at 60°C for 90s. At the same time, the TAC film is saponified at 45°C using an 8.0% sodium hydroxide solution. Then, the dried PVA film and the saponified TAC film are combined so that the TAC film adheres to both sides of the PVA film to form a three-layer film structure, thus obtaining a dyed polarizer.

[0088] The transmittance and polarization degree of the dyed polarizers prepared in the examples and comparative examples were tested, and the specific test results are shown in Table 1.

[0089] The transmittance of the optical lens film was measured using a Shimadzu UV2600 ultraviolet spectrophotometer, and the data was processed using ColorAnalysis software. The specific testing method is as follows: The film sample to be tested was cut into 4cm × 6cm samples. During the test, the absorption axis was maintained at a 45° angle to the 0° edge. The parameters of the Shimadzu UV2600 ultraviolet spectrophotometer were set as follows: slit width of 5nm, scanning speed of medium speed, and scanning wavelength of 380nm-780nm. When calculating the degree of polarization (P), the colorimeter standard was: L* value of 90.88, a* value of -15.5, and b* value of 25.4.

[0090] Table 1 Performance of polarizers with different dyeing systems

[0091] As shown in Table 1, by changing the blending of different dyes of the same weight, there are significant differences in the transmittance and polarization degree of the polarizer. Among them, Examples 1 and 2 simultaneously exhibit good transmittance and polarization degree, indicating that by changing the dye blending, without making significant changes to the production process, it is possible to achieve a synergistic improvement and dynamic adjustment of the transmittance and polarization degree of the dye-based polarizer, thereby reducing manufacturing costs and breaking the limitation of the existing polarizer's "TP inverse relationship".

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications may still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions may be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the optical performance of a low-cost dye-doped polarizer, comprising: The method comprises the following steps: (1) swelling the PVA film at 28-32℃, and stretching the PVA film at a ratio of 1.3-1.5 times during the swelling; (2) washing the swollen PVA film at 29-33℃, and stretching the PVA film at a ratio of 0.8-1.1 times during the washing; (3) dyeing the washed PVA film at 40-50℃, and stretching the PVA film at a ratio of 2.0-2.5 times during the dyeing; wherein the dyeing solution is prepared from the following components by weight: 0.01-0.3 parts of dye, 0.00001-0.001 parts of auxiliary agent, and 50-150 parts of water, the dye is a composite dye composed of dye A and one or more dyes B, the dye A is an azo dye; the dye B is an anthraquinone dye, an azide dye, a naphthalimide dye, a benzothiadiazole dye, or a thiazine dye; the auxiliary agent is sodium chloride, sodium sulfate, or sodium thiosulfate; (4) stretching the dyed PVA film at 40-50℃ at a ratio of 1.5-2.0 times, and strengthening the structure of the PVA film by using a boric acid solution during the stretching, the concentration of boric acid in the boric acid solution being 2.0-3.0%; (5) fixing the color of the stretched PVA film at 30-35℃ for 20-80s by using a boric acid solution as the fixing agent, the concentration of boric acid in the boric acid solution being 2.0-3.0%; and stretching the PVA film at a ratio of 0.8-1.3 times during the fixing; (6) drying the PVA film after the color fixing treatment at 50-70℃, and compounding the dried PVA film with a saponified TAC film to obtain a dyed polarizing sheet.

2. The method of improving the optical performance of a low cost, pulled-dyed polarizer according to claim 1, wherein, In step (3), the auxiliary agent is sodium chloride, the dyeing solution is prepared from the following components by weight: 0.1-0.2 parts of dye, 0.00002-0.00005 parts of sodium chloride, and 90-110 parts of water; preferably, the dyeing solution is prepared from the following components by weight: 0.15 parts of dye, 0.00003 parts of sodium chloride, and 100 parts of water; the weight ratio of dye A to dye B is 1:0.3-1.8, preferably 1:0.5-1.5, and more preferably 1:0.7-0.

9.

3. The method of improving the optical performance of a low cost, pulled-dyed polarizer according to claim 2, wherein, In step (3), the dye A is one or more of Direct Pink 12B, Direct Yellow G, or Direct Blue 2B, preferably Direct Pink 12B; the anthraquinone dye is a hydroxyl anthraquinone and a heterocyclic anthraquinone dye, preferably 2-hydroxyanthraquinone and reactive brilliant blue KN-R; the azide dye is an AF series azide dye, preferably AF514 dye and AF405 dye; the naphthalimide dye is an amino naphthalimide and an alkoxy naphthalimide dye, preferably 4-amino naphthalene-1,8-dicarboximide and N-methyl-4-methoxy-1,8-naphthalimide; The benzothiadiazole dyes are D-π-A-π-D type extended conjugated structure and linear structure dyes containing multiple BTDs, preferably fluorescent yellow 3G and disperse blue 148; The leek dyes are complex leek dyes, preferably solvent yellow 162 and acid complex blue GGN.

4. The method of improving the optical performance of a low cost, pulled-dyed polarizer according to claim 3, wherein The dyes are composite dyes composed of dye A and two dyes B, wherein the weight ratio of the two dyes B is 1:2-6, preferably 1:3-5; more preferably 1:

4.

5. The method of improving the optical performance of a low cost enhanced dye polarizer according to claim 4, wherein, The two dyes B are 2-hydroxyanthraquinone and reactive brilliant blue KN-R or 2-hydroxyanthraquinone and reactive brilliant blue KN-R or AF514 dye and AF405 dye or 4-amino naphthalene-1,8-dicarboximide and N-methyl-4-methoxy-1,8-naphthalimide or fluorescent yellow 3G and disperse blue 148 or solvent yellow 162 and acid complex blue GGN.

6. The method of improving the optical performance of a low cost enhanced dye polarizer according to claim 5, wherein, The dyes are composite dyes composed of direct pink 12B, 2-hydroxyanthraquinone and reactive brilliant blue KN-R, wherein the weight ratio of direct pink 12B, 2-hydroxyanthraquinone and reactive brilliant blue KN-R is 4-8:1:3-5; preferably 6:1:

4.

7. The method for improving the optical performance of a low-cost pull-up dye system polarizing plate according to claim 5, wherein, The dyes are composite dyes composed of direct pink 12B, AF514 dye and AF405 dye, wherein the weight ratio of direct pink 12B, 2AF514 dye and AF405 dye is 4-8:1:3-5; preferably 6:1:4; The dyes are composite dyes composed of direct pink 12B, 4-amino naphthalene-1,8-dicarboximide and N-methyl-4-methoxy-1,8-naphthalimide, wherein the weight ratio of direct pink 12B, 4-amino naphthalene-1,8-dicarboximide and 4-alkoxy-N-methyl-1,8-naphthalimide is 4-8:1:3-5; preferably 6:1:

4.

8. The method for improving the optical performance of a low-cost pull-up dye system polarizing plate according to claim 5, wherein, The dyes are composite dyes composed of direct pink 12B, fluorescent yellow 3G and disperse blue 148, wherein the weight ratio of direct pink 12B, fluorescent yellow 3G and disperse blue 148 is 4-8:1:3-5; preferably 6:1:4; The dyes are composite dyes composed of direct pink 12B, solvent yellow 162 and acid complex blue GGN, wherein the weight ratio of direct pink 12B, solvent yellow 162 and acid complex blue GGN is 4-8:1:3-5; preferably 6:1:

4.

9. The method of improving the optical performance of a low cost, pulled-dyed polarizer according to claim 1, wherein, In step (1), the swelling temperature is 29-31℃, preferably 30℃; the swelling time is 60-200s; the elongation ratio is 1.35-1.40, preferably 1.38; in step (2), the washing temperature is 30-32℃, preferably 31℃; the washing time is 60-300s; the elongation ratio is 0.9-1.03, preferably 1.01; in step (3), the dyeing temperature is 45-47℃, preferably 46℃; the dyeing time is 110-125s; the elongation ratio is 2.1-2.3, preferably 2.

2.

10. The method of improving the optical performance of a low cost, pulled-dyed polarizer according to claim 1, wherein, In step (4), the elongation temperature is 45-47℃, preferably 46℃; the elongation ratio is 1.7-1.9, preferably 1.82; the concentration of boric acid in the boric acid solution is 2.4%-2.6%, preferably 2.5%; in step (5), the fixing temperature is 31-33℃, preferably 32℃; the elongation ratio is 0.9-1.1, preferably 1.0; the concentration of boric acid in the boric acid solution is 2.4%-2.6%, preferably 2.5%; in step (6), the drying temperature is 55-65℃, preferably 60℃; the drying time is 60-120s.

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