Method for manufacturing a polarizing plate having high durability

Abstract

The application discloses a kind of production methods of high durability polarizing sheet, belong to polarizing sheet technical field.The application adds transition high valence metal cation additive in the process of making polarizing sheet, utilizes the characteristics of its hydrolytic polymerization and the polar bond and coordination bond formed by the hydroxyl of PVA using multi-core hydroxyl bridge complex ion, strengthen the crosslinking strength of PVA.High valence metal ion has high coordination ability, high temperature stability is good, can promote the generation and stability of linear polyiodide, so that the polarizing film with excellent durability can be prepared, especially the polarizing film with excellent thermal stability.Effectively solve the phenomenon of polarization degree decline, crack and red light leakage caused by boronic acid reduction or linear I5 ‑ Unstable at high temperature.

Description

Technical Field

[0001] This invention belongs to the field of polarizer technology, specifically relating to a method for manufacturing a high-durability polarizer. Background Technology

[0002] Image display devices using polarizers are widely used in various scenarios such as home, office, industry, and outdoor applications. This widespread use has led to an increase in the need for long-term use under harsh conditions such as high temperature and high humidity. Therefore, polarizers with excellent durability are required to ensure they can still perform their original functions under these harsh conditions.

[0003] For iodine-based polarizing films made of PVA (polyvinyl alcohol) resins, the hydrophilic nature and high hygroscopicity of PVA make the polarizing film sensitive to changes in temperature and humidity. It is prone to expansion and contraction due to environmental changes, leading to cracking. In high-temperature and high-humidity environments, PVA molecular chains relax, causing a decrease in the polarization degree of the polarizer. Furthermore, interconversion of polyiodide ions within the polarizing film occurs, preventing stable absorption at all wavelengths. There is a coupling relationship between molecular chain relaxation and polyiodide ion conversion. The formation and stability of one-dimensional rod-shaped polyiodide ions depend on the high orientation of the molecular chains; deterioration of molecular chain orientation leads to polyiodide ion conversion. Conversely, polyiodide ions play a cross-linking role in the polarizer; their loss also compromises the stability of the molecular chain orientation.

[0004] Boric acid, used as a PVA crosslinking agent in polarizers, decreases under high temperature and humidity conditions, leading to insufficient PVA crosslinking and a decrease in polarization. The linear I3 formed by potassium iodide and iodine molecules in the polarizer... - Ions and I5 - The ions are dichroic substances, exhibiting properties in both the blue and red light regions. Linear I3... - Ions and I5 - Ions complex with polyvinyl alcohol containing multiple hydroxyl groups to form a polyvinyl alcohol-iodine complex, which, after stretching and orientation, exhibits polarization absorption of visible light across the entire wavelength range. Different cations will result in I5... - Ions have different configurations, exhibiting linear or "V" shapes, and simultaneously, I5 in the crystal lattice - Ions may form larger, nonlinear, high-polyiodine chains or surfaces. "V"-shaped I5 - The presence of ions and nonlinear high-polyiodine chains negatively impacts the high polarization degree of polarizers. Furthermore, unlike I3... - Ions can exist stably and independently, I5 - Ions require specific molecular spaces to form. At high temperatures, iodine sublimates, forming I5. - It can easily decompose into I3 - I5 -Same as I - The reaction will also cause I5 - Reduced. Polarizing film due to I5 - The loss of light reduces the absorption of red light, causing the polarizing film to appear reddish. Generally, the stability of polyiodide ions is mainly related to the size, charge, and symmetry of the cation; larger cations can obtain stable polyiodide ions.

[0005] Raman spectroscopy can be used for semi-quantitative determination of the type and relative content of polyiodide ions. (The text then abruptly shifts to a seemingly unrelated topic: PVA after iodine staining, I3...) - The characteristic ion peak appears at 110 cm⁻¹ -1 Nearby, is I3 - Stretching vibration peak. I5 - The characteristic ion peak appears at 158 ​​cm⁻¹ -1 Nearby, belonging to I5 - Bending vibration. Linearity I5 - At 152cm -1 162cm -1 Two characteristic peaks of moderate intensity are present nearby. Furthermore, at 158 ​​cm⁻¹... -1 and 162cm -1 There may also be a "V"-shaped I5 in between. - Vibration peaks. Therefore, Raman spectroscopy can be used to determine the existing form and relative content of polyiodide ions in polarizing films, providing a basis for understanding the impact of process adjustments on polyiodide ions in polarizing films.

[0006] Therefore, to obtain polarizers with excellent performance and high high-temperature durability, it is necessary to avoid insufficient PVA crosslinking caused by boric acid loss under high-temperature conditions, and at the same time, it is necessary to generate and stabilize the linear I5 in the polarizer film. - Ions are prevented from converting into more polymerized iodine or being lost at high temperatures, in order to maintain the polarization degree and high color reproduction of the polarizer in harsh environments. Summary of the Invention

[0007] The purpose of this invention is to provide a method for manufacturing a high-durability polarizer, in order to solve the problems in the prior art where the polarization degree of the polarizer decreases, cracks appear, and red light leaks due to the poor thermal stability of the PVA optical film used in the polarizer.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A method for manufacturing a high-durability polarizing film includes the following steps:

[0010] The polyvinyl alcohol (PVA) optical film undergoes swelling, dyeing, crosslinking, stretching, and color correction processes; wherein a high-valence metal cation additive is added in one or more of the swelling, dyeing, crosslinking, stretching, and color correction processes.

[0011] The optical film is then post-processed to obtain a polarizer.

[0012] Furthermore, the process solutions required for the swelling, dyeing, cross-linking, stretching, and color-correcting processes are swelling solution, dyeing solution, cross-linking solution, stretching solution, and color-correcting solution, respectively.

[0013] Among them, one or more of the following solutions—swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution—contain high-valence metal cation additives.

[0014] Furthermore, the transition high-valent metal cation additive is a soluble Zr(Ⅳ) (tetravalent Zr ion compound), Fe(III) (trivalent Fe ion compound), Cr(Ⅲ) (trivalent Cr ion compound), or Ti(Ⅳ) (tetravalent Ti ion compound);

[0015] Zr(Ⅳ) includes ZrOCl2; Fe(III) includes FeCl3 and Fe2(SO4)3; Ti(Ⅳ) includes TiCl4; Cr(Ⅲ) includes CrI3, Cr2(SO4)3 and CrCl3.

[0016] High-valence metal ions can generate polynuclear bridged ions through hydrolysis and polymerization. These polynuclear hydroxy bridged ions form polar and coordinate bonds with the hydroxyl groups of PVA. In aqueous solution, these polynuclear hydroxy bridged ions form dynamic crosslinks with PVA, offering no obstruction to the stretching and orientation of PVA molecules, thus improving stretching efficiency. After drying, high-valence metal cations form polar bonds and coordination interactions with PVA, boric acid, and polyiodide ions, strengthening the crosslinking between PVA, boric acid, and polyiodide ions. - Ions can exist stably and independently, I5 - Ions require specific molecular spaces to form and stabilize. Under harsh conditions, I5... - It can easily decompose into I3 - I5 - Same as I - The reaction will also cause I5 - Reduced. Meanwhile, the cross-linking of metal cations and PVA forms a spatial supply for linear I5. - The formation and stable existence of steric hindrance prevent the formation of other nonlinear high-iodine polymers (I7). - I 11 - (etc.). Transition metals have many empty orbitals and iodine has many lone pairs of electrons, which can form stable complexes between them, while the high-temperature stability of metal ions ensures the stability of I5. - It does not easily decompose at high temperatures.

[0017] Furthermore, in the transition high-valence metal cation additive, Fe(III) is specifically added to a KI-free swelling solution or crosslinking solution. The solution containing the transition high-valence metal cation additive should not contain substances that could reduce its valence state, produce precipitates, or complex with it to prevent it from forming chemical bonds or complexing with PVA-boric acid-polyiodide ions, thus avoiding a decrease in its effective concentration.

[0018] Furthermore, the concentration of transition high-valence metal ions in the solution containing the transition high-valence metal cation additive is 0.05–0.5 mol / L; preferably, the concentration is 0.1–0.3 mol / L; and even more preferably, the concentration is 0.2–0.25 mol / L. When the additive content is less than 0.05 mol / L, there is only a minor improvement in durability; when the additive content is greater than 0.5 mol / L, the additive residue on the surface after drying will cause external defects.

[0019] Furthermore, the pH of the solution containing the high-valence metal cation additive is 2–3. The purpose of adjusting the pH is to stabilize the added metal ions and inhibit the hydrolysis of metal ions in water to form hydroxide precipitates, which would reduce the effective metal ion concentration in the solution and thus decrease the durability of the polarizing film. Too low a pH may cause equipment corrosion and reduce operability.

[0020] Furthermore, the pH of the solution containing the high-valence metal cation additive is adjusted using an inorganic acid with pK < 3; the inorganic acid includes sulfuric acid, hydrochloric acid, or hydroiodic acid.

[0021] Furthermore, the solutions used in the processing of polyvinyl alcohol optical films contain KI, such as dyeing solutions, stretching solutions, and color-correcting solutions, with the KI mass percentage being 1% to 2%. This ensures sufficient KI to guarantee the polarizer's function while avoiding excessive KI that could cause I5. - Instability decomposition.

[0022] Specifically, a method for manufacturing a high-durability polarizing film includes the following steps:

[0023] (1) Selection of polyvinyl alcohol optical film

[0024] It should be noted that there are no particular limitations on the optical and mechanical properties of the polyvinyl alcohol optical film used in this invention, as long as it meets industry standards. The thickness of the polyvinyl alcohol optical film can be selected from approximately 10 to 100 μm. Polyvinyl alcohol or its derivatives can be used as the materials constituting the polyvinyl alcohol optical film. The degree of polymerization of polyvinyl alcohol is preferably around 2000 to 4000, more preferably 1200 to 3000. The polyvinyl alcohol optical film may also contain additives such as plasticizers and surfactants.

[0025] (2) Swelling

[0026] Before dyeing, the unstretched polyvinyl alcohol (PVA) optical film is immersed in a swelling aqueous solution to remove impurities such as dust and anti-blocking agents from the surface of the PVA optical film. This causes the PVA film to swell. This improves stretching efficiency, prevents uneven dyeing, and enhances the physical properties of the polarizer. Well-known swelling aqueous solutions in the art can be used without particular limitation; for example, water can be used alone, or a small amount of small molecule alcohols such as glycerol can be added. In this invention, if Fe(III) is used as the added high-valence transition metal cation, iodides should not be added to the swelling solution. The temperature of the swelling bath aqueous solution can be 20–40°C, and the residence time can be 40–120 s.

[0027] (3) Staining

[0028] The swollen optical film is stained with iodine solution, causing polyiodide ions to be distributed in a complex manner on the disordered PVA molecular chains. After stretching and orientation, the polyvinyl alcohol-iodine complex exhibits polarization absorption of visible light across the entire wavelength range. The mass percentage of iodine in the staining solution is 0.01%–0.05%, the mass percentage of KI is less than 2%, and the mass percentage of boric acid in the staining solution is less than or equal to 2%. The temperature of the staining solution is 25–38℃, and the iodine staining time is 100–300 s.

[0029] (4) Crosslinking

[0030] The dyed polyvinyl alcohol membrane is immersed in a crosslinking solution, which allows the adsorbed iodine molecules to be fixed on the PVA molecular chain. The mass percentage of boric acid is 3% to 5%, the crosslinking temperature is 25 to 38°C, and the crosslinking time is 20 to 60 seconds.

[0031] (5) Stretching

[0032] The PVA optical film is stretched. During the stretching process, the PVA molecular chains form an ordered molecular structure along the stretching direction, causing only light waves parallel to the molecular chain direction to pass through the polarizer, thus achieving light polarization. The stretching solution contains 1.5%–1.9% potassium iodide and 3%–4% boric acid by mass. The stretching temperature is 55–68°C, and the stretching time is 60–120 seconds. It should be noted that the stretching step can be performed at least once or multiple times. In the case of multiple stretching steps, it can be performed separately in any step of the polarizer manufacturing process. A total stretching ratio of 5–7 times yields optical films with better optical performance.

[0033] (6) Complementary colors

[0034] After stretching, the polarizing film undergoes color correction in a KI and boric acid solution. This process stabilizes the iodine complexes between PVA molecules and can also correct the color of polyvinyl alcohol films that have not been adequately dyed by the iodine complexes in the crosslinking step. In the color correction solution, potassium iodide accounts for 0.8%–1.5% by mass, and boric acid accounts for less than or equal to 2% by mass. The color correction temperature is 20–30°C, and the color correction time is 20–50 seconds.

[0035] (7) Post-processing

[0036] After color correction, the polarizing film undergoes well-known industry processes such as drying, applying a protective film, drying the adhesive, and heat treatment to obtain a polarizing film.

[0037] It should be noted that this invention does not require all of the above steps to be included, nor does it require production to be carried out in the order described above. Adjustments can be made according to actual production needs.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] This invention utilizes a transitional high-valence metal cation additive during the polarizer fabrication process. The hydrolysis and polymerization of this additive generates polynuclear hydroxy-bridged complexes that form polar and coordinate bonds with the hydroxyl groups of PVA, thereby strengthening the crosslinking strength of PVA. Simultaneously, the high coordination ability and good high-temperature stability of the high-valence metal ions promote the formation and stabilization of linear polyiodide ions, thus enabling the production of polarizers with excellent durability, particularly those exhibiting excellent thermal stability. This effectively solves the problem of reduced boric acid content or linear I5 at high temperatures. - Instability causes a decrease in polarization, cracks, and leakage of red light. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] A method for manufacturing a high-durability polarizer, using CrCl3 as a transition high-valence metal cation additive, includes the following steps:

[0043] S1. A 60 μm thick polyvinyl alcohol optical film is immersed in a swelling solution containing CrCl3 for swelling treatment: the swelling solution is deionized water, the pH value of the swelling solution is adjusted to 2.5 using hydrochloric acid, the molar concentration of CrCl3 in the swelling solution is 0.25 mol / L, the temperature of the swelling solution is 30℃, and the swelling time is 100 s.

[0044] S2. The swollen optical film was immersed in a staining solution containing CrCl3 for staining treatment: the mass percentage of I2 in the staining solution was 0.05%, the mass percentage of KI was 1.5%, and the mass percentage of H3BO3 was 1%; the pH value of the staining solution was adjusted to 2.5 using hydrochloric acid, the molar concentration of CrCl3 in the staining solution was 0.25 mol / L, the temperature of the staining solution was 32℃, and the staining time was 140 s;

[0045] S3. The dyed optical film is immersed in a crosslinking solution containing CrCl3 for crosslinking treatment: the mass percentage of H3BO3 in the crosslinking solution is 4%; the pH value of the crosslinking solution is adjusted to 2.5 using hydrochloric acid, the molar concentration of CrCl3 in the crosslinking solution is 0.25 mol / L, the temperature of the crosslinking solution is 30℃, and the crosslinking time is 40s.

[0046] S4. The cross-linked optical film is immersed in a stretching solution containing CrCl3 for stretching treatment: the mass percentage of KI in the stretching solution is 1.6%, and the mass percentage of H3BO3 is 3.5%; the pH value of the stretching solution is adjusted to 2.5 using hydrochloric acid, the molar concentration of CrCl3 in the stretching solution is 0.25 mol / L, the temperature of the stretching solution is 55℃, the stretching time is 100s, and the total stretching ratio is 5.5 times.

[0047] S5. The stretched optical film is immersed in a color-correcting solution containing CrCl3 to obtain a polarizing film: the mass percentage of KI in the color-correcting solution is 1.2%, the mass percentage of H3BO3 is 1.5%, the molar concentration of CrCl3 in the color-correcting solution is 0.25 mol / L; the temperature of the color-correcting solution is 25℃, and the color-correcting time is 25s.

[0048] S6. After color correction, the polarizing film undergoes post-processing production processes known in the industry, such as drying, bonding a protective film, drying the adhesive, and heat treatment, to obtain a polarizing film.

[0049] Example 2

[0050] A method for manufacturing a high-durability polarizing film differs from Example 1 in that the dyeing solution, crosslinking solution, stretching solution, and color-correcting solution do not contain CrCl3, and hydrochloric acid is not used to adjust the pH value, while the remaining steps and parameters remain the same.

[0051] Example 3

[0052] A method for manufacturing a high-durability polarizing film differs from Example 1 in that CrCl3 in the swelling solution and crosslinking solution is replaced with FeCl3, CrCl3 is not added to the dyeing solution, stretching solution and color-correcting solution, and hydrochloric acid is not used to adjust the pH value, while the remaining steps and parameters remain the same.

[0053] Example 4

[0054] A method for manufacturing a high-durability polarizing film differs from Example 1 in that the concentration of CrCl3 in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with 0.05 mol / L, while the remaining steps and parameters remain the same.

[0055] Example 5

[0056] A method for manufacturing a high-durability polarizing film differs from Example 1 in that the concentration of CrCl3 in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with 0.5 mol / L, while the remaining steps and parameters remain the same.

[0057] Example 6

[0058] A method for manufacturing a high-durability polarizing film differs from Example 1 in that the pH value adjusted by hydrochloric acid in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with 2, while the remaining steps and parameters remain the same.

[0059] Example 7

[0060] A method for manufacturing a high-durability polarizing film differs from Example 1 in that the pH value adjusted by hydrochloric acid in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with 3, while the remaining steps and parameters remain the same.

[0061] Example 8

[0062] A method for manufacturing a high-durability polarizing film differs from Example 1 in that CrCl3 in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with ZrOCl2, while the remaining steps and parameters remain the same.

[0063] Example 9

[0064] A method for manufacturing a high-durability polarizing film differs from Example 1 in that CrCl3 in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with TiCl4, while the remaining steps and parameters remain the same.

[0065] Comparative Example 1

[0066] A method for manufacturing a polarizer differs from Example 1 in that the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution do not contain the high-valence metal cation additive CrCl3, and hydrochloric acid is not used to adjust the pH, while the remaining steps and parameters remain the same.

[0067] Comparative Example 2

[0068] A method for manufacturing a polarizer differs from Example 1 in that the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution do not contain the high-valence metal cation additive CrCl3, while the remaining steps and parameters remain the same.

[0069] Comparative Example 3

[0070] A method for manufacturing a polarizer differs from Example 1 in that the concentration of CrCl3 in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with 0.7 mol / L, while the remaining steps and parameters remain the same.

[0071] Comparative Example 4

[0072] A method for manufacturing a polarizer differs from Example 1 in that the pH value adjusted by hydrochloric acid in the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution is replaced with 5, while the remaining steps and parameters remain the same.

[0073] The relevant parameters in Examples 1-9 and Comparative Examples 1-4 are shown in Table 1:

[0074] Table 1

[0075]

[0076]

[0077]

[0078] The performance of the polarizers prepared in Examples 1-9 and Comparative Examples 1-4 was tested:

[0079] 1. The number of point defects in the polarizer is detected online using an automated optical inspection (AOI) device.

[0080] 2. The polarizer was subjected to high-temperature treatment at 105℃ for 500 hours and at 65℃ / 95% humidity for 500 hours respectively. The Raman peaks were identified using the rapid confocal 3D imaging technology of a confocal micro-laser Raman spectrometer (Alpha 300-R type Raman spectrometer), and the I5 peaks were analyzed. -Characteristic peaks were integrated, and the relative content was expressed as the integrated intensity. Measurements were taken at 20 points, and the average value was reported. The polarization degree of the polarizer and the cross-transmittance at 700 nm (red light) were measured using a spectrophotometer (JASCO V-7100, Japan) in the range of 380 nm to 780 nm. Ten measurements were taken for each sample, and the average value was reported.

[0081] Sample quality assessment:

[0082] (1) The number of point defects is less than 50 per 100m 2 A rating of "good" is marked with ○, and the number of defects exceeds 50 per 100m. 2 The evaluation is poor and is marked with ×.

[0083] (2) Using the original polarizer of Example 1, I5 - The strength is recorded as 100, and the remaining samples are I5. - The intensity report is a relative value to the original polarizer of Example 1.

[0084] (3) Determine the Raman spectrum at 158 ​​cm⁻¹ -1 and 162cm -1 Is there a "V"-shaped I5 between them? - If a vibration peak is not present, it is rated as good and marked as ○; otherwise, it is rated as poor and marked as ×.

[0085] (4) If the polarization degree of the original polarizer is ≥99.99, it is rated as good and recorded as ○; otherwise, it is rated as poor and recorded as ×. If the polarization degree is ≥99.9 after high temperature and high temperature and high humidity treatment, it is rated as good and recorded as ○; otherwise, it is rated as poor and recorded as ×.

[0086] (5) If the cross transmittance at 700nm of the original polarizer is ≤0.05%, it is rated as good and recorded as ○; otherwise, it is rated as poor and recorded as ×. After high temperature and high temperature and high humidity treatment, the cross transmittance at 700nm is ≤1%, which is rated as good and recorded as ○.

[0087] (6) Polarizing films that have undergone high temperature and high humidity treatment and show no visible cracks when viewed with the naked eye are rated as good and marked as ○; otherwise, they are rated as bad and marked as ×.

[0088] The test results are shown in Table 2:

[0089] Table 2

[0090]

[0091]

[0092] As shown in Table 2, the polarizer produced by this invention, which contains a high-valence metal cation additive in one or more solutions of the swelling solution, dyeing solution, crosslinking solution, stretching solution, and color-correcting solution, exhibits good durability. The polarizer maintains a high degree of polarization under high temperature and high humidity conditions, and does not crack. - It exhibits linearity and good stability, without any red light leakage.

[0093] The manufacturing method provided by this invention can produce polarizing films with excellent durability, especially excellent thermal stability, thereby effectively solving the problems of polarization degree decrease, cracking and red light leakage of polarizers at high temperatures.

[0094] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-durability polarizing film, characterized in that, Includes the following steps: Polyvinyl alcohol optical films are subjected to swelling, dyeing, crosslinking, stretching, and color correction processes; wherein a high-valence metal cation additive is added in one or more of the swelling, dyeing, crosslinking, stretching, and color correction processes. The optical film is then post-processed to obtain a polarizer; The high-valence metal cation additive is any one or a combination of soluble Zr(Ⅳ), Fe(III), Cr(Ⅲ), and Ti(Ⅳ); The pH of the solution containing the high-valence metal cation additive is 2-3.

2. The method for preparing a high-durability polarizer according to claim 1, characterized in that, Zr(Ⅳ) includes ZrOCl2; Fe(III) includes FeCl3 and Fe2(SO4)3; Ti(Ⅳ) includes TiCl4; Cr(Ⅲ) includes CrI3, Cr2(SO4)3 and CrCl3.

3. The method for preparing a high-durability polarizer according to claim 1, characterized in that, In transitional high-valence metal cation additives, Fe(III) is specifically added to KI-free swelling solutions or crosslinking solutions.

4. The method for preparing a high-durability polarizer according to claim 1, characterized in that, The concentration of transition high-valence metal ions in the solution containing the transition high-valence metal cation additive is 0.05–0.5 mol / L.

5. The method for preparing a high-durability polarizer according to claim 1, characterized in that, The pH value was adjusted using an inorganic acid with pK < 3.

6. The method for preparing a high-durability polarizer according to claim 1, characterized in that, The solution used in the processing of polyvinyl alcohol optical films contains KI, with a KI mass percentage of 1% to 2%.

7. A high-durability polarizing film, characterized in that, It is prepared by any one of the preparation methods of claims 1 to 6.

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