A method for producing a high-transparency polyvinyl alcohol solution for a PVA optical film
By employing saponification, water washing, staged deoxygenation, and heating methods, combined with plasticizers and surfactants, the problem of insufficient transparency in polyvinyl alcohol solutions was solved, enabling the preparation of highly transparent polyvinyl alcohol solutions and improving the haze performance of PVA optical films.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI WANWEI UPDATED HIGH TECH MATERIAL CO LTD
- Filing Date
- 2023-11-16
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies cannot improve transparency while maintaining a concentration of 25%-30% during the preparation of polyvinyl alcohol solutions, resulting in PVA optical films failing to meet haze requirements.
A highly transparent polyvinyl alcohol solution was prepared by using saponification, water washing, staged deoxygenation, and staged heating methods, combined with the use of plasticizers and surfactants, and by deoxygenating multiple times and controlling the dissolution temperature.
The transparency of the polyvinyl alcohol solution was significantly improved, ensuring the quality of the PVA optical film and meeting the requirements of optical thin films.
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Figure CN117510897B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of PVA thin film manufacturing technology, specifically relating to a method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films. Background Technology
[0002] New display technologies, represented by liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs), occupy an extremely important position in fields such as people's livelihood, high technology, and military defense. Among them, polyvinyl alcohol (PVA) optical film is one of the key materials in the manufacture of LCDs and OLEDs, accounting for about 10% of the cost of polarizers, and is a key material that determines the display quality.
[0003] PVA optical films are made by casting or coating a polyvinyl alcohol resin solution, followed by drying. Therefore, the properties of the polyvinyl alcohol solution directly affect the properties of the finished film. Haze is an important optical indicator of PVA optical films, and the transparency of the polyvinyl alcohol solution is a crucial factor directly affecting the haze of the PVA optical film. Therefore, preparing a highly transparent polyvinyl alcohol solution is key. While maintaining a polyvinyl alcohol solution concentration of 25%–30%, increasing the transparency of the polyvinyl alcohol solution helps reduce film haze. Currently, the most common methods to improve solution transparency are reducing the solution concentration or adding additives, but neither of these methods can meet the requirements for producing PVA optical films. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films, in order to solve the problem that in the prior art, the transparency of the polyvinyl alcohol solution cannot be improved while ensuring the concentration of the polyvinyl alcohol solution is 25%-30%.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0007] S1. 100 parts by weight of polyvinyl alcohol powder and 100-400 parts by weight of alkaline solution were saponified for 1 hour under stirring. After the reaction, the product was washed with ultrapure water, centrifuged and collected, and the first deoxygenation was carried out during the centrifugation process.
[0008] S2. Add 200-400 parts by weight of ultrapure water to the dissolving vessel for a second deoxygenation; then add 0.01-0.3 parts by weight of plasticizer and 0.01-0.3 parts by weight of surfactant to the dissolving vessel. Under stirring conditions, place the product collected by centrifugation in S1 into the dissolving vessel for a third deoxygenation; remove the oxygen from the air introduced by the raw materials during the water washing and centrifugation process.
[0009] S3. Use the jacket of the dissolving vessel to heat the material inside the vessel to 70-120℃ for the fourth deoxygenation;
[0010] S4. Steam is introduced into the dissolving vessel, and the temperature inside the vessel is raised to 110-180℃ under stirring. The mixture is stirred at a constant temperature for 6 hours to dissolve the material inside the vessel. After standing to remove bubbles, a polyvinyl alcohol solution is obtained.
[0011] Furthermore, the mass fraction of the alkaline solution in S1 is 10%.
[0012] Furthermore, the degree of polymerization of the polyvinyl alcohol powder in S1 is 2800.
[0013] Furthermore, the alkaline solution in S1 is a potassium hydroxide or sodium hydroxide solution.
[0014] Furthermore, the temperature of the alkaline solution in S1 is 10-50℃.
[0015] Furthermore, the temperature of the ultrapure water in S1 is 10-50℃.
[0016] Furthermore, the number of water washes in S1 is 0-10 times.
[0017] Furthermore, the stirring frequency in S1 is 50Hz, the stirring frequency in S2 is 35Hz, and the stirring frequency in S4 is 35Hz.
[0018] Furthermore, the plasticizer in S2 is any one of polyols or ethers, and preferably, the plasticizer is any one of propylene glycol or glycerol.
[0019] Furthermore, the surfactant in S2 is one or more of anionic surfactants or nonionic surfactants.
[0020] Furthermore, the surfactant comprises polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide in a mass ratio of 12:7.
[0021] Furthermore, the methods for the first, second, third, and fourth deoxygenation include the following steps: introducing nitrogen gas with a purity ≥99.9% and a pressure of 50-200 kPa into the system.
[0022] Furthermore, the nitrogen gas introduction times for the first, second, third, and fourth deoxygenation processes are 0.5-2h, 0.5-2h, 0.5-2h, and 0.5-2h, respectively.
[0023] Furthermore, the jacket heating rate in S3 is 0.5℃ / min.
[0024] Furthermore, the water vapor pressure in S4 is 300-500 kPa.
[0025] As a preferred embodiment of the present invention:
[0026] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0027] S1. 100 parts by weight of polyvinyl alcohol powder and 100-400 parts by weight of 10% alkaline solution are subjected to saponification reaction at a stirring frequency of 50 Hz for 1 hour, and the temperature of the alkaline solution is 20-40℃. After the reaction, the product is washed 1-6 times with ultrapure water at a temperature of 20-40℃. During the process of collecting the product by centrifugation, nitrogen gas with a pressure of 70-150 kPa is introduced into the gas outlet of the centrifuge for the first deoxygenation. The purity of the nitrogen gas is ≥99.9%, and the deoxygenation time is 0.5-2 hours.
[0028] S2. Add 200-400 parts by weight of ultrapure water to the dissolving vessel, and purge with nitrogen gas at a pressure of 70-150 kPa and a purity of ≥99.9% for a second deoxygenation, with a deoxygenation time of 0.5-2 h. Add 0.01-0.3 parts by weight of plasticizer, 0.01-0.3 parts by weight of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide mixed in a mass ratio of 12:7 to the dissolving vessel, and start stirring at a frequency of 35 Hz. Then add the product collected by centrifugation in S1, and purge with nitrogen gas at a pressure of 70-150 kPa and a purity of ≥99.9% for a third deoxygenation, with a deoxygenation time of 0.5-2 h.
[0029] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 70-120℃ at a heating rate of 0.5℃ / min, and introduce gas at a pressure of 70-150KPa; perform a fourth deoxygenation with nitrogen gas of ≥99.9% purity for 0.5-2h.
[0030] S4. Steam is introduced into the dissolving vessel at a pressure of 300-500 kPa. The material in the vessel is heated to 110-180°C at a stirring frequency of 35 Hz and stirred at a constant temperature for 6 hours to completely dissolve the material. After standing to remove bubbles, a high-transparency polyvinyl alcohol solution is obtained.
[0031] The beneficial effects of this invention are:
[0032] 1. This invention provides a method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films. By combining saponification, water washing, staged deoxygenation, and staged heating, the transparency of the polyvinyl alcohol solution can be significantly improved, and the concentration of the prepared polyvinyl alcohol solution is guaranteed to be 25%-30%, which meets the requirements of PVA optical films for optical applications.
[0033] 2. In this invention, the saponification of polyvinyl alcohol in a 10% alkaline solution is performed to increase the degree of hydrolysis of the raw material. A low degree of hydrolysis makes the PVA optical film more prone to coloring. Water washing is performed to remove residual alkali from the saponification process, impurities in the raw material, and to pre-swell the raw material, facilitating subsequent dissolution.
[0034] 3. The present invention employs staged deoxygenation in the dissolving tank to prevent excessive oxygen in the water and oxygen carried into the tank during material feeding, which could cause the polyvinyl alcohol solution to turn yellow during dissolution. Finally, nitrogen is used for deoxygenation again when the polyvinyl alcohol is partially dissolved. This is because the raw material is granular, and oxygen cannot be removed from it when it is not fully dissolved. Performing deoxygenation again when the PVA resin is in a semi-dissolved state ensures thorough deoxygenation, thereby improving the transparency of the polyvinyl alcohol.
[0035] 4. The present invention employs a staged heating method because directly using jacket heating for dissolution results in a prolonged and uneven dissolution of polyvinyl alcohol. Initially, directly using steam heating would cause the dissolution vessel temperature to become too high, resulting in yellowing of the material and a low concentration of the polyvinyl alcohol solution. Therefore, a staged heating method combining jacket heating and steam heating is used for dissolution. During the steam heating stage, an appropriate amount of steam is added to the vessel using a steam coil (adjusted according to the concentration meter), which can shorten the dissolution time while maintaining a certain concentration (25%-30%). Attached Figure Description
[0036] The invention will now be further described with reference to the accompanying drawings.
[0037] Figure 1 This is a flowchart of the preparation process of the present invention. Detailed Implementation
[0038] 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.
[0039] Example 1
[0040] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps:
[0041] S1. 100 parts by weight of polyvinyl alcohol powder and 200 parts by weight of 10% NaOH solution were subjected to saponification reaction at a stirring frequency of 50 Hz for 1 h. The temperature of NaOH solution was 30℃. After the reaction, the product was washed twice with ultrapure water at 30℃. The product was collected by centrifugation. During the centrifugation process, nitrogen gas with a pressure of 110 kPa and a purity of 99.9% was introduced into the centrifuge outlet for the first deoxygenation (dehydration and deoxygenation) for 120 min.
[0042] S2. Add 300 parts by weight of ultrapure water to the dissolving vessel. Introduce nitrogen gas with a pressure of 110 kPa and a purity of 99.9% into the dissolving vessel for a second deoxygenation (gas replacement deoxygenation) for 60 min. Add 0.15 parts by weight of glycerol, 0.1 parts by weight of a combination surfactant of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide (the mass ratio of polyoxyethylene lauryl ether sulfate to lauric acid diethanolamide is 12:7) into the dissolving vessel and start stirring at a frequency of 35 Hz. Then add the product collected by centrifugation in S1 into the dissolving vessel and introduce nitrogen gas with a pressure of 110 kPa and a purity of 99.9% into the dissolving vessel for a third deoxygenation (dissolving vessel deoxygenation) for 30 min.
[0043] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 100℃ (i.e., in a semi-molten state) at a heating rate of 0.5℃ / min. Then, introduce nitrogen gas with a pressure of 110KPa and a purity of 99.9% for the fourth deoxygenation, which takes 30 minutes.
[0044] S4. Steam at a pressure of 400 kPa is introduced into the dissolving vessel. The material in the vessel is heated to 160°C with a stirring frequency of 35 Hz. The steam is then stopped and the vessel is stirred at a constant temperature for 6 hours to completely dissolve the material. After standing to remove bubbles, a 25% polyvinyl alcohol solution is obtained.
[0045] Example 2
[0046] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0047] S1. 100 parts by weight of polyvinyl alcohol powder and 100 parts by weight of 10% KOH solution were subjected to saponification reaction at a stirring frequency of 50 Hz for 1 h. The temperature of the NaOH solution was 20℃. After the reaction, the product was washed 4 times with ultrapure water at 20℃. The product was collected by centrifugation. During the centrifugation process, nitrogen gas with a pressure of 80 kPa and a purity of 99.9% was introduced into the centrifuge outlet for the first deoxygenation (dehydration and deoxygenation) for 30 min.
[0048] S2. Add 200 parts by mass of ultrapure water to the dissolving vessel. Introduce nitrogen gas with a pressure of 80 kPa and a purity of 99.9% into the dissolving vessel for a second deoxygenation (gas replacement deoxygenation) for 120 min. Add 0.02 parts by mass of propylene glycol, 0.015 parts by mass of a combination surfactant of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide (the mass ratio of polyoxyethylene lauryl ether sulfate to lauric acid diethanolamide is 12:7) into the dissolving vessel and start stirring at a frequency of 35 Hz. Then add the product collected by centrifugation in S1 into the dissolving vessel and introduce nitrogen gas with a pressure of 80 kPa and a purity of 99.9% into the dissolving vessel for a third deoxygenation (dissolving vessel deoxygenation) for 60 min.
[0049] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 80°C at a heating rate of 0.5°C / min, and introduce nitrogen gas with a pressure of 80KPa and a purity of 99.9% for the fourth deoxygenation, with a deoxygenation time of 60min.
[0050] S4. Steam at a pressure of 300 kPa is introduced into the dissolving vessel. The material in the vessel is heated to 110°C with a stirring frequency of 35 Hz. The steam is then stopped and the vessel is stirred at a constant temperature for 6 hours to completely dissolve the material. After standing to remove bubbles, a polyvinyl alcohol solution with a concentration of 26% is obtained.
[0051] Example 3
[0052] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0053] S1. 100 parts by weight of polyvinyl alcohol powder and 400 parts by weight of 10% NaOH solution were subjected to saponification reaction at a stirring frequency of 50 Hz for 1 h. The temperature of NaOH solution was 40℃. After the reaction, the product was washed 4 times with ultrapure water at 40℃. The product was collected by centrifugation. During the centrifugation process, nitrogen gas with a pressure of 150 kPa and a purity of 99.9% was introduced into the centrifuge outlet for the first deoxygenation (dehydration and deoxygenation) for 60 min.
[0054] S2. Add 400 parts by weight of ultrapure water to the dissolving vessel. Introduce nitrogen gas with a pressure of 150 kPa and a purity of 99.9% into the dissolving vessel for a second deoxygenation (gas replacement deoxygenation) for 30 min. Add 0.28 parts by weight of glycerol, 0.25 parts by weight of a combination surfactant of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide (the mass ratio of polyoxyethylene lauryl ether sulfate to lauric acid diethanolamide is 12:7) into the dissolving vessel and start stirring at a frequency of 35 Hz. Then add the product collected by centrifugation in S1 into the dissolving vessel and introduce nitrogen gas with a pressure of 150 kPa and a purity of 99.9% into the dissolving vessel for a third deoxygenation (dissolving vessel deoxygenation) for 120 min.
[0055] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 120°C at a heating rate of 0.5°C / min, and introduce nitrogen gas with a pressure of 150 kPa and a purity of 99.9% for the fourth deoxygenation, with a deoxygenation time of 120 min.
[0056] S4. Introduce steam at a pressure of 500 kPa into the dissolving vessel, heat the material in the vessel to 180°C with a stirring frequency of 35 Hz, stop introducing steam, and stir at a constant temperature for 6 hours to completely dissolve the material in the vessel. Allow it to stand to remove bubbles and obtain a polyvinyl alcohol solution with a concentration of 29%.
[0057] Comparative Example 1
[0058] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0059] S1. 100 parts by weight of polyvinyl alcohol powder and 200 parts by weight of 10% NaOH solution were subjected to saponification reaction at a stirring frequency of 50 Hz for 1 h. The temperature of NaOH solution was 30℃. After the reaction, the product was washed twice with ultrapure water at 30℃ and collected by centrifugation.
[0060] S2. Add 300 parts by weight of ultrapure water to the dissolving vessel, and purge the dissolving vessel with nitrogen gas at a pressure of 7110 kPa and a purity of 99.9% for gas replacement and deoxygenation for 1.2 h; add 0.15 parts by weight of glycerol, 0.1 parts by weight of a combination surfactant of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide (the mass ratio of polyoxyethylene lauryl ether sulfate to lauric acid diethanolamide is 12:7), and start stirring at a frequency of 35 Hz; then add the product collected by centrifugation in S1 to the dissolving vessel;
[0061] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 100℃ at a heating rate of 0.5℃ / min.
[0062] S4. Steam at a pressure of 400 kPa is introduced into the dissolving vessel. The material in the vessel is heated to 160°C with a stirring frequency of 35 Hz. The steam is then stopped and the vessel is stirred at a constant temperature for 6 hours to completely dissolve the material. After standing to remove bubbles, a 25% polyvinyl alcohol solution is obtained.
[0063] Comparative Example 2
[0064] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0065] S1. 100 parts by weight of polyvinyl alcohol powder and 200 parts by weight of 10% NaOH solution were subjected to saponification reaction at a stirring frequency of 50 Hz for 1 h. The temperature of NaOH solution was 30℃. After the reaction, the product was washed twice with ultrapure water at 30℃ and collected by centrifugation.
[0066] S2. Add 300 parts by weight of ultrapure water to the dissolving vessel, and purge the dissolving vessel with nitrogen gas at a pressure of 110 kPa and a purity of 99.9% for gas replacement and deoxygenation for 60 min; add 0.15 parts by weight of glycerol, 0.1 parts by weight of a combination surfactant of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide (the mass ratio of polyoxyethylene lauryl ether sulfate to lauric acid diethanolamide is 12:7), and start stirring at a frequency of 35 Hz; then add the product collected by centrifugation in S1 to the dissolving vessel, and purge the dissolving vessel again with nitrogen gas at a pressure of 110 kPa and a purity of 99.9% for deoxygenation for 30 min;
[0067] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 100℃ at a heating rate of 0.5℃ / min.
[0068] S4. Steam at a pressure of 400 kPa is introduced into the dissolving vessel. The material in the vessel is heated to 160°C with a stirring frequency of 35 Hz. The steam is then stopped and the vessel is stirred at a constant temperature for 6 hours to completely dissolve the material. After standing to remove bubbles, a 25% polyvinyl alcohol solution is obtained.
[0069] Comparative Example 3
[0070] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0071] S1.100 parts by weight of polyvinyl alcohol powder was washed twice with ultrapure water at 30°C. The product was collected by centrifugation. During the centrifugation process, nitrogen gas with a pressure of 110 kPa and a purity of 99.9% was introduced into the centrifuge outlet for the first deoxygenation (dehydration and deoxygenation) for 120 min.
[0072] S2. Add 300 parts by weight of ultrapure water to the dissolving vessel. Introduce nitrogen gas with a pressure of 110 kPa and a purity of 99.9% into the dissolving vessel for a second deoxygenation (gas replacement deoxygenation) for 60 min. Add 0.15 parts by weight of glycerol, 0.1 parts by weight of a combination surfactant of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide (the mass ratio of polyoxyethylene lauryl ether sulfate to lauric acid diethanolamide is 12:7) into the dissolving vessel and start stirring at a frequency of 35 Hz. Then add the product collected by centrifugation in S1 into the dissolving vessel and introduce nitrogen gas with a pressure of 110 kPa and a purity of 99.9% into the dissolving vessel for a third deoxygenation (dissolving vessel deoxygenation) for 30 min.
[0073] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 100℃ at a heating rate of 0.5℃ / min, and introduce nitrogen gas with a pressure of 110KPa and a purity of 99.9% for the fourth deoxygenation, with a deoxygenation time of 30min.
[0074] S4. Steam at a pressure of 400 kPa is introduced into the dissolving vessel. The material in the vessel is heated to 160°C with a stirring frequency of 35 Hz. The steam is then stopped and the vessel is stirred at a constant temperature for 6 hours to completely dissolve the material. After standing to remove bubbles, a 25% polyvinyl alcohol solution is obtained.
[0075] Comparative Example 4
[0076] A method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films includes the following steps:
[0077] S1. 100 parts by weight of polyvinyl alcohol powder and 200 parts by weight of 10% NaOH solution were subjected to saponification reaction at a stirring frequency of 50 Hz for 1 h. The temperature of NaOH solution was 30℃. After the reaction, the product was washed twice with ultrapure water at 30℃ and collected by centrifugation.
[0078] S2. Add 300 parts by weight of ultrapure water to the dissolving vessel, add 0.15 parts by weight of glycerol, 0.1 parts by weight of a combination surfactant of polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide (the mass ratio of polyoxyethylene lauryl ether sulfate to lauric acid diethanolamide is 12:7), and start stirring at a frequency of 35 Hz; then add the product collected by centrifugation in S1.
[0079] S3. Using the jacket of the dissolving vessel, heat the material inside the vessel to 100℃ at a heating rate of 0.5℃ / min.
[0080] S4. Steam at a pressure of 400 kPa is introduced into the dissolving vessel. The material in the vessel is heated to 160°C with a stirring frequency of 35 Hz. The steam is then stopped and the vessel is stirred at a constant temperature for 6 hours to completely dissolve the material. After standing to remove bubbles, a 25% polyvinyl alcohol solution is obtained.
[0081] Performance tests were conducted on Examples 1-4 and Comparative Examples 1-4, and the haze of the PVA optical films fabricated from them was measured. The test results are shown in Table 1.
[0082] Table 1
[0083]
[0084] As shown in Table 1, performing staged deoxygenation during the numerical dissolution process of polyvinyl alcohol—deoxygenation with ultrapure water in the dissolution vessel, deoxygenation during water washing and centrifugation, deoxygenation when all PVA resin has just entered the dissolution vessel, and deoxygenation when the PVA resin is in a semi-dissolved state—can significantly improve the transparency of the polyvinyl alcohol solution at a certain concentration, thereby improving the haze of the PVA optical film surface.
[0085] 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.
[0086] 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-transparency polyvinyl alcohol solution for producing PVA optical films, characterized in that, Includes the following steps: S1. 100 parts by weight of polyvinyl alcohol powder and 100-400 parts by weight of 10% alkaline solution were subjected to saponification reaction for 1 hour under stirring. After the reaction, the product was washed with ultrapure water, centrifuged and collected, and the first deoxygenation was carried out during the centrifugation process. S2. Add 200-400 parts by weight of ultrapure water to the dissolving vessel and perform a second deoxygenation; Add 0.01-0.3 parts by weight of plasticizer and 0.01-0.3 parts by weight of surfactant to the dissolving vessel. Under stirring conditions, place the product collected by centrifugation in S1 into the dissolving vessel for a third deoxygenation. S3. The jacket is heated to 70-120℃ at a heating rate of 0.5℃ / min for the fourth deoxygenation. S4. Steam is introduced into the dissolving vessel to raise the temperature inside the vessel to 110-180℃. The mixture is stirred at a constant temperature for 6 hours to dissolve the material inside the vessel. After standing to remove bubbles, a polyvinyl alcohol solution is obtained. The temperature of the alkaline solution in S1 is 10-50℃, and the temperature of the ultrapure water is 10-50℃; The methods for the first, second, third, and fourth deoxygenation processes include the following steps: introducing nitrogen gas with a purity ≥99.9% and a pressure of 50-200 kPa for 0.5-2 hours.
2. The method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films according to claim 1, characterized in that, The alkaline solution in S1 is a potassium hydroxide or sodium hydroxide solution.
3. The method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films according to claim 1, characterized in that, The plasticizer in S2 is any one of polyols or ethers.
4. The method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films according to claim 3, characterized in that, The plasticizer includes propylene glycol or glycerin.
5. The method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films according to claim 1, characterized in that, The surfactant in S2 is one or more of anionic surfactants or nonionic surfactants.
6. The method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films according to claim 5, characterized in that, The surfactant comprises polyoxyethylene lauryl ether sulfate and lauric acid diethanolamide in a mass ratio of 12:
7.
7. The method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films according to claim 1, characterized in that, The water vapor pressure in S4 is 300-500 kPa.
8. The method for preparing a high-transparency polyvinyl alcohol solution for producing PVA optical films according to claim 1, characterized in that, The stirring frequency in S1 is 50Hz, the stirring frequency in S2 is 35Hz, and the stirring frequency in S4 is 35Hz.