Modification method of PVA for high-durability polaroid

Abstract

According to the modification method of the PVA for the high-durability polaroid, boric acid and sodium pyruvate are adopted for modification in the three steps of washing, extending and color fixing, so that the PVA can be better crosslinked, the effect of enhancing the water resistance is achieved, then the modified PVA is applied to the polaroid, the water absorption influence of the PVA in the middle layer can be blocked through the high water resistance, and therefore the water resistance of the polaroid is improved. The water-resistant polaroid glue has good water resistance and durability, can solve the problem of poor water resistance of the existing polaroid glue, improves the durability of the polaroid, realizes that the periphery is not blackened in a double-85 reliability experiment for more than 1000 hours, and is suitable for large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical polarizing elements, and particularly relates to a modification method of PVA for high-durability polarizing sheets. BACKGROUND

[0002] In the production of a polarizing sheet, the main raw material is a layer of polyvinyl alcohol film (PVA) combined with two layers of triacetate cellulose (TAC), and the PVA is generated into an optical film with a polarization effect under the conditions of water washing, swelling, dyeing, stretching, cleaning and color fixing.

[0003] High-durability polarizing sheets need to meet the optical indicators and no obvious changes in appearance in the double 85 reliability experiment (85 DEG C, 85 RH %) for 1000 hours, and the super strong weather resistance is applied to the corresponding intelligent display. There are various methods for making high-durability polarizing sheets, and the modified PVA is a very good method for improving the durability.

[0004] In the production process of the polarizing sheet, the three steps (cleaning, stretching and color fixing) of the modified PVA are adjusted by adjusting the amount of the modified substance to modify the PVA, so that the product meeting the requirements of the optical and appearance of the high-durability polarizing sheet can be made. At present, the modified substance used in the three steps of cleaning, stretching and color fixing is boric acid, and the polarizing sheet made of boric acid modified PVA will have obvious blackening (commonly known as PVA shrinkage) at the edge of the polarizing sheet after being soaked in double 80 DEG C water for 0.3 hours, which indicates that the high-durability polarizing sheet made of boric acid has poor water resistance. In addition, the polarizing sheet coated with pressure-sensitive adhesive will have black edges in the four directions during the double 85 (85 DEG C, 85 RH %) reliability experiment for 24 hours.

[0005] Therefore, by adding other modified substances to modify the PVA, the performance of improving the durability of the polarizing sheet is achieved, and the polarizing sheet does not have blackening in the four directions for more than 1000 hours in the double 85 reliability experiment. SUMMARY

[0006] The purpose of the present application is to provide a modification method of PVA for high-durability polarizing sheets on the basis of the prior art, and the PVA is modified by boric acid and sodium pyruvate in the three steps of cleaning, stretching and color fixing, so that the PVA can be better crosslinked to achieve the effect of enhanced water resistance. The modified PVA is applied to the polarizing sheet, the high water resistance can block the water absorption of the PVA in the middle layer, prolong the time of blackening in the four directions, has good water resistance and durability, can solve the problem of poor water resistance of the current polarizing sheet adhesive, improve the performance of the durability of the polarizing sheet, realize the double 85 reliability experiment for more than 1000 hours, and the polarizing sheet does not have blackening in the four directions, and is suitable for large-scale industrial production.

[0007] The technical scheme of the present application is as follows:

[0008] A modification method of PVA for high durability polarizing sheet, mainly comprising washing, extending and fixing color of PVA film, and the washing liquid, the extending liquid and the fixing liquid are all made of deionized water, boric acid and sodium pyruvate.

[0009] In the present application, when washing the PVA film, boric acid and sodium pyruvate are used for modification, and in a preferred embodiment, the washing liquid is made of the following components by weight: 2-3 parts of boric acid, 0.4-1.0 parts of sodium pyruvate and 96.0-98.0 parts of deionized water.

[0010] In a more preferred embodiment, the washing liquid is made of the following components by weight: 2.4-2.6 parts of boric acid, 0.45-0.75 parts of sodium pyruvate and 96.5-97.5 parts of deionized water.

[0011] In a particularly preferred embodiment, the washing liquid is made of the following components by weight: 2.5 parts of boric acid, 0.5-0.7 parts of sodium pyruvate and 96.8-97.0 parts of deionized water.

[0012] For example, when washing the PVA film, boric acid and sodium pyruvate are used for modification, and the washing liquid is made of the following components by weight: 2.5 parts of boric acid, 0.5 parts of sodium pyruvate and 97.0 parts of deionized water.

[0013] For example, when washing the PVA film, boric acid and sodium pyruvate are used for modification, and the washing liquid is made of the following components by weight: 2.5 parts of boric acid, 0.7 parts of sodium pyruvate and 96.8 parts of deionized water.

[0014] In the present application, when extending the PVA film, boric acid and sodium pyruvate are used for modification, and in a preferred embodiment, the extending liquid is made of the following components by weight: 2.0-3.0 parts of boric acid, 0.6-1.6 parts of sodium pyruvate and 95.5-97.5 parts of deionized water.

[0015] In a more preferred embodiment, the extending liquid is made of the following components by weight: 2.4-2.6 parts of boric acid, 0.9-1.4 parts of sodium pyruvate and 96.0-97.0 parts of deionized water.

[0016] In a particularly preferred embodiment, the extending liquid is made of the following components by weight: 2.5 parts of boric acid, 1.0-1.3 parts of sodium pyruvate and 96.2-96.5 parts of deionized water.

[0017] For example, when the PVA film is stretched, boracic acid and sodium pyruvate are used for modification, and the stretching liquid used is made of the following components by weight: 2.5 parts of boracic acid, 1.0 part of sodium pyruvate and 96.5 parts of deionized water.

[0018] For example, when the PVA film is stretched, boracic acid and sodium pyruvate are used for modification, and the stretching liquid used is made of the following components by weight: 2.5 parts of boracic acid, 1.0 part of sodium pyruvate and 96.5 parts of deionized water.

[0019] In the present application, when the PVA film is fixed, boracic acid and sodium pyruvate are used for modification, and in a preferred embodiment, the fixing liquid used is made of the following components by weight: 2.0-3.0 parts of boracic acid, 1.1-2.2 parts of sodium pyruvate and 94.5-97.5 parts of deionized water.

[0020] In a more preferred embodiment, the fixing liquid used is made of the following components by weight: 2.4-2.6 parts of boracic acid, 1.3-2.0 parts of sodium pyruvate and 95.0-96.5 parts of deionized water.

[0021] In a particularly preferred embodiment, the fixing liquid used is made of the following components by weight: 2.5 parts of boracic acid, 1.5-1.8 parts of sodium pyruvate and 95.7-96.0 parts of deionized water.

[0022] For example, when the PVA film is fixed, boracic acid and sodium pyruvate are used for modification, and the fixing liquid used is made of the following components by weight: 2.5 parts of boracic acid, 1.5 parts of sodium pyruvate and 96.0 parts of deionized water.

[0023] For example, when the PVA film is fixed, boracic acid and sodium pyruvate are used for modification, and the fixing liquid used is made of the following components by weight: 2.5 parts of boracic acid, 1.8 parts of sodium pyruvate and 95.7 parts of deionized water.

[0024] The technical solution of the present application has the following advantages:

[0025] The present application provides a modification method of PVA for high-durability polarizing sheet, boracic acid and sodium pyruvate are used for modification in the three steps of washing, stretching and fixing, so that the PVA can be better cross-linked to achieve the effect of enhanced water resistance, and then the modified PVA is applied to the polarizing sheet, the high water resistance can block the water absorption of the intermediate layer PVA, prolong the time of four-week blackening, has good water resistance and durability, can solve the problem of poor water resistance of the current polarizing sheet glue, and improve the performance of the durability of the polarizing sheet, realize the double-85 reliability experiment for more than 1000h, four-week blackening, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a picture of the modified PVA in Example 1 applied to a polarizing sheet immersed in a water bath at 80°C for 4 hours;

[0027] Figure 2 is a picture of the modified PVA in Example 2 applied to a polarizing sheet immersed in a water bath at 80°C for 4 hours;

[0028] Figure 3 is a picture of the modified PVA in Comparative Example 1 applied to a polarizing sheet immersed in a water bath at 80°C for 4 hours;

[0029] Figure 4 is a picture of the modified PVA in Comparative Example 2 applied to a polarizing sheet immersed in a water bath at 80°C for 4 hours;

[0030] Figure 5 is a picture of the modified PVA in Comparative Example 3 applied to a polarizing sheet immersed in a water bath at 80°C for 4 hours;

[0031] Figure 6 is a picture of the modified PVA in Comparative Example 4 applied to a polarizing sheet immersed in a water bath at 80°C for 4 hours. DETAILED DESCRIPTION

[0032] The present application can be better understood in accordance with the following examples. However, it is to be understood that the examples described are merely for the purpose of illustration of the present application and should not be construed to limit the present application as described in the claims.

[0033] Example 1

[0034] A method for modifying PVA for a high-durability polarizing sheet, mainly comprising washing, stretching and fixing a PVA film, wherein the washing, stretching and fixing are performed using a washing solution, a stretching solution and a fixing solution, respectively, and the washing solution, the stretching solution and the fixing solution are prepared by mixing the following components in the amounts shown in the table below:

[0035] The washing solution is prepared by mixing the following components in the amounts shown in the table below: boric acid 2.5 parts, sodium pyruvate 0.5 parts and deionized water 97.0 parts;

[0036] The stretching solution is prepared by mixing the following components in the amounts shown in the table below: boric acid 2.5 parts, sodium pyruvate 1.0 parts and deionized water 96.5 parts;

[0037] The fixing solution is prepared by mixing the following components in the amounts shown in the table below: boric acid 2.5 parts, sodium pyruvate 1.5 parts and deionized water 96.0 parts.

[0038] Example 2

[0039] A method for modifying PVA for a high-durability polarizing sheet, mainly comprising washing, stretching and fixing a PVA film, wherein the washing, stretching and fixing are performed using a washing solution, a stretching solution and a fixing solution, respectively, and the washing solution, the stretching solution and the fixing solution are prepared by mixing the following components in the amounts shown in the table below:

[0040] The water washing solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 0.7 parts and deionized water 96.8 parts;

[0041] The stretching solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 1.3 parts and deionized water 96.2 parts;

[0042] The fixing solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 1.8 parts and deionized water 95.7 parts.

[0043] Comparative Example 1

[0044] A modification method of PVA for high durability polarizing sheet mainly includes water washing, stretching and fixing of PVA film, and during water washing, stretching and fixing,

[0045] The water washing solution is made from the following components in parts by weight: boric acid 2.5 parts and deionized water 97.5 parts;

[0046] The stretching solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 1.0 parts and deionized water 96.5 parts;

[0047] The fixing solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 1.5 parts and deionized water 96.0 parts.

[0048] Comparative Example 2

[0049] A modification method of PVA for high durability polarizing sheet mainly includes water washing, stretching and fixing of PVA film, and during water washing, stretching and fixing,

[0050] The water washing solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 0.5 parts and deionized water 97.0 parts;

[0051] The stretching solution is made from the following components in parts by weight: boric acid 2.5 parts and deionized water 97.5 parts;

[0052] The fixing solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 1.5 parts and deionized water 96.0 parts.

[0053] Comparative Example 3

[0054] A modification method of PVA for high durability polarizing sheet mainly includes water washing, stretching and fixing of PVA film, and during water washing, stretching and fixing,

[0055] The water washing solution is made from the following components in parts by weight: boric acid 2.5 parts, sodium pyruvate 0.5 parts and deionized water 97.0 parts;

[0056] The washing liquid is made from the following components by weight: boric acid 2.5 parts, sodium pyruvate 0.3 parts and deionized water 97.2 parts;

[0057] The fixing liquid is made from the following components by weight: boric acid 2.5 parts and deionized water 97.5 parts.

[0058] Comparative Example 4

[0059] A modification method of PVA for high-durability polarizing sheet, mainly including washing, stretching and fixing PVA film, during washing, stretching and fixing,

[0060] The washing liquid is made from the following components by weight: boric acid 2.5 parts, sodium pyruvate 0.3 parts and deionized water 97.2 parts;

[0061] The washing liquid is made from the following components by weight: boric acid 2.5 parts, sodium pyruvate 0.3 parts and deionized water 97.2 parts;

[0062] The fixing liquid is made from the following components by weight: boric acid 2.5 parts, sodium pyruvate 1.5 parts and deionized water 96.5 parts.

[0063] Table 1 Composition of washing liquid, stretching liquid and fixing liquid in examples and comparative examples

[0064] The modified PVA in examples and comparative examples is applied to polarizing sheet, and the test results are analyzed as follows:

[0065] The modified PVA in examples and comparative examples is applied to polarizing sheet, and the water resistance is tested by immersing in water bath at 80℃ for 1-4 hours, and the relevant experimental data are shown in Table 2.

[0066] Table 2 Water resistance data of modified PVA in examples and comparative examples after being applied to polarizing sheet

[0067]

[0068] The above examples are only used to illustrate the technical solutions of the present application, rather than limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that it is still possible to modify the technical solutions recorded in the foregoing examples, or to make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for modifying PVA for high-durability polarizing films, characterized in that, The process mainly involves washing, stretching, and fixing the PVA film. The washing solution, stretching solution, and fixing solution used in the washing, stretching, and fixing processes are all made of deionized water, boric acid, and sodium pyruvate.

2. The modification method of PVA for high-durability polarizing films according to claim 1, characterized in that, The washing solution is made from the following components in parts by weight: 2.0-3.0 parts boric acid, 0.4-1.0 parts sodium pyruvate, and 96.0-98.0 parts deionized water.

3. The method for modifying PVA for high-durability polarizing films according to claim 2, characterized in that, The washing solution is made from the following components in parts by weight: 2.4-2.6 parts boric acid, 0.45-0.75 parts sodium pyruvate, and 96.5-97.5 parts deionized water.

4. The modification method of PVA for high-durability polarizing films according to claim 3, characterized in that, The washing solution is made from the following components in parts by weight: 2.5 parts boric acid, 0.5-0.7 parts sodium pyruvate, and 96.8-97.0 parts deionized water.

5. The method for modifying PVA for high-durability polarizing films according to claim 1, characterized in that, The extension solution is made of the following components in parts by weight: 2.0-3.0 parts boric acid, 0.6-1.6 parts sodium pyruvate and 95.5-97.5 parts deionized water.

6. The method for modifying PVA for high-durability polarizing films according to claim 5, characterized in that, The extension liquid is made of the following components in parts by weight: 2.4-2.6 parts boric acid, 0.9-1.4 parts sodium pyruvate and 96.0-97.0 parts deionized water.

7. The method for modifying PVA for high-durability polarizing films according to claim 6, characterized in that, The extension solution is made of the following components in parts by weight: 2.5 parts boric acid, 1.0-1.3 parts sodium pyruvate and 96.2-96.5 parts deionized water.

8. The method for modifying PVA for high-durability polarizing films according to claim 1, characterized in that, The fixing solution is made of the following components in parts by weight: 2.0-3.0 parts boric acid, 1.1-2.2 parts sodium pyruvate and 94.5-97.5 parts deionized water.

9. The method for modifying PVA for high-durability polarizing films according to claim 8, characterized in that, The fixing solution is made of the following components in parts by weight: 2.4-2.6 parts boric acid, 1.3-2.0 parts sodium pyruvate and 95.0-96.5 parts deionized water.

10. The method for modifying PVA for high-durability polarizing films according to claim 9, characterized in that, The fixing solution is made of the following components in parts by weight: 2.5 parts boric acid, 1.5-1.8 parts sodium pyruvate and 95.8-96.0 parts deionized water.

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