Release film, preparation method and polarizing plate applying release film

Abstract

According to the release film, modified silicone oil is adopted as a main agent, hydroxyl hydrophilic groups are introduced into the modified silicone oil, the hydrophilicity of the silicone oil is improved, the silicone oil is made to be soluble in water, the modified silicone oil is matched with a curing agent, the curing agent and active groups in the modified silicone oil are subjected to a cross-linking reaction, and the release film is formed. And further, the water-type release film is smoothly prepared. In the preparation process of the release film, no organic solvent is involved, no harmful gas is generated, and the environment-friendly requirement is met.

Description

Technical Field

[0001] The present application relates to the field of liquid crystal display technology, and in particular to a release film, a preparation method and a polarizing plate using the release film. Background Art

[0002] In the process of continuous evolution of modern liquid crystal display technology, liquid crystal screens have dominated the display field due to their advantages such as lightness, thinness and energy saving. As the core component of liquid crystal screens, polarizing plates are attached to the upper and lower sides of liquid crystal glass, and cooperate with the rotation of liquid crystal to control the passage of light and achieve the display effect. Polarizing plates are mainly composed of multiple layers of film materials such as PVA film, TAC film, protective film, release film and pressure-sensitive adhesive. During the manufacturing, transportation and assembly process, in order to ensure the perfect fit between the polarizing plate and the liquid crystal screen, a layer of release film needs to be attached to the surface of the main display material.

[0003] Environmental protection is the cornerstone of a country's sustainable development and is related to the people's happy life. Clients have increasingly stringent requirements for environmental emissions in the production and manufacturing process, hoping to accelerate the pace of environmental emissions and achieve a win-win situation for economic and environmental benefits.

[0004] Among the many film materials of polarizing plates, release films are relatively easy to innovate in green technology. Traditional release films are prepared by drying a coating liquid with an organic solvent (such as butanone, methyl isobutyl ketone, toluene, etc.). During the drying process, the coating liquid produces a large amount of organic waste gas, which not only affects air quality and destroys ecological balance, but may also endanger human health. Although RTO technology is often used for treatment, it is not effective in treating high-concentration organic waste gas and may produce secondary pollutants such as nitrogen oxides and dioxins.

[0005] Therefore, developing environmentally friendly release films to replace traditional release film products with organic solvent coating liquids has important practical significance for reducing organic waste gas emissions and lowering environmental risks. Summary of the invention

[0006] The technical problem to be solved by the present application is to provide an environmentally friendly release film to prevent organic waste gas from polluting the environment.

[0007] To solve the above technical problems, the present application can be implemented through the following technical solutions:

[0008] The present application provides a release film, wherein the release film is prepared from a release film coating liquid, and the release film coating liquid is prepared by the following steps:

[0009] In parts by weight, 30 to 90 parts of modified silicone oil, 0.02 to 0.4 parts of catalyst, 0.1 to 1.5 parts of surfactant, 0.1 to 0.7 parts of curing agent, and 150 to 270 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid.

[0010] Based on the above scheme, the release film coating liquid is prepared from modified silicone oil, catalyst, surfactant, curing agent and water. The modified silicone oil is the main component, which gives the release film good release performance; the catalyst promotes the reaction; the surfactant improves the wettability and uniformity of the coating liquid; the curing agent reacts with the modified silicone oil to form a cross-linked structure to improve the performance of the film; water is used as a solvent. When preparing the release film coating liquid, the components are mixed and stirred evenly and then left to stand to allow the reaction to proceed fully, thereby obtaining a stable release film coating liquid.

[0011] As a further improvement of the present application, the modified silicone oil is prepared by the following steps: 50 to 80 parts of silicone oil and 0.1 to 0.4 parts of peroxide initiator are added into a reaction vessel, stirred and heated, so that the temperature in the reaction vessel is controlled at 60°C to 80°C, and 20 to 35 parts of acrylic acid are slowly dripped into the reaction vessel under continuous stirring, and the dripping speed is 1ml / min to 2ml / min. After the dripping is completed, the reaction is fully reacted, and the excess material is removed after the reaction is completed to obtain the modified silicone oil. In the preparation of the modified silicone oil: silicone oil and acrylic acid react under the action of peroxide initiator, hydroxyl hydrophilic groups are introduced, the hydrophilicity of silicone oil is improved, and it is soluble in water, which is conducive to the preparation of environmentally friendly coating liquid. The reaction principle is: the peroxide initiator decomposes to produce free radicals, which trigger the reaction of silicone oil and acrylic acid, and the carboxyl group and other groups of acrylic acid are grafted onto the silicone oil molecular chain to form modified silicone oil.

[0012] As a further improvement of the present application, the silicone oil is at least one of dimethyl silicone oil, vinyl silicone oil, methyltrifluoropropyl silicone oil, and methyl hydrogen-containing silane.

[0013] As a further improvement of the present application, the catalyst is at least one of chloroplatinic acid-divinyltetramethyldisiloxane, chloroplatinic acid-isopropanol, and chloroplatinic acid-diethyl phthalate.

[0014] As a further improvement of the present application, the surfactant is a silicone leveling agent or an acrylate leveling agent, preferably, the surfactant is at least one of BASF BYK307, BASF BYK3700, and DIC GRANDIC PC4100. As a further improvement of the present application, the curing agent is HDI produced by BASF.

[0015] As a further improvement of the present application, the peroxidation initiator is a product of BASF, model number PMBK.

[0016] To achieve the above-mentioned purpose, the present application also provides a method for preparing a release film, comprising the following steps: stirring the release film coating liquid for 30 minutes, coating it on a corona-treated PET substrate, drying it at 230°C to 270°C for 90s to 150s, and then aging it at 40°C to 60°C for 36h to 60h to obtain a release film.

[0017] As a further improvement of the present application, the aging temperature is 45° C. and the aging time is 48 hours.

[0018] To achieve the above object, the present application also provides a polarizing plate, which includes the release film described above or the release film prepared by the preparation method described above.

[0019] The beneficial effects of the present application are as follows: the present application uses acrylic acid and peroxide catalyst to modify silicone oil, introduces hydroxyl hydrophilic groups into silicone oil, improves the hydrophilicity of silicone oil, makes it soluble in water, and is easy to prepare into environmentally friendly water-based coating liquid. The method abandons traditional organic solvents, reduces harmful gas emissions, does not require RTO treatment, saves space and costs, and meets environmental protection requirements. DETAILED DESCRIPTION

[0020] The present application is described in detail below. However, these embodiments do not limit the present application, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all included in the protection scope of the present application.

[0021] In order to verify that the release film provided in this application has excellent effects, the following examples are provided:

[0022] Example 1

[0023] The present embodiment provides a modified silicone oil, which is prepared by the following steps: adding 50 parts of dimethyl silicone oil and 0.1 parts of peroxide initiator into a reaction container, stirring and heating, so that the temperature in the reaction container is controlled at 60° C., slowly dropping 20 parts of acrylic acid into the reaction container under continuous stirring, and the dropping rate is 1 ml / min. After the dropping is completed, fully react for 3 hours. During the reaction, closely observe the state of the reaction mixture, such as color change, viscosity change, etc. After the reaction is completed, stop heating and stirring. If there is unreacted acrylic acid in the reaction product, it can be removed by vacuum distillation. The reaction product is filtered to remove possible solid impurities, and finally the modified silicone oil is obtained.

[0024] The present embodiment also provides a release film, which is prepared by the following steps: in parts by weight, 30 parts of the modified silicone oil prepared in this embodiment, 0.02 parts of diethyl chloroplatinic acid-phthalate, 0.1 parts of GRANDIC PC4100, 0.1 parts of HDI, and 150 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid.

[0025] The release film coating liquid was stirred for 30 minutes, and then coated on the corona-treated PET substrate using a scraper at a speed of 40 m / min, dried at 230° C. for 150 seconds, and then aged at 40° C. for 36 hours to obtain a release film.

[0026] This embodiment also provides a method for preparing a polarizing plate using the above release film, which specifically includes the following steps:

[0027] First, the original PVA film is swollen, dyed, bridged, stretched, washed, fixed and dried to obtain polarized light; the polarized light is bonded to the upper and lower protective films by UV glue to obtain the original reverse polarizer. The photoinitiator in the UV glue absorbs ultraviolet light and generates active free radicals or cations, which triggers monomer polymerization and cross-linking chemical reactions, so that the UV glue is converted from liquid to solid within a few seconds.

[0028] Secondly, the original reverse polarizing plate is unwound, the release film is unwound at the same time, the PE protective film is peeled off, and a pressure-sensitive adhesive is coated on the release film. After drying in a multi-section oven, the release film is attached to the lower protective film to obtain a semi-finished polarizing plate.

[0029] Finally, the semi-finished polarizing plate is unrolled, and the PET protective film with a functional layer is attached. After being reeled up, it is sent to the cutting station for cutting and edge grinding to obtain the finished polarizing plate.

[0030] Example 2

[0031] The present embodiment provides a modified silicone oil, which is prepared by the following steps: adding 80 parts of vinyl silicone oil and 0.4 parts of PMBK into a reaction container, stirring and heating to control the temperature in the reaction container at 80°C, slowly dropping 35 parts of acrylic acid into the reaction container under continuous stirring at a rate of 2 ml / min, fully reacting after the dropwise addition, and fully reacting for 3 hours. During the reaction, closely observe the state of the reaction mixture, such as color change, viscosity change, etc. After the reaction is completed, stop heating and stirring. If there is unreacted acrylic acid in the reaction product, it can be removed by reduced pressure distillation. The reaction product is filtered to remove possible solid impurities, and finally the modified silicone oil is obtained.

[0032] The present embodiment also provides a release film, which is prepared by the following steps: in parts by weight, 90 parts of the modified silicone oil prepared in the present embodiment, 0.4 parts of chloroplatinic acid-divinyltetramethyldisiloxane, 1.5 parts of BYK307, 0.7 parts of HDI, and 270 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid.

[0033] The release film coating liquid was stirred for 30 minutes, and then coated on the corona-treated PET substrate using a scraper at a speed of 40 m / min, dried at 270° C. for 90 seconds, and then aged at 60° C. for 60 hours to obtain a release film.

[0034] This embodiment also provides a method for preparing a polarizing plate using the above release film, which specifically includes the following steps:

[0035] First, the original PVA film is swollen, dyed, bridged, stretched, washed, fixed and dried to obtain polarized light; the polarized light is bonded to the upper and lower protective films by UV glue to obtain the original reverse polarizer. The photoinitiator in the UV glue absorbs ultraviolet light and generates active free radicals or cations, which triggers monomer polymerization and cross-linking chemical reactions, so that the UV glue is converted from liquid to solid within a few seconds.

[0036] Secondly, the original reverse polarizing plate is unwound, the release film is unwound at the same time, the PE protective film is peeled off, and a pressure-sensitive adhesive is coated on the release film. After drying in a multi-section oven, the release film is attached to the lower protective film to obtain a semi-finished polarizing plate.

[0037] Finally, the semi-finished polarizing plate is unrolled, and the PET protective film with a functional layer is attached. After being reeled up, it is sent to the cutting station for cutting and edge grinding to obtain the finished polarizing plate.

[0038] Example 3

[0039] The present embodiment provides a modified silicone oil, which is prepared by the following steps: adding 60 parts of methyl trifluoropropyl silicone oil and 0.25 parts of PMBK into a reaction container, stirring and heating to control the temperature in the reaction container at 80° C., slowly dropping 28 parts of acrylic acid into the reaction container under continuous stirring at a rate of 2 ml / min, fully reacting after the dropwise addition, and fully reacting for 5 hours. During the reaction, closely observing the state of the reaction mixture, such as color change, viscosity change, etc., after the reaction is completed, stopping heating and stirring, if there is unreacted acrylic acid in the reaction product, it can be removed by reduced pressure distillation, filtering the reaction product to remove possible solid impurities, and finally obtaining the modified silicone oil.

[0040] The present embodiment also provides a release film, which is prepared by the following steps: in parts by weight, 56 parts of the modified silicone oil prepared in this embodiment, 0.2 parts of chloroplatinic acid-isopropyl alcohol, 0.8 parts of BYK3700, 0.4 parts of HDI, and 210 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid.

[0041] The release film coating liquid was stirred for 30 minutes, and then coated on the corona-treated PET substrate using a scraper at a speed of 40 m / min, dried at 250° C. for 120 seconds, and then aged at 45° C. for 48 hours to obtain a release film.

[0042] This embodiment also provides a method for preparing a polarizing plate using the above release film, which specifically includes the following steps:

[0043] First, the original PVA film is swollen, dyed, bridged, stretched, washed, fixed and dried to obtain polarized light; the polarized light is bonded to the upper and lower protective films by UV glue to obtain the original reverse polarizer. The photoinitiator in the UV glue absorbs ultraviolet light and generates active free radicals or cations, which triggers monomer polymerization and cross-linking chemical reactions, so that the UV glue is converted from liquid to solid within a few seconds.

[0044] Secondly, the original reverse polarizing plate is unwound, the release film is unwound at the same time, the PE protective film is peeled off, and a pressure-sensitive adhesive is coated on the release film. After drying in a multi-section oven, the release film is attached to the lower protective film to obtain a semi-finished polarizing plate.

[0045] Finally, the semi-finished polarizing plate is unrolled, and the PET protective film with a functional layer is attached. After being reeled up, it is sent to the cutting station for cutting and edge grinding to obtain the finished polarizing plate.

[0046] Example 4

[0047] The difference between this embodiment and embodiment 3 is that methyl hydrogen-containing silane is used to replace methyl trifluoropropyl silicone oil.

[0048] Comparative Example 1

[0049] This comparative example also provides a release film, which is prepared by the following steps: by weight, 60 parts of methyl trifluoropropyl silicone oil, 0.25 parts of PMBK, 0.2 parts of chloroplatinic acid-isopropyl alcohol, 0.8 parts of BYK3700, 0.4 parts of HDI, and 100 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid. After observation, the release film coating liquid has a stratification phenomenon and cannot be coated.

[0050] Comparative Example 2

[0051] The comparative example provides a modified silicone oil, which is prepared by the following steps: adding 60 parts of methyl trifluoropropyl silicone oil and 0.25 parts of PMBK into a reaction container, stirring and heating to control the temperature in the reaction container at 80°C, slowly dropping 28 parts of acrylic acid into the reaction container under continuous stirring at a rate of 2 ml / min, fully reacting after the dropwise addition, and fully reacting for 5 hours. During the reaction, closely observing the state of the reaction mixture, such as color change, viscosity change, etc., after the reaction is completed, stopping heating and stirring, if there is unreacted acrylic acid in the reaction product, it can be removed by a reduced pressure distillation method, filtering the reaction product to remove possible solid impurities, and finally obtaining the modified silicone oil.

[0052] This comparative example also provides a release film, which is prepared by the following steps: by weight, 75 parts of the modified silicone oil prepared in this comparative example, 0.2 parts of chloroplatinic acid-isopropyl alcohol, 0.8 parts of BYK3700, and 100 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid.

[0053] After stirring the release film coating liquid for 30 minutes, the release film was coated on the corona-treated PET substrate using a scraper at a speed of 40 m / min, dried at 250° C. for 120 seconds, and then aged at 45° C. for 48 hours to obtain a release film. It was observed that the obtained release film could not form a solid state.

[0054] Comparative Example 3

[0055] The difference between this comparative example and Example 3 is that the release film prepared by the technical solution of the present application is not used, and a commercially available release film is selected to prepare the polarizing plate.

[0056] Comparative Example 4

[0057] The present embodiment provides a modified silicone oil, which is prepared by the following steps: adding 60 parts of methyl trifluoropropyl silicone oil and 0.25 parts of PMBK into a reaction container, stirring and heating to control the temperature in the reaction container at 80° C., slowly dropping 28 parts of acrylic acid into the reaction container under continuous stirring at a rate of 2 ml / min, fully reacting after the dropwise addition, and fully reacting for 5 hours. During the reaction, closely observing the state of the reaction mixture, such as color change, viscosity change, etc., after the reaction is completed, stopping heating and stirring, if there is unreacted acrylic acid in the reaction product, it can be removed by reduced pressure distillation, filtering the reaction product to remove possible solid impurities, and finally obtaining the modified silicone oil.

[0058] The present embodiment also provides a release film, which is prepared by the following steps: in parts by weight, 120 parts of the modified silicone oil prepared in this embodiment, 0.2 parts of chloroplatinic acid-isopropyl alcohol, 0.8 parts of BYK3700, 0.4 parts of HDI, and 210 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid.

[0059] The release film coating liquid was stirred for 30 minutes, and then coated on the corona-treated PET substrate using a scraper at a speed of 40 m / min, dried at 250° C. for 120 seconds, and then aged at 45° C. for 48 hours to obtain a release film.

[0060] The polarizing plates prepared in the above embodiments and comparative examples were subjected to peeling force test, and the specific test method is as follows:

[0061] Initial peel force test specification: 1. Cut the finished product with the mechanical edge facing upward, with a size of 2.5cm*15cm; 2. Then use 31B tape to fix the auxiliary tape and the sample, and roll it gently with a (2KG) manual roller; 3. Turn on the tensile testing machine, select the 180°300mm / min test mode, and finally record the first peak value and average value.

[0062] The test results are shown in Table 1:

[0063] Table 1

[0064]

[0065]

[0066] The excellent release film coating liquid needs to meet the following properties: the average peeling force needs to be controlled at 3-5gf / 25mm, and the initial peeling force is less than 100gf / 25mm. It can be seen from the data in the table that the release film prepared by the technical solution of the present application has excellent peeling performance after being combined with the original reverse polarizer, and has a peeling force comparable to that of the release films commonly sold on the market.

[0067] It should be pointed out that the above is only used to explain the preferred embodiment of the present application, and is not intended to limit the present application in any form. Therefore, any modifications or changes made to the present application under the same inventive spirit should still be included in the scope of protection intended by the present application.

Claims

1. A release film, characterized in that: The release film is prepared from a release film coating liquid, and the release film coating liquid is prepared by the following steps: In parts by weight, 30 to 90 parts of modified silicone oil, 0.02 to 0.4 parts of catalyst, 0.1 to 1.5 parts of surfactant, 0.1 to 0.7 parts of curing agent, and 150 to 270 parts of water are fully mixed, stirred evenly, placed at room temperature, and allowed to stand for 4 hours to obtain a release film coating liquid.

2. The release film according to claim 1, characterized in that: The modified silicone oil is prepared by the following steps: adding 50 to 80 parts of silicone oil and 0.1 to 0.4 parts of a peroxide initiator into a reaction container, stirring and heating to control the temperature in the reaction container at 60° C. to 80° C., slowly dropping 20 to 35 parts of acrylic acid into the reaction container under continuous stirring at a rate of 1 ml / min to 2 ml / min, allowing sufficient reaction after the addition, removing excess substances after the reaction is completed, and obtaining the modified silicone oil.

3. The release film according to claim 2, characterized in that: The silicone oil is at least one of dimethyl silicone oil, vinyl silicone oil, methyl trifluoropropyl silicone oil and methyl hydrogen-containing silane.

4. The release film according to claim 2, characterized in that: The catalyst is at least one of chloroplatinic acid-divinyltetramethyldisiloxane, chloroplatinic acid-isopropanol, and chloroplatinic acid-diethyl phthalate.

5. The release film according to claim 2, characterized in that: The surfactant is an organic silicone leveling agent or an acrylic leveling agent. Preferably, the surfactant is at least one of BYK307, BYK3700, and GRANDIC PC4100.

6. The release film according to claim 2, characterized in that: The curing agent is HDI.

7. The release film according to claim 2, characterized in that: The peroxidation initiator is PMBK.

8. A method for preparing a release film, characterized in that: The method comprises the following steps: stirring the release film coating liquid for 30 minutes, coating it on a corona-treated PET substrate, drying it at 230-270°C for 90-150 seconds, and then aging it at 40-60°C for 36-60 hours to obtain a release film.

9. The method for preparing a release film according to claim 8, characterized in that: The aging temperature is 45° C., and the aging time is 48 hours.

10. A polarizing plate, characterized in that: The polarizing plate comprises the release film according to any one of claims 1 to 7 or the release film prepared by the preparation method according to claim 8 or 9.

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