High-temperature-resistant antistatic protective film for polaroid and preparation method of high-temperature-resistant antistatic protective film

Abstract

The invention discloses a high-temperature-resistant antistatic protective film for a polaroid and a preparation method of the high-temperature-resistant antistatic protective film. The high-temperature-resistant antistatic protective film for the polaroid is characterized in that the high-temperature-resistant antistatic protective film for the polaroid is formed by compounding a PET (Polyethylene Terephthalate) base material film, an acrylic acid pressure-sensitive adhesive layer and a release film which are sequentially overlapped, the acrylic pressure-sensitive adhesive is formed by mixing a high-temperature-resistant acrylate polymer, a curing agent, an antistatic agent, a flatting agent and a solvent; the high-temperature-resistant acrylate polymer is prepared from an acrylate soft monomer, an acrylate hard monomer, an acrylate functional monomer, a heat-resistant monomer, polyhedral oligomeric silsesquioxane and an initiator through free radical polymerization in a solvent. The preparation method comprises the following steps: coating an acrylic acid pressure-sensitive adhesive on a PET (Polyethylene Terephthalate) base material film, heating and curing to form an acrylic acid pressure-sensitive adhesive layer, covering a release film, and curing to obtain the high-temperature-resistant antistatic protective film for the polaroid. The protective film provided by the invention has the characteristics of low stripping force, low climbing after high temperature, scratch resistance, good antistatic property and the like, and is suitable for being used as a surface protective film of a polaroid.

Description

Technical Field

[0001] The present invention belongs to a protective film for optical display equipment, and relates to a high temperature resistant antistatic protective film for polarizer and a preparation method thereof. The high temperature resistant antistatic protective film prepared by the present invention is particularly suitable for being used as a surface protective film for polarizer. Background Art

[0002] The components of liquid crystal display (LCD) include polarizer, ITO substrate glass, orientation film, liquid crystal material, conductive material, frame glue and gasket, etc. Among them, the role of polarizer is to polarize the light passing through it and provide linear polarization for LCD. As a basic component of flat panel display, polarizer plays a key role in realizing display function and improving display quality.

[0003] During the manufacturing, processing, transportation and assembly of optical components such as polarizers for liquid crystal displays, surface protection films are applied to the surface of the optical components to prevent surface contamination and scratches in subsequent processes. Since polarizers are tested for performance with protective films attached, the adhesive of the surface protection film is required to be firmly attached to the polarizer, and there should be no bubbles or impurities in the adhesive layer.

[0004] After being assembled in a liquid crystal display, the protective film on the surface of the polarizer will be torn off, so the surface protective film needs to have low adhesion. At the same time, in the process of tearing off the surface protective film, the protective film has a high resistance value, which will generate static voltage. In order to prevent the polarizer protective film from being peeled off from the polarizer and causing damage to the circuit components of the liquid crystal display, the adhesive layer of the protective film is required to have a certain resistance value. The resistance of the adhesive layer of the protective film is less than 10 10 Ω, the adhesive layer has an antistatic effect. In addition, when the surface protection film is finally peeled off from optical components such as polarizers and phase difference plates, it is required to be able to peel off quickly without any residue. That is, it is required to be able to peel off quickly even at high speed, and the change in peeling speed has little effect on the adhesive force.

[0005] In addition, the polarizer protective film should also have reliable high temperature resistance, because the polarizer may experience high ambient temperature during transportation or storage. At high temperatures, the small molecules in the adhesive layer can easily migrate to the pores on the surface of the polarizer, which enhances the interfacial bonding force between the pressure-sensitive adhesive and the polarizer, thereby causing an increase in the peeling force, resulting in damage to the polarizer body when the protective film is torn off, which seriously affects the product yield.

[0006] In the prior art, CN 114350285A discloses a new adhesive for polarizer protective film, which uses silane-modified oxide antistatic agent, has excellent antistatic performance, no residual adhesive, no precipitation, no yellowing, and is easy to peel off under high temperature and high humidity environment. However, the number of feeding times is large, the preparation process is complicated, and it is not conducive to production.

[0007] CN112851852A discloses an acrylic polymer for polarizer protective film. The acrylic polymer composition can be used to make a polarizer protective film, which has a certain degree of softness, is resistant to scratching and powdering, will not migrate to the surface of the adhesive layer over time to cause polarizer shadows, etc., has a stable antistatic value, and does not significantly increase the viscosity after aging at high temperature. However, the balance between low-speed peeling force and high-speed peeling force and the influence of high temperature on high-speed peeling force are not verified and explained. Summary of the invention

[0008] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a high temperature resistant antistatic protective film for polarizer and a preparation method thereof. Thus, a high temperature resistant antistatic protective film for polarizer and a preparation method thereof are provided, which has the advantages of high temperature resistance, low scratch resistance, good antistatic properties, etc.

[0009] The content of the present invention is: a high temperature resistant antistatic protective film for polarizer, characterized in that: the high temperature resistant antistatic protective film for polarizer is composed of a composite of overlapping PET substrate film, acrylic pressure-sensitive adhesive layer and release film (i.e. a composite three-layer structure);

[0010] The acrylic pressure-sensitive adhesive layer is formed by curing the acrylic pressure-sensitive adhesive by heating; the acrylic pressure-sensitive adhesive is composed of 90 to 100 parts by weight of a high-temperature resistant acrylic ester polymer, 1.5 to 2 parts by weight of a curing agent, 1 to 1.5 parts by weight of an antistatic agent, 0.5 to 1 parts by weight of a leveling agent, and 20 to 40 parts by weight of a solvent;

[0011] The high temperature resistant acrylate polymer is obtained by free radical polymerization in a solvent of acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat resistant monomer (or heat resistant monomer), cage type polysilsesquioxane and initiator;

[0012] The curing agent is an isocyanate curing agent, preferably one or a mixture of two of toluene diisocyanate, 1,4-tetramethylxylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate;

[0013] The antistatic agent is an ionic antistatic agent, preferably one or a mixture of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide;

[0014] The leveling agent is a hydroxyl-containing leveling agent;

[0015] The solvent is one or a mixture of two or more of ethyl acetate, butanone, cyclohexanone, toluene, methyl isobutyl ketone and butyl acetate.

[0016] In the present invention, the preferred model (brand) of the leveling agent is any one of BYK-370, BYK-SILCLEAN 3700 or BYK-394 produced by BYK Chemical Co., Ltd. of Germany.

[0017] In the present invention, the PET substrate film is the abbreviation of polyethylene terephthalate film layer, and the thickness of the PET film can be 38 to 75 microns. The PET film can be made by Sichuan Dongcai Technology Group Co., Ltd. or a commercial product. A 38 μm thick PET optical substrate film after antistatic treatment is preferred.

[0018] In the content of the present invention: the release film is a transparent polyester film coated with a layer of silicone release agent on the surface, which is a common polyester release film product on the market with a thickness of 25 to 50 μm; D262-L1, D262-SL2, etc. produced by Sichuan Dongcai Technology Group Co., Ltd. can be used.

[0019] In the content of the present invention: the high temperature resistant acrylate polymer is prepared by free radical polymerization of 36-48 parts by weight of acrylate soft monomer, 7-15 parts by weight of acrylate hard monomer, 5-10 parts by weight of acrylate functional monomer, 10-20 parts by weight of heat resistant monomer (or heat resistant monomer), 5-15 parts by weight of cage-type polysilsesquioxane and 0.3-0.5 parts by weight of initiator in 80-100 parts by weight of solvent;

[0020] The acrylic acid ester soft monomer is one or a mixture of two or more of 2-ethylhexyl acrylate, octadecyl acrylate, isooctyl acrylate, n-butyl acrylate, isobutyl acrylate and ethyl acrylate;

[0021] The acrylic acid ester hard monomer is one or a mixture of two or more of methyl acrylate, methyl methacrylate, acrylonitrile, isobutyl methacrylate, tert-butyl methacrylate, and vinyl acetate;

[0022] The acrylate functional monomer is one or a mixture of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, cyclohexyl methacrylate, 1,6-hexanediol diacrylate, 2-methoxyethyl acrylate, 3-ethoxyethyl acrylate, and 2-phenoxyethyl acrylate;

[0023] The heat-resistant monomer is one or a mixture of two or more of maleimide, N-vinyl pyrrolidone, N-hydroxymethyl acrylamide, and N-vinyl carbazole;

[0024] The cage-type polysilsesquioxane has an allyl functional group in its molecular structure, and is preferably one or a mixture of two or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacrylic cage-type polysilsesquioxane, acryl cage-type polysilsesquioxane or octavinyl cage-type polysilsesquioxane;

[0025] The initiator can make the soft monomer, hard monomer, functional monomer, heat-resistant monomer and cage polysilsesquioxane copolymerize. The specific type of the initiator is not limited, and the initiator conventionally used in the art can be selected, for example: azo initiators such as azobisbutyronitrile or peroxide initiators such as benzoyl peroxide.

[0026] In the context of the present invention: the preparation method of the high temperature resistant acrylate polymer is:

[0027] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are fully and evenly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 60-65° C., cage-type polysilsesquioxane and one third of the initiator solution are added, and the mixture is kept warm for reaction for 1 h to 1.5 h to obtain a reaction solution;

[0028] Add the remaining half of the mixed liquid to the reaction liquid, stir thoroughly and heat to 80-85°C, slowly dropwise add the remaining two-thirds of the initiator, react for 3h-3.5h, cool and pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer with a solid content of 25.5%.

[0029] The definition of "solid content" described in this article is: the mass percentage of the remaining solid matter after the acrylate polymer is dried to constant weight at a temperature of 120°C to the total mass of the acrylate polymer; the acrylate polymer with a solid content of 25.5% means that after the acrylate polymer is dried to constant weight at a temperature of 120°C, the mass of the solid matter obtained is 25.5% of the acrylate polymer.

[0030] Another aspect of the present invention is: a method for preparing a high temperature resistant antistatic protective film for a polarizer, characterized in that the steps are:

[0031] a. Preparation of high temperature resistant acrylic polymer:

[0032] Ingredients: Take the raw materials of each component according to the proportion of 36-48 parts by weight of acrylate soft monomer, 7-15 parts by weight of acrylate hard monomer, 5-10 parts by weight of acrylate functional monomer, 10-20 parts by weight of heat-resistant monomer (or heat-resistant monomer), 10-15 parts by weight of cage-type polysilsesquioxane, 0.3-0.5 parts by weight of initiator and 80-100 parts by weight of solvent, and set aside;

[0033] Fully and uniformly mix the acrylic soft monomer, the acrylic hard monomer, the acrylic functional monomer, the heat-resistant monomer and the solvent to obtain a mixed solution, add one-half of the mixed solution into a reaction container, add cage-type polysilsesquioxane and one-third of the initiator solution when heated to 60-65° C., and keep the mixture warm for 1 h to 1.5 h to obtain a reaction solution;

[0034] Add the remaining half of the mixed liquid to the reaction liquid, stir thoroughly and heat to 80-85°C, slowly dropwise add the remaining two-thirds of the initiator, react for 3h-3.5h, cool and pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer with a solid content of 25.5%.

[0035] The acrylic acid ester soft monomer is one or a mixture of two or more of 2-ethylhexyl acrylate, octadecyl acrylate, isooctyl acrylate, n-butyl acrylate, isobutyl acrylate and ethyl acrylate;

[0036] The acrylic acid ester hard monomer is one or a mixture of two or more of methyl acrylate, methyl methacrylate, acrylonitrile, isobutyl methacrylate, tert-butyl methacrylate, and vinyl acetate;

[0037] The acrylate functional monomer is one or a mixture of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, cyclohexyl methacrylate, 1,6-hexanediol diacrylate, 2-methoxyethyl acrylate, 3-ethoxyethyl acrylate, and 2-phenoxyethyl acrylate;

[0038] The heat-resistant monomer is one or a mixture of two or more of maleimide, N-vinyl pyrrolidone, N-hydroxymethyl acrylamide, and N-vinyl carbazole;

[0039] The cage-type polysilsesquioxane has an allyl functional group in its molecular structure, and is preferably one or a mixture of two or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacrylic cage-type polysilsesquioxane, acryl cage-type polysilsesquioxane or octavinyl cage-type polysilsesquioxane;

[0040] The initiator can make the above-mentioned soft monomer, hard monomer, functional monomer, heat-resistant monomer and cage-type polysilsesquioxane copolymerize. The specific type of the initiator is not limited, and the initiator conventionally used in the art can be selected, for example: the initiator can make the above-mentioned soft monomer, hard monomer, functional monomer, heat-resistant monomer and cage-type polysilsesquioxane copolymerize. The specific type of the initiator is not limited, and the initiator conventionally used in the art can be selected, for example: azo-based polymerization initiators such as azobisbutyronitrile or peroxide-based initiators such as benzoyl peroxide.

[0041] b. Preparation of acrylic pressure-sensitive adhesive:

[0042] Ingredients: 90-100 parts by weight of the high temperature resistant acrylate polymer prepared in step a, 1.5-2 parts by weight of a curing agent, 1-1.5 parts by weight of an antistatic agent, 0.5-1 parts by weight of a leveling agent, and 20-40 parts by weight of a solvent are prepared and set aside;

[0043] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and fully stirred at a speed of 300 to 700 rpm for 10 to 15 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 300 to 700 rpm for 5 to 10 minutes until it is uniform, thereby obtaining an acrylic pressure-sensitive adhesive;

[0044] The curing agent is an isocyanate curing agent, preferably one or a mixture of two of toluene diisocyanate, 1,4-tetramethylxylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate;

[0045] The antistatic agent is an ionic antistatic agent, preferably one or a mixture of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide;

[0046] The leveling agent is a hydroxyl-containing leveling agent;

[0047] The solvent is one or a mixture of two or more of ethyl acetate, butanone, cyclohexanone, toluene, methyl isobutyl ketone and butyl acetate.

[0048] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0049] The acrylic pressure-sensitive adhesive (prepared in step b) is coated on the PET substrate film by a coating machine, and cured at a temperature of 120-125° C. for 1-1.5 min to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 60-65° C. for two days to obtain a high-temperature resistant antistatic protective film for polarizer (or high-temperature resistant antistatic surface protective film for polarizer).

[0050] In the present invention, the preferred model (brand) of the leveling agent is any one of BYK-370, BYK-SILCLEAN 3700 or BYK-394 produced by BYK Chemical Co., Ltd. of Germany.

[0051] In the content of the present invention: the PET substrate film is the abbreviation of polyethylene terephthalate film layer, and the thickness of the PET substrate film can be 38 to 75 μm; the PET substrate film can be made by Sichuan Dongcai Technology Group Co., Ltd., or a commercially available product can be used; the better one is a 38 μm thick PET optical substrate film after antistatic treatment.

[0052] In the content of the present invention: the release film is a transparent polyester film coated with a layer of silicone release agent on the surface, which is a common polyester release film product on the market with a thickness of 25 to 50 μm. D262-L1, D262-SL2, etc. produced by Sichuan Dongcai Technology Group Co., Ltd. can be used.

[0053] In another aspect of the present invention: the acrylic pressure-sensitive adhesive layer (or dry adhesive) in step c preferably has a thickness of 15 to 20 μm.

[0054] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0055] (1) The present invention uses an acrylate monomer and a cage-type polysilsesquioxane with an allyl functional group to carry out a polymerization reaction, and the monomer group provides a cross-linking site to form a network structure of the polymer, thereby improving the overall cross-linking density of the acrylic pressure-sensitive adhesive, thereby improving the overall strength and modulus of the adhesive layer in the surface protective film; after being placed in a high-temperature environment of 85°C, the high-temperature resistant antistatic protective film prepared by the present invention can still maintain viscosity, and the adhesive layer structure will not be destroyed. After returning to room temperature, the peeling force climbs little and is still relatively easy to peel off, and has the advantages of high temperature resistance, low climb, good scratch resistance and antistatic properties;

[0056] (2) In the acrylic pressure-sensitive adhesive of the high-temperature resistant antistatic protective film for the polarizer of the present invention, the antistatic agent has good compatibility with the acrylate polymer, the antistatic agent does not precipitate in the acrylic pressure-sensitive adhesive layer, the surface resistance of the acrylic pressure-sensitive adhesive layer is below 10^10Ω, and has an antistatic effect;

[0057] (3) The low-speed (300 mm / min) peeling force of the high-temperature resistant antistatic protective film (prepared) of the present invention is ≤10 gf / 25 mm, and the high-speed (30000 mm / min) peeling force is ≤80 gf / 25 mm, and the peeling force is within the required range of the polarizer surface protective film; the product preparation process is simple, easy to operate, has good performance, and is highly practical. DETAILED DESCRIPTION

[0058] The following embodiments are intended to further illustrate the present invention, but should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by technicians in this field based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0059] In the following examples, the specific units of parts by weight are all grams (g).

[0060] Embodiment 1:

[0061] A method for preparing a high temperature resistant antistatic protective film for a polarizer, comprising the following steps:

[0062] a. Preparation of high temperature resistant acrylic polymer:

[0063] Ingredients: 40 parts by weight of acrylate soft monomer (including 14 parts of 2-ethylhexyl acrylate, 10 parts of n-butyl acrylate, and 16 parts of isooctyl acrylate), 12 parts by weight of acrylate hard monomer (including 6 parts of methyl acrylate and 6 parts of isobutyl methacrylate), 5 parts by weight of acrylate functional monomer (cyclohexyl methacrylate), 16 parts by weight of heat-resistant monomer (including 7 parts of maleimide and 9 parts of N-vinyl carbazole), 13 parts by weight of cage-type polysilsesquioxane (methacrylic cage-type polysilsesquioxane), 0.3 parts by weight of initiator (azobisbutyronitrile), and 95 parts by weight of solvent (ethyl acetate) are taken and set aside;

[0064] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and 45 parts by weight of ethyl acetate solvent are fully and evenly mixed to obtain a mixed solution, and one-half of the mixed solution is added to a reaction container, and when heated to 60° C., cage-type polysilsesquioxane and 0.1 parts by weight of an initiator solution are added, and the mixture is kept warm for 1 hour to obtain a reaction solution;

[0065] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 80°C, slowly dropwise add the remaining 0.2 parts by weight of the initiator, react for 3 hours, cool and pour out, add the remaining solvent ethyl acetate to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0066] b. Preparation of acrylic pressure-sensitive adhesive:

[0067] Ingredients: 100 parts by weight of the high temperature resistant acrylic polymer prepared in step a, 1.5 parts by weight of a curing agent (hexamethylene diisocyanate), 1.5 parts by weight of an antistatic agent (1-ethyl-3-methylimidazole bistrifluoromethanesulfonyl imide salt), 0.5 parts by weight of a leveling agent (BKY-394), and 20 parts by weight of a solvent (ethyl acetate) are taken and set aside;

[0068] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and fully stirred at a speed of 500 rpm for 13 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 500 rpm for 8 minutes until it is uniform, thereby obtaining an acrylic pressure-sensitive adhesive;

[0069] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0070] The acrylic pressure-sensitive adhesive prepared in step b is coated on the PET substrate film by a coating machine, and cured at a temperature of 120° C. for 1 minute to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 60° C. for two days to obtain a high-temperature resistant antistatic protective film for polarizer (or a high-temperature resistant antistatic surface protective film for polarizer);

[0071] The PET substrate film in step c is a commercially available PET optical substrate film with a thickness of 38 μm and after antistatic treatment;

[0072] The release film in step c is a transparent polyester film coated with a layer of silicone release agent on the surface, which is a commercially available common polyester release film product.

[0073] The acrylic pressure-sensitive adhesive layer (or dry adhesive) in step c has a thickness of 15 μm.

[0074] Embodiment 2:

[0075] A method for preparing a high temperature resistant antistatic protective film for a polarizer, comprising the following steps:

[0076] a. Preparation of high temperature resistant acrylic polymer:

[0077] Ingredients: 37 parts by weight of acrylate soft monomer (including 10 parts of 2-ethylhexyl acrylate, 12 parts of n-butyl acrylate, and 15 parts of isooctyl acrylate), 12 parts by weight of acrylate hard monomer (including 6 parts of methyl methacrylate and 6 parts of isobutyl methacrylate), 5 parts by weight of acrylate functional monomer (cyclohexyl methacrylate), 16 parts by weight of heat-resistant monomer (including 7 parts of maleimide and 9 parts of N-vinyl carbazole), 15 parts by weight of cage-type polysilsesquioxane (methacryloxypropyl cage-type polysilsesquioxane), 0.3 parts by weight of initiator (azobisbutyronitrile), and 95 parts by weight of solvent (ethyl acetate) are taken and set aside;

[0078] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and 45 parts by weight of ethyl acetate solvent are fully and evenly mixed to obtain a mixed solution, and one-half of the mixed solution is added to a reaction container, and when heated to 60° C., cage-type polysilsesquioxane and 0.1 parts by weight of an initiator solution are added, and the mixture is kept warm for 1 hour to obtain a reaction solution;

[0079] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 80°C, slowly dropwise add the remaining 0.2 parts by weight of the initiator, react for 3 hours, cool and pour out, add the remaining solvent ethyl acetate to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0080] b. Preparation of acrylic pressure-sensitive adhesive:

[0081] Ingredients: 100 parts by weight of the high temperature resistant acrylic polymer prepared in step a, 1.5 parts by weight of a curing agent (hexamethylene diisocyanate), 1.5 parts by weight of an antistatic agent (1-ethyl-3-methylimidazole bistrifluoromethanesulfonyl imide salt), 0.5 parts by weight of a leveling agent (BKY-394), and 20 parts by weight of a solvent (ethyl acetate) are taken and set aside;

[0082] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and fully stirred at a speed of 500 rpm for 13 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 500 rpm for 8 minutes until it is uniform, thereby obtaining an acrylic pressure-sensitive adhesive;

[0083] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0084] The acrylic pressure-sensitive adhesive prepared in step b is coated on the PET substrate film by a coating machine, and cured at a temperature of 120° C. for 1 minute to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 60° C. for two days to obtain a high-temperature resistant antistatic protective film for polarizer (or a high-temperature resistant antistatic surface protective film for polarizer);

[0085] The PET substrate film in step c is a commercially available PET optical substrate film with a thickness of 38 μm and after antistatic treatment;

[0086] The release film in step c is: a transparent polyester film coated with a layer of silicone release agent on the surface, which is a common polyester release film product available on the market;

[0087] The acrylic pressure-sensitive adhesive layer (or dry adhesive) in step c has a thickness of 15 μm.

[0088] Embodiment 3:

[0089] A method for preparing a high temperature resistant antistatic protective film for a polarizer, comprising the following steps:

[0090] a. Preparation of high temperature resistant acrylic polymer:

[0091] Ingredients: 37 parts by weight of acrylate soft monomer (including 10 parts of 2-ethylhexyl acrylate, 12 parts of n-butyl acrylate, and 15 parts of isooctyl acrylate), 12 parts by weight of acrylate hard monomer (including 6 parts of methyl acrylate and 6 parts of isobutyl methacrylate), 5 parts by weight of acrylate functional monomer (cyclohexyl methacrylate), 16 parts by weight of heat-resistant monomer (including 7 parts of maleimide and 9 parts of N-vinyl carbazole), 17 parts by weight of cage-type polysilsesquioxane (methacryloxypropyl cage-type polysilsesquioxane), 0.3 parts by weight of initiator (azobisbutyronitrile), and 95 parts by weight of solvent (ethyl acetate) are taken and set aside;

[0092] The acrylic soft monomer, the acrylic hard monomer, the acrylic functional monomer, the heat-resistant monomer and 45 parts by weight of the solvent ethyl acetate are fully and evenly mixed to obtain a mixed solution, and one-half of the mixed solution is added to a reaction container, and when heated to 60° C., cage-type polysilsesquioxane and 0.1 parts by weight of an initiator (solution) are added, and the mixture is kept warm for 1 hour to obtain a reaction solution;

[0093] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 80°C, add (slowly dropwise) the remaining 0.2 parts by weight of the initiator, react for 3 hours, cool and pour out, add the remaining solvent ethyl acetate to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0094] b. Preparation of acrylic pressure-sensitive adhesive:

[0095] Ingredients: 100 parts by weight of the high temperature resistant acrylate polymer prepared in step a, 1.5 parts by weight of a curing agent (hexamethylene diisocyanate), 1.5 parts by weight of an antistatic agent (1-ethyl-3-methylimidazole bistrifluoromethanesulfonyl imide salt), 0.5 parts by weight of a leveling agent (BYK-394), and 20 parts by weight of a solvent (ethyl acetate) are taken and set aside;

[0096] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and fully stirred at a speed of 500 rpm for 13 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 500 rpm for 8 minutes until it is uniform, thereby obtaining an acrylic pressure-sensitive adhesive;

[0097] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0098] The acrylic pressure-sensitive adhesive prepared in step b is coated on the PET substrate film by a coating machine, and cured at a temperature of 120° C. for 1 minute to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 60° C. for two days to obtain a high-temperature resistant antistatic protective film for polarizer (or a high-temperature resistant antistatic surface protective film for polarizer);

[0099] The PET substrate film in step c is a commercially available PET optical substrate film with a thickness of 38 μm and after antistatic treatment;

[0100] The release film in step c is: a transparent polyester film coated with a layer of silicone release agent on the surface, which is a common polyester release film product available on the market;

[0101] The acrylic pressure-sensitive adhesive layer (or dry adhesive) in step c has a thickness of 15 μm.

[0102] Embodiment 4:

[0103] A method for preparing a high temperature resistant antistatic protective film for a polarizer, comprising the following steps:

[0104] a. Preparation of high temperature resistant acrylic polymer:

[0105] Ingredients: 37 parts by weight of acrylate soft monomer (including 10 parts of 2-ethylhexyl acrylate, 12 parts of n-butyl acrylate, and 15 parts of isooctyl acrylate), 12 parts by weight of acrylate hard monomer (including 6 parts of methyl acrylate and 6 parts of isobutyl methacrylate), 7 parts by weight of acrylate functional monomer (including 3 parts of cyclohexyl methacrylate and 4 parts of 1,6-hexanediol diacrylate), 12 parts by weight of heat-resistant monomer (N-hydroxymethyl acrylamide), 8 parts by weight of cage-type polysilsesquioxane (octavinyl cage-type polysilsesquioxane), 0.3 parts by weight of initiator (azobisbutyronitrile), and 95 parts by weight of solvent (ethyl acetate) are taken and set aside;

[0106] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and 45 parts by weight of ethyl acetate solvent are fully and evenly mixed to obtain a mixed solution, and one-half of the mixed solution is added to a reaction container, and when heated to 60° C., cage-type polysilsesquioxane and 0.1 parts by weight of an initiator solution are added, and the mixture is kept warm for 1 hour to obtain a reaction solution;

[0107] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 80°C, slowly dropwise add the remaining 0.2 parts by weight of the initiator, react for 3 hours, cool and pour out, add the remaining solvent ethyl acetate to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0108] b. Preparation of acrylic pressure-sensitive adhesive:

[0109] Ingredients: 100 parts by weight of the high temperature resistant acrylate polymer prepared in step a, 1.5 parts by weight of a curing agent (hexamethylene diisocyanate), 1.5 parts by weight of an antistatic agent (1-ethyl-3-methylimidazole bistrifluoromethanesulfonyl imide salt), 0.5 parts by weight of a leveling agent (BYK-394), and 20 parts by weight of a solvent (ethyl acetate) are taken and set aside;

[0110] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and fully stirred at a speed of 500 rpm for 13 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 500 rpm for 8 minutes until it is uniform, thereby obtaining an acrylic pressure-sensitive adhesive;

[0111] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0112] The acrylic pressure-sensitive adhesive prepared in step b is coated on the PET substrate film by a coating machine, and cured at a temperature of 120° C. for 1 minute to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 60° C. for two days to obtain a high-temperature resistant antistatic protective film for polarizer (or a high-temperature resistant antistatic surface protective film for polarizer);

[0113] The PET substrate film in step c is a commercially available PET optical substrate film with a thickness of 38 μm and after antistatic treatment;

[0114] The release film in step c is: a transparent polyester film coated with a layer of silicone release agent on the surface, which is a common polyester release film product available on the market;

[0115] The acrylic pressure-sensitive adhesive layer (or dry adhesive) in step c has a thickness of 15 μm.

[0116] Comparative Example 1:

[0117] The difference between Comparative Example 1 and Example 1 is that the methacrylic acid-based cage-type polysilsesquioxane is replaced by an equal weight portion of trimethylsilyl-based cage-type polysilsesquioxane.

[0118] Comparative Example 2:

[0119] The difference between Comparative Example 2 and Example 1 is that the methacrylic cage-type polysilsesquioxane is replaced by an equal weight portion of methacryloxypropylsiloxane.

[0120] Comparative Example 3:

[0121] The only difference between Comparative Example 3 and Example 1 is that no heat-resistant monomers maleimide and N-vinyl carbazole are added to the raw materials for preparing the high-temperature-resistant acrylate polymer.

[0122] The performance tests were conducted on the surface protection films prepared in Examples 1 to 4 and Comparative Examples 1 to 3, respectively, and the test results shown in Table 1 below were obtained.

[0123] The performance test methods in the table are as follows:

[0124] (1) 180° peel strength test: Peel strength was measured in accordance with the national standard GB / T 2792-2014. The prepared protective film (90×25 mm) was pasted on a mirror steel plate, and rolled back and forth once with a 2 kg roller. After being placed at room temperature for 20 minutes, the peel strength was measured with a tensile tester at test speeds of 300 mm / min and 3000 mm / min.

[0125] (2) High temperature peeling force test: The prepared protective film (90×25 mm) was pasted on a mirror steel plate, rolled back and forth once with a 2 kg roller, placed in a 100°C oven for 2 h, taken out and cooled for 1 h, and the peeling force was measured by a tensile tester. The test speeds were 300 mm / min and 30,000 mm / min.

[0126] (3) Adhesive layer resistance test: Cut the protective film into A4 size, remove the release film, and test the adhesive surface resistance on a high resistance meter.

[0127] (4) Aging test: The protective film is subjected to an aging test under the test conditions of 85°C*85%RH*72Hr. After the sample has been aged for 72 hours, it is left at room temperature for 2 hours to observe whether there are any abnormal phenomena such as bubbling, floating, or white fog on the surface. The protective film is then torn off and a strong flashlight is used to observe whether there is any residual glue or shadow on the surface of the object being adhered.

[0128] Table 1: Performance data table:

[0129]

[0130] Note: ○ represents no abnormal phenomenon, △ represents any abnormal phenomenon, and × represents multiple abnormal phenomena.

[0131] From the comparison of the test results of Examples 1-4 and Comparative Example 2 in Table 1, it can be seen that adding cage-type polysilsesquioxane with double bond groups to the acrylic pressure-sensitive adhesive can improve the high temperature resistance of the protective film, and the peeling force rises slowly after high temperature.

[0132] Compared with Example 1, it can be seen that if the amount of cage-type polysilsesquioxane added is too large (Example 3), although the high temperature resistance is increased, it is easy to precipitate after aging, resulting in abnormal phenomena such as dark shadows on the adhered object. If the amount of cage-type polysilsesquioxane added is too small (Example 4), the peel force increases and the high temperature resistance effect is weakened.

[0133] According to the performance results of Comparative Example 1, the cage-type polysilsesquioxane added in Comparative Example 1 does not contain a double bond group and cannot participate in the polymerization reaction to form a network structure, so the peeling force increases significantly after high temperature.

[0134] Embodiment 5:

[0135] A high temperature resistant antistatic protective film for a polarizer, the high temperature resistant antistatic protective film for a polarizer is composed of a PET substrate film, an acrylic pressure-sensitive adhesive layer and a release film which are overlapped in sequence;

[0136] The acrylic pressure-sensitive adhesive layer is formed by curing the acrylic pressure-sensitive adhesive by heating; the acrylic pressure-sensitive adhesive is composed of 90 parts by weight of a high-temperature resistant acrylic ester polymer, 1.5 parts by weight of a curing agent, 1 part by weight of an antistatic agent, 0.5 parts by weight of a leveling agent, and 20 parts by weight of a solvent;

[0137] The high temperature resistant acrylate polymer is obtained by free radical polymerization of acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat resistant monomer, cage type polysilsesquioxane and initiator in a solvent.

[0138] Embodiment 6:

[0139] A high temperature resistant antistatic protective film for a polarizer, the high temperature resistant antistatic protective film for a polarizer is composed of a PET substrate film, an acrylic pressure-sensitive adhesive layer and a release film which are overlapped in sequence;

[0140] The acrylic pressure-sensitive adhesive layer is formed by curing the acrylic pressure-sensitive adhesive by heating; the acrylic pressure-sensitive adhesive is composed of 100 parts by weight of a high-temperature resistant acrylic ester polymer, 2 parts by weight of a curing agent, 1.5 parts by weight of an antistatic agent, 1 part by weight of a leveling agent, and 40 parts by weight of a solvent;

[0141] The high temperature resistant acrylate polymer is obtained by free radical polymerization of acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat resistant monomer, cage type polysilsesquioxane and initiator in a solvent.

[0142] Embodiment 7:

[0143] A high temperature resistant antistatic protective film for a polarizer, the high temperature resistant antistatic protective film for a polarizer is composed of a PET substrate film, an acrylic pressure-sensitive adhesive layer and a release film which are overlapped in sequence;

[0144] The acrylic pressure-sensitive adhesive layer is formed by curing an acrylic pressure-sensitive adhesive by heating; the acrylic pressure-sensitive adhesive is composed of 95 parts by weight of a high-temperature resistant acrylic ester polymer, 1.8 parts by weight of a curing agent, 1.3 parts by weight of an antistatic agent, 0.8 parts by weight of a leveling agent, and 30 parts by weight of a solvent;

[0145] The high temperature resistant acrylate polymer is obtained by free radical polymerization of acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat resistant monomer, cage type polysilsesquioxane and initiator in a solvent.

[0146] In the above-mentioned embodiments 5-7:

[0147] The curing agent is an isocyanate curing agent, preferably one or a mixture of two of toluene diisocyanate, 1,4-tetramethylxylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate;

[0148] The antistatic agent is an ionic antistatic agent, preferably one or a mixture of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide;

[0149] The leveling agent is a hydroxyl-containing leveling agent, and the preferred model (brand) is any one of BYK-370, BYK-SILCLEAN 3700 or BYK-394 produced by BYK Chemical Co., Ltd. of Germany.

[0150] The solvent is one or a mixture of two or more of ethyl acetate, butanone, cyclohexanone, toluene, methyl isobutyl ketone, and butyl acetate;

[0151] The PET substrate film is the abbreviation of polyethylene terephthalate film layer, and the thickness of the PET film can be 38 to 75 μm. The PET film uses commercially available products. The preferred one is a 38 μm thick PET optical substrate film after antistatic treatment.

[0152] The release film is a transparent polyester film with a layer of silicon-based release agent coated on the surface, and is a common polyester release film product available on the market.

[0153] Embodiment 8:

[0154] A high temperature resistant antistatic protective film for a polarizer, wherein the high temperature resistant acrylate polymer is prepared by free radical polymerization of 36 parts by weight of acrylate soft monomer, 7 parts by weight of acrylate hard monomer, 5 parts by weight of acrylate functional monomer, 10 parts by weight of heat resistant monomer (or heat resistant monomer), 5 parts by weight of cage-type polysilsesquioxane and 0.3 parts by weight of initiator in 80 parts by weight of solvent;

[0155] The preparation method of the high temperature resistant acrylate polymer is:

[0156] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are fully and evenly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 60° C., cage-type polysilsesquioxane and one third of an initiator (solution) are added, and the mixture is kept warm for 1 hour to obtain a reaction solution;

[0157] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 80°C, add the remaining two-thirds of the initiator (slowly dropwise), react for 3 hours, cool and pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0158] The rest are the same as any one of Examples 5-7 and are omitted.

[0159] Embodiment 9:

[0160] A high temperature resistant antistatic protective film for a polarizer, wherein the high temperature resistant acrylate polymer is prepared by free radical polymerization of 48 parts by weight of acrylate soft monomer, 15 parts by weight of acrylate hard monomer, 10 parts by weight of acrylate functional monomer, 20 parts by weight of heat resistant monomer, 15 parts by weight of cage-type polysilsesquioxane and 0.5 parts by weight of initiator in 100 parts by weight of solvent;

[0161] The preparation method of the high temperature resistant acrylate polymer is:

[0162] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are fully and evenly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 65° C., cage-type polysilsesquioxane and one third of an initiator (solution) are added, and the mixture is kept warm for reaction for 1.5 hours to obtain a reaction solution;

[0163] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 85°C, add the remaining two-thirds of the initiator (slowly dropwise), react for 3.5 hours, cool and pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0164] The rest are the same as any one of Examples 5-7 and are omitted.

[0165] Embodiment 10:

[0166] A high temperature resistant antistatic protective film for a polarizer, wherein the high temperature resistant acrylate polymer is prepared by free radical polymerization in 90 parts by weight of a solvent by 42 parts by weight of an acrylate soft monomer, 11 parts by weight of an acrylate hard monomer, 8 parts by weight of an acrylate functional monomer, 15 parts by weight of a heat resistant monomer, 10 parts by weight of a cage-type polysilsesquioxane and 0.4 parts by weight of an initiator;

[0167] The preparation method of the high temperature resistant acrylate polymer is:

[0168] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are fully and evenly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 62° C., cage-type polysilsesquioxane and one third of an initiator (solution) are added, and the mixture is kept warm for reaction for 1.2 hours to obtain a reaction solution;

[0169] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 82°C, add the remaining two-thirds of the initiator (slowly dropwise), react for 3.2 hours, pour out (cool down), add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0170] The rest are the same as any one of Examples 5-7 and are omitted.

[0171] In the above-mentioned embodiments 8-10:

[0172] The acrylic acid ester soft monomer is one or a mixture of two or more of 2-ethylhexyl acrylate, octadecyl acrylate, isooctyl acrylate, n-butyl acrylate, isobutyl acrylate and ethyl acrylate;

[0173] The acrylic acid ester hard monomer is one or a mixture of two or more of methyl acrylate, methyl methacrylate, acrylonitrile, isobutyl methacrylate, tert-butyl methacrylate, and vinyl acetate;

[0174] The acrylate functional monomer is one or a mixture of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, cyclohexyl methacrylate, 1,6-hexanediol diacrylate, 2-methoxyethyl acrylate, 3-ethoxyethyl acrylate, and 2-phenoxyethyl acrylate;

[0175] The heat-resistant monomer is one or a mixture of two or more of maleimide, N-vinyl pyrrolidone, N-hydroxymethyl acrylamide, and N-vinyl carbazole;

[0176] The cage-type polysilsesquioxane has an allyl functional group in its molecular structure, and is preferably one or a mixture of two or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacrylic cage-type polysilsesquioxane, acryl cage-type polysilsesquioxane or octavinyl cage-type polysilsesquioxane;

[0177] The initiator can make the soft monomer, hard monomer, functional monomer, heat-resistant monomer and cage-type polysilsesquioxane copolymerize. The specific type of the initiator is not limited, and the initiator conventionally used in the art can be selected, such as azobisbutyronitrile, for example, azo-based polymerization initiators such as azobisbutyronitrile or peroxide-based initiators such as benzoyl peroxide.

[0178] Embodiment 11:

[0179] A method for preparing a high temperature resistant antistatic protective film for a polarizer, comprising the following steps:

[0180] a. Preparation of high temperature resistant acrylic polymer:

[0181] Ingredients: Take the raw materials of each component according to the ratio of 36 parts by weight of acrylate soft monomer, 7 parts by weight of acrylate hard monomer, 5 parts by weight of acrylate functional monomer, 10 parts by weight of heat-resistant monomer, 5 parts by weight of cage-type polysilsesquioxane, 0.3 parts by weight of initiator and 80 parts by weight of solvent, and set aside;

[0182] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are fully and evenly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 60° C., cage-type polysilsesquioxane and one third of an initiator (solution) are added, and the mixture is kept warm for 1 hour to obtain a reaction solution;

[0183] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 80°C, add the remaining two-thirds of the initiator (slowly dropwise), react for 3 hours, cool and pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0184] b. Preparation of acrylic pressure-sensitive adhesive:

[0185] Ingredients: 90 parts by weight of the high temperature resistant acrylate polymer prepared in step a, 1.5 parts by weight of a curing agent, 1 part by weight of an antistatic agent, 0.5 parts by weight of a leveling agent, and 20 parts by weight of a solvent are prepared and set aside;

[0186] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and fully stirred at a speed of 300 rpm for 15 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 300 rpm for 10 minutes until uniform, thereby obtaining an acrylic pressure-sensitive adhesive;

[0187] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0188] The acrylic pressure-sensitive adhesive prepared in step b is coated on the PET substrate film by a coating machine, and cured at a temperature of 120° C. for 1 minute to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 60° C. for two days to obtain a high-temperature resistant antistatic protective film for a polarizer.

[0189] Embodiment 12:

[0190] A method for preparing a high temperature resistant antistatic protective film for a polarizer, comprising the following steps:

[0191] a. Preparation of high temperature resistant acrylic polymer:

[0192] Ingredients: Take the raw materials of each component according to the ratio of 42 parts by weight of acrylate soft monomer, 11 parts by weight of acrylate hard monomer, 7 parts by weight of acrylate functional monomer, 15 parts by weight of heat-resistant monomer, 10 parts by weight of cage-type polysilsesquioxane, 0.4 parts by weight of initiator and 90 parts by weight of solvent, and set aside;

[0193] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are fully and evenly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 60° C., cage-type polysilsesquioxane and one third of an initiator (solution) are added, and the mixture is kept warm for 1 hour to obtain a reaction solution;

[0194] Add the remaining half of the mixed solution to the reaction solution, stir thoroughly and heat to 80°C, add the remaining two-thirds of the initiator (slowly dropwise), react for 3 hours, cool and pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0195] b. Preparation of acrylic pressure-sensitive adhesive:

[0196] Ingredients: 95 parts by weight of the high temperature resistant acrylate polymer prepared in step a, 1.7 parts by weight of a curing agent, 1.2 parts by weight of an antistatic agent, 0.7 parts by weight of a leveling agent, and 30 parts by weight of a solvent are prepared and set aside;

[0197] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and stirred (fully) at a speed of 500 rpm for 13 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 500 rpm for 8 minutes until it is uniform, thereby obtaining an acrylic pressure-sensitive adhesive;

[0198] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0199] The acrylic pressure-sensitive adhesive prepared in step b is coated on the PET substrate film by a coating machine, and cured at a temperature of 120° C. for 1 minute to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 60° C. for two days to obtain a high-temperature resistant antistatic protective film for a polarizer.

[0200] Embodiment 13:

[0201] A method for preparing a high temperature resistant antistatic protective film for a polarizer, comprising the following steps:

[0202] a. Preparation of high temperature resistant acrylic polymer:

[0203] Ingredients: Take the raw materials of each component according to the ratio of 48 parts by weight of acrylate soft monomer, 15 parts by weight of acrylate hard monomer, 10 parts by weight of acrylate functional monomer, 20 parts by weight of heat-resistant monomer, 15 parts by weight of cage-type polysilsesquioxane, 0.5 parts by weight of initiator and 100 parts by weight of solvent, and set aside;

[0204] The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are fully and evenly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 60-65° C., cage-type polysilsesquioxane and one third of an initiator (solution) are added, and the mixture is kept warm for reaction for 1 h to 1.5 h to obtain a reaction solution;

[0205] Add the remaining half of the mixed solution to the reaction solution, stir (fully) and heat to 85°C, add (slowly dropwise) the remaining two-thirds of the initiator, react for 3.5 hours, cool and pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer;

[0206] b. Preparation of acrylic pressure-sensitive adhesive:

[0207] Ingredients: 100 parts by weight of the high temperature resistant acrylate polymer prepared in step a, 2 parts by weight of a curing agent, 1.5 parts by weight of an antistatic agent, 1 part by weight of a leveling agent, and 40 parts by weight of a solvent are prepared and set aside;

[0208] Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and stirred (fully) for 10 minutes at a speed of 700 rpm; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and each time a component raw material is added, it is mixed at a speed of 700 rpm for 5 minutes until it is uniform, to obtain an acrylic pressure-sensitive adhesive;

[0209] c. Preparation of high temperature resistant antistatic protective film for polarizer:

[0210] The acrylic pressure-sensitive adhesive prepared in step b is coated on the PET substrate film by a coating machine, and cured at a temperature of 125° C. for 1.5 minutes to form an acrylic pressure-sensitive adhesive layer (or dry adhesive), and then covered with a release film and aged at a temperature of 65° C. for two days to obtain a high-temperature resistant antistatic protective film for a polarizer.

[0211] In step a of above-mentioned embodiment 11-13:

[0212] The acrylic acid ester soft monomer is one or a mixture of two or more of 2-ethylhexyl acrylate, octadecyl acrylate, isooctyl acrylate, n-butyl acrylate, isobutyl acrylate and ethyl acrylate;

[0213] The acrylic acid ester hard monomer is one or a mixture of two or more of methyl acrylate, methyl methacrylate, acrylonitrile, isobutyl methacrylate, tert-butyl methacrylate, and vinyl acetate;

[0214] The acrylate functional monomer is one or a mixture of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, cyclohexyl methacrylate, 1,6-hexanediol diacrylate, 2-methoxyethyl acrylate, 3-ethoxyethyl acrylate, and 2-phenoxyethyl acrylate;

[0215] The heat-resistant monomer is one or a mixture of two or more of maleimide, N-vinyl pyrrolidone, N-hydroxymethyl acrylamide, and N-vinyl carbazole;

[0216] The cage-type polysilsesquioxane has an allyl functional group in its molecular structure, and is preferably one or a mixture of two or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacrylic cage-type polysilsesquioxane, acryl cage-type polysilsesquioxane or octavinyl cage-type polysilsesquioxane;

[0217] The initiator can make the soft monomer, hard monomer, functional monomer, heat-resistant monomer and cage polysilsesquioxane copolymerize. The specific type of the initiator is not limited, and the initiator conventionally used in the art can be selected, for example: azo polymerization initiators such as azobisbutyronitrile or peroxide initiators such as benzoyl peroxide.

[0218] In step b of above-mentioned embodiment 11-13:

[0219] The curing agent is an isocyanate curing agent, preferably one or a mixture of two of toluene diisocyanate, 1,4-tetramethylxylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate;

[0220] The antistatic agent is an ionic antistatic agent, preferably one or a mixture of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide;

[0221] The leveling agent is a hydroxyl-containing leveling agent, and the preferred model (brand) is any one of BYK-370, BYK-SILCLEAN 3700 or BYK-394 produced by BYK Chemical Co., Ltd. of Germany.

[0222] The solvent is one or a mixture of two or more of ethyl acetate, butanone, cyclohexanone, toluene, methyl isobutyl ketone, and butyl acetate;

[0223] The PET substrate film is the abbreviation of polyethylene terephthalate film layer, and the thickness of the PET substrate film can be 38-75 μm; the PET substrate film can be made by Sichuan Dongcai Technology Group Co., Ltd., or a commercially available product can be used;

[0224] The release film is a transparent polyester film coated with a layer of silicone release agent on the surface. It is a common polyester release film product on the market with a thickness of 25 to 50 μm. D262-L1, D262-SL2, etc. produced by Sichuan Dongcai Technology Group Co., Ltd. can be used.

[0225] The acrylic pressure-sensitive adhesive layer (or dry adhesive) has a thickness ranging from 15 to 20 μm.

[0226] In the above embodiments: the percentages used, unless otherwise specified, are all weight (mass) percentages or percentages known to those skilled in the art; the proportions used, unless otherwise specified, are all weight (mass) proportions; and the weights may be in grams or kilograms.

[0227] In the above embodiments, the process parameters (temperature, time, rotation speed, etc.) in each step and the numerical values ​​of the amounts of each component are ranges, and any point can be applied.

[0228] The technical contents not specifically described in the present invention and the above embodiments are the same as the prior art, and the raw materials are all commercially available products.

[0229] The present invention is not limited to the above embodiments, and all the contents of the present invention can be implemented and have the above good effects.

Claims

1. A high temperature resistant antistatic protective film for polarizer, characterized by: The high temperature resistant antistatic protective film for polarizer is composed of a composite of a PET substrate film, an acrylic pressure-sensitive adhesive layer and a release film which are overlapped in sequence; The acrylic pressure-sensitive adhesive layer is formed by curing the acrylic pressure-sensitive adhesive by heating; the acrylic pressure-sensitive adhesive is composed of 90 to 100 parts by weight of a high-temperature resistant acrylic ester polymer, 1.5 to 2 parts by weight of a curing agent, 1 to 1.5 parts by weight of an antistatic agent, 0.5 to 1 parts by weight of a leveling agent, and 20 to 40 parts by weight of a solvent; The high temperature resistant acrylate polymer is obtained by free radical polymerization of acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat resistant monomer, cage-type polysilsesquioxane and initiator in a solvent; The curing agent is one or a mixture of two of toluene diisocyanate, 1,4-tetramethylxylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; The antistatic agent is one or a mixture of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; The leveling agent is a hydroxyl-containing leveling agent; The solvent is one or a mixture of two or more of ethyl acetate, butanone, cyclohexanone, toluene, methyl isobutyl ketone and butyl acetate.

2. The high temperature resistant antistatic protective film for polarizer according to claim 1, characterized in that: The leveling agent is any one of BYK-370, BYK-SILCLEAN 3700 or BYK-394.

3. The high temperature resistant antistatic protective film for polarizer according to claim 1, characterized in that: The PET substrate film is the abbreviation of polyethylene terephthalate film, and has a thickness of 38 to 75 μm.

4. The high temperature resistant antistatic protective film for polarizer according to claim 1, characterized in that: The release film is a transparent polyester film with a layer of silicon-based release agent coated on the surface, and the thickness is 25-50 μm.

5. The high temperature resistant antistatic protective film for polarizer according to claim 1, 2, 3 or 4, characterized in that: The high temperature resistant acrylate polymer is prepared by free radical polymerization of 36-48 parts by weight of acrylate soft monomer, 7-15 parts by weight of acrylate hard monomer, 5-10 parts by weight of acrylate functional monomer, 10-20 parts by weight of heat resistant monomer, 5-15 parts by weight of cage-type polysilsesquioxane and 0.3-0.5 parts by weight of initiator in 80-100 parts by weight of solvent; The acrylic acid ester soft monomer is one or a mixture of two or more of 2-ethylhexyl acrylate, octadecyl acrylate, isooctyl acrylate, n-butyl acrylate, isobutyl acrylate and ethyl acrylate; The acrylic acid ester hard monomer is one or a mixture of two or more of methyl acrylate, methyl methacrylate, acrylonitrile, isobutyl methacrylate, tert-butyl methacrylate, and vinyl acetate; The acrylate functional monomer is one or a mixture of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, cyclohexyl methacrylate, 1,6-hexanediol diacrylate, 2-methoxyethyl acrylate, 3-ethoxyethyl acrylate, and 2-phenoxyethyl acrylate; The heat-resistant monomer is one or a mixture of two or more of maleimide, N-vinyl pyrrolidone, N-hydroxymethyl acrylamide, and N-vinyl carbazole; The cage-type polysilsesquioxane is one or a mixture of two or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacrylic cage-type polysilsesquioxane, acryl cage-type polysilsesquioxane or octavinyl cage-type polysilsesquioxane.

6. The high temperature resistant antistatic protective film for polarizer according to claim 5, characterized in that: The preparation method of the high temperature resistant acrylate polymer is: The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are uniformly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 60-65° C., cage-type polysilsesquioxane and one third of an initiator are added, and the mixture is kept warm for reaction for 1 h to 1.5 h to obtain a reaction solution; Add the remaining half of the mixed liquid to the reaction liquid, stir and heat to 80-85°C, add the remaining two-thirds of the initiator, react for 3h-3.5h, pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer.

7. A method for preparing a high temperature resistant antistatic protective film for a polarizer, characterized by the steps of: a. Preparation of high temperature resistant acrylic polymer: Ingredients: Take the raw materials of each component according to the ratio of 36-48 parts by weight of acrylate soft monomer, 7-15 parts by weight of acrylate hard monomer, 5-10 parts by weight of acrylate functional monomer, 10-20 parts by weight of heat-resistant monomer, 5-15 parts by weight of cage-type polysilsesquioxane, 0.3-0.5 parts by weight of initiator and 80-100 parts by weight of solvent, and set aside; The acrylate soft monomer, acrylate hard monomer, acrylate functional monomer, heat-resistant monomer and solvent are uniformly mixed to obtain a mixed solution, one half of the mixed solution is added to a reaction container, and when heated to 60-65° C., cage-type polysilsesquioxane and one third of an initiator are added, and the mixture is kept warm for reaction for 1 h to 1.5 h to obtain a reaction solution; Add the remaining half of the mixed solution to the reaction solution, stir and heat to 80-85°C, add the remaining two-thirds of the initiator, react for 3h-3.5h, pour out, add solvent to adjust the solid content to 25.5%, and obtain a high temperature resistant acrylate polymer; The acrylic acid ester soft monomer is one or a mixture of two or more of 2-ethylhexyl acrylate, octadecyl acrylate, isooctyl acrylate, n-butyl acrylate, isobutyl acrylate and ethyl acrylate; The acrylic acid ester hard monomer is one or a mixture of two or more of methyl acrylate, methyl methacrylate, acrylonitrile, isobutyl methacrylate, tert-butyl methacrylate, and vinyl acetate; The acrylate functional monomer is one or a mixture of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, cyclohexyl methacrylate, 1,6-hexanediol diacrylate, 2-methoxyethyl acrylate, 3-ethoxyethyl acrylate, and 2-phenoxyethyl acrylate; The heat-resistant monomer is one or a mixture of two or more of maleimide, N-vinyl pyrrolidone, N-hydroxymethyl acrylamide, and N-vinyl carbazole; The cage-type polysilsesquioxane is one or a mixture of two or more of methacryloyloxypropyl cage-type polysilsesquioxane, methacrylic cage-type polysilsesquioxane, acryl cage-type polysilsesquioxane or octavinyl cage-type polysilsesquioxane; b. Preparation of acrylic pressure-sensitive adhesive: Ingredients: Take the raw materials of each component according to the ratio of 90-100 parts by weight of high temperature resistant acrylic polymer, 1.5-2 parts by weight of curing agent, 1-1.5 parts by weight of antistatic agent, 0.5-1 parts by weight of leveling agent and 20-40 parts by weight of solvent, and set aside; Under normal temperature conditions, the high temperature resistant acrylic polymer and the solvent are first mixed and stirred at a speed of 300 to 700 rpm for 10 to 15 minutes; then an antistatic agent, a leveling agent, and a curing agent are added in sequence, and after each component raw material is added, the mixture is mixed at a speed of 300 to 700 rpm for 5 to 10 minutes until it is uniform, thereby obtaining an acrylic pressure-sensitive adhesive; The curing agent is one or a mixture of two of toluene diisocyanate, 1,4-tetramethylxylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; The antistatic agent is one or a mixture of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; The leveling agent is a hydroxyl-containing leveling agent; The solvent is one or a mixture of two or more of ethyl acetate, butanone, cyclohexanone, toluene, methyl isobutyl ketone, and butyl acetate; c. Preparation of high temperature resistant antistatic protective film for polarizer: The acrylic pressure-sensitive adhesive is coated on the PET substrate film by a coating machine, and cured at a temperature of 120-125° C. for 1-1.5 minutes to form an acrylic pressure-sensitive adhesive layer, and then covered with a release film and aged at a temperature of 60-65° C. for two days to obtain a high-temperature resistant antistatic protective film for polarizers.

8. The method for preparing the high temperature resistant antistatic protective film for polarizer according to claim 7, characterized in that: The leveling agent in step b is any one of BYK-370, BYK-SILCLEAN 3700 or BYK-394.

9. The method for preparing the high temperature resistant antistatic protective film for polarizer according to claim 7, characterized in that: The PET substrate film in step c is the abbreviation of polyethylene terephthalate film, and has a thickness of 38 to 75 μm.

10. The method for preparing the high temperature resistant antistatic protective film for polarizer according to claim 7, characterized in that: The acrylic pressure-sensitive adhesive layer in step c has a thickness of 15 to 20 μm.

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