A stain-resistant transparent PET protective film and its preparation method

Abstract

This invention discloses a stain-resistant transparent PET protective film and its preparation method. The PET protective film comprises the following raw materials in parts by weight: 100-120 parts modified PET, 8-10 parts modified silica, and 0.3-0.5 parts benzophenone. The raw materials are melt-blown into a film and then treated with ultraviolet light to obtain the PET protective film. During the pretreatment of the PET protective film with ultraviolet light, the double bonds on the PET molecular chain can graft onto the thiol groups on the modified silica, thereby increasing the grafting sites and forming a cross-linked network. The cross-linked network can fill the gaps between molecules, reduce the surface porosity, and hinder the penetration of pollutants. The PET main molecular chain contains organosilicon segments, and the sides of the main molecular chain are dispersed with freely moving fluorinated organosilicon segments, which can effectively reduce the surface energy of the PET protective film, thereby forming an ultra-low surface energy interface and effectively preventing the adhesion of pollutants.

Description

Technical Field

[0001] This invention relates to the field of PET film preparation technology, specifically to a stain-resistant transparent PET protective film and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) film is widely used in screen protection for various electronic display devices, optical lens protection, architectural glass films, automotive interior protection, and high-end packaging materials due to its excellent mechanical properties, optical transparency, chemical stability, ease of processing, and relatively low cost. The main function of PET protective film is to prevent the substrate surface from being scratched, worn, contaminated, or chemically corroded during processing, transportation, storage, and use. However, with the widespread use of electronic products (such as smartphones, tablets, laptops, smartwatches, and automotive displays) and the increasing demands of users for device appearance, cleanliness, and user experience, conventional transparent PET protective films have revealed a significant drawback in practical applications: the surface is easily stained with fingerprints, grease, sweat, dust, and other contaminants, and is difficult to clean. Summary of the Invention

[0003] The purpose of this invention is to provide a stain-resistant transparent PET protective film and its preparation method, thereby solving the problem of poor stain resistance in current PET protective films.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A method for preparing a stain-resistant transparent PET protective film, specifically including the following steps:

[0006] Step A1: Disperse nano-silica in ethanol, stir and add deionized water and 3-mercaptopropyltrimethoxysilane at a speed of 300-500 r / min and a temperature of 60-70℃, and react for 4-6 h to obtain modified silica.

[0007] Step A2: Terephthalic acid, modified monomer, ethylene glycol and antimony trioxide are mixed evenly and reacted at a temperature of 230-250℃ and a pressure of 0.3-0.4MPa for 8-10 hours. The temperature is then raised to 260-280℃ and the reaction is carried out at a pressure of 50-60Pa for 40-50 minutes to obtain modified PET.

[0008] Step A3: Weigh the following raw materials in parts by weight: 100-120 parts modified PET, 8-10 parts modified silica, and 0.3-0.5 parts benzophenone. Extrude and blow-blow the raw materials at temperatures of 275℃, 282℃, 285℃, 285℃, and 280℃ in each zone, and at a die temperature of 270℃ to obtain a pretreated PET protective film. Irradiate the pretreated PET protective film with 365nm ultraviolet light for 10-15s to obtain a stain-resistant transparent PET protective film.

[0009] Furthermore, the amount of 3-mercaptopropyltrimethoxysilane used in step A1 is 3% of the mass of nano-silica.

[0010] Furthermore, in step A2, the molar ratio of terephthalic acid and ethylene glycol of the modified monomer is 5:1:6.6, and the amount of antimony trioxide used is 3% of the total mass of terephthalic acid and ethylene glycol of the modified monomer.

[0011] Furthermore, the modified monomer is prepared by the following steps:

[0012] Step B1: Mix octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide evenly, purge with nitrogen for protection, and react at a speed of 200-300 r / min and a temperature of 90-95℃ for 10-15 h. Then raise the temperature to 105-110℃ and react for 2-3 h to obtain epoxy polysiloxane.

[0013] Step B2: Mix epoxy polysiloxane, ethyl acrylate, chloroplatinic acid and DMF evenly, purge with nitrogen, and react for 6-8 hours at a speed of 150-200 r / min and a temperature of 75-85℃ to obtain pretreated polysiloxane. Mix the pretreated polysiloxane and toluene evenly, purge with nitrogen, and stir and add diethanolamine at a speed of 150-200 r / min and a temperature of 70-80℃ to obtain functionalized polysiloxane.

[0014] Step B3: Mix functionalized polysiloxane, triethylamine and DMF evenly, stir and add 3-chloroethylene at a speed of 200-300 r / min and a temperature of 10-15℃, and react for 3-5 h to obtain modified polysiloxane. Mix modified polysiloxane, trichlorosilane, chloroplatinic acid and DMF evenly, purge with nitrogen, and react for 6-8 h at a speed of 120-150 r / min and a temperature of 75-85℃ to obtain polysiloxane modifier.

[0015] Step B4: Mix lithium dimethylvinylsilane and tetrahydrofuran evenly. Stir and add 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane at 150-200 r / min and 0°C. Heat to 25-30°C and react for 7-9 h. Add polysiloxane modifier and continue the reaction for 1-1.5 h to obtain pretreated monomer. Mix pretreated monomer, deionized water and DMF evenly. Stir and add sodium hydroxide solution at 300-500 r / min and 5-10°C. React for 4-5 h. Adjust pH to acidic to obtain modified monomer.

[0016] Furthermore, the ratio of octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide in step B1 is 1 mol: 0.2 mol: 1.5 mol: 1 mol: 14 mL: 40 mL.

[0017] Furthermore, in step B2, the molar ratio of epoxy polysiloxane to ethyl acrylate is 1:2, the amount of chloroplatinic acid is 1‰ of the mass of ethyl acrylate, and the molar ratio of epoxy groups on the pretreated polysiloxane to diethanolamine is 1:1.

[0018] Furthermore, in step B3, the molar ratio of hydroxyl groups, triethylamine, and 3-chloroethylene on the functionalized polysiloxane is 1:1.2:1, the molar ratio of double bonds and trichlorosilane on the modified polysiloxane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0019] Furthermore, in step B4, the molar ratio of Si-Cl bonds on lithium dimethylvinylsilane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, and polysiloxane modifier is 1:5:1, the ratio of pretreatment monomer, deionized water, DMF, and sodium hydroxide solution is 5g:20mL:20mL:12mL, and the mass fraction of sodium hydroxide solution is 20%.

[0020] The beneficial effects of the present invention are as follows: The present invention prepares a stain-resistant transparent PET protective film comprising the following raw materials: modified PET, modified silica and benzophenone. The raw materials are melt-blown into a film and then treated with ultraviolet light to obtain a PET protective film. The modified silica is prepared by treating nano silica with 3-mercaptopropyltrimethoxysilane to graft mercapto groups onto the surface.

[0021] Modified PET is prepared by esterification and polycondensation of terephthalic acid, modifying monomers, and ethylene glycol. The modifying monomer is prepared by ring-opening octamethylcyclotetrasiloxane, followed by hydrolytic condensation with 3-glycidyl etheroxypropylmethyldimethoxysilane, and finally end-capped with 1,1,3,3-tetramethyldisiloxane to obtain epoxy polysiloxane. The epoxy polysiloxane is then reacted with ethyl acrylate, causing the Si-H bonds on the epoxy polysiloxane to react with the double bonds on the ethyl acrylate, yielding a pretreated polysiloxane. The pretreated polysiloxane is then reacted with diethanolamine, causing the epoxy groups on the pretreated polysiloxane to react with the secondary amine groups on the diethanolamine, yielding a functionalized polysiloxane. Finally, the functionalized polysiloxane is reacted with 3- The reaction of vinyl chloride allows the hydroxyl groups on the functionalized polysiloxane to react with the chlorine atoms on 3-chloroethylene, yielding a modified polysiloxane. The modified polysiloxane is then reacted with trichlorosilane, causing the double bonds on the modified polysiloxane to react with the Si-H bonds on the trichlorosilane, yielding a polysiloxane modifier. Using lithium dimethylvinylsilanolate as an initiator and 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane as a monomer, the polysiloxane modifier is added, causing the Si-Cl bonds on the polysiloxane modifier to react with the lithium silanolate, yielding a pretreated monomer. The pretreated monomer is then hydrolyzed to deprotect it, converting the ester groups to carboxyl groups, yielding the modified monomer.

[0022] When the pretreated PET protective film is treated with ultraviolet light, the double bonds on the PET molecular chain can graft onto the thiol groups on the modified silica, thereby increasing the grafting sites and forming a cross-linked network. The cross-linked network can fill the gaps between molecules, reduce the surface porosity, and hinder the penetration of pollutants. The PET main molecular chain contains organosilicon segments, and the two sides of the main molecular chain are dispersed with freely moving fluorinated organosilicon segments, which can effectively reduce the surface energy of the PET protective film, thereby forming an ultra-low surface energy interface and effectively preventing the adhesion of pollutants. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: A method for preparing a stain-resistant transparent PET protective film, specifically including the following steps:

[0025] Step A1: Disperse nano-silica in ethanol, stir and add deionized water and 3-mercaptopropyltrimethoxysilane at a speed of 300 r / min and a temperature of 60℃, and react for 4 h to obtain modified silica.

[0026] Step A2: Terephthalic acid, modified monomer, ethylene glycol and antimony trioxide are mixed evenly and reacted at 230℃ and 0.3MPa for 8 hours. The temperature is then raised to 260℃ and the reaction is carried out at 50Pa for 40 minutes to obtain modified PET.

[0027] Step A3: Weigh the following raw materials in parts by weight: 100 parts modified PET, 8 parts modified silica and 0.3 parts benzophenone. Extrude and blow-blow the raw materials at temperatures of 275℃, 282℃, 285℃, 285℃ and 280℃ in each zone and at a die temperature of 270℃ to obtain a pretreated PET protective film. Irradiate the pretreated PET protective film with 365nm ultraviolet light for 10s to obtain a stain-resistant transparent PET protective film.

[0028] The amount of 3-mercaptopropyltrimethoxysilane used in step A1 is 3% of the mass of nano-silica.

[0029] The molar ratio of terephthalic acid and modified monomer ethylene glycol in step A2 is 5:1:6.6, and the amount of antimony trioxide used is 3% of the total mass of terephthalic acid and modified monomer ethylene glycol.

[0030] The modified monomer is prepared by the following steps:

[0031] Step B1: Octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide are mixed evenly, and nitrogen gas is introduced for protection. The mixture is reacted at 200 r / min and 90℃ for 10 h, and then the temperature is raised to 105℃ and reacted for 2 h to obtain epoxy polysiloxane.

[0032] Step B2: Epoxy polysiloxane, ethyl acrylate, chloroplatinic acid and DMF are mixed evenly, and nitrogen gas is introduced for protection. The mixture is reacted for 6 hours at a speed of 150 r / min and a temperature of 75°C to obtain pretreated polysiloxane. The pretreated polysiloxane and toluene are mixed evenly, and nitrogen gas is introduced for protection. The mixture is stirred and diethanolamine is added at a speed of 150 r / min and a temperature of 70°C. The mixture is reacted for 8 hours to obtain functionalized polysiloxane.

[0033] Step B3: Mix functionalized polysiloxane, triethylamine and DMF evenly, stir and add 3-chloroethylene at 200 r / min and 10℃, and react for 3 h to obtain modified polysiloxane. Mix modified polysiloxane, trichlorosilane, chloroplatinic acid and DMF evenly, purge with nitrogen, and react for 6 h at 120 r / min and 75℃ to obtain polysiloxane modifier.

[0034] Step B4: Mix lithium dimethylvinylsilane and tetrahydrofuran evenly. Stir and add 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane at 150 r / min and 0°C. Heat to 25°C and react for 7 h. Add polysiloxane modifier and continue reaction for 1 h to obtain pretreated monomer. Mix pretreated monomer, deionized water and DMF evenly. Stir and add sodium hydroxide solution at 300 r / min and 5°C and react for 4 h. Adjust pH to acidic to obtain modified monomer.

[0035] The ratio of octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide in step B1 is 1 mol: 0.2 mol: 1.5 mol: 1 mol: 14 mL: 40 mL.

[0036] In step B2, the molar ratio of epoxy polysiloxane to ethyl acrylate is 1:2, the amount of chloroplatinic acid is 1‰ of the mass of ethyl acrylate, and the molar ratio of epoxy groups on the pretreated polysiloxane to diethanolamine is 1:1.

[0037] In step B3, the molar ratio of hydroxyl groups, triethylamine, and 3-chloroethylene on the functionalized polysiloxane is 1:1.2:1, the molar ratio of double bonds and trichlorosilane on the modified polysiloxane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0038] The molar ratio of Si-Cl bonds on lithium dimethylvinylsilane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and polysiloxane modifier in step B4 is 1:5:1. The ratio of the amount of pretreatment monomer, deionized water, DMF and sodium hydroxide solution is 5g:20mL:20mL:12mL, and the mass fraction of sodium hydroxide solution is 20%.

[0039] Example 2, a method for preparing a stain-resistant transparent PET protective film, specifically includes the following steps:

[0040] Step A1: Disperse nano-silica in ethanol, stir and add deionized water and 3-mercaptopropyltrimethoxysilane at a speed of 300 r / min and a temperature of 65℃, and react for 5 h to obtain modified silica.

[0041] Step A2: Terephthalic acid, modified monomer, ethylene glycol and antimony trioxide are mixed evenly and reacted at 240℃ and 0.4MPa for 9 hours. The temperature is then raised to 270℃ and the reaction is carried out at 55Pa for 45 minutes to obtain modified PET.

[0042] Step A3: Weigh the following raw materials in parts by weight: 110 parts modified PET, 9 parts modified silica, and 0.4 parts benzophenone. Extrude and blow-blow the raw materials at temperatures of 275℃, 282℃, 285℃, 285℃, and 280℃ in each zone, and at a die temperature of 270℃ to obtain a pretreated PET protective film. Irradiate the pretreated PET protective film with 365nm ultraviolet light for 13s to obtain a stain-resistant transparent PET protective film.

[0043] The amount of 3-mercaptopropyltrimethoxysilane used in step A1 is 3% of the mass of nano-silica.

[0044] The molar ratio of terephthalic acid and modified monomer ethylene glycol in step A2 is 5:1:6.6, and the amount of antimony trioxide used is 3% of the total mass of terephthalic acid and modified monomer ethylene glycol.

[0045] The modified monomer is prepared by the following steps:

[0046] Step B1: Octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide are mixed evenly, and nitrogen gas is introduced for protection. The mixture is reacted at 300 r / min and 90 °C for 13 h. Then the temperature is raised to 108 °C and the mixture is reacted for 3 h to obtain epoxy polysiloxane.

[0047] Step B2: Epoxy polysiloxane, ethyl acrylate, chloroplatinic acid and DMF are mixed evenly, and nitrogen gas is introduced for protection. The mixture is reacted for 7 hours at a speed of 150 r / min and a temperature of 80°C to obtain pretreated polysiloxane. The pretreated polysiloxane and toluene are mixed evenly, and nitrogen gas is introduced for protection. The mixture is stirred and diethanolamine is added at a speed of 150 r / min and a temperature of 75°C. The mixture is reacted for 9 hours to obtain functionalized polysiloxane.

[0048] Step B3: The functionalized polysiloxane, triethylamine and DMF are mixed evenly. Under the conditions of 200 r / min and 15℃, 3-chloroethylene is added and the mixture is stirred and reacted for 4 h to obtain the modified polysiloxane. The modified polysiloxane, trichlorosilane, chloroplatinic acid and DMF are mixed evenly and nitrogen gas is introduced for protection. The mixture is reacted for 7 h at 120 r / min and 80℃ to obtain the polysiloxane modifier.

[0049] Step B4: Mix lithium dimethylvinylsilane and tetrahydrofuran evenly. Stir and add 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane at 150 r / min and 0°C. Heat to 28°C and react for 8 h. Add polysiloxane modifier and continue reaction for 1.3 h to obtain pretreated monomer. Mix pretreated monomer, deionized water and DMF evenly. Stir and add sodium hydroxide solution at 300 r / min and 8°C and react for 5 h. Adjust pH to acidic to obtain modified monomer.

[0050] The ratio of octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide in step B1 is 1 mol: 0.2 mol: 1.5 mol: 1 mol: 14 mL: 40 mL.

[0051] In step B2, the molar ratio of epoxy polysiloxane to ethyl acrylate is 1:2, the amount of chloroplatinic acid is 1‰ of the mass of ethyl acrylate, and the molar ratio of epoxy groups on the pretreated polysiloxane to diethanolamine is 1:1.

[0052] In step B3, the molar ratio of hydroxyl groups, triethylamine, and 3-chloroethylene on the functionalized polysiloxane is 1:1.2:1, the molar ratio of double bonds and trichlorosilane on the modified polysiloxane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0053] The molar ratio of Si-Cl bonds on lithium dimethylvinylsilane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and polysiloxane modifier in step B4 is 1:5:1. The ratio of the amount of pretreatment monomer, deionized water, DMF and sodium hydroxide solution is 5g:20mL:20mL:12mL, and the mass fraction of sodium hydroxide solution is 20%.

[0054] Example 3, a method for preparing a stain-resistant transparent PET protective film, specifically includes the following steps:

[0055] Step A1: Disperse nano-silica in ethanol, stir and add deionized water and 3-mercaptopropyltrimethoxysilane at a speed of 500 r / min and a temperature of 70℃, and react for 6 h to obtain modified silica.

[0056] Step A2: Terephthalic acid, modified monomer, ethylene glycol and antimony trioxide are mixed evenly and reacted at 250℃ and 0.3-0.4MPa for 10 hours. The temperature is then raised to 280℃ and the reaction is carried out at 60Pa for 50 minutes to obtain modified PET.

[0057] Step A3: Weigh the following raw materials in parts by weight: 120 parts modified PET, 10 parts modified silica and 0.5 parts benzophenone. Extrude and blow-blow the raw materials at temperatures of 275℃, 282℃, 285℃, 285℃ and 280℃ in each zone, and at a die temperature of 270℃ to obtain a pretreated PET protective film. Irradiate the pretreated PET protective film with 365nm ultraviolet light for 15s to obtain a stain-resistant transparent PET protective film.

[0058] The amount of 3-mercaptopropyltrimethoxysilane used in step A1 is 3% of the mass of nano-silica.

[0059] The molar ratio of terephthalic acid and modified monomer ethylene glycol in step A2 is 5:1:6.6, and the amount of antimony trioxide used is 3% of the total mass of terephthalic acid and modified monomer ethylene glycol.

[0060] The modified monomer is prepared by the following steps:

[0061] Step B1: Octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide are mixed evenly, and nitrogen gas is introduced for protection. The mixture is reacted at 300 r / min and 95℃ for 15 h, and then the temperature is raised to 110℃ and reacted for 3 h to obtain epoxy polysiloxane.

[0062] Step B2: Epoxy polysiloxane, ethyl acrylate, chloroplatinic acid and DMF are mixed evenly, and nitrogen gas is introduced for protection. The mixture is reacted for 8 hours at a speed of 200 r / min and a temperature of 85°C to obtain pretreated polysiloxane. The pretreated polysiloxane and toluene are mixed evenly, and nitrogen gas is introduced for protection. The mixture is stirred and diethanolamine is added at a speed of 200 r / min and a temperature of 80°C. The mixture is reacted for 10 hours to obtain functionalized polysiloxane.

[0063] Step B3: The functionalized polysiloxane, triethylamine and DMF are mixed evenly, and 3-chloroethylene is added under the conditions of 300 r / min and 15℃. The mixture is stirred and reacted for 5 h to obtain the modified polysiloxane. The modified polysiloxane, trichlorosilane, chloroplatinic acid and DMF are mixed evenly, and nitrogen gas is introduced for protection. The mixture is reacted for 8 h under the conditions of 150 r / min and 85℃ to obtain the polysiloxane modifier.

[0064] Step B4: Mix lithium dimethylvinylsilane and tetrahydrofuran evenly. Stir and add 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane at 200 r / min and 0°C. Heat to 30°C and react for 9 h. Add polysiloxane modifier and continue reaction for 1.5 h to obtain pretreated monomer. Mix pretreated monomer, deionized water and DMF evenly. Stir and add sodium hydroxide solution at 500 r / min and 10°C and react for 5 h. Adjust pH to acidic to obtain modified monomer.

[0065] The ratio of octamethylcyclotetrasiloxane, 3-glycidyl etheroxypropylmethyldimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide in step B1 is 1 mol: 0.2 mol: 1.5 mol: 1 mol: 14 mL: 40 mL.

[0066] In step B2, the molar ratio of epoxy polysiloxane to ethyl acrylate is 1:2, the amount of chloroplatinic acid is 1‰ of the mass of ethyl acrylate, and the molar ratio of epoxy groups on the pretreated polysiloxane to diethanolamine is 1:1.

[0067] In step B3, the molar ratio of hydroxyl groups, triethylamine, and 3-chloroethylene on the functionalized polysiloxane is 1:1.2:1, the molar ratio of double bonds and trichlorosilane on the modified polysiloxane is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of trichlorosilane.

[0068] The molar ratio of Si-Cl bonds on lithium dimethylvinylsilane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and polysiloxane modifier in step B4 is 1:5:1. The ratio of the amount of pretreatment monomer, deionized water, DMF and sodium hydroxide solution is 5g:20mL:20mL:12mL, and the mass fraction of sodium hydroxide solution is 20%.

[0069] Comparative Example 1: This comparative example uses nano-silica instead of modified silica, while the other steps are the same as in Example 1.

[0070] Comparative Example 2: Compared with Example 1, this comparative example used octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide to mix evenly, under nitrogen protection, and reacted at 200 r / min and 90°C for 10 h. Then the temperature was raised to 105°C and reacted for 2 h. The product obtained replaced the epoxy polysiloxane and was mixed evenly with acrylic acid, chloroplatinic acid and DMF. Under nitrogen protection, it was reacted at 150 r / min and 75°C for 6 h. The monomer obtained replaced the modified monomer. The remaining steps were the same.

[0071] Comparative Example 3: Compared with Example 1, this comparative example uses hexamethylcyclotrisiloxane instead of 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, while the other steps are the same.

[0072] The PET protective films prepared in Examples 1-3 and Comparative Examples 1-3 were tested with the pollutants of Group 1, Group 2 and Group 3 respectively, according to the surface stain resistance test method 1 in GB / T17657-2022. Group 1 and Group 2 were exposed to the pollutants for 16 hours at room temperature, and Group 3 was exposed to the pollutants for 10 minutes at room temperature. The test results are shown in Table 1 below.

[0073] Table 1

[0074]

[0075] As shown in the table above, this application has excellent stain resistance.

[0076] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a stain resistant transparent PET protective film, characterized by: Specifically comprising the following steps: Step A1: dispersing nano-silica in ethanol, stirring and adding deionized water and 3-mercaptopropyl trimethoxysilane, and reacting to prepare modified silica; Step A2: mixing terephthalic acid, modified monomer, ethylene glycol and antimony trioxide and reacting to prepare modified PET; Step A3: weighing the following raw materials: modified PET 100-120 parts, modified silica 8-10 parts and benzophenone 0.3-0.5 parts, extruding and blowing the raw materials into a film to prepare a pretreated PET protective film, and treating the pretreated PET protective film with 365nm ultraviolet light to prepare a stain-resistant transparent PET protective film; The modified monomer is prepared by the following steps: Step B1: mixing octamethylcyclotetrasiloxane, 3-glycidyl ether oxypropyl methyl dimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide uniformly, protecting with nitrogen, and reacting to prepare an epoxy polysiloxane; Step B2: mixing the epoxy polysiloxane, ethyl acrylate, chloroplatinic acid and DMF uniformly, protecting with nitrogen, and reacting to prepare a pretreated polysiloxane, mixing the pretreated polysiloxane and toluene uniformly, protecting with nitrogen, stirring and adding diethanolamine, and reacting to prepare a functionalized polysiloxane; Step B3: mixing the functionalized polysiloxane, triethylamine and DMF, stirring and adding 3-chlorovinyl, and reacting to prepare a modified polysiloxane, mixing the modified polysiloxane, trichlorosilane, chloroplatinic acid and DMF uniformly, protecting with nitrogen, and reacting to prepare a polysiloxane modifier; Step B4: mixing dimethylvinylsilanol lithium and tetrahydrofuran, stirring and adding 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane, reacting after warming, adding the polysiloxane modifier, and continuing to react for 1-1.5h to prepare a pretreated monomer, mixing the pretreated monomer, deionized water and DMF, stirring and adding a sodium hydroxide solution, and reacting to adjust the pH to be acidic to prepare a modified monomer.

2. The method of claim 1, wherein the method is characterized by: The amount of 3-mercaptopropyl trimethoxysilane in step A1 is 3% of the mass of nano-silica.

3. The method of claim 1, wherein the method further comprises: The molar ratio of terephthalic acid, modified monomer and ethylene glycol in step A2 is 5:1:6.

6.

4. The method of claim 1, wherein the method further comprises: The amounts of octamethylcyclotetrasiloxane, 3-glycidyl ether oxypropyl methyl dimethoxysilane, tetramethylammonium hydroxide, 1,1,3,3-tetramethyldisiloxane, deionized water and dimethyl sulfoxide in step B1 are 1mol:0.2mol:1.5mol:1mol:14mL:40mL.

5. The method of claim 1, wherein the method further comprises: The molar ratio of epoxy polysiloxane and ethyl acrylate in step B2 is 1:2, and the molar ratio of epoxy groups on the pretreated polysiloxane and diethanolamine is 1:

1.

6. The method of claim 1, wherein the method further comprises: The molar ratio of hydroxyl groups on the functionalized polysiloxane, triethylamine and 3-chlorovinyl in step B3 is 1:1.2:1, and the molar ratio of double bonds on the modified polysiloxane and trichlorosilane is 1:

1.

7. The method of claim 1, wherein the method further comprises: The molar ratio of dimethylvinylsilanol lithium described in step B4, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane and Si-Cl bond on polysiloxane modifier is 1:5:1, the ratio of pretreatment monomer, deionized water, DMF and sodium hydroxide solution is 5g:20mL:20mL:12mL.

8. A stain resistant clear PET protective film characterized by: Prepared according to the preparation method of any one of claims 1-7. Prepared according to the preparation method of any one of claims 1-7.

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