Liquid crystal light guide plate high-transmittance tpe protective film and preparation method thereof

Abstract

The application relates to the field of protective films and discloses a liquid crystal light guide plate high-transmittance tpe protective film and a preparation method thereof, which comprises SEBS, polypropylene, modified halloysite nanotubes, modified silicon dioxide and an additive; the modified halloysite nanotubes are prepared by the following steps: reacting a functional additive, which is prepared by grafting an isocyanate-oxidized antioxidant component and a modified benzothiazole-containing monomer, with 3-chloropropyl trimethoxysilane, and then grafting on the surface of the halloysite nanotubes; the isocyanate-oxidized antioxidant component is obtained by the following steps: reacting 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and N-hydroxymethyl acrylamide, and then reacting with 2-mercaptoethanol; and then, the isocyanate-oxidized antioxidant component is reacted with isophorone diisocyanate; the modified benzothiazole-containing monomer is prepared by the following steps: reacting 2-aminobenzothiazole and bromoacetyl bromide, and then reacting with 3,5-dihydroxybenzylamine; and the protective film prepared by the application has good heat-oxygen aging resistance, antibacterial property, heat resistance and tensile property.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of protective films, and particularly relates to a high-transparency tpe protective film for a liquid crystal light guide plate and a preparation method thereof. BACKGROUND

[0002] The light guide plate applied to the liquid crystal screen of a mobile phone, a camera and other digital electronic products is a product with high transparency and high purity, and has high standards for production environment and surface quality. However, in the processing, carrying and transportation process of the light guide plate, contact and friction with some parts of the equipment are inevitable, or the surface of the light guide plate is scratched or adheres dust, oil stains and the like due to improper operation, so a protective film needs to be attached to the surface of the light guide plate.

[0003] Thermoplastic elastomer is a new type of high molecular material with high strength of plastic and high elasticity of rubber, and has excellent processability and recyclability, so it has been widely concerned in various fields such as electronic products, automobiles, aerospace, daily necessities and the like. At present, after the protective film applied to the light guide plate is attached to the surface of the light guide plate, the protective film will be affected by temperature and aging phenomenon will occur, so that the protective film cannot be smoothly peeled off after use and residual glue phenomenon occurs, which affects the quality of the light guide plate. The existing technology improves the aging resistance of the protective film by adding small molecules such as hindered phenolic antioxidant and amine antioxidant as antioxidant components, but the hindered phenolic antioxidant and amine antioxidant are prone to volatilization and migration in the process of processing and subsequent use of the protective film, and the long-term antioxidant performance of the protective film cannot be guaranteed, so there are still difficulties in actual application. Moreover, the existing thermoplastic elastomer protective film has problems such as poor heat resistance, low tensile strength and insufficient antibacterial effect, which limits its use range to a certain extent. SUMMARY

[0004] To solve the problems mentioned in the background, the purpose of the present application is to provide a high-transparency tpe protective film for a liquid crystal light guide plate and a preparation method thereof. By adding modified halloysite nanotubes and modified silicon dioxide, the protective film is endowed with good heat-resistant oxygen aging resistance, antibacterial performance, heat resistance and tensile properties.

[0005] The purpose of the present application can be achieved by the following technical solutions.

[0006] A high-transparency tpe protective film for a liquid crystal light guide plate comprises the following components by weight: 45-60 parts of SEBS elastomer, 8-12 parts of polypropylene, 5-10 parts of modified halloysite nanotubes, 2-5 parts of modified silicon dioxide, 1-5 parts of lubricant and 5-15 parts of plasticizer.

[0007] The modified halloysite nanotube is grafted on the surface of halloysite nanotube by using a modified silane coupling agent generated by substitution reaction of a functional additive and 3-chloropropyltrimethoxysilane; wherein the functional additive is prepared by grafting an isocyanate antioxidant component and a modified benzothiazole-containing monomer through chemical reaction;

[0008] The isocyanate antioxidant component is prepared by esterification reaction of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and N-hydroxymethyl acrylamide, followed by thiol-ene click reaction with 2-mercaptoethanol to obtain a hydroxylated antioxidant component, and then by reaction with isophorone diisocyanate; and the modified benzothiazole-containing monomer is prepared by substitution reaction of 2-aminobenzothiazole and bromoacetyl bromide, followed by substitution reaction with 3,5-dihydroxybenzylamine.

[0009] The modified silica is prepared by wrapping silica particles generated by hydrolysis of tetraethyl orthosilicate on a polyacrylic acid core through a sol-gel method.

[0010] Preferably, the lubricant is one or more combinations of stearic acid, polyethylene wax, oxidized polyethylene wax, and paraffin wax; and the plasticizer is one or more combinations of dibutyl phthalate, diisononyl phthalate, tributyl citrate, and acetyl tributyl citrate.

[0011] Preferably, the preparation method of the modified halloysite nanotube comprises the following steps:

[0012] A. Take the isocyanate antioxidant component, the modified benzothiazole-containing monomer, and toluene in a reactor, then add a mixed solution of dibutyltin dilaurate and toluene, and stir at 45-55°C for 10-12h. After the reaction is completed, spin, wash, and dry to obtain the functional additive;

[0013] B. Take the functional additive, 3-chloropropyltrimethoxysilane, triethylamine, and tetrahydrofuran in a reactor, and stir at 70-85°C for 5-8h under nitrogen atmosphere. After the reaction is completed, filter, wash, and dry to obtain the modified silane coupling agent;

[0014] C. Ultrasonically disperse halloysite nanotubes in a mixed solution of anhydrous ethanol and deionized water, then add the modified silane coupling agent, and stir at 60-75°C for 3-6h. After the reaction is completed, centrifuge, wash, and dry to obtain the modified halloysite nanotube.

[0015] Preferably, the preparation method of the isocyanate antioxidant component in step A comprises the following steps:

[0016] (1) Take 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid, 4-dimethylamino pyridine and dichloromethane in a reactor, place in 0-4℃ and nitrogen atmosphere, stir and dissolve, then add 1-ethyl-3(3-dimethylpropylamine) carbodiimide and dichloromethane mixed solution, stir for 1.5-2h, then take N-hydroxymethyl acrylamide dissolved in dichloromethane and add to the reactor, place in 18-22℃ for 3-4h, after the reaction is completed, filter, rotary evaporation, purification, to prepare the double bond grafted antioxidant component;

[0017] (2) Take the double bond grafted antioxidant component and 2-mercaptoethanol in a reactor, add toluene solvent, heat to 45-55℃, add triethylamine and toluene mixed solution, stir for 4-6h, after the reaction is completed, remove unreacted substances by rotary evaporation under reduced pressure, to prepare the hydroxylated antioxidant component;

[0018] (3) Take the hydroxylated antioxidant component, isophorone diisocyanate and toluene in a reactor, then add dibutyltin dilaurate and toluene mixed solution, place in 55-65℃ and stir for 4-6h, after the reaction is completed, rotary evaporation, washing, drying, to prepare the isocyanate antioxidant component.

[0019] Preferably, the molar ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and N-hydroxymethyl acrylamide in step (1) is 1:1-1.5; the molar ratio of the double bond grafted antioxidant component and 2-mercaptoethanol in step (2) is 1:1.5-2.

[0020] Preferably, the molar ratio of the hydroxylated antioxidant component and isophorone diisocyanate in step (3) is 1-1.1:1.

[0021] Preferably, the preparation method of the modified benzothiazole-containing monomer in step A comprises the following steps:

[0022] ①Take 2-amino benzothiazole and triethylamine in a reactor, add dichloromethane solvent, drop 1-bromoacetyl bromide and dichloromethane mixed solution under ice water bath condition, stir for 0.5-1h, after the reaction is completed, remove unreacted substances by rotary evaporation under reduced pressure, to prepare the benzothiazole-containing monomer;

[0023] ②Take the benzothiazole-containing monomer, 3,5-dihydroxybenzylamine and sodium carbonate in a reactor, add N,N-dimethylformamide and tetrahydrofuran mixed solvent, place in 55-70℃ for 2-3h, after the reaction is completed, rotary evaporation, washing, drying, purification, to prepare the modified benzothiazole-containing monomer.

[0024] Preferably, the molar ratio of 2-amino benzothiazole and bromoacetyl bromide in step ① is 1:1-1.2; and the molar ratio of the benzothiazole-containing monomer and 3,5-dihydroxybenzylamine in step ② is 1:1-1.2.

[0025] Preferably, the preparation method of the modified silica comprises the following steps: dissolving polyacrylic acid in ammonia water, mixing with anhydrous ethanol, then adding tetraethyl orthosilicate in batches under magnetic stirring, adjusting the pH value of the system to 5.5-6 using acetic acid after 8-10 h of reaction, stirring and reacting the obtained mixed sol at 55-65 DEG C for 0.5-1 h, cooling in ice water after the reaction is completed, and ultrasonic dispersion for 15-20 min to obtain the modified silica.

[0026] A preparation method of a liquid crystal light guide plate high-transmittance tpe protective film, comprising the following steps:

[0027] S1, each component is weighed by weight parts, SEBS elastomer, polypropylene, modified halloysite nanotube, modified silica, lubricant and plasticizer are added into a mixer, mixed at 50-65 DEG C for 8-12 min to obtain a premix;

[0028] S2, the premix is extruded and granulated in a twin-screw extruder at 185-220 DEG C to obtain a mixture;

[0029] S3, the mixture is blow-molded to prepare a liquid crystal light guide plate high-transmittance tpe protective film.

[0030] The beneficial effects of the present application are:

[0031] The present application utilizes the esterification reaction of hindered phenolic antioxidant 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and N-hydroxymethyl acrylamide to prepare a double bond grafted antioxidant component, then the thiol-alkene click reaction of the double bond grafted antioxidant component and 2-mercaptoethanol to prepare a hydroxylated antioxidant component, and then the reaction of the isocyanate group directly connected with the cyclohexane ring and having high activity in isophorone diisocyanate with the hydroxyl group in the hydroxylated antioxidant component to prepare an isocyanate antioxidant component.

[0032] The application utilizes the reaction of isocyanate groups in the isocyanated antioxidant component and hydroxyl groups in the modified benzothiazole-containing monomer to prepare a functional additive, then utilizes the substitution reaction of ungrafted hydroxyl groups in the functional additive and chlorine atoms in 3-chloropropyltrimethoxysilane to prepare a modified silane coupling agent, and then utilizes the condensation reaction of silicon hydroxyl groups in the modified silane coupling agent and hydroxyl groups on the surface of halloysite nanotubes to prepare modified halloysite nanotubes, so that the hindered phenolic antioxidant is tightly combined on the surface of the halloysite nanotubes through a firm chemical bond, and due to the tubular structure of the halloysite nanotubes, the hindered phenolic antioxidant can be slowly released, thereby limiting the migration of the hindered phenolic antioxidant in the base material, achieving long-acting heat-oxidation aging resistance, and at the same time, the thiazole monomer with antibacterial activity and the amide group and the urethane group with good heat resistance are introduced on the surface of the halloysite nanotubes, improving the antibacterial performance and heat resistance of the protective film, and after the surface modification of the halloysite nanotubes by the modified silane coupling agent, the halloysite nanotubes are relatively uniformly dispersed in the base material, which is conducive to the full play of the performance of the halloysite nanotubes. In addition, the modified silica with a core-shell structure is prepared by using the sol-gel method to wrap the silica particles generated by the catalytic hydrolysis of tetraethyl orthosilicate in ammonia on the inner core of polyacrylic acid, avoiding direct contact of the particles and reducing the generation of agglomeration, and the silica shell layer in the modified silica provides surface hardness, and the polyacrylic acid core absorbs impact energy, which is conducive to improving the flexibility and tensile performance of the protective film while maintaining the wear resistance of the protective film. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the application.

[0034] The preparation method of the isocyanated antioxidant component in Example 1 comprises the following steps:

[0035] (1) 5 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 0.2 g of 4-dimethylaminopyridine and 40 mL of dichloromethane are taken in a reactor, stirred and dissolved under the conditions of 0 DEG C and nitrogen atmosphere, then a mixed solution of 4.1 g of 1-ethyl-3(3-dimethylpropylamine) carbodiimide and 40 mL of dichloromethane is added, stirred for 2 h, then 2.7 g of N-hydroxymethyl acrylamide is dissolved in 10 mL of dichloromethane and added to the reactor, and the reaction is carried out at 20 DEG C for 4 h. After the reaction is completed, filtration, rotary evaporation and purification are carried out to prepare a double bond grafted antioxidant component;

[0036] (2) Take 7.3 g of double bond grafted antioxidant component (Mr = 361.5) and 3.1 g of 2-mercaptoethanol in a reactor, add 50 mL of toluene solvent, heat to 50°C, add a mixed solution of 0.08 g of triethylamine and 10 mL of toluene, stir for 6 h, and after the reaction is completed, remove the unreacted substance by rotary evaporation under reduced pressure to prepare a hydroxylated antioxidant component;

[0037] (3) Take 4.4 g of the hydroxylated antioxidant component (Mr = 439.6), 2.2 g of isophorone diisocyanate, and 40 mL of toluene in a reactor, then add a mixed solution of 0.63 g of dibutyltin dilaurate and 10 mL of toluene, and stir at 65°C for 5 h. After the reaction is completed, rotary evaporation, washing, and drying are performed to prepare an isocyanate- grafted antioxidant component.

[0038] Example 2 A method for preparing a modified benzothiazole-containing monomer includes the following steps:

[0039] ① Take 3 g of 2-aminobenzothiazole and 2.4 g of triethylamine in a reactor, add 50 mL of dichloromethane solvent, and dropwise add a mixed solution of 4.4 g of bromoacetyl bromide and 15 mL of dichloromethane under ice water bath conditions, stir for 0.5 h, and after the reaction is completed, rotary evaporation under reduced pressure and purification are performed to prepare a benzothiazole-containing monomer.

[0040] ② Take 2.7 g of the benzothiazole-containing monomer, 1.7 g of 3,5-dihydroxybenzylamine, and 1.6 g of sodium carbonate in a reactor, add 50 mL of a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and react at 65°C for 3 h. After the reaction is completed, rotary evaporation, washing, drying, and purification are performed to prepare a modified benzothiazole-containing monomer.

[0041] Example 3 A method for preparing a modified halloysite nanotube includes the following steps:

[0042] A. Take 6.6 g of the isocyanate-grafted antioxidant component (Mr = 661.9) prepared in Example 1, 3.3 g of the modified benzothiazole-containing monomer (Mr = 329.3) prepared in Example 2, and 50 mL of toluene in a reactor, then add a mixed solution of 0.63 g of dibutyltin dilaurate and 10 mL of toluene, and stir at 50°C for 12 h. After the reaction is completed, rotary evaporation, washing, and drying are performed to prepare a functional additive.

[0043] B. Take 5 g of the functional additive (Mr = 991.2), 1.2 g of 3-chloropropyltrimethoxysilane, 0.6 g of triethylamine, and 50 mL of tetrahydrofuran in a reactor, stir at 80°C for 6 h in a nitrogen atmosphere, and after the reaction is completed, perform suction filtration, washing, and drying to prepare a modified silane coupling agent.

[0044] C. 5 g of halloysite nanotubes were ultrasonically dispersed in a mixed solution of 90 mL of anhydrous ethanol and 10 mL of deionized water, then 4.2 g of a modified silane coupling agent was added, and the mixture was stirred at 70°C for 4 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain modified halloysite nanotubes.

[0045] A method for preparing modified silica according to Example 4 includes the following steps:

[0046] 0.24 g of polyacrylic acid (Mw = 5000) was dissolved in 4.5 mL of ammonia water, mixed with 90 mL of anhydrous ethanol, then 1.8 mL of tetraethyl orthosilicate was added in five batches at an interval of 1 h under magnetic stirring, the pH value of the system was adjusted to 6 using acetic acid after 10 h of reaction, and the obtained mixed sol was stirred at 60°C for 1 h. After the reaction was completed, the mixture was cooled in ice water and ultrasonically dispersed for 20 min to obtain modified silica.

[0047] A liquid crystal light guide plate high-transmission tpe protective film according to Example 5 includes the following components by weight: 47 parts of SEBS elastomer, 8.5 parts of polypropylene, 5 parts of modified halloysite nanotubes prepared according to Example 3, 2 parts of modified silica prepared according to Example 4, 1.5 parts of lubricant stearic acid, and 6 parts of plasticizer dibutyl phthalate.

[0048] A method for preparing the above-mentioned liquid crystal light guide plate high-transmission tpe protective film includes the following steps:

[0049] S1. The components were weighed according to the weight parts, and the SEBS elastomer, polypropylene, modified halloysite nanotubes, modified silica, lubricant, and plasticizer were added to a mixer, which was mixed at 60°C for 10 min to obtain a premix;

[0050] S2. The premix was extruded and granulated in a twin-screw extruder at 195°C to obtain a mixture;

[0051] S3. The mixture was blow-molded to prepare a liquid crystal light guide plate high-transmission tpe protective film.

[0052] A liquid crystal light guide plate high-transmission tpe protective film according to Example 6 includes the following components by weight: 51 parts of SEBS elastomer, 10 parts of polypropylene, 7 parts of modified halloysite nanotubes prepared according to Example 3, 4 parts of modified silica prepared according to Example 4, 3 parts of lubricant polyethylene wax, and 8 parts of plasticizer diisononyl phthalate.

[0053] The preparation method of the above-mentioned liquid crystal light guide plate high-transmission tpe protective film is the same as that of Example 5.

[0054] Example 7 A liquid crystal light guide plate high-transmittance tpe protective film, comprising the following components by weight: SEBS elastomer 58 parts, polypropylene 12 parts, modified halloysite nanotubes prepared in Example 3 9 parts, modified silicon dioxide prepared in Example 4 5 parts, lubricant oxidized polyethylene wax 4.5 parts, plasticizer tributyl citrate 12 parts.

[0055] The preparation method of the above-mentioned liquid crystal light guide plate high-transmittance tpe protective film is the same as that of Example 5.

[0056] Preparation method of modified halloysite nanotubes in Comparative Example 1, comprising the following steps:

[0057] (1) Take 5g 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 0.2g 4-dimethylaminopyridine and 40mL dichloromethane in a reactor, under 0℃ and nitrogen atmosphere, stir and dissolve, then add a mixed solution of 4.1g 1-ethyl-3(3-dimethylpropylamine) carbodiimide and 40mL dichloromethane, stir for 2h, then take 2.7g N-hydroxymethyl acrylamide dissolved in 10mL dichloromethane and add to the reactor, react at 20℃ for 4h, after the reaction is completed, filter, rotary evaporate and purify to prepare a double bond grafted antioxidant component;

[0058] (2) Take 7.3g double bond grafted antioxidant component (Mr=361.5) and 3.1g 2-mercaptoethanol in a reactor, add 50mL toluene solvent, heat to 50℃, add a mixed solution of 0.08g triethylamine and 10mL toluene, stir for 6h, after the reaction is completed, rotary evaporate under reduced pressure to remove unreacted substances, to prepare a hydroxylated antioxidant component;

[0059] (3) Take 2.2g hydroxylated antioxidant component (Mr=439.6), 1.2g 3-chloropropyltrimethoxysilane, 0.6g triethylamine and 50mL tetrahydrofuran in a reactor, under nitrogen atmosphere, stir and react at 80℃ for 6h, after the reaction is completed, filter, wash and dry to prepare a modified silane coupling agent;

[0060] (4) Take 5g halloysite nanotubes and ultrasonically disperse in a mixed solution of 90mL anhydrous ethanol and 10mL deionized water, then add 4.2g modified silane coupling agent, stir and react at 70℃ for 4h, after the reaction is completed, centrifuge, wash and dry to prepare modified halloysite nanotubes.

[0061] Comparative Example 2 A liquid crystal light guide plate high-transmittance tpe protective film, comprising the following components by weight: SEBS elastomer 58 parts, polypropylene 12 parts, modified halloysite nanotubes prepared in Comparative Example 1 9 parts, modified silicon dioxide prepared in Example 4 5 parts, lubricant oxidized polyethylene wax 4.5 parts, plasticizer tributyl citrate 12 parts.

[0062] The preparation method of the liquid crystal light guide plate high-transmittance TPE protective film is the same as that of Example 5.

[0063] Comparative Example 3 A liquid crystal light guide plate high-transmittance TPE protective film includes the following components by weight: SEBS elastomer 58 parts, polypropylene 12 parts, halloysite nanotubes 9 parts, modified silica prepared in Example 4 5 parts, lubricant oxidized polyethylene wax 4.5 parts, plasticizer tributyl citrate 12 parts, and antioxidant 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid 2 parts.

[0064] The preparation method of the liquid crystal light guide plate high-transmittance TPE protective film is the same as that of Example 5.

[0065] Comparative Example 4 A liquid crystal light guide plate high-transmittance TPE protective film includes the following components by weight: SEBS elastomer 58 parts, polypropylene 12 parts, modified halloysite nanotubes prepared in Example 1 9 parts, silica 5 parts, lubricant oxidized polyethylene wax 4.5 parts, and plasticizer tributyl citrate 12 parts.

[0066] The preparation method of the liquid crystal light guide plate high-transmittance TPE protective film is the same as that of Example 5.

[0067] Performance detection

[0068] The liquid crystal light guide plate high-transmittance TPE protective films prepared in Examples 5-7 and Comparative Examples 2-4 are subjected to performance detection.

[0069] a. The tensile properties of the samples are detected according to GB / T 528-2008; the samples are placed in a TGA-103 thermal gravimetric analyzer, and the initial decomposition temperature of the material is recorded under nitrogen protection at a temperature rise rate of 5°C / min from room temperature to 800°C, to evaluate the heat resistance of the sample; the antibacterial effect of the sample on Escherichia coli and Staphylococcus aureus is detected by the plate count method, and the activated bacterial solution is added to a test tube and diluted to a total number of bacterial colonies of 10 6 CFU / mL, the film material is added to the bacterial solution, placed in a constant temperature incubator, and cultured at 37°C for 24h, then the diluted bacterial solution is coated on agar medium and placed in a constant temperature incubator, and cultured at 37°C for 24h, then the number of bacterial colonies in each culture dish is observed, and the antibacterial rate is calculated as (R0-R1) / R0, where R0 is the number of bacterial colonies without adding the film material, and R1 is the number of bacterial colonies with adding the film material, and the data results are shown in Table 1.

[0070] Table 1 Performance detection results of the samples

[0071]

[0072] As can be seen from the data in Table 1, the protective films prepared in Examples 5-7 have high tensile strength, are not easy to break, and have excellent heat resistance and antibacterial properties. In Comparative Example 2, the modified halloysite nanotubes added are not grafted with the benzothiazole-containing monomer and do not introduce isophorone diisocyanate, and the initial thermal decomposition temperature, E. coli antibacterial rate and S. aureus antibacterial rate are lower than those of Examples 5-7, because the surface of the halloysite nanotubes does not introduce amide groups and urethane groups with good heat resistance, resulting in a decrease in the initial thermal decomposition temperature, and does not introduce thiazole monomers with antibacterial activity, resulting in a decrease in the antibacterial effect. In Comparative Example 3, the halloysite nanotubes are not modified, and the tensile strength, heat resistance and antibacterial effect are lower than those of Examples 5-7, which may be due to the aggregation of the halloysite nanotubes, resulting in a decrease in the tensile strength, and indicates that modifying the halloysite nanotubes can improve the heat resistance and antibacterial properties of the protective film to some extent. In Comparative Example 4, the silica is not modified, and the tensile strength is lower than that of Examples 5-7, indicating that the modified silica with a core-shell structure can improve the tensile properties of the protective film.

[0073] b. The sample was placed in an air heat aging test chamber for 100°C high-temperature thermal oxidation aging, and the aging period was divided into four test periods of 3, 6, 12 and 24 days. Five samples were taken for each period, and each sample was subjected to an oxidation induction time test to evaluate the thermal oxidation aging resistance of the protective film, and the data results are shown in Table 2.

[0074] Table 2: Test results of the thermal oxidation aging resistance of the sample

[0075]

[0076] As can be seen from the data in Table 2, the protective films prepared in Examples 5-7 have a long oxidation induction time, and still maintain a long oxidation induction time after 24 days of thermal oxidation aging process, and have excellent thermal oxidation aging resistance. In Comparative Example 3, the halloysite nanotubes and the antioxidant 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid are directly mixed, and the oxidation induction time is significantly shorter than that of Examples 5-7, which may be due to the fact that the antioxidant component is not grafted on the surface of the halloysite nanotubes, resulting in poor long-term thermal oxidation aging resistance.

[0077] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0078] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all such variations and modifications are intended to be included within the scope of the application as defined in the following claims.

Claims

1. A high-transmittance TPE protective film for a liquid crystal light guide plate, characterized in that, It includes the following components by weight: 45-60 parts of SEBS elastomer, 8-12 parts of polypropylene, 5-10 parts of modified halloysite nanotubes, 2-5 parts of modified silica, 1-5 parts of lubricant, and 5-15 parts of plasticizer. The modified halloysite nanotubes are prepared by grafting a modified silane coupling agent, generated by a substitution reaction between functional additives and 3-chloropropyltrimethoxysilane, onto the surface of halloysite nanotubes; wherein the functional additives are prepared by grafting isocyanate-based antioxidant components with modified benzothiazole-containing monomers using a chemical reaction. The isocyanate-based antioxidant component is prepared by esterification of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and N-hydroxymethylacrylamide followed by a thiol-ene click reaction with 2-mercaptoethanol to obtain a hydroxylated antioxidant component, which is then reacted with isophorone diisocyanate to prepare the antioxidant component. The modified benzothiazole-containing monomer is prepared by substitution of 2-aminobenzothiazole and bromoacetyl bromide followed by a further substitution reaction with 3,5-dihydroxybenzylamine. The modified silica is made by encapsulating silica particles generated from the hydrolysis of tetraethyl orthosilicate onto a polyacrylic acid core using a sol-gel method.

2. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 1, characterized in that, The lubricant is one or more of stearic acid, polyethylene wax, oxidized polyethylene wax, and paraffin wax; the plasticizer is one or more of dibutyl phthalate, diisononyl phthalate, tributyl citrate, and acetylated tributyl citrate.

3. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 1, characterized in that, The method for preparing the modified halloysite nanotubes includes the following steps: A. Take isocyanate-based antioxidant components, modified benzothiazole-containing monomers and toluene into a reactor, then add a mixed solution of dibutyltin dilaurate and toluene, and stir the reaction at 45~55℃ for 10~12h. After the reaction is completed, the functional additive is prepared by rotary evaporation, washing and drying. B. Take the functional additive, 3-chloropropyltrimethoxysilane, triethylamine and tetrahydrofuran into a reactor, and stir the reaction at 70~85℃ for 5~8h in a nitrogen atmosphere. After the reaction is completed, filter, wash and dry to prepare the modified silane coupling agent. C. Take halloysite nanotubes and ultrasonically disperse them in a mixed solution of anhydrous ethanol and deionized water. Then add a modified silane coupling agent and stir the mixture at 60-75°C for 3-6 hours. After the reaction is completed, centrifuge, wash and dry to prepare modified halloysite nanotubes.

4. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 3, characterized in that, The preparation method of the isocyanate-based antioxidant component in step A includes the following steps: (1) Take 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 4-dimethylaminopyridine and dichloromethane in a reactor, place them at 0~4℃ and under a nitrogen atmosphere, stir and dissolve them, then add a mixed solution of 1-ethyl-3-(3-dimethylpropylamine)carbodiimide and dichloromethane, stir for 1.5~2h, then take N-hydroxymethylacrylamide dissolved in dichloromethane and add it to the reactor, place it at 18~22℃ and react for 3~4h, after the reaction is completed, filter, rotary evaporate and purify to prepare double bond grafted antioxidant component; (2) Take the double bond grafted antioxidant component and 2-mercaptoethanol into a reactor, add toluene solvent, heat to 45~55℃, add a mixed solution of triethylamine and toluene, stir and react for 4~6h, and after the reaction is completed, purify by rotary evaporation under reduced pressure to remove unreacted substances and prepare the hydroxylated antioxidant component. (3) Take the hydroxylated antioxidant component, isophorone diisocyanate and toluene into a reactor, then add a mixed solution of dibutyltin dilaurate and toluene, and stir the reaction at 55~65℃ for 4~6h. After the reaction is completed, the isocyanate-based antioxidant component is prepared by rotary evaporation, washing and drying.

5. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 4, characterized in that, In step (1), the molar ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and N-hydroxymethylacrylamide is 1:1~1.5; in step (2), the molar ratio of double bond grafted antioxidant component and 2-mercaptoethanol is 1:1.5~2.

6. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 4, characterized in that, In step (3), the molar ratio of the hydroxylated antioxidant component to isophorone diisocyanate is 1~1.1:

1.

7. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 3, characterized in that, The preparation method of the modified benzothiazole monomer in step A includes the following steps: ① Take 2-aminobenzothiazole and triethylamine in a reactor, add dichloromethane solvent, and under ice-water bath conditions, add a mixed solution of bromoacetyl bromide and dichloromethane dropwise. Stir the reaction for 0.5-1 h. After the reaction is completed, the monomer containing benzothiazole is prepared by rotary evaporation under reduced pressure and purification. ② Take benzothiazole monomer, 3,5-dihydroxybenzylamine and sodium carbonate in a reactor, add N,N-dimethylformamide and tetrahydrofuran mixed solvent, and react at 55~70℃ for 2~3h. After the reaction is completed, the modified benzothiazole monomer is prepared by rotary evaporation, washing, drying and purification.

8. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 7, characterized in that, In step ①, the molar ratio of 2-aminobenzothiazole and bromoacetyl bromide is 1:1 to 1.2; in step ②, the molar ratio of benzothiazole monomer and 3,5-dihydroxybenzylamine is 1:1 to 1.

2.

9. The high-transmittance TPE protective film for liquid crystal light guide plates according to claim 1, characterized in that, The method for preparing the modified silica includes the following steps: dissolving polyacrylic acid in ammonia water, adding anhydrous ethanol and mixing, then adding tetraethyl orthosilicate in batches under magnetic stirring, reacting for 8-10 hours, adjusting the pH of the system to 5.5-6 using acetic acid, placing the resulting mixed sol at 55-65℃ and stirring for 0.5-1 hours, cooling in ice water after the reaction is complete, and ultrasonically dispersing for 15-20 minutes to prepare the modified silica.

10. A method for preparing a high-transmittance TPE protective film for a liquid crystal light guide plate according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Weigh each component according to the weight parts, add SEBS elastomer, polypropylene, modified halloysite nanotubes, modified silica, lubricant and plasticizer into a mixer, and mix at 50~65℃ for 8~12 minutes to obtain a premix. S2. The premixed material is extruded and granulated in a twin-screw extruder at 185~220℃ to obtain the mixture. S3. The mixture is blow-molded to prepare a high-transmittance TPE protective film for the liquid crystal light guide plate.

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