A polyester film for automotive screens and a method for producing the same

Abstract

The present application relates to the technical field of polyester film, and particularly relates to a polyester film for automobile screen and a preparation method thereof. The polyester film for automobile screen comprises a polyester base film and a functional coating, the functional coating is obtained by coating a functional coating liquid on the surface of the polyester base film; the functional coating liquid is composed of the following raw materials in parts by weight: 20-40 parts by weight of water-based polyurethane emulsion, 8-15 parts by weight of organic silicon resin, 2-6 parts by weight of tackifier, 2-4 parts by weight of emulsifier, 0.5-2 parts by weight of curing agent, 1-3 parts by weight of film forming agent, 15-30 parts by weight of ethylene glycol dimethyl ether, 5-12 parts by weight of functional additive, 40-70 parts by weight of water, and the functional additive is a graphene-silicon dioxide composite. The polyester film for automobile screen prepared by the present application has good mechanical properties, scratch resistance and anti-dazzling effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyester film, in particular to a polyester film for automobile screen and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the automobile industry, automobile screens, as an important part of driving information display and entertainment systems, have increasing protection and functional needs. Polyester films are widely used in the surface protection layer or optical functional layer of automobile screens due to their excellent mechanical properties, transparency, and weather resistance. Traditional automobile screen protection films mainly use ordinary plastic films. Although these films can provide some physical protection, they are prone to surface scratches, poor anti-fingerprint performance, insufficient anti-glare effect, and other problems during long-term use, making it difficult to meet the needs of high-end automobile screens for durability and visual comfort.

[0003] To meet the needs of automobile screens for high-performance protection films, developing polyester films with multiple functions has become a research focus. Functional coating is one of the key technologies for achieving high performance of polyester films. Functional coating can form a thin film with specific functions on the surface of the polyester base film by coating a specific coating liquid, thereby endowing the polyester film with anti-static, anti-glare, self-repairing, wear-resistant, and other functions. However, existing functional coating technologies have many problems, such as poor adhesion, unstable optical performance, and single function, which limit their application in automobile screen protection films.

[0004] In terms of functional additives, the composite of graphene and silica is used to enhance the performance of the coating due to its synergistic effect. However, in existing composite technologies, the bonding force between graphene and silica is weak, and the interface compatibility is poor, resulting in insufficient dispersion and stability of the composite in the coating. Existing technologies prepare graphene-silica composites by physical mixing method, but do not solve the interface bonding problem, and the enhancement effect of functional additives is limited. In addition, traditional coupling agents have single modification effect on the composite system, making it difficult to simultaneously optimize the adhesion, wear resistance, and optical performance of the coating.

[0005] Therefore, there is an urgent need to develop a new type of polyester film with a functional coating that has excellent wear resistance, anti-fingerprint property, anti-glare property, and environmental stability, while also having high light transmittance and low haze. By optimizing the preparation process of graphene-silica composite and the formula of functional coating liquid, it is expected to solve the problems of insufficient coating performance and poor scratch resistance in existing technologies, and meet the needs of automobile screens for high-performance polyester films. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a polyester film for automobile screen and a preparation method thereof.

[0007] To solve the above technical problems, the technical scheme adopted by the present application is:

[0008] A polyester film for automobile screen, comprising a polyester base film and a functional coating, the functional coating is obtained by coating a functional coating liquid on the surface of the polyester base film; the functional coating liquid is composed of the following raw materials by weight: 20-40 parts by weight of water-based polyurethane emulsion, 8-15 parts by weight of silicone resin, 2-6 parts by weight of tackifier, 2-4 parts by weight of emulsifier, 0.5-2 parts by weight of curing agent, 1-3 parts by weight of film-forming agent, 15-30 parts by weight of ethylene glycol dimethyl ether, 5-12 parts by weight of functional additives, 40-70 parts by weight of water, the functional additives are graphene-silicon dioxide composite.

[0009] The automobile screen is exposed to high temperature and ultraviolet light for a long time, and the ordinary coating is prone to yellowing or degradation. Indium doping can effectively increase the thermal decomposition temperature of graphene oxide, thereby inhibiting the high-temperature fracture of the polyurethane segment. However, directly adding traditional indium oxide to the coating has poor dispersibility and poor compatibility with the matrix, which is easy to agglomerate, affecting the overall performance of the polyester film. The inventors found that doping indium metal into graphene oxide can not only effectively improve the interfacial compatibility of graphene oxide and the polyurethane matrix, but also can relieve external impact due to the ductility of indium, so that the coating is not easy to crack when stretched or bent, effectively solving the problem of coating peeling or micro-cracks.

[0010] Graphene oxide has extremely high specific surface area and excellent mechanical properties, which can significantly improve the scratch resistance of the polyester film and avoid scratches on the screen due to frequent touch or wiping; and its two-dimensional sheet structure can slip and disperse stress when stretched, so that the film does not crack when bent, meeting the demand of automobile curved screen.

[0011] Nano-silicon dioxide can form a controllable rough surface in the coating due to its small particle size, reduce specular reflection through light scattering, reduce interface light reflection, improve light transmittance, and improve anti-dazzling effect.

[0012] The specific reaction mechanism is as follows: S1, graphene oxide and indium chloride are used as main reaction raw materials, graphene oxide layers are peeled off by ultrasonic treatment to expose more active sites, and indium-doped graphene oxide is obtained by coordination of indium ions with carboxyl and hydroxyl groups in graphene oxide under microwave heating, so as to improve dispersion stability; S2, nano-silicon dioxide is used as main raw material, and is activated by etching in hydrochloric acid to increase its surface area and improve reaction activity, and silane-modified nano-silicon dioxide is obtained by hydrolysis and condensation of the coupling agent to enhance the compatibility with waterborne polyurethane; S3, indium-doped graphene oxide and silane-modified nano-silicon dioxide are used as reaction raw materials, and under the condition of heating and stirring, the carboxyl or hydroxyl groups on the surface of indium-doped graphene oxide can react with the amino or carboxyl groups in the silane-modified nano-silicon dioxide to effectively connect indium-doped graphene oxide and nano-silicon dioxide together to form a three-dimensional network structure, thereby improving the overall performance of the polyester film.

[0013] Preferably, the preparation method of the graphene-silicon dioxide composite is as follows:

[0014] S1, 3-8 parts by weight of graphene oxide and 80-150 parts by weight of ethanol aqueous solution are mixed and ultrasonically dispersed, 8-15 parts by weight of 4-8 wt% indium chloride aqueous solution is added, ultrasonic dispersion is continued for 0.5-2 h, and then the mixture is placed in a microwave with a power of 400-800 W for heating for 5-10 min to obtain indium-doped graphene oxide;

[0015] S2, 5-12 parts by weight of nano-silicon dioxide and 30-80 parts by weight of 5-10 wt% hydrochloric acid are mixed, heated at 60-80°C and 100-300 rpm for 4-10 h to obtain pretreated nano-silicon dioxide; 40-70 parts by weight of methanol is added and swelled for 1-3 h, then 40-70 parts by weight of water and 1-4 parts by weight of coupling agent are added, and the mixture is reacted at 50-70°C and 300-500 rpm for 4-8 h to obtain modified nano-silicon dioxide;

[0016] S3, 3-6 parts by weight of the above indium-doped graphene oxide, 4-8 parts by weight of the above modified nano-silicon dioxide and 100-260 parts by weight of 20-40 wt% ethanol aqueous solution are mixed and stirred, and the mixture is reacted at 50-70°C and 300-500 rpm for 1-4 h to obtain a graphene-silicon dioxide composite.

[0017] The inventors found in the experiment process that the above graphene oxide and silica are connected together by an effective coupling agent, which not only effectively solves the problem of poor compatibility of traditional fillers, but also improves the surface bonding performance of graphene oxide and silica and the polyester film substrate. The indium-doped graphene oxide not only effectively increases the scratch resistance of the polyester film, but also increases the transparent conductive performance and hardness of the polyester film. The compatibility and bonding force with the polycarbonate substrate are enhanced, and the silane-modified silica promotes the combination of indium-doped graphene oxide and silica by chemical bond, enhances the intermolecular interaction between silica and graphene oxide, thereby enhancing the interfacial bonding force of the polyester film, improving the tensile strength and toughness of the film.

[0018] The graphene-silica composite not only increases the uniform dispersion of graphene oxide and silica in the functional coating liquid substrate, reduces the agglomeration phenomenon, and improves the bonding performance of the graphene-silica composite and the surface of the polyester film, but also improves the interface bonding, enhances the adhesion of the functional coating liquid, promotes stress transfer, and further improves the mechanical strength and scratch resistance of the polyester film; the indium-doped graphene oxide forms an effective reinforcing network in the film, hinders crack propagation, and further improves the scratch resistance of the film, and the silica improves the light transmission performance, reduces the interface light scattering, improves the optical uniformity, and improves the anti-glare effect.

[0019] Preferably, the coupling agent is any one of amino silane, γ-acryloxypropyl carboxyl trimethoxysilane; the amino silane is N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, (aminoethyl aminomethyl) phenethyl trimethoxysilane, 3-aminopropyl tris(methoxyethoxyethoxy) silane; further, the coupling agent is γ-acryloxypropyl carboxyl trimethoxysilane.

[0020] Carboxyl silane is a silane compound containing a carboxyl functional group, which not only binds graphene oxide and silica more firmly, but also reduces the interfacial energy and promotes uniform dispersion; the acryloxy group in γ-acryloxypropyl carboxyl trimethoxysilane exchanges with the ester group on the surface of the polyethylene terephthalate film during thermal stretching, and the carboxyl group chemically bonds with the surface of the polyester film to form a chemical crosslinking network, increase the interfacial bonding performance, and improve the mechanical properties and scratch resistance of the polyester film.

[0021] Preferably, the polyester film is any one of polyethylene terephthalate film, polytrimethylene terephthalate, polybutylene terephthalate, and polycarbonate.

[0022] Preferably, the tackifier is at least one of rosin resin, hydrogenated rosin resin, terpene resin, alkylene glycol-modified rosin ester, coumarone resin.

[0023] Preferably, the emulsifier is any one of Span-80, Tween-80, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, oleic acid diethanolamide, coconut oil fatty acid diethanolamide, maleic rosin diethanolamide.

[0024] Preferably, the curing agent is any one of methyl hexahydrophthalic anhydride, hexahydrophthalic anhydride, polyadipic anhydride, polyazelaic anhydride polyene amine, isophorone diamine, N-aminoethyl piperazine.

[0025] Preferably, the film forming agent is any one of methyl silicone oil, ethyl silicone oil, dimethyl silicone oil.

[0026] The preparation method of the polyester film for automobile screens comprises the following steps:

[0027] (1) melt-extruding the polyester base film in an extruder, the melt-extrusion temperature being 270-300 DEG C, to obtain a polyester base film melt, and then cooling the melt on a rotating cooling roller through a die to obtain a polyester base film thick sheet;

[0028] (2) coating a layer of functional coating liquid on the surface of the polyester base film thick sheet, and then introducing the polyester base film thick sheet with the functional coating liquid held by a clamp into a preheating zone for transverse stretching, and after preheating and drying at 90-120 DEG C, transversely stretching by 2.5-4 times and longitudinally stretching by 3-6 times to obtain a stretched polyester base film thick sheet;

[0029] (3) heat setting the stretched polyester base film thick sheet at a heat setting temperature of 210-240 DEG C, and then winding after cooling to obtain the polyester film for automobile screens.

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

[0031] 1. The present application provides a polyester film for automobile screens and a preparation method thereof, wherein graphene oxide and silicon dioxide composite are added in the functional coating liquid, and the mechanical properties, scratch resistance and anti-glare effect of the polyester film for automobile screens are improved through the complementary, functional synergy and interface optimization of the two-dimensional sheet structure of graphene oxide and the spherical particles of silicon dioxide.

[0032] 2. The present application realizes the all-round performance leap of the polyester film for automobile screens in terms of mechanics, optics and weather resistance, and at the same time meets the industrialization needs of environmental protection, low cost and easy processing. DETAILED DESCRIPTION

[0033] The above summary of the application will be further described in detail in conjunction with specific embodiments, but this should not be understood as limiting the scope of the above subject matter of the application to only the following examples.

[0034] In the present application, some raw materials are introduced, and other materials not introduced are all commercially available.

[0035] Polyethylene terephthalate film was purchased from Dongguan Baojia Plastic Co., Ltd., brand: 543-LBK.

[0036] Aqueous polyurethane emulsion was purchased from Shanghai Tikai Industrial Co., Ltd., model T107323.

[0037] Silicone resin was purchased from Nanjing Qinhai Trading Co., Ltd., model MPF52.

[0038] Hydrogenated rosin resin was purchased from Shandong Liang New Material Technology Co., Ltd., model LA-5G.

[0039] Coconut oil fatty acid diethanolamide was purchased from Dongying Xiwang Chemical Co., Ltd., model XW-2446.

[0040] Graphene oxide was purchased from Hubei Xiyu Hong Biological Medicine Technology Co., Ltd., item number xyh001.

[0041] The preparation method of the γ-acryloyloxypropyl carboxyl trimethoxysilane adopts the preparation method of Example 1 in patent 202410580274.6.

[0042] Nano-silicon dioxide was purchased from Qinghe County Xingxin New Material Technology Co., Ltd., particle size / number of meshes 15000 meshes.

[0043] Example 1

[0044] A polyester film for an automobile screen, comprising a polyester base film and a functional coating, the functional coating being coated on the surface of the polyester base film by a functional coating liquid; the functional coating liquid is composed of the following raw materials by weight: 25 parts by weight of aqueous polyurethane emulsion, 10 parts by weight of silicone resin, 4 parts by weight of tackifier, 3 parts by weight of emulsifier, 1 part by weight of curing agent, 2 parts by weight of film forming agent, 20 parts by weight of ethylene glycol dimethyl ether, 8 parts by weight of functional additive, 50 parts by weight of water.

[0045] The polyester base film is a polyethylene terephthalate film.

[0046] The tackifier is hydrogenated rosin resin.

[0047] The emulsifier is coconut oil fatty acid diethanolamide.

[0048] The curing agent is methyl hexahydrophthalic anhydride.

[0049] The film forming agent is methyl silicone oil.

[0050] The functional aid is a graphene-silica composite, and the preparation method of the graphene-silica composite is as follows: 4 parts by weight of graphene oxide, 6 parts by weight of nano-silica, and 150 parts by weight of 30wt% ethanol aqueous solution are mixed and stirred, and then reacted at 60℃ and 400rpm for 2h, followed by suction filtration, washing, and drying to obtain the graphene-silica composite.

[0051] The preparation method of the polyester film for automobile screens is as follows:

[0052] (1) melt-extruding the polyester base film in an extruder, with a melt-extrusion temperature of 285℃ to obtain a polyester base film melt, and then cooling the melt through a die on a rotating cooling roller to obtain a polyester base film thick sheet;

[0053] (2) coating a layer of functional coating liquid on the surface of the polyester base film thick sheet, and then introducing the polyester base film thick sheet with the functional coating liquid held by a clamp into a preheating zone for transverse stretching, followed by preheating and drying at 100℃, transverse stretching by 3.5 times, and longitudinal stretching by 4 times to obtain a stretched polyester base film thick sheet;

[0054] (3) heat-setting the stretched polyester base film thick sheet at a heat-setting temperature of 220℃, and then winding after cooling to obtain an optical polyester film for automobile screens.

[0055] Example 2

[0056] A polyester film for automobile screens, comprising a polyester base film and a functional coating layer, wherein the functional coating layer is obtained by coating a functional coating liquid on the surface of the polyester base film; the functional coating liquid is composed of the following raw materials in parts by weight: 25 parts by weight of water-based polyurethane emulsion, 10 parts by weight of silicone resin, 4 parts by weight of tackifier, 3 parts by weight of emulsifier, 1 part by weight of curing agent, 2 parts by weight of film-forming agent, 20 parts by weight of ethylene glycol dimethyl ether, 8 parts by weight of functional aid, and 50 parts by weight of water.

[0057] The polyester base film is a polyethylene terephthalate film.

[0058] The tackifier is hydrogenated rosin resin.

[0059] The emulsifier is coconut oil fatty acid diethanolamide.

[0060] The curing agent is methyl hexahydrophthalic anhydride.

[0061] The film-forming agent is methyl silicone oil.

[0062] The functional aid is a graphene-silica composite, and the preparation method of the graphene-silica composite is as follows:

[0063] S1 8 parts by weight of nano-silica and 50 parts by weight of 8wt% hydrochloric acid were mixed, heated at 70℃, 200rpm for 6h, filtered, washed, and dried to obtain pretreated nano-silica; 50 parts by weight of methanol was added and swelled for 2h, then 50 parts by weight of water and 2 parts by weight of coupling agent were added, reacted at 60℃, 400rpm for 6h, filtered, washed, and dried to obtain modified nano-silica; the coupling agent was γ-acryloyloxypropyl carboxyl trimethoxysilane;

[0064] S2, 4 parts by weight of graphene oxide, 6 parts by weight of the above modified nano-silica and 150 parts by weight of 30wt% ethanol aqueous solution were mixed and stirred, reacted at 60℃, 400rpm for 2h, suction filtered, washed, and dried to obtain graphene-silica composite.

[0065] The preparation method of the polyester film for automobile screen is as follows:

[0066] (1) The polyester base film was placed in an extruder for melt extrusion, and the melt extrusion temperature was 285℃ to obtain a polyester base film melt, and then the melt was cooled on a rotating cooling roller through a die to obtain a polyester base film thick sheet;

[0067] (2) A layer of functional coating liquid was coated on the surface of the polyester base film thick sheet, and the polyester base film thick sheet with functional coating liquid was held by a clamp and introduced into a preheating zone for transverse stretching, and after preheating and drying at 100℃, it was stretched transversely by 3.5 times and longitudinally by 4 times to obtain a stretched polyester base film thick sheet;

[0068] (3) The stretched polyester base film thick sheet was heat set at a heat setting temperature of 220℃, and after cooling, it was wound up to obtain an optical polyester film for automobile screen.

[0069] Example 3

[0070] A polyester film for automobile screen comprises a polyester base film and a functional coating layer, and the functional coating layer is obtained by coating a functional coating liquid on the surface of the polyester base film; the functional coating liquid is composed of the following raw materials in parts by weight: 25 parts by weight of water-based polyurethane emulsion, 10 parts by weight of silicone resin, 4 parts by weight of tackifier, 3 parts by weight of emulsifier, 1 part by weight of curing agent, 2 parts by weight of film-forming agent, 20 parts by weight of ethylene glycol dimethyl ether, 8 parts by weight of functional additive, and 50 parts by weight of water.

[0071] The polyester base film is a polyethylene terephthalate film.

[0072] The tackifier is hydrogenated rosin resin.

[0073] The emulsifier is coconut oil fatty acid diethanolamide.

[0074] The curing agent is methyl hexahydrophthalic anhydride.

[0075] The film-forming agent is methyl silicone oil.

[0076] The functional aid is a graphene-silica composite prepared by the following method:

[0077] S1, 5 parts by weight of graphene oxide and 100 parts by weight of 30wt% ethanol aqueous solution were mixed and ultrasonically dispersed for 1h at an ultrasonic power of 100W and an ultrasonic frequency of 40kHz, 10 parts by weight of 5wt% indium chloride aqueous solution was added, and ultrasonic dispersion was continued for 1h, then it was placed in a microwave oven at 600W for 8min, and then it was extracted, washed, and freeze-dried to obtain indium-doped graphene oxide;

[0078] S2, 4 parts by weight of the above indium-doped graphene oxide, 6 parts by weight of nano-silica, and 150 parts by weight of 30wt% ethanol aqueous solution were mixed and stirred at 60℃ and 400rpm for 2h, then it was extracted, washed, and dried to obtain a graphene-silica composite.

[0079] The preparation method of the polyester film for automobile screens is as follows:

[0080] (1) The polyester base film was placed in an extruder for melt extrusion, the melt extrusion temperature was 285℃, and the polyester base film melt was obtained, and then the melt was cooled on a rotating cooling roller through a die to obtain a polyester base film thick sheet;

[0081] (2) A layer of functional coating liquid was coated on the surface of the polyester base film thick sheet, and the polyester base film thick sheet with functional coating liquid was introduced into the preheating zone of transverse stretching by clamps, and after preheating and drying at 100℃, it was transversely stretched by 3.5 times and longitudinally stretched by 4 times to obtain a stretched polyester base film thick sheet;

[0082] (3) The stretched polyester base film thick sheet was heat set at a heat setting temperature of 220℃, and then it was wound after cooling to obtain an optical polyester film for automobile screens.

[0083] Example 4

[0084] A polyester film for automobile screens, comprising a polyester base film and a functional coating layer, the functional coating layer being obtained by coating a functional coating liquid on the surface of the polyester base film; the functional coating liquid is composed of the following raw materials in parts by weight: 25 parts by weight of water-based polyurethane emulsion, 10 parts by weight of silicone resin, 4 parts by weight of tackifier, 3 parts by weight of emulsifier, 1 part by weight of curing agent, 2 parts by weight of film-forming agent, 20 parts by weight of ethylene glycol dimethyl ether, 8 parts by weight of functional aid, and 50 parts by weight of water.

[0085] The polyester base film is a polyethylene terephthalate film.

[0086] The tackifier is hydrogenated rosin resin.

[0087] The emulsifier is coconut oil fatty acid diethanolamide.

[0088] The curing agent is methyl hexahydrophthalic anhydride.

[0089] The film forming agent is methyl silicone oil.

[0090] The functional auxiliary agent is a graphene-silica composite prepared by the following method:

[0091] S1, 5 parts by weight of graphene oxide and 100 parts by weight of 30wt% ethanol aqueous solution are mixed, ultrasonic dispersion is carried out at an ultrasonic power of 100W and an ultrasonic frequency of 40kHz for 1h, 10 parts by weight of 5wt% indium chloride aqueous solution is added, ultrasonic dispersion is continued for 1h, then it is placed in a microwave of 600W for 8min, suction filtration is carried out, washing is carried out, and freeze-drying is carried out, to obtain indium-doped graphene oxide;

[0092] S2, 8 parts by weight of nano-silica and 50 parts by weight of 8wt% hydrochloric acid are mixed, heated at 70℃ and 200rpm for 6h, filtered, washed, and dried to obtain pretreated nano-silica; 50 parts by weight of methanol is added for swelling for 2h, then 50 parts by weight of water and 2 parts by weight of a coupling agent are added, and reaction is carried out at 60℃ and 400rpm for 6h, filtration is carried out, washing is carried out, and drying is carried out, to obtain modified nano-silica; the coupling agent is γ-acryloyloxypropyl carboxyl trimethoxysilane;

[0093] S3, 4 parts by weight of the above-mentioned indium-doped graphene oxide, 6 parts by weight of the above-mentioned modified nano-silica, and 150 parts by weight of 30wt% ethanol aqueous solution are mixed and stirred, reaction is carried out at 60℃ and 400rpm for 2h, suction filtration is carried out, washing is carried out, and drying is carried out, to obtain a graphene-silica composite.

[0094] The preparation method of the polyester film for automobile screens is as follows:

[0095] (1) The polyester base film is placed in an extruder for melt extrusion, the melt extrusion temperature is 285℃, to obtain a polyester base film melt, and then the melt is cooled on a rotating cooling roller through a die, to obtain a polyester base film thick sheet;

[0096] (2) A layer of functional coating liquid is coated on the surface of the polyester base film thick sheet, the polyester base film thick sheet with the functional coating liquid is held by a clamp and introduced into a preheating zone for transverse stretching, dried after preheating at 100℃, transversely stretched by 3.5 times, and longitudinally stretched by 4 times, to obtain a stretched polyester base film thick sheet;

[0097] (3) The stretched polyester base film thick sheet is heat set at a heat setting temperature of 220℃, and after cooling, it is wound up, to obtain an optical polyester film for automobile screens.

[0098] Example 5

[0099] A polyester film for automobile screen comprises a polyester base film and a functional coating layer, which is obtained by coating a functional coating liquid on the surface of the polyester base film; the functional coating liquid is composed of the following raw materials in parts by weight: 25 parts by weight of water-based polyurethane emulsion, 10 parts by weight of silicone resin, 4 parts by weight of tackifier, 3 parts by weight of emulsifier, 1 part by weight of curing agent, 2 parts by weight of film-forming agent, 20 parts by weight of ethylene glycol dimethyl ether, 8 parts by weight of functional additive, and 50 parts by weight of water.

[0100] The polyester base film is polyethylene terephthalate film.

[0101] The tackifier is hydrogenated rosin resin.

[0102] The emulsifier is coconut oil fatty acid diethanolamide.

[0103] The curing agent is methyl hexahydrophthalic anhydride.

[0104] The film-forming agent is methyl silicone oil.

[0105] The functional additive is graphene-silica composite, and the preparation method of the graphene-silica composite is as follows:

[0106] S1, 5 parts by weight of graphene oxide and 100 parts by weight of 30wt% ethanol aqueous solution are mixed, ultrasonic dispersion is carried out at 100W ultrasonic frequency of 40kHz for 1h, 10 parts by weight of 5wt% indium chloride aqueous solution is added, ultrasonic dispersion is continued for 1h, and then it is placed in a microwave of 600W for 8min, and then it is subjected to suction filtration, washing, and freeze-drying to obtain indium-doped graphene oxide;

[0107] S2, 8 parts by weight of nano-silica and 50 parts by weight of 8wt% hydrochloric acid are mixed, heated at 70℃ and 200rpm for 6h, filtered, washed, and dried to obtain pretreated nano-silica; 50 parts by weight of methanol is added for swelling for 2h, and then 50 parts by weight of water and 2 parts by weight of coupling agent are added, and reacted at 60℃ and 400rpm for 6h, filtered, washed, and dried to obtain modified nano-silica; the coupling agent is N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane;

[0108] S3, 4 parts by weight of the above indium-doped graphene oxide, 6 parts by weight of the above modified nano-silica, and 150 parts by weight of 30wt% ethanol aqueous solution are mixed and stirred, and reacted at 60℃ and 400rpm for 2h, and then subjected to suction filtration, washing, and drying to obtain graphene-silica composite.

[0109] The preparation method of the polyester film for automobile screen is as follows:

[0110] (1) The polyester-based film is placed in an extruder for melt extrusion, and the melt extrusion temperature is 285°C to obtain a polyester-based film melt. The melt is cooled on a rotating cooling roller through a die to obtain a polyester-based film thick sheet;

[0111] (2) A functional coating liquid is coated on the surface of the polyester-based film thick sheet. The polyester-based film thick sheet with the functional coating liquid is held by a clamp and introduced into a preheating zone for transverse stretching. After preheating and drying at 100°C, the polyester-based film thick sheet is transversely stretched by 3.5 times and longitudinally stretched by 4 times to obtain a stretched polyester-based film thick sheet.

[0112] (3) The stretched polyester-based film thick sheet is heat set at a heat setting temperature of 220°C, and then wound after cooling to obtain a polyester film for automotive screens.

[0113] Test Example 1

[0114] Abrasion resistance test: The polyester film for automotive screens obtained above is tested for abrasion resistance according to the national standard GB / T 1768-2006 "Determination of Abrasion Resistance of Paint and Varnish by Rotating Rubber Wheel Method". The test is carried out at a temperature of 25°C and a relative humidity of 50%. The rotation speed of the abrasion tester is 60 r / min, and the test time is 3 min. The mass loss due to abrasion = initial test panel mass - test panel mass after test. Each group of samples is tested for 5 groups, and the average value is taken. The test results are shown in Table 1.

[0115] Table 1 Abrasion resistance test results

[0116] Wear mass loss (mg) Example 1 0.59 Example 2 0.23 Example 3 0.57 Example 4 0.03 Example 5 0.1

[0117] Test Example 2

[0118] Mechanical property evaluation: The polyester film for automotive screens prepared in each example is tested for mechanical properties according to the national standard GB / T 1040.2-2006 "Determination of Tensile Properties of Plastics - Part 3: Test Conditions for Films and Sheets". Six groups in parallel are tested, and the average value is taken. The results are shown in Table 2.

[0119] Table 2 Mechanical property test results of polyester film for automotive screens

[0120]

[0121] Test Example 3

[0122] Reflectance test: An integrating sphere is installed on a spectrophotometer to measure the reflectance of the surface of the polyester film when the BaSO4 white board is set to 100% within 400-700 nm. The average reflectance of the film with a thickness of 25 μm is calculated according to the average value. Each group of samples is tested for 5 groups, and the average value is taken. The test results are shown in Table 3.

[0123] Table 3 Reflectance test results

[0124] Reflectance (%) Example 1 9.7 Example 4 1.1 Example 5 2.3

[0125] From the above results, the optical polyester film for automobile screen prepared by the application has good mechanical properties, scratch resistance, and also has good anti-haze effect. From the above examples 1-4, by effectively coupling the graphene oxide and the silica together, the problem of poor compatibility of traditional fillers can be effectively solved, and the surface bonding performance of graphene oxide and silica with the polyester film substrate can be improved. The indium-doped graphene oxide not only effectively increases the scratch resistance of the polyester film, but also increases the transparent conductive properties and hardness of the polyester film. The compatibility and bonding force of the polyester substrate are enhanced, the silane modified silica promotes the combination of indium-doped graphene oxide and silica through chemical bond, enhances the interaction between silica and graphene oxide molecules, thereby enhancing the interface bonding force of the polyester film and improving the tensile strength and toughness of the film.

[0126] The graphene-silica composite not only increases the uniform dispersion of graphene oxide and silica in the functional coating liquid matrix, reduces the agglomeration phenomenon, and improves the bonding performance of the graphene-silica composite and the surface of the polyester film, but also improves the interface bonding, enhances the adhesion of the functional coating liquid, promotes stress transfer, and further improves the mechanical strength and scratch resistance of the polyester film; indium-doped graphene oxide forms an effective reinforcing network in the film with its excellent mechanical properties, hinders crack propagation, and further improves the scratch resistance of the film, silica improves the light transmission performance, reduces interface light scattering, improves optical uniformity, and improves the anti-glare effect.

[0127] Further comparison of examples 4-5 shows that carboxyl silane is a silane compound containing a carboxyl functional group, which not only makes the combination of graphene oxide and silica more firm, but also reduces the interface energy and promotes uniform dispersion; the acryloyloxy group in the gamma-acryloyloxypropyl carboxyl trimethoxysilane exchanges with the ester group on the surface of the polyethylene terephthalate film during thermal stretching, the carboxyl group chemically bonds with the surface of the polyester film to form a chemical crosslinking network, increase the interface bonding performance, and improve the mechanical properties and scratch resistance of the polyester film.

Claims

1. A polyester film for automotive screens comprising a polyester base film and a functional coating, characterized in that, The functional coating is obtained by coating a functional coating liquid on the surface of the polyester-based film; the functional coating liquid is composed of the following raw materials in parts by weight: 20-40 parts by weight of water-based polyurethane emulsion, 8-15 parts by weight of silicone resin, 2-6 parts by weight of tackifier, 2-4 parts by weight of emulsifier, 0.5-2 parts by weight of curing agent, 1-3 parts by weight of film-forming agent, 15-30 parts by weight of ethylene glycol dimethyl ether, 5-12 parts by weight of functional additive, 40-70 parts by weight of water, wherein the functional additive is a graphene-silica composite; and the graphene-silica composite is prepared by the following method: S1, 3-8 parts by weight of graphene oxide and 80-150 parts by weight of ethanol aqueous solution are mixed and ultrasonically dispersed, 8-15 parts by weight of 4-8 wt% indium chloride aqueous solution is added, ultrasonic dispersion is continued for 0.5-2 h, and then the mixture is placed in a microwave with a power of 400-800 W for heating for 5-10 min to obtain indium-doped graphene oxide; S2, 5-12 parts by weight of nano-silica and 30-80 parts by weight of 5-10 wt% hydrochloric acid are mixed and heated at 60-80℃ and 100-300 rpm for 4-10 h to obtain pretreated nano-silica; 40-70 parts by weight of methanol is added and swelled for 1-3 h, and then 40-70 parts by weight of water and 1-4 parts by weight of coupling agent are added and reacted at 50-70℃ and 300-500 rpm for 4-8 h to obtain modified nano-silica; S3, 3-6 parts by weight of the above indium-doped graphene oxide, 4-8 parts by weight of the above modified nano-silica and 100-260 parts by weight of 20-40 wt% ethanol aqueous solution are mixed and stirred, and reacted at 50-70℃ and 300-500 rpm for 1-4 h to obtain a graphene-silica composite.

2. The polyester film for automotive screens according to claim 1, wherein The coupling agent is any one of aminosilane, γ-acryloyloxypropylcarboxyltrimethoxysilane; the aminosilane is any one of N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, (aminoethylaminomethyl)phenethyltrimethoxysilane, 3-aminopropyltris(methoxyethoxyethoxy)silane.

3. The polyester film for automotive screens according to claim 1, wherein The polyester-based film is any one of polyethylene terephthalate film, polytrimethylene terephthalate, polybutylene terephthalate, polycarbonate.

4. The polyester film for automotive screens according to claim 1, wherein The tackifier is any one of rosin resin, hydrogenated rosin resin, terpene resin, alkylene glycol modified rosin ester, coumarone resin.

5. The polyester film for an automotive screen according to claim 1, wherein The emulsifier is any one of Span-80, Tween-80, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, oleic acid diethanolamide, coconut oil fatty acid diethanolamide, maleic rosin diethanolamide.

6. The polyester film for automotive screens according to claim 1, wherein The curing agent is any one of methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, polyadipic anhydride, polyazelaic anhydride polyene amine, isophorone diamine, N-aminoethylpiperazine.

7. The polyester film for automotive screens according to claim 1, wherein The film-forming agent is any one of methyl silicone oil, ethyl silicone oil, dimethyl silicone oil.

8. The method for producing a polyester film for an automotive screen according to any one of claims 1 to 7, characterized by, The method comprises the following steps: (1) melt-extruding the polyester-based film in an extruder, wherein the melt-extrusion temperature is 270-300℃, to obtain a polyester-based film melt, and then cooling the melt on a rotating cooling roller through a die to obtain a polyester-based film thick sheet; (2) coating a layer of functional coating liquid on the surface of the polyester-based film thick sheet, holding the polyester-based film thick sheet of the functional coating liquid with a clamp, introducing the polyester-based film thick sheet into a preheating zone of transverse stretching, preheating and drying at 90-120 DEG C, transversely stretching 2.5-4 times, longitudinally stretching 3-6 times, to obtain a stretched polyester-based film thick sheet; (3) heat setting the stretched polyester-based film thick sheet at a heat setting temperature of 210-240 DEG C, cooling and winding, to obtain the polyester film for optical use in automobile screens.

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