A modified polyester film for automotive windows and its preparation method

Abstract

This invention discloses a modified polyester film for automotive windows and its preparation method, relating to the field of polyester film technology. In preparing the modified polyester film for automotive windows, the invention first reacts methyl p-hydroxycinnamate with [chloro(ethoxy)phosphono]benzene to obtain a modified phosphorus-containing cinnamate diester compound; then reacts nano-antimony tin oxide with a silane coupling agent to obtain pre-modified nano-antimony tin oxide; the pre-modified nano-antimony tin oxide is then reacted with thiazopyridine acid, 6-maleimide-1-hexanal, and ethyl isocyanate to obtain modified nano-antimony tin oxide; terephthalic acid, ethylene glycol, the modified phosphorus-containing cinnamate diester compound, dimethyl 2,2'-difuran-5,5'-dicarboxylic acid, and the modified nano-antimony tin oxide are co-condensed to obtain a modified polyester; the modified polyester is then hot-pressed into a film to obtain the modified polyester film for automotive windows. The modified polyester film for automotive windows prepared by this invention has the advantages of flame retardancy, UV shielding, heat insulation, self-healing, and anti-aging properties.

Description

Technical Field

[0001] This invention relates to the field of polyester film technology, specifically to a modified polyester film for automotive windows and its preparation method. Background Technology

[0002] With increasing awareness of self-protection, ultraviolet (UV) protection has garnered widespread attention due to the harmful effects of UV radiation on skin and the environment in recent decades. Sunlight's UV radiation is divided into three bands: UV-C (190-280 nm), UV-B (280-320 nm), and UV-A (320-400 nm). Within these bands, UV-C is difficult to reach the Earth's surface due to atmospheric absorption. However, UV-A and UV-B radiation, which can penetrate the atmosphere, are harmful to human skin. Therefore, significant efforts have been made to eliminate or minimize the side effects of UV radiation. Consequently, many sunscreen compositions targeting UV radiation have been developed. Among these, UV absorbers have attracted considerable attention due to their high efficiency. To date, various organic UV absorbers have been reported, including benzoxazine, cinnamic acid esters, and hydroxyphenyl triazine. While these small-molecule organic UV absorbers possess excellent absorption capabilities, they also have some drawbacks, such as easy absorption by the skin and poor hydrophilicity. Furthermore, UV shielding products that simultaneously cover both UV-A and UV-B ranges are rare.

[0003] In the sweltering summer heat, almost everyone has experienced the unbearable heat of the sun radiating from under a car window. Research indicates that 50% of solar heat enters the car through the windshield; approximately 20% enters through the rear windshield; and the remaining 30% enters through the side windows. Heat transfer through glass occurs in three ways: radiation, convection, and conduction. Radiative heat transfer accounts for about 60%, conduction about 38%, and convection about 2%. Radiative heat transfer has the greatest impact on glass heat transfer; therefore, reducing radiative heat transfer is the primary way to reduce overall glass heat transfer. Furthermore, about 50% of the energy transmitted by solar radiation is concentrated in the near-infrared band with wavelengths of 780–2500 nm. Therefore, reducing radiative heat transfer through glass primarily involves reducing the transmission of near-infrared light. Summary of the Invention

[0004] The purpose of this invention is to provide a modified polyester film for automotive windows and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A modified polyester film for automotive windows, wherein the modified polyester film for automotive windows is obtained by hot pressing modified polyester into a film.

[0007] The modified polyester is prepared by copolymerization of terephthalic acid, ethylene glycol, modified phosphorus-containing cinnamic acid diester compound, 2,2'-bisfuran-5,5'-dicarboxylic acid dimethyl ester, and modified nano-tin antimony oxide.

[0008] The modified phosphorus-containing cinnamic acid diester compound is prepared by reacting methyl p-hydroxycinnamate with [chloro(ethoxy)phosphono]benzene;

[0009] The modified nano-tin antimony oxide is prepared by reacting pre-modified nano-tin antimony oxide with thiazopyridine acid, 6-maleimide-1-hexanal, and ethyl isocyanate.

[0010] The pre-modified nano-tin antimony oxide is prepared by reacting nano-tin antimony oxide with a silane coupling agent.

[0011] As an optimization, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0012] A method for preparing a modified polyester film for automotive windows includes the following preparation steps:

[0013] (1) By mass fraction, 4-5 parts of methyl p-hydroxycinnamate, 2.77-3.46 parts of triethylamine and 15-20 parts of tetrahydrofuran are mixed evenly. In an ice-water bath, at 200-300 r / min, 27.56-37.45 parts of 20wt% tetrahydrofuran solution of [chloro(ethoxy)phosphono]benzene are added at 2-3 ml / min. The reaction is carried out for 4-6 h. The mixture is filtered, the tetrahydrofuran is removed by rotary evaporation, and the mixture is recrystallized in ethanol. The mixture is then dried under vacuum at 50-60℃ for 8-10 h to obtain the modified phosphorus-containing cinnamic acid diester compound.

[0014] (2) By mass, 4-5 parts of nano-tin antimony oxide are dispersed in 25-30 parts of anhydrous ethanol, sonicated for 8-10 min, 10-12 parts of silane coupling modification solution are added and mixed evenly, stirred and refluxed at 60℃ and 300-400 r / min for 10-12 h, centrifuged for 10-12 min, the supernatant is removed, washed with anhydrous ethanol by centrifugation 3-4 times, and vacuum dried at 50-60℃ for 8-10 h to obtain pre-modified nano-tin antimony oxide;

[0015] (3) By mass fraction, 2-3 parts of pre-modified nano-tin antimony oxide, 0.45-0.62 parts of thiazopyridine acid, 0.44-0.62 parts of 6-maleimide-1-hexanal, 0.26-0.36 parts of ethyl isocyanate, and 40-50 parts of N,N-dimethylformamide are mixed evenly. At room temperature and in a closed environment, the mixture is stirred at 300-400 r / min for 24-28 h. The liquid is removed by centrifugation, and the mixture is washed 3-4 times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 50-60℃ for 8-10 h to obtain modified nano-tin antimony oxide.

[0016] (4) By mass, under an argon atmosphere, mix 2-3 parts of terephthalic acid and 0.94-1.4 parts of ethylene glycol evenly, add 0.03-0.05 parts of catalyst, react at 225-245℃, pressure 0.28-0.3MPa, 60-80r / min for 2-3h, cool to 110℃, and add 0.52-0.89 parts of modified phosphorus-containing cinnamic acid diester compound and 0.38-0.49 parts of... 2,2'-difuran-5,5'-dicarboxylic acid dimethyl ester and 0.23~0.35 parts of modified nano-tin antimony oxide were reacted at 270~280℃ under vacuum to less than 50Pa and stirred at 60~80r / min for 3~4h. The reaction was stopped when the stirrer torque reached 10N·m. The product was discharged under nitrogen protection by supercooling water, cooled and pelletized by a pelletizer, and vacuum dried at 50~60℃ for 12~16h to obtain modified polyester.

[0017] (5) Place the modified polyester in a mold, preheat at 120°C for 5 minutes, and then hot press at 150~160°C for 5~6 minutes to obtain a modified polyester film for automotive windows.

[0018] As an optimization, the reaction process of the modified phosphorus-containing cinnamic acid diester compound in step (1) is as follows:

[0019] .

[0020] As an optimization, the reaction process of the pre-modified nano-tin antimony oxide in step (2) is as follows:

[0021] .

[0022] As an optimization, the silane coupling modification solution in step (2) is prepared by mixing 1~1.2 parts of γ-aminopropyltriethoxysilane, 0.8~0.9 parts of pure water and 9~10 parts of anhydrous ethanol evenly by mass, and stirring at 200~300 r / min for 40~50 min at room temperature.

[0023] As an optimization, the reaction process for the modified nano-tin antimony oxide described in step (3) is as follows:

[0024] .

[0025] As an optimization, the catalyst in step (4) is one or a mixture of tetrabutyl titanate and antimony trioxide.

[0026] As an optimization, the structure of the 2,2'-bisfuran-5,5'-dicarboxylic acid dimethyl ester in step (4) is as follows:

[0027] .

[0028] As an optimization, the film thickness in step (5) is controlled by a mold.

[0029] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0030] In preparing the modified polyester film for automotive windows, the present invention first reacts methyl p-hydroxycinnamate with [chloro(ethoxy)phosphono]benzene to obtain a modified phosphorus-containing cinnamate diester compound; then reacts nano-antimony tin oxide with γ-aminopropyltriethoxysilane to obtain pre-modified nano-antimony tin oxide; finally, reacts the pre-modified nano-antimony tin oxide with thiazopyridine acid, 6-maleimide-1-hexanal, and ethyl isocyanate to obtain modified nano-antimony tin oxide; then, co-condenses terephthalic acid, ethylene glycol, the modified phosphorus-containing cinnamate diester compound, dimethyl 2,2'-difuran-5,5'-dicarboxylic acid, and the modified nano-antimony tin oxide to obtain a modified polyester; and finally, hot-presses the modified polyester into a film to obtain the modified polyester film for automotive windows.

[0031] First, the hydroxyl group on methyl hydroxycinnamate reacts with the phosphoryl chloride group on [chloro(ethoxy)phosphono]benzene, thereby connecting the two molecules together through a covalent bond, resulting in a compound containing phosphorus, cinnamic acid, and diester groups. The addition of phosphorus as a flame retardant element can effectively improve flame retardant performance. The cinnamic acid group has a good absorption and shielding effect on UV-B ultraviolet rays with wavelengths of 280~320nm. At the same time, the conjugated double bond on the cinnamic acid group can undergo a photoreversible dimerization reaction under the action of ultraviolet light, thus exhibiting a certain self-healing effect. The two ester groups on the molecule allow it to participate in the condensation reaction of polyester through transesterification, thereby introducing the flame retardant elements phosphorus and cinnamic acid groups into the polyester chain segment. Furthermore, the introduction of the modified phosphorus-containing cinnamic acid diester compound reduces the regularity of the polyester chain segment, thereby reducing crystallinity and improving the transmittance of visible light.

[0032] Secondly, nano-sized antimony tin oxide exhibits excellent reflectivity for near-infrared light, thereby reducing the transmission of high-energy near-infrared light and lowering radiative heat transfer, thus achieving a heat insulation effect. Simultaneously, the addition of nano-sized antimony tin oxide particles to the polyester matrix effectively prevents a decrease in visible light transmittance. To improve the dispersion of nano-antimony tin oxide, it is modified using a silane coupling agent, and amino functional groups are introduced onto its surface. Subsequently, thiazopyridine acid, 6-maleimide-1-hexanal, and ethyl isocyanate are added to conduct a Ugi multi-component reaction, introducing thiazopyridine rings onto the surface of the nano-antimony tin oxide. This results in excellent ultraviolet absorption, particularly in the 320-400nm UV-A band, where most UV absorbers have poor absorption. Combined with cinnamic acid groups, it effectively achieves complete shielding in the ultraviolet band without reducing visible light transmittance. The multi-component reaction also introduces maleimide groups, enabling it to undergo a DA reaction with furan groups.

[0033] Finally, after prepolymerization of terephthalic acid and ethylene glycol, copolymerization is carried out with modified phosphorus-containing cinnamic acid diester compound and dimethyl 2,2'-difuran-5,5'-dicarboxylic acid ester. This introduces the flame-retardant element phosphorus, cinnamic acid groups with excellent UV absorption properties, and furan groups into the polyester backbone, thereby improving the flame-retardant properties, UV absorption properties, and anti-photoaging properties of the polyester. The introduced filler-modified nano-tin antimony oxide has excellent near-infrared light reflection properties, which can reflect high-energy near-infrared light, thereby achieving a heat insulation effect. Furthermore, another UV-absorbing group, thiazolyl pyridine ring, is introduced onto the modified nano-tin antimony oxide, which can form a synergistic effect with the cinnamic acid group, thereby providing full-band shielding and absorption of the entire UV spectrum, reducing UV damage to the interior. Simultaneously, the introduced maleic acid... The imide group can undergo a DA reaction with the furan group on the polyester chain to form a covalent bond. This covalent bond is a dynamic covalent bond, which can be broken and reconnected under heating conditions, thus possessing a self-healing effect. Combined with the photodimerization effect of the cinnamic acid group, it exerts better self-healing performance, thereby effectively extending the service life. The added modified tin-antimony oxide filler is connected to the polyester main chain through the covalent bond of the DA reaction, forming a certain cross-linked structure. The nano-tin-antimony oxide itself also has a good strength improvement effect, which can effectively improve the mechanical strength of the polyester. Moreover, the cross-linked structure formed by the DA bond will break and recombine under heat, thus not affecting the processing performance. It can be repeatedly reprocessed, so after the polycondensation reaction, it can be hot-pressed into a film to produce a modified polyester film for automotive windows. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] The following information on the raw materials or preparation processes used in all the examples and comparative examples is as follows:

[0036] Nano-sized antimony tin oxide: particle size is 50nm, model number is ML-ATO-N50, purchased from Zhejiang Manli Nanotechnology Co., Ltd.

[0037] Catalyst: Tetrabutyl titanate;

[0038] Silane coupling modification solution: By mass, 1.1 parts of γ-aminopropyltriethoxysilane, 0.85 parts of pure water, and 9.5 parts of anhydrous ethanol were mixed evenly and stirred at 250 r / min for 45 min at room temperature to obtain the silane coupling modification solution.

[0039] In all the following examples and comparative examples, except for special test requirements, the thickness of the modified polyester film for automotive windows in step (5) is controlled at 150μm±10μm.

[0040] Example 1:

[0041] A method for preparing a modified polyester film for automotive windows, the method comprising the following steps:

[0042] (1) By mass fraction, 4 parts of methyl p-hydroxycinnamate, 2.77 parts of triethylamine and 15 parts of tetrahydrofuran were mixed evenly. In an ice-water bath, at 200 r / min, 27.56 parts of 20wt% tetrahydrofuran solution of [chloro(ethoxy)phosphono]benzene were added at 2 ml / min. The reaction was carried out for 6 h. The mixture was filtered, and tetrahydrofuran was removed by rotary evaporation. The mixture was recrystallized in ethanol and dried under vacuum at 50 °C for 10 h to obtain the modified phosphorus-containing cinnamic acid diester compound.

[0043] (2) By mass fraction, 4 parts of nano-tin antimony oxide were dispersed in 25 parts of anhydrous ethanol, sonicated for 8 min, 10 parts of silane coupling modification solution were added and mixed evenly, stirred and refluxed at 60℃ and 300 r / min for 12 h, centrifuged at 8000 rpm for 12 min, the supernatant was removed, washed 3 times with anhydrous ethanol by centrifugation, and vacuum dried at 50℃ for 10 h to obtain pre-modified nano-tin antimony oxide;

[0044] (3) By mass fraction, 2 parts of pre-modified nano-tin antimony oxide, 0.45 parts of thiazopyridine acid, 0.44 parts of 6-maleimide-1-hexanal, 0.26 parts of ethyl isocyanate, and 40 parts of N,N-dimethylformamide were mixed evenly. At room temperature and in a closed environment, the mixture was stirred at 300 r / min for 28 h, centrifuged at 8000 rpm for 12 min to remove the liquid, washed 3 times with anhydrous ethanol, and dried under vacuum at 50 °C for 10 h to obtain modified nano-tin antimony oxide.

[0045] (4) By mass, under an argon atmosphere, 2 parts of terephthalic acid and 0.94 parts of ethylene glycol were mixed evenly, and 0.03 parts of tetrabutyl titanate were added. The mixture was reacted at 225°C, 0.28 MPa, and 60 r / min for 3 h. The mixture was then cooled to 110°C, and 0.52 parts of modified phosphorus-containing cinnamic acid diester compound, 0.38 parts of 2,2'-bisfuran-5,5'-dicarboxylic acid dimethyl ester, and 0.23 parts of modified nano-tin antimony oxide were added. The mixture was then evacuated to less than 50 Pa at 270°C and stirred at 60 r / min for 4 h. The reaction was stopped when the stirrer torque reached 10 N·m. The mixture was discharged under nitrogen protection by supercooling water. After cooling, the mixture was pelletized by a pelletizer and dried under vacuum at 50°C for 16 h to obtain modified polyester.

[0046] (5) The modified polyester is placed in a mold, preheated at 120°C for 5 minutes and then hot-pressed at 150°C for 6 minutes to obtain a modified polyester film for automotive windows.

[0047] Example 2:

[0048] A method for preparing a modified polyester film for automotive windows, the method comprising the following steps:

[0049] (1) By mass fraction, 4.5 parts of methyl p-hydroxycinnamate, 3.12 parts of triethylamine and 18 parts of tetrahydrofuran were mixed evenly. In an ice-water bath, at 250 r / min, 31 parts of 20 wt% tetrahydrofuran solution of [chloro(ethoxy)phosphono]benzene were added at 2.5 ml / min. The reaction was carried out for 5 h. The mixture was filtered, and tetrahydrofuran was removed by rotary evaporation. The mixture was recrystallized in ethanol and dried under vacuum at 55 °C for 9 h to obtain the modified phosphorus-containing cinnamic acid diester compound.

[0050] (2) By mass fraction, 4.5 parts of nano-tin antimony oxide were dispersed in 28 parts of anhydrous ethanol, sonicated for 9 min, 11 parts of silane coupling modification solution were added and mixed evenly, and stirred and refluxed at 60℃ and 350 r / min for 11 h, centrifuged at 9000 rpm for 11 min, the supernatant was removed, and the mixture was washed 3 times with anhydrous ethanol by centrifugation, and dried under vacuum at 55℃ for 9 h to obtain pre-modified nano-tin antimony oxide;

[0051] (3) By mass fraction, 2.5 parts of pre-modified nano-tin antimony oxide, 0.54 parts of thiazopyridine acid, 0.53 parts of 6-maleimide-1-hexanal, 0.31 parts of ethyl isocyanate, and 45 parts of N,N-dimethylformamide were mixed evenly, stirred at 350 r / min for 26 h at room temperature in a closed environment, centrifuged at 9000 rpm for 11 min to remove the liquid, washed 3 times with anhydrous ethanol by centrifugation, and dried under vacuum at 55℃ for 9 h to obtain modified nano-tin antimony oxide;

[0052] (4) By mass, under an argon atmosphere, 2.5 parts of terephthalic acid and 1.17 parts of ethylene glycol were mixed evenly, and 0.04 parts of tetrabutyl titanate were added. The mixture was reacted at 235°C, 0.29 MPa, and 70 r / min for 2.5 h. The mixture was then cooled to 110°C, and 0.69 parts of modified phosphorus-containing cinnamic acid diester compound, 0.44 parts of 2,2'-bisfuran-5,5'-dicarboxylic acid dimethyl ester, and 0.29 parts of modified nano-tin antimony oxide were added. The mixture was then stirred at 70 r / min under a vacuum of less than 50 Pa at 275°C for 3.5 h. The reaction was stopped when the stirrer torque reached 10 N·m. The mixture was discharged under nitrogen protection by supercooling water, cooled, pelletized by a pelletizer, and vacuum dried at 55°C for 14 h to obtain modified polyester.

[0053] (5) The modified polyester is placed in a mold, preheated at 120°C for 5 minutes and then hot-pressed at 155°C for 6 minutes to obtain a modified polyester film for automotive windows.

[0054] Example 3:

[0055] A method for preparing a modified polyester film for automotive windows, the method comprising the following steps:

[0056] (1) By mass fraction, 5 parts of methyl p-hydroxycinnamate, 3.46 parts of triethylamine and 20 parts of tetrahydrofuran were mixed evenly. In an ice-water bath, at 300 r / min, 37.45 parts of 20wt% tetrahydrofuran solution of [chloro(ethoxy)phosphono]benzene were added at 3 ml / min. The reaction was carried out for 4 h. The mixture was filtered, and tetrahydrofuran was removed by rotary evaporation. The mixture was recrystallized in ethanol and dried under vacuum at 60 °C for 8 h to obtain the modified phosphorus-containing cinnamic acid diester compound.

[0057] (2) By mass fraction, 5 parts of nano-tin antimony oxide were dispersed in 30 parts of anhydrous ethanol, sonicated for 10 min, 12 parts of silane coupling modification solution were added and mixed evenly, and stirred and refluxed at 60℃ and 400 r / min for 10 h, centrifuged at 10000 rpm for 10 min, the supernatant was removed, and the mixture was washed 4 times with anhydrous ethanol by centrifugation, and vacuum dried at 60℃ for 8 h to obtain pre-modified nano-tin antimony oxide.

[0058] (3) By mass fraction, 3 parts of pre-modified nano-tin antimony oxide, 0.62 parts of thiazopyridine acid, 0.62 parts of 6-maleimide-1-hexanal, 0.36 parts of ethyl isocyanate and 50 parts of N,N-dimethylformamide were mixed evenly, stirred at 400 r / min for 24 h at room temperature in a closed environment, centrifuged at 10000 rpm for 10 min to remove the liquid, washed 4 times with anhydrous ethanol by centrifugation, and dried under vacuum at 60℃ for 8 h to obtain modified nano-tin antimony oxide;

[0059] (4) By mass, under an argon atmosphere, 3 parts of terephthalic acid and 1.4 parts of ethylene glycol were mixed evenly, and 0.05 parts of tetrabutyl titanate were added. The mixture was reacted at 245°C, 0.3 MPa, and 80 r / min for 2 h. The mixture was then cooled to 110°C, and 0.89 parts of modified phosphorus-containing cinnamic acid diester compound, 0.49 parts of 2,2'-bisfuran-5,5'-dicarboxylic acid dimethyl ester, and 0.35 parts of modified nano-tin antimony oxide were added. The mixture was then evacuated to less than 50 Pa at 280°C and stirred at 80 r / min for 3 h. The reaction was stopped when the stirrer torque reached 10 N·m. The mixture was discharged under nitrogen protection by supercooling water. After cooling, the mixture was pelletized by a pelletizer and dried under vacuum at 60°C for 12 h to obtain modified polyester.

[0060] (5) The modified polyester is placed in a mold, preheated at 120°C for 5 minutes and then hot-pressed at 160°C for 5 minutes to obtain a modified polyester film for automotive windows.

[0061] Comparative Example 1:

[0062] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 1 and Example 2 lies in step (2). Step (2) is modified as follows: 4.5 parts by mass of nano-tin antimony oxide are dispersed in 28 parts of anhydrous ethanol, sonicated for 9 min, and 3.75 parts of silane coupling modification solution are added and mixed evenly. The mixture is stirred and refluxed at 60°C and 350 r / min for 11 h, centrifuged at 9000 rpm for 11 min, the supernatant is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55°C for 9 h to obtain pre-modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0063] Comparative Example 2:

[0064] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 2 and Example 2 lies in step (2). Step (2) is modified as follows: 4.5 parts by mass of nano-tin antimony oxide are dispersed in 28 parts of anhydrous ethanol, sonicated for 9 min, 7.5 parts of silane coupling modification solution are added and mixed evenly. The mixture is stirred and refluxed at 60°C and 350 r / min for 11 h, centrifuged at 9000 rpm for 11 min, the supernatant is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55°C for 9 h to obtain pre-modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0065] Comparative Example 3:

[0066] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 3 and Example 2 lies in step (2). Step (2) is modified as follows: 4.5 parts by mass of nano-tin antimony oxide are dispersed in 28 parts of anhydrous ethanol, sonicated for 9 min, 15 parts of silane coupling modification solution are added and mixed evenly, and the mixture is stirred and refluxed at 60°C and 350 r / min for 11 h, centrifuged at 9000 rpm for 11 min, the supernatant is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55°C for 9 h to obtain pre-modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0067] Comparative Example 4:

[0068] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 4 and Example 2 lies in step (2). Step (2) is modified as follows: 4.5 parts by mass of nano-tin antimony oxide are dispersed in 28 parts of anhydrous ethanol, sonicated for 9 min, and 18.75 parts of silane coupling modification solution are added and mixed evenly. The mixture is stirred and refluxed at 60°C and 350 r / min for 11 h, centrifuged at 9000 rpm for 11 min, the supernatant is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55°C for 9 h to obtain pre-modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0069] Comparative Example 5:

[0070] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 5 and Example 2 lies in step (3). Step (3) is modified as follows: 2.5 parts by mass of pre-modified nano-tin antimony oxide, 0.54 parts by mass of thiazopyridine acid, 0.53 parts by mass of 6-maleimide-1-hexanal, 0.31 parts by mass of ethyl isocyanate, and 45 parts by mass of methanol are mixed evenly. The mixture is stirred at 350 r / min for 26 h at room temperature in a sealed environment, centrifuged at 9000 rpm for 11 min, the liquid is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55 °C for 9 h to obtain modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0071] Comparative Example 6:

[0072] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 6 and Example 2 lies in step (3). Step (3) is modified as follows: 2.5 parts by mass of pre-modified nano-tin antimony oxide, 0.54 parts by mass of thiazopyridine acid, 0.53 parts by mass of 6-maleimide-1-hexanal, 0.31 parts by mass of ethyl isocyanate, and 45 parts by mass of dimethyl sulfoxide are mixed evenly. The mixture is stirred at 350 r / min for 26 h at room temperature in a sealed environment, centrifuged at 9000 rpm for 11 min, the liquid is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55 °C for 9 h to obtain the modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0073] Comparative Example 7:

[0074] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 7 and Example 2 lies in step (3). Step (3) is modified as follows: 2.5 parts by mass of pre-modified nano-antimony tin oxide, 0.54 parts by mass of thiazopyridine acid, 0.53 parts by mass of 6-maleimide-1-hexanal, 0.31 parts by mass of ethyl isocyanate, and 45 parts by mass of tetrahydrofuran are mixed evenly. The mixture is stirred at 350 r / min for 26 h at room temperature in a sealed environment, centrifuged at 9000 rpm for 11 min, the liquid is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55 °C for 9 h to obtain modified nano-antimony tin oxide. The remaining steps are the same as in Example 2.

[0075] Comparative Example 8:

[0076] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 8 and Example 2 lies in step (3). Step (3) is modified as follows: 2.5 parts by mass of pre-modified nano-tin antimony oxide, 0.54 parts by mass of thiazopyridine acid, 0.53 parts by mass of 6-maleimide-1-hexanal, 0.31 parts by mass of ethyl isocyanate, and 45 parts by mass of dichloromethane are mixed evenly. The mixture is stirred at 350 r / min for 26 h at room temperature in a sealed environment, centrifuged at 9000 rpm for 11 min, the liquid is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55 °C for 9 h to obtain the modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0077] Comparative Example 9:

[0078] The preparation method of the modified polyester film for automotive windows in Comparative Example 9 differs from that in Example 2 in that step (1) is omitted, and step (4) is modified as follows: 2.82 parts by mass of terephthalic acid and 1.17 parts by mass of ethylene glycol are mixed evenly under an argon atmosphere, and 0.04 parts by mass of tetrabutyl titanate are added. The mixture is reacted at 235°C, 0.29 MPa, and 70 r / min for 2.5 h. The temperature is then lowered to 110°C, and 0.44 parts by mass of 2,2'-bisfuran-5,5'-dicarboxylic acid dimethyl ester and 0.29 parts by mass of modified nano-tin antimony oxide are added. The mixture is then stirred at 275°C under vacuum to less than 50 Pa for 3.5 h. The reaction is stopped when the stirrer torque reaches 10 N·m. The mixture is discharged under nitrogen protection by supercooling water, cooled, pelletized, and vacuum dried at 55°C for 14 h to obtain the modified polyester. The remaining steps are the same as in Example 2.

[0079] Comparative Example 10:

[0080] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 10 and Example 2 lies in step (3). Step (3) is modified as follows: 2.5 parts by mass of pre-modified nano-tin antimony oxide, 0.54 parts by mass of thiazopyridine acid, 0.29 parts by mass of benzaldehyde, 0.31 parts by mass of ethyl isocyanate, and 45 parts by mass of N,N-dimethylformamide are mixed evenly, stirred at 350 r / min for 26 h at room temperature in a sealed environment, centrifuged at 9000 rpm for 11 min to remove the liquid, washed three times with anhydrous ethanol by centrifugation, and dried under vacuum at 55 °C for 9 h to obtain modified nano-tin antimony oxide. The remaining steps are the same as in Example 2.

[0081] Comparative Example 11:

[0082] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 11 and Example 2 lies in step (3). Step (3) is modified as follows: 2.5 parts by mass of pre-modified nano-antimony tin oxide, 0.2 parts by mass of propionic acid, 0.53 parts by mass of 6-maleimide-1-hexanal, 0.31 parts by mass of ethyl isocyanate, and 45 parts by mass of N,N-dimethylformamide are mixed evenly. The mixture is stirred at 350 r / min for 26 h at room temperature in a sealed environment, centrifuged at 9000 rpm for 11 min, the liquid is removed, and the mixture is washed three times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 55 °C for 9 h to obtain the modified nano-antimony tin oxide. The remaining steps are the same as in Example 2.

[0083] Comparative Example 12:

[0084] The preparation method of the modified polyester film for automotive windows in Comparative Example 12 differs from that in Example 2 in that step (3) is omitted, and step (4) is modified as follows: by mass, under an argon atmosphere, 2.5 parts of terephthalic acid and 1.17 parts of ethylene glycol are mixed evenly, 0.04 parts of tetrabutyl titanate are added, and the mixture is reacted at 235°C, 0.29 MPa, and 70 r / min for 2.5 h. After cooling to 110°C, 0.69 parts of... Modified phosphorus-containing cinnamic acid diester compound, 0.44 parts of 2,2'-bisfuran-5,5'-dicarboxylic acid dimethyl ester, and 0.29 parts of pre-modified nano-tin antimony oxide were reacted at 275°C under vacuum to less than 50 Pa and stirred at 70 r / min for 3.5 h. The reaction was stopped when the stirrer torque reached 10 N·m. The product was discharged under nitrogen protection by supercooling water, cooled, pelletized, and vacuum dried at 55°C for 14 h to obtain modified polyester. The remaining steps were the same as in Example 2.

[0085] Comparative Example 13:

[0086] The preparation method of the modified polyester film for automotive windows in Comparative Example 13 differs from that in Example 2 in that steps (2) and (3) are omitted, and step (4) is modified as follows: 2.5 parts by mass of terephthalic acid and 1.17 parts of ethylene glycol are mixed evenly under an argon atmosphere, and 0.04 parts of tetrabutyl titanate are added. The mixture is reacted at 235°C, 0.29 MPa, and 70 r / min for 2.5 h. After cooling to 110°C, 0.69 parts of modified phosphorus-containing cinnamic acid diester compound and 0.44 parts of dimethyl 2,2'-difuran-5,5'-dicarboxylic acid are added. The mixture is stirred at 275°C under vacuum to less than 50 Pa for 3.5 h. The reaction is stopped when the stirrer torque reaches 10 N·m. The mixture is discharged under nitrogen protection by supercooling water, granulated after cooling, and vacuum dried at 55°C for 14 h to obtain the modified polyester. The remaining steps are the same as in Example 2.

[0087] Comparative Example 14:

[0088] The difference between the preparation method of the modified polyester film for automotive windows in Comparative Example 14 and Example 2 lies in step (4). Step (4) is modified as follows: 2.82 parts by mass of terephthalic acid and 1.17 parts by mass of ethylene glycol are mixed evenly under an argon atmosphere, and 0.04 parts by mass of tetrabutyl titanate are added. The mixture is reacted at 235°C, 0.29 MPa, and 70 r / min for 2.5 h. The temperature is then lowered to 110°C, and 0.69 parts by mass of modified phosphorus-containing cinnamic acid diester compound and 0.29 parts by mass of modified nano-tin antimony oxide are added. The mixture is then stirred at 275°C under vacuum to less than 50 Pa for 3.5 h. The reaction is stopped when the stirrer torque reaches 10 N·m. The mixture is discharged under nitrogen protection by supercooling water, cooled, pelletized, and vacuum dried at 55°C for 14 h to obtain the modified polyester. The remaining steps are the same as in Example 2.

[0089] Test Example 1:

[0090] Confirmation of the modification conditions for nano-tin antimony oxide (amount of silane coupling agent added, multi-component reaction solvent)

[0091] Test methods: The dispersion stability and grafting rate were analyzed. In step (2), the nano-tin antimony oxide was modified with silane coupling agent. Due to the different amounts of silane coupling agent added, the surface modification content also varied, and the stability in the dispersion also varied. Therefore, the pre-modified nano-tin antimony oxide prepared in the examples and comparative examples was dispersed in anhydrous ethanol at 4wt%. It was first stirred at 150r / min for 24h in a constant temperature water bath at 40℃, then sonicated in an ice water bath for 8min, and then centrifuged at 3000rpm for 5min. The transmittance of the supernatant was tested at 530nm. The higher the transmittance, the worse the dispersion stability and the worse the modification effect. In step (3), the multi-component reaction can provide a good reaction environment and promote a more thorough reaction. Therefore, after the reaction in step (3) was completed, it was washed according to the original steps, and then centrifuged and washed 3 times with anhydrous ethanol to ensure that the unreacted monomers were completely washed. It was then vacuum dried at 55℃ for 16h, and the grafting rate was calculated. The results are shown in Table 1.

[0092] Grafting rate: G(%) = [(M1-M0) / M0] * 100%

[0093] M0 represents the input mass of pre-modified nano-tin antimony oxide;

[0094] M1 represents the mass of the modified nano-tin antimony oxide after cleaning:

[0095]

[0096] A comparison of the experimental data from Example 2 and Comparative Examples 1-8 in Table 1 reveals that an appropriate amount of silane coupling agent should be added to achieve a good modification effect in the modification of nano-tin antimony oxide. Meanwhile, N,N-dimethylformamide is more suitable for multi-component reactions and can obtain a higher modification effect.

[0097] The comparison of data from Examples 1-4 shows that a silane coupling agent content of approximately 23%-24% of the mass of nano-tin antimony oxide is more suitable. When the amount added is less than this, the silane coupling agent dosage is too small to completely cover the surface of the modified nano-tin antimony oxide, resulting in poor modification effect, poor dispersion stability, and easier sedimentation. When the amount added is more than this, the excessive silane coupling agent causes the nano-tin antimony oxide particles to entangle and agglomerate, forming larger particles that are more likely to settle during centrifugation.

[0098] The comparison of data 5-8 shows that using N,N-dimethylformamide as a solvent can achieve better modification results. N,N-dimethylformamide has a higher boiling point and better solubility than methanol and tetrahydrofuran, resulting in a more complete reaction. In addition, the viscosity of N,N-dimethylformamide is lower than that of dimethyl sulfoxide, thus having higher mass transfer efficiency. On the other hand, dichloromethane has high reactivity and is prone to side reactions, resulting in poor modification effect.

[0099] Test Example 2:

[0100] Flame retardant performance testing: The flame retardant performance of the modified polyester film for automotive windows was evaluated using the limiting oxygen index and UL 94 flammability rating. The specific test methods are as follows: The limiting oxygen index was tested using an oxygen index instrument according to GB / T 2406.1-2008, with a sample size of 150mm×10mm×3mm; the test was conducted using a vertical-horizontal flammability tester according to ASTM D3801-2010.

[0101] The results are shown in Table 2:

[0102]

[0103] A comparison of the experimental data from Examples 1-3 and Comparative Examples 9-14 in Table 2 reveals that the modified polyester film for automotive windows prepared by this invention has excellent flame-retardant properties.

[0104] By comparing the data in the table, the data in Comparative Example 9 shows that the modified phosphorus-containing cinnamic acid diester compound introduces the flame-retardant element phosphorus into the copolymerization of polyester. The phosphorus element has good flame-retardant improvement properties and works synergistically with nano-tin antimony oxide to effectively improve the flame-retardant performance.

[0105] The data comparison in the table shows that the addition of modified nano-tin antimony oxide effectively improves the flame retardant performance of modified polyester film for automotive windows. Nano-tin antimony oxide promotes char layer formation, improves char layer stability, and reduces smoke formation, and works synergistically with the flame retardant element phosphorus, thereby effectively improving the flame retardant effect.

[0106] Test Example 3:

[0107] Mechanical properties, anti-aging properties, and self-healing properties were tested: The tensile strength, strength retention rate after UV aging, and strength recovery rate after self-healing of the prepared modified polyester film for automotive windows were tested to evaluate its mechanical properties, anti-aging properties, and self-healing properties. The test methods are as follows:

[0108] Tensile strength: The tensile strength and elongation at break of the modified polyester film for automotive windows prepared according to GB / T 1040.3-2006 were tested. The sample shape was type 5, the test speed was 50 mm / min, and each group of samples was tested in parallel 5 times. The average value was taken and the data were recorded.

[0109] UV aging strength retention rate: The modified polyester film for automotive windows was prepared into samples according to the tensile strength test method. In accordance with the standard GB / T 16422.3-2022, the samples were artificially accelerated aged for 10 days using an FR-1205-QUV ultraviolet aging tester. The tensile strength was tested again, and the strength retention rate was calculated. Each group of samples was tested 5 times, and the average value was recorded.

[0110] Self-healing strength recovery rate: The modified polyester film used for automotive windows was used to make tensile strength specimens. Scratches were cut into the middle section of the specimen surface using a scalpel. The length of the scratches was equal to the width of that part of the specimen, and the depth was about 1 mm. The specimens with scratches were kept at 120℃ for 12 hours for repair. During this period, the scratches were alternately irradiated with ultraviolet light of two different wavelengths, 365 nm and 254 nm, to promote repair. The alternation was repeated every 30 seconds. The tensile strength of the repaired specimens was tested again, and the strength recovery rate was calculated. Each group of specimens was tested 5 times, and the average value was recorded.

[0111] The results are shown in Table 3:

[0112]

[0113] A comparison of the experimental data from Examples 1-3 and Comparative Examples 9-14 in Table 3 reveals that the modified polyester film for automotive windows prepared by this invention possesses excellent mechanical properties, anti-aging properties, and self-healing properties.

[0114] The data comparison in the table shows that the addition of the modified phosphorus-containing cinnamic acid diester compound effectively improves tensile strength, anti-aging properties, and self-healing properties. The modified phosphorus-containing cinnamic acid diester compound contains cinnamic acid groups, which can undergo photodimerization under ultraviolet light to form a partial cross-linked network, thereby improving tensile strength. At the same time, due to its absorption of ultraviolet light and the existence of photoreversible dimerization, it has a certain improvement effect on anti-aging properties and self-healing properties.

[0115] By comparing the data in the table, the data in Comparative Example 10 shows that introducing maleimide groups into the modified nano-tin antimony oxide can undergo a DA reaction with the furan groups in the polyester segments to form covalent bonds and improve tensile strength. At the same time, the DA covalent bonds are dynamic and reversible covalent bonds, which can effectively improve self-healing performance.

[0116] The data comparison in the table shows that introducing a thiazolpyridine ring onto the modified nano-tin antimony oxide can effectively improve the anti-aging properties. The thiazolpyridine ring has a good absorption effect on ultraviolet rays, which can effectively alleviate the damage of ultraviolet rays to the polyester matrix.

[0117] By comparing the data in the table, the data in Comparative Example 12 shows that the Ugi multi-component reaction was successfully carried out and maleimide groups and thiazopyridine rings were introduced into the surface of the modified nano-tin antimony oxide to improve tensile strength, anti-aging properties and self-healing properties.

[0118] By comparing the data in the table, the data in Comparative Example 13 shows that the addition of modified nano-tin antimony oxide successfully improved tensile strength, anti-aging properties and self-healing properties. In addition to the functional groups introduced by modification, nano-tin antimony oxide itself, as nanoparticles, also has a good effect on improving tensile strength when it is well dispersed.

[0119] By comparing the data in the table, the data in Comparative Example 14 shows that introducing furan groups into the polyester chain segment can undergo a DA reaction with the maleimide groups on the modified nano-tin antimony oxide, thereby improving tensile strength and self-healing properties.

[0120] Test Example 4:

[0121] Optical performance testing: The ultraviolet transmittance, visible light transmittance, and near-infrared solar reflectance of the prepared modified polyester film for automotive windows were tested to evaluate its ultraviolet shielding effect, light transmission effect, and heat insulation effect. The specific test methods are as follows:

[0122] Ultraviolet and visible light transmittance: The transmittance of the modified polyester film for automotive windows was tested using a UV-3600plus UV-Vis-NIR spectrophotometer. The thickness of the modified polyester film for automotive windows was 150μm, and the test range was 280~780nm. The average transmittance of each segment was calculated. Each sample was tested 3 times, and the average value was recorded.

[0123] Near-infrared solar reflectance: The reflectance of modified polyester film for automotive windows was tested using a UV-3600plus UV-Vis-NIR spectrophotometer. The thickness of the modified polyester film for automotive windows was 150μm, and the test range was 780~2500nm. The near-infrared solar reflectance was calculated using the following formula;

[0124]

[0125] Where i(λ) is the standard solar radiation intensity, in W·m -2 ·nm -1 r(λ) is the reflectance value obtained by testing. Each group of samples was tested 3 times, and the average value was recorded.

[0126] The results are shown in Table 4:

[0127]

[0128] A comparison of the experimental data from Examples 1-3 and Comparative Examples 9-14 in Table 4 reveals that the modified polyester film for automotive windows prepared by this invention has good ultraviolet shielding rate, visible light transmittance, and heat insulation performance.

[0129] By comparing the data in the table, the data in Comparative Example 9 shows that the cinnamic acid group has a good absorption effect on ultraviolet rays in the UV-B band, which can effectively shield ultraviolet rays in this band and thus reduce the impact of ultraviolet rays.

[0130] The data comparison in the table shows that the introduction of thiazolpyridine rings into the modified nano-tin antimony oxide effectively improves the absorption of ultraviolet rays in the UV-A band, thereby forming a synergistic effect with the cinnamic acid group, thus shielding ultraviolet rays across the entire wavelength range and effectively improving the ultraviolet shielding effect.

[0131] By comparing the data in the table, the data in Comparative Example 13 shows that the addition of modified nano-tin antimony oxide not only improves the ultraviolet absorption effect, but also has a high reflectivity for sunlight in the near-infrared region, which can effectively reduce the radiative heat transfer caused by infrared light, thereby effectively improving the heat insulation effect.

[0132] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a modified polyester film for automotive windows, characterized in that, The preparation steps include the following: (1) By mass fraction, 4-5 parts of methyl p-hydroxycinnamate, 2.77-3.46 parts of triethylamine and 15-20 parts of tetrahydrofuran are mixed evenly. In an ice-water bath, at 200-300 r / min, 27.56-37.45 parts of 20wt% tetrahydrofuran solution of [chloro(ethoxy)phosphono]benzene are added at 2-3 ml / min. The reaction is carried out for 4-6 h. The mixture is filtered, the tetrahydrofuran is removed by rotary evaporation, and the mixture is recrystallized in ethanol. The mixture is then dried under vacuum at 50-60℃ for 8-10 h to obtain the modified phosphorus-containing cinnamic acid diester compound. (2) By mass, 4-5 parts of nano-tin antimony oxide are dispersed in 25-30 parts of anhydrous ethanol, sonicated for 8-10 min, 10-12 parts of silane coupling modification solution are added and mixed evenly, stirred and refluxed at 60℃ and 300-400 r / min for 10-12 h, centrifuged for 10-12 min, the supernatant is removed, washed with anhydrous ethanol by centrifugation 3-4 times, and vacuum dried at 50-60℃ for 8-10 h to obtain pre-modified nano-tin antimony oxide; (3) By mass fraction, 2-3 parts of pre-modified nano-tin antimony oxide, 0.45-0.62 parts of thiazopyridine acid, 0.44-0.62 parts of 6-maleimide-1-hexanal, 0.26-0.36 parts of ethyl isocyanate, and 40-50 parts of N,N-dimethylformamide are mixed evenly. At room temperature and in a closed environment, the mixture is stirred at 300-400 r / min for 24-28 h. The liquid is removed by centrifugation, and the mixture is washed 3-4 times with anhydrous ethanol by centrifugation. The mixture is then vacuum dried at 50-60℃ for 8-10 h to obtain modified nano-tin antimony oxide. (4) By mass, under an argon atmosphere, mix 2-3 parts of terephthalic acid and 0.94-1.4 parts of ethylene glycol evenly, add 0.03-0.05 parts of catalyst, react at 225-245℃, pressure 0.28-0.3MPa, 60-80r / min for 2-3h, cool to 110℃, and add 0.52-0.89 parts of modified phosphorus-containing cinnamic acid diester compound and 0.38-0.49 parts of... 2,2'-difuran-5,5'-dicarboxylic acid dimethyl ester and 0.23~0.35 parts of modified nano-tin antimony oxide were reacted at 270~280℃ under vacuum to less than 50Pa and stirred at 60~80r / min for 3~4h. The reaction was stopped when the stirrer torque reached 10N·m. The product was discharged under nitrogen protection by supercooling water, cooled and pelletized by a pelletizer, and vacuum dried at 50~60℃ for 12~16h to obtain modified polyester. (5) Place the modified polyester in a mold, preheat at 120°C for 5 minutes, and then hot press at 150~160°C for 5~6 minutes to obtain a modified polyester film for automotive windows. The silane coupling modification solution is prepared by mixing 1-1.2 parts by mass of γ-aminopropyltriethoxysilane, 0.8-0.9 parts by mass of pure water and 9-10 parts by mass of anhydrous ethanol, and stirring at 200-300 r / min for 40-50 min at room temperature. The structure of the [chloro(ethoxy)phosphono]benzene is as follows: ； The structure of the thiazopyridine acid is as follows: 。 2. The method for preparing a modified polyester film for automotive windows according to claim 1, characterized in that, The catalyst in step (4) is one or a mixture of tetrabutyl titanate and antimony trioxide.

3. The method for preparing a modified polyester film for automotive windows according to claim 1, characterized in that, The thickness of the modified polyester film for automotive windows in step (5) is controlled by a mold.

4. A modified polyester film for automotive windows, characterized in that, The modified polyester film for automotive windows is prepared by the method for preparing the modified polyester film for automotive windows according to any one of claims 1 to 3.

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