High-temperature-resistant release film for heat transfer printing and preparation method of high-temperature-resistant release film

Abstract

The invention discloses a high-temperature-resistant release film for heat transfer printing and a preparation method of the high-temperature-resistant release film, and relates to the technical field of high polymer materials. When the high-temperature-resistant release film for heat transfer printing is prepared, bipyridyl phenazinone and ethyl chloroacetate react to prepare pyridine cation-based phenazinone dibasic ester; the preparation method comprises the following steps: reacting tetrapod-like zinc oxide whiskers with trimethoxysilylmercaptopropyl silane to prepare sulfydryl modified zinc oxide; reacting the sulfydryl modified zinc oxide with a coumarin derivative to prepare modified zinc oxide; terephthalic acid, ethylene glycol, 1, 6-hexanediol, pyridine cation-based phenazinone dibasic ester, dihydroxy DOPO and modified zinc oxide are subjected to a reaction and polycondensation, and then pelletizing, extrusion and stretching film forming are performed to prepare a modified polyester film; and coating the modified polyester film with the release agent to prepare the high-temperature-resistant release film for heat transfer printing. The high-temperature-resistant release film for heat transfer printing has the advantages of aging resistance, high temperature resistance, flame retardance, static resistance and good tensile strength.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a high-temperature resistant release film for thermal transfer and a preparation method thereof. Background Art

[0002] Thermal transfer is a type of transfer printing, and its essence is a process of transferring patterns or texts on a thermal transfer film onto a substrate through the action of heat and pressure. A thermal transfer release film is a special functional printing film made by coating a release agent on the surface of a carrier film.

[0003] As a carrier film, it requires good high-temperature resistance and high tensile strength. Commonly used materials include polyvinyl chloride, polyethylene, polyethylene terephthalate, etc. The most widely used is polyethylene terephthalate. Although polyethylene terephthalate is widely used, due to the insulating properties of the material itself, static charges are easily generated and accumulated during use due to contact and friction, and its surface resistivity is as high as 10 16 Ω, and it is more likely to accumulate static charges in low-humidity environments. The static electricity problem brings many troubles to the processing and application of polyethylene terephthalate. Due to the existence of static charges, the surface of polyethylene terephthalate products is easily adsorbed with dust during storage and use, affecting the appearance; when processing polyethylene terephthalate products with a large surface area such as films, the force generated by static charges greatly interferes with the processing process and hinders the winding of the film; in the application of polyethylene terephthalate in electronic and electrical products, when the static charge capacity reaches a certain value, it will also cause unsafe accidents due to discharge.

[0004] Therefore, in order to improve the application safety and processing performance of polyethylene terephthalate, it is necessary to improve the antistatic performance. At the same time, as a thermal transfer film, a polyethylene terephthalate film with excellent antistatic performance can avoid dust adsorption during the thermal transfer process and effectively improve the qualification rate. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-temperature resistant release film for thermal transfer and a preparation method thereof to solve the problems existing in the prior art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A high-temperature resistant release film for thermal transfer, wherein the high-temperature resistant release film for thermal transfer is obtained by coating a release agent on a modified polyester film;

[0008] The modified polyester film is obtained by reacting terephthalic acid, ethylene glycol, 1,6-hexanediol, pyridinium cationic phenazinone diester, dihydroxy DOPO, and modified zinc oxide, cutting into pellets, extruding, and stretching into a film.

[0009] The pyridinium cation-based phenazinone diester is prepared by reacting bispyridyl phenazinone with ethyl chloroacetate;

[0010] The bispyridyl phenazinone is prepared by reacting 4-isocyanatopyridine with 4-(4-pyridylmethyl)-1(2H)-phthalazinone;

[0011] The modified zinc oxide is prepared by reacting mercapto-modified zinc oxide with a coumarin derivative;

[0012] The mercapto-modified zinc oxide is prepared by reacting tetrapod-shaped zinc oxide whiskers with 3-mercaptopropyltrimethoxysilane.

[0013] As an optimization, the coumarin derivative is 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin.

[0014] As an optimization, the dihydroxy DOPO is 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, and the CAS number is 99208-50-1.

[0015] As an optimization, the release agent is one of a silicone-based release agent, a fluorosilicone-based release agent, and a polytetrafluoroethylene-based release agent.

[0016] As an optimization, the surface resistivity of the tetrapod-shaped zinc oxide whiskers is less than 10 4 Ω.

[0017] A preparation method of a high-temperature resistant release film for thermal transfer includes the following preparation steps:

[0018] (1) Under a nitrogen atmosphere, 4-isocyanatopyridine and N,N-dimethylformamide are mixed and stirred, 4-(4-pyridylmethyl)-1(2H)-phthalazinone is added, stirring is continued, and dibutyltin dilaurate is added while heating to carry out a stirring reaction, followed by cooling, rotary evaporation, and drying to obtain bispyridyl phenazinone;

[0019] (2) Bispyridyl phenazinone and N,N-dimethylformamide are mixed, ethyl chloroacetate is added, a reaction is carried out, precipitation is carried out in acetone, suction filtration, washing, and drying are carried out to obtain the pyridinium cation-based phenazinone diester;

[0020] (3) Absolute ethanol, pure water, and tetrapod-shaped zinc oxide whiskers are mixed, ultrasonic treatment is carried out, 3-mercaptopropyltrimethoxysilane is added, the pH is adjusted, heating and reflux reaction are carried out, suction filtration, washing, and drying are carried out to obtain mercapto-modified zinc oxide;

[0021] (4) Mix 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin, mercapto-modified zinc oxide, and tetrahydrofuran, stir, add azobisisobutyronitrile, heat and stir under reflux, filter by suction, wash, and dry to obtain modified zinc oxide;

[0022] (5) Mix terephthalic acid, ethylene glycol, 1,6-hexanediol, pyridinium cationic phenazinone diester, and tetrabutyl titanate. Under a nitrogen atmosphere, seal the reaction kettle, heat and pressurize the reaction until 98% of the theoretical value of the esterification water stock is reached, relieve the pressure and transfer it to the polycondensation kettle. Then add dihydroxy DOPO and modified zinc oxide, heat, evacuate, stir and react until the viscosity increases and the Weissenberg effect appears, stop the reaction, fill with nitrogen to relieve the vacuum, pressurize and extrude from the reaction kettle, pelletize, add to the twin-screw extruder and extrude and stretch into a film to obtain a modified polyester film;

[0023] (6) Coat the release agent on the modified polyester film and place it in a vacuum oven at 80-90 °C for 4-5 h to obtain a high-temperature resistant release film for thermal transfer.

[0024] As an optimization, the dipyridyl phenazinone in step (1) is prepared by mixing 2-3 parts of 4-isocyanatopyridine and 12-15 parts of N,N-dimethylformamide evenly under a nitrogen atmosphere at room temperature, stirring at 300-400 r / min for 30-40 min, adding 3.95-5.93 parts of 4-(4-pyridylmethyl)-1(2H)-phthalazinone, continuing to stir for 20-30 min, then heating to 105-110 °C, adding 0.009-0.013 parts of dibutyltin dilaurate, stirring and reacting at 400-500 r / min for 4-5 h, naturally cooling to room temperature, rotary evaporating to remove the solvent, and vacuum drying at 50-60 °C for 10-12 h.

[0025] As an optimization, the reaction process of the dipyridyl phenazinone in step (1) is as follows:

[0026] 。

[0027] As an optimization, the pyridinium cationic phenazinone diester in step (2) is prepared by mixing 2-3 parts of dipyridyl phenazinone and 12-15 parts of N,N-dimethylformamide evenly by mass, adding 1.51-2.37 parts of ethyl chloroacetate, reacting at 60-65 °C and 300-400 r / min for 22-24 h, precipitating in 20-25 parts of acetone for 50-60 min, filtering by suction, washing with absolute ethanol 3-4 times, and vacuum drying at 50-60 °C for 10-12 h.

[0028] As an optimization, the reaction process of the pyridinium cationic phenazinone diester in step (2) is as follows:

[0029] .

[0030] As an optimization, the mercapto-modified zinc oxide described in step (3) is prepared by mixing 10-12 parts by mass of absolute ethanol, 1-1.2 parts by mass of pure water, and 0.4-0.5 parts by mass of tetrapod-shaped zinc oxide whiskers evenly, ultrasonicating at 40 °C for 30-35 min, adding 0.5-0.7 parts by mass of mercaptopropyltrimethoxysilane, adjusting the pH to 8-9 with 6 mol / L ammonia water, refluxing and reacting at 80 °C at 300-400 r / min for 8-10 h, filtering by suction, washing 3-4 times with absolute ethanol, and drying in vacuum at 50-60 °C for 8-10 h.

[0031] As an optimization, the reaction process of the mercapto-modified zinc oxide described in step (3) is as follows:

[0032] .

[0033] As an optimization, the modified zinc oxide described in step (4) is prepared by mixing 1-1.5 parts by mass of 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin, 1-1.2 parts by mass of mercapto-modified zinc oxide, and 10-12 parts by mass of tetrahydrofuran evenly, stirring at 400-500 r / min for 30-40 min, adding 0.01-0.012 parts by mass of azobisisobutyronitrile, stirring and refluxing at 75-80 °C at 400-500 r / min for 8-10 h, filtering by suction, washing 3-4 times alternately with absolute ethanol and pure water, and drying in vacuum at 40-50 °C for 10-12 h.

[0034] As an optimization, the reaction process of the modified zinc oxide described in step (4) is as follows:

[0035] .

[0036] As an optimization, the modified polyester film described in step (5) is prepared by uniformly mixing 3-4 parts by mass of terephthalic acid, 0.48-0.57 parts of ethylene glycol, 0.97-1.38 parts of 1,6-hexanediol, 1.18-1.57 parts of pyridinium cationic phenazinone diester, and 0.03-0.05 parts of tetrabutyl titanate. Under a nitrogen atmosphere, the reaction kettle is sealed, and at 230-250 °C, a pressure of 0.3-0.4 MPa, a steam top temperature of 120-150 °C, and stirring at 40-50 r / min until 98% of the theoretical value of the esterification water stock is reached. Then, the pressure is released and transferred to a polycondensation kettle, and 1.14-1.69 parts of dihydroxy DOPO and 1.69-2.26 parts of modified zinc oxide are added. At 250-270 °C, the vacuum is pumped to a vacuum degree less than 50 Pa, and stirring at 70-80 r / min until the Weissenberg effect appears due to the increase in viscosity, then the reaction is stopped, nitrogen is filled to relieve the vacuum, the reaction kettle is pressurized to extrude, pelletized, added to a twin-screw extruder, and extruded at 270-280 °C and 80-100 rpm and then biaxially stretched into a film.

[0037] As an optimization, the coating thickness of the coating described in step (6) is 5-6 μm.

[0038] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0039] When preparing the high-temperature resistant release film for thermal transfer, the present invention first reacts 4-isocyanatopyridine with 4-(4-pyridylmethyl)-1(2H)-phthalazinone to obtain bipyridyl phenazinone; reacts bipyridyl phenazinone with ethyl chloroacetate to obtain pyridinium cationic phenazinone diester; reacts tetrapod-like zinc oxide whiskers with 3-mercaptopropyltrimethoxysilane to obtain mercapto-modified zinc oxide; reacts mercapto-modified zinc oxide with coumarin derivatives to obtain modified zinc oxide; reacts terephthalic acid, ethylene glycol, 1,6-hexanediol, pyridinium cationic phenazinone diester, dihydroxy DOPO, and modified zinc oxide, then pelletizes, extrudes, and stretches into a film to obtain a modified polyester film; and coats a release agent on the modified polyester film to obtain the high-temperature resistant release film for thermal transfer.

[0040] First, the isocyanate group on 4-isocyanatopyridine reacts with the amino proton on the lactam ring of 4-(4-pyridylmethyl)-1(2H)-phthalazinone, thereby introducing a bipyridine group. As a phthalazinone structure, phenazinone has a unique twisted and non-coplanar structure, and this special structure endows it with excellent thermal stability and mechanical properties. Introducing it into the high-temperature resistant release film for thermal transfer can effectively improve the high-temperature resistance and mechanical properties. Subsequently, the chlorine atom on ethyl chloroacetate undergoes a quaternization reaction with the pyridine group in bipyridyl phenazinone, thereby preparing pyridinium cationic phenazinone diester, which contains two ester groups, enabling it to enter the polyester main chain through transesterification reaction during the polycondensation reaction of polyester. Pyridinium cationic phenazinone diester also introduces pyridinium cations through quaternization reaction. The introduction of cations improves the conductivity, reduces the resistivity, and thus improves the antistatic performance.

[0041] Secondly, tetrapod-like zinc oxide whiskers have good electrical conductivity, and they can greatly improve the electrical conductivity of the matrix through tip discharge and network conduction. They can form a three-dimensional network conductive path and an effective three-dimensional conductive network. At the same time, tetrapod-like zinc oxide whiskers have good absorption effects in the ultraviolet band and can effectively improve the anti-aging performance. Using mercaptopropyltrimethoxysilane to modify tetrapod-like zinc oxide whiskers to obtain mercapto-modified zinc oxide can effectively improve the dispersion ability of tetrapod-like zinc oxide whiskers in the matrix and avoid agglomeration, which may lead to performance degradation. This step of modification introduces mercapto reactive groups onto tetrapod-like zinc oxide whiskers. Subsequently, 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin, a coumarin derivative containing double bonds and hydroxyl groups, is used to further modify mercapto-modified zinc oxide to obtain modified zinc oxide. The mercapto group on mercapto-modified zinc oxide undergoes a click reaction with the double bond on the coumarin derivative, thereby introducing the coumarin derivative onto mercapto-modified zinc oxide. The modified modified zinc oxide is introduced with thioether groups and coumarin groups. Thioether groups have good antioxidant auxiliary effects, and coumarin groups also have ultraviolet absorption ability. Zinc oxide, coumarin groups, and thioether groups play a good anti-aging role through synergistic effects, and reactive hydroxyl groups are introduced. During the polycondensation process, they can be connected to the matrix through esterification or transesterification reactions with carboxylic acids and ester groups. The covalent bond connection further improves the fixing effect of modified zinc oxide, avoids the decrease in antistatic ability caused by the migration of modified zinc oxide in the matrix, and simultaneously improves and enhances the tensile strength.

[0042] Finally, terephthalic acid, ethylene glycol, 1,6 - hexanediol, pyridinium cationic phenazinone diester, dihydroxy DOPO, and modified zinc oxide are reacted and then pelletized, extruded, and stretched into a film to obtain a modified polyester film. In addition to the basic raw materials terephthalic acid and ethylene glycol, the modified polyester film incorporates modified pyridinium cationic phenazinone diester, modified zinc oxide, and dihydroxy DOPO. The pyridinium cationic phenazinone diester enters the polyester matrix through transesterification reaction, which can effectively improve the high - temperature resistance, tensile strength, and antistatic properties. The modified zinc oxide is added as a metal particle filler, and the modified hydroxyl groups on it enable it to be fixed in the polyester network through covalent bond action, effectively improving the tensile strength. Its good conductivity and unique microstructure can effectively improve the antistatic properties, and its ultraviolet absorption ability, synergistic assistance with sulfide groups and coumarin groups also effectively improve the anti - aging ability. Dihydroxy DOPO enters the main chain of the polyester through esterification polycondensation reaction. The unique rigid structure of DOPO can improve the tensile strength of the matrix. The introduction of dihydroxy DOPO also introduces the flame - retardant element phosphorus and improves the flame - retardant performance. A release agent is coated on the modified polyester film to obtain a high - temperature - resistant release film for thermal transfer. Detailed implementation mode

[0043] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0044] The release agent used in all the following examples and comparative examples is a fluorine - based release agent, model Q2 - 7785, purchased from Shanghai Mingxu Electronic Technology Co., Ltd.

[0045] The surface resistivity of the tetrapod - shaped zinc oxide whiskers used in all the following examples and comparative examples is between 10 3 ~10 4 Ω, purchased from Chengdu Jiaotong Jingyu Technology Co., Ltd.

[0046] Example 1:

[0047] A preparation method of a high - temperature - resistant release film for thermal transfer, the preparation method of the high - temperature - resistant release film for thermal transfer includes the following preparation steps:

[0048] (1)Under a nitrogen atmosphere, 2 parts by mass of 4-isocyanatopyridine and 12 parts by mass of N,N-dimethylformamide were mixed evenly. At room temperature, they were stirred at 300 r / min for 40 min. Then, 3.95 parts by mass of 4-(4-pyridylmethyl)-1(2H)-phthalazinone was added, and stirring continued for 30 min. Subsequently, the temperature was raised to 105 °C, and 0.009 parts by mass of dibutyltin dilaurate was added. The reaction was carried out by stirring at 400 r / min for 5 h. It was naturally cooled to room temperature, the solvent was removed by rotary evaporation, and it was dried in vacuo at 50 °C for 12 h to obtain bispyridylphthalazinone.

[0049] (2)2 parts by mass of bispyridylphthalazinone and 12 parts by mass of N,N-dimethylformamide were mixed evenly. 1.51 parts by mass of ethyl chloroacetate was added, and the reaction was carried out at 60 °C and 300 r / min for 24 h. It was precipitated in 20 parts by mass of acetone for 60 min, filtered by suction, washed 3 times with absolute ethanol, and dried in vacuo at 50 °C for 12 h to obtain pyridinium cationic phthalazinone diester.

[0050] (3)10 parts by mass of absolute ethanol, 1 part by mass of pure water, and 0.4 part by mass of tetrapod-shaped zinc oxide whiskers were mixed evenly. At 40 °C, ultrasonic treatment was carried out for 30 min. 0.5 part by mass of mercaptopropyltrimethoxysilane was added, and the pH was adjusted to 8 with 6 mol / L ammonia water. The reflux reaction was carried out at 80 °C and 300 r / min for 10 h. It was filtered by suction, washed 3 times with absolute ethanol, and dried in vacuo at 50 °C for 10 h to obtain mercapto-modified zinc oxide.

[0051] (4)1 part by mass of 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin, 1 part by mass of mercapto-modified zinc oxide, and 10 parts by mass of tetrahydrofuran were mixed evenly. They were stirred at 400 r / min for 40 min. 0.01 part by mass of azobisisobutyronitrile was added, and the stirring reflux reaction was carried out at 75 °C and 400 r / min for 10 h. It was filtered by suction, washed 3 times alternately with absolute ethanol and pure water, and dried in vacuo at 40 °C for 12 h to obtain modified zinc oxide.

[0052] (5) Mix 3 parts of terephthalic acid, 0.48 parts of ethylene glycol, 0.97 parts of 1,6 - hexanediol, 1.18 parts of pyridinium cationic phenazinone diester, and 0.03 parts of tetrabutyl titanate evenly by mass. Under a nitrogen atmosphere, seal the reaction kettle. At 230 °C, with a pressure of 0.3 MPa and a steam top temperature of 120 °C, stir and react at 40 r / min until 98% of the theoretical value of the esterification water stock is reached. Release the pressure and transfer it to the polycondensation kettle. Then add 1.14 parts of dihydroxy DOPO and 1.69 parts of modified zinc oxide. At 250 °C, evacuate to a vacuum degree less than 50 Pa, stir and react at 70 r / min until the viscosity increases and the Weissenberg effect appears. Stop the reaction, fill with nitrogen to relieve the vacuum, pressurize and extrude from the reaction kettle, pelletize, add it to a twin - screw extruder, and extrude at 270 °C and 80 rpm, then biaxially stretch to form a film to obtain a modified polyester film;

[0053] (6) Coat the release agent on the modified polyester film and place it in a vacuum oven at 80 °C for 5 h to obtain a high - temperature resistant release film for thermal transfer.

[0054] Example 2:

[0055] A preparation method of a high - temperature resistant release film for thermal transfer, the preparation method of the high - temperature resistant release film for thermal transfer includes the following preparation steps:

[0056] (1) Under a nitrogen atmosphere, mix 2.5 parts of 4 - isocyanatopyridine and 13.5 parts of N,N - dimethylformamide evenly by mass. At room temperature, stir at 350 r / min for 35 min, add 4.94 parts of 4 - (4 - pyridylmethyl) - 1(2H) - phthalazinone, continue to stir for 25 min, then raise the temperature to 108 °C, add 0.011 parts of dibutyltin dilaurate, stir and react at 450 r / min for 4.5 h, naturally cool to room temperature, remove the solvent by rotary evaporation, and vacuum dry at 55 °C for 11 h to obtain bipyridyl phenazinone;

[0057] (2) Mix 2.5 parts of bipyridyl phenazinone and 13.5 parts of N,N - dimethylformamide evenly by mass, add 1.93 parts of ethyl chloroacetate, react at 60 °C and 350 r / min for 23 h, precipitate in 22 parts of acetone for 55 min, filter, wash with absolute ethanol 3 times, and vacuum dry at 55 °C for 11 h to obtain pyridinium cationic phenazinone diester;

[0058] (3) Mix 11 parts of absolute ethanol, 1.1 parts of pure water, and 0.45 parts of tetrapod - shaped zinc oxide whiskers evenly. At 40 °C, sonicate for 32 min, add 0.6 parts of mercaptopropyltrimethoxysilane, adjust the pH to 8.5 with 6 mol / L ammonia water, reflux and react at 80 °C and 350 r / min for 9 h, filter, wash with absolute ethanol 3 times, and vacuum dry at 55 °C for 9 h to obtain mercapto - modified zinc oxide;

[0059] (4) By weight, 1.2 parts of 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin, 1.1 parts of mercapto-modified zinc oxide, and 11 parts of tetrahydrofuran were mixed evenly, stirred at 450 r / min for 35 min, 0.011 parts of azobisisobutyronitrile were added, and the mixture was stirred and refluxed at 78°C and 450 r / min for 9 h. The mixture was filtered, washed alternately with anhydrous ethanol and pure water for 3 times, and dried in vacuo at 45°C for 11 h to obtain modified zinc oxide.

[0060] (5) According to the mass fraction, 3.5 parts of terephthalic acid, 0.53 parts of ethylene glycol, 1.17 parts of 1,6-hexanediol, 1.37 parts of pyridinium cationic phenol ketone dibasic ester and 0.04 parts of tetrabutyl titanate were mixed evenly. Under nitrogen atmosphere, the reactor was sealed and stirred at 240℃, 0.35MPa and 135℃ steam tower top temperature, and the mixture was reacted at 45r / min until the esterification water content reached 98% of the theoretical value. The mixture was depressurized and transferred to a polycondensation reactor. 1.4 parts of dihydroxy DOPO and 1.97 parts of modified zinc oxide were added. The mixture was evacuated at 260℃ until the vacuum degree was less than 50Pa. The mixture was stirred at 75r / min until the viscosity increased and the Weisenberg effect appeared. The reaction was stopped, nitrogen was added to release the vacuum, the mixture was pressed out of the reactor, pelletized, added to a twin-screw extruder, extruded at 275℃ and 90rpm, and biaxially stretched into a film to obtain a modified polyester film.

[0061] (6) The release agent was coated on the modified polyester film and placed in a vacuum oven at 85°C for 4.5 hours to obtain a high-temperature resistant release film for thermal transfer.

[0062] Example 3:

[0063] A method for preparing a high-temperature resistant release film for thermal transfer, the method comprising the following steps:

[0064] (1) Under nitrogen atmosphere, 3 parts of 4-isocyanate pyridine and 15 parts of N,N-dimethylformamide were mixed uniformly by mass, stirred at 400 r / min at room temperature for 30 min, 5.93 parts of 4-(4-pyridylmethyl)-1(2H)-phthalazinone were added, and stirring was continued for 30 min. The temperature was then raised to 110°C, 0.013 parts of dibutyltin dilaurate were added, and the mixture was stirred at 500 r / min for 4 h. The mixture was naturally cooled to room temperature, the solvent was removed by rotary evaporation, and vacuum dried at 60°C for 10 h to obtain bispyridylphenolazinone;

[0065] (2) By mass fraction, 3 parts of dipyridylphenazine ketone and 15 parts of N,N-dimethylformamide were mixed evenly, 2.37 parts of ethyl chloroacetate were added, and the reaction was carried out at 65 °C and 400 r / min for 22 h. It was precipitated in 25 parts of acetone for 50 min, filtered by suction, washed 4 times with absolute ethanol, and vacuum dried at 60 °C for 10 h to obtain pyridinium cationic phenazine ketone diester;

[0066] (3) By mass fraction, 12 parts of absolute ethanol, 1.2 parts of pure water, and 0.5 part of tetrapod-like zinc oxide whiskers were mixed evenly, ultrasonicated at 40 °C for 35 min, 0.7 part of mercaptopropyltrimethoxysilane was added, and the pH was adjusted to 9 with 6 mol / L ammonia water. The reflux reaction was carried out at 80 °C and 400 r / min for 8 h, filtered by suction, washed 4 times with absolute ethanol, and vacuum dried at 60 °C for 8 h to obtain mercapto-modified zinc oxide;

[0067] (4) By mass fraction, 1.5 parts of 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin, 1.2 parts of mercapto-modified zinc oxide, and 12 parts of tetrahydrofuran were mixed evenly, stirred at 500 r / min for 30 min, 0.012 part of azobisisobutyronitrile was added, and the stirring reflux reaction was carried out at 80 °C and 500 r / min for 8 h. Filtered by suction, washed 4 times alternately with absolute ethanol and pure water, and vacuum dried at 50 °C for 10 h to obtain modified zinc oxide;

[0068] (5) By mass fraction, 4 parts of terephthalic acid, 0.57 part of ethylene glycol, 1.38 parts of 1,6-hexanediol, 1.57 parts of pyridinium cationic phenazine ketone diester, and 0.05 part of tetrabutyl titanate were mixed evenly. Under a nitrogen atmosphere, the reaction kettle was sealed, and the reaction was carried out at 250 °C, a pressure of 0.4 MPa, and a steam top temperature of 150 °C, with stirring at 50 r / min until 98% of the theoretical value of the esterification water stock was reached. The pressure was relieved and transferred to the polycondensation kettle. Then, 1.69 parts of dihydroxy DOPO and 2.26 parts of modified zinc oxide were added. At 270 °C, the vacuum was pumped to a vacuum degree of less than 50 Pa, and the stirring reaction was carried out at 80 r / min until the viscosity increased and the Weissenberg effect appeared. The reaction was stopped, nitrogen was filled to relieve the vacuum, and the reaction kettle was pressurized to extrude the product, pelletized, added to a twin-screw extruder, and extruded at 280 °C and 100 rpm and then biaxially stretched into a film to obtain a modified polyester film;

[0069] (6) The release agent was coated on the modified polyester film and placed in a vacuum oven at 90 °C for 4 h to obtain a high-temperature resistant release film for thermal transfer.

[0070] Comparative Example 1:

[0071] The preparation method of the high-temperature resistant release film for thermal transfer of Comparative Example 1 is different from that of Example 2 in that step (2) is not carried out, and step (5) is modified as follows: by mass, 3.5 parts of terephthalic acid, 0.53 parts of ethylene glycol, 1.17 parts of 1,6-hexanediol, 1.37 parts of dipyridylphenazine ketone, and 0.04 parts of tetrabutyl titanate are mixed evenly. Under a nitrogen atmosphere, the reaction kettle is sealed. At 240 °C, with a pressure of 0.35 MPa and a steam top temperature of 135 °C, stirring reaction is carried out at 45 r / min until 98% of the theoretical value of the esterification water stock is reached. The pressure is released and transferred to a polycondensation kettle, and then 1.4 parts of dihydroxy DOPO and 1.97 parts of modified zinc oxide are added. At 260 °C, the vacuum is pumped to a vacuum degree of less than 50 Pa, and stirring reaction is carried out at 75 r / min until the viscosity increases and the Weissenberg effect appears, then the reaction is stopped. Nitrogen is filled to relieve the vacuum, and the pressure is applied to press out of the reaction kettle, pelletized, added to a twin-screw extruder, and extruded at 275 °C and 90 rpm and then biaxially stretched into a film to obtain a modified polyester film. The remaining steps are the same as those of Example 2.

[0072] Comparative Example 2:

[0073] The preparation method of the high-temperature resistant release film for thermal transfer of Comparative Example 2 is different from that of Example 2 in that steps (1) and (2) are not carried out, and step (5) is modified as follows: by mass, 3.5 parts of terephthalic acid, 0.48 parts of ethylene glycol, 1.06 parts of 1,6-hexanediol, and 0.04 parts of tetrabutyl titanate are mixed evenly. Under a nitrogen atmosphere, the reaction kettle is sealed. At 240 °C, with a pressure of 0.35 MPa and a steam top temperature of 135 °C, stirring reaction is carried out at 45 r / min until 98% of the theoretical value of the esterification water stock is reached. The pressure is released and transferred to a polycondensation kettle, and then 1.27 parts of dihydroxy DOPO and 1.58 parts of modified zinc oxide are added. At 260 °C, the vacuum is pumped to a vacuum degree of less than 50 Pa, and stirring reaction is carried out at 75 r / min until the viscosity increases and the Weissenberg effect appears, then the reaction is stopped. Nitrogen is filled to relieve the vacuum, and the pressure is applied to press out of the reaction kettle, pelletized, added to a twin-screw extruder, and extruded at 275 °C and 90 rpm and then biaxially stretched into a film to obtain a modified polyester film. The remaining steps are the same as those of Example 2.

[0074] Comparative Example 3:

[0075] The preparation method of the high-temperature resistant release film for thermal transfer in Comparative Example 3 is different from that in Example 2 in that step (4) is not carried out, and step (5) is modified as follows: by mass, 3.5 parts of terephthalic acid, 0.53 parts of ethylene glycol, 1.17 parts of 1,6-hexanediol, 1.37 parts of pyridinium cationic phenazine ketone diester, and 0.04 parts of tetrabutyl titanate are mixed evenly. Under a nitrogen atmosphere, the reaction kettle is sealed. At 240 °C, with a pressure of 0.35 MPa and a steam top temperature of 135 °C, the mixture is stirred and reacted at 45 r / min until 98% of the theoretical value of the esterification water stock is reached. The pressure is released and the mixture is transferred to a polycondensation kettle. Then, 1.4 parts of dihydroxy DOPO and 1.97 parts of mercapto-modified zinc oxide are added. At 260 °C, the vacuum is pumped to a vacuum degree of less than 50 Pa, and the mixture is stirred and reacted at 75 r / min until the viscosity increases and the Weissenberg effect appears. The reaction is stopped, nitrogen is filled to relieve the vacuum, the reaction kettle is pressurized and extruded, pelletized, added to a twin-screw extruder, extruded at 275 °C and 90 rpm, and then biaxially stretched into a film to obtain a modified polyester film. The remaining steps are the same as those in Example 2.

[0076] Comparative Example 4:

[0077] The preparation method of the high-temperature resistant release film for thermal transfer in Comparative Example 4 is different from that in Example 2 in that steps (3) and (4) are not carried out, and step (5) is modified as follows: by mass, 3.5 parts of terephthalic acid, 0.53 parts of ethylene glycol, 1.17 parts of 1,6-hexanediol, 1.37 parts of pyridinium cationic phenazine ketone diester, and 0.04 parts of tetrabutyl titanate are mixed evenly. Under a nitrogen atmosphere, the reaction kettle is sealed. At 240 °C, with a pressure of 0.35 MPa and a steam top temperature of 135 °C, the mixture is stirred and reacted at 45 r / min until 98% of the theoretical value of the esterification water stock is reached. The pressure is released and the mixture is transferred to a polycondensation kettle. Then, 1.4 parts of dihydroxy DOPO and 1.97 parts of tetrapod zinc oxide whiskers are added. At 260 °C, the vacuum is pumped to a vacuum degree of less than 50 Pa, and the mixture is stirred and reacted at 75 r / min until the viscosity increases and the Weissenberg effect appears. The reaction is stopped, nitrogen is filled to relieve the vacuum, the reaction kettle is pressurized and extruded, pelletized, added to a twin-screw extruder, extruded at 275 °C and 90 rpm, and then biaxially stretched into a film to obtain a modified polyester film. The remaining steps are the same as those in Example 2.

[0078] Comparative Example 5:

[0079] The preparation method of the high-temperature resistant release film for thermal transfer of Comparative Example 5 is different from that of Example 2 in that steps (3) and (4) are not carried out, and step (5) is modified as follows: by mass fraction, 3.5 parts of terephthalic acid, 0.54 parts of ethylene glycol, 1.20 parts of 1,6-hexanediol, 1.41 parts of pyridinium cationic phenazinone diester, and 0.04 parts of tetrabutyl titanate are mixed evenly. Under a nitrogen atmosphere, the reaction kettle is sealed. At 240 °C, with a pressure of 0.35 MPa and a steam top temperature of 135 °C, stirring reaction is carried out at 45 r / min until 98% of the theoretical value of the esterification water stock is reached. The pressure is released and transferred to the polycondensation kettle. Then 1.44 parts of dihydroxy DOPO are added. At 260 °C, the vacuum is pumped to a vacuum degree less than 50 Pa, and stirring reaction is carried out at 75 r / min until the viscosity rises and the Weissenberg effect appears. The reaction is stopped, nitrogen is filled to relieve the vacuum, the pressure is applied to extrude the reaction kettle, pelletized, added to a twin-screw extruder, and extruded at 275 °C and 90 rpm and then biaxially stretched into a film to obtain a modified polyester film. The remaining steps are the same as those in Example 2.

[0080] Comparative Example 6:

[0081] The preparation method of the high-temperature resistant release film for thermal transfer of Comparative Example 6 is different from that of Example 2 in step (5). Step (5) is modified as follows: by mass fraction, 3.5 parts of terephthalic acid, 0.8 parts of ethylene glycol, 1.17 parts of 1,6-hexanediol, 1.37 parts of pyridinium cationic phenazinone diester, and 0.04 parts of tetrabutyl titanate are mixed evenly. Under a nitrogen atmosphere, the reaction kettle is sealed. At 240 °C, with a pressure of 0.35 MPa and a steam top temperature of 135 °C, stirring reaction is carried out at 45 r / min until 98% of the theoretical value of the esterification water stock is reached. The pressure is released and transferred to the polycondensation kettle. Then 1.97 parts of modified zinc oxide are added. At 260 °C, the vacuum is pumped to a vacuum degree less than 50 Pa, and stirring reaction is carried out at 75 r / min until the viscosity rises and the Weissenberg effect appears. The reaction is stopped, nitrogen is filled to relieve the vacuum, the pressure is applied to extrude the reaction kettle, pelletized, added to a twin-screw extruder, and extruded at 275 °C and 90 rpm and then biaxially stretched into a film to obtain a modified polyester film. The remaining steps are the same as those in Example 2.

[0082] Test Example 1:

[0083] Mechanical property test: Refer to GB / T 1040.3-2006 to test the tensile strength. Type 5 specimens are used, and the tensile rate is 5 mm / min. 5 samples are tested in each group, and the average value is taken for recording.

[0084] Anti-aging performance test: Samples were prepared with reference to the mechanical property test. Then, in accordance with the standard of GB / T 16422.3-2022, the samples were subjected to artificial accelerated aging for 10 days using an FR-1205-QUV ultraviolet aging test machine. The tensile strength was measured again, and the tensile strength retention rate was calculated by comparing it with the tensile strength obtained in the mechanical property test. Each group of samples was tested 5 times repeatedly, and the average value was recorded.

[0085] Antistatic performance test: The surface resistivity of the non-coated surface of the prepared high-temperature resistant release film for thermal transfer was tested with reference to the standard of GB / T 31838.3-2019. A JEST-121 type volume surface resistance tester was used for the test. The size of the sample was 100mm×100mm×1mm. The sample was pretreated for 96h at 23°C and a relative humidity of 50%. With the electrode device for measuring flat specimens, a voltage of 100V was applied, and the surface resistance was measured after electrification for 1 minute. The surface resistivity was calculated according to the formula in the standard. Each group of samples was tested in parallel 5 times, and the average value was recorded.

[0086] The results are shown in Table 1.

[0087] Table 1

[0088] Tensile strength / MPa Strength retention rate Surface resistivity / Ω Example 1 88.47 96.45% <![CDATA[8.37×10 5 > Example 2 89.58 97.23% <![CDATA[4.56×10 5 > Example 3 88.79 96.88% <![CDATA[7.28×10 5 > Comparative example 1 65.37 94.36% <![CDATA[6.48×10 7 <!-- 8 -->]]> Comparative example 2 73.45 93.22% <![CDATA[5.64×10 7 > Comparative example 3 77.48 87.38% <![CDATA[9.32×10 5 > Comparative example 4 68.96 79.24% <![CDATA[7.84×10 9 > Comparative example 5 53.44 58.44% <![CDATA[4.56×10 13 > Comparative example 6 80.32 96.76% <![CDATA[7.49×10 5 >

[0089] From the comparison of the experimental data of Examples 1-3 and Comparative Examples 1-6 in Table 1, it can be found that the high-temperature resistant release film for thermal transfer prepared by the present invention has good tensile strength, anti-aging performance and antistatic performance.

[0090] By comparing the data in the table, the data of Comparative Example 1 and Comparative Example 2 show that ethyl chloroacetate successfully undergoes a quaternization reaction with the pyridine group on dipyridylphenazine ketone to form a pyridinium cation, and a binary ester group is introduced. The ester group allows it to participate in the polycondensation of the polyester main chain through an ester exchange reaction, thereby entering the polyester main chain and providing an improvement in tensile strength. At the same time, the pyridinium cation also improves the electrical conductivity and further enhances the antistatic performance. The higher tensile strength of Comparative Example 2 than that of Comparative Example 1 is presumably due to the fact that pyridinium cation-based phenazine ketone diester was not added, and the molar amounts of acid and alcohol added were re-compounded to make their ratio of alcohol to acid corresponding. In Comparative Example 1, this step was not carried out because dipyridylphenazine ketone was added; the data of Comparative Example 3 show that further modification of mercapto-modified zinc oxide with a coumarin derivative effectively improves the dispersion performance of the modified zinc oxide, and the hydroxyl group introduced by the coumarin derivative allows it to be fixed in the polyester network in the form of a covalent bond, further improving the tensile strength. At the same time, the introduced coumarin group has ultraviolet absorption performance, effectively enhancing the anti-aging performance; the data of Comparative Example 4 show that the modification of tetrapod-shaped zinc oxide whiskers effectively improves their dispersion performance in the matrix, effectively improving the improvement of tetrapod-shaped zinc oxide whiskers in terms of tensile strength and antistatic performance. At the same time, the thioether group and coumarin group introduced by the modification both have good anti-aging performance and play a synergistic role with zinc oxide, fully improving the anti-aging performance; the data of Comparative Example 5 show that the addition of modified zinc oxide effectively enhances the tensile strength, anti-aging performance and antistatic performance; the data of Comparative Example 6 show that the rigid structure of dihydroxy DOPO effectively enhances the tensile strength.

[0091] Test Example 2:

[0092] Flame retardancy test: The limiting oxygen index and UL 94 combustion rating of the prepared high-temperature resistant release film for thermal transfer were tested to evaluate its flame retardancy effect. The specific test method is as follows:

[0093] Limiting oxygen index test: According to GB / T 2406.1-2008, the limiting oxygen index of the high-temperature resistant release film for thermal transfer prepared in the examples and comparative examples was tested with an oxygen index instrument. The specimen size was 150 mm × 10 mm × 3 mm, and the average value of 5 specimens in each group was taken and recorded;

[0094] Vertical combustion test: According to ASTM D3801-2010, a vertical-horizontal combustion tester was used for testing, and the average value of 5 specimens in each group was taken and recorded.

[0095] The results are shown in Table 2.

[0096] Table 2

[0097] Limiting oxygen index UL 94 rating Example 1 31.48% V-0 Example 2 32.44% V-0 Example 3 31.89% V-0 Comparative example 1 31.24% V-0 Comparative example 2 31.35% V-0 Comparative example 3 31.08% V-0 Comparative example 4 30.89% V-0 Comparative example 5 28.56% V-1 Comparative example 6 23.88% V-2

[0098] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 6 in Table 2, it can be found that the high-temperature resistant release film for thermal transfer prepared by the present invention has good flame retardant properties.

[0099] Through the comparison of the data in the table, the data of Comparative Example 5 shows that the addition of modified zinc oxide improves the flame retardant properties. Zinc oxide, as a metal oxide, also has a certain flame retardant effect; the data of Comparative Example 6 shows that the addition of dihydroxy DOPO introduces the flame retardant element phosphorus, effectively improving the flame retardant effect.

[0100] Test Example 3:

[0101] High-temperature resistance test: Use a TG 209 thermogravimetric analyzer produced by Netzsch Instruments Germany GmbH to conduct thermogravimetric tests on the specimens; take 1 - 5 mg of the specimens in a crucible, purge with nitrogen, the test temperature is 25 - 900 °C, the heating rate is 20 °C / min, record the 10% thermal decomposition temperature, conduct 5 parallel tests for each group, and take the average value for recording.

[0102] The results are shown in Table 3.

[0103] Table 3

[0104] 10% Thermal decomposition temperature / °C 10% Thermal decomposition temperature / °C Example 1 390.4 Comparative example 1 364.3 Example 2 392.1 Comparative example 2 366.7 Example 3 391.5 Comparative example 3 390.1 Comparative example 4 385.6 Comparative example 5 376.2 ​ 384.2

[0105] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 6 in Table 3, it can be found that the high-temperature resistant release film for thermal transfer prepared by the present invention has good high-temperature resistance.

[0106] Through the comparison of the data in the table, the data of Comparative Example 1 and Comparative Example 2 show that the introduction of the phenazine ketone group effectively improves the heat resistance; the data of Comparative Example 4 shows that the modification of tetrapod zinc oxide whiskers improves its dispersion in the matrix, improving the contribution of zinc oxide to the heat resistance performance; the data of Comparative Example 5 shows that the addition of modified zinc oxide can improve the high-temperature resistance; the data of Comparative Example 6 shows that the rigid group of dihydroxy DOPO also makes a certain contribution to the high-temperature resistance performance.

[0107] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-temperature resistant release film for thermal transfer, characterized in that, The high-temperature resistant release film for thermal transfer is prepared by coating a release agent on a modified polyester film; The modified polyester film is prepared by reacting terephthalic acid, ethylene glycol, 1,6-hexanediol, pyridinium cationic phenazinone diester, dihydroxy DOPO, and modified zinc oxide by polycondensation, pelletizing, extruding, and stretching into a film; The pyridinium cationic phenazinone diester is prepared by reacting bispyridyl phenazinone with ethyl chloroacetate; The bispyridyl phenazinone is prepared by reacting 4-isocyanatopyridine with 4-(4-pyridylmethyl)-1(2H)-phthalazinone; The modified zinc oxide is prepared by reacting mercapto-modified zinc oxide with a coumarin derivative; The mercapto-modified zinc oxide is prepared by reacting tetrapod-shaped zinc oxide whiskers with 3-mercaptopropyltrimethoxysilane; 2. The high-temperature resistant release film for thermal transfer according to claim 1, wherein, The coumarin derivative is 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin; 3. A high-temperature resistant release film for thermal transfer according to claim 1, characterized in that, The surface resistivity of the tetrapod-like zinc oxide whiskers is less than 10 4 Ω.

4. A preparation method of a high-temperature resistant release film for thermal transfer, characterized in that It includes the following preparation steps: (1) Under a nitrogen atmosphere, mix 4-isocyanatopyridine and N,N-dimethylformamide, stir, add 4-(4-pyridylmethyl)-1(2H)-phthalazinone, continue stirring, raise the temperature, add dibutyltin dilaurate, stir and react, cool, rotary evaporate, and dry to obtain bispyridyl phenazinone; (2) Mix bispyridyl phenazinone and N,N-dimethylformamide, add ethyl chloroacetate, react, precipitate in acetone, filter by suction, wash, and dry to obtain pyridinium cationic phenazinone diester; (3) Mix absolute ethanol, pure water, and tetrapod-shaped zinc oxide whiskers, ultrasonicate, add 3-mercaptopropyltrimethoxysilane, adjust the pH, heat under reflux and react, filter by suction, wash, and dry to obtain mercapto-modified zinc oxide; (4) Mix 7-[(6,7-dihydroxy-3,7-dimethyl-2-octen-1-yl)oxy]coumarin, mercapto-modified zinc oxide, and tetrahydrofuran, stir, add azobisisobutyronitrile, heat and stir under reflux, filter by suction, wash, and dry to obtain modified zinc oxide; (5) Mix terephthalic acid, ethylene glycol, 1,6-hexanediol, pyridinium cationic phenazinone diester, and tetrabutyl titanate. Under a nitrogen atmosphere, seal the reaction kettle, heat and pressurize the reaction until 98% of the theoretical value of the esterification water stock is reached, relieve the pressure and transfer it to the polycondensation kettle. Then add dihydroxy DOPO and modified zinc oxide, heat, evacuate to vacuum, stir and react until the viscosity rises and the Weissenberg effect appears, stop the reaction, fill with nitrogen to relieve the vacuum, pressurize and extrude from the reaction kettle, pelletize, add to a twin-screw extruder and extrude and stretch into a film to obtain a modified polyester film; (6) Coat the release agent on the modified polyester film and place it in a vacuum oven at 80-90 °C for 4-5 h to obtain the high-temperature resistant release film for thermal transfer.

5. The preparation method of a high-temperature resistant release film for thermal transfer according to claim 4, characterized in that, The bipyridylphenazinone described in step (1) is prepared by mixing 2 - 3 parts by mass of 4 - isocyanatopyridine and 12 - 15 parts by mass of N,N - dimethylformamide evenly under a nitrogen atmosphere, stirring at 300 - 400 r / min for 30 - 40 min at room temperature, adding 3.95 - 5.93 parts by mass of 4-(4 - pyridylmethyl)-1(2H)-phthalazinone, continuing to stir for 20 - 30 min, then heating to 105 - 110 °C, adding 0.009 - 0.013 parts by mass of dibutyltin dilaurate, stirring and reacting at 400 - 500 r / min for 4 - 5 h, cooling naturally to room temperature, removing the solvent by rotary evaporation, and drying in vacuo at 50 - 60 °C for 10 - 12 h.

6. The preparation method of a high-temperature resistant release film for thermal transfer according to claim 4, characterized in that, The pyridinium cationic phenazinone diester described in step (2) is prepared by mixing 2 - 3 parts by mass of bipyridylphenazinone and 12 - 15 parts by mass of N,N - dimethylformamide evenly, adding 1.51 - 2.37 parts by mass of ethyl chloroacetate, reacting at 60 - 65 °C and 300 - 400 r / min for 22 - 24 h, precipitating in 20 - 25 parts by mass of acetone for 50 - 60 min, filtering by suction, washing 3 - 4 times with absolute ethanol, and drying in vacuo at 50 - 60 °C for 10 - 12 h.

7. The preparation method of a high-temperature resistant release film for thermal transfer according to claim 4, characterized in that, The mercapto - modified zinc oxide described in step (3) is prepared by mixing 10 - 12 parts by mass of absolute ethanol, 1 - 1.2 parts by mass of pure water, and 0.4 - 0.5 parts by mass of tetrapod - shaped zinc oxide whiskers evenly, ultrasonicating at 40 °C for 30 - 35 min, adding 0.5 - 0.7 parts by mass of 3 - mercaptopropyltrimethoxysilane, adjusting the pH to 8 - 9 with 6 mol / L ammonia water, refluxing and reacting at 80 °C and 300 - 400 r / min for 8 - 10 h, filtering by suction, washing 3 - 4 times with absolute ethanol, and drying in vacuo at 50 - 60 °C for 8 - 10 h.

8. The preparation method of a high-temperature resistant release film for thermal transfer according to claim 4, characterized in that, The modified zinc oxide described in step (4) is prepared by mixing 1 - 1.5 parts by mass of 7 - [(6,7 - dihydroxy - 3,7 - dimethyl - 2 - octen - 1 - yl)oxy]coumarin, 1 - 1.2 parts by mass of mercapto - modified zinc oxide, and 10 - 12 parts by mass of tetrahydrofuran evenly, stirring at 400 - 500 r / min for 30 - 40 min, adding 0.01 - 0.012 parts by mass of azobisisobutyronitrile, stirring and refluxing at 75 - 80 °C and 400 - 500 r / min for 8 - 10 h, filtering by suction, washing 3 - 4 times alternately with absolute ethanol and pure water, and drying in vacuo at 40 - 50 °C for 10 - 12 h.

9. The preparation method of a high-temperature resistant release film for thermal transfer according to claim 4, characterized in that, The modified polyester film described in step (5) is prepared by mixing 3-4 parts of terephthalic acid, 0.48-0.57 parts of ethylene glycol, 0.97-1.38 parts of 1,6-hexanediol, 1.18-1.57 parts of pyridinium cationic phenazinone diester, and 0.03-0.05 parts of tetrabutyl titanate by mass. Under a nitrogen atmosphere, the reaction kettle is sealed. At 230-250 °C, a pressure of 0.3-0.4 MPa, and a steam tower top temperature of 120-150 °C, the mixture is stirred at 40-50 r / min until 98% of the theoretical value of the esterification water stock is reached. Then, the pressure is relieved and the mixture is transferred to a polycondensation kettle. Next, 1.14-1.69 parts of dihydroxy DOPO and 1.69-2.26 parts of modified zinc oxide are added. At 250-270 °C, the vacuum is pumped to a vacuum degree less than 50 Pa, and the mixture is stirred at 70-80 r / min until the viscosity rises and the Weissenberg effect appears. The reaction is stopped, nitrogen is filled to relieve the vacuum, and the mixture is pressed out of the reaction kettle under pressure, pelletized, added to a twin-screw extruder, and extruded at 270-280 °C and 80-100 rpm, and then biaxially stretched into a film.