High-temperature-reaction-resistant halogen-free flame-retardant TPU (thermoplastic polyurethane) adhesive film and preparation method thereof

Abstract

The invention relates to the technical field of adhesive films, in particular to a high-temperature-reaction-resistant halogen-free flame-retardant TPU (thermoplastic polyurethane) adhesive film and a preparation method thereof. The high-temperature-resistant reaction type halogen-free flame-retardant TPU adhesive film is prepared from the following raw materials in parts by weight: 60 to 90 parts of polycaprolactone polyol, 10 to 40 parts of reaction type halogen-free flame-retardant dihydric alcohol, 3 to 10 parts of micromolecule chain extender, 0.01 to 0.1 part of catalyst and 22.5 to 68.2 parts of diisocyanate. Wherein the number-average molecular weight of the polycaprolactone polyol is 1000 to 2000 g / mol, and the number-average molecular weight of the polycaprolactone polyol is 1000 to 2000 g / mol The ratio of the mole number of isocyanate groups in the diisocyanate to the total mole number of hydroxyl groups in the polycaprolactone polyol and the reaction type halogen-free flame-retardant dihydric alcohol is 0.98-1.05; the TPU adhesive film prepared by the preparation method disclosed by the invention not only has the characteristics of high transparency and excellent hydrolysis resistance, but also has excellent mechanical property and flame retardant property, so that the quality of the prepared TPU adhesive film is effectively ensured.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of adhesive films, in particular to a high-temperature-resistant reactive halogen-free flame-retardant TPU adhesive film and a preparation method thereof. BACKGROUND

[0002] The thermoplastic polyurethane (TPU) adhesive film is widely used due to its excellent elasticity, wear resistance and bonding performance. However, the traditional TPU is extremely flammable, which limits its use in fields with strict safety requirements. To solve this problem, the method of adding a flame retardant is usually adopted, and the halogen-free flame retardant becomes the mainstream due to environmental protection requirements. However, the prepared additive type halogen-free flame-retardant TPU adhesive film has the following obvious defects: 1. Compatibility and migration problem: the small molecule flame retardant has poor compatibility with the TPU matrix and is easy to migrate and precipitate (blooming), which leads to the attenuation of the flame-retardant performance with time and affects the appearance and bonding performance of the adhesive film.

[0003] 2. Loss of mechanical properties: a high amount of flame retardant will seriously damage the microphase separation structure of the TPU, leading to a significant decrease in the mechanical properties such as tensile strength and elongation.

[0004] 3. Influence on transparency: the addition of the flame retardant will lead to an increase in the haze of the adhesive film and a decrease in the transparency, which is difficult to meet the requirements of applications with optical performance.

[0005] Based on the above, the application provides a high-temperature-resistant reactive halogen-free flame-retardant TPU adhesive film and a preparation method thereof to solve the above technical problems. SUMMARY

[0006] The application provides a high-temperature-resistant reactive halogen-free flame-retardant TPU adhesive film, and the prepared TPU adhesive film has the characteristics of high transparency and excellent hydrolysis resistance, and also has excellent mechanical properties and flame-retardant properties, which effectively ensures the quality of the prepared TPU adhesive film.

[0007] To achieve the above purpose, the application provides the following technical scheme: A high-temperature-resistant reactive halogen-free flame-retardant TPU adhesive film is prepared from the following raw materials in parts by weight: 60-90 parts of polycaprolactone polyol, 10-40 parts of reactive halogen-free flame-retardant diol, 3-10 parts of small molecule chain extender, 0.01-0.1 parts of catalyst and 22.5-68.2 parts of diisocyanate.

[0008] Further, the number average molecular weight of the polycaprolactone polyol is 1000-2000 g / mol; the regular molecular structure of the polycaprolactone polyol is beneficial to crystallization, and provides good initial adhesion and final bonding strength for the adhesive film; meanwhile, the ester bond stability of the polycaprolactone polyol is higher than that of ordinary polyester polyol, which endows the adhesive film with excellent hydrolysis resistance, and the compatibility of the polycaprolactone polyol with other materials also helps to realize high transparency.

[0009] Further, the ratio of the number of moles of isocyanate groups in the diisocyanate to the total number of moles of hydroxyl groups in the polycaprolactone polyol and the reactive halogen-free flame-retardant diol is 0.98-1.05.

[0010] Further, the preparation method of the reactive halogen-free flame-retardant diol comprises the following steps: Step 1, add DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) into dimethylbenzene with 15-20 times of the mass of DOPO, uniformly mix and stir, then add a quinone compound with the same molar amount as DOPO, uniformly mix and stir under magnetic stirring, and then react at 110-125℃ for 4-6h; after the reaction is completed, the organic solvent is evaporated and recovered to obtain an intermediate product; wherein the quinone compound is p-benzoquinone or 1,4-naphthoquinone; Step 2, under nitrogen protection, add ethylene glycol with 2-2.5 times the molar amount of the quinone compound and p-toluenesulfonic acid catalyst with 2-4% of the mass of the quinone compound into the intermediate product, uniformly mix and stir, then react at 160-180℃ for 6-8h; after the reaction is completed, cool the reaction system to room temperature, remove the unreacted monomers and by-products by reduced pressure distillation, and then wash and dry to obtain the reactive halogen-free flame-retardant diol; wherein the reactive halogen-free flame-retardant diol can directly participate in the polyurethane synthesis reaction, and the phosphorus and nitrogen elements are firmly embedded in the TPU molecular chain in the form of chemical bonds to achieve intrinsic flame retardation.

[0011] Further, the diisocyanate is any one of 4,4'-diphenylmethane diisocyanate and 4,4'-dicyclohexylmethane diisocyanate. Among them, the diisocyanate can provide better yellowing resistance and transparency.

[0012] Further, the small molecule chain extender is any one of 1,4-butanediol, propylene glycol, neopentyl glycol, and 1,6-hexanediol.

[0013] Further, the catalyst is any one of bismuth neodecanoate, bismuth iso-octoate, bismuth oleate, and bismuth laurate.

[0014] A preparation method of a high-temperature-resistant reactive halogen-free flame-retardant TPU adhesive film, comprising the following steps: Step 1, weigh each raw material according to the formula amount, and dehydrate the polycaprolactone polyol and the reactive halogen-free flame-retardant diol under the conditions of a temperature of 100-120℃ and a vacuum degree of less than -0.095MPa until the water content of both is less than 0.03%; Step two, the polycaprolactone polyols and reactive halogen-free flame retardant diols mixture after dehydration are naturally cooled to 75-85℃, then the diisocyanate is added under the protection of nitrogen, and after uniform stirring at a speed of 200-300r / min, the reaction is kept at a temperature of 75-85℃ for 1-2h; after the reaction is completed, the obtained prepolymer is stored for use; Step three, the catalyst and the small molecule chain extender with a temperature of 75-85℃ are added to the prepolymer, and after uniform mixing and stirring, the obtained mixture is cast on the surface of a mirror surface steel plate or a release paper, and then after curing, cooling and peeling, the high-temperature resistant reactive halogen-free flame retardant TPU film product is obtained.

[0015] Further, the speed of the mixing and stirring in step three is set to 150-250r / min, and the mixing and stirring time is set to 30-60s.

[0016] Further, the temperature of the oven during the curing in step three is set to 100-120℃, and the curing time is set to 2-4h.

[0017] Compared with the prior art, the present application has the following advantages: 1. The polycaprolactone polyol is used as the soft segment in the present application, which has a regular molecular structure and helps to form a transparent film. At the same time, the ester bond in the molecular chain is more stable than that in ordinary polyester polyols (such as PBA), which can significantly improve the hydrolysis resistance of the film.

[0018] 2. In the present application, DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and quinone compounds, ethylene glycol, etc. are used as raw materials to prepare a reactive halogen-free flame retardant diol containing phosphorus, nitrogen and other synergistic flame retardant elements through two-step chemical reactions. Then, the flame retardant structure unit is embedded into the TPU molecular main chain through chemical bonding using the prepared reactive halogen-free flame retardant diol as raw material. Compared with the simple physical blending of additive flame retardants, this method avoids the migration and precipitation of small molecules, thereby realizing permanent and environmentally friendly halogen-free flame retardation, and has less impact on the transparency and mechanical properties of the material.

[0019] 3. The present application utilizes the good compatibility between polycaprolactone polyol and reactive flame retardant. The matching of the refractive indexes of the two ensures that the prepared TPU film has the advantage of high transparency (transmittance ≥ 90%). Furthermore, the inherent hydrolysis resistance of polycaprolactone polyol combined with the stable chemical bonding characteristics of the reactive flame retardant ensures that the final product can still maintain stable performance in a humid and hot harsh environment for a long time.

[0020] 4. The prepolymer synthesis process (first synthesizing an-NCO prepolymer, then adding a chain extender) used in the present application is beneficial to the control of molecular weight and its distribution, thereby ensuring the uniformity of film quality and excellent performance. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0022] Embodiment 1 A high-temperature-resistant reaction type halogen-free flame-retardant TPU adhesive film is composed of the following raw materials in parts by weight: 60 parts of polycaprolactone polyol, 10 parts of reaction type halogen-free flame-retardant diol, 3 parts of 1,4-butanediol, 0.01 parts of bismuth neodecanoate, and 22.5 parts of 4,4'-diphenyl methane diisocyanate. The number average molecular weight of the polycaprolactone polyol is 1000 g / mol. The ratio of the number of moles of isocyanate groups in the diisocyanate to the total number of moles of hydroxyl groups in the polycaprolactone polyol and the reaction type halogen-free flame-retardant diol is 0.98.

[0023] The preparation method of the reaction type halogen-free flame-retardant diol comprises the following steps: In the first step, DOPO is added to dimethylbenzene with a mass of 15 times that of DOPO, and after uniform mixing and stirring, an equimolar amount of p-benzoquinone is added. After uniform magnetic stirring, the reaction is carried out at 110℃ for 6h. After the reaction is completed, the organic solvent is distilled off and recovered to obtain an intermediate product. In the second step, under nitrogen protection, the intermediate product is added with ethylene glycol with a molar amount of 2 times that of p-benzoquinone and p-toluenesulfonic acid catalyst with a mass of 2% of p-benzoquinone. After uniform mixing and stirring, the reaction is carried out at 160℃ for 8h. After the reaction is completed, the reaction system is cooled to room temperature, and unreacted monomers and by-products are removed by reduced pressure distillation. After washing and drying, the reaction type halogen-free flame-retardant diol is obtained.

[0024] A preparation method of a high-temperature-resistant reaction type halogen-free flame-retardant TPU adhesive film comprises the following steps: In step one, the raw materials are weighed according to the formula amount, and the polycaprolactone polyol and the reaction type halogen-free flame-retardant diol are dehydrated under the condition of a temperature of 100℃ and a vacuum degree lower than-0.095MPa until the water content of both is lower than 0.03%; In step two, the mixture of the dehydrated polycaprolactone polyol and the reaction type halogen-free flame-retardant diol is naturally cooled to 75℃, and then the diisocyanate is added under the protection of nitrogen. After uniform stirring at a speed of 200r / min, the reaction is carried out at a temperature of 75℃ for 2h. After the reaction is completed, the obtained prepolymer is stored and used. Step 3: Add the catalyst and the small molecule chain extender at 75℃ to the prepolymer, mix and stir evenly, then cast the resulting mixture onto the surface of the mirror steel plate or release paper, and then cure, cool and peel off in sequence to obtain the high temperature resistant reactive halogen-free flame retardant TPU film. The mixing speed was set to 150 r / min and the mixing time was set to 60 s; the oven temperature during maturation was set to 100 ℃ and the maturation time was set to 4 h.

[0025] Example 2: A high-temperature resistant reactive halogen-free flame-retardant TPU film is composed of the following raw materials in parts by weight: 80 parts polycaprolactone polyol, 20 parts reactive halogen-free flame-retardant diol, 6 parts 1,4-butanediol, 0.05 parts bismuth isooctanoate and 38 parts 4,4'-dicyclohexylmethane diisocyanate. Among them, the number average molecular weight of polycaprolactone polyol is 2000 g / mol; The ratio of the molar number of isocyanate groups in the diisocyanate to the total molar number of hydroxyl groups in the polycaprolactone polyol and the reactive halogen-free flame-retardant diol is 1.02.

[0026] The preparation method of the reactive halogen-free flame-retardant diol includes the following steps: Step 1: Add DOPO to xylene in 15 times its mass, mix and stir well, then add 1,4-naphthoquinone in an equimolar amount of DOPO, stir magnetically until well mixed, and react at 120°C for 5 hours; after the reaction is complete, evaporate and recover the organic solvent to obtain the intermediate product. The second step involves adding ethylene glycol in a molar amount twice that of 1,4-naphthoquinone and p-toluenesulfonic acid catalyst in a mass of 3% of 1,4-naphthoquinone to the intermediate product under nitrogen protection. After mixing and stirring evenly, the mixture is reacted at 170°C for 7 hours. After the reaction is complete, the reaction system is cooled to room temperature, and unreacted monomers and byproducts are removed by vacuum distillation. After washing and drying, the reactive halogen-free flame-retardant diol is obtained.

[0027] A method for preparing a high-temperature resistant reactive halogen-free flame-retardant TPU film includes the following steps: Step 1: Weigh each raw material according to the formula, and dehydrate the polycaprolactone polyol and the reactive halogen-free flame retardant diol at a temperature of 110℃ and a vacuum degree of less than -0.095MPa until the moisture content of both is less than 0.03%. Step 2: Allow the mixture of dehydrated polycaprolactone polyol and reactive halogen-free flame-retardant diol to cool naturally to 80°C. Then, add diisocyanate under nitrogen protection and stir at 250 r / min until homogeneous. Keep the mixture at 80°C for 2 hours. After the reaction is complete, store the resulting prepolymer for later use. Step 3: Add the catalyst and the small molecule chain extender at 80℃ to the prepolymer, mix and stir evenly, then cast the resulting mixture onto the surface of the mirror steel plate or release paper, and then cure, cool and peel off in sequence to obtain the high temperature resistant reactive halogen-free flame retardant TPU film. The mixing speed was set to 200 r / min and the mixing time was set to 50 s; the oven temperature during maturation was set to 110 ℃ and the maturation time was set to 3 h.

[0028] Example 3: A high-temperature resistant reactive halogen-free flame-retardant TPU film is composed of the following raw materials in parts by weight: 90 parts polycaprolactone polyol, 40 parts reactive halogen-free flame-retardant diol, 10 parts 1,4-butanediol, 0.1 parts bismuth laurate and 68.2 parts 4,4'-diphenylmethane diisocyanate. Among them, the number average molecular weight of polycaprolactone polyol is 2000 g / mol; The ratio of the molar number of isocyanate groups in the diisocyanate to the total molar number of hydroxyl groups in the polycaprolactone polyol and the reactive halogen-free flame-retardant diol is 1.05.

[0029] The preparation method of the reactive halogen-free flame-retardant diol includes the following steps: Step 1: Add DOPO to xylene in 20 times its mass, mix and stir evenly, then add p-benzoquinone in an equimolar amount of DOPO, stir magnetically evenly, and react at 125°C for 4 hours; after the reaction is complete, evaporate and recover the organic solvent to obtain the intermediate product. The second step involves adding ethylene glycol (2.5 times the molar amount of p-benzoquinone) and p-toluenesulfonic acid catalyst (4% by mass of p-benzoquinone) to the intermediate product under nitrogen protection. After mixing and stirring evenly, the mixture is reacted at 180°C for 6 hours. After the reaction is complete, the reaction system is cooled to room temperature, and unreacted monomers and byproducts are removed by vacuum distillation. After washing and drying, the reactive halogen-free flame-retardant diol is obtained.

[0030] A method for preparing a high-temperature resistant reactive halogen-free flame-retardant TPU film includes the following steps: Step 1: Weigh each raw material according to the formula, and dehydrate the polycaprolactone polyol and the reactive halogen-free flame retardant diol at a temperature of 120℃ and a vacuum degree of less than -0.095MPa until the moisture content of both is less than 0.03%. Step 2: Allow the mixture of dehydrated polycaprolactone polyol and reactive halogen-free flame-retardant diol to cool naturally to 85°C. Then, add diisocyanate under nitrogen protection and stir at 300 r / min until homogeneous. Keep the mixture at 85°C for 1 hour. After the reaction is complete, store the resulting prepolymer for later use. Step 3: Add the catalyst and the small molecule chain extender at 85℃ to the prepolymer, mix and stir evenly, then cast the resulting mixture onto the surface of a mirror steel plate or release paper, and then cure, cool and peel off in sequence to obtain the high temperature resistant reactive halogen-free flame retardant TPU film. The mixing speed was set to 250 r / min and the mixing time was set to 30 s; the oven temperature during maturation was set to 120 ℃ and the maturation time was set to 2 h.

[0031] Comparative Example 1: The preparation process of the TPU film in this comparative example is basically similar to that in Example 2, except that the high-temperature resistant reactive halogen-free flame retardant TPU film prepared in this comparative example is composed of the following parts by weight of raw materials: 80 parts of polybutylene adipate (PBA), 20 parts of reactive halogen-free flame retardant diol, 6 parts of small molecule chain extender, 0.1 parts of catalyst and 38 parts of diisocyanate; The number-average molecular weight of polybutylene adipate (PBA) is 2000 g / mol; the ratio of the molar number of isocyanate groups in the diisocyanate to the total molar number of hydroxyl groups in polybutylene adipate (PBA) and reactive halogen-free flame-retardant diol is 1.02.

[0032] Comparative Example 2: The preparation process of the TPU film in this comparative example is basically similar to that in Example 2, except that the high-temperature resistant reactive halogen-free flame-retardant TPU film prepared in this comparative example is composed of the following parts by weight of raw materials: 80 parts of polycaprolactone polyol, 20 parts of ammonium polyphosphate (APP), 6 parts of small molecule chain extender, 0.05 parts of catalyst and 38 parts of diisocyanate. The number-average molecular weight of the polycaprolactone polyol is 2000 g / mol; the ratio of the molar number of isocyanate groups in the diisocyanate to the total molar number of hydroxyl groups in the polycaprolactone polyol and the reactive halogen-free flame-retardant diol is 1.02.

[0033] Performance testing: The relevant properties of the high-temperature resistant reactive halogen-free flame-retardant TPU film samples provided in Examples 1-3 and Comparative Examples 1-2 were tested as follows: 1. Film transparency and haze: Qualitative evaluation is conducted by visual observation, and quantitative analysis is performed when necessary in accordance with the national standard GB / T2410-2008 "Determination of light transmittance and haze of transparent plastics" to evaluate the optical performance of the film.

[0034] 2. Limiting Oxygen Index: Determined according to the national standard GB / T2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test". This index indicates the minimum oxygen concentration required for a material to sustain combustion in a nitrogen-oxygen mixture; the higher the value, the more difficult the material is to burn.

[0035] 3. UL-94 Flame Retardant Rating: The rating is determined according to the American safety testing laboratory standard ANSI / UL94-2013, "Tests on the Flammability of Plastic Materials for Equipment and Appliance Components." The test uses a 1.6 mm thick sample, and the flame retardant rating is determined based on its burning behavior (such as burning time, whether drippings ignite absorbent cotton, etc.). V-0 is one of the highest ratings.

[0036] 4. Tensile strength and elongation at break: Tested according to national standard GB / T1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets". A universal testing machine is used to stretch a standard dumbbell-shaped specimen until it breaks, to determine the maximum tensile strength (MPa) and elongation at break (%).

[0037] 5. Mechanical Property Retention Rate (Tensile Strength Retention Rate): This indicator is used to evaluate the material's heat aging resistance. First, the samples are treated in a heat aging chamber under specific conditions for 500 hours according to the national standard GB / T7141-2008 "Plastics - Test Method for Heat Aging". Then, the tensile strength of the aged samples is tested again according to GB / T1040.3-2006 standard. The mechanical property retention rate is calculated using the following formula: Tensile strength retention rate (%) = (tensile strength after heat aging / tensile strength before heat aging) × 100%.

[0038] The obtained test data is recorded in the table below:

[0039] *Light transmittance and haze were tested according to GB / T2410-2008, and the sample thickness was 0.10±0.02mm.

[0040] By comparing and analyzing the relevant data in the table, it can be seen that the TPU film prepared by this invention not only has high transparency and excellent hydrolysis resistance, but also excellent mechanical properties and flame retardant properties, effectively ensuring the quality of the prepared TPU film. This indicates that the high-temperature reactive halogen-free flame-retardant TPU film and its preparation method provided by this invention have a broader market prospect and are more suitable for widespread application.

[0041] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-temperature resistant reactive halogen-free flame-retardant TPU film, characterized in that, It is composed of the following raw materials in parts by weight: 60-90 parts polycaprolactone polyol, 10-40 parts reactive halogen-free flame retardant diol, 3-10 parts small molecule chain extender, 0.01-0.1 parts catalyst and 22.5-68.2 parts diisocyanate.

2. The high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 1, characterized in that: The number-average molecular weight of the polycaprolactone polyol is 1000-2000 g / mol.

3. The high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 1, characterized in that: The ratio of the molar number of isocyanate groups in the diisocyanate to the total molar number of hydroxyl groups in the polycaprolactone polyol and the reactive halogen-free flame-retardant diol is 0.98-1.

05.

4. The high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 1, characterized in that, The preparation method of the reactive halogen-free flame-retardant diol includes the following steps: Step 1: Add DOPO to xylene at a mass of 15-20 times its mass, mix and stir evenly, then add a quinone compound in an equal molar amount to DOPO, stir magnetically evenly, and react at 110-125℃ for 4-6 hours; after the reaction is complete, evaporate and recover the organic solvent to obtain the intermediate product; wherein the quinone compound is p-benzoquinone or 1,4-naphthoquinone. The second step involves adding ethylene glycol (2-2.5 times the molar amount of the quinone compound) and p-toluenesulfonic acid catalyst (2-4% by mass of the quinone compound) to the intermediate product under nitrogen protection. After mixing and stirring evenly, the mixture is reacted at 160-180°C for 6-8 hours. After the reaction is complete, the reaction system is cooled to room temperature, and unreacted monomers and byproducts are removed by vacuum distillation. After washing and drying, the reactive halogen-free flame-retardant diol is obtained.

5. The high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 1, characterized in that: The diisocyanate is either 4,4'-diphenylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate.

6. The high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 1, characterized in that: The small molecule chain extender is any one of 1,4-butanediol, propylene glycol, neopentyl glycol, and 1,6-hexanediol.

7. The high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 1, characterized in that: The catalyst is any one of bismuth neodecanoate, bismuth isooctanoate, bismuth oleate, and bismuth laurate.

8. A method for preparing a high-temperature resistant reactive halogen-free flame-retardant TPU film according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Weigh each raw material according to the formula, and dehydrate the polycaprolactone polyol and the reactive halogen-free flame retardant diol at a temperature of 100-120℃ and a vacuum degree of less than -0.095MPa until the moisture content of both is less than 0.03%. Step 2: Allow the mixture of dehydrated polycaprolactone polyol and reactive halogen-free flame-retardant diol to cool naturally to 75-85℃. Then, under nitrogen protection, add diisocyanate and stir at 200-300 r / min until homogeneous. Keep the mixture at 75-85℃ for 1-2 hours. After the reaction is complete, store the resulting prepolymer for later use. Step 3: Add the catalyst and the small molecule chain extender at a temperature of 75-85℃ to the prepolymer, mix and stir evenly, then cast the resulting mixture onto the surface of a mirror steel plate or release paper, and then cure, cool and peel off in sequence to obtain the high temperature resistant reactive halogen-free flame retardant TPU film.

9. The method for preparing a high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 8, characterized in that: In step three, the mixing speed is set to 150-250 r / min, and the mixing time is set to 30-60 s.

10. The method for preparing a high-temperature resistant reactive halogen-free flame-retardant TPU film according to claim 8, characterized in that: In step three, the oven temperature is set to 100-120℃ and the curing time is set to 2-4 hours.

Images