Polyurethane resin for heat transfer printing, preparation method of polyurethane resin and heat transfer printing film

Abstract

The invention discloses polyurethane resin for heat transfer printing, a preparation method of the polyurethane resin and a heat transfer printing film, and belongs to the technical field of polyurethane resin. The invention discloses polyurethane resin for heat transfer printing, a preparation method of the polyurethane resin and a heat transfer printing film. The polyurethane resin is prepared from a polyurethane prepolymer, a high-temperature-resistant modified monomer, a cross-linking reinforced monomer, nanoscale microporous glass powder, a self-repairing performance reinforcing agent and a heat curing agent. The resin is synthesized through a high-temperature reaction, the polyurethane prepolymer is obtained through a reaction of 4, 4-diphenylmethane diisocyanate and polyether glycol, the compatibility between the nanoscale microporous glass powder and the polyurethane resin is enhanced through surface modification, and the self-repairing performance enhancer can repair microcracks through heating. The heat transfer film is prepared by adopting an on-line coating technology and comprises a base film layer and a release layer. The resin has excellent high temperature resistance, mechanical property and self-repairing capability, and can effectively prolong the service life and improve the transfer printing effect of the heat transfer printing film.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane resins, and more particularly to a polyurethane resin for thermal transfer, a preparation method thereof, and a thermal transfer film. Background Art

[0002] Thermal transfer technology, a common pattern transfer process, is widely used in industries such as textiles, packaging, electronics, and automotive. This technology transfers the designed pattern from a transfer film to the target substrate surface, offering advantages such as high efficiency, precision, and low cost. However, traditional thermal transfer films often face technical challenges during the high-temperature transfer process, particularly regarding the material's thermal stability and flexibility, as well as the clarity and durability of the pattern during the transfer process.

[0003] Current thermal transfer films are mostly based on polyurethane resin, which is widely used in the production of transfer films due to its excellent adhesion and adaptability. However, the performance of polyurethane resin in the thermal transfer process still needs to be improved, especially in terms of the material's high-temperature resistance, mechanical strength, and transfer stability. Furthermore, the uneven dispersion of nanoporous glass powder in polyurethane resin also limits its application in high-performance thermal transfer films.

[0004] To overcome the shortcomings of existing technologies, researchers have recently attempted to improve the overall performance of polyurethane resins through surface modification and the introduction of self-healing capabilities. Modification of nanoporous glass powders can effectively enhance their compatibility with polyurethane resins, improve dispersibility, and enhance the mechanical properties and thermal stability of membrane materials. Furthermore, the combined use of bio-based polyesters and crosslinkers offers new avenues for enhancing the self-healing properties of polyurethane resins.

[0005] In the future, with the continuous advancement of materials science and nanotechnology, the performance of polyurethane resins is expected to be further enhanced. In particular, research into polyurethane resins and their composites will become a key trend in the development of thermal transfer film technology, particularly in terms of improving dispersibility, enhancing high-temperature resistance, and enabling multifunctional thermal transfer films (such as self-healing and antibacterial properties). By developing new modified materials and optimizing process flows, it is expected that existing technical bottlenecks can be overcome, providing the thermal transfer industry with more efficient, environmentally friendly, and functional material solutions. Summary of the Invention

[0006] The purpose of the present invention is to provide a polyurethane resin for thermal transfer, a preparation method thereof, and a thermal transfer film, which have excellent high temperature resistance, mechanical properties and self-repairing ability, and can effectively improve the service life and transfer effect of the thermal transfer film.

[0007] (1) Polyurethane prepolymer: obtained by the reaction of isocyanate monomer and polyol under the promotion of cobalt succinate catalyst, wherein the isocyanate is 4,4-diphenylmethane diisocyanate and the polyol is polyether diol with a molecular weight of 2000-4000; (2) High temperature resistant modified monomer: fluorinated monomer, wherein the fluorinated monomer is fluorinated vinyl acrylate; (3) a cross-linking enhancing monomer: a cross-linking agent selected from β-ketone compounds, wherein the cross-linking agent is 1,2-cyclohexene-4,5-dione; (4) Nano-scale microporous glass powder: The particle size of the microporous glass powder is 40-100 nm, and the specific surface area of ​​the microporous glass powder is 200-360 m 2 / g, the compatibility of the microporous glass powder with the polyurethane resin is enhanced by surface modification; (5) Self-repairing performance enhancer: Combining bio-based polyester and polyurethane prepolymer, the self-repairing performance enhancer is designed with a reversible chemical bond network, so that the microcracks generated by stress in the resin during the thermal transfer process can be repaired by heating. The self-repairing temperature is 60-90°C and the repair time is 5-9 minutes; (6) Curing agent: Add a thermal curing agent, wherein the thermal curing agent is dimethyl tetrazolidine.

[0008] Preferably, the mass ratio of the isocyanate, the polyol, and the catalyst cobalt succinate is 1:8-16:0.01-0.03.

[0009] Preferably, the mass fraction of the high temperature resistant modified monomer is 2-4% of the total mass of the polyurethane prepolymer.

[0010] Preferably, the mass fraction of the cross-linking enhancing monomer is 1-2% of the total mass of the polyurethane prepolymer.

[0011] Preferably, the mass fraction of the nano-scale microporous glass powder is 4-6% of the total mass of the polyurethane prepolymer.

[0012] Preferably, the surface modification method of the nanoporous glass powder is: washing the nanoporous glass powder with deionized water and drying it, then placing anhydrous ethanol solvent and the nanoporous glass powder in a reaction container, ultrasonically dispersing them evenly, adding γ-aminopropyltriethoxysilane, ultrasonically dispersing them evenly, stirring and reacting at 50-70°C for 2-4 hours, then adding surfactant Tween 80, ultrasonically dispersing them evenly, and then adding 1,6-hexamethylene diisocyanate, the mass ratio of the five is 30-50:10:0.1-0.3:0.01-0.03:0.06-0.1, ultrasonically dispersing them evenly, stirring and reacting at 70-90°C for 2-4 hours, centrifuging, washing with anhydrous ethanol and drying to obtain modified nanoporous glass powder.

[0013] Preferably, the mass fraction of the self-repairing performance enhancer is 3-5% of the total mass of the polyurethane prepolymer.

[0014] Preferably, the preparation method of the self-repairing performance enhancer is as follows: 1,6-hexanediol, 1,6-hexamethylene diisocyanate, and catalyst cobalt succinate are added to a reaction vessel in a mass ratio of 1:4.2-7:0.01-0.03, placed in a high-speed disperser and mixed evenly, the temperature is controlled at 80-120°C, the stirring reaction time is 4-6h, and after the reaction is completed, a polyurethane prepolymer containing a certain proportion of isocyanate groups is obtained, soybean oil and catalyst aluminum trifluorochloride are added in a mass ratio of 1:0.01-0.03 The mixture was added into a reaction vessel in a ratio of 3-5:1:0.01-0.03, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 160-180°C, the stirring reaction time was 120-180 minutes, and after the reaction was completed, a bio-based polyester extracted from soybean oil was obtained, which was added into a reaction vessel with a polyurethane prepolymer and a catalyst lead tetrachloride in a mass ratio of 3-5:1:0.01-0.03, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 70-90°C, the stirring reaction time was 3-5h, and after the reaction was completed, a self-repairing performance enhancer was obtained.

[0015] Preferably, the mass fraction of the curing agent is 1-3% of the total mass of the polyurethane prepolymer.

[0016] Preferably, (1) Synthesis of polyurethane prepolymer: 4,4-diphenylmethane diisocyanate, polyether diol, and catalyst cobalt succinate are placed in a high-speed disperser in proportion and mixed evenly. The reaction temperature is controlled at 80-120°C and the reaction time is 4-6 hours to obtain a polyurethane prepolymer. (2) Addition of high temperature resistant modified monomer: After the polyurethane prepolymer reaction is completed, add fluorinated vinyl acrylate and mix evenly in a high-speed disperser. Control the reaction temperature to 80-120°C and the reaction time to 1-2h. (3) Addition of cross-linking enhancing monomer: Add the cross-linking agent 1,2-cyclohexene-4,5-dione to the product obtained in step (2), place it in a high-speed disperser and mix it evenly, control the reaction temperature to 100-120°C, and stir the reaction time for 1-2 hours.

[0017] (4) Adding nanoporous glass powder: Add modified nanoporous glass powder to the product obtained in step (3), and mix uniformly in a high-speed disperser; (5) Adding a self-repairing performance enhancer: adding a self-repairing performance enhancer to the product obtained in step (4), placing the mixture in a high-speed disperser and mixing the mixture uniformly; (6) Addition of curing agent: Add dimethyl tetrazolidine as a thermal curing agent and mix evenly in a high-speed disperser to obtain the final polyurethane resin for thermal transfer.

[0018] (7) Base film layer: The polyurethane resin of the above formula is used for coating, with a coating thickness of 20-40 μm, and the coating method is reverse roller coating. After coating, preheating treatment is performed, and the temperature is controlled at 80-100 ° C. The treatment time is 2-6 minutes; (8) Release layer: A release coating layer containing a silicone resin is applied on the base film layer. The silicone resin is dimethylsiloxane, and the addition amount is 4-6% of the total weight. The coating thickness is 2-6 μm. After coating, heat treatment is performed at a temperature of 80-120°C for 2-4 minutes.

[0019] Compared with the prior art, the advantages of the present invention are: (1) Performance improvement of polyurethane resin: Improved high temperature resistance: By adding fluorinated monomers (such as fluorinated vinyl acrylate), the high temperature resistance of the polyurethane resin is enhanced, which can remain stable during high temperature transfer, avoid softening or deformation of the material, and improve the durability and reliability of the transfer film.

[0020] Enhanced cross-linking: Cross-linking enhancing monomers (such as 1,2-cyclohexene-4,5-dione) can promote cross-linking between polyurethane resin molecular chains, significantly improving its thermal stability and mechanical strength, so that the thermal transfer film can still maintain excellent mechanical properties at high temperatures.

[0021] (2) Use of modified nanoporous glass powder: Improved dispersibility: γ-aminopropyltriethoxysilane reacts chemically with the silicate groups on the surface of the glass powder through its amino group (-NH2) to form Si-O-Si bonds and Si-OC bonds. This reaction attaches the silane molecules to the surface of the glass powder, providing an organic chemical bond connection to improve the compatibility of the glass powder with the polyurethane resin; surfactants (such as Tween 80) change the hydrophilicity and lipophilicity of the powder surface, reduce the surface tension between the powder and the solvent, promote the uniform dispersion of the glass powder in the solvent, and avoid its agglomeration and precipitation; cross-linking agents (such as 1,6-hexamethylene diisocyanate) react with functional groups such as amino and hydroxyl groups in the polyurethane matrix to form a cross-linked network structure, which can enhance the adhesion and dispersibility between the microporous glass powder and the polyurethane matrix, thereby ensuring the uniformity and stability of the final thermal transfer film.

[0022] Improve the mechanical properties of the film material: The modified microporous glass powder not only enhances the mechanical properties of the resin, but also improves the hardness, toughness and impact resistance of the film material, making the thermal transfer film more durable and stable during use.

[0023] (3) Self-repair function: Enhanced self-healing properties: By introducing a self-healing enhancer combining bio-based polyester and polyurethane prepolymer, the carboxyl groups of the bio-based polyester form hydrogen bonds with the isocyanate groups of the polyurethane prepolymer, forming a reversible chemical bond network. This allows the resin to self-heal from stress-induced microcracks during the thermal transfer process when heated at 60-90°C. This innovative design significantly improves the lifespan and wear resistance of the thermal transfer film, especially under high-frequency use or high-load conditions. It can extend the film's lifespan and reduce maintenance and replacement frequency.

[0024] Green and environmentally friendly: The self-healing performance enhancer uses bio-based polyester (such as polyester extracted from soybean oil). This material is not only environmentally friendly, but also can effectively reduce the use of petroleum-based chemicals, which is in line with the trend of environmental protection and sustainable development.

[0025] (4) Enhanced transfer effect: Better thermal transfer performance: The polyurethane resin formula in this patent optimizes the adhesion and clarity of the pattern during the thermal transfer process, can maintain good transfer effects at high temperatures, and avoids the phenomenon of blurred or incomplete pattern transfer due to excessive or insufficient heat. In addition, the porous structure of the microporous glass powder can enhance the adsorption capacity of the transfer ink and optimize the heat conduction efficiency, thereby improving the transfer effect.

[0026] Higher surface finish: Due to the use of modified microporous glass powder, the material forms a uniform structure on the surface of the thermal transfer film, making the transferred pattern more delicate and clear, and improving the appearance of the final product.

[0027] (5) Good solvent tolerance and wear resistance: Improve wear resistance and anti-aging properties: The cross-linking enhancement of polyurethane resin and the addition of nano-scale microporous glass powder not only improve the thermal stability of the thermal transfer film, but also improve its wear resistance and anti-aging ability, ensuring that the thermal transfer film can maintain a good condition for a long time during multiple uses.

[0028] Excellent chemical resistance: The added cross-linker and high-temperature resistant modified monomer can enhance the polyurethane resin's resistance to solvents and chemicals, avoiding membrane material degradation caused by contact with solvents or external chemicals.

[0029] (6) Simplification of production process and improvement of efficiency: Process Controllability and Stability: This thermal transfer film's production process utilizes a specific curing agent (dimethyltetrazolidinyl) for heat curing, ensuring high controllability and stability during production. The reaction temperature and time are precisely controlled at each step, minimizing potential deviations during production and improving efficiency and product consistency.

[0030] Online coating technology: Using online coating technology to apply polyurethane resin to the substrate can achieve continuous production, reduce production costs, and ensure the uniformity of the coating and precise control of film thickness.

[0031] (7) Advantages of multi-layer coating system: Multi-layer coating structure: Through the design of a multi-layer coating system, the combination of base film layer and release layer effectively improves the overall performance of thermal transfer film. The base film layer ensures excellent pattern transfer performance, while the release layer effectively prevents adhesion between the film material and the substrate during the thermal transfer process, improving the film material's operability and production efficiency. DETAILED DESCRIPTION

[0032] Example 1: (1) Synthesis of polyurethane prepolymer: 100 g of 4,4-diphenylmethane diisocyanate, 800 g of polyether diol, and 1 g of catalyst cobalt succinate were placed in a high-speed disperser and mixed evenly. The molecular weight of the polyether diol was 2000. The reaction temperature was controlled at 80 °C and the reaction time was 4 h to obtain a polyurethane prepolymer. (2) Addition of high temperature resistant modified monomer: After the polyurethane prepolymer reaction is completed, add fluorinated vinyl acrylate, the mass of which is 2% of the total mass of the polyurethane prepolymer, place it in a high-speed disperser and mix it evenly. Control the reaction temperature to 80 ° C and the reaction time to 1 h; (3) Addition of cross-linking enhancing monomer: Add the cross-linking agent 1,2-cyclohexene-4,5-dione to the product obtained in step (2) in an amount of 1% by mass based on the total mass of the polyurethane prepolymer, place the mixture in a high-speed disperser and mix evenly. Control the reaction temperature to be 100°C and the stirring reaction time to be 1 hour.

[0033] (4) Addition of nano-scale microporous glass powder: Add modified nano-scale microporous glass powder to the product obtained in step (3), the mass fraction of which is 4% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The particle size of the microporous glass powder is 40 nm, and the specific surface area of ​​the microporous glass powder is 200 m 2 / g, the preparation method of the modified nano-porous glass powder is as follows: the nano-porous glass powder is washed with deionized water and dried, and then 30g of anhydrous ethanol solvent and 10g of nano-porous glass powder are placed in a reaction container, ultrasonically dispersed evenly, 0.1g of γ-aminopropyltriethoxysilane is added, ultrasonically dispersed evenly, stirred and reacted at 50°C for 2h, and then 0.01g of surfactant Tween 80 is added, ultrasonically dispersed evenly, and then 0.06g of 1,6-hexamethylene diisocyanate is added, ultrasonically dispersed evenly, stirred and reacted at 70°C for 2h, centrifuged, washed with anhydrous ethanol and dried to obtain the modified nano-porous glass powder; (5) Addition of self-repairing performance enhancer: Add self-repairing performance enhancer to the product obtained in step (4), the mass fraction of which is 3% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The preparation method of the self-repairing performance enhancer is as follows: 10g of 1,6-hexanediol, 42g of 1,6-hexamethylene diisocyanate and 0.1g of catalyst cobalt succinate were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 80°C, and the stirring reaction time was 4h. After the reaction was completed, a polyurethane prepolymer containing a certain proportion of isocyanate groups was obtained. 100g of soybean oil and 1g of catalyst aluminum chloride trifluoride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 160°C, and the stirring reaction time was 120 minutes. After the reaction was completed, a bio-based polyester extracted from soybean oil was obtained. 30g of bio-based polyester, 10g of polyurethane prepolymer, and 0.1g of catalyst lead tetrachloride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 70°C, and the stirring reaction time was 3h. After the reaction was completed, a self-healing performance enhancer was obtained. (6) Addition of curing agent: Add dimethyl tetrazolidine, a heat curing agent, at a mass fraction of 1% of the total mass of the polyurethane prepolymer, and mix evenly in a high-speed disperser to obtain the final polyurethane resin for thermal transfer.

[0034] (7) Base film layer: The polyurethane resin obtained in step (6) is used for coating, with a coating thickness of 20 μm, and the coating method is reverse roll coating. After coating, preheating treatment is performed, and the temperature is controlled at 80°C for 2 minutes; (8) Release layer: A release coating layer containing a silicone resin is applied on the base film layer. The silicone resin is dimethylsiloxane, and the addition amount is 4% of the total weight. The coating thickness is 2 μm. After coating, heat treatment is performed at a temperature of 80°C and a treatment time of 2 minutes.

[0035] Example 2: (1) Synthesis of polyurethane prepolymer: 100 g of 4,4-diphenylmethane diisocyanate, 1000 g of polyether diol, and 1.5 g of catalyst cobalt succinate were placed in a high-speed disperser and mixed evenly. The molecular weight of the polyether diol was 2500. The reaction temperature was controlled at 90 °C and the reaction time was 4.5 h to obtain a polyurethane prepolymer. (2) Addition of high temperature resistant modified monomer: After the polyurethane prepolymer reaction is completed, add fluorinated vinyl acrylate, the mass fraction of which is 2.5% of the total mass of the polyurethane prepolymer, place it in a high-speed disperser and mix it evenly. Control the reaction temperature to 90 ° C and the reaction time to 1.25 h; (3) Addition of cross-linking enhancing monomer: Add the cross-linking agent 1,2-cyclohexene-4,5-dione to the product obtained in step (2) in an amount of 1.25% by mass based on the total mass of the polyurethane prepolymer, place the mixture in a high-speed disperser and mix evenly. Control the reaction temperature to be 105°C and the stirring reaction time to be 1.25 h.

[0036] (4) Addition of nano-porous glass powder: Add modified nano-porous glass powder to the product obtained in step (3), the mass fraction of which is 4.5% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The particle size of the microporous glass powder is 55 nm, and the specific surface area of ​​the microporous glass powder is 240 m 2 / g, the preparation method of the modified nano-porous glass powder is: washing the nano-porous glass powder with deionized water and drying it, then placing 35g of anhydrous ethanol solvent and 10g of the nano-porous glass powder in a reaction container, ultrasonically dispersing them uniformly, adding 0.15g of γ-aminopropyltriethoxysilane, ultrasonically dispersing them uniformly, stirring and reacting at 55°C for 2.5h, then adding 0.015g of surfactant Tween 80, ultrasonically dispersing them uniformly, then adding 0.07g of 1,6-hexamethylene diisocyanate, ultrasonically dispersing them uniformly, stirring and reacting at 75°C for 2.5h, centrifuging, washing with anhydrous ethanol and drying to obtain the modified nano-porous glass powder; (5) Addition of self-repairing performance enhancer: Add self-repairing performance enhancer to the product obtained in step (4), the mass fraction of which is 3.5% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The preparation method of the self-repairing performance enhancer is as follows: 10g of 1,6-hexanediol, 49g of 1,6-hexamethylene diisocyanate and 0.15g of catalyst cobalt succinate were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 90°C, and the stirring reaction time was 4.5h. After the reaction was completed, a polyurethane prepolymer containing a certain proportion of isocyanate groups was obtained. 100g of soybean oil and 1.5g of catalyst aluminum chloride trifluoride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 165°C, and the stirring reaction time was 135 minutes. After the reaction was completed, a bio-based polyester extracted from soybean oil was obtained. 35g of bio-based polyester, 10g of polyurethane prepolymer, and 0.15g of catalyst lead tetrachloride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 75°C, and the stirring reaction time was 3.5h. After the reaction was completed, a self-healing performance enhancer was obtained; (6) Addition of curing agent: Add dimethyl tetrazolidine, a heat curing agent, at a mass fraction of 1.5% of the total mass of the polyurethane prepolymer, and mix evenly in a high-speed disperser to obtain the final polyurethane resin for thermal transfer.

[0037] (7) Base film layer: The polyurethane resin obtained in step (6) is used for coating, with a coating thickness of 25 μm, and the coating method is reverse roll coating. After coating, preheating treatment is performed, and the temperature is controlled at 85°C for 3 minutes; (8) Release layer: A release coating layer containing a silicone resin is applied on the base film layer. The silicone resin is dimethylsiloxane, and the addition amount is 4.5% of the total weight. The coating thickness is 3 μm. After coating, heat treatment is performed at a temperature of 90°C and a treatment time of 2.5 minutes.

[0038] Example 3: (1) Synthesis of polyurethane prepolymer: 100 g of 4,4-diphenylmethane diisocyanate, 1200 g of polyether diol, and 2 g of catalyst cobalt succinate were placed in a high-speed disperser and mixed evenly. The molecular weight of the polyether diol was 3000. The reaction temperature was controlled at 100 °C and the reaction time was 5 h to obtain a polyurethane prepolymer. (2) Addition of high temperature resistant modified monomer: After the polyurethane prepolymer reaction is completed, add fluorinated vinyl acrylate, the mass of which is 3% of the total mass of the polyurethane prepolymer, place it in a high-speed disperser and mix it evenly. Control the reaction temperature to 100 ° C and the reaction time to 1.5 h; (3) Addition of cross-linking enhancing monomer: Add the cross-linking agent 1,2-cyclohexene-4,5-dione to the product obtained in step (2) in an amount of 1.5% by mass based on the total mass of the polyurethane prepolymer, place the mixture in a high-speed disperser and mix evenly. Control the reaction temperature to be 110°C and the stirring reaction time to be 1.5 h.

[0039] (4) Addition of nano-porous glass powder: Add modified nano-porous glass powder to the product obtained in step (3), the mass of which is 5% of the total mass of the polyurethane prepolymer, and mix it in a high-speed disperser until it is evenly mixed. The particle size of the microporous glass powder is 70nm, and the specific surface area of ​​the microporous glass powder is 280m 2 / g, the preparation method of the modified nano-porous glass powder is as follows: the nano-porous glass powder is washed with deionized water and dried, and then 40g of anhydrous ethanol solvent and 10g of nano-porous glass powder are placed in a reaction container, ultrasonically dispersed evenly, 0.2g of γ-aminopropyltriethoxysilane is added, ultrasonically dispersed evenly, stirred and reacted at 60°C for 3h, and then 0.02g of surfactant Tween 80 is added, ultrasonically dispersed evenly, and then 0.08g of 1,6-hexamethylene diisocyanate is added, ultrasonically dispersed evenly, stirred and reacted at 80°C for 3h, centrifuged, washed with anhydrous ethanol and dried to obtain the modified nano-porous glass powder; (5) Addition of self-repairing performance enhancer: Add self-repairing performance enhancer to the product obtained in step (4), the mass fraction of which is 4% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The preparation method of the self-repairing performance enhancer is as follows: 10g of 1,6-hexanediol, 56g of 1,6-hexamethylene diisocyanate and 0.2g of catalyst cobalt succinate were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 100°C, and the stirring reaction time was 5h. After the reaction was completed, a polyurethane prepolymer containing a certain proportion of isocyanate groups was obtained. 100g of soybean oil and 2g of catalyst aluminum chloride trifluoride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 170°C, and the stirring reaction time was 150 minutes. After the reaction was completed, a bio-based polyester extracted from soybean oil was obtained. 10g of bio-based polyester, 10g of polyurethane prepolymer, and 0.2g of catalyst lead tetrachloride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 80°C, and the stirring reaction time was 4h. After the reaction was completed, a self-healing performance enhancer was obtained. (6) Addition of curing agent: Add dimethyl tetrazolidine, a heat curing agent, at a mass fraction of 2% of the total mass of the polyurethane prepolymer, and mix evenly in a high-speed disperser to obtain the final polyurethane resin for thermal transfer.

[0040] (7) Base film layer: The polyurethane resin obtained in step (6) is used for coating, with a coating thickness of 30 μm, and the coating method is reverse roll coating. After coating, preheating treatment is performed, and the temperature is controlled at 90°C for 4 minutes; (8) Release layer: A release coating layer containing a silicone resin is applied on the base film layer. The silicone resin is dimethylsiloxane, and the addition amount is 5% of the total weight. The coating thickness is 4 μm. After coating, heat treatment is performed at a temperature of 100°C and a treatment time of 3 minutes.

[0041] Example 4: (1) Synthesis of polyurethane prepolymer: 100 g of 4,4-diphenylmethane diisocyanate, 1400 g of polyether diol, and 2.5 g of catalyst cobalt succinate were placed in a high-speed disperser and mixed evenly. The molecular weight of the polyether diol was 3500. The reaction temperature was controlled at 110 °C and the reaction time was 5.5 h to obtain a polyurethane prepolymer. (2) Addition of high temperature resistant modified monomer: After the polyurethane prepolymer reaction is completed, add fluorinated vinyl acrylate, the mass of which is 3.5% of the total mass of the polyurethane prepolymer, place it in a high-speed disperser and mix it evenly. Control the reaction temperature to 110 ° C and the reaction time to 1.75 h; (3) Addition of cross-linking enhancing monomer: Add the cross-linking agent 1,2-cyclohexene-4,5-dione to the product obtained in step (2) in an amount of 1.75% by mass based on the total mass of the polyurethane prepolymer, place the mixture in a high-speed disperser and mix evenly. Control the reaction temperature to be 110°C and the stirring reaction time to be 1.75 h.

[0042] (4) Addition of nano-porous glass powder: Add modified nano-porous glass powder to the product obtained in step (3), the mass fraction of which is 5.5% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The particle size of the microporous glass powder is 85 nm, and the specific surface area of ​​the microporous glass powder is 320 m 2 / g, the preparation method of the modified nano-porous glass powder is: washing the nano-porous glass powder with deionized water and drying it, then placing 45g of anhydrous ethanol solvent and 10g of the nano-porous glass powder in a reaction container, ultrasonically dispersing them uniformly, adding 0.25g of γ-aminopropyltriethoxysilane, ultrasonically dispersing them uniformly, stirring and reacting at 65°C for 3.5h, then adding 0.025g of surfactant Tween 80, ultrasonically dispersing them uniformly, then adding 0.09g of 1,6-hexamethylene diisocyanate, ultrasonically dispersing them uniformly, stirring and reacting at 85°C for 3.5h, centrifuging, washing with anhydrous ethanol and drying to obtain the modified nano-porous glass powder; (5) Addition of self-repairing performance enhancer: Add self-repairing performance enhancer to the product obtained in step (4), the mass fraction of which is 4.5% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The preparation method of the self-repairing performance enhancer is as follows: 10g of 1,6-hexanediol, 63g of 1,6-hexamethylene diisocyanate and 0.25g of catalyst cobalt succinate were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 110°C, and the stirring reaction time was 5.5h. After the reaction was completed, a polyurethane prepolymer containing a certain proportion of isocyanate groups was obtained. 100g of soybean oil and 2.5g of catalyst aluminum trifluorochloride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 175°C, and the stirring reaction time was 165 minutes. After the reaction was completed, a bio-based polyester extracted from soybean oil was obtained. 45g of bio-based polyester, 10g of polyurethane prepolymer, and 0.25g of catalyst lead tetrachloride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 85°C, and the stirring reaction time was 4.5h. After the reaction was completed, a self-healing performance enhancer was obtained; (6) Addition of curing agent: Add dimethyl tetrazolidine, a heat curing agent, at a mass fraction of 2.5% of the total mass of the polyurethane prepolymer, and mix evenly in a high-speed disperser to obtain the final polyurethane resin for thermal transfer.

[0043] (7) Base film layer: The polyurethane resin obtained in step (6) is used for coating, with a coating thickness of 35 μm, and the coating method is reverse roll coating. After coating, preheating treatment is performed, and the temperature is controlled at 95°C for 5 minutes; (8) Release layer: A release coating layer containing a silicone resin is applied on the base film layer. The silicone resin is dimethylsiloxane, and the addition amount is 5.5% of the total weight. The coating thickness is 5 μm. After coating, heat treatment is performed at a temperature of 110°C and a treatment time of 3.5 minutes.

[0044] Example 5: (1) Synthesis of polyurethane prepolymer: 100 g of 4,4-diphenylmethane diisocyanate, 1600 g of polyether diol, and 3 g of catalyst cobalt succinate were placed in a high-speed disperser and mixed evenly. The molecular weight of the polyether diol was 4000. The reaction temperature was controlled at 120 °C and the reaction time was 6 h to obtain a polyurethane prepolymer. (2) Addition of high temperature resistant modified monomer: After the polyurethane prepolymer reaction is completed, add fluorinated vinyl acrylate, the mass of which is 4% of the total mass of the polyurethane prepolymer, place it in a high-speed disperser and mix it evenly. Control the reaction temperature to 120 ° C and the reaction time to 2 h; (3) Addition of cross-linking enhancing monomer: Add the cross-linking agent 1,2-cyclohexene-4,5-dione to the product obtained in step (2), the mass fraction of which is 2% of the total mass of the polyurethane prepolymer, place it in a high-speed disperser and mix it evenly, control the reaction temperature to 120°C, and stir the reaction time for 2 hours.

[0045] (4) Addition of nano-porous glass powder: Add modified nano-porous glass powder to the product obtained in step (3), the mass fraction of which is 6% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The particle size of the microporous glass powder is 100 nm, and the specific surface area of ​​the microporous glass powder is 360 m 2 / g, the preparation method of the modified nano-porous glass powder is as follows: the nano-porous glass powder is washed with deionized water and dried, and then 50g of anhydrous ethanol solvent and 10g of nano-porous glass powder are placed in a reaction container, ultrasonically dispersed evenly, 0.3g of γ-aminopropyltriethoxysilane is added, ultrasonically dispersed evenly, stirred and reacted at 70°C for 4h, and then 0.03g of surfactant Tween 80 is added, ultrasonically dispersed evenly, and then 0.1g of 1,6-hexamethylene diisocyanate is added, ultrasonically dispersed evenly, stirred and reacted at 90°C for 4h, centrifuged, washed with anhydrous ethanol and dried to obtain the modified nano-porous glass powder; (5) Addition of self-repairing performance enhancer: Add self-repairing performance enhancer to the product obtained in step (4), the mass fraction of which is 5% of the total mass of the polyurethane prepolymer, and mix them evenly in a high-speed disperser. The preparation method of the self-repairing performance enhancer is as follows: 10g of 1,6-hexanediol, 70g of 1,6-hexamethylene diisocyanate and 0.3g of catalyst cobalt succinate were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 120°C, and the stirring reaction time was 6h. After the reaction was completed, a polyurethane prepolymer containing a certain proportion of isocyanate groups was obtained. 100g of soybean oil and 3g of catalyst aluminum trifluorochloride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 180°C, and the stirring reaction time was 180 minutes. After the reaction was completed, a bio-based polyester extracted from soybean oil was obtained. 50g of bio-based polyester, 10g of polyurethane prepolymer, and 0.3g of catalyst lead tetrachloride were added to a reaction vessel, placed in a high-speed disperser and mixed evenly, the temperature was controlled at 90°C, and the stirring reaction time was 5h. After the reaction was completed, a self-healing performance enhancer was obtained. (6) Addition of curing agent: Add dimethyl tetrazolidine, a heat curing agent, at a mass fraction of 3% of the total mass of the polyurethane prepolymer, and mix evenly in a high-speed disperser to obtain the final polyurethane resin for thermal transfer.

[0046] (7) Base film layer: The polyurethane resin obtained in step (6) is used for coating, with a coating thickness of 40 μm, and the coating method is reverse roll coating. After coating, preheating treatment is performed, and the temperature is controlled at 100°C for 6 minutes; (8) Release layer: A release coating layer containing a silicone resin is applied on the base film layer. The silicone resin is dimethylsiloxane, and the addition amount is 6% of the total weight. The coating thickness is 6 μm. After coating, heat treatment is performed at a temperature of 120°C and a treatment time of 4 minutes.

[0047] Performance Testing Thermal stability test 10 mg of the thermal transfer film obtained in Examples 1-5 was taken and subjected to a thermal stability test using a TA Instruments Q50 thermogravimetric analyzer. The test was conducted in a nitrogen atmosphere at a flow rate of 20 mL / min, a preheating time of 30 minutes, and a heating rate of 10°C / min from room temperature to 800°C. The following table shows the test results: Mechanical properties testing (tensile strength and elongation at break) The thermal transfer film products obtained in Examples 1-5 were prepared into standard tensile specimens measuring 150 mm × 25 mm. Mechanical properties (tensile strength and elongation at break) were tested using an Instron 5982 electronic universal testing machine at room temperature and a tensile rate of 50 mm / min. The test results are shown in the following table: Self-repair performance test The thermal transfer film products obtained in Examples 1-5 were prepared into 50 mm × 50 mm specimens. Pressure was applied to the specimens using a LABPRESS 2000 hot press tester, and a pressure of 400 N was applied for stretching. The specimens were then heated to 60-90°C and maintained at the repair temperature for 5-9 minutes. The repaired microcracks were observed using a microscope, and the crack closure status was recorded. The test results are shown in the following table: Wear resistance test The thermal transfer film products obtained in Examples 1-5 were prepared into circular samples with a diameter of 50 mm. The abrasion resistance of the samples was tested using a TaberAbraser 5150 abrasion tester. The test wheel was an H-22 abrasive wheel, the load was 500 g, and the number of rotations was 500. The test results are shown in the following table: Transfer effect test (transfer quality and adhesion) The thermal transfer film products obtained in Examples 1-5 were transferred using a Grafix 4800 thermal transfer machine at a temperature of 150° C. for 30 seconds. The clarity and adhesion of the pattern after transfer were measured. The following table shows the test results:

Claims

1. A polyurethane resin for thermal transfer, a preparation method thereof, and a thermal transfer film, characterized in that: The composition of the polyurethane resin includes: (1) Polyurethane prepolymer: obtained by the reaction of isocyanate monomer and polyol under the promotion of cobalt succinate catalyst, wherein the isocyanate is 4,4-diphenylmethane diisocyanate and the polyol is polyether diol with a molecular weight of 2000-4000; (2) High temperature resistant modified monomer: fluorinated monomer, wherein the fluorinated monomer is fluorinated vinyl acrylate; (3) a cross-linking enhancing monomer: a cross-linking agent selected from β-ketone compounds, wherein the cross-linking agent is 1,2-cyclohexene-4,5-dione; (4) Nano-scale microporous glass powder: The particle size of the microporous glass powder is 40-100 nm, and the specific surface area of ​​the microporous glass powder is 200-360 m 2 / g, the compatibility of the microporous glass powder with the polyurethane resin is enhanced by surface modification; (5) Self-repairing performance enhancer: Combining bio-based polyester and polyurethane prepolymer, the self-repairing performance enhancer is designed with a reversible chemical bond network, so that the microcracks generated by stress in the resin during the thermal transfer process can be repaired by heating. The self-repairing temperature is 60-90°C and the repair time is 5-9 minutes; (6) Curing agent: Add a thermal curing agent, wherein the thermal curing agent is dimethyl tetrazolidine.

2. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The mass ratio of the isocyanate, the polyol and the catalyst cobalt succinate is 1:8-16:0.01-0.

03.

3. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The mass fraction of the high temperature resistant modified monomer is 2-4% of the total mass of the polyurethane prepolymer.

4. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The mass fraction of the cross-linking reinforcing monomer is 1-2% of the total mass of the polyurethane prepolymer.

5. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The mass fraction of the nano-scale microporous glass powder is 4-6% of the total mass of the polyurethane prepolymer.

6. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The surface modification method of the nano-scale microporous glass powder comprises the following steps: washing the nano-scale microporous glass powder with deionized water and drying it, then placing anhydrous ethanol solvent and the nano-scale microporous glass powder in a reaction container, uniformly dispersing them by ultrasonication, adding γ-aminopropyltriethoxysilane, uniformly dispersing them by ultrasonication, stirring and reacting at 50-70°C for 2-4 hours, then adding a surfactant Tween 80, uniformly dispersing them by ultrasonication, and then adding 1,6-hexamethylene diisocyanate in a mass ratio of 30-50:10:0.1-0.3:0.01-0.03:0.06-0.1, uniformly dispersing them by ultrasonication, stirring and reacting at 70-90°C for 2-4 hours, centrifuging, washing with anhydrous ethanol, and drying to obtain the modified nano-scale microporous glass powder.

7. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The mass fraction of the self-repairing performance enhancer is 3-5% of the total mass of the polyurethane prepolymer.

8. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The preparation method of the self-repairing performance enhancer is as follows: 1,6-hexanediol, 1,6-hexamethylene diisocyanate, and catalyst cobalt succinate are added to a reaction container in a mass ratio of 1:4.2-7:0.01-0.03, placed in a high-speed disperser and mixed evenly, the temperature is controlled at 80-120°C, the stirring reaction time is 4-6 hours, and after the reaction is completed, a polyurethane prepolymer containing a certain proportion of isocyanate groups is obtained, soybean oil and catalyst aluminum chloride are added in a mass ratio of 1:0.01-0.

03. The example is added into a reaction container, placed in a high-speed disperser and mixed evenly, the temperature is controlled at 160-180°C, the stirring reaction time is 120-180 minutes, and after the reaction is completed, a bio-based polyester extracted from soybean oil is obtained, which is added into a reaction container with a polyurethane prepolymer and a catalyst lead tetrachloride in a mass ratio of 3-5:1:0.01-0.03, placed in a high-speed disperser and mixed evenly, the temperature is controlled at 70-90°C, the stirring reaction time is 3-5h, and after the reaction is completed, a self-healing performance enhancer is obtained.

9. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: The mass fraction of the curing agent is 1-3% of the total mass of the polyurethane prepolymer.

10. The polyurethane resin for thermal transfer, its preparation method, and thermal transfer film according to claim 1, characterized in that: (1) Synthesis of polyurethane prepolymer: 4,4-diphenylmethane diisocyanate, polyether diol, and catalyst cobalt succinate are placed in a high-speed disperser in proportion and mixed evenly. The reaction temperature is controlled at 80-120°C and the reaction time is 4-6 hours to obtain a polyurethane prepolymer. (2) Addition of high temperature resistant modified monomer: After the polyurethane prepolymer reaction is completed, add fluorinated vinyl acrylate and mix evenly in a high-speed disperser. Control the reaction temperature to 80-120°C and the reaction time to 1-2h. (3) Addition of cross-linking enhancing monomer: add cross-linking agent 1,2-cyclohexene-4,5-dione to the product obtained in step (2), place in a high-speed disperser and mix evenly, control the reaction temperature to 100-120°C, and stir the reaction time for 1-2h; (4) Adding nanoporous glass powder: Add modified nanoporous glass powder to the product obtained in step (3), and mix uniformly in a high-speed disperser; (5) Adding a self-repairing performance enhancer: adding a self-repairing performance enhancer to the product obtained in step (4), placing the mixture in a high-speed disperser and mixing the mixture uniformly; (6) Adding a curing agent: Add dimethyl tetrazolidine as a thermal curing agent and mix evenly in a high-speed disperser to obtain the final polyurethane resin for thermal transfer; (7) Base film layer: The polyurethane resin of the above formula is used for coating, with a coating thickness of 20-40 μm, and the coating method is reverse roller coating. After coating, preheating treatment is performed, and the temperature is controlled at 80-100 ° C. The treatment time is 2-6 minutes; (8) Release layer: A release coating layer containing a silicone resin is applied on the base film layer. The silicone resin is dimethylsiloxane, and the addition amount is 4-6% of the total weight. The coating thickness is 2-6 μm. After coating, heat treatment is performed at a temperature of 80-120°C for 2-4 minutes.

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