Water-based silicon-containing hot melt adhesive applied to heat transfer printing

Abstract

The invention belongs to the technical field of heat transfer printing, and discloses a water-based silicon-containing hot melt adhesive applied to heat transfer printing, the water-based silicon-containing hot melt adhesive is a water-based polyurethane resin polymerization system formed on the basis of polymerization of a polyurethane preform, and dihydroxyl-terminated polysiloxane and hot melt powder are introduced into the polymerization system, so that the water resistance, temperature resistance and weather resistance of the hot melt adhesive are improved; a hot melt adhesive layer formed by the application has higher washing fastness, and can pass a strong washing test at 60 DEG C for more than 10 hours; besides, the hot melt adhesive layer formed during application has good affinity with silica gel ink, so that the hot melt adhesive layer and the silica gel ink layer can be tightly combined without layering, the hot melt adhesive layer and the textile can also be stably combined, and the hot melt adhesive can be well applied to thermal transfer printing of the textile. The environment-friendly paint meets the environment-friendly requirement and also has good water resistance, temperature resistance and weather resistance.

Description

Technical Field

[0001] This invention belongs to the field of thermal transfer technology, specifically relating to a water-based silicone hot melt adhesive used in thermal transfer. Background Technology

[0002] Due to its advantages such as high efficiency, strong circulation and diverse effects, heat transfer printing has become the mainstream technology for processing clothing labels. Heat transfer labels are usually composed of release film, printing ink layer and hot melt adhesive layer. Among them, the hot melt adhesive layer is particularly important, as it is related to the adhesion between the label and the clothing substrate.

[0003] Currently, most hot melt adhesive layers are formed using oil-based hot melt adhesives. This is because oil-based hot melt adhesives have significantly better water resistance, high temperature resistance, and weather resistance than water-based hot melt adhesives. Labels made with oil-based hot melt adhesives have good wash fastness and weather resistance, and the printing ink layer is difficult to separate from the hot melt adhesive layer. However, oil-based hot melt adhesives have very obvious environmental drawbacks. They are usually made with highly polar solvents, which have a strong pungent odor, are highly toxic, and are harmful to the human body. In particular, when heat transfer labels are printed on textiles, the oil-based hot melt adhesives need to be baked at high temperatures to form the hot melt adhesive layer. During this process, the highly polar solvents evaporate into the environment, resulting in VOC emissions that seriously exceed the standards, affecting human and environmental safety. While water-based hot melt adhesives do not release toxic organic solvents, their water resistance, high temperature resistance, and weather resistance are poor. As a result, heat transfer labels made from them cannot pass the high-temperature washing test above 40°C, and the resulting heat transfer labels have poor wash fastness. Therefore, water-based hot melt adhesives have not been widely used in the field of heat transfer printing.

[0004] In the printing field, silicone inks for printing possess excellent safety, temperature resistance, weather resistance, high elasticity, and good resilience, enabling them to be printed and adhered well to textiles to form a heat transfer label. This typically consists of a release film, a silicone ink layer, and a hot melt adhesive layer. However, conventional hot melt adhesives have low reactivity with silicone, making it difficult to bond them together; they merely adhere to each other, resulting in delamination between the silicone and hot melt adhesive layers. Over time, this delamination can occur. Water-based hot melt adhesives are even more difficult to apply to this type of heat transfer label. For example, patent CN112552856A discloses a water-based hot melt adhesive... Hot melt adhesives are environmentally friendly and have good adhesion and wash fastness, but their adhesion to silicone ink layers is not strong and their wash resistance is poor, making them unsuitable for use in the field of thermal transfer silicone. Patent CN118064097A discloses a polyurethane hot melt adhesive that improves the adhesion strength between the polyurethane hot melt adhesive and silicone-containing fabrics by adding siloxanes to the polyurethane system; however, delamination still occurs between the adhesive and the silicone ink layer, and its durability and wash fastness are not high. Therefore, it is necessary to develop a water-based hot melt adhesive for thermal transfer of silicone inks. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a water-based silicone hot melt adhesive for use in thermal transfer printing.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows: A water-based silicone-containing hot melt adhesive for heat transfer printing is composed of the following components in parts by weight: 25-30 parts polyurethane prepolymer, 5-10 parts polycaprolactone diol, 1-5 parts dihydroxyl-terminated polysiloxane, 0.03-1 part chain extender, 0.02-0.2 parts organic bismuth catalyst, 0.5-2 parts triethylamine neutralizer, 80-100 parts deionized water, 0.3-1 part emulsifier, 0.1-2 parts thickener, and 30-40 parts hot melt powder; wherein the hydroxyl value of the polycaprolactone diol is 100-120 mg / KOH / g.

[0007] The polyurethane prepolymer is an isocyanate-terminated prepolymer, with the optimal choice being WANNATE IPP-270 from Wanhua Chemical Group Co., Ltd., with an NCO content of 2-7% and a molecular weight of 2000-5000. The preferred choice for the dual-hydroxyl-terminated polysiloxane is HSiv-305 from Hoshine Silicon Industry Co., Ltd., with a viscosity of 500-1000 cp and a molecular weight of 1000-3000.

[0008] The chain extender is one or more of dimethylolpropionic acid, dimethylolbutyric acid, sodium ethylenediamine ethanesulfonate, and triethanolamine, with dimethylolpropionic acid being the most preferred.

[0009] The organic bismuth catalyst is one or more of bismuth laurate, bismuth isooctanoate, bismuth neodecanoate, bismuth naphthenate, bismuth oxide, and bismuth nitrate, with bismuth laurate being the most preferred.

[0010] The emulsifier is a nonionic emulsifier, typically one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, fatty amine polyoxyethylene ether, and alkyl alcohol amide polyoxyethylene ether.

[0011] The thickener is one or more of sodium polyacrylate, cellulose ether, and polyurethane thickener.

[0012] The hot melt powder is one or more of thermoplastic polyurethane powder, thermoplastic polyamide powder, thermoplastic copolyester powder, and ethylene / vinyl acetate copolymer powder, preferably thermoplastic polyamide powder with a particle size of 0-60 micrometers and a melting point of 80-130℃.

[0013] The preparation method of the water-based silicone-containing hot melt adhesive used in heat transfer printing is as follows: S1. Add polyurethane prepolymer, diol, and polysiloxane to the reactor, and add acetone until the polymer is completely dissolved; S2. Heat to 45℃-50℃, then add chain extender and organic bismuth catalyst, and maintain the temperature for 3-4 hours. S3. Add triethylamine and emulsifier and stir for 30 min. Then add deionized water, start high-speed dispersion and gradually add thickener. React for 1-2 h. S4. Reduced pressure distillation was performed to remove acetone and obtain a polymer emulsion. S5. Transfer the polymer emulsion to a dispersion tank, add hot melt powder, and start high-speed dispersion for 30 minutes to obtain the water-based silicone hot melt adhesive for heat transfer printing.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention is based on a waterborne polyurethane resin polymerization system formed by the polymerization of polyurethane preforms. The polymerization system incorporates double-hydroxyl-terminated polysiloxane and hot melt powder, which improves the water resistance, temperature resistance, and weather resistance of the hot melt adhesive. The hot melt adhesive layer formed by this application has high wash fastness and can pass the strong wash test at 60°C for more than 10 hours. 2. The hot melt adhesive layer formed by the present invention has good affinity with silicone ink, which allows the two layers of hot melt adhesive and silicone ink to be tightly bonded without delamination. The hot melt adhesive can also be firmly bonded to textiles, making it well applicable to heat transfer printing on textiles. 3. Compared with oil-based hot melt adhesives, this invention not only meets environmental protection requirements but also has good water resistance, temperature resistance, and weather resistance. Detailed Implementation

[0015] To further understand the invention's content, features, and effects, the following embodiments are provided.

[0016] Example 1 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, and 20g acetone to a clean 250ml three-necked flask, and stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organic bismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether AEO-5, and stir for 30 minutes. Next, add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. Add the obtained polyurethane emulsion to a 200ml beaker, add 40g of polyamide hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 micrometers, and disperse evenly with a high-speed disperser until no visible particles remain, obtaining hot melt adhesive.

[0017] Example 2 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 1g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 40g of polyamide hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 microns was added. The mixture was dispersed evenly with a high-speed disperser until no visible particles were found, thus obtaining hot melt adhesive.

[0018] Example 3 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 3g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 40g of polyamide hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 microns was added. The mixture was dispersed evenly with a high-speed disperser until no visible particles were found, thus obtaining hot melt adhesive.

[0019] Example 4 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 5g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 40g of polyamide hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 microns was added. The mixture was dispersed evenly with a high-speed disperser until no visible particles were found, thus obtaining hot melt adhesive.

[0020] Example 5 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 8g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 40g of polyamide hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 microns was added. The mixture was dispersed evenly with a high-speed disperser until no particles were visible to the naked eye, thus obtaining hot melt adhesive.

[0021] Example 6 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 5g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 20g of polyamide hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 microns was added. The mixture was dispersed evenly with a high-speed disperser until no visible particles were found, thus obtaining hot melt adhesive.

[0022] Example 7 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 5g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organic bismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation to obtain a water-based hot melt adhesive without hot melt powder.

[0023] Example 8 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 5g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 40g of polyurethane hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 micrometers was added. The mixture was dispersed evenly in a high-speed disperser until no visible particles were found, thus obtaining hot melt adhesive.

[0024] Example 9 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 5g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 40g of copolyester hot melt powder with a softening point of 105-115℃ and a particle size of 0-60 microns was added. The powder was dispersed evenly in a high-speed disperser until no visible particles were found, thus obtaining hot melt adhesive.

[0025] Example 10 Add 30g WANNATE IPP-270, 5g polycaprolactone diol, 5g hydroxyl-terminated polysiloxane (500cp viscosity), and 20g acetone to a clean 250ml three-necked flask. Stir until the polyurethane prepolymer is completely dissolved. Heat to 45℃, add 1g dihydroxypropionic acid and 0.2g organobismuth catalyst, and stir for 4 hours. Then add 2g triethylamine and 0.8g fatty alcohol polyoxyethylene ether (AEO-5), and stir for 30 minutes. Add 100g deionized water, start high-speed dispersion, and add thickener dropwise. After the thickener is added, start vacuum distillation while maintaining high-speed stirring for 1 hour. Remove acetone by vacuum distillation. The prepared polyurethane emulsion was added to a 200ml beaker, and 40g of EVA hot melt powder with a softening point of 45-55℃ and a particle size of 0-60 microns was added. The mixture was dispersed evenly in a high-speed disperser until no visible particles were found, thus obtaining hot melt adhesive.

[0026] Performance Analysis: Test Item - Wash Fastness: The hot melt adhesive prepared in Examples 1-10 was used in combination with heat transfer printing silicone to create a five-pointed star transfer label with a silicone layer of 0.5 mm thickness and a hot melt adhesive layer of 0.1 mm thickness via screen printing. The transfer label was then pressed onto a white cotton knitted fabric using a heat press machine. The heat press conditions were: temperature 160℃, pressure 3 kg, and time 20 seconds. After heat pressing, the samples were left at room temperature for 24 hours to obtain washable samples. Then, a washing test was conducted according to the national standard GB / T 8629-2017 "Test Procedures for Household Washing and Drying of Textiles". The washing conditions were: type A washing machine, 6-hour washing program, drying program A - hanging to dry, phosphate-free standard detergent 3, Class III accompanying items, and load 2 kg. The number of washes in which the transfer label curled up was recorded, and washing was stopped when 10 washes were reached.

[0027] Test Item - Minimum Peel Force of Silicone Ink Layer: Using the hot melt adhesive prepared in Examples 1-10, and our company's silicone ink TG-18, rectangular transfer labels measuring 10cm long and 1cm wide were screen-printed. Release paper was attached to the inner 2cm of one end of the rectangular transfer label, preventing adhesion within this 2cm. One end of the release paper was clamped using a tensile testing machine, and the average minimum peel force between the hot melt adhesive layer and the silicone ink layer was tested according to GB / T2781-1995 "Adhesives T-Peel Strength Test Method - Flexible Material to Flexible Material".

[0028] The data obtained from the above implementation cases are shown in Table 1.

[0029] Table 1 Performance Data of Implementation Cases

[0030] The existing water-based hot melt adhesive has similar performance to that of Example 1, with poor wash fastness and poor adhesion to the silicone ink layer. As shown in Table 1, in Examples 1 to 6, as the amount of bi-hydroxyl-terminated polysiloxane added increases, the number of washes of the prepared water-washed samples increases, the water-wash resistance becomes stronger, and the peel resistance of the silicone ink layer also becomes stronger. Compared with Example 5, Example 4 has similar water-wash resistance, but the peel resistance of the silicone ink layer in Example 5 is worse, indicating that the amount of bi-hydroxyl-terminated polysiloxane used in Example 4 is better than that in Example 5. Compared with Example 4, the test samples prepared in Example 6 have similar water-wash resistance and peel resistance, but the hot melt powder content in Example 6 is less, resulting in lower cost. Therefore, when using polyamide hot melt powder, the formulation of Example 6 is optimal.

[0031] As can be seen from Table 1, compared with Example 4, the test sample prepared by the water-based hot melt adhesive in Example 7 without hot melt powder is weaker in peel resistance than the test sample in Example 4, and much weaker in water wash resistance than the test sample in Example 4. This indicates that the addition of hot melt powder enhances the wash fastness of the water-based hot melt adhesive during application.

[0032] As shown in Table 1, compared with Examples 6, 8, 9, and 10, the water-based hot melt adhesives made with polyamide hot melt powder and copolyester hot melt powder showed better washability and peel resistance than the other water-based hot melt adhesives made with hot melt powder. Although Example 9 had better adhesion, in practical applications, the transfer adhesive made with thermoplastic polyamide powder had better hardness and resilience than the transfer adhesive made with copolyester powder. Therefore, thermoplastic polyamide powder is the optimal choice for hot melt powder.

[0033] The water-based silicone-containing hot melt adhesive of the present invention achieves the following technical effects through the synergistic effect between its components: 1. Nanoscale double-hydroxyl-terminated polysiloxane forms an interpenetrating network structure with polyurethane prepolymer, which significantly improves the flexibility and weather resistance of the adhesive film, enabling the hot melt adhesive to maintain good bonding performance even after multiple water washes.

[0034] 2. The introduction of hot melt powder forms a strong interfacial bond with the polymer matrix, improving the bonding strength and heat resistance. This allows the hot melt adhesive to bond with the silicone ink layer and the textile surface during heat transfer.

[0035] 3. Through cross-linking and interpenetration of polyurethane prepolymer and nano-sized double-hydroxyl-terminated polysiloxane, an aqueous colloidal system is formed, which meets environmental protection requirements while also having good water resistance, temperature resistance, and weather resistance.

[0036] In summary, the high-performance water-based silicone hot melt adhesive of the present invention achieves synergistic effects among its components through formulation optimization and process improvement, resulting in a product with excellent comprehensive performance. It not only solves the problems of insufficient initial tack and poor water resistance of traditional water-based hot melt adhesives, but also makes breakthrough progress in environmental performance, and has broad market application prospects.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A water-based silicone-containing hot melt adhesive for use in heat transfer printing, characterized in that, It is composed of the following components in parts by weight: 25-30 parts of polyurethane prepolymer, 5-10 parts of polycaprolactone diol, 1-5 parts of hydroxyl-terminated polysiloxane, 0.03-1 part of chain extender, 0.02-0.2 parts of organic bismuth catalyst, 0.5-2 parts of triethylamine neutralizer, 80-100 parts of deionized water, 0.3-1 part of emulsifier, 0.1-2 parts of thickener, and 30-40 parts of hot melt powder; the hydroxyl value of the polycaprolactone diol is 100-120 mg / KOH / g.

2. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that: The polyurethane prepolymer is an isocyanate-terminated prepolymer, using WANNATE IPP-270 from Wanhua Chemical Group Co., Ltd., with an NCO content of 2-7% and a molecular weight of 2000-5000.

3. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that: The double-hydroxyl-terminated polysiloxane used is HSiv-305 from Hoshine Silicon Industry Co., Ltd., with a viscosity of 500-1000cp and a molecular weight of 1000-3000.

4. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that: The chain extender is one or more of dimethylolpropionic acid, dimethylolbutyric acid, sodium ethylenediamine ethanesulfonate, and triethanolamine.

5. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that: The organic bismuth catalyst is one or more of bismuth laurate, bismuth isooctanoate, bismuth neodecanoate, bismuth naphthenate, bismuth oxide, and bismuth nitrate.

6. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that: The emulsifier is a nonionic emulsifier, typically one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, fatty amine polyoxyethylene ether, and alkyl alcohol amide polyoxyethylene ether.

7. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that: The thickener is one or more of sodium polyacrylate, cellulose ether, and polyurethane thickener.

8. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that: The hot melt powder is one or more of thermoplastic polyurethane powder, thermoplastic polyamide powder, thermoplastic copolyester powder, and ethylene / vinyl acetate copolymer powder, preferably thermoplastic polyamide powder, with a particle size of 0-60 micrometers and a melting point of 80-130℃.

9. The water-based silicone-containing hot melt adhesive for heat transfer printing according to claim 1, characterized in that... Its preparation method is as follows: S1. Add polyurethane prepolymer, diol, and polysiloxane to the reactor, and add acetone until the polymer is completely dissolved; S2. Heat to 45℃-50℃, then add chain extender and organic bismuth catalyst, and maintain the temperature for 3-4 hours. S3. Add triethylamine and emulsifier and stir for 30 min. Then add deionized water, start high-speed dispersion and gradually add thickener. React for 1-2 h. S4. Reduced pressure distillation was performed to remove acetone and obtain a polymer emulsion. S5. Transfer the polymer emulsion to a dispersion tank, add hot melt powder, and start high-speed dispersion for 30 minutes to obtain the water-based silicone hot melt adhesive for heat transfer printing.

Images