Application of water-based adhesive containing water-based polycarbonate type polyurethane in heat transfer printing

Abstract

The invention relates to application of a water-based adhesive containing water-based polycarbonate type polyurethane in heat transfer printing. The water-based adhesive is prepared from the following raw material components in parts by mass: 5 to 30 parts of water-based polycarbonate type polyurethane dispersion emulsion, 0.007 to 0.017 part of water-based flatting agent, 0.007 to 0.017 part of water-based defoaming agent and 2 to 20 parts of water, the preparation method of the water-based adhesive comprises the following steps: mixing a water-based polycarbonate type polyurethane dispersion emulsion, a water-based flatting agent, a water-based defoaming agent and water to obtain the water-based adhesive, the application of the water-based adhesive in heat transfer printing comprises the following steps: coating a base material with the water-based adhesive, and carrying out heat transfer printing on a transfer printing film on the glued base material to realize the compounding of the transfer printing film and the base material. Compared with the prior art, the adhesive force, the high-temperature resistance, the high-low temperature performance and the high-temperature and high-humidity performance are excellent.

Description

Technical Field

[0001] This invention belongs to the field of coating transfer technology, and relates to the application of a water-based polycarbonate polyurethane adhesive in heat transfer. Background Technology

[0002] Heat transfer printing is a process that transfers patterns, text, or decorative layers from a transfer film to the surface of a target substrate. It is widely used in the surface decoration of various materials such as plastics, metals, and wood. With the rapid development of industries such as consumer electronics, automotive interiors, and home decoration, the quality requirements for heat transfer printing effects are becoming increasingly stringent, especially regarding the adhesion between the transfer film and the substrate.

[0003] Currently, hot melt adhesives are commonly used as the bonding agent between the transfer film and the substrate in thermal transfer printing processes. However, traditional hot melt adhesives are prone to problems such as decreased adhesion and peeling under harsh environmental conditions such as high temperature and high humidity, affecting the product's service life and performance stability. To solve this problem, waterborne polyurethane dispersions have gradually become a research hotspot in the field of thermal transfer printing due to their excellent adhesion, weather resistance, and environmentally friendly properties.

[0004] In the prior art, patent CN109207047A proposes a super-matte, skin-like, wear-resistant waterborne coating for PVC surface decoration and its preparation method. This coating uses super-matte waterborne polyurethane emulsion and polycarbonate-type waterborne polyurethane emulsion as the main film-forming substances, and adds waterborne defoamers, waterborne leveling agents, and other additives. The resulting coating has good adhesion and water resistance. Patent CN108587351A proposes a waterborne primer coating for automotive interior water transfer printing. This coating includes components such as waterborne acrylic dispersion and waterborne polyurethane dispersion, and has good adhesion to plastic substrates and good application results.

[0005] Secondly, patent CN104403540A proposes a high-gloss waterborne modified polyurethane topcoat. This topcoat modifies waterborne polyurethane with epoxy acrylic acid, significantly enhancing its gloss and anti-corrosion properties. Patent CN109486393A proposes a high-gloss, stain-resistant, and wear-resistant waterborne coating specifically for PVC surface decoration. This coating uses polycarbonate-based waterborne polyurethane emulsion as the main film-forming substance, and adds waterborne defoamers, waterborne leveling agents, and other additives. After printing at room temperature, the curing agent in the coating undergoes a cross-linking reaction in a 150-180°C laminating tank, forming a coating with high-gloss, stain-resistant, and wear-resistant properties.

[0006] In addition, patent CN112694827A proposes a water-based UV clear varnish for hot stamping on ABS substrate. This clear varnish uses water-based polyurethane acrylate dispersion as the main resin, combined with hydroxyl-containing acrylic emulsion and self-drying water-based polyurethane dispersion to increase the overall flexibility and water resistance of the coating film. The coating film still maintains good adhesion to the hot stamping layer after being soaked in pure water and alcohol.

[0007] However, the water-based coatings mentioned in patents CN109207047A, CN104403540A, and CN109486393A are only the outermost topcoat in the composite structure of transfer film products (topcoat layer, ink layer, and transfer adhesive layer), and do not directly contact the substrate. They are not related to the transfer adhesive. Secondly, patent CN108587351A, as a water transfer primer, cannot be directly used in heat transfer. Moreover, patent CN112694827A has adhesion problems on some substrate materials.

[0008] Overall, existing waterborne coatings still have some problems in heat transfer applications: the adhesion stability of waterborne polyurethane dispersions used in existing technologies is insufficient under extreme environmental conditions (such as high temperature and high humidity environments), and peeling is prone to occur; in addition, existing waterborne coatings also have certain limitations in terms of drying speed and transfer temperature adaptability, making it difficult to meet the needs of different substrates and different transfer processes. Summary of the Invention

[0009] The purpose of this invention is to overcome at least one defect in the prior art, such as the adhesion problem between the heat transfer film and the substrate, especially the durability problem under harsh environmental conditions such as high temperature and high humidity, and to provide an application of a water-based polycarbonate polyurethane adhesive in heat transfer. This invention achieves excellent adhesion, high temperature resistance, high and low temperature performance, and high temperature and high humidity performance.

[0010] The objective of this invention can be achieved through the following technical solutions:

[0011] One of the technical solutions of the present invention is to provide an application of an aqueous polycarbonate-type polyurethane adhesive in heat transfer printing, wherein the raw materials of the aqueous adhesive include the following components in parts by weight:

[0012] The mixture contains 5-30 parts of waterborne polycarbonate-type polyurethane dispersion emulsion, 0.007-0.017 parts of waterborne leveling agent, 0.007-0.017 parts of waterborne defoamer, and 2-20 parts of water.

[0013] The preparation method of the water-based adhesive includes the following steps:

[0014] A water-based adhesive is obtained by mixing a water-based polycarbonate-type polyurethane dispersion emulsion, a water-based leveling agent, a water-based defoamer, and water.

[0015] The application of the water-based adhesive in heat transfer includes the following steps:

[0016] A water-based adhesive is applied to a substrate, and a transfer film is then thermally transferred onto the substrate after the adhesive is applied, thus achieving the bonding of the transfer film and the substrate.

[0017] Furthermore, the aqueous polycarbonate-type polyurethane dispersion emulsion uses one or more of the following: DISCO UD-4001, DISCO UD-5001, and DISCO UD-5002.

[0018] Furthermore, the aqueous polycarbonate-type polyurethane dispersion emulsion has a solid content of 30-60% and a pH value of 7-9, and the aqueous polyurethane dispersion can provide good film-forming properties and adhesion.

[0019] Furthermore, the water-based leveling agent is selected from one or more of silicone-based, acrylate-based, and fluorocarbon-modified water-based leveling agents. The addition of the water-based leveling agent can improve the leveling properties of the coating liquid on the substrate, making the coating more uniform and smooth.

[0020] Furthermore, the water-based defoamer is selected from one or more of silicone-based and polyether-based water-based defoamers. The addition of the water-based defoamer can eliminate bubbles formed during the leveling process of the coating liquid, making the coating more uniform and smooth.

[0021] Furthermore, the mixing speed is 400~600 r / min, the temperature is 10~40 ℃, and the time is 5~20 min.

[0022] Furthermore, the coating method employs a micro-gravure coating process, with a surface drying time of 60~300 s and a dry film thickness of 2~10 μm. Through the micro-gravure coating process, the dry film thickness of the adhesive layer can be precisely controlled. This thin and uniform adhesive layer thickness is beneficial to the complete transfer of the pattern and the maintenance of clarity during the subsequent heat transfer process.

[0023] Furthermore, the substrate is made of polycarbonate (PC), steel, or acrylonitrile-butadiene-styrene copolymer (ABS), and the ink coating of the transfer film is made of acrylic, polyester, or polycarbonate.

[0024] Furthermore, the heat transfer temperature is 130~200 ℃, the pressure is 2~7 bar, and the time is 1~30 s. During the heat transfer process, this temperature range allows the adhesive layer to soften sufficiently without excessive melting, ensuring that the pattern can be completely transferred to the substrate after coating. Within this temperature range, the pattern on the surface of the transfer film can fully bond with the substrate to form a strong adhesion, while maintaining the clarity and color saturation of the pattern.

[0025] Furthermore, after the transfer film is laminated with the substrate, it exhibits qualified adhesion after being placed at a maximum temperature of 110 °C for a maximum of 1000 h, demonstrating high-temperature resistance.

[0026] After the transfer film is laminated with the substrate, the adhesion is qualified after up to 16 high and low temperature cycles of -50~90 ℃, and it has high and low temperature performance.

[0027] After the transfer film is laminated with the substrate, it exhibits qualified adhesion after being placed in an environment of up to 100 ℃ and up to 98% humidity for up to 144 hours, demonstrating high temperature and high humidity performance.

[0028] As a preferred technical solution, after the transfer film is laminated with the substrate, the adhesion is qualified after being placed at 40~110 ℃ for up to 1000 h, and it has high temperature resistance.

[0029] After the transfer film is laminated with the substrate, the adhesion is qualified after being placed in an environment of 60~100 ℃ and 50~98% humidity for up to 144 hours, and it has high temperature and high humidity performance.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The waterborne polycarbonate polyurethane dispersion used in this invention contains strong polar groups such as urethane bonds and carbonate bonds that enhance adhesion. During the heat transfer process with the transfer film, it can form a dense hydrogen bond network and dipole-dipole interactions with the surface of various substrates, thereby improving wettability and adhesion and creating favorable conditions for leveling and penetration. At the same time, the polycarbonate molecular chain structure has a certain degree of flexibility. When softened by heat, this flexibility makes it easier for the molecular chain to unfold under the action of surface tension and spread to form a smooth film. In addition, the waterborne polycarbonate polyurethane dispersion used in this invention has excellent hydrolytic stability and can maintain the bonding strength for a long time in humid or hot and humid environments, avoiding the decrease in adhesion caused by material degradation.

[0032] (2) The water-based adhesive used in this invention, under the action of water-based polycarbonate polyurethane dispersion, water-based leveling agent and water-based defoamer, can flow well and penetrate into the micropores on the surface of the substrate. After curing, it forms a mechanical interlocking structure. The adhesive film formed after curing of the water-based adhesive has a unique micro-phase separation structure, which makes the adhesive film both strong and elastic. It can effectively absorb and disperse the stress generated by impact, vibration and thermal expansion and contraction, and avoid the interface peeling caused by the brittle cracking of the adhesive film. This solves the problems of decreased adhesion and peeling between the heat transfer film and the substrate under extreme environmental conditions in the prior art, and significantly improves the service life and performance stability of the product.

[0033] (3) Existing acrylic water transfer primers, used in water transfer printing processes, rely on water pressure hydrolysis to achieve pattern transfer at room temperature. The corresponding ink is a hydrolytic water transfer special film, which is suitable for water media environment and achieves short-term pattern fixation. However, it lacks high-temperature resistance design. The water-based polycarbonate heat transfer adhesive used in this invention is used in heat transfer printing processes. It completes pattern melting and fusion by heating and pressurizing. It corresponds to a heat transfer film that needs to be adapted for thermal cross-linking reaction. It has high-temperature stability, hot melt adhesion, and strong adhesion after cooling. Water transfer primers cannot be directly applied to heat transfer. Existing acrylic water transfer primers mainly rely on physical adsorption for substrates represented by polycarbonate. They lack high-temperature chemical bonding design and are prone to softening and decomposition at >80 ℃. The water-based polycarbonate heat transfer adhesive used in this invention achieves good pattern heat transfer through chemical functional group bonding and physical intercalation, interface fusion at high temperature, no decomposition, no bubbles, and no discoloration.

[0034] (4) The water-based adhesive used in this invention has excellent adhesion, hydrolysis resistance, high temperature resistance, high and low temperature performance and high temperature and high humidity performance. It has a good transfer effect, complete pattern transfer, bright color, simple process, environmental protection and non-toxicity, and is suitable for use on the surface of various decorative materials, packaging materials and functional materials. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0036] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. In the following embodiments, unless otherwise described in detail, conventional experimental methods in the art can be used.

[0037] Unless otherwise specified, the following procedures are generally performed at room temperature and atmospheric pressure.

[0038] Example:

[0039] The application of an aqueous polycarbonate-based polyurethane adhesive in heat transfer printing involves the following specific steps:

[0040] First, prepare the raw materials, by weight: 10 parts of Japanese DISEN waterborne polycarbonate polyurethane dispersion emulsion UD-4001 with 50% solid content and pH value of 8, 0.01 parts of silicone waterborne leveling agent BYK-346, 0.01 parts of silicone waterborne defoamer BYK-028, and 7 parts of deionized water.

[0041] Secondly, after accurately weighing the raw materials according to the proportion, add them to the mixing container and stir evenly at 500 r / min at room temperature of 25℃ for 10 min to obtain the water-based adhesive as the coating liquid.

[0042] Then, the coating liquid is microgravated onto the polycarbonate (PC) substrate, and the surface drying time is controlled to be 120 s to form an adhesive layer with a dry film thickness of 4 μm.

[0043] Finally, the acrylic ink-coated transfer film is transferred onto the coated polycarbonate substrate at 150 ℃ and 3 bar pressure for 5 s using a heat transfer device with the ink coating facing down, thus completing the bonding of the transfer film and the substrate.

[0044] Comparative Example 1:

[0045] The application of an aqueous polycarbonate-based polyurethane adhesive in heat transfer printing is basically the same as in the examples, except that the aqueous leveling agent is increased from 0.01 parts to 0.05 parts. The specific steps are as follows:

[0046] First, prepare the raw materials, by weight: 10 parts of Japanese DISEN waterborne polycarbonate polyurethane dispersion emulsion UD-4001 with 50% solid content and pH value of 8, 0.05 parts of silicone waterborne leveling agent BYK-346, 0.01 parts of silicone waterborne defoamer BYK-028, and 7 parts of deionized water.

[0047] Secondly, after accurately weighing the raw materials according to the proportion, add them to the mixing container and stir evenly at 500 r / min at room temperature of 25℃ for 10 min to obtain the water-based adhesive as the coating liquid.

[0048] Then, the coating liquid is microgravated onto the polycarbonate substrate, and the surface drying time is controlled to be 120 s to form an adhesive layer with a dry film thickness of 4 μm.

[0049] Finally, the acrylic ink-coated transfer film is transferred onto the coated polycarbonate substrate at 150 ℃ and 3 bar pressure for 5 s using a heat transfer device with the ink coating facing down, thus completing the bonding of the transfer film and the substrate.

[0050] Comparative Example 2:

[0051] The application of an aqueous polycarbonate-based polyurethane adhesive in heat transfer printing is basically the same as in the examples, except that the aqueous defoamer is increased from 0.01 parts to 0.05 parts. The specific steps are as follows:

[0052] First, prepare the raw materials, by weight: 10 parts of Japanese DISEN waterborne polycarbonate polyurethane dispersion emulsion UD-4001 with a solid content of 50% and a pH value of 8, 0.01 parts of silicone waterborne leveling agent BYK-346, 0.05 parts of silicone waterborne defoamer BYK-028, and 7 parts of deionized water.

[0053] Secondly, after accurately weighing the raw materials according to the proportion, add them to the mixing container and stir evenly at 500 r / min at room temperature of 25℃ for 10 min to obtain the water-based adhesive as the coating liquid.

[0054] Then, the coating liquid is microgravated onto the polycarbonate substrate, and the surface drying time is controlled to be 120 s to form an adhesive layer with a dry film thickness of 4 μm.

[0055] Finally, the acrylic ink-coated transfer film is transferred onto the coated polycarbonate substrate at 150 ℃ and 3 bar pressure for 5 s using a heat transfer device with the ink coating facing down, thus completing the bonding of the transfer film and the substrate.

[0056] Comparative Example 3:

[0057] The application of a water-based adhesive containing an acrylic polyurethane in heat transfer printing is basically the same as in the examples, except that the formulation is derived from patent CN112694827A, and the specific steps are as follows:

[0058] First, prepare the raw materials, by mass fraction: 50% DAOTAN, a 3-4 functional waterborne polyurethane acrylate dispersion. ® The product contains TW 6464 / 36WA, 15% YL-MY7518 hydroxyl acrylic emulsion from YL Chemical, 15% Uapoly 9201 self-drying waterborne polyurethane dispersion from Lian Gu Chemical, 10% deionized water, 4% film-forming aid, 3% photoinitiator, 0.7% waterborne wetting agent, 0.4% waterborne defoamer, 1.5% waterborne thickener, and 0.4% ammonia neutralizer.

[0059] Secondly, according to the preparation method of patent CN112694827A, an aqueous adhesive is obtained as a coating liquid;

[0060] Then, the coating liquid is microgravated onto the polycarbonate substrate, and the surface drying time is controlled to be 120 s to form an adhesive layer with a dry film thickness of 4 μm.

[0061] Finally, the acrylic ink-coated transfer film is transferred onto the coated polycarbonate substrate at 150 ℃ and 3 bar pressure for 5 s using a heat transfer device with the ink coating facing down, thus completing the bonding of the transfer film and the substrate.

[0062] The above-mentioned transfer film was laminated with the substrate and then subjected to the following tests or experiments, and the test or experiment results were analyzed.

[0063] Experimental example:

[0064] The above-mentioned transfer film was laminated with the substrate and tested for cross-cut adhesion, high temperature resistance, high and low temperature performance, and high temperature and high humidity performance. The test results are shown in Table 1.

[0065] Table 1. Performance of the transfer film after lamination with the substrate in the examples and comparative examples 1 and 2.

[0066] As shown in Table 1, in the examples, the surface of the transfer film after lamination with the substrate showed no defects such as orange peel or bubble spots.

[0067] Passing the cross-cut adhesion test indicates excellent adhesion.

[0068] After being placed at 105 ℃ for 500 hours, the adhesion was satisfactory, proving that it has excellent high-temperature resistance.

[0069] After 8 cycles of high and low temperature cycling at -40 to 80 ℃, the adhesion of PV1200 was satisfactory, indicating that it can maintain good adhesion even under high and low temperature cycling conditions.

[0070] After being placed in an environment of 90 ℃ and 95% humidity for 72 hours, the adhesion was qualified, indicating that it can still maintain good adhesion in high temperature and high humidity environments.

[0071] The core function of leveling agents is to reduce the surface tension of coatings, eliminate surface defects caused by uneven substrate wetting and construction marks (such as brush marks and spray fog) during the coating process, and promote the uniform spread of coatings on the film surface to form a continuous and smooth liquid film. Defoamers, on the other hand, eliminate bubbles generated by the evaporation of air and moisture mixed in during production or construction by destroying the liquid film strength of bubbles in the coating system, thus preventing bubbles from remaining in the dry film and forming pinholes and pits. The two need to form a synergistic effect of "spreading-defoaming". In the example, under the appropriate ratio, the process of leveling agents reducing surface tension will not weaken the ability of defoamers to destroy bubbles, and the presence of defoamers will not hinder the optimization of coating spreadability by leveling agents, thus laying the foundation for the formation of a smooth coating.

[0072] In Comparative Example 1, the leveling agent ratio was too high, which would excessively reduce the surface tension of the coating, resulting in an abnormal surface tension gradient. The coating would accumulate in areas with low surface energy. Excessive leveling agent would form an adsorption layer on the surface of the coating liquid film, encapsulating tiny air bubbles and weakening the contact efficiency between the defoamer and the air bubble liquid film. This would make it difficult to break the air bubbles, and ultimately leave pinholes in the dry film, damaging the surface smoothness.

[0073] In Comparative Example 2, the proportion of defoamer was too high. Its hydrophobic components would form tiny particulate impurities in the coating film. These impurities would become obstacles to the coating spread, hindering the leveling agent from promoting the uniform spread of the coating. Excessive defoamer would precipitate on the surface of the dry film, further affecting the coating smoothness and appearance of the film. Local areas with low surface tension would shrink inward to form pits.

[0074] The above reasons lead to amplification of local defects and the intrusion of water vapor into weak areas after tests such as high temperature resistance, high and low temperature resistance, and high temperature and high humidity resistance in Comparative Examples 1 and 2;

[0075] In Comparative Example 3, the adhesion of the water-based acrylic adhesive coated on the polycarbonate substrate and then laminated with an acrylic ink transfer film significantly decreased under high and low temperature cycling and high temperature and humidity environments. In contrast, the water-based polycarbonate adhesive in the examples maintained excellent adhesion. The core reason for this is the difference in interfacial compatibility between the adhesive and the polycarbonate substrate, as well as the difference in interfacial erosion effects under high temperature and humidity environments.

[0076] 1. Differences in interfacial compatibility: The molecular chain of polycarbonate substrate contains carbonate bonds, which have specific polarity and molecular structure. In the example, the resin molecular chain of the water-based polycarbonate adhesive also contains carbonate bond structural units. According to the principle of "like dissolves like," it can form molecular-level interactions (such as hydrogen bonds and van der Waals forces) with the polycarbonate substrate interface. The coating can adhere tightly to the substrate surface and form a stable interfacial bonding layer. The strong dipole interaction can effectively resist the stress caused by temperature changes. However, the resin molecular chain of the water-based acrylic adhesive in Comparative Example 3 is mainly polymerized from acrylate monomers. The molecular structure lacks carbonate bonds that match the polycarbonate substrate, and the polarity difference is large. It lacks strong dipole interaction, and its interfacial interaction with the polycarbonate substrate is weak. It can only form a physical adsorption type bond. The interfacial bonding force itself has inherent defects and will further fail under high and low temperature cycling due to thermal expansion and contraction.

[0077] 2. Differences in interfacial erosion effects under high temperature and humidity conditions: Under high temperature and humidity conditions, moisture easily penetrates to the interface between the coating and the polycarbonate substrate. For the waterborne acrylic adhesive system in Comparative Example 3, due to its weak interfacial bonding with the polycarbonate substrate, moisture easily accumulates at the interface and produces a "swell-peel" effect—moisture penetration weakens the physical adsorption force between the coating and the substrate, while high temperature accelerates molecular movement at the interface, causing the interfacial bonding layer to gradually disintegrate, ultimately leading to the peeling of the coating from the polycarbonate substrate, manifested as a decrease in adhesion. In contrast, the waterborne polycarbonate adhesive in the example has a tight interfacial bond with the polycarbonate substrate, and molecular-level interactions effectively block moisture penetration. Even under high temperature and humidity conditions, the stability of the interfacial bonding layer is not easily damaged, thus maintaining good adhesion.

[0078] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. The application of an aqueous polycarbonate-based polyurethane adhesive in heat transfer printing, characterized in that, The raw materials of the water-based adhesive include the following components in parts by weight: The mixture contains 5-30 parts of waterborne polycarbonate-type polyurethane dispersion emulsion, 0.007-0.017 parts of waterborne leveling agent, 0.007-0.017 parts of waterborne defoamer, and 2-20 parts of water. The preparation method of the water-based adhesive includes the following steps: A water-based adhesive is obtained by mixing a water-based polycarbonate-type polyurethane dispersion emulsion, a water-based leveling agent, a water-based defoamer, and water. The application of the water-based adhesive in heat transfer includes the following steps: A water-based adhesive is applied to a substrate, and a transfer film is then thermally transferred onto the substrate after the adhesive is applied, thus achieving the bonding of the transfer film and the substrate.

2. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The aqueous polycarbonate-type polyurethane dispersion emulsion uses one or more of the following: DISCO UD-4001, DISCO UD-5001, and DISCO UD-5002.

3. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The aqueous polycarbonate-type polyurethane dispersion emulsion has a solid content of 30-60% and a pH value of 7-9.

4. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The water-based leveling agent is selected from one or more of the following: organosilicon, acrylate, and fluorocarbon modified water-based leveling agents.

5. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The water-based defoamer is selected from one or more of organosilicon and polyether water-based defoamers.

6. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The mixing speed is 400~600 r / min, the temperature is 10~40 ℃, and the time is 5~20 min.

7. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The coating method employs a micro-gravure coating process, with a surface drying time of 60~300 s and a dry film thickness of 2~10 μm.

8. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The substrate is made of polycarbonate, steel, or acrylonitrile-butadiene-styrene copolymer, and the ink coating of the transfer film is made of acrylic, polyester, or polycarbonate.

9. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, The heat transfer temperature is 130~200 ℃, the pressure is 2~7 bar, and the time is 1~30 s.

10. The application of the waterborne polycarbonate-type polyurethane adhesive according to claim 1 in heat transfer printing, characterized in that, After the transfer film is laminated with the substrate, it exhibits qualified adhesion after being placed at a maximum temperature of 110 °C for a maximum of 1000 h, demonstrating high temperature resistance. After the transfer film is laminated with the substrate, the adhesion is qualified after up to 16 high and low temperature cycles of -50~90 ℃, and it has high and low temperature performance. After the transfer film is laminated with the substrate, it exhibits qualified adhesion after being placed in an environment of up to 100 ℃ and up to 98% humidity for up to 144 hours, demonstrating high temperature and high humidity performance.

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