Polyurethane hot-melt foil stamping adhesive and preparation method therefor

Abstract

The present application relates to the technical field of adhesives. Disclosed are a polyurethane hot-melt foil stamping adhesive and a preparation method therefor. The hot-melt foil stamping adhesive comprises the following raw materials: 30-45% of polyether polyol, 20-38% of polyester polyol, 3-5% of a tackifying resin, 20-30% of a diisocyanate, 0.5-1% of a chain extender, 0.1-0.5% of an antioxidant, 0.1-0.5% of an ultraviolet absorber, 2-5% of a blocking agent, 0.05-0.1% of a catalyst, and 0.05-0.1% of a de-blocking catalyst. The preparation method therefor comprises the following steps: mixing and melting polyether polyol, polyester polyol, a tackifying resin, an antioxidant and an ultraviolet absorber, performing vacuum-pumping and cooling, adding a molten diisocyanate thereto for a reaction, adding a chain extender, continuing the reaction with the vacuum degree and the temperature remaining unchanged, conducting sampling, testing the residual amount of -NCO, adding a blocking agent, continuing the reaction for a period of time, conducting sampling, testing the content of NCO, and adding a catalyst and a de-blocking catalyst when a set end-capping rate is reached, thereby obtaining a polyurethane hot-melt foil stamping adhesive after the reaction is ended. The hot-melt foil stamping adhesive provided by the present application has a high bonding firmness on a substrate and a relatively good washing fastness.

Description

Polyurethane hot melt hot stamping adhesive and preparation method thereof Technical Field

[0001] The present application relates to the field of adhesive technology, and in particular to a polyurethane hot melt hot stamping adhesive and a preparation method thereof. Background Art

[0002] Hot stamping adhesive, also known as foil printing adhesive, is a special adhesive with special properties. Hot stamping is the most common process in specialty printing, and it is used to stamp various gold, silver, and laser interference effects on fabrics. It has become particularly popular in recent years. Hot stamping adhesive is typically gravure-printed onto a foil. The foil is then laminated to the fabric, where it is heated and pressurized to adhere. Finally, the foil is removed, leaving the adhesive and the aluminum coating on the foil attached to the fabric, creating a high-gloss finish of gold, silver, or laser interference.

[0003] The adhesives used in hot stamping processes are currently mainly solvent-based polyurethane, non-reactive hot melt adhesive, and water-based adhesive. Solvent-based adhesive is commonly used in hot stamping adhesives on the market. However, the volatile solvent is not friendly to workers and the environment; the bonding strength and water-washing resistance of hot melt adhesive film after lamination are poor; the temperature of hot pressing transfer of non-reactive adhesive powder and particles (polyester, polyamide, vinyl acetate, etc.) is high, the film feels hard after formation, and the fastness decreases significantly after washing; water-based emulsions have the disadvantages of slow drying, long process cycle, and poor water-washing resistance.

[0004] Reactive polyurethane hot melt adhesive is made of polyols and polyisocyanates. Compared with solvent-based polyurethane adhesive and non-reactive hot melt adhesive, it has the advantages of fast positioning, environmental protection and solvent-free, high bonding strength and wide bonding range. However, the existing reactive polyurethane hot melt adhesives on the market still have disadvantages such as poor adhesion to the substrate, low fastness and single applicable objects. Summary of the Invention

[0005] In order to improve the bonding strength and water resistance of hot melt hot stamping adhesive, the present application provides a polyurethane hot melt hot stamping adhesive and a preparation method thereof.

[0006] The polyurethane hot melt hot stamping adhesive provided in this application adopts the following technical solution:

[0007] A polyurethane hot-melt hot stamping adhesive and a preparation method thereof, comprising the following raw materials:

[0008] Polyether polyol 30-45%

[0009] Polyester polyol 20-38%

[0010] Tackifying resin 3-5%

[0011] Diisocyanate 20-30%

[0012] Chain extender 0.5-1%

[0013] Antioxidant 0.1-0.5%

[0014] UV absorber 0.1-0.5%

[0015] Sealant 2-5%

[0016] Catalyst 0.05-0.1%

[0017] Deblocking catalyst 0.05-0.1%.

[0018] By adopting the above technical solution, polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber are mixed, the end-capping rate is adjusted by adding a blocking agent, and the content of -NCO groups is controlled by adding a catalyst and a deblocking catalyst. This allows the hot melt adhesive to form an adhesive layer of a certain strength after being coated on the hot stamping film, and can be deblocked during the subsequent hot pressing transfer process, further solidified with moisture, forming a strong bond with the substrate, and having good water wash resistance.

[0019] Preferably, the polyether polyol is a polyether polyol obtained by ring-opening polymerization of ethylene oxide, ring-opening polymerization of propylene oxide, or ring-opening copolymerization of ethylene oxide and propylene oxide, and has a molecular weight of 1000-3000 Da.

[0020] By adopting the above technical solution, the polyether polyols obtained by ring-opening polymerization of ethylene oxide, ring-opening polymerization of propylene oxide, and ring-opening copolymerization of ethylene oxide and propylene oxide have good water resistance, impact resistance and low-temperature flexibility; further, the preferred polyether polyols are PPG1000, PEG1000, etc.

[0021] Preferably, the polyester polyol is a polyester polyol polymerized from dibasic acids such as adipic acid, sebacic acid, phthalic anhydride, terephthalic acid, isophthalic acid, and ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, etc., and has a molecular weight of 1000-5000 Da.

[0022] By adopting the above technical scheme, polyester polyols synthesized by polymerization of dibasic acids such as adipic acid, sebacic acid, phthalic anhydride, terephthalic acid, isophthalic acid and ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, etc. are divided into liquid polyols, amorphous polyester polyols, and crystalline polyester polyols according to their different forms; further, preferred polyester polyols include liquid polyols synthesized from isophthalic acid, which have good wettability and flexibility, such as Evonik's 7210 and Asahikawa's XCP-2000IPS; preferred crystalline polyester polyols include PBA2000, PBA3500, PHA3000, etc.

[0023] Preferably, the diisocyanate comprises a mixture of one or more of HDI, IPDI, MDI, MDI-50, liquefied MDI, and XDI.

[0024] Preferably, the chain extender is a mixture of one or more of ethylene glycol, butanediol, and hexanediol.

[0025] Preferably, the antioxidant is one of phenolic and aromatic amine antioxidants.

[0026] By adopting the above technical solution, phenolic and aromatic amine antioxidants can effectively inhibit the oxidative degradation reaction of polyurethane materials at high temperatures, play a role in yellowing resistance, and significantly improve the thermal stability of the material; further, the preferred antioxidant is a phenolic antioxidant, including BASF's 1010, 245, 1135, etc.

[0027] Preferably, the blocking agent is a mixture of one or more of 3,5-dimethylpyrazole and methyl ethyl ketone oxime.

[0028] Preferably, the catalyst is bis(2-morpholinediethyl) ether.

[0029] Preferably, the deblocking catalyst is zirconium acetylacetonate.

[0030] The present application provides a method for preparing a polyurethane hot melt hot stamping adhesive, which adopts the following technical solution:

[0031] A method for preparing polyurethane hot melt hot stamping adhesive comprises the following steps:

[0032] Weigh polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber by weight percentage and mix them. After melting at 120-130°C, evacuate the mixture to a vacuum degree of not less than -0.095MPa. When the moisture content is less than 300ppm, cool the mixture to 50-60°C, add the melted diisocyanate, control the temperature at 80-90°C and react for 90-120min. Slowly add the chain extender, continue to maintain the vacuum degree and temperature unchanged and react for 30-40min. Take a sample to test the remaining amount of isocyanate groups, add a blocking agent, continue to react for 1.5-2h, take a sample to test the NCO content, add a catalyst and deblock the catalyst after reaching the set blocking rate, continue stirring for 10-15min and then discharge the material to obtain the polyurethane hot melt hot stamping adhesive.

[0033] By adopting the above technical solution, in the process of preparing polyurethane hot melt hot stamping adhesive, by adjusting the blocking rate, the hot melt adhesive can form an adhesive layer of a certain strength after being coated on the hot stamping film, and can be unblocked during the subsequent hot pressing transfer process, further solidified with moisture, forming a strong bond with the fabric, and the water washing resistance is also significantly improved; by retaining a part of the -NCO group, after being coated on the hot stamping film, the retained part of the -NCO group is first pre-cured to form a film of a certain strength. When transfer is required, the blocked part of the -NCO can be unblocked at a hot pressing temperature of 120-150°C, reacting with moisture, thereby improving the adhesion to the fabric.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. The present invention provides a blocked polyurethane hot melt adhesive with the characteristics of low hot pressing temperature, good bonding strength, and water washability. By adjusting the end-capping ratio, the hot melt adhesive can form an adhesive layer of a certain strength after being coated on the hot stamping film. It can also be unsealed during the subsequent hot pressing transfer process. It further solidifies with moisture to form a strong bond with the fabric and has good water washability.

[0036] 2. The present invention provides a partially blocked reactive polyurethane hot stamping adhesive, which is environmentally friendly and solvent-free. After being coated on the hot stamping film, a portion of the retained -NCO groups are pre-cured to form a film of a certain strength. When transfer is required, the blocked portion of -NCO is unblocked at a hot pressing temperature of 120-150°C, reacting with moisture to improve adhesion to the fabric. DETAILED DESCRIPTION

[0037] The present application is further described in detail below with reference to the embodiments. Example Example 1

[0038] Weigh, by weight, 35% of polyether polyol PPG1000, 13.5% of polyester polyol PBA3500, 18% of Evonik 7210, 5% of tackifying resin TPU resin, 23.9% of diisocyanate MDI, 0.5% of chain extender BDO, 0.2% of antioxidant BASF 1010, 0.3% of UV absorber BASF 292, 3.5% of blocking agent methyl ethyl ketone oxime, 0.05% of catalyst bis(2-morpholinodiethyl) ether, and 0.05% of deblocking catalyst zirconium acetylacetonate.

[0039] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 120℃, evacuate for 2h, make the vacuum degree not less than -0.095MPa, and when the moisture content is less than 300ppm, cool to 50℃, add melted diisocyanate, control the temperature at 80℃ and react for 90min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 30min, take samples to test the residual amount of isocyanate group, add blocking agent, continue to react for 1.5h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 10min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bag. Example 2

[0040] The following ingredients were weighed by weight: 40% polyether polyol PPG1000, 12.5% ​​polyester polyol PHA3000, 13% Asahikawa XCP-2000IPS, 3% tackifying resin acrylic resin, 25.85% diisocyanate MDI, 0.5% chain extender BDO, 0.2% antioxidant BASF 1010, 0.3% UV absorber BASF 292, 4.5% blocking agent 3,5-dimethylpyrazole, 0.05% catalyst bis(2-morpholinodiethyl) ether, and 0.1% deblocking catalyst zirconium acetylacetonate.

[0041] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 120℃, evacuate for 2h, make the vacuum degree not less than -0.095MPa, and when the moisture content is less than 300ppm, cool to 50℃, add melted diisocyanate, control the temperature at 80℃ and react for 90min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 30min, take samples to test the residual amount of isocyanate group, add blocking agent, continue to react for 1.5h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 10min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bag. Example 3

[0042] Weigh by weight 30% of polyether polyol PPG2000, 10% of polyester polyol PHA3000, 28% of Asahikawa XCP-2000IPS, 5% of tackifying resin TPU resin, 23.35% of diisocyanate MDI, 1% of chain extender BDO, 0.2% of antioxidant BASF 1010, 0.3% of UV absorber BASF 292, 2% of blocking agent methyl ethyl ketone oxime, 0.1% of catalyst bis(2-morpholinodiethyl) ether, and 0.05% of deblocking catalyst zirconium acetylacetonate.

[0043] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 120℃, evacuate for 2h, make the vacuum degree not less than -0.095MPa, and when the moisture content is less than 300ppm, cool to 50℃, add melted diisocyanate, control the temperature at 80℃ and react for 90min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 30min, take samples to test the residual amount of isocyanate group, add blocking agent, continue to react for 1.5h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 10min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bag. Example 4

[0044] Weigh, by weight, 40% of polyether polyol PPG1000, 8% of polyester polyol PHA3000, 12% of Asahikawa XCP-2000IPS, 3% of tackifying resin acrylic resin, 30% of diisocyanate MDI, 1% of chain extender BDO, 0.4% of antioxidant BASF 1010, 0.5% of UV absorber BASF 292, 5% of blocking agent 3,5-dimethylpyrazole, 0.05% of catalyst bis(2-morpholinodiethyl) ether, and 0.05% of deblocking catalyst zirconium acetylacetonate.

[0045] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 120℃, evacuate for 2h, make the vacuum degree not less than -0.095MPa, and when the moisture content is less than 300ppm, cool to 50℃, add melted diisocyanate, control the temperature at 80℃ and react for 90min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 30min, take samples to test the residual amount of isocyanate group, add blocking agent, continue to react for 1.5h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 10min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bag. Example 5

[0046] Weigh by weight 40% of polyether polyol PEG1000, 14% of polyester polyol PBA2000, 15% of Evonik 7210, 3% of tackifying resin TPU resin, 23.7% of diisocyanate HDI, 0.5% of chain extender ethylene glycol, 0.1% of antioxidant BASF 1135, 0.1% of UV absorber BASF 1130, 3.5% of blocking agent methyl ethyl ketone oxime, 0.05% of catalyst bis(2-morpholinodiethyl) ether, and 0.05% of deblocking catalyst zirconium acetylacetonate.

[0047] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 120℃, evacuate for 2h, make the vacuum degree not less than -0.095MPa, and when the moisture content is less than 300ppm, cool to 50℃, add melted diisocyanate, control the temperature at 80℃ and react for 90min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 30min, take samples to test the residual amount of isocyanate group, add blocking agent, continue to react for 1.5h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 10min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bag. Example 6

[0048] Weigh, by weight, 35% of polyether polyol PPG1000, 13.5% of polyester polyol PBA3500, 18% of Evonik 7210, 5% of tackifying resin TPU resin, 23.9% of diisocyanate MDI, 0.5% of chain extender BDO, 0.2% of antioxidant BASF 1010, 0.3% of UV absorber BASF 292, 3.5% of blocking agent methyl ethyl ketone oxime, 0.05% of catalyst bis(2-morpholinodiethyl) ether, and 0.05% of deblocking catalyst zirconium acetylacetonate.

[0049] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 125°C, and evacuate for 2.5 hours to make the vacuum degree not less than -0.095MPa. When the moisture content is less than 300ppm, cool to 55°C, add melted diisocyanate, control the temperature at 85°C and react for 105min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 35min, take samples to test the residual amount of isocyanate groups, add blocking agent, continue to react for 1.75h, take samples to test the NCO content, add catalyst and unblock catalyst after reaching the set blocking rate, continue stirring for 12min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bags. Example 7

[0050] Weigh, by weight, 35% of polyether polyol PPG1000, 13.5% of polyester polyol PBA3500, 18% of Evonik 7210, 5% of tackifying resin TPU resin, 23.9% of diisocyanate MDI, 0.5% of chain extender BDO, 0.2% of antioxidant BASF 1010, 0.3% of UV absorber BASF 292, 3.5% of blocking agent methyl ethyl ketone oxime, 0.05% of catalyst bis(2-morpholinodiethyl) ether, and 0.05% of deblocking catalyst zirconium acetylacetonate.

[0051] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 130°C, and evacuate for 3 hours to make the vacuum degree not less than -0.095MPa. When the moisture content is less than 300ppm, cool to 60°C, add melted diisocyanate, control the temperature at 90°C and react for 120min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 40min, take samples to test the residual amount of isocyanate groups, add blocking agent, continue to react for 2h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 15min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bags. Comparative Example Comparative Example 1

[0052] Weigh, by weight percentage, 35% of polyether polyol PPG1000, 15% of polyester polyol PBA3500, 20% of Evonik's 7210, 5% of tackifying resin TPU resin, 23.9% of diisocyanate MDI, 0.5% of chain extender BDO, 0.2% of antioxidant BASF 1010, 0.3% of UV absorber BASF 292, 0% of blocking agent methyl ethyl ketone oxime, 0% of catalyst bis(2-morpholinodiethyl) ether, and 0% of deblocking catalyst zirconium acetylacetonate.

[0053] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 120℃, evacuate for 2h, make the vacuum degree not less than -0.095MPa, and when the moisture content is less than 300ppm, cool to 50-60℃, add melted diisocyanate, control the temperature at 80℃ and react for 90min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 30min, take samples to test the residual amount of isocyanate group, add blocking agent, continue to react for 1.5h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 10min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bag. Comparative Example 2

[0054] Weigh by weight 40% of polyether polyol PPG1000, 8% of polyester polyol PHA3000, 11.2% of Asahikawa XCP-2000IPS, 3% of tackifying resin acrylic resin, 30% of diisocyanate MDI, 1% of chain extender BDO, 0.4% of antioxidant BASF 1010, 0.45% of UV absorber BASF 292, 5.8% of blocking agent methyl ethyl ketone oxime, 0.05% of catalyst bis(2-morpholinodiethyl) ether, and 0.1% of deblocking catalyst zirconium acetylacetonate.

[0055] Mix polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber, melt at 120℃, evacuate for 2h, make the vacuum degree not less than -0.095MPa, and when the moisture content is less than 300ppm, cool to 50-60℃, add melted diisocyanate, control the temperature at 80℃ and react for 90min, slowly add chain extender, continue to keep the vacuum degree and temperature unchanged and react for 30min, take samples to test the residual amount of isocyanate group, add blocking agent, continue to react for 1.5h, take samples to test the NCO content, add catalyst and deblock catalyst after reaching the set blocking rate, continue stirring for 10min and then discharge to obtain polyurethane hot melt hot stamping glue, which is vacuum-packed in aluminum foil bag. Performance testing

[0056] The open time of the polyurethane hot melt hot stamping adhesives obtained in Examples 1-7 and Comparative Examples 1-2 was measured using HG / T 3716-2003 “Determination of open time of hot melt adhesives”. The results are shown in Table 1.

[0057] The softening points of the polyurethane hot melt hot stamping adhesives obtained in Examples 1-7 and Comparative Examples 1-2 before unsealing were tested using GB / T 15332-1992 "Ring and Ball Softening Point Test". The results are shown in Table 1.

[0058] The isocyanate content of the polyurethane hot melt hot stamping adhesives obtained in Examples 1-7 and Comparative Examples 1-2 was tested using HG / T 2409-1992 “Determination of the Isocyanate Content in Polyurethane Prepolymers”. The results are shown in Table 1.

[0059] The washing fastness of the polyurethane hot melt hot stamping adhesives obtained in Examples 1-7 and Comparative Examples 1-2 was tested using HG / T 3697-2016 “Hot Melt Adhesives for Textiles”. The results are shown in Table 1.

[0060] The specific test results are as follows:

[0061] Table 1 Performance test results

[0062] ;

[0063] It can be seen from the test results in Table 1 that the hot melt hot stamping glue prepared by the polyurethane hot melt hot stamping glue formula and preparation method provided in the present application has good water washing color fastness to the substrate, and the softening point of the partially blocked hot melt hot stamping glue is more suitable, and falls in the same range as the unblocking temperature, ensuring that it can be unblocked during transfer, and the final water washing fastness is also good; while the unblocked comparative example 1 has a high softening point before hot stamping, which is not conducive to wetting the fabric to be hot stamped, resulting in poor fastness; the fully blocked comparative example 2 has a low softening point before hot stamping, and the film strength formed on the release paper is low, the transfer is incomplete, and local glue deficiency occurs, and it cannot be used.

[0064] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A polyurethane hot melt hot stamping adhesive, characterized by: Including the following ingredients: Polyether polyol 30-45% Polyester polyol 20-38% Tackifying resin 3-5% Diisocyanate 20-30% Chain extender 0.5-1% Antioxidant 0.1-0.5% UV absorber 0.1-0.5% Sealing agent 2-5% Catalyst 0.05-0.1% Deblocking catalyst 0.05-0.1%.

2. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The polyether polyol is obtained by ring-opening polymerization of ethylene oxide, ring-opening polymerization of propylene oxide, or ring-opening copolymerization of ethylene oxide and propylene oxide, and has a molecular weight of 1000-3000 Da.

3. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The polyester polyol is a polyester polyol prepared by polymerizing dibasic acids such as adipic acid, sebacic acid, phthalic anhydride, terephthalic acid, and isophthalic acid with ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, and neopentyl glycol, and has a molecular weight of 1000-5000 Da.

4. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The diisocyanate includes a mixture of one or more of HDI, IPDI, MDI, MDI-50, liquefied MDI, and XDI.

5. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The chain extender is a mixture of one or more of ethylene glycol, butanediol and hexanediol.

6. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The antioxidant is one of phenolic and aromatic amine antioxidants.

7. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The blocking agent is a mixture of one or more of 3,5-dimethylpyrazole and methyl ethyl ketone oxime.

8. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The catalyst is bis(2-morpholinediethyl) ether.

9. The polyurethane hot melt hot stamping adhesive according to claim 1, characterized in that: The deblocking catalyst is zirconium acetylacetonate.

10. The method for preparing a polyurethane hot melt hot stamping adhesive according to any one of claims 1 to 9, characterized in that: The following steps are involved: Weigh polyether polyol, polyester polyol, tackifying resin, antioxidant and ultraviolet light absorber by weight percentage and mix them. After melting at 120-130°C, evacuate the mixture to a vacuum degree of not less than -0.095MPa. When the moisture content is less than 300ppm, cool the mixture to 50-60°C, add the melted diisocyanate, control the temperature at 80-90°C and react for 90-120min. Slowly add the chain extender, continue to maintain the vacuum degree and temperature unchanged and react for 30-40min. Take a sample to test the remaining amount of isocyanate groups, add a blocking agent, continue to react for 1.5-2h, take a sample to test the NCO content, add a catalyst and deblock the catalyst after reaching the set blocking rate, continue stirring for 10-15min and then discharge the material to obtain the polyurethane hot melt hot stamping adhesive.