A crosslinked moisture-permeable polyurethane transfer film and a method for preparing the same

Abstract

The present application relates to the technical field of layered materials, and particularly relates to a crosslinked moisture-permeable polyurethane transfer film and a preparation method thereof.The crosslinked moisture-permeable polyurethane transfer film comprises a base film layer, a polyurethane transfer layer and an adhesive layer, the polyurethane transfer layer is located on one side of the base film layer, and the adhesive layer is located on the other side of the polyurethane transfer layer; wherein the polyurethane transfer layer is coated on the surface of the base film layer by polyurethane mixed solution and is formed by light curing, and due to the introduction of hydrophilic groups, ultraviolet-resistant components and antioxidant components in the polyurethane emulsion, the polyurethane transfer layer has good moisture-permeable performance and yellowing resistance.

Description

Technical Field

[0001] This invention relates to the field of layered materials technology, and in particular to a cross-linked, moisture-permeable polyurethane transfer membrane and its preparation method. Background Technology

[0002] Transfer film is an intermediate carrier used to hold printed patterns and transfer them onto the printed object. Transfer films are mostly made of polyurethane-based materials, which, due to their good flexibility, durability, and adaptability, can be widely used in various fields.

[0003] Chinese patent CN101204867B discloses a method for manufacturing a PU transfer film. The PU transfer film includes a wet-process polyurethane coating and a dry-process PU transfer coating. The wet-process slurry formulation includes polyurethane resin, DMF, solvent-based pigments, and wood powder, while the dry-process slurry formulation includes polyurethane resin, solvent, pigments, and a leveling agent. However, if the transfer film is used in footwear, clothing, and other apparel applications, good moisture permeability is required. Furthermore, polyurethane-based materials are prone to yellowing, affecting aesthetics. Therefore, it is necessary to improve the moisture permeability and yellowing resistance of polyurethane-based materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a cross-linked, moisture-permeable polyurethane transfer membrane and its preparation method, thereby solving the problem that the moisture permeability and yellowing resistance of polyurethane-based materials in existing technologies need to be improved.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer, wherein the polyurethane transfer layer is located on one side of the base film layer, and the adhesive layer is located on the other side of the polyurethane transfer layer;

[0007] The base film layer includes a PET release film layer;

[0008] The adhesive layer includes a hot melt adhesive film layer;

[0009] The polyurethane transfer layer is formed by coating a polyurethane mixture onto the surface of a base film layer and then photocuring it.

[0010] The polyurethane mixture is prepared by the following steps:

[0011] S1, polycaprolactone diol, polypropylene oxide diol and isophorone diisocyanate were reacted to prepare polyurethane prepolymer; the polyurethane prepolymer was subjected to chain extension reaction of dimethylolbutyric acid, end-capping reaction of pentaerythritol triacrylate, neutralization, shear emulsification to obtain polyurethane emulsion.

[0012] S2,3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid was reacted with glycidyl methacrylate to prepare an alkenyl-modified hindered phenolic antioxidant.

[0013] A polyurethane mixture was prepared by reacting polyurethane emulsion with an alkenyl-modified hindered phenolic antioxidant and an alkenyl-modified nano-titanium dioxide.

[0014] Preferably, in step S1, the preparation of the polyurethane emulsion specifically includes:

[0015] Polycaprolactone diol was heated to a first set temperature, and isophorone diisocyanate and dibutyltin dilaurate were added. After the reaction was completed, a polyurethane prepolymer was obtained. Dimethylolbutyric acid was added to the polyurethane prepolymer, and the reaction was continued. After the reaction was completed, the temperature was lowered to a second set temperature, and pentaerythritol triacrylate was added. The reaction was carried out again. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. After neutralization with alkali, deionized water was added, and shear emulsification was performed to obtain a polyurethane emulsion.

[0016] Preferably, the molar ratio of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate is (0.4-0.6):(0.4-0.6):(1.5-2.5), the amount of dibutyltin dilaurate added is 0.5%-0.8% of the total mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate, the amount of dimethylolbutyric acid added is 8%-10% of the total mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate, the amount of pentaerythritol triacrylate added is 3%-5% of the mass of isophorone diisocyanate, and the amount of deionized water added is 2.5-3.5 times the mass of the reaction product.

[0017] The reaction conditions are as follows: under nitrogen protection, the reaction is carried out at the first set temperature for 2-3 hours; the reaction is continued under nitrogen protection at the first set temperature for 2-3 hours; and the reaction is repeated under nitrogen protection at the second set temperature for 3-4 hours.

[0018] The first set temperature is 80-90℃, and the second set temperature is 65-75℃.

[0019] Preferably, in step S2, the preparation of the alkenyl-modified hindered phenolic antioxidant specifically includes:

[0020] Dissolve 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid in ethanol to obtain a 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid solution.

[0021] Glycidyl methacrylate, triphenylphosphine, and hydroquinone were added to a solution of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid. After the reaction was completed, the precipitate was filtered and dried to obtain an alkenyl-modified hindered phenolic antioxidant.

[0022] Preferably, the molar ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to glycidyl methacrylate is 1:(1.05-1.2). When preparing the 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid solution, the mass ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to ethanol is 1:(15-25). The amount of triphenylphosphine added is 0.5%-1.5% of the total mass of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidyl methacrylate. The amount of hydroquinone added is 0.5%-1% of the total mass of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidyl methacrylate. The reaction conditions are reflux reaction at 75-85°C for 1-3 hours.

[0023] Preferably, in step S2, the preparation of the polyurethane mixture specifically includes:

[0024] Alkenyl-modified nano-titanium dioxide and alkenyl-modified hindered phenolic antioxidant were added to a polyurethane emulsion. The mixture was heated to the third set temperature, and an aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate was added. After stirring and pre-emulsifying, an aqueous solution of potassium persulfate was added dropwise. After the addition was complete, the mixture was allowed to react, and the temperature was raised to the fourth set temperature to continue the reaction. After the reaction was complete, the mixture was cooled to room temperature, and the photoinitiator 1-hydroxycyclohexylphenyl ketone was added. The mixture was stirred to obtain a polyurethane mixture.

[0025] Preferably, the mass ratio of polyurethane emulsion, alkenyl modified nano-titanium dioxide, alkenyl modified hindered phenolic antioxidant, sodium salt aqueous solution of 2-acrylamido-2-methylpropanesulfonate, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:(2-4):(2-4):(16-20):(10-15):(0.5-1.5), and the reaction conditions are to react at a third set temperature for 2-3 hours, and to continue the reaction at a fourth set temperature for 1-2 hours.

[0026] The third temperature setting is 70-80℃, and the fourth temperature setting is 90-95℃.

[0027] Preferably, the alkenyl-modified nano-titanium dioxide in S2 is prepared by the following steps:

[0028] The pH of the ethanol aqueous solution was adjusted to 3.5-4.5, γ-(methacryloyloxy)propyltrimethoxysilane (silane coupling agent KH570) was added, and after stirring and hydrolysis, nano-titanium dioxide was added. After the reaction was completed, the mixture was filtered, washed, and dried to obtain alkenyl-modified nano-titanium dioxide.

[0029] The mass ratio of nano-titanium dioxide, aqueous ethanol solution, and γ-(methacryloyloxy)propyltrimethoxysilane is 8:(80-120):(6-10), and the reaction conditions are reflux reaction at 75-85℃ for 2.5-3.5h.

[0030] Preferably, the aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate is a 5wt%-10wt% aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate; and the aqueous solution of potassium persulfate is a 5wt% aqueous solution of potassium persulfate.

[0031] This invention also discloses a method for preparing the cross-linked, moisture-permeable polyurethane transfer membrane as described above, comprising the following steps:

[0032] Step (1): Coat one side of the PET release film with the polyurethane mixture. After coating, light cure to form a polyurethane transfer layer on the PET release film.

[0033] Step (2): A hot melt adhesive film is bonded to the surface of the polyurethane transfer layer. After pressing and cooling, an adhesive layer is formed on the polyurethane transfer layer to obtain a cross-linked, moisture-permeable polyurethane transfer film.

[0034] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0035] Preferably, in step (1), the coating amount of the polyurethane mixture is 180-240 g / m³. 2 The conditions for photocuring are to irradiate with ultraviolet light at a wavelength of 365nm for 30-40 seconds.

[0036] Preferably, in step (2), the thickness of the hot melt adhesive film is 0.1-0.2 mm, the softening point of the hot melt adhesive film is 120-130℃, and the pressing pressure is 4-6 MPa.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The polyurethane transfer membrane of the present invention combines the properties of polyether polyurethane and polyester polyurethane, possessing both the wear resistance and flexibility of polyether polyurethane and the high mechanical strength of polyester polyurethane, resulting in excellent overall performance of the polyurethane transfer membrane.

[0039] In this invention, during the preparation of the polyurethane emulsion, polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate are first reacted to obtain an isocyanate-terminated polyurethane prepolymer. Dimethylolbutyric acid is used as a chain extender, and the introduced carboxyl groups are hydrophilic groups. Through the adsorption-diffusion-desorption of these hydrophilic groups, the directional expulsion of water vapor is promoted, improving the moisture permeability of the polyurethane. Pentaerythritol triacrylate is used for end-capping. Pentaerythritol triacrylate is a multifunctional monomer, and the introduced acrylate can not only react with alkenyl-modified hindered phenolic antioxidants and alkenyl-modified nano-titanium dioxide as initiators... The polymerization reaction occurs, linking hindered phenolic antioxidants and nano-titanium dioxide to polyurethane resin molecules through stable chemical bonds. This improves the dispersion uniformity and compatibility of hindered phenolic antioxidants and nano-titanium dioxide in polyurethane, thereby enhancing the yellowing resistance of the polyurethane transfer film. Simultaneously, it provides cross-linking curing points for polyurethane, enabling it to cross-link and cure under ultraviolet light irradiation and the action of a photoinitiator. After photocuring, a highly cross-linked three-dimensional network structure is formed, which can improve the heat resistance of the polyurethane transfer film and prevent the influence of heating and melting the hot melt adhesive film on the polyurethane transfer layer when bonding the hot melt adhesive film to form an adhesive layer.

[0040] The alkenyl-modified hindered phenolic antioxidant in this invention is prepared by the bonding reaction of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidyl methacrylate. It can not only introduce acrylate groups that participate in the polymerization reaction, but also improve the moisture permeability of polyurethane transfer membranes by the ring-opening reaction between the carboxyl group on the 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid molecule and the epoxy group on the glycidyl methacrylate molecule. Attached Figure Description

[0041] Figure 1 This is a schematic diagram illustrating the preparation of an alkenyl-modified hindered phenolic antioxidant by reacting 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with glycidyl methacrylate in this invention.

[0042] Figure 2 The graph shows the moisture permeability test results of the polyurethane transfer layer samples prepared in Examples 3-7 and Comparative Examples 1-2 of the present invention.

[0043] Figure 3 The graph shows the results of the anti-yellowing performance test of the polyurethane transfer layer samples prepared in Examples 3-7 and Comparative Examples 1-2 of the present invention. Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment discloses a method for preparing alkenyl-modified nano-titanium dioxide, including the following steps:

[0047] The pH of a 95wt% ethanol aqueous solution was adjusted to 4 using 1mol / L hydrochloric acid. γ-(methacryloyloxy)propyltrimethoxysilane was added, and the mixture was hydrolyzed at 300 rpm for 30 min at room temperature. Then, nano-titanium dioxide was added. The mass ratio of nano-titanium dioxide, 95wt% ethanol aqueous solution, and γ-(methacryloyloxy)propyltrimethoxysilane was 8:100:8. The mixture was refluxed at 80℃ for 3 h. After the reaction was completed, the mixture was filtered, washed three times with ethanol, and dried in a vacuum drying oven at 50℃ to constant weight to obtain alkenyl-modified nano-titanium dioxide.

[0048] Example 2

[0049] This embodiment discloses a method for preparing an alkenyl-modified hindered phenolic antioxidant, comprising the following steps:

[0050] Dissolve 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid in ethanol at a mass ratio of 1:20 to obtain a 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid solution.

[0051] Glycidyl methacrylate, triphenylphosphine, and hydroquinone were added to a solution of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid. The mixture was refluxed at 80°C for 2 hours. After the reaction was completed, five times the mass of ethanol and deionized water were added to precipitate the product. The precipitate was filtered and dried in a vacuum drying oven at 50°C to constant weight to obtain an alkenyl-modified hindered phenolic antioxidant.

[0052] The molar ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to glycidyl methacrylate is 1:1.1, the amount of triphenylphosphine added is 1% of the total mass of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidyl methacrylate, and the amount of hydroquinone added is 0.8% of the total mass of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidyl methacrylate.

[0053] Example 3

[0054] This embodiment discloses a method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane, comprising the following steps:

[0055] Step 1: Prepare the polyurethane mixture, including:

[0056] S1. Polycaprolactone diol and polypropylene glycol were heated to 80°C, and isophorone diisocyanate and dibutyltin dilaurate were added. The molar ratio of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate was 0.4:0.4:1.5, and the amount of dibutyltin dilaurate added was 0.5% of the total mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate. The reaction was carried out under nitrogen protection at 80°C for 3 hours. After the reaction was completed, a polyurethane prepolymer was obtained. Dimethylolbutyric acid was added to the polyurethane prepolymer. The amount of dimethylolbutyric acid added was equal to the mass of polycaprolactone diol and polypropylene glycol. The mixture was prepared by reacting 8% of isophorone diisocyanate by mass at 80°C under nitrogen protection for 3 hours. After the reaction was completed, the temperature was lowered to 65°C, and pentaerythritol triacrylate was added at 3% of the mass of isophorone diisocyanate. The mixture was then reacted at 65°C under nitrogen protection for 4 hours. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. Triethylamine was added to the reaction product to adjust the pH to 7. Deionized water was added at 2.5 times the mass of the reaction product. The mixture was sheared and emulsified at a linear velocity of 40 m / s for 40 minutes to obtain a polyurethane emulsion.

[0057] S2. The alkenyl-modified nano-titanium dioxide prepared in Example 1 and the alkenyl-modified hindered phenolic antioxidant prepared in Example 2 were added to the polyurethane emulsion. The temperature was raised to 70°C, and 5 wt% sodium 2-acrylamido-2-methylpropanesulfonate solution was added. After pre-emulsification at a stirring speed of 1500 r / min for 30 min, 5 wt% potassium persulfate solution was added dropwise over a period of 30 min. After the addition was completed, the reaction was carried out at 70°C for 3 h, and then the temperature was raised to 90°C. The reaction was continued at 90°C for 2 h. After the reaction was completed, the temperature was cooled to room temperature, and 1-hydroxycyclohexyl phenyl ketone photoinitiator was added. The mixture was stirred at a stirring speed of 1200 r / min for 60 min to obtain a polyurethane mixture.

[0058] The mass ratio of polyurethane emulsion, alkenyl-modified nano-titanium dioxide, alkenyl-modified hindered phenolic antioxidant, sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:2:2:16:10:0.5.

[0059] Step 2: Apply the polyurethane mixture to one side of the PET release film at a coating amount of 180 g / m². 2After coating, the film is irradiated with ultraviolet light at a wavelength of 365nm for 30s for photocuring to form a polyurethane transfer layer on the PET release film.

[0060] Step 3: Lay a hot melt adhesive film onto the surface of the polyurethane transfer layer, press and cool to form an adhesive layer on the polyurethane transfer layer, and obtain a cross-linked moisture-permeable polyurethane transfer film.

[0061] The thickness of the hot melt adhesive film is 0.15 mm, the softening point of the hot melt adhesive film is 126℃, and the pressing pressure is 5 MPa.

[0062] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0063] Example 4

[0064] This embodiment discloses a method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane, comprising the following steps:

[0065] Step 1: Prepare the polyurethane mixture, including:

[0066] S1. Polycaprolactone diol and polypropylene glycol were heated to 90°C, and isophorone diisocyanate and dibutyltin dilaurate were added. The molar ratio of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate was 0.6:0.6:2.5. The amount of dibutyltin dilaurate added was 0.8% of the total mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate. The reaction was carried out under nitrogen protection at 90°C for 2 hours. After the reaction was completed, a polyurethane prepolymer was obtained. Dimethylolbutyric acid was added to the polyurethane prepolymer. The amount of dimethylolbutyric acid added was equal to the mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate. 10% of the mass of isophorone diisocyanate was added and reacted at 90°C for 2 hours under nitrogen protection. After the reaction was completed, the temperature was lowered to 75°C, and pentaerythritol triacrylate was added at 5% of the mass of isophorone diisocyanate. The reaction was carried out at 75°C for 3 hours under nitrogen protection. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. Triethylamine was added to the reaction product to make the pH value of the reaction product 7. Deionized water was added at 3.5 times the mass of the reaction product. The mixture was sheared and emulsified at a linear velocity of 60 m / s for 20 minutes to obtain a polyurethane emulsion.

[0067] S2. The alkenyl-modified nano-titanium dioxide prepared in Example 1 and the alkenyl-modified hindered phenolic antioxidant prepared in Example 2 were added to the polyurethane emulsion. The temperature was raised to 80°C, and 10wt% sodium 2-acrylamido-2-methylpropanesulfonate solution was added. After pre-emulsification by stirring at 1500r / min for 30min, 5wt% potassium persulfate solution was added dropwise over 60min. After the addition was completed, the reaction was carried out at 80°C for 2h, then the temperature was raised to 95°C and the reaction was continued at 95°C for 1h. After the reaction was completed, the mixture was cooled to room temperature, and 1-hydroxycyclohexyl phenyl ketone photoinitiator was added. The mixture was stirred at 1200r / min for 60min to obtain the polyurethane mixture.

[0068] The mass ratio of polyurethane emulsion, alkenyl-modified nano-titanium dioxide, alkenyl-modified hindered phenolic antioxidant, sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:4:4:20:15:1.5.

[0069] Step 2: Apply the polyurethane mixture to one side of the PET release film at a coating amount of 240 g / m². 2 After coating, the film is irradiated with ultraviolet light at a wavelength of 365nm for 40s for photocuring to form a polyurethane transfer layer on the PET release film.

[0070] Step 3: Lay a hot melt adhesive film onto the surface of the polyurethane transfer layer, press and cool to form an adhesive layer on the polyurethane transfer layer, and obtain a cross-linked moisture-permeable polyurethane transfer film.

[0071] The thickness of the hot melt adhesive film is 0.15 mm, the softening point of the hot melt adhesive film is 126℃, and the pressing pressure is 5 MPa.

[0072] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0073] Example 5

[0074] This embodiment discloses a method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane, comprising the following steps:

[0075] Step 1: Prepare the polyurethane mixture, including:

[0076] S1. Polycaprolactone diol and polypropylene glycol diol are heated to 85°C, and isophorone diisocyanate and dibutyltin dilaurate are added. The molar ratio of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate is 0.45:0.45:1.8. The amount of dibutyltin dilaurate added is 0.6% of the total mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. The reaction is carried out under nitrogen protection at 85°C for 2.5 hours. After the reaction is completed, a polyurethane prepolymer is obtained. Dimethylolbutyric acid is added to the polyurethane prepolymer. The amount of dimethylolbutyric acid added is equal to the total mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. The isophorone diisocyanate was added at 8.5% of its mass and reacted at 85°C for 2.5 h under nitrogen protection. After the reaction was completed, the temperature was lowered to 70°C, and pentaerythritol triacrylate was added at 3.5% of the mass of isophorone diisocyanate. The reaction was carried out again at 70°C under nitrogen protection for 3.5 h. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. Triethylamine was added to the reaction product to make the pH value of the reaction product 7, and deionized water was added at 3 times the mass of the reaction product. The mixture was sheared and emulsified at a linear velocity of 50 m / s for 30 min to obtain a polyurethane emulsion.

[0077] S2. The alkenyl-modified nano-titanium dioxide prepared in Example 1 and the alkenyl-modified hindered phenolic antioxidant prepared in Example 2 were added to the polyurethane emulsion. The temperature was raised to 75°C, and 7.5wt% sodium 2-acrylamido-2-methylpropanesulfonate solution was added. After pre-emulsification by stirring at 1500r / min for 30min, 5wt% potassium persulfate solution was added dropwise over a period of 45min. After the addition was completed, the mixture was reacted at 75°C for 2.5h, then the temperature was raised to 92°C and the reaction was continued at 92°C for 1.5h. After the reaction was completed, the mixture was cooled to room temperature, and 1-hydroxycyclohexyl phenyl ketone photoinitiator was added. The mixture was stirred at 1200r / min for 60min to obtain the polyurethane mixture.

[0078] The mass ratio of polyurethane emulsion, alkenyl-modified nano-titanium dioxide, alkenyl-modified hindered phenolic antioxidant, sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:2.5:2.5:17:11:0.8.

[0079] Step 2: Apply the polyurethane mixture to one side of the PET release film at a coating amount of 210 g / m². 2 After coating, the film is irradiated with ultraviolet light at a wavelength of 365nm for 35s for photocuring to form a polyurethane transfer layer on the PET release film.

[0080] Step 3: Lay a hot melt adhesive film onto the surface of the polyurethane transfer layer, press and cool to form an adhesive layer on the polyurethane transfer layer, and obtain a cross-linked moisture-permeable polyurethane transfer film.

[0081] The thickness of the hot melt adhesive film is 0.15 mm, the softening point of the hot melt adhesive film is 126℃, and the pressing pressure is 5 MPa.

[0082] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0083] Example 6

[0084] This embodiment discloses a method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane, comprising the following steps:

[0085] Step 1: Prepare the polyurethane mixture, including:

[0086] S1. Polycaprolactone diol and polypropylene glycol diol are heated to 85°C, and isophorone diisocyanate and dibutyltin dilaurate are added. The molar ratio of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate is 0.5:0.5:2. The amount of dibutyltin dilaurate added is 0.65% of the total mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. The reaction is carried out under nitrogen protection at 85°C for 2.5 hours. After the reaction is completed, a polyurethane prepolymer is obtained. Dimethylolbutyric acid is added to the polyurethane prepolymer. The amount of dimethylolbutyric acid added is equal to the total mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. 9% of isophorone diisocyanate by mass was added and reacted at 85°C for 2.5 h under nitrogen protection. After the reaction was completed, the temperature was lowered to 70°C, and pentaerythritol triacrylate was added at 4% of the mass of isophorone diisocyanate. The reaction was carried out again at 70°C for 3.5 h under nitrogen protection. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. Triethylamine was added to the reaction product to make the pH value of the reaction product 7. Deionized water was added at 3 times the mass of the reaction product. The mixture was sheared and emulsified at a linear velocity of 50 m / s for 30 min to obtain a polyurethane emulsion.

[0087] S2. The alkenyl-modified nano-titanium dioxide prepared in Example 1 and the alkenyl-modified hindered phenolic antioxidant prepared in Example 2 were added to the polyurethane emulsion. The temperature was raised to 75°C, and 7.5wt% sodium 2-acrylamido-2-methylpropanesulfonate solution was added. After pre-emulsification by stirring at 1500r / min for 30min, 5wt% potassium persulfate solution was added dropwise over a period of 45min. After the addition was completed, the mixture was reacted at 75°C for 2.5h, then the temperature was raised to 92°C and the reaction was continued at 92°C for 1.5h. After the reaction was completed, the mixture was cooled to room temperature, and 1-hydroxycyclohexyl phenyl ketone photoinitiator was added. The mixture was stirred at 1200r / min for 60min to obtain the polyurethane mixture.

[0088] The mass ratio of polyurethane emulsion, alkenyl-modified nano-titanium dioxide, alkenyl-modified hindered phenolic antioxidant, sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:3:3:18:12.5:1.

[0089] Step 2: Apply the polyurethane mixture to one side of the PET release film at a coating amount of 210 g / m². 2 After coating, the film is irradiated with ultraviolet light at a wavelength of 365nm for 35s for photocuring to form a polyurethane transfer layer on the PET release film.

[0090] Step 3: Lay a hot melt adhesive film onto the surface of the polyurethane transfer layer, press and cool to form an adhesive layer on the polyurethane transfer layer, and obtain a cross-linked moisture-permeable polyurethane transfer film.

[0091] The thickness of the hot melt adhesive film is 0.15 mm, the softening point of the hot melt adhesive film is 126℃, and the pressing pressure is 5 MPa.

[0092] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0093] Example 7

[0094] This embodiment discloses a method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane, comprising the following steps:

[0095] Step 1: Prepare the polyurethane mixture, including:

[0096] S1. Polycaprolactone diol and polypropylene glycol diol are heated to 85°C, and isophorone diisocyanate and dibutyltin dilaurate are added. The molar ratio of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate is 0.55:0.55:2.3. The amount of dibutyltin dilaurate added is 0.7% of the total mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. The reaction is carried out under nitrogen protection at 85°C for 2.5 hours. After the reaction is completed, a polyurethane prepolymer is obtained. Dimethylolbutyric acid is added to the polyurethane prepolymer. The amount of dimethylolbutyric acid added is equal to the total mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. 9.5% of isophorone diisocyanate by mass was added and reacted at 85°C for 2.5 h under nitrogen protection. After the reaction was completed, the temperature was lowered to 70°C, and pentaerythritol triacrylate was added at a rate of 4.5% of the mass of isophorone diisocyanate. The reaction was carried out again at 70°C under nitrogen protection for 3.5 h. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. Triethylamine was added to the reaction product to adjust the pH to 7, and deionized water was added at a rate of 3 times the mass of the reaction product. The mixture was sheared and emulsified at a linear velocity of 50 m / s for 30 min to obtain a polyurethane emulsion.

[0097] S2. The alkenyl-modified nano-titanium dioxide prepared in Example 1 and the alkenyl-modified hindered phenolic antioxidant prepared in Example 2 were added to the polyurethane emulsion. The temperature was raised to 75°C, and 7.5wt% sodium 2-acrylamido-2-methylpropanesulfonate solution was added. After pre-emulsification by stirring at 1500r / min for 30min, 5wt% potassium persulfate solution was added dropwise over a period of 45min. After the addition was completed, the mixture was reacted at 75°C for 2.5h, then the temperature was raised to 92°C and the reaction was continued at 92°C for 1.5h. After the reaction was completed, the mixture was cooled to room temperature, and 1-hydroxycyclohexyl phenyl ketone photoinitiator was added. The mixture was stirred at 1200r / min for 60min to obtain the polyurethane mixture.

[0098] The mass ratio of polyurethane emulsion, alkenyl-modified nano-titanium dioxide, alkenyl-modified hindered phenolic antioxidant, sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:3.5:3.5:19:14:1.3.

[0099] Step 2: Apply the polyurethane mixture to one side of the PET release film at a coating amount of 210 g / m². 2 After coating, the film is irradiated with ultraviolet light at a wavelength of 365nm for 35s for photocuring to form a polyurethane transfer layer on the PET release film.

[0100] Step 3: Lay a hot melt adhesive film onto the surface of the polyurethane transfer layer, press and cool to form an adhesive layer on the polyurethane transfer layer, and obtain a cross-linked moisture-permeable polyurethane transfer film.

[0101] The thickness of the hot melt adhesive film is 0.15 mm, the softening point of the hot melt adhesive film is 126℃, and the pressing pressure is 5 MPa.

[0102] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0103] Comparative Example 1

[0104] This comparative example discloses a method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane, comprising the following steps:

[0105] Step 1: Prepare the polyurethane mixture, including:

[0106] S1. Polycaprolactone diol and polypropylene glycol diol are heated to 80°C, and isophorone diisocyanate and dibutyltin dilaurate are added. The molar ratio of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate is 0.4:0.4:1.5. The amount of dibutyltin dilaurate added is 0.5% of the total mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. The reaction is carried out under nitrogen protection at 80°C for 3 hours. After the reaction is completed, a polyurethane prepolymer is obtained. 1,4-Butanediol is added to the polyurethane prepolymer. The amount of 1,4-butanediol added is equal to the mass of polycaprolactone diol, polypropylene glycol diol, and isophorone diisocyanate. The reaction mixture, consisting of 8% of the total mass of alcohol and isophorone diisocyanate, was continued at 80°C for 3 hours under nitrogen protection. After the reaction was completed, the temperature was lowered to 65°C, and pentaerythritol triacrylate was added at 3% of the mass of isophorone diisocyanate. The mixture was then reacted at 65°C for 4 hours under nitrogen protection. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. Triethylamine was added to the reaction product to adjust the pH to 7, and deionized water was added at 2.5 times the mass of the reaction product. The mixture was sheared and emulsified at a linear velocity of 40 m / s for 40 minutes to obtain a polyurethane emulsion.

[0107] S2. The alkenyl-modified nano-titanium dioxide prepared in Example 1 and the alkenyl-modified hindered phenolic antioxidant prepared in Example 2 were added to the polyurethane emulsion. The temperature was raised to 70°C, and 5 wt% sodium 2-acrylamido-2-methylpropanesulfonate solution was added. After pre-emulsification at a stirring speed of 1500 r / min for 30 min, 5 wt% potassium persulfate solution was added dropwise over a period of 30 min. After the addition was completed, the reaction was carried out at 70°C for 3 h, and then the temperature was raised to 90°C. The reaction was continued at 90°C for 2 h. After the reaction was completed, the temperature was cooled to room temperature, and 1-hydroxycyclohexyl phenyl ketone photoinitiator was added. The mixture was stirred at a stirring speed of 1200 r / min for 60 min to obtain a polyurethane mixture.

[0108] The mass ratio of polyurethane emulsion, alkenyl-modified nano-titanium dioxide, alkenyl-modified hindered phenolic antioxidant, sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:2:2:16:10:0.5.

[0109] Step 2: Apply the polyurethane mixture to one side of the PET release film at a coating amount of 180 g / m². 2 After coating, the film is irradiated with ultraviolet light at a wavelength of 365nm for 30s for photocuring to form a polyurethane transfer layer on the PET release film.

[0110] Step 3: Lay a hot melt adhesive film onto the surface of the polyurethane transfer layer, press and cool to form an adhesive layer on the polyurethane transfer layer, and obtain a cross-linked moisture-permeable polyurethane transfer film.

[0111] The thickness of the hot melt adhesive film is 0.15 mm, the softening point of the hot melt adhesive film is 126℃, and the pressing pressure is 5 MPa.

[0112] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0113] Comparative Example 2

[0114] This comparative example discloses a method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane, comprising the following steps:

[0115] Step 1: Prepare the polyurethane mixture, including:

[0116] S1. Polycaprolactone diol and polypropylene glycol were heated to 80°C, and isophorone diisocyanate and dibutyltin dilaurate were added. The molar ratio of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate was 0.4:0.4:1.5, and the amount of dibutyltin dilaurate added was 0.5% of the total mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate. The reaction was carried out under nitrogen protection at 80°C for 3 hours. After the reaction was completed, a polyurethane prepolymer was obtained. Dimethylolbutyric acid was added to the polyurethane prepolymer. The amount of dimethylolbutyric acid added was equal to the mass of polycaprolactone diol and polypropylene glycol. The mixture was prepared by reacting 8% of isophorone diisocyanate by mass at 80°C under nitrogen protection for 3 hours. After the reaction was completed, the temperature was lowered to 65°C, and pentaerythritol triacrylate was added at 3% of the mass of isophorone diisocyanate. The mixture was then reacted at 65°C under nitrogen protection for 4 hours. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. Triethylamine was added to the reaction product to adjust the pH to 7. Deionized water was added at 2.5 times the mass of the reaction product. The mixture was sheared and emulsified at a linear velocity of 40 m / s for 40 minutes to obtain a polyurethane emulsion.

[0117] S2. Add nano-titanium dioxide to the polyurethane emulsion, and add 5wt% sodium 2-acrylamido-2-methylpropanesulfonate solution. After pre-emulsification at a stirring speed of 1500r / min for 30min, add the photoinitiator 1-hydroxycyclohexyl phenyl ketone and continue stirring at a stirring speed of 1200r / min for 60min to obtain a polyurethane mixture.

[0118] The mass ratio of polyurethane emulsion, alkenyl-modified nano-titanium dioxide, sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:2:16:0.5.

[0119] Step 2: Apply the polyurethane mixture to one side of the PET release film at a coating amount of 180 g / m². 2 After coating, the film is irradiated with ultraviolet light at a wavelength of 365nm for 30s for photocuring to form a polyurethane transfer layer on the PET release film.

[0120] Step 3: Lay a hot melt adhesive film onto the surface of the polyurethane transfer layer, press and cool to form an adhesive layer on the polyurethane transfer layer, and obtain a cross-linked moisture-permeable polyurethane transfer film.

[0121] The thickness of the hot melt adhesive film is 0.15 mm, the softening point of the hot melt adhesive film is 126℃, and the pressing pressure is 5 MPa.

[0122] The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

[0123] In the above examples and comparative examples, the particle size of nano-titanium dioxide is 50 nm; polycaprolactone diol is PCL-1000 with a molecular weight of 1000; and polypropylene glycol is PPG-1000 with a molecular weight of 1000.

[0124] Test case

[0125] The polyurethane transfer layers prepared in Examples 3-7 and Comparative Examples 1-2 were peeled off from the PET release film to obtain polyurethane transfer layer samples. Performance tests were then performed on the polyurethane transfer layer samples.

[0126] (1) Moisture permeability: The moisture permeability flux of the polyurethane transfer layer sample was measured, and the results are shown in Table 1.

[0127] Table 1

[0128]

[0129] As shown in Table 1, the polyurethane transfer layer in the polyurethane transfer membrane prepared by this invention exhibits good moisture permeability. In the preparation of the polyurethane emulsion, dimethylolbutyric acid (DMPO) is used as a chain extender, and the introduced carboxyl groups are hydrophilic groups. Through the adsorption-diffusion-desorption of these hydrophilic groups, the directional expulsion of water vapor is promoted, improving the moisture permeability of the polyurethane. Furthermore, the alkenyl-modified hindered phenolic antioxidant in this invention is prepared by reacting 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with glycidyl methacrylate. The hydroxyl groups generated during the reaction also improve the moisture permeability of the polyurethane transfer membrane. Compared to Example 3, in Comparative Example 1, 1,4-butanediol was used as a chain extender, and the hydrophilic effect of the carboxyl groups was absent, resulting in a significant decrease in moisture permeability. In Comparative Example 2, no alkenyl-modified hindered phenolic antioxidant was added, and the moisture permeability also decreased.

[0130] (2) Anti-yellowing performance: The color change value, i.e., color difference (ΔE), of the polyurethane transfer layer sample before and after photo-oxidation (irradiation under 380nm ultraviolet light for 1000h) and thermo-oxidative aging (thermo-oxidative aging at 140℃ for 1000h) was measured respectively. The measurement results are shown in Table 2:

[0131] Table 2

[0132]

[0133] As shown in Table 2, the polyurethane transfer film prepared by this invention exhibits good anti-yellowing properties. The introduction of hindered phenolic antioxidant and nano-titanium dioxide effectively improves the polyurethane's resistance to photo-oxidation and thermo-oxidative aging, thereby resulting in good anti-yellowing properties. Compared with Example 3, in Comparative Example 2, without the addition of alkenyl-modified hindered phenolic antioxidant, the resistance to thermo-oxidative aging was significantly reduced, and the nano-titanium dioxide, without alkenyl modification, also showed a decrease in photo-oxidation resistance.

[0134] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A cross-linked, moisture-permeable polyurethane transfer membrane, characterized in that, It includes a base film layer, a polyurethane transfer layer and an adhesive layer, wherein the polyurethane transfer layer is located on one side of the base film layer and the adhesive layer is located on the other side of the polyurethane transfer layer; The base film layer includes a PET release film layer; The adhesive layer includes a hot melt adhesive film layer; The polyurethane transfer layer is formed by coating a polyurethane mixture onto the surface of a base film layer and then photocuring it. The polyurethane mixture is prepared by the following steps: S1, polycaprolactone diol, polypropylene oxide diol and isophorone diisocyanate were reacted to prepare polyurethane prepolymer; the polyurethane prepolymer was subjected to chain extension reaction of dimethylolbutyric acid, end-capping reaction of pentaerythritol triacrylate, neutralization, shear emulsification to obtain polyurethane emulsion. S2,3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid was reacted with glycidyl methacrylate to prepare an alkenyl-modified hindered phenolic antioxidant. A polyurethane mixture was prepared by reacting polyurethane emulsion with an alkenyl-modified hindered phenolic antioxidant and an alkenyl-modified nano-titanium dioxide.

2. The cross-linked, moisture-permeable polyurethane transfer membrane according to claim 1, characterized in that, In step S1, the preparation of the polyurethane emulsion specifically includes: Polycaprolactone diol and polypropylene glycol were heated to a first set temperature, and isophorone diisocyanate and dibutyltin dilaurate were added. After the reaction was completed, a polyurethane prepolymer was obtained. Dimethylolbutyric acid was added to the polyurethane prepolymer, and the reaction was continued. After the reaction was completed, the temperature was lowered to a second set temperature, and pentaerythritol triacrylate was added. The reaction was carried out again. After the reaction was completed, the temperature was lowered to room temperature to obtain the reaction product. After neutralization with alkali, deionized water was added, and shear emulsification was performed to obtain a polyurethane emulsion.

3. The cross-linked, moisture-permeable polyurethane transfer membrane according to claim 2, characterized in that, The molar ratio of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate is (0.4-0.6):(0.4-0.6):(1.5-2.5). The amount of dibutyltin dilaurate added is 0.5%-0.8% of the total mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate. The amount of dimethylolbutyric acid added is 8%-10% of the total mass of polycaprolactone diol, polypropylene glycol, and isophorone diisocyanate. The amount of pentaerythritol triacrylate added is 3%-5% of the mass of isophorone diisocyanate. The amount of deionized water added is 2.5-3.5 times the mass of the reaction product. The reaction conditions are as follows: under nitrogen protection, the reaction is carried out at the first set temperature for 2-3 hours; the reaction is continued under nitrogen protection at the first set temperature for 2-3 hours; and the reaction is repeated under nitrogen protection at the second set temperature for 3-4 hours. The first set temperature is 80-90℃, and the second set temperature is 65-75℃.

4. The cross-linked, moisture-permeable polyurethane transfer membrane according to claim 1, characterized in that, In step S2, the preparation of an alkenyl-modified hindered phenolic antioxidant specifically includes: Dissolve 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid in ethanol to obtain a 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid solution. Glycidyl methacrylate, triphenylphosphine, and hydroquinone were added to a solution of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid. After the reaction was completed, the precipitate was filtered and dried to obtain an alkenyl-modified hindered phenolic antioxidant.

5. The cross-linked, moisture-permeable polyurethane transfer membrane according to claim 4, characterized in that, The molar ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to glycidyl methacrylate is 1:(1.05-1.2). When preparing a 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid solution, the mass ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid to ethanol is 1:(15-25). The amount of triphenylphosphine added is 0.5%-1.5% of the total mass of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidyl methacrylate. The amount of hydroquinone added is 0.5%-1% of the total mass of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and glycidyl methacrylate. The reaction conditions are reflux reaction at 75-85℃ for 1-3 hours.

6. The cross-linked, moisture-permeable polyurethane transfer membrane according to claim 1, characterized in that, In step S2, the preparation of the polyurethane mixture specifically includes: Alkenyl-modified nano-titanium dioxide and alkenyl-modified hindered phenolic antioxidant were added to a polyurethane emulsion. The mixture was heated to the third set temperature, and an aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate was added. After stirring and pre-emulsifying, an aqueous solution of potassium persulfate was added dropwise. After the addition was complete, the mixture was allowed to react, and the temperature was raised to the fourth set temperature to continue the reaction. After the reaction was complete, the mixture was cooled to room temperature, and the photoinitiator 1-hydroxycyclohexylphenyl ketone was added. The mixture was stirred to obtain a polyurethane mixture.

7. The cross-linked, moisture-permeable polyurethane transfer membrane according to claim 2, characterized in that, The mass ratio of polyurethane emulsion, alkenyl modified nano-titanium dioxide, alkenyl modified hindered phenolic antioxidant, sodium salt aqueous solution of 2-acrylamido-2-methylpropanesulfonate, potassium persulfate aqueous solution, and 1-hydroxycyclohexyl benzophenone is 100:(2-4):(2-4):(16-20):(10-15):(0.5-1.5). The reaction conditions are: reacting at the third set temperature for 2-3 hours, and continuing the reaction at the fourth set temperature for 1-2 hours. The third temperature setting is 70-80℃, and the fourth temperature setting is 90-95℃.

8. A method for preparing a cross-linked, moisture-permeable polyurethane transfer membrane as described in any one of claims 1-7, characterized in that, Includes the following steps: Step (1): Coat one side of the PET release film with the polyurethane mixture. After coating, light cure to form a polyurethane transfer layer on the PET release film. Step (2): A hot melt adhesive film is bonded to the surface of the polyurethane transfer layer. After pressing and cooling, an adhesive layer is formed on the polyurethane transfer layer to obtain a cross-linked, moisture-permeable polyurethane transfer film. The cross-linked, moisture-permeable polyurethane transfer membrane includes a base film layer, a polyurethane transfer layer, and an adhesive layer. The base film layer is a PET release film layer, and the adhesive layer is a hot melt adhesive film layer.

9. The method for preparing the cross-linked, moisture-permeable polyurethane transfer membrane according to claim 8, characterized in that, In step (1), the coating amount of the polyurethane mixture is 180-240 g / m². 2 The conditions for photocuring are to irradiate with ultraviolet light at a wavelength of 365nm for 30-40 seconds.

10. The method for preparing the cross-linked, moisture-permeable polyurethane transfer membrane according to claim 8, characterized in that, In step (2), the thickness of the hot melt adhesive film is 0.1-0.2 mm, the softening point of the hot melt adhesive film is 120-130℃, and the pressing pressure is 4-6 MPa.

Images