Low-temperature-resistant polyurethane transfer film and preparation method thereof

Abstract

The invention relates to the technical field of layered materials, and discloses a low-temperature-resistant polyurethane transfer film and a preparation method thereof. The multi-layer structure heat transfer film with a glue layer and a polyurethane-based transfer layer is prepared, and a photo-curing transfer layer material containing polyurethane acrylate containing polyether, polybutadiene blocks and organic silicon branched chains with good low-temperature resistance and sulfhydrylation graphene oxide with excellent far infrared performance is prepared; the low temperature resistance and the water resistance of the heat transfer film are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of layered materials, in particular to a low-temperature-resistant polyurethane transfer film and a preparation method thereof. BACKGROUND

[0002] The heat transfer film refers to a special functional printing film that the graphics with adhesive are separated from the base film together with the protective layer under the action of heat and pressure, and firmly bonded to the surface of the printing material. The heat transfer film generally includes a base layer, a release layer, a protective layer, an ink layer and a bonding layer. After the graphics are transferred to the printing material, the protective layer becomes the outermost layer on the surface of the printing material because the release layer does not follow the transfer. The protective layer needs to have good mechanical properties. The traditional protective layer is a thermally cured coating, such as a polyurethane-based coating. However, the space density of the formed coating is insufficient, and the chemical bond of the node is single, so the mechanical strength is limited, which cannot meet the increasingly high requirements for product performance.

[0003] The temperature range for long-term use of polyurethane is from -40℃ to 80℃. For some extremely cold regions, the use of polyurethane is very limited, and the problem of embrittlement occurs, losing the elasticity of the material itself. Therefore, maintaining the elasticity of polyurethane at low temperature is the primary task of research. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a low-temperature-resistant polyurethane transfer film and a preparation method thereof. The transfer film is a multi-layer structure heat transfer film with a glue layer and a polyurethane-based transfer layer, and has excellent low-temperature resistance and water resistance.

[0005] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows: A preparation method of a low-temperature-resistant polyurethane transfer film, comprising the following steps: Step (1), uniformly mix polyurethane acrylate, mercapto-oxidized graphene, tripropylene glycol diacrylate, trimethylolpropane triacrylate and photoinitiator in a light-proof environment to obtain a transfer layer material; Coat the transfer layer material on one side of the base film with a release layer, and then perform photocuring after coating to obtain a transfer layer / base film composite film; Step (2), press the glue layer and the side of the transfer layer / base film composite film with the transfer layer together, and then cool to obtain a low-temperature-resistant polyurethane transfer film.

[0006] Preferably, in step (1), the mass ratio of polyurethane acrylate, mercapto-oxidized graphene, tripropylene glycol diacrylate, trimethylolpropane triacrylate and photoinitiator is 60:5-8:15-20:15-20:4-5.

[0007] Preferably, in the step (1), the base film is a PET release film; the curing condition is: photocuring for 30-40s under ultraviolet light with wavelength of 365nm; the thickness of the transfer layer is 4-6μm.

[0008] Preferably, in the step (1), the polyurethane acrylate is prepared by the following steps: S1, mixing hexafluorobutyl acrylate and N,N-dimethylformamide, warming, dropping the mixed solution of mercaptoethanol and triethylamine, after dropping, reacting, after the reaction, washing, and reducing pressure distillation to obtain the hydroxyl fluorine-containing monomer; Mixing HDI trimer and catalyst dibutyltin dilaurate, adding the hydroxyl fluorine-containing monomer, and reacting to obtain the fluorine-containing isocyanate after the reaction. S2, mixing hydroxyl-terminated polybutadiene, KH590, tetrahydrofuran, and benzoin dimethyl ether, and reacting to obtain the silane-modified hydroxyl-terminated polybutadiene after the reaction and rotary evaporation. Mixing the silane-modified hydroxyl-terminated polybutadiene, monohydroxyl silicone oil, tetrahydrofuran, and dibutyltin dilaurate, and reacting to obtain the silicone-modified hydroxyl-terminated polybutadiene after the reaction and rotary evaporation. Mixing the fluorine-containing isocyanate, polytetrahydrofuran ether diol, silicone-modified hydroxyl-terminated polybutadiene, and dibutyltin dilaurate, and reacting to obtain the polyurethane acrylate after the reaction, cooling, adding p-hydroxyanisole and hydroxyethyl acrylate, and continuing to react.

[0009] Preferably, in the step (1), in the preparation of the polyurethane acrylate, in S1, the molar ratio of hexafluorobutyl acrylate, mercaptoethanol, and HDI trimer is 1:1.5-2:1; in the mixed solution of mercaptoethanol and triethylamine, the mass ratio of mercaptoethanol to triethylamine is 200:1.

[0010] Preferably, in the step (1), in the preparation of the polyurethane acrylate, in S1, in the preparation of the hydroxyl fluorine-containing monomer, the dropping condition of the mixed solution of mercaptoethanol and triethylamine is dropping for 20-30min at 50℃, and the reaction condition is reacting for 8-10h at 50℃.

[0011] Preferably, in the step (1), in the preparation of the polyurethane acrylate, in S1, in the preparation of the fluorine-containing isocyanate, the mass ratio of HDI trimer to catalyst dibutyltin dilaurate is 10:0.01, and the reaction condition is reacting for 1.5-2h at 70-80℃.

[0012] Preferably, in the step (1), the polyurethane acrylate is prepared by the following steps:

[0013] Preferably, in the step (1), the polyurethane acrylate is prepared by the following steps:

[0014] Preferably, in the step (1), the polyurethane acrylate is prepared by the following steps:

[0015] Preferably, in the step (1), the thiolated graphene oxide is prepared by the following steps: The graphene oxide and water are mixed and ultrasonically dispersed for 20-30 min, and then heated to 50-60℃, and then 1.8wt% sulfuric acid aqueous solution and mercaptoacetic acid are sequentially added, and then reacted at 50-60℃ for 5h, and then cooled, and then filtered, and then washed to neutral, and then dried to obtain the thiolated graphene oxide; The graphene oxide, water, 1.8wt% sulfuric acid aqueous solution, and mercaptoacetic acid are mixed in a solid-liquid ratio of 0.2g:150-200mL:100-120mL:5-6mL.

[0016] Preferably, in the step (2), the adhesive layer is a hot melt adhesive film with a thickness of 0.15-0.3mm, and the pressing condition is that the temperature is 120-130℃ and the pressure is 5-6MPa.

[0017] Preferably, the low-temperature-resistant polyurethane transfer film is prepared by the above-mentioned method.

[0018] Compared with the prior art, the low-temperature-resistant polyurethane transfer film has the following advantages: The application prepares a multilayer structure heat transfer film with a glue layer and a polyurethane-based transfer layer, and effectively improves the low-temperature resistance and water resistance of the heat transfer film by preparing a photocuring transfer layer material containing polyether, polybutadiene block and organosilicon branched polyurethane acrylate with good low-temperature resistance, and far-infrared performance excellent mercapto graphene oxide.

[0019] In the application, the hydroxyl fluorine-containing monomer is prepared by click reaction of hexafluorobutyl acrylate and mercaptoethanol, and the fluorine-containing isocyanate is prepared by reaction of the hydroxyl group with the isocyanate group of HDI trimer, and the polyurethane acrylate containing polyether chain segment, polybutadiene block and organosilicon branched chain is obtained by copolymerization of the fluorine-containing isocyanate, polytetrahydrofuran ether diol and organosilicon modified hydroxyl-terminated polybutadiene, and termination with hydroxyethyl acrylate. The fluorine-containing isocyanate has a hydrophobic group, which can improve the water resistance of the polyurethane acrylate; the polytetrahydrofuran ether diol and the organosilicon modified hydroxyl-terminated polybutadiene both have low glass transition temperature, good flexibility and excellent low-temperature resistance, which can effectively improve the low-temperature resistance of the polyurethane acrylate; the organosilicon modified hydroxyl-terminated polybutadiene is formed by click chemistry reaction of hydroxyl-terminated polybutadiene and the mercapto group of KH590 and then polymerization with monohydroxy silicone oil, the hydrophobic organosilicon chain segment is introduced therein, which cooperates with the polybutadiene chain segment to improve the water resistance of the polyurethane acrylate, and the organosilicon chain segment also has excellent low-temperature resistance, which positively adds to the improvement of the low-temperature resistance of the polyurethane acrylate. In the application, the polyurethane acrylate, mercapto graphene oxide and diluent and photoinitiator are mixed to form a transfer layer material, after photocuring, the components are connected by chemical bonds through reaction, the crosslinking degree of the material is improved, and the water resistance is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the low-temperature resistant polyurethane transfer film prepared in the application; Figure 2 is a columnar chart of the tensile strength change rate of the test samples 1-5 in the performance test; Figure 3 is a columnar chart of the water contact angle of the samples 1-5 in the performance test; In the drawings: 1, glue layer; 2, transfer layer; 3, base film. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0022] Embodiment 1

[0023] The present embodiment discloses a preparation method of a transfer layer material, comprising the following steps: Step (1), mixing hexafluorobutyl acrylate and N,N-dimethylformamide at a mass ratio of 1:1, and then adding a mixed solution of mercaptoethanol and triethylamine dropwise at 50℃, the dropwise adding time is 30 min, after the dropwise adding is completed, reacting at 50℃ for 8 h, after the reaction is completed, washing with water to remove mercaptoethanol and N,N-dimethylformamide, and then distilling under reduced pressure at 50℃ to obtain a hydroxyl fluorine-containing monomer; Mixing HDI trimer and a catalyst dibutyltin dilaurate at a mass ratio of 10:0.01, and then adding the hydroxyl fluorine-containing monomer, and reacting at 70℃ for 2 h, to obtain a fluorine-containing isocyanate after the reaction is completed; The molar ratio of hexafluorobutyl acrylate, mercaptoethanol and HDI trimer is 1:1.5:1; the mass ratio of mercaptoethanol and triethylamine in the mixed solution is 200:1; Step (2), mixing the fluorine-containing isocyanate, polytetrahydrofuran ether diol, silicone-modified hydroxyl-terminated polybutadiene and the catalyst dibutyltin dilaurate, and then reacting at 60℃ for 4 h, after the reaction is completed, cooling to 50℃, adding a polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate, and then continuing to react for 1 h to obtain a polyurethane acrylate; The mass ratio of the fluorine-containing isocyanate, polytetrahydrofuran ether diol, silicone-modified hydroxyl-terminated polybutadiene, catalyst dibutyltin dilaurate, polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate is 7:10:15:0.018:0.03:1.5; The silicone-modified hydroxyl-terminated polybutadiene is prepared by the following steps: Mixing hydroxyl-terminated polybutadiene, KH590, tetrahydrofuran and a photoinitiator benzoin dimethyl ether at a solid-liquid ratio of 10 g:2 g:300 mL:0.05 g, and then reacting under the condition of ultraviolet light irradiation at a wavelength of 365 nm and a power of 150 W for 4 h, after the reaction is completed, removing the solvent by rotary evaporation to obtain the silane-modified hydroxyl-terminated polybutadiene; Mixing silane-modified hydroxyl-terminated polybutadiene, monohydroxy silicone oil, tetrahydrofuran, and dibutyltin dilaurate at a solid-liquid ratio of 10 g:0.5 g:100 mL:0.5 mL, and reacting at 40°C for 24 h; after the reaction is completed, the solvent is removed by rotary evaporation to obtain silicone-modified hydroxyl-terminated polybutadiene; Step (3), mixing polyurethane acrylate, mercapto graphene oxide, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and photoinitiator Irgacure 184 at a mass ratio of 60:5:15:20:4 in a light-proof environment to obtain a transfer layer material; The mercapto graphene oxide is prepared by the following steps: Mixing graphene oxide and water, ultrasonic dispersion for 20 min, heating to 60°C, and sequentially adding 1.8 wt% sulfuric acid aqueous solution and mercaptoacetic acid, and reacting at 60°C for 5 h; after the reaction is completed, cooling to room temperature, suction filtration, washing with water until neutral, and drying at 50°C for 24 h to obtain mercapto graphene oxide; The solid-liquid ratio of graphene oxide, water, 1.8 wt% sulfuric acid aqueous solution, and mercaptoacetic acid is 0.2 g:150 mL:100 mL:5 mL.

[0024] Example 2

[0025] The present embodiment discloses a preparation method of a transfer layer material, comprising the following steps: Step (1), mixing hexafluorobutyl acrylate and N,N-dimethylformamide at a mass ratio of 1:1, heating to 50°C, and dropwise adding a mixed solution of mercaptoethanol and triethylamine, the dropwise adding time being 30 min; after the dropwise adding is completed, reacting at 50°C for 9 h; after the reaction is completed, washing with water to remove mercaptoethanol and N,N-dimethylformamide, and distilling under reduced pressure at 50°C to obtain a hydroxyl-containing fluoromonomer; Mixing HDI trimer and catalyst dibutyltin dilaurate at a mass ratio of 10:0.01, and adding the hydroxyl-containing fluoromonomer, and reacting at 75°C for 1.8 h; after the reaction is completed, a fluorine-containing isocyanate is obtained; The molar ratio of hexafluorobutyl acrylate, mercaptoethanol, and HDI trimer is 1:1.8:1; in the mixed solution of mercaptoethanol and triethylamine, the mass ratio of mercaptoethanol to triethylamine is 200:1; Step (2), mixing the fluorine-containing isocyanate, polytetrahydrofuran ether diol, silicone-modified hydroxyl-terminated polybutadiene, and catalyst dibutyltin dilaurate, and reacting at 65°C for 3.5 h; after the reaction is completed, cooling to 50°C, adding polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate, and continuing to react for 1.5 h to obtain polyurethane acrylate; The mass ratio of the fluorine-containing isocyanate, polytetrahydrofuran ether diol, silicone-modified hydroxyl-terminated polybutadiene, catalyst dibutyltin dilaurate, polymerization inhibitor p-hydroxyanisole, and hydroxyethyl acrylate is 7.3:10:15:0.018:0.03:1.8; The silicone-modified hydroxyl-terminated polybutadiene is prepared by the following steps: The hydroxyl-terminated polybutadiene, KH590, tetrahydrofuran, and benzoin dimethyl ether are mixed at a solid-liquid ratio of 10 g:2.3 g:300 mL:0.05 g, and then reacted under the condition of ultraviolet light irradiation at a wavelength of 365 nm and a power of 150 W for 4 h. After the reaction is completed, the solvent is removed by rotary evaporation to obtain the silicone-modified hydroxyl-terminated polybutadiene. The silicone-modified hydroxyl-terminated polybutadiene, monohydroxy silicone oil, tetrahydrofuran, and dibutyltin dilaurate are mixed at a solid-liquid ratio of 10 g:0.8 g:100 mL:0.5 mL, and then reacted at a temperature of 40℃ for 24 h. After the reaction is completed, the solvent is removed by rotary evaporation to obtain the silicone-modified hydroxyl-terminated polybutadiene. Step (3), the polyurethane acrylate, thiolated graphene oxide, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and photoinitiator Irgacure 184 are uniformly mixed in a mass ratio of 60:6.5:15:20:4.5 in a light-proof environment to obtain the transfer layer material. The thiolated graphene oxide is prepared by the following steps: The graphene oxide and water are mixed and ultrasonically dispersed for 20 min, and then heated to 60℃. 1.8wt% sulfuric acid aqueous solution and mercaptoacetic acid are sequentially added, and then reacted at a temperature of 60℃ for 5 h. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed with water until neutral, and then dried at a temperature of 50℃ for 24 h to obtain the thiolated graphene oxide. The solid-liquid ratio of the graphene oxide, water, 1.8wt% sulfuric acid aqueous solution, and mercaptoacetic acid is 0.2 g:150 mL:100 mL:5 mL.

[0026] Example 3

[0027] The present embodiment discloses a preparation method of a transfer layer material, which comprises the following steps: Step (1), the hexafluorobutyl acrylate and N,N-dimethylformamide are mixed in a mass ratio of 1:1, heated to 50℃, and then a mixed solution of mercaptoethanol and triethylamine is added dropwise. The dropwise addition is performed for 30 min, and then reacted at a temperature of 50℃ for 10 h after the dropwise addition is completed. After the reaction is completed, water is added to remove the mercaptoethanol and N,N-dimethylformamide, and then distilled under reduced pressure at a temperature of 50℃ to obtain the hydroxyl-containing fluorine monomer. The HDI trimer, the catalyst dibutyltin dilaurate are mixed in a mass ratio of 10:0.01, the hydroxyl fluorine-containing monomer is added, and the reaction is carried out at 80 DEG C for 1.5 h; after the reaction is completed, the fluorine-containing isocyanate is obtained; The molar ratio of hexafluorobutyl acrylate, mercaptoethanol and HDI trimer is 1:2:1; the mass ratio of mercaptoethanol and triethylamine in the mixed solution is 200:1; Step (2), the fluorine-containing isocyanate, polytetrahydrofuran ether glycol, silicone modified hydroxyl terminated polybutadiene, catalyst dibutyltin dilaurate are mixed, and the reaction is carried out at 70 DEG C for 3 h; after the reaction is completed, the temperature is lowered to 50 DEG C, the polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate are added, and the reaction is continued for 2 h to obtain the polyurethane acrylate; The mass ratio of fluorine-containing isocyanate, polytetrahydrofuran ether glycol, silicone modified hydroxyl terminated polybutadiene, catalyst dibutyltin dilaurate, polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate is 7.5:10:15:0.018:0.03:2. The silicone modified hydroxyl terminated polybutadiene is prepared by the following steps: The hydroxyl terminated polybutadiene, KH590, tetrahydrofuran and benzoin dimethyl ether are mixed in a solid-liquid ratio of 10g:2.5g:300mL:0.05g, and the reaction is carried out under the condition of ultraviolet light irradiation at a wavelength of 365nm and a power of 150W for 4h; after the reaction is completed, the solvent is removed by rotary evaporation to obtain the silane modified hydroxyl terminated polybutadiene; The silane modified hydroxyl terminated polybutadiene, monohydroxy silicone oil, tetrahydrofuran and dibutyltin dilaurate are mixed in a solid-liquid ratio of 10g:1g:100mL:0.5mL, and the reaction is carried out at 40 DEG C for 24 h; after the reaction is completed, the solvent is removed by rotary evaporation to obtain the silicone modified hydroxyl terminated polybutadiene; Step (3), the polyurethane acrylate, mercaptized graphene oxide, tripropylene glycol diacrylate, trimethylolpropane triacrylate and photoinitiator Irgacure 184 are mixed in a mass ratio of 60:8:15:20:5 in a light-proof environment to obtain the transfer layer material; The mercaptized graphene oxide is prepared by the following steps: The graphene oxide and water are mixed and ultrasonically dispersed for 20 min, and then 1.8wt% sulfuric acid aqueous solution and mercaptoacetic acid are added in sequence; the reaction is carried out at 60 DEG C for 5 h; after the reaction is completed, the temperature is cooled to room temperature, and then the mixture is suction filtered and washed with water until neutral; the mixture is dried at 50 DEG C for 24 h to obtain the mercaptized graphene oxide; The solid-liquid ratio of graphene oxide, water, 1.8wt% sulfuric acid aqueous solution and mercaptoacetic acid is 0.2g:150mL:100mL:5mL.

[0028] Example 4

[0029] The present example discloses a method for preparing a low-temperature-resistant polyurethane transfer film, comprising the following steps: Step (1), PET release film is used as the base film, and the transfer layer material prepared in Example 1 is coated on the side of the base film with the release layer. After coating, it is cured in ultraviolet light with a wavelength of 365 nm for 30 s to form a transfer layer with a thickness of 4 μm, obtaining a transfer layer / base film composite film; Step (2), a hot melt adhesive film with a thickness of 0.15 mm is used as the adhesive layer, and is laminated with the side of the transfer layer / base film composite film with the transfer layer under the condition of a temperature of 120 ℃ and a pressure of 5 MPa, and is cooled to obtain a low-temperature-resistant polyurethane transfer film.

[0030] Example 5

[0031] The present example discloses a method for preparing a low-temperature-resistant polyurethane transfer film, comprising the following steps: Step (1), PET release film is used as the base film, and the transfer layer material prepared in Example 2 is coated on the side of the base film with the release layer. After coating, it is cured in ultraviolet light with a wavelength of 365 nm for 30 s to form a transfer layer with a thickness of 4 μm, obtaining a transfer layer / base film composite film; Step (2), a hot melt adhesive film with a thickness of 0.15 mm is used as the adhesive layer, and is laminated with the side of the transfer layer / base film composite film with the transfer layer under the condition of a temperature of 120 ℃ and a pressure of 5 MPa, and is cooled to obtain a low-temperature-resistant polyurethane transfer film.

[0032] Example 6

[0033] The present example discloses a method for preparing a low-temperature-resistant polyurethane transfer film, comprising the following steps: Step (1), PET release film is used as the base film, and the transfer layer material prepared in Example 3 is coated on the side of the base film with the release layer. After coating, it is cured in ultraviolet light with a wavelength of 365 nm for 30 s to form a transfer layer with a thickness of 4 μm, obtaining a transfer layer / base film composite film; Step (2), a hot melt adhesive film with a thickness of 0.15 mm is used as the adhesive layer, and is laminated with the side of the transfer layer / base film composite film with the transfer layer under the condition of a temperature of 120 ℃ and a pressure of 5 MPa, and is cooled to obtain a low-temperature-resistant polyurethane transfer film.

[0034] Comparative Example 1 The present comparative example discloses a method for preparing a transfer layer material, comprising the following steps: Step (1), mix hexafluorobutyl acrylate and N,N-dimethylformamide in a mass ratio of 1:1, heat to 50℃, drop the mixed solution of mercaptoethanol and triethylamine, the drop time is 30 min, after the drop is completed, react at 50℃ for 8h, after the reaction is completed, wash with water to remove mercaptoethanol and N,N-dimethylformamide, and distill under reduced pressure at 50℃ to obtain a hydroxyl-containing fluorine monomer; Mix HDI trimer and catalyst dibutyltin dilaurate in a mass ratio of 10:0.01, add the hydroxyl-containing fluorine monomer, and react at 70℃ for 2h, to obtain a fluorine-containing isocyanate after the reaction is completed; The molar ratio of hexafluorobutyl acrylate, mercaptoethanol and HDI trimer is 1:1.5:1; the mass ratio of mercaptoethanol and triethylamine in the mixed solution is 200:1; Step (2), mix the fluorine-containing isocyanate, polytetrahydrofuran ether diol, hydroxyl-terminated polybutadiene and catalyst dibutyltin dilaurate, react at 60℃ for 4h, after the reaction is completed, cool to 50℃, add the polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate, and continue to react for 1h to obtain a polyurethane acrylate; The mass ratio of fluorine-containing isocyanate, polytetrahydrofuran ether diol, hydroxyl-terminated polybutadiene, catalyst dibutyltin dilaurate, polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate is 7:10:15:0.018:0.03:1.5; Step (3), mix the polyurethane acrylate, mercapto-oxidized graphene, tripropylene glycol diacrylate, trimethylolpropane triacrylate and photoinitiator Irgacure 184 in a mass ratio of 60:5:15:20:4 in a light-proof environment to obtain a transfer layer material; The mercapto-oxidized graphene is prepared by the following steps: Mix graphene oxide and water, ultrasonically disperse for 20 min, heat to 60℃, and then add 1.8wt% sulfuric acid solution and mercaptoacetic acid in sequence, react at 60℃ for 5h, after the reaction is completed, cool to room temperature, filter, wash with water until neutral, and dry at 50℃ for 24h to obtain mercapto-oxidized graphene; The solid-liquid ratio of graphene oxide, water, 1.8wt% sulfuric acid solution and mercaptoacetic acid is 0.2g:150mL:100mL:5mL.

[0035] Comparative Example 2 This comparative example discloses a preparation method of a transfer layer material, comprising the following steps: Step (1), mixing HDI trimer, polytetrahydrofuran ether diol, silicone modified hydroxyl terminated polybutadiene, catalyst dibutyltin dilaurate at 60℃ for 4h, after the reaction is completed, cooling to 50℃, adding polymerization inhibitor p-hydroxyanisole and hydroxyethyl acrylate, continuing to react for 1h to obtain polyurethane acrylate; The mass ratio of HDI trimer, polytetrahydrofuran ether diol, silicone modified hydroxyl terminated polybutadiene, catalyst dibutyltin dilaurate, polymerization inhibitor p-hydroxyanisole, and hydroxyethyl acrylate is 7:10:15:0.018:0.03:1.5. The silicone modified hydroxyl terminated polybutadiene is prepared by the following steps: Mixing hydroxyl terminated polybutadiene, KH590, tetrahydrofuran, and benzoin dimethyl ether at a solid-liquid ratio of 10g:2g:300mL:0.05g, and reacting under the condition of ultraviolet light with a wavelength of 365nm and a power of 150W for 4h, then removing the solvent by rotary evaporation to obtain silane modified hydroxyl terminated polybutadiene. Mixing silane modified hydroxyl terminated polybutadiene, monohydroxy silicone oil, tetrahydrofuran, and dibutyltin dilaurate at a solid-liquid ratio of 10g:0.5g:100mL:0.5mL, and reacting at 40℃ for 24h, then removing the solvent by rotary evaporation to obtain silicone modified hydroxyl terminated polybutadiene. Step (3), mixing polyurethane acrylate, sulfhydrylated graphene oxide, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and photoinitiator Irgacure 184 at a mass ratio of 60:5:15:20:4 in a light-proof environment to obtain a transfer layer material. The sulfhydrylated graphene oxide is prepared by the following steps: Mixing graphene oxide and water, ultrasonic dispersion for 20min, heating to 60℃, sequentially adding 1.8wt% sulfuric acid aqueous solution and mercaptoacetic acid, reacting at 60℃ for 5h, after the reaction is completed, cooling to room temperature, suction filtration, washing with water until neutral, drying at 50℃ for 24h to obtain sulfhydrylated graphene oxide. The solid-liquid ratio of graphene oxide, water, 1.8wt% sulfuric acid aqueous solution, and mercaptoacetic acid is 0.2g:150mL:100mL:5mL.

[0036] Comparative Example 3 This comparative example discloses a preparation method of a polyurethane transfer film, comprising the following steps: Step (1), PET release film was used as the base film, and the transfer layer material prepared in Comparative Example 1 was coated on the side of the base film having a release layer. After coating, it was cured in ultraviolet light with a wavelength of 365 nm for 30 s to form a transfer layer with a thickness of 4 μm, thereby obtaining a transfer layer / base film composite film. Step (2), a hot melt adhesive film with a thickness of 0.15 mm was used as the adhesive layer, and was laminated with the side of the transfer layer / base film composite film having the transfer layer under the conditions of a temperature of 120 °C and a pressure of 5 MPa, and was cooled to obtain a polyurethane transfer film.

[0037] Comparative Example 4 The present comparative example discloses a preparation method of a polyurethane transfer film, comprising the following steps: Step (1), PET release film was used as the base film, and the transfer layer material prepared in Comparative Example 2 was coated on the side of the base film having a release layer. After coating, it was cured in ultraviolet light with a wavelength of 365 nm for 30 s to form a transfer layer with a thickness of 4 μm, thereby obtaining a transfer layer / base film composite film. Step (2), a hot melt adhesive film with a thickness of 0.15 mm was used as the adhesive layer, and was laminated with the side of the transfer layer / base film composite film having the transfer layer under the conditions of a temperature of 120 °C and a pressure of 5 MPa, and was cooled to obtain a polyurethane transfer film.

[0038] In the above examples and comparative examples, the polytetrahydrofuran ether diol was polytetrahydrofuran ether diol 1000; the hydroxyl value of the hydroxyl-terminated polybutadiene was 0.47-0.53 mmol / g; the Mn of the monohydroxy silicone oil was 1000; the graphene oxide and the hot melt adhesive film were all commercially available, and the softening point of the hot melt adhesive film was 120-130 °C.

[0039] Test Example The transfer layer materials prepared in Examples 1-3 and Comparative Examples 1-2 were coated on a release film, and the coating thickness was 1 mm. After curing in ultraviolet light with a wavelength of 365 nm for 30 s, the release film was removed to obtain samples 1-5, and mechanical properties and low temperature resistance were tested. The specific test results are shown in Table 1: Table 1

[0040] The detection of each index in Table 1 was carried out according to the following standards: the tensile strength was determined according to GB / T 528-2009 “Determination of Tensile Stress-Strain Properties of Vulcanized or Thermoplastic Rubber”; the low temperature resistance was represented by the change rate of tensile strength. The sample 1-5 was placed in a temperature of -20 °C for a low temperature resistance test, and the test time was 12 h. After taking out, the tensile test was carried out, and the change rate of tensile strength was calculated.

[0041] The transfer film prepared in Examples 4-6 and Comparative Examples 3-4 was attached to the surface of the leather base cloth, and the adhesive layer of the transfer film was contacted with the leather base cloth, and then the sample was pressed and cooled at 130°C, and was recorded as Sample 1-5. The hydrophobic performance of the side of Sample 1-5 with the transfer film was tested by measuring the static water contact angle. The specific test results are shown in Table 2: Table 2

[0042] According to the test results in Tables 1 and 2, it can be seen that the hot transfer film prepared in the present application has good mechanical properties, excellent low-temperature resistance and water resistance. This is because the present application prepares a light-cured transfer layer material containing polyurethane acrylate with good low-temperature resistance, polybutadiene block and organosilicon branched chain, and mixes it with components such as thiolated graphene oxide with excellent far-infrared performance. After light curing, the components are connected by chemical bonds through reaction, which improves the crosslinking degree of the material and further improves the water resistance. Among them, the fluorine-containing isocyanate has a hydrophobic group, which can improve the water resistance of the polyurethane acrylate; polytetrahydrofuran ether diol and organosilicon modified hydroxyl terminated polybutadiene both have low glass transition temperature and good flexibility, and excellent low-temperature resistance, which can effectively improve the low-temperature resistance of the polyurethane acrylate; the organosilicon modified hydroxyl terminated polybutadiene is formed by the click chemistry reaction of hydroxyl terminated polybutadiene and the thiol group of KH590 and then polymerization with monohydroxy silicone oil, which introduces hydrophobic organosilicon segments into it, cooperates with the polybutadiene segment to improve the water resistance of the polyurethane acrylate, and the organosilicon segment also has excellent low-temperature resistance, which positively adds to the improvement of the low-temperature resistance of the polyurethane acrylate.

[0043] In Comparative Example 1, the hydroxyl terminated polybutadiene is not modified, and lacks the improvement of the low-temperature resistance and water resistance by the organosilicon segment, so the low-temperature resistance and hydrophobic performance of Sample 4 and Sample 5 are not as good as those of the examples. In Comparative Example 2, the HDI trimer is not modified, and lacks the improvement of the hydrophobic performance of the material by the fluorine-containing segment, so the hydrophobic performance of Sample 5 and Sample 5 is not as good as that of the examples.

[0044] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a low temperature resistant polyurethane transfer film, characterized by, The method comprises the following steps: Step (1), uniformly mix polyurethane acrylate, mercapto graphene oxide, tripropylene glycol diacrylate, trimethylolpropane triacrylate and photoinitiator in a light-proof environment to obtain a transfer layer material; Coat the transfer layer material on one side of the base film with a release layer, and after coating is completed, photocure to obtain a transfer layer / base film composite film; Step (2), press the adhesive layer and the side of the transfer layer / base film composite film with the transfer layer together, and cool to obtain a low-temperature-resistant polyurethane transfer film.

2. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 1, characterized in that, In step (1), the mass ratio of polyurethane acrylate, mercapto graphene oxide, tripropylene glycol diacrylate, trimethylolpropane triacrylate and photoinitiator is 60:5-8:15-20:15-20:4-5; the base film is a PET release film; the curing condition is photocuring for 30-40s under ultraviolet light with a wavelength of 365nm; and the thickness of the transfer layer is 4-6μm.

3. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 1, characterized in that, In step (1), the polyurethane acrylate is prepared by the following steps: S1, mix hexafluorobutyl acrylate and N,N-dimethylformamide, warm, and drop the mixed solution of mercaptoethanol and triethylamine, after drop is completed, react, after reaction is completed, wash, and reduce pressure distillation to obtain a hydroxyl fluorine-containing monomer; Mix HDI trimer and catalyst dibutyltin dilaurate, add the hydroxyl fluorine-containing monomer, react, and after reaction is completed, obtain a fluorine-containing isocyanate; S2, mix hydroxyl-terminated polybutadiene, KH590, tetrahydrofuran and benzoin dimethyl ether, react, after reaction is completed, rotary evaporation to obtain silane-modified hydroxyl-terminated polybutadiene; Mix the silane-modified hydroxyl-terminated polybutadiene, monohydroxy silicone oil, tetrahydrofuran and dibutyltin dilaurate, react, after reaction is completed, rotary evaporation to obtain silicone-modified hydroxyl-terminated polybutadiene; Mix the fluorine-containing isocyanate, polytetrahydrofuran ether diol, silicone-modified hydroxyl-terminated polybutadiene and dibutyltin dilaurate, react, after reaction is completed, cool, add p-hydroxyanisole and hydroxyethyl acrylate, and continue to react to obtain polyurethane acrylate.

4. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 3, characterized in that, In step (1), when preparing the polyurethane acrylate: In S1, the molar ratio of hexafluorobutyl acrylate, mercaptoethanol and HDI trimer is 1:1.5-2:1; in the mixed solution of mercaptoethanol and triethylamine, the mass ratio of mercaptoethanol and triethylamine is 200:1; In preparing the hydroxyl fluorine-containing monomer, the drop condition of the mixed solution of mercaptoethanol and triethylamine is drop for 20-30min at 50℃, and the reaction condition is reaction for 8-10h at 50℃; In preparing the fluorine-containing isocyanate, the mass ratio of HDI trimer and catalyst dibutyltin dilaurate is 10:0.01, and the reaction condition is reaction for 1.5-2h at 70-80℃.

5. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 3, characterized in that, In the step (1) of preparing the polyurethane acrylate, in S2, in the preparation of the silane-modified hydroxyl-terminated polybutadiene, the solid-liquid ratio of the hydroxyl-terminated polybutadiene, KH590, tetrahydrofuran, and benzoin dimethyl ether is 10 g:2-2.5 g:300-350 mL:0.05 g, and the reaction condition is that the reaction is carried out under the condition of ultraviolet light with a wavelength of 365 nm and a power of 150 W for 3-4 h.

6. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 3, characterized in that, In the step (1) of preparing the polyurethane acrylate, in S2, in the preparation of the silane-modified hydroxyl-terminated polybutadiene, the solid-liquid ratio of the hydroxyl-terminated polybutadiene, KH590, tetrahydrofuran, and benzoin dimethyl ether is 10 g:2-2.5 g:300-350 mL:0.05 g, and the reaction condition is that the reaction is carried out under the condition of ultraviolet light with a wavelength of 365 nm and a power of 150 W for 3-4 h.

7. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 3, characterized in that, In the step (1) of preparing the polyurethane acrylate, in S2, in the preparation of the silane-modified hydroxyl-terminated polybutadiene, the solid-liquid ratio of the hydroxyl-terminated polybutadiene, KH590, tetrahydrofuran, and benzoin dimethyl ether is 10 g:2-2.5 g:300-350 mL:0.05 g, and the reaction condition is that the reaction is carried out under the condition of ultraviolet light with a wavelength of 365 nm and a power of 150 W for 3-4 h.

8. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 1, characterized in that, In the step (1), the preparation of the mercapto-functionalized graphene oxide comprises the following steps: The graphene oxide and water are mixed and ultrasonically dispersed for 20-30 min, and then heated to 50-60°C, and then 1.8 wt% sulfuric acid solution and mercaptoacetic acid are sequentially added, and then reacted at 50-60°C for 5 h, and then cooled, filtered, washed to neutral, and dried to obtain the mercapto-functionalized graphene oxide. In the step (1), the preparation of the mercapto-functionalized graphene oxide comprises the following steps:

9. The method for preparing the low-temperature resistant polyurethane transfer film according to claim 1, characterized in that, In the step (2), the adhesive layer is a hot melt adhesive film with a thickness of 0.15-0.3 mm, and the pressing condition is that the pressing is carried out under the condition of a temperature of 120-130°C and a pressure of 5-6 MPa.

10. A low-temperature-resistant polyurethane transfer film prepared by the method according to any one of claims 1-9.

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