Anti-sublimation clothing lettering film and preparation method thereof

Abstract

The invention relates to the technical field of lettering films, and particularly provides an anti-sublimation clothing lettering film and a preparation method thereof.The clothing lettering film sequentially comprises a PU surface layer, a PU middle layer, a contact layer, a TPU high-temperature layer and a hot melt adhesive layer from outside to inside, and the PU surface layer comprises polyurethane resin, color paste and modified graphene. The method comprises the following steps: preparing PU surface layer slurry, coating to form a surface layer, sequentially laminating a PU middle layer, a contact layer, a TPU high-temperature layer and a hot melt adhesive layer, and carrying out lamination treatment, wherein the preparation of the PU surface layer slurry comprises a graphene modification step. By introducing the modified graphene and the multi-layer structure design, the flexibility, the interlayer binding force and the adhesion durability of the lettering film are considered while the excellent anti-sublimation performance is ensured, and balanced improvement of the comprehensive performance is achieved.

Description

Technical Field

[0001] This invention belongs to the field of clothing decoration materials technology, specifically relating to an anti-sublimation clothing lettering film and its preparation method. Background Technology

[0002] Anti-sublimation heat transfer film is a widely used heat transfer material for personalized decoration in sportswear, casual wear, workwear, and other garments. It primarily uses a heat-pressing process to transfer multiple layers of polymer composite film onto the fabric surface, forming text, patterns, or logos. Heat transfer film typically consists of a top layer, an intermediate layer, and an adhesive layer. The top layer provides color and appearance, the intermediate layer enhances mechanical properties, and the adhesive layer ensures adhesion to the fabric. In practical applications, traditional heat transfer film is prone to sublimation, where dye or pigment molecules migrate under humid and hot conditions, leading to blurred patterns, color bleeding, or fading, severely affecting the garment's appearance and lifespan. This defect is particularly pronounced in dark-colored clothing or high-temperature environments such as during exercise, sweating, washing, and drying.

[0003] Existing technologies for addressing sublimation prevention typically employ methods such as adding anti-migration agents or optimizing the layered structure. For example, some solutions add organosilicon compounds or fluorocarbon resins as a barrier in the surface layer. These materials can block dye migration to some extent, but they suffer from high cost and poor flexibility; excessive addition can cause the lettering film to become brittle, affecting adhesion. Other methods use nanomaterials such as titanium dioxide or zinc oxide particles dispersed in polymers to prevent sublimation through physical barriers. However, nanoparticles are prone to agglomeration and uneven dispersion, which can introduce new defects such as surface roughness or interlayer delamination.

[0004] Other technologies employ multi-layer composite designs, such as adding a high-temperature TPU layer to improve heat resistance, but the interlayer bonding is insufficient, making them prone to peeling after repeated stretching or washing. Furthermore, some existing technologies attempt to introduce graphene materials, utilizing their high barrier properties; however, graphene has poor compatibility with the polymer matrix, and unmodified graphene tends to aggregate, affecting the uniformity and processing performance of the lettering film. Moreover, the preparation process is complex and costly. Overall, existing anti-sublimation lettering films struggle to balance color migration prevention, processing flexibility, and economy, often resulting in trade-offs. For example, excessive pursuit of anti-sublimation can increase the film's hardness, reducing clothing comfort; while focusing on flexibility may sacrifice protective effects. Therefore, there is an urgent need in this field for a novel lettering film that can effectively prevent color migration while maintaining good flexibility, adhesion, and processing performance, all at a controllable cost.

[0005] Therefore, it is necessary to design an anti-sublimation printing film for clothing and its preparation method. Summary of the Invention

[0006] To overcome the shortcomings of the existing technology, an anti-sublimation clothing lettering film and its preparation method are provided.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an anti-sublimation clothing lettering film, comprising, from the outside to the inside, a PU surface layer, a PU intermediate layer, a contact layer, a TPU high-temperature layer, and a hot melt adhesive layer, in parts by weight: The PU surface layer comprises 50-80 parts of polyurethane resin, 10-30 parts of color paste, and 2-8 parts of modified graphene. The PU intermediate layer comprises 60-90 parts of polyurethane resin and 5-15 parts of plasticizer; The contact layer comprises 75-105 parts of polyurethane resin and 2-7 parts of crosslinking agent; The TPU high-temperature layer comprises 50-90 parts of polyether-type thermoplastic polyurethane; The hot melt adhesive layer comprises 60-100 parts of polyurethane hot melt adhesive and 20-50 parts of liquid crystal polyurethane.

[0008] Preferably, the plasticizer includes diethylene glycol dibenzoate and 1,2-propanediol dibenzoate.

[0009] Preferably, the mass ratio of diethylene glycol dibenzoate to 1,2-propanediol dibenzoate is 5:(2-8).

[0010] Preferably, the crosslinking agent is an aziridine crosslinking agent.

[0011] Preferably, the aziridine crosslinking agent is 1-aziridine propionate.

[0012] Preferably, the method for preparing the modified graphene includes: S1. Acidification process: Graphene is mixed with acid solution and reacted at 50-80℃ for 1-5 hours to obtain acidified graphene. S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 40-80℃ to obtain the dried acidified graphene. S3. Surface grafting process: The dried acidified graphene, grafting agent and solvent are mixed and reacted at 60-90℃ for 1-3 hours to obtain surface-grafted graphene. S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

[0013] Preferably, in the acidification process, the acid solution is nitric acid with a concentration of 10-30%; the acidification process is accompanied by stirring at a speed of 100-300 rpm. In the surface grafting process, the grafting agent is a silane coupling agent or toluene diisocyanate. The surface grafting process is carried out under the protection of an inert gas, which is either nitrogen or argon. In the surface grafting process, the solvent is dimethylformamide or methylpyrrolidone.

[0014] Preferably, the silane coupling agent is γ-ureopropyltriethoxysilane.

[0015] This invention also provides a method for preparing an anti-sublimation clothing lettering film, which includes the following steps: S10. Mix the raw materials of the PU surface layer to obtain the PU surface layer slurry; coat the PU surface layer slurry on the release paper, and dry and cure to form the PU surface layer; S20. A PU intermediate layer, a contact layer, a TPU high-temperature layer, and a hot melt adhesive layer are sequentially laminated on the PU surface layer, and then laminated to obtain an anti-sublimation clothing lettering film.

[0016] Preferably, when preparing the PU surface layer slurry, the modified graphene and color paste are premixed first, and then polyurethane resin is added. The premixing time is 10-30 minutes. The coating is applied using a blade coating method, with the coating thickness controlled at 0.05-0.2 mm and the drying temperature at 60-100℃. The lamination process is carried out at a pressure of 0.5-2 MPa, a temperature of 100-150°C, and a time of 30-120 seconds.

[0017] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention improves the anti-sublimation performance by introducing modified graphene into the PU surface layer. The modified graphene, after acidification and surface grafting treatment, forms a uniformly dispersed composite structure with polyurethane resin, which can effectively block the migration of dye molecules in a humid and hot environment, thereby preventing pattern blurring and color bleeding, while avoiding the brittleness problem caused by traditional anti-migration agents.

[0018] 2. The plasticizer in the PU intermediate layer of this invention enhances the flexibility of the molecular chain, enabling the lettering film to maintain good elasticity when stretched or bent, thus reducing the risk of cracking.

[0019] 3. Regarding interlayer bonding, the contact layer of this invention uses a aziridine-based crosslinking agent to form a stable chemical crosslinking network, which improves the adhesion between layers. This design overcomes the defect of easy peeling between layers in the prior art, ensuring the structural integrity of the lettering film after repeated washing or hot pressing.

[0020] 4. The combination of the TPU high-temperature layer and the hot melt adhesive layer of the present invention further improves heat resistance and adhesion performance. The introduction of liquid crystal polyurethane into the hot melt adhesive layer enhances the wetting and bonding strength with the fabric surface, allowing the lettering film to remain firmly attached even under high-temperature environments such as drying or sweating during exercise, preventing it from falling off.

[0021] 5. Modified graphene improves dispersibility, reduces nanoparticle agglomeration, and enhances the smoothness and consistency of the surface layer; lamination is carried out under appropriate temperature and pressure to ensure tight fusion between layers, reduce production defects, and thus control costs while ensuring performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of an anti-sublimation clothing lettering film according to the present invention.

[0023] The markings in the diagram are: 1. PU top layer; 2. PU intermediate layer; 3. Contact layer; 4. TPU high-temperature layer; 5. Hot melt adhesive layer. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the specific embodiments of this application, the sources of various main raw materials are briefly described as follows: Polyurethane resin and diethylene benzoate: purchased from Wanhua Chemical Group Co., Ltd. Colorant: Purchased from BASF (China) Co., Ltd.; Graphene: Purchased from Jinan Moxi New Materials Technology Co., Ltd. 1,2-Propanediol dibenzoate: purchased from Shenzhen Ruijite Biotechnology Co., Ltd.; 1-Aziridine propionate (aziridine derivative): purchased from Wuhan Qianglong Chemical New Materials Co., Ltd.; Polyether-type thermoplastic polyurethane (TPU high-temperature layer): purchased from Meiri New Materials Co., Ltd.; Polyurethane hot melt adhesive: purchased from Dow Chemical (China) Investment Co., Ltd.; Liquid crystal polyurethane: purchased from Tosoh (Shanghai) Trading Co., Ltd.; γ-Uretopropyltriethoxysilane: purchased from Nanjing Shuguang Chemical Group Co., Ltd.; Dimethylformamide: purchased from Zhejiang Huafeng Chemical Co., Ltd.; Nitric acid: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0026] like Figure 1As shown, the technical solution of this application is: an anti-sublimation clothing lettering film, comprising, from the outside to the inside, a PU surface layer 1 (polyurethane surface layer), a PU intermediate layer 2 (polyurethane intermediate layer), a contact layer 3, a TPU high-temperature layer 4 (thermoplastic polyurethane high-temperature layer), and a hot melt adhesive layer 5, in parts by weight: The PU surface layer 1 comprises 50-80 parts of polyurethane resin, 10-30 parts of color paste, and 2-8 parts of modified graphene. The PU intermediate layer 2 comprises 60-90 parts of polyurethane resin and 5-15 parts of plasticizer; The contact layer 3 comprises 75-105 parts of polyurethane resin and 2-7 parts of crosslinking agent; The TPU high-temperature layer 4 comprises 50-90 parts of polyether-type thermoplastic polyurethane; The hot melt adhesive layer 5 comprises 60-100 parts of polyurethane hot melt adhesive and 20-50 parts of liquid crystal polyurethane.

[0027] In this application, the plasticizer preferably includes, but is not limited to, diethylene glycol dibenzoate and 1,2-propanediol dibenzoate.

[0028] In this application, the mass ratio of diethylene glycol dibenzoate to 1,2-propanediol dibenzoate is preferably, but not limited to, 5:(2-8).

[0029] In this application, the crosslinking agent is preferably, but not limited to, an aziridine crosslinking agent.

[0030] In this application, the aziridine crosslinking agent is preferably, but not limited to, 1-aziridine propionate.

[0031] In this application, the preferred, but not limited, method for preparing the modified graphene includes: S1. Acidification process: Graphene is mixed with acid solution and reacted at 50-80℃ for 1-5 hours to obtain acidified graphene. S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 40-80℃ to obtain the dried acidified graphene. S3. Surface grafting process: The dried acidified graphene, grafting agent and solvent are mixed and reacted at 60-90℃ for 1-3 hours to obtain surface-grafted graphene. S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

[0032] In this application, in the acidification process, the acid solution is preferably, but not limited to, nitric acid with a concentration of 10-30%; the acidification process is accompanied by stirring at a speed of 100-300 rpm. In the surface grafting process, the grafting agent is preferably, but not limited to, a silane coupling agent or toluene diisocyanate. The surface grafting process is carried out under the protection of an inert gas, which is preferably, but not limited to, nitrogen or argon. In the surface grafting process, the solvent is preferably, but not limited to, dimethylformamide or methylpyrrolidone.

[0033] Preferably, the silane coupling agent is, but not limited to, γ-ureopropyltriethoxysilane.

[0034] This application also provides a method for preparing an anti-sublimation clothing lettering film, which includes the following steps: S10. Mix the raw materials of PU surface layer 1 to obtain PU surface layer slurry; coat the PU surface layer slurry on the release paper, and dry and cure to form PU surface layer 1; S20. PU intermediate layer 2, contact layer 3, TPU high-temperature layer 4 and hot melt adhesive layer 5 are sequentially laminated on PU surface layer 1, and then laminated to obtain anti-sublimation clothing lettering film.

[0035] In this application, when preparing the PU surface layer slurry, the modified graphene and color paste are premixed first, and then polyurethane resin is added. The premixing time is 10-30 minutes. The coating is preferably, but not limited to, using a blade coating method, with the coating thickness controlled at 0.05-0.2 mm and the drying temperature at 60-100℃; The lamination process is carried out at a pressure of 0.5-2 MPa, a temperature of 100-150°C, and a time of 30-120 seconds.

[0036] The present invention will be described in detail below through examples and comparative examples, but the scope of protection of the present invention is not limited to these examples. Unless otherwise specified, the chemical reagents and raw materials used in the following examples and comparative examples are all conventional commercially available products.

[0037] Example 1: As Figure 1 As shown, an anti-sublimation lettering film for clothing comprises, from the outside to the inside, a PU surface layer 1, a PU intermediate layer 2, a contact layer 3, a TPU high-temperature layer 4, and a hot melt adhesive layer 5, in parts by weight: The PU surface layer 1 comprises 80 parts of polyurethane resin, 20 parts of color paste, and 2 parts of modified graphene. The PU intermediate layer 2 comprises 90 parts of polyurethane resin and 10 parts of plasticizer; the plasticizer is composed of diethylene glycol dibenzoate and 1,2-propanediol dibenzoate in a mass ratio of 5:2. The contact layer 3 comprises 105 parts of polyurethane resin and 4 parts of crosslinking agent; the crosslinking agent is 1-aziridine propionate. The TPU high-temperature layer 4 comprises 50 parts of polyether-type thermoplastic polyurethane. The hot melt adhesive layer 5 comprises 100 parts of polyurethane hot melt adhesive and 35 parts of liquid crystal polyurethane.

[0038] In this embodiment, the method for preparing the modified graphene includes: S1. Acidification process: Graphene is mixed with 30% nitric acid and reacted at 80°C for 1 hour with a stirring speed of 100 rpm to obtain acidified graphene. S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 80°C to obtain the dried acidified graphene. S3. Surface grafting process: The dried acidified graphene, γ-ureidopropyltriethoxysilane and dimethylformamide are mixed and reacted at 90°C for 1 hour under nitrogen protection to obtain surface-grafted graphene. S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

[0039] This embodiment also provides a method for preparing an anti-sublimation clothing lettering film, which includes the following steps: S10. Mix the raw materials of PU surface layer 1 to obtain PU surface layer slurry; coat the PU surface layer slurry on the release paper, and dry and cure to form PU surface layer 1; S20. PU intermediate layer 2, contact layer 3, TPU high-temperature layer 4 and hot melt adhesive layer 5 are sequentially laminated on PU surface layer 1, and then laminated to obtain anti-sublimation clothing lettering film.

[0040] In this embodiment, when preparing the PU surface layer slurry, the modified graphene and color paste are premixed first, and then polyurethane resin is added. The premixing time is 10 minutes. The coating is applied using a blade coating method, with the coating thickness controlled at 0.2 mm and the drying temperature at 80°C. The lamination process is performed at a pressure of 2 MPa, a temperature of 125°C, and a time of 30 seconds.

[0041] Example 2: As Figure 1 As shown, an anti-sublimation lettering film for clothing comprises, from the outside to the inside, a PU surface layer 1, a PU intermediate layer 2, a contact layer 3, a TPU high-temperature layer 4, and a hot melt adhesive layer 5, in parts by weight: The PU surface layer 1 comprises 50 parts of polyurethane resin, 30 parts of color paste, and 5 parts of modified graphene. The PU intermediate layer 2 comprises 60 parts of polyurethane resin and 15 parts of plasticizer; the plasticizer is composed of diethylene glycol dibenzoate and 1,2-propanediol dibenzoate in a mass ratio of 5:8. The contact layer 3 comprises 75 parts of polyurethane resin and 7 parts of crosslinking agent; the crosslinking agent is 1-aziridine propionate. The TPU high-temperature layer 4 comprises 90 parts of polyether-type thermoplastic polyurethane; The hot melt adhesive layer 5 comprises 60 parts of polyurethane hot melt adhesive and 50 parts of liquid crystal polyurethane.

[0042] In this embodiment, the method for preparing the modified graphene includes: S1. Acidification process: Graphene is mixed with 10% nitric acid and reacted at 50°C for 5 hours with a stirring speed of 300 rpm to obtain acidified graphene. S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 40°C to obtain the dried acidified graphene. S3. Surface grafting process: The dried acidified graphene, toluene diisocyanate and methylpyrrolidone are mixed and reacted at 60°C for 3 hours under argon protection to obtain surface-grafted graphene. S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

[0043] This embodiment also provides a method for preparing an anti-sublimation clothing lettering film, which includes the following steps: S10. Mix the raw materials of PU surface layer 1 to obtain PU surface layer slurry; coat the PU surface layer slurry on the release paper, and dry and cure to form PU surface layer 1; S20. PU intermediate layer 2, contact layer 3, TPU high-temperature layer 4 and hot melt adhesive layer 5 are sequentially laminated on PU surface layer 1, and then laminated to obtain anti-sublimation clothing lettering film.

[0044] In this embodiment, when preparing the PU surface layer slurry, the modified graphene and color paste are premixed first, and then polyurethane resin is added. The premixing time is 30 minutes. The coating is applied using a blade coating method, with the coating thickness controlled at 0.05 mm and the drying temperature at 100°C. The lamination process is performed at a pressure of 0.5 MPa, a temperature of 150°C, and a time of 120 seconds.

[0045] Example 3: As Figure 1 As shown, an anti-sublimation lettering film for clothing comprises, from the outside to the inside, a PU surface layer 1, a PU intermediate layer 2, a contact layer 3, a TPU high-temperature layer 4, and a hot melt adhesive layer 5, in parts by weight: The PU surface layer 1 comprises 65 parts of polyurethane resin, 10 parts of color paste, and 8 parts of modified graphene. The PU intermediate layer 2 comprises 75 parts of polyurethane resin and 5 parts of plasticizer; the plasticizer is composed of diethylene glycol dibenzoate and 1,2-propanediol dibenzoate in a mass ratio of 5:5. The contact layer 3 comprises 90 parts of polyurethane resin and 2 parts of crosslinking agent; the crosslinking agent is 1-aziridine propionate. The TPU high-temperature layer 4 comprises 70 parts of polyether-type thermoplastic polyurethane; The hot melt adhesive layer 5 comprises 80 parts of polyurethane hot melt adhesive and 20 parts of liquid crystal polyurethane.

[0046] In this embodiment, the method for preparing the modified graphene includes: S1. Acidification process: Graphene is mixed with 20% nitric acid and reacted at 65°C for 3 hours with a stirring speed of 200 rpm to obtain acidified graphene. S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 60°C to obtain the dried acidified graphene. S3. Surface grafting process: The dried acidified graphene, γ-ureidopropyltriethoxysilane and dimethylformamide are mixed and reacted at 75°C for 2 hours under nitrogen protection to obtain surface-grafted graphene. S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

[0047] This embodiment also provides a method for preparing an anti-sublimation clothing lettering film, which includes the following steps: S10. Mix the raw materials of PU surface layer 1 to obtain PU surface layer slurry; coat the PU surface layer slurry on the release paper, and dry and cure to form PU surface layer 1; S20. PU intermediate layer 2, contact layer 3, TPU high-temperature layer 4 and hot melt adhesive layer 5 are sequentially laminated on PU surface layer 1, and then laminated to obtain anti-sublimation clothing lettering film.

[0048] In this embodiment, when preparing the PU surface layer slurry, the modified graphene and color paste are premixed first, and then polyurethane resin is added. The premixing time is 20 minutes. The coating is applied by a blade coating method, with the coating thickness controlled at 1 mm and the drying temperature at 60°C. The lamination process is performed at a pressure of 1 MPa, a temperature of 100°C, and a time of 75 seconds.

[0049] Comparative Example 1: Compared with Example 1, the PU surface layer of Comparative Example 1 does not contain modified graphene, but the other components and preparation process are the same.

[0050] Comparative Example 2: Compared with Example 2, no plasticizer was added to the PU interlayer of Comparative Example 2, while the other components and preparation process were the same.

[0051] Comparative Example 3: Compared with Example 3, no crosslinking agent was added to the contact layer of Comparative Example 3, while the other components and preparation process were the same.

[0052] Comparative Example 4: Compared with Example 1, the hot melt adhesive layer of Comparative Example 4 does not contain liquid crystal polyurethane, but only uses polyurethane hot melt adhesive, while other components and preparation processes are the same.

[0053] Comparative Example 5: Compared with Example 2, the graphene modification step was omitted in the preparation of Comparative Example 5, and unmodified graphene was used directly, while other components and processes were the same.

[0054] Comparative Example 6: Compared with Example 3, the lamination process temperature of Comparative Example 6 was reduced to 80°C, the pressure was reduced to 0.2 MPa, and the time was shortened to 10 seconds, while other components and processes remained the same.

[0055] Performance test results and analysis: The performance of the examples and comparative examples was evaluated using general testing methods: Anti-sublimation performance was assessed through a damp heat aging test, in which samples were placed in an environment of 70°C and 85% relative humidity for 24 hours, and the degree of color migration was observed; flexibility was assessed through a bending fatigue test, recording the number of cycles the sample underwent repeated bending until fracture; interlayer adhesion was assessed through a peel strength test, measuring the force required for interlayer peeling; heat resistance was assessed through thermogravimetric analysis, recording the weight loss rate at 150°C; adhesion was assessed through a cross-cut test, evaluating the area of ​​detachment after the lettering film adhered to the fabric. All tests were conducted under standard conditions, and the average of three tests was taken. The specific test results are shown in Table 1.

[0056] Table 1 Analysis of test results:

[0057] As shown in Table 1, Examples 1 to 3 exhibited excellent performance in terms of anti-sublimation properties, flexibility, interlayer bonding, heat resistance, and adhesion, while the comparative examples showed a decline in various indicators. For example, Examples 1 and 3 achieved an anti-sublimation performance rating of 1, indicating minimal color migration. This was attributed to the uniform dispersion of modified graphene in the PU surface layer, forming an effective barrier structure. Comparative Example 1, lacking modified graphene, had an anti-sublimation performance rating of 4, with significant color migration, validating the crucial role of modified graphene. Comparative Example 5, using unmodified graphene, also showed poor anti-sublimation performance, demonstrating that graphene modification is essential for improving dispersibility and barrier effect.

[0058] Test results show that, in terms of flexibility, Examples 1 to 3 all exceeded 14,000 bending cycles, while Comparative Example 2, lacking a plasticizer, saw its cycle count drop to 8,000. This indicates that the plasticizer significantly improves flexibility by enhancing molecular chain movement. In the interlayer bonding strength test, Examples 1 to 3 exhibited higher peel strength, while Comparative Example 3, lacking a crosslinking agent, showed a significant decrease in peel strength to 8 N / cm, resulting in easy interlayer peeling. This highlights the importance of aziridine crosslinking agents in forming chemical crosslinked networks.

[0059] Regarding heat resistance, Examples 1 to 3 showed low weight loss rates, while Comparative Example 4, lacking liquid crystal polyurethane in its hot melt adhesive layer, exhibited a weight loss rate as high as 4.5%, indicating that the liquid crystal polyurethane enhances thermal stability through its ordered molecular structure. In the adhesion test, Example 3 showed a peeling area of ​​only 4%, while Comparative Example 6, due to insufficient lamination process parameters, saw its peeling area increase to 10%, emphasizing the necessity of optimizing lamination conditions to ensure interlayer fusion and adhesion strength.

[0060] This application achieves a balanced improvement in overall performance by introducing modified graphene and a multilayer structure design, ensuring excellent anti-sublimation performance while also taking into account the flexibility, interlayer bonding and adhesion durability of the lettering film.

[0061] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A type of anti-sublimation printing film for clothing, characterized in that, From the outside in, it consists of a PU top layer, a PU intermediate layer, a contact layer, a TPU high-temperature layer, and a hot melt adhesive layer, in parts by weight: The PU surface layer comprises 50-80 parts of polyurethane resin, 10-30 parts of color paste, and 2-8 parts of modified graphene. The PU intermediate layer comprises 60-90 parts of polyurethane resin and 5-15 parts of plasticizer; The contact layer comprises 75-105 parts of polyurethane resin and 2-7 parts of crosslinking agent; The TPU high-temperature layer comprises 50-90 parts of polyether-type thermoplastic polyurethane; The hot melt adhesive layer comprises 60-100 parts of polyurethane hot melt adhesive and 20-50 parts of liquid crystal polyurethane.

2. The anti-sublimation printing film for clothing according to claim 1, characterized in that, The plasticizers include diethylene glycol dibenzoate and 1,2-propanediol dibenzoate.

3. The anti-sublimation printing film for clothing according to claim 2, characterized in that, The mass ratio of diethylene glycol dibenzoate to 1,2-propanediol dibenzoate is 5:(2-8).

4. The anti-sublimation printing film for clothing according to claim 1, characterized in that, The crosslinking agent is a aziridine crosslinking agent.

5. The anti-sublimation printing film for clothing according to claim 4, characterized in that, The aziridine crosslinking agent is 1-aziridine propionate.

6. The anti-sublimation printing film for clothing according to claim 1, characterized in that, The method for preparing the modified graphene includes: S1. Acidification process: Graphene is mixed with acid solution and reacted at 50-80℃ for 1-5 hours to obtain acidified graphene. S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 40-80℃ to obtain the dried acidified graphene. S3. Surface grafting process: The dried acidified graphene, grafting agent and solvent are mixed and reacted at 60-90℃ for 1-3 hours to obtain surface-grafted graphene. S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

7. The anti-sublimation printing film for clothing according to claim 6, characterized in that, In the acidification process, the acid solution is nitric acid with a concentration of 10-30%; the acidification process is accompanied by stirring at a speed of 100-300 rpm. In the surface grafting process, the grafting agent is a silane coupling agent or toluene diisocyanate. The surface grafting process is carried out under the protection of an inert gas, which is either nitrogen or argon. In the surface grafting process, the solvent is dimethylformamide or methylpyrrolidone.

8. The anti-sublimation printing film for clothing according to claim 7, characterized in that, The silane coupling agent is γ-ureopropyltriethoxysilane.

9. A method for preparing an anti-sublimation clothing lettering film, used to prepare an anti-sublimation clothing lettering film as described in any one of claims 1-6, characterized in that, Includes the following steps: S10. Mix the raw materials of the PU surface layer to obtain the PU surface layer slurry; coat the PU surface layer slurry on the release paper, and dry and cure to form the PU surface layer; S20. A PU intermediate layer, a contact layer, a TPU high-temperature layer, and a hot melt adhesive layer are sequentially laminated on the PU surface layer, and then laminated to obtain an anti-sublimation clothing lettering film.

10. The method for preparing the anti-sublimation printing film for clothing according to claim 9, characterized in that, When preparing PU surface layer slurry, first premix the modified graphene with the color paste, and then add the polyurethane resin. The premixing time is 10-30 minutes. The coating is applied using a blade coating method, with the coating thickness controlled at 0.05-0.2 mm and the drying temperature at 60-100℃. The lamination process is carried out at a pressure of 0.5-2 MPa, a temperature of 100-150°C, and a time of 30-120 seconds.

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