A sublimation-proof clothing lettering film and a preparation method thereof

Abstract

The present application relates to the technical field of lettering film, and specifically provides a sublimation-proof clothing lettering film and a preparation method thereof. The clothing lettering film comprises, from outside to inside, a PU surface layer, a PU intermediate layer, a contact layer, a TPU high-temperature layer and a hot melt adhesive layer. The PU surface layer comprises polyurethane resin, color paste and modified graphene. The method comprises the following steps: preparing a PU surface layer paste, coating to form a surface layer, sequentially stacking a PU intermediate layer, a contact layer, a TPU high-temperature layer and a hot melt adhesive layer, and performing lamination treatment. The preparation of the PU surface layer paste comprises a graphene modification step. By introducing modified graphene and a multi-layer structure design, the present application ensures excellent sublimation-proof performance, and also takes into account the flexibility, interlayer bonding force and adhesion durability of the lettering film, so as to achieve balanced improvement in comprehensive performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of clothing decoration materials, and particularly relates to a sublimation-resistant clothing lettering film and a preparation method thereof. BACKGROUND

[0002] The sublimation-resistant clothing lettering film is a heat transfer material widely used in the personalized decoration field of sports clothes, casual clothes, work clothes and the like. The film is mainly transferred to the surface of a fabric through a hot pressing method to form characters, patterns or marks. The lettering film is usually composed of a surface layer, an intermediate layer and an adhesive layer. The surface layer is responsible for providing color and appearance, the intermediate layer enhances the mechanical properties, and the adhesive layer ensures adhesion to the fabric. In actual application, the conventional lettering film is prone to sublimation, i.e., dye or pigment molecules migrate under humid and hot conditions, resulting in blurred patterns, color bleeding or discoloration, which seriously affects the appearance and service life of the clothes. This defect is particularly prominent in dark clothes or high-temperature environments such as sports sweating, washing and drying.

[0003] To solve the problem of sublimation, the prior art usually adopts the method of adding a migration-preventing agent or optimizing the layered structure. For example, some schemes add silicone compounds or fluorocarbon resins as a barrier in the surface layer. These materials can block the migration of dyes to a certain extent, but have the problems of high cost and poor flexibility. Excessive addition will cause the lettering film to become brittle, affecting the adhesion. Some other methods use nano materials such as titanium dioxide or zinc oxide particles dispersed in polymers to prevent sublimation in a physical barrier manner, but the nano particles are prone to agglomeration and uneven dispersion, which introduces new defects such as surface roughness or interlayer delamination.

[0004] Some other technologies adopt a multi-layer composite design, such as adding a TPU high-temperature layer to improve heat resistance, but the interlayer bonding force is insufficient, and the film is prone to peeling after repeated stretching or washing. In addition, some prior art attempts to introduce graphene materials to take advantage of their high barrier properties, but the compatibility of graphene with the polymer matrix is poor. Unmodified graphene is prone to aggregation, affecting the uniformity and processing performance of the lettering film, and the preparation process is complex and costly. Overall, the existing sublimation-resistant lettering film is difficult to balance the effects of color migration prevention, processing flexibility and economy, and often sacrifices one for the other. For example, excessive pursuit of sublimation resistance leads to increased hardness of the lettering film, reducing the comfort of the clothes, while focusing on flexibility may sacrifice the protective effect. Therefore, there is an urgent need in the art for a new type of lettering film that can efficiently prevent color migration while maintaining good flexibility, adhesion and processing performance, and is cost-effective.

[0005] Therefore, it is necessary to design a sublimation-resistant clothing lettering film and a preparation method thereof. SUMMARY

[0006] In order to overcome the defects in the prior art, a sublimation-resistant clothing lettering film and a preparation method thereof are provided.

[0007] To achieve the above object, the present application provides the following technical solutions: a sublimation-proof clothing lettering film, which comprises, from outside to inside, a PU surface layer, a PU intermediate layer, a contact layer, a TPU high-temperature layer and a hot melt adhesive layer, in terms of mass parts:

[0008] The PU surface layer comprises polyurethane resin 50-80 parts, color paste 10-30 parts and modified graphene 2-8 parts;

[0009] The PU intermediate layer comprises polyurethane resin 60-90 parts and plasticizer 5-15 parts;

[0010] The contact layer comprises polyurethane resin 75-105 parts and crosslinking agent 2-7 parts;

[0011] The TPU high-temperature layer comprises polyether type thermoplastic polyurethane 50-90 parts;

[0012] The hot melt adhesive layer comprises polyurethane hot melt adhesive 60-100 parts and liquid crystal type polyurethane 20-50 parts.

[0013] Preferably, the plasticizer comprises diethylene glycol dibenzoate and 1,2-propanediol dibenzoate.

[0014] Preferably, the mass ratio of diethylene glycol dibenzoate and 1,2-propanediol dibenzoate is 5:(2-8).

[0015] Preferably, the crosslinking agent is a aziridine crosslinking agent.

[0016] Preferably, the aziridine crosslinking agent is 1-aziridine propionic acid ester.

[0017] Preferably, the preparation method of the modified graphene comprises:

[0018] S1, an acidizing process: mixing graphene with acid liquid and reacting at 50-80°C for 1-5 hours to obtain acidized graphene;

[0019] S2, a washing and drying process: washing the acidized graphene to neutral and drying at 40-80°C to obtain dried acidized graphene;

[0020] S3, a surface grafting process: mixing the dried acidized graphene, a grafting agent and a solvent and reacting at 60-90°C for 1-3 hours to obtain surface grafted graphene;

[0021] S4, a post-treatment process: washing and drying the surface grafted graphene to obtain modified graphene.

[0022] 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 revolutions per minute;

[0023] In the surface grafting process, the grafting agent is a silane coupling agent or toluene diisocyanate;

[0024] The surface grafting process is carried out under the protection of an inert gas, which is nitrogen or argon;

[0025] In the surface grafting process, the solvent is dimethylformamide or methylpyrrolidone.

[0026] Preferably, the silane coupling agent is gamma-ureidopropyl triethoxysilane.

[0027] The application also provides a method for preparing a sublimation-resistant clothing lettering film, which comprises the following steps:

[0028] S10, mixing the raw materials of the PU surface layer to obtain PU surface layer slurry; coating the PU surface layer slurry on release paper and drying and curing to form a PU surface layer;

[0029] S20, sequentially stacking a PU intermediate layer, a contact layer, a TPU high-temperature layer and a hot melt adhesive layer on the PU surface layer and performing lamination treatment to obtain a sublimation-resistant clothing lettering film.

[0030] Preferably, when preparing the PU surface layer slurry, the modified graphene is pre-mixed with the color paste first, and then the polyurethane resin is added, and the pre-mixing time is 10-30 minutes;

[0031] The coating is performed by using a doctor blade method, the coating thickness is controlled to be 0.05-0.2 millimeters, and the drying temperature is 60-100 DEG C;

[0032] The lamination treatment is performed at a pressure of 0.5-2 MPa, a temperature of 100-150 DEG C and a time of 30-120 seconds.

[0033] Compared with the prior art, the application has the following advantages and beneficial effects:

[0034] 1. The application improves the sublimation resistance of the PU surface layer by introducing modified graphene, which is uniformly dispersed in the polyurethane resin after acidification and surface grafting treatment, effectively preventing the migration of dye molecules in a humid and hot environment, thereby preventing pattern blurring and color bleeding, and avoiding the brittleness problem caused by traditional anti-migration agents.

[0035] 2. The plasticizer in the PU intermediate layer enhances the flexibility of the molecular chain, so that the lettering film maintains good elasticity when stretched or bent, reducing the risk of cracking.

[0036] 3. In terms of interlayer bonding, the contact layer of the present application uses aziridine crosslinking agent to form a stable chemical crosslinking network, improving 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.

[0037] 4. The combination of TPU high temperature layer and hot melt adhesive layer of the present application further improves the heat resistance and adhesion performance. The introduction of liquid crystal type polyurethane in the hot melt adhesive layer enhances the infiltration and bonding strength with the fabric surface, so that the lettering film can still adhere firmly in high temperature environment such as drying or sports sweating, avoiding falling off.

[0038] 5. The dispersion is improved by modifying graphene, reducing the agglomeration of nanoparticles, and improving the smoothness and consistency of the surface layer; Laminating treatment is carried out at appropriate temperature and pressure to ensure the close fusion between layers, reduce production defects, and thus control the cost while ensuring the performance. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A structure diagram of a sublimation-resistant clothing lettering film of the present application.

[0040] Marked in the figure: 1, PU surface layer; 2, PU middle layer; 3, contact layer; 4, TPU high temperature layer; 5, hot melt adhesive layer. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0042] In the specific implementation of the present application, the sources of various main raw materials are briefly described as follows:

[0043] Polyurethane resin, diethylene glycol dibenzoate: purchased from Wanhua Chemical Group Co., Ltd.;

[0044] Color paste: purchased from BASF (China) Co., Ltd.;

[0045] Graphene: purchased from Jinan Mexi New Material Technology Co., Ltd.;

[0046] 1,2-propanediol dibenzoate: purchased from Shenzhen Ruigite Biological Technology Co., Ltd.;

[0047] 1-aziridine propionate (aziridine): purchased from Wuhan Qianglong New Material Co., Ltd.;

[0048] Polyether thermoplastic polyurethane (TPU high temperature layer): purchased from Meisheng New Material Co., Ltd.

[0049] Polyurethane hot melt adhesive: purchased from Dow Chemical (China) Investment Co., Ltd.

[0050] Liquid crystal type polyurethane: purchased from Eastech (Shanghai) Trading Co., Ltd.

[0051] Gamma-ureido propyl triethoxysilane: purchased from Nanjing Shuguang Chemical Group Co., Ltd.

[0052] Dimethylformamide: purchased from Zhejiang Huafeng Chemical Co., Ltd.

[0053] Nitric acid: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0054] As shown in Figure 1 The technical solution of the present application is: a sublimation-proof clothing lettering film, which comprises, 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 terms of mass parts:

[0055] The PU surface layer 1 comprises polyurethane resin 50-80 parts, color paste 10-30 parts, and modified graphene 2-8 parts.

[0056] The PU intermediate layer 2 comprises polyurethane resin 60-90 parts and plasticizer 5-15 parts.

[0057] The contact layer 3 comprises polyurethane resin 75-105 parts and crosslinking agent 2-7 parts.

[0058] The TPU high temperature layer 4 comprises polyether thermoplastic polyurethane 50-90 parts.

[0059] The hot melt adhesive layer 5 comprises polyurethane hot melt adhesive 60-100 parts and liquid crystal type polyurethane 20-50 parts.

[0060] In the present application, the plasticizer preferably but not limitedly comprises diethylene glycol dibenzoate and 1,2-propanediol dibenzoate.

[0061] In the present application, the mass ratio of diethylene glycol dibenzoate and 1,2-propanediol dibenzoate is preferably but not limitedly 5:(2-8).

[0062] In the present application, the crosslinking agent is preferably but not limitedly a aziridine crosslinking agent.

[0063] In the present application, the aziridine crosslinking agent is preferably but not limitedly 1-aziridine propionate.

[0064] In the present application, the preparation method of the modified graphene preferably but not limited to includes:

[0065] S1, acidizing step: mixing graphene with acid solution, reacting at 50-80℃ for 1-5 hours to obtain acidized graphene;

[0066] S2, washing and drying step: washing the acidized graphene to neutral and drying at 40-80℃ to obtain dried acidized graphene;

[0067] S3, surface grafting step: mixing the dried acidized graphene, grafting agent and solvent, reacting at 60-90℃ for 1-3 hours to obtain surface grafted graphene;

[0068] S4, post-treatment step: washing and drying the surface grafted graphene to obtain modified graphene.

[0069] In the present application, in the acidizing step, the acid solution is preferably but not limited to 10-30% concentrated nitric acid; stirring is accompanied during the acidizing process, and the stirring speed is 100-300 rpm;

[0070] In the surface grafting step, the grafting agent is preferably but not limited to silane coupling agent or toluene diisocyanate;

[0071] The surface grafting step is carried out under inert gas protection, and the inert gas is preferably but not limited to nitrogen or argon;

[0072] In the surface grafting step, the solvent is preferably but not limited to dimethylformamide or methylpyrrolidone.

[0073] Preferably, the silane coupling agent is preferably but not limited to γ-ureidopropyl triethoxysilane.

[0074] The present application also provides a preparation method of a sublimation-resistant clothing lettering film, which is used to prepare the sublimation-resistant clothing lettering film and includes the following steps:

[0075] S10, mixing raw materials of PU surface layer 1 to obtain PU surface layer slurry; coating the PU surface layer slurry on release paper and drying and curing to form PU surface layer 1;

[0076] S20, sequentially stacking PU intermediate layer 2, contact layer 3, TPU high-temperature layer 4 and hot melt adhesive layer 5 on the PU surface layer 1 and performing lamination treatment to obtain the sublimation-resistant clothing lettering film.

[0077] In the present application, when preparing the PU surface layer slurry, the modified graphene is first pre-mixed with color paste, and then polyurethane resin is added, and the pre-mixing time is 10-30 minutes;

[0078] 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℃;

[0079] 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.

[0080] 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.

[0081] Example 1: As Figure 1 As shown, an anti-sublimation clothing lettering film 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:

[0082] The PU surface layer 1 comprises 80 parts of polyurethane resin, 20 parts of color paste, and 2 parts of modified graphene.

[0083] 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.

[0084] The contact layer 3 comprises 105 parts of polyurethane resin and 4 parts of crosslinking agent; the crosslinking agent is 1-aziridine propionate.

[0085] The TPU high-temperature layer 4 comprises 50 parts of polyether-type thermoplastic polyurethane.

[0086] The hot melt adhesive layer 5 comprises 100 parts of polyurethane hot melt adhesive and 35 parts of liquid crystal polyurethane.

[0087] In this embodiment, the method for preparing the modified graphene includes:

[0088] 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.

[0089] S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 80°C to obtain the dried acidified graphene.

[0090] 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.

[0091] S4, a post-processing step: washing and drying the surface grafted graphene to obtain the modified graphene.

[0092] The embodiment also provides a preparation method of the anti-sublimation garment lettering film.

[0093] S10, mixing raw materials of the PU surface layer 1 to obtain PU surface layer slurry; coating the PU surface layer slurry on release paper and drying and curing to form the PU surface layer 1;

[0094] S20, sequentially stacking the PU intermediate layer 2, the contact layer 3, the TPU high-temperature layer 4 and the hot melt adhesive layer 5 on the PU surface layer 1 and performing lamination treatment to obtain the anti-sublimation garment lettering film.

[0095] In the embodiment, when preparing the PU surface layer slurry, the modified graphene is pre-mixed with the color paste, and then the polyurethane resin is added, and the pre-mixing time is 10 minutes.

[0096] The coating adopts a doctor blade coating method, the coating thickness is controlled to be 0.2 mm, and the drying temperature is 80°C.

[0097] The lamination treatment has a pressure of 2 MPa, a temperature of 125°C and a time of 30 seconds.

[0098] Embodiment 2: as shown in the following table, an anti-sublimation garment lettering film sequentially includes 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 by mass fraction: Figure 1 The PU surface layer 1 includes polyurethane resin 50 parts, color paste 30 parts and modified graphene 5 parts;

[0099] The PU intermediate layer 2 includes polyurethane resin 60 parts and plasticizer 15 parts; the plasticizer is composed of diphenic acid diethylene glycol ester and diphenic acid 1,2-propanediol ester in a mass ratio of 5:8;

[0100] The contact layer 3 includes polyurethane resin 75 parts and crosslinking agent 7 parts; the crosslinking agent is 1-aziridine propionic acid ester;

[0101] The TPU high-temperature layer 4 includes polyether type thermoplastic polyurethane 90 parts;

[0102] The hot melt adhesive layer 5 includes polyurethane hot melt adhesive 60 parts and liquid crystal type polyurethane 50 parts.

[0103] In the embodiment, the preparation method of the modified graphene includes:

[0104]

[0105] ​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.

[0106] S2. Washing and drying process: The acidified graphene is washed until neutral and dried at 40°C to obtain the dried acidified graphene.

[0107] 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.

[0108] S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

[0109] This embodiment also provides a method for preparing an anti-sublimation clothing lettering film, which includes the following steps:

[0110] 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;

[0111] 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.

[0112] 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.

[0113] 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.

[0114] The lamination process is performed at a pressure of 0.5 MPa, a temperature of 150°C, and a time of 120 seconds.

[0115] Example 3: As Figure 1 As shown, an anti-sublimation clothing lettering film 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:

[0116] The PU surface layer 1 comprises 65 parts of polyurethane resin, 10 parts of color paste, and 8 parts of modified graphene.

[0117] 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.

[0118] The contact layer 3 comprises polyurethane resin 90 parts, crosslinking agent 2 parts; the crosslinking agent is 1-aziridine propionic acid ester;

[0119] The TPU high temperature layer 4 comprises polyether type thermoplastic polyurethane 70 parts;

[0120] The hot melt adhesive layer 5 comprises polyurethane hot melt adhesive 80 parts, liquid crystal type polyurethane 20 parts.

[0121] In the embodiment, the preparation method of the modified graphene comprises:

[0122] S1, acidification process: mix graphene with 20% concentration nitric acid, react at 65℃ for 3 hours, stirring speed 200 revolutions per minute, to obtain acidified graphene;

[0123] S2, washing and drying process: wash the acidified graphene to neutral, and dry at 60℃, to obtain dried acidified graphene;

[0124] S3, surface grafting process: mix the dried acidified graphene, gamma-ureido propyl triethoxysilane and dimethyl formamide, react at 75℃ for 2 hours, under nitrogen protection, to obtain surface grafted graphene;

[0125] S4, post-treatment process: wash and dry the surface grafted graphene, to obtain modified graphene.

[0126] The embodiment also provides a preparation method of the anti-sublimation clothing lettering film.

[0127] S10, mix the raw materials of the PU surface layer 1 to obtain PU surface layer slurry; coat the PU surface layer slurry on release paper, dry and solidify to form the PU surface layer 1;

[0128] S20, stack the PU middle layer 2, the contact layer 3, the TPU high temperature layer 4 and the hot melt adhesive layer 5 on the PU surface layer 1 in sequence, and perform lamination treatment to obtain the anti-sublimation clothing lettering film.

[0129] In the embodiment, when preparing the PU surface layer slurry, the modified graphene is pre-mixed with color paste, and then polyurethane resin is added, and the pre-mixing time is 20 minutes;

[0130] The coating adopts the doctor blade coating method, the coating thickness is controlled to be 1mm, and the drying temperature is 60℃;

[0131] The lamination treatment pressure is 1MPa, the temperature is 100℃, and the time is 75 seconds.

[0132] Comparative Example 1:

[0133] Comparative Example 1 does not contain modified graphene in the PU face layer, other components and preparation process are the same as Example 1.

[0134] Comparative Example 2:

[0135] Comparative Example 2 does not add plasticizer in the PU intermediate layer, other components and preparation process are the same as Example 2.

[0136] Comparative Example 3:

[0137] Comparative Example 3 does not add crosslinking agent in the contact layer, other components and preparation process are the same as Example 3.

[0138] Comparative Example 4:

[0139] Comparative Example 4 does not contain liquid crystal type polyurethane in the hot melt adhesive layer, only uses polyurethane hot melt adhesive, other components and preparation process are the same as Example 1.

[0140] Comparative Example 5:

[0141] Comparative Example 5 omits the graphene modification step in the preparation, directly uses unmodified graphene, other components and process are the same as Example 2.

[0142] Comparative Example 6:

[0143] Comparative Example 6 reduces the lamination treatment temperature to 80℃, reduces the pressure to 0.2 MPa, and shortens the time to 10 seconds, other components and process are the same as Example 3.

[0144] Performance test results and analysis:

[0145] The performance of the examples and comparative examples is evaluated by general test methods: the anti-sublimation performance is evaluated by damp heat aging test, the sample is placed in an environment of 70℃ and relative humidity 85% for 24 hours, and the color migration degree is observed; the flexibility is tested by bending fatigue test, and the cycle number of the sample is recorded when it is repeatedly bent to break; the interlayer bonding force is tested by peeling strength, and the force value required for interlayer peeling is measured; the heat resistance is analyzed by thermal gravimetric analysis, and the weight loss rate at 150℃ is recorded; the adhesion is tested by grid test, and the falling area of the lettering film combined with the fabric is evaluated. All tests are carried out under standard environment, and the average value of three tests is taken, and the test results are shown in Table 1.

[0146] Table 1 Analysis test results:

[0147]

[0148] As can be seen from Table 1, Examples 1 to 3 all perform excellently in terms of anti-sublimation performance, flexibility, interlayer adhesion, heat resistance and adhesion, while the comparative examples show a decline in different indicators. For example, the anti-sublimation performance of Examples 1 and 3 is rated as level 1, indicating that there is little color migration, which is due to the uniform dispersion of modified graphene in the PU surface layer, forming an effective barrier structure. Comparative Example 1, which lacks modified graphene, has a sublimation performance of level 4, with obvious color migration, verifying the key role of modified graphene. Comparative Example 5 uses unmodified graphene, and the anti-sublimation performance is also poor, indicating that the modification of graphene is crucial for improving dispersion and barrier effect.

[0149] The test results show that in terms of flexibility, the bending cycle times of Examples 1 to 3 all exceed 14,000 times, while Comparative Example 2, which lacks a plasticizer, has a number of 8,000 times, indicating that the plasticizer significantly improves flexibility by enhancing molecular chain movement. In the interlayer adhesion test, Examples 1 to 3 have high peel strength, while Comparative Example 3, which lacks a crosslinking agent, has a peel strength that is significantly reduced to 8 N / cm, leading to easy peeling between layers, highlighting the importance of aziridine crosslinking agents in forming a chemical crosslinking network.

[0150] In terms of heat resistance, Examples 1 to 3 have a low weight loss rate, while Comparative Example 4, which lacks liquid crystal polyurethane in the hot melt adhesive layer, has a weight loss rate of 4.5%, indicating that liquid crystal polyurethane enhances thermal stability through an ordered molecular structure. In the adhesion test, Example 3 has a peeling area of only 4%, while Comparative Example 6, due to insufficient lamination process parameters, has a peeling area of 10%, emphasizing the necessity of optimizing lamination conditions to ensure interlayer fusion and adhesion strength.

[0151] The present application, by introducing modified graphene and a multi-layer structure design, ensures excellent anti-sublimation performance while also considering the flexibility, interlayer adhesion and adhesion durability of the engraved film, achieving a balanced improvement in overall performance.

[0152] The above describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

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 plasticizer comprises diethylene glycol dibenzoate and 1,2-propanediol dibenzoate in a mass ratio of 5:(2-8). The contact layer comprises 75-105 parts of polyurethane resin and 2-7 parts of crosslinking agent; the crosslinking agent is 1-aziridine propionate. 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. Methods for preparing modified graphene include: S1. Acidification process: Graphene is mixed with acid solution and reacted at 50-80℃ for 1-5 hours to obtain acidified graphene; the acid solution is nitric acid with a concentration of 10-30%; stirring is carried out during the acidification process at a stirring speed of 100-300 rpm. 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; the grafting agent is a silane coupling agent or toluene diisocyanate, and the solvent is dimethylformamide or methylpyrrolidone; the surface grafting process is carried out under inert gas protection, and the inert gas is nitrogen or argon. S4. Post-processing step: Wash and dry the surface-grafted graphene to obtain modified graphene.

2. The anti-sublimation printing film for clothing according to claim 1, characterized in that, The silane coupling agent is γ-ureopropyltriethoxysilane.

3. A method for preparing an anti-sublimation clothing lettering film, used to prepare the anti-sublimation clothing lettering film as described in any one of claims 1-2, 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.

4. The method for preparing the anti-sublimation clothing lettering film according to claim 3, 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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