Transfer printing film structure and pattern heat transfer printing method

Abstract

The invention discloses a transfer printing film structure and a pattern heat transfer printing method, and relates to the technical field of transfer printing films, the transfer printing film is applied to the surface of a 3C product through an innovative material formula and a preparation process, and complex and personalized texture decoration can be achieved; and adaptive comprehensive solutions can be provided for workpieces with different surface materials through the customized attributes of the structural layer. Meanwhile, according to the technical scheme and the related process, traditional anodic oxidation and ink spraying processes can be replaced on a large scale to be applied to surface treatment, and pollution to the environment and emission of harmful gas are avoided. The overall complexity of workpiece machining can be simplified, and the overall machining difficulty is lowered. In addition, according to the technical scheme, the transfer-printed film base material can be reused under some conditions or recycled in a recycling and reprocessing mode, the customization requirements of related industries are met, and meanwhile the environmental protection concept and the cost control requirement are met.

Description

Technical Field

[0001] The present invention relates to the technical field of transfer films, in particular to a transfer film structure and a pattern thermal transfer method. Background Art

[0002] At present, the shells of 3C electronic products on the market are becoming more and more beautiful, but many people do not know how they are produced. Only people in this field know that the traditional production process is through chemical treatment, such as anodizing and ink spraying. Such a production environment is not friendly to personnel or land ecological environment. Moreover, the traditional anodizing method has a relatively single color, and the spraying method has many processes, which are cumbersome and polluting. For this reason, we need to design an environmentally friendly transfer production method. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the present invention provides a transfer film structure and a pattern thermal transfer method, which solves the problem of environmental pollution. At the same time, there will be no chemical residues, and the processed waste products can be reused, solving the problem of environmental friendliness and the problem of duplication.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0005] In a first aspect, the present invention provides a transfer film structure, wherein the transfer film is a two-layer co-extruded structure, comprising:

[0006] a first texture layer, wherein one surface of the first texture layer has textures;

[0007] A first bright surface layer is provided on a side of the first texture layer that does not have textures.

[0008] Furthermore, the first texture layer is prepared from the following components in parts by weight: 60-80 parts of copolymerized polypropylene, 10-20 parts of EPDM elastomer, and 5-10 parts of spherical silica lubricating masterbatch.

[0009] Furthermore, the first bright surface layer is prepared from the following components in parts by weight: 70-90 parts of copolymerized polypropylene, 5-15 parts of EPDM elastomer, and 10-20 parts of polyethylene.

[0010] In a second aspect, the present invention provides a transfer film structure, wherein the transfer film is a three-layer co-extruded structure, comprising:

[0011] a second texture layer, wherein one surface of the second texture layer has textures;

[0012] a second bright surface layer, the second bright surface layer being provided on a side of the second textured layer that does not have textures;

[0013] The middle layer is arranged between the second texture layer and the second bright surface layer.

[0014] Furthermore, the second texture layer is prepared from the following components in parts by weight: 50-70 parts of homopolypropylene, 15-25 parts of EPDM elastomer, and 8-12 parts of spherical silica lubricating masterbatch.

[0015] Furthermore, the second bright surface layer is prepared from the following components in parts by weight: 65-85 parts of copolymerized polypropylene and 8-18 parts of EPDM elastomer.

[0016] Furthermore, the middle layer is prepared from the following components in parts by weight: 55-75 parts of copolymerized polypropylene, 12-22 parts of EPDM elastomer, and 15-25 parts of polyethylene.

[0017] The above-mentioned preparation method of the transfer film structure includes: mixing different polymer particles evenly according to the formula, pouring them into different extruder hoppers respectively, and extruding the melt to a distributor through high-temperature plasticization and shearing by the screw, and then flowing into the extrusion device; after the melt flows out of the extruder, it is thinned and formed by an embossing forming roller, and then cooled and shaped by air again, and then sent to a winding device after corona treatment, thereby completing the production of the transfer film structure.

[0018] In a third aspect, the present invention further provides a method for thermally transferring a pattern of a transfer film structure, comprising the following steps:

[0019] S1. Coating a release layer, a UV texture layer, a gloss enhancement layer, a printing layer, and an adhesive layer on the inner side of the transfer film in sequence to obtain a film for thermal transfer;

[0020] S2. Place the coated film flatly on the workbench of the thermal transfer equipment. At the same time, place the workpiece to be transferred at the corresponding position below the film. Start the equipment so that the transfer stage enters the mold closing position of the thermal transfer equipment and performs the mold closing operation to ensure that the film and workpiece are accurately positioned to avoid deviation of the transfer pattern.

[0021] S3. After the mold is closed, start the vacuum system of the thermal transfer equipment to evacuate the upper and lower cavities at the same time until the vacuum degree in the cavity reaches -0.098 MPa. The air in the cavity is removed by vacuuming to prevent the formation of bubbles during the thermal transfer process, which affects the quality of the transfer pattern and ensures the flatness and integrity of the transfer pattern.

[0022] S4. While maintaining the vacuum degree of the upper and lower cavities at -0.098 MPa, start the heating system of the thermal transfer equipment to heat the film, gradually heating the film to the pre-set transfer temperature. During the heating process, continuously monitor the film temperature to ensure that the temperature rises evenly to avoid local overheating that may damage the film or pattern, or insufficient temperature that may affect the melting and bonding effect of the adhesive layer;

[0023] S5. When the diaphragm temperature reaches the set temperature, the neutron plate of the thermal transfer equipment slowly lifts the workpiece to be transferred, so that the workpiece and the diaphragm gradually approach and finally fit tightly together; at the same time, high-pressure gas is filled into the upper cavity of the thermal transfer equipment, so that the pressure of the upper cavity reaches 0.2 MPa, while the lower cavity maintains a negative pressure of -0.098 MPa. This pressure difference can make the diaphragm fit better on the surface of the workpiece, especially for some workpieces with complex shapes or uneven surfaces. The pressure difference can ensure that the pattern is completely and accurately transferred to all parts of the workpiece;

[0024] S6. Enter the pressure holding stage, maintain the upper cavity pressure at 0.2 MPa, and the lower cavity maintains a negative pressure state of -0.098 MPa. During the pressure holding process, the adhesive layer fully melts and penetrates into the microstructure of the workpiece surface, so that the transfer pattern and the workpiece form a strong bond. At the same time, ensure that the UV texture layer, gloss enhancement layer and printing layer are closely combined with the workpiece, ensuring the quality and stability of the transfer pattern;

[0025] S7. After the pressure holding is completed, the exhaust system of the thermal transfer equipment is started to exhaust the upper and lower cavities at the same time until the pressure of the upper and lower cavities is 0. After the exhaust is completed, the thermal transfer equipment is opened and the workpiece after transfer is taken out. At this time, the pattern on the transfer film has been successfully transferred to the surface of the workpiece. The transfer film and release layer are peeled off. The release layer can smoothly separate the transfer film from the pattern to obtain a transfer product with a beautiful pattern.

[0026] The present invention provides a transfer film structure and a pattern thermal transfer method. Compared with the prior art, it has the following advantages:

[0027] 1. The technical solution of the patent of this invention replaces the traditional production process of anodizing and ink spraying, which will not pollute the environment and will not have a strong odor. The technical solution of this patent is to only print the pattern on the surface of the transfer film, and then make the transfer film layer to achieve transfer. This patent can print different patterns and different colors. The texture on the surface of the transferred product is also printed on the surface of the film. The transferred product looks layered. Moreover, the transferred film in the technical solution of this patent can continue to be used or reused through regeneration. This patented process is a subversive technological innovation to the traditional manufacturing process. There are revolutionary changes in both process and appearance, which solves the problem of pollution in the industry.

[0028] 2. The transfer film of the present invention has achieved a significant breakthrough in thermal stretching performance. Experimental testing has shown that, at a high temperature of 120°C, its tensile elongation at break is as high as 710%, far exceeding the 15% of ordinary polyolefin substrates. This outstanding performance enables it to easily withstand high-temperature tensile forces during the thermal transfer process, ensuring the integrity of the transfer film even when faced with complex shapes or large-format workpieces. For example, in the transfer of curved surfaces on electronic product casings, ordinary transfer films may break due to high-temperature stretching, resulting in missing patterns. However, the transfer film of the present invention, with its excellent thermal stretching ability, can completely conform to the curved surface, ensuring the continuity and integrity of the transferred pattern, greatly improving the quality and yield of the transferred products.

[0029] 3. The transfer film of the present invention performs exceptionally well in terms of high-temperature dimensional stability. After continuous baking at 85°C for 120 minutes, its warpage is still less than 5mm, while other thermal transfer films have warpage exceeding 50mm. In the thermal transfer process, good adhesion between the transfer film and the workpiece is crucial. The slight warpage of the transfer film of the present invention ensures a close fit with the workpiece surface, effectively avoiding the occurrence of problems such as bubbles and wrinkles. This allows for precise alignment of the transferred pattern, natural color transitions, and clear details, providing reliable guarantees for high-precision transfers.

[0030] 4. The patent of this invention solves the single color problem of traditional anodizing, and BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the transfer film of the present invention formed by a two-layer co-extrusion method;

[0032] Figure 2 Schematic diagram of the structure of the transfer film of the present invention formed by three-layer co-extrusion;

[0033] Figure 3 Schematic diagram of coating various layers of structure on the inner side of the transfer film in the present invention;

[0034] Figure 4 Schematic diagram of the structural changes during the pattern thermal transfer process of the present invention.

[0035] In the figure: 1. Transfer film; 11. First texture layer; 12. First glossy layer; 13. Second texture layer; 14. Second glossy layer; 15. Intermediate layer; 2. Release layer; 3. UV texture layer; 4. Brightening layer; 5. Printing layer; 6. Adhesive layer; 7. Workpiece. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Example 1

[0038] See also Figure 1 、 Figure 3 and Figure 4 This embodiment uses a two-layer co-extruded structure transfer film for surface pattern thermal transfer, as follows:

[0039] 1. Transfer Film Preparation

[0040] Raw material preparation

[0041] Raw materials for the first texture layer 11: Weigh 70 parts of copolymerized polypropylene, 15 parts of EPDM elastomer, and 7 parts of spherical silica lubricant masterbatch by weight, pour the three raw materials into a high-speed mixer, and mix them at a speed of 800 r / min for 10 minutes to ensure that the ingredients are evenly dispersed.

[0042] Raw materials for the first bright surface layer 12: Weigh 80 parts of copolymerized polypropylene, 10 parts of EPDM elastomer, and 15 parts of polyethylene, pour them into a high-speed mixer, and mix them at a speed of 800 r / min for 10 minutes.

[0043] Coextrusion

[0044] The mixed raw materials for the first texture layer 11 and the first glossy layer 12 are poured into different extruder hoppers. The temperatures of the extruder sections corresponding to the first texture layer 11 are set as follows: feeding section 180°C, compression section 200°C, metering section 220°C, and die head temperature 230°C; the temperatures of the extruder sections corresponding to the first glossy layer 12 are set as follows: feeding section 170°C, compression section 190°C, metering section 210°C, and die head temperature 220°C.

[0045] The raw material is plasticized and sheared by the screw at high temperature, extruded into a melt into a distributor, and then flows into the extruder. After flowing out of the extruder, the melt passes through an embossing roller and a bright roller. The embossing roller is set at 80°C and the bright roller is set at 70°C. It is then cooled again by air and shaped. The embossing roller is used to give the film surface texture, while the bright roller makes the other side of the film smooth.

[0046] The transfer film after shaping is subjected to corona treatment with a corona power set to 5kW to enhance the adhesion of the transfer film surface. Finally, it is sent to the winding device to obtain a transfer film with a two-layer co-extruded structure.

[0047] 2. Thermal transfer operation

[0048] Film Coating: A release layer 2, UV texture layer 3, gloss-enhancing layer 4, print layer 5, and adhesive layer 6 are sequentially applied to the first glossy layer 12 of the transfer film 1. Release layer 2 uses a silicone release agent and is applied to a thickness of 1 μm. UV texture layer 3 uses a UV-curable resin, applied through a mold with a specific texture, which forms a 5 μm-deep texture after curing. Gloss-enhancing layer 4 uses acrylic resin and is applied to a thickness of 3 μm. Print layer 5 uses ink to print the desired pattern with a resolution of 300 dpi. Adhesive layer 6 uses a hot-melt polyurethane adhesive and is applied to a thickness of 8 μm. This results in a film suitable for thermal transfer printing.

[0049] Placement and mold closing: Place the coated film flatly on the workbench of the thermal transfer equipment, and place the workpiece 7 to be transferred at the corresponding position below the film. Start the equipment and move the transfer table to the mold closing position of the thermal transfer equipment to perform the mold closing operation, ensuring that the film and workpiece positions are accurately aligned, with the error controlled within ±0.1mm.

[0050] Vacuuming: After the mold is closed, start the vacuum system of the thermal transfer equipment to vacuum the upper and lower cavities at the same time, and the vacuum degree in the cavity reaches -0.098 MPa within 30 seconds.

[0051] Heating: When the film is heated, the upper and lower air pressures are: upper cavity: -0.098~0.25mpa, lower cavity: -0.098~0.25mpa, start the heating system of the thermal transfer equipment to heat the film. The heating temperature is set to 150℃, and the heating time is 60 seconds.

[0052] During the heating process, the diaphragm temperature is continuously monitored by an infrared thermometer to ensure that the temperature rises evenly and the temperature fluctuation range is controlled within ±2℃.

[0053] High pressure filling and bonding: When the diaphragm temperature is heated to 150°C, the neutron plate of the thermal transfer equipment slowly lifts the workpiece to be transferred, so that the workpiece and the diaphragm gradually approach and finally fit tightly.

[0054] At the same time, high-pressure gas is filled into the upper cavity of the thermal transfer equipment, and the pressure of the upper cavity reaches 0.2 MPa within 10 seconds, while the lower cavity maintains a negative pressure of -0.098 MPa, so that the diaphragm can bend downward;.

[0055] Pressure holding: Entering the pressure holding stage, the upper cavity pressure is maintained at 0.2 MPa, the lower cavity is maintained in a negative pressure state of -0.098 MPa, and the pressure holding time is 90 seconds.

[0056] Exhaust and removal: After the pressure holding period is complete, the exhaust system of the thermal transfer equipment is activated to exhaust the upper and lower cavities simultaneously. The exhaust time is 20 seconds, until the pressure in both cavities is 0. After exhaust is complete, the thermal transfer equipment is opened, the transferred workpiece is removed, and the transfer film 1 and release layer 2 are peeled off to obtain a transfer product with a beautiful pattern.

[0057] Example 2

[0058] See also Figure 2 、 Figure 3 and Figure 4 This embodiment uses a three-layer co-extruded structure transfer film for surface pattern thermal transfer, as follows:

[0059] 1. Transfer Film Preparation

[0060] Raw material preparation

[0061] Raw materials for the second texture layer 13: 60 parts of homopolypropylene, 20 parts of EPDM elastomer, and 10 parts of spherical silica lubricating masterbatch were weighed by weight, poured into a high-speed mixer, and mixed at a speed of 900 r / min for 8 minutes.

[0062] Raw materials for the intermediate layer 15: Weigh 65 parts of copolymerized polypropylene, 17 parts of EPDM elastomer, and 20 parts of polyethylene, pour them into a high-speed mixer, and mix them at a speed of 900 r / min for 8 minutes.

[0063] Raw materials for the second bright surface layer 14: Weigh 75 parts of copolymerized polypropylene and 13 parts of EPDM elastomer, pour them into a high-speed mixer, and mix them at a speed of 900 r / min for 8 minutes.

[0064] Coextrusion

[0065] The mixed raw materials for the second texture layer 13, the middle layer 15, and the second bright surface layer 14 are poured into different extruder hoppers. The temperatures of the extruder sections corresponding to the second texture layer 13 are set as follows: feeding section 190°C, compression section 210°C, metering section 230°C, and die head temperature 240°C; the temperatures of the extruder sections corresponding to the middle layer 15 are set as follows: feeding section 180°C, compression section 200°C, metering section 220°C, and die head temperature 230°C; the temperatures of the extruder sections corresponding to the second bright surface layer 14 are set as follows: feeding section 175°C, compression section 195°C, metering section 215°C, and die head temperature 225°C.

[0066] The raw material is plasticized and sheared by the screw at high temperature, extruding the melt into a distributor and then into the extruder. After exiting the extruder, the melt passes through an embossing roller (set to 85°C for the embossing roller and 75°C for the glossy roller) and is air-cooled and shaped. The shaped transfer film undergoes corona treatment at a power of 6kW before being fed into a winder to produce a three-layer co-extruded transfer film.

[0067] 2. Thermal transfer operation

[0068] Film Coating: A release layer 2, UV texture layer 3, gloss-enhancing layer 4, print layer 5, and adhesive layer 6 are sequentially applied to the second glossy layer 14 of the transfer film 1. Release layer 2 uses a fluorine-based release agent and is applied to a thickness of 1.2 μm. UV texture layer 3 uses a UV-curable acrylic resin, applied through a mold with a specific texture, and after curing, forms a texture with a depth of 6 μm. Gloss-enhancing layer 4 is a polyester resin and is applied to a thickness of 4 μm. Print layer 5 is printed with ink to create the desired pattern with a resolution of 350 dpi. Adhesive layer 6 is a hot-melt ethylene-vinyl acetate copolymer adhesive and is applied to a thickness of 9 μm. This results in a film suitable for thermal transfer printing.

[0069] Placement and mold closing: Place the coated film flatly on the workbench of the thermal transfer equipment, and place the plastic workpiece 7 to be transferred at the corresponding position below the film. Start the equipment and move the transfer table to the mold closing position of the thermal transfer equipment to perform the mold closing operation, ensuring that the film and workpiece are accurately aligned, with the error controlled within ±0.08mm.

[0070] Vacuuming: After the mold is closed, start the vacuum system of the thermal transfer equipment to vacuum the upper and lower cavities at the same time, and the vacuum degree in the cavity reaches -0.098 MPa within 25 seconds.

[0071] Heating: While maintaining a vacuum of -0.098 MPa in the upper and lower chambers, the thermal transfer equipment's heating system was activated to heat the film. The heating temperature was set to 140°C for 70 seconds. During the heating process, the film temperature was continuously monitored using an infrared thermometer to ensure a uniform temperature rise and a temperature fluctuation range of ±1.5°C.

[0072] High-pressure filling and bonding: After the film is heated to 140°C, the heat transfer equipment's neutron plate slowly raises the plastic workpiece to be transferred, gradually bringing the workpiece and film closer together and ultimately bonding them tightly. Simultaneously, high-pressure gas is injected into the upper chamber of the heat transfer equipment, bringing the pressure to 0.2 MPa within 8 seconds, while the lower chamber maintains a negative pressure of -0.098 MPa.

[0073] Pressure holding: Entering the pressure holding stage, the upper cavity pressure is maintained at 0.2 MPa, the lower cavity is maintained in a negative pressure state of -0.098 MPa, and the pressure holding time is 100 seconds.

[0074] Exhaust and removal: After the pressure holding period is complete, the exhaust system of the thermal transfer equipment is activated to exhaust the upper and lower cavities simultaneously. The exhaust time is 18 seconds, until the pressure in both cavities is 0. After exhaust is complete, the thermal transfer equipment is opened, the transferred plastic workpiece is removed, and the transfer film 1 and release layer 2 are peeled off to obtain a plastic transfer product with a beautiful pattern.

[0075] Example 3

[0076] See also Figure 2 、 Figure 3 and Figure 4 This embodiment uses a three-layer co-extruded structure transfer film to perform thermal transfer of patterns on the glass surface, as follows:

[0077] 1. Transfer Film Preparation

[0078] Raw material preparation

[0079] Raw materials for the second texture layer 13: 55 parts of homopolypropylene, 22 parts of EPDM elastomer, and 8 parts of spherical silica lubricant masterbatch were weighed by weight, poured into a high-speed mixer, and mixed at a speed of 1000 r / min for 6 minutes.

[0080] Raw materials for the intermediate layer 15: Weigh 70 parts of copolymerized polypropylene, 15 parts of EPDM elastomer, and 18 parts of polyethylene, pour them into a high-speed mixer, and mix them at a speed of 1000 r / min for 6 minutes.

[0081] Raw materials for the second bright surface layer 14: Weigh 80 parts of copolymerized polypropylene and 10 parts of EPDM elastomer, pour them into a high-speed mixer, and mix them at a speed of 1000 r / min for 6 minutes.

[0082] Coextrusion

[0083] The mixed raw materials for the second texture layer 13, the middle layer 15, and the second bright surface layer 14 are poured into different extruder hoppers. The temperatures of the extruder sections corresponding to the second texture layer 13 are set as follows: feeding section 185°C, compression section 205°C, metering section 225°C, and die head temperature 235°C; the temperatures of the extruder sections corresponding to the middle layer 15 are set as follows: feeding section 175°C, compression section 195°C, metering section 215°C, and die head temperature 225°C; the temperatures of the extruder sections corresponding to the second bright surface layer 14 are set as follows: feeding section 170°C, compression section 190°C, metering section 210°C, and die head temperature 220°C.

[0084] The raw material is plasticized and sheared by the screw at high temperature, extruding the melt into a distributor and then into the extruder. After exiting the extruder, the melt passes through an embossing roller and a bright roller (the embossing roller is set at 90°C and the bright roller is set at 80°C), where it is cooled again by air and shaped. The shaped transfer film undergoes corona treatment at a power of 7kW and is finally fed into a winding device to produce a three-layer co-extruded transfer film.

[0085] 2. Thermal transfer operation

[0086] Film Coating: A release layer 2, UV texture layer 3, gloss-enhancing layer 4, printed layer 5, and adhesive layer 6 are sequentially applied to the second glossy layer 14 of the transfer film 1. Release layer 2 uses a non-silicone release agent and is applied to a thickness of 1.5 μm. UV texture layer 3 uses a UV-curable epoxy resin, applied through a mold with a specific texture, to form a texture with a depth of 7 μm after curing. Gloss-enhancing layer 4 is a polyurethane resin and is applied to a thickness of 5 μm. Printed layer 5 uses ink to print the desired pattern with a resolution of 400 dpi. Adhesive layer 6 is a hot-melt polyamide adhesive and is applied to a thickness of 10 μm. This results in a film suitable for thermal transfer.

[0087] Placement and mold closing: Place the coated film flatly on the workbench of the thermal transfer equipment, and place the glass workpiece 7 to be transferred at the corresponding position below the film. Start the equipment and move the transfer stage to the mold closing position of the thermal transfer equipment to perform the mold closing operation, ensuring that the film and workpiece positions are accurately aligned, with the error controlled within ±0.05mm.

[0088] Vacuuming: After the mold is closed, start the vacuum system of the thermal transfer equipment to vacuum the upper and lower cavities at the same time, and the vacuum degree in the cavity reaches -0.098 MPa within 20 seconds.

[0089] Heating: While maintaining a vacuum of -0.098 MPa in the upper and lower chambers, the thermal transfer equipment's heating system was activated to heat the film. The heating temperature was set to 130°C for 80 seconds. During the heating process, the film temperature was continuously monitored using an infrared thermometer to ensure a uniform temperature rise and a temperature fluctuation range of ±1°C.

[0090] High-pressure filling and bonding: After the film is heated to 130°C, the heat transfer equipment's neutron plate slowly raises the glass workpiece to be transferred, gradually bringing the workpiece and film closer together and ultimately bonding them tightly. Simultaneously, high-pressure gas is injected into the upper chamber of the heat transfer equipment, bringing the pressure to 0.2 MPa within 6 seconds, while the lower chamber maintains a negative pressure of -0.098 MPa.

[0091] Pressure holding: Entering the pressure holding stage, the upper cavity pressure is maintained at 0.2 MPa, the lower cavity is maintained in a negative pressure state of -0.098 MPa, and the pressure holding time is 110 seconds.

[0092] Exhaust and removal: After the pressure holding period is complete, the exhaust system of the thermal transfer equipment is activated to exhaust the upper and lower cavities simultaneously. The exhaust time is 15 seconds, until the pressure in both cavities is 0. After exhaust is complete, the thermal transfer equipment is opened, the transferred glass workpiece is removed, and the transfer film 1 and release layer 2 are peeled off to obtain a glass transfer product with a beautiful pattern.

[0093] The experimental test data of transfer film 1 are as follows:

[0094] I. Comparison of hot tensile test data of transfer film 1:

[0095]

[0096]

[0097] 1. Room-Temperature Tensile Properties: At room temperature, the thermal transfer film of this invention achieves a tensile elongation at break of 720%, a 70 percentage point improvement compared to the 650% achieved by conventional 150-micron polyolefin substrates. This demonstrates that, in typical use environments, the transfer film of this invention exhibits superior flexibility and ductility, adapting to more complex shapes and deformation requirements while reducing the risk of rupture due to stretching, thereby enhancing the film's applicability and reliability.

[0098] 2. High-Temperature Tensile Properties: At 120°C, the tensile elongation at break of conventional polyolefin substrates drops sharply to 15%, virtually losing their tensile properties. However, the thermal transfer film of the present invention maintains a high elongation at break of 710%, close to its performance at room temperature, demonstrating exceptional high-temperature stability. This characteristic is crucial for the thermal transfer process, as the film must withstand certain temperatures and tensile forces. The present transfer film maintains excellent tensile properties at high temperatures, ensuring that the quality and integrity of the transferred pattern are not affected by tensile deformation during the thermal transfer process, significantly improving the success rate of thermal transfer and product quality.

[0099] II. Comparison of warpage test data of transfer film 1:

[0100]

[0101]

[0102] 1. Room-Temperature Warpage: At room temperature, the warpage of other thermal transfer films is less than 10mm, while the thermal transfer film of this invention has a warpage of less than 5mm, demonstrating superior flatness. Good room-temperature flatness enhances the stability and convenience of the transfer film during storage, transportation, and use, reduces the problem of loose fit between the film and the workpiece caused by warpage, and improves transfer accuracy and efficiency.

[0103] 2. Warpage after high-temperature baking: After continuous baking at 85°C for 120 minutes, the warpage of other thermal transfer films increased significantly to more than 50 mm, while the warpage of the thermal transfer film of the present invention was still less than 5 mm, with almost no significant change. This result fully demonstrates the dimensional stability of the thermal transfer film of the present invention under high-temperature conditions. In the thermal transfer process, high-temperature treatment is an indispensable step. Other thermal transfer films will experience severe warping after high-temperature baking, which will affect the bonding effect with the workpiece and cause problems such as misalignment and deformation of the transfer pattern. The transfer film of the present invention can maintain dimensional stability at high temperatures, ensuring that the transfer pattern can be accurately and completely transferred to the workpiece surface, effectively improving the quality and consistency of the transfer product.

[0104] In summary, the thermal transfer film of this invention demonstrates excellent performance in both hot stretch and warpage, significantly outperforming conventional polyolefin-based materials and other thermal transfer films. Its exceptional high-temperature hot stretch and dimensional stability offer broad application prospects in the thermal transfer field, enabling it to meet the demands of transfer printing in a variety of complex working conditions and providing a strong foundation for improving transfer product quality and production efficiency.

Claims

1. A transfer film structure, characterized in that: The transfer film is a two-layer co-extruded structure, comprising: a first textured layer (11), wherein one surface of the first textured layer (11) has textures; A first bright surface layer (12), wherein the first bright surface layer (12) is arranged on a side of the first texture layer (11) that does not have textures.

2. A transfer film structure according to claim 1, characterized in that: The first texture layer (11) is prepared from the following components in parts by weight: 60-80 parts of copolymerized polypropylene, 10-20 parts of EPDM elastomer, and 5-10 parts of spherical silica lubricating masterbatch.

3. The transfer film structure according to claim 1, characterized in that: The first bright surface layer (12) is prepared from the following components in parts by weight: 70-90 parts of copolymerized polypropylene, 5-15 parts of EPDM elastomer, and 10-20 parts of polyethylene.

4. A transfer film structure, characterized in that: The transfer film is a three-layer co-extruded structure, comprising: a second textured layer (13), wherein one surface of the second textured layer (13) has textures; a second bright surface layer (14), the second bright surface layer (14) being arranged on a side of the second textured layer (13) that does not have textures; An intermediate layer (15), wherein the intermediate layer (15) is arranged between the second texture layer (13) and the second bright surface layer (14).

5. The transfer film structure according to claim 4, characterized in that: The second texture layer (13) is prepared from the following components in parts by weight: 50-70 parts of homopolypropylene, 15-25 parts of EPDM elastomer, and 8-12 parts of spherical silica lubricating masterbatch.

6. The transfer film structure according to claim 4, characterized in that: The second bright surface layer (14) is prepared from the following components in parts by weight: 65-85 parts of copolymerized polypropylene and 8-18 parts of EPDM elastomer.

7. The transfer film structure according to claim 4, characterized in that: The intermediate layer (15) is prepared from the following components in parts by weight: 55-75 parts of copolymerized polypropylene, 12-22 parts of EPDM elastomer, and 15-25 parts of polyethylene.

8. A transfer film structure according to any one of claims 1 to 7, characterized in that: The preparation method includes: mixing different polymer particles evenly according to the formula, pouring them into different extruder hoppers respectively, and extruding the melt to the distributor through high-temperature plasticization and shearing by the screw, and then flowing into the extrusion device; after the melt flows out of the extruder, it is thinned and formed by embossing rollers, and then cooled and shaped by air again, and then sent to the winding device after corona treatment to complete the production of the transfer film structure.

9. A method for thermal transfer of a pattern of a transfer film structure, characterized in that: The steps include: S1, coating a release layer (2), a UV texture layer (3), a light-enhancing layer (4), a printing layer (5), and an adhesive layer (6) on the inner side of a transfer film (1) in sequence to obtain a film for thermal transfer; S2. Place the coated film flatly on the workbench of the thermal transfer equipment, and at the same time place the workpiece (7) to be transferred at the corresponding position below the film, start the equipment so that the transfer table enters the mold closing position of the thermal transfer equipment to perform the mold closing operation, ensuring that the positions of the film and the workpiece are accurately aligned to avoid deviation of the transfer pattern; S3. After the mold is closed, start the vacuum system of the thermal transfer equipment to evacuate the upper and lower cavities at the same time until the vacuum degree in the cavity reaches -0.098 MPa. The air in the cavity is removed by vacuuming to prevent the formation of bubbles during the thermal transfer process, which affects the quality of the transfer pattern and ensures the flatness and integrity of the transfer pattern. S4. While maintaining the vacuum degree of the upper and lower cavities at -0.098 MPa, start the heating system of the thermal transfer equipment to heat the film, gradually heating the film to the pre-set transfer temperature. During the heating process, continuously monitor the film temperature to ensure that the temperature rises evenly to avoid local overheating that may damage the film or pattern, or insufficient temperature that may affect the melting and bonding effect of the adhesive layer; S5. When the diaphragm temperature reaches the set temperature, the neutron plate of the thermal transfer equipment slowly lifts the workpiece to be transferred, so that the workpiece and the diaphragm gradually approach and finally fit tightly together; at the same time, high-pressure gas is filled into the upper cavity of the thermal transfer equipment, so that the pressure of the upper cavity reaches 0.2 MPa, while the lower cavity maintains a negative pressure of -0.098 MPa. This pressure difference can make the diaphragm fit better on the surface of the workpiece, especially for some workpieces with complex shapes or uneven surfaces. The pressure difference can ensure that the pattern is completely and accurately transferred to all parts of the workpiece; S6. Enter the pressure holding stage, maintain the upper cavity pressure at 0.2 MPa, and the lower cavity maintains a negative pressure state of -0.098 MPa. During the pressure holding process, the adhesive layer fully melts and penetrates into the microstructure of the workpiece surface, so that the transfer pattern and the workpiece form a strong bond. At the same time, ensure that the UV texture layer, gloss enhancement layer and printing layer are closely combined with the workpiece, ensuring the quality and stability of the transfer pattern; S7. After the pressure holding is completed, the exhaust system of the thermal transfer equipment is started to exhaust the upper and lower cavities at the same time until the pressure of the upper and lower cavities is 0. After the exhaust is completed, the thermal transfer equipment is opened and the workpiece after the transfer is completed is taken out. At this time, the pattern on the transfer film has been successfully transferred to the surface of the workpiece. The transfer film (1) and the release layer (2) are peeled off. The release layer (2) can smoothly separate the transfer film (1) from the pattern to obtain a transfer product with a beautiful pattern.

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