Multilayer structure for out-of-mold transfer printing and preparation method thereof
By preparing a combination of multi-layered functional decorative layer, base layer, support layer and stress buffer layer, the problem of warping and deformation caused by uneven stress in out-of-mold transfer printing was solved, achieving high-quality transfer printing and rich decorative effects for 3C electronic product shells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-04-14
AI Technical Summary
Existing multi-layer structures for external transfer printing suffer from uneven stress and warping during the transfer process, or insufficient stretching when the surface structure of the laminate is complex, resulting in deformation or distorted effects.
A functional decorative layer is prepared by using thermoplastic plastic particles through a casting machine, and a primer is applied to the smooth surface to form a base layer. An organosilicon pressure-sensitive adhesive is coated on the support layer to form a first adhesive layer. The frosted surface is then laminated with the first adhesive layer, and a stress buffer layer is laminated on the side of the support layer away from the first adhesive layer to form a multi-layer structure.
It improves the mechanical strength and dimensional stability of the multi-layer structure, prevents curling and deformation during multiple baking processes in the out-of-mold transfer printing process, and ensures that the outer layer is clearly and completely transferred to the casing of 3C electronic products, providing a deep texture and dynamic color effect.
Smart Images
Figure CN121848847A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of surface treatment technology for 3C electronic products, and in particular to a multilayer structure for out-of-mold transfer printing and its preparation method. Background Technology
[0002] Currently, the surface decoration of 3C electronic product casings mainly adopts processes such as spraying, stenciling, or water transfer printing. These traditional processes generally have drawbacks such as significant environmental pollution, monotonous visual effects, and poor wear resistance. As consumers' demands for personalized appearance and texture of electronic products increase, the market urgently needs a new surface treatment solution that can achieve complex micro-nano textures, diverse color effects, and is environmentally friendly.
[0003] Out-of-mold transfer (OMR) technology is an emerging surface decoration process that can transfer complex patterns and effects pre-formed on a thin film onto the surface of a workpiece in a single step. However, existing transfer film materials (PET-like materials) still have shortcomings in terms of structural stability, multi-layered transfer effects, and adaptability to complex processes. For example, during multiple baking processes, the material is prone to warping due to uneven stress, or insufficient stretching when the surface of the laminate is complex, leading to deformation or distortion of the effect. Therefore, developing a composite film material that is structurally stable, widely applicable, and capable of supporting rich decorative effects is of great significance. Summary of the Invention The main objective of this invention is to provide a multilayer structure for off-mold transfer and its preparation method, aiming to solve the technical problems of uneven stress and warping during the transfer process of existing multilayer structures for off-mold transfer, or insufficient stretching when the surface structure of the laminate is complex, resulting in deformation or distortion of the effect.
[0004] To achieve the above objectives, the present invention provides a method for preparing a multilayer structure for off-mold transfer printing, the method comprising: Thermoplastic particles are used as raw materials, melted and extruded in a casting machine, and then cooled and shaped to form a functional decorative layer. The front side of the functional decorative layer is calendered with mirror rollers of the casting machine to form a smooth surface, and the back side of the functional decorative layer is calendered with frosted rollers of the casting machine to form a frosted surface. A primer is applied to the smooth surface and baked to cure, forming a base coating layer; A support layer is provided, and an organosilicon pressure-sensitive adhesive is coated on the support layer and baked to activate it, forming a first adhesive layer; The first adhesive layer is bonded to the frosted surface; A stress buffer layer is composited on the side of the support layer away from the first adhesive layer to form a multi-layer structure.
[0005] Furthermore, in one embodiment, after the step of applying a primer to the smooth surface and baking it to cure, forming a base coating, the method further includes: A peelable protective layer is applied to the side of the base coating away from the functional decorative layer.
[0006] Further, in one embodiment, the step of forming a multilayer structure by merging a stress buffer layer on the side of the support layer away from the first adhesive layer includes: A stress buffer layer is provided, and a liquid adhesive is coated on one side of the stress buffer layer to form a second adhesive layer, wherein the liquid adhesive is acrylic adhesive; The side of the second adhesive layer away from the stress buffer layer is bonded to the side of the support layer away from the first adhesive layer.
[0007] Further, in one embodiment, the step of forming a multilayer structure by merging a stress buffer layer on the side of the support layer away from the first adhesive layer includes: On the side of the support layer away from the first adhesive layer, the stress buffer layer coated with acrylate pressure-sensitive adhesive is laminated by hot pressing process to form a multilayer structure.
[0008] Further, in one embodiment, the step of applying a primer to the smooth surface and baking it to cure, forming a base coating layer, includes: A primer is applied to the smooth surface using a gravure coating method and then cured by heating and baking. The heating and baking temperature is 90℃-100℃ and the heating and baking time is 8 minutes-12 minutes.
[0009] Further, in one embodiment, the step of bonding the first adhesive layer to the frosted surface includes: The first adhesive layer is bonded to the frosted surface using a hot-pressing process.
[0010] Furthermore, in one embodiment, the material of the functional decorative layer is a polyolefin thermoplastic; and / or, The support layer is a polyethylene terephthalate film with a thickness of 0.188 mm to 0.25 mm.
[0011] Further, in one embodiment, the stress buffer layer is a polypropylene film with a thickness of 0.05 mm to 0.075 mm; and / or, The primer is made of polyurethane.
[0012] The present invention also provides a multilayer structure for out-of-mold transfer printing, wherein the multilayer structure is fabricated using the aforementioned preparation method, and the multilayer structure comprises: A functional decorative layer having a frosted surface and a smooth surface; A base coating layer is disposed on the smooth surface; Support layer; A first adhesive layer, one side of which is disposed on the support layer, and the other side of which is disposed on the frosted surface; A stress buffer layer is disposed on the side of the support layer away from the functional decorative layer.
[0013] Furthermore, in one embodiment, the multilayer structure further includes a protective layer disposed on the side of the base layer away from the functional decorative layer; and / or, The multilayer structure further includes a second adhesive layer disposed between the support layer and the stress buffer layer.
[0014] In the technical solution provided by this invention, thermoplastic particles are used as raw materials. After being melted and extruded in a casting machine, a functional decorative layer with a smooth surface and a frosted surface is prepared through a cooling and shaping process. A primer is applied to the smooth surface and baked to form a base layer. The base layer increases the adhesion of the subsequent appearance layer. A support layer is prepared in advance. An organosilicon-sensitive adhesive is applied to the support layer and baked to activate it, forming a first adhesive layer. The frosted surface of the functional decorative layer is then covered on the first adhesive layer. Pressure is applied to firmly press the functional decorative layer onto the first adhesive layer, so that the support layer and the functional decorative layer are firmly bonded. This allows the support layer to provide mechanical strength and dimensional stability for the entire multi-layer structure. A stress buffer layer is composited on the surface of the support layer away from the first adhesive layer to form a multi-layer structure. Because the material of the stress buffer layer shrinks when heated, the multi-layer structure is used to offset internal stress during the multiple baking processes of the out-of-mold transfer printing process, preventing curling and deformation. This ensures that the appearance layer located on the multi-layer structure is clearly and completely transferred to the 3C electronic product casing, thereby giving the 3C electronic product casing a deep texture and dynamic color effect. Attached Figure Description
[0015] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.
[0016] Figure 1 This is a schematic diagram of the first embodiment of the method for preparing a multilayer structure for off-mold transfer printing according to the present invention; Figure 2 This is a schematic diagram of a second embodiment of the method for preparing a multilayer structure for off-mold transfer in this invention. Figure 3This is a schematic diagram of a third embodiment of the method for preparing a multilayer structure for off-mold transfer in this invention. Figure 4 This is a schematic diagram of a multi-layer structure for off-mold transfer printing in an embodiment of the present invention; Figure 5 This is a schematic diagram of a multi-layer structure for out-of-mold transfer printing in an embodiment of the present invention, in which a protective layer is covered on the base coating.
[0017] Among them, 100 is a multi-layer structure; 10 is a functional decorative layer; 60 is a base coating layer; 20 is a support layer; 30 is a first adhesive layer; 40 is a second adhesive layer; 50 is a stress buffer layer; and 70 is a protective layer. Detailed Implementation
[0018] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and similar expressions used in this specification are for illustrative purposes only. In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of indicated technical features. Thus, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.
[0019] Furthermore, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections via an intermediate medium, or internal communication between two components. All technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.
[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0021] For ease of understanding, the specific process of the embodiments of the present invention is described below. Please refer to [link / reference]. Figure 1 The first embodiment of a method for preparing a multilayer structure for off-mold transfer printing according to the present invention includes: S1. Thermoplastic particles are used as raw materials, melted and extruded in a casting machine, and then cooled and shaped to form a functional decorative layer; wherein, the front side of the functional decorative layer is calendered by the mirror roller of the casting machine to form a smooth surface, and the back side of the functional decorative layer is calendered by the frosted roller of the casting machine to form a frosted surface. In this step, the material of the functional decorative layer is a polyolefin thermoplastic. Therefore, the thermoplastic particles can be polyolefin thermoplastic particles. Furthermore, the polyolefin thermoplastic particles are at least one or more of polyethylene, polypropylene, or EVA copolymers. After pretreatment in the drying tower of the casting machine, the raw materials are melted and plasticized in a temperature field of 190-230℃ using a precision single-screw extruder. The melt is filtered through a stainless steel screen and then enters a flat die head (die gap adjustable from 0.5-2.0mm) to form a melt curtain of uniform thickness. After entering the casting system, the front side contacts a mirror-finish roller to form a smooth surface, and the back side contacts a frosted roller to form a frosted surface. Then, a three-stage gradient cooling system is used: a rapid cooling roller (surface temperature 30-50℃) quickly solidifies the surface layer, a slow cooling roller (surface temperature 60-80℃) eliminates internal stress, and the final shaping is completed in a natural cooling zone (room temperature).
[0022] Among them, after the functional decorative layer is formed and rolled up, the frosted surface is less likely to stick together and cause bubbling marks compared to the smooth surface.
[0023] S2. Apply a primer to the smooth surface and bake it to cure, forming a base coating layer; In this step, the primer can be polyurethane. After uniformly applying a layer of polyurethane primer to the smooth surface of the functional decorative layer, the primer is baked and cured to form a base layer. This improves the surface dyne value of the functional decorative layer, preventing the low surface energy of the functional decorative layer from failing to effectively bond with the process resin and causing delamination after processing. This ensures the adhesion of subsequent appearance layers (such as inks and coatings).
[0024] The coating thickness of the primer can be 2µm.
[0025] S3. Provide a support layer, coat the support layer with silicone pressure-sensitive adhesive and bake to activate it, forming a first adhesive layer; In this step, the support layer is a polyethylene terephthalate film with a thickness of 0.188mm-0.25mm. A polyethylene terephthalate film with a thickness of 0.188mm or 0.25mm is selected, and a uniform layer of silicone pressure-sensitive adhesive is coated on the film. The film is then baked at a temperature of 160-170℃ for 2-3 minutes to activate it, forming the first adhesive layer, which can then be adhered to the support layer.
[0026] S4. Composite the first adhesive layer with the frosted surface; In this step, the frosted surface of the functional decorative layer is bonded to the activated first adhesive layer, and the functional decorative layer and the first adhesive layer are firmly bonded together through a hot-pressing process, thus combining the support layer and the functional decorative layer. The support layer provides mechanical strength and dimensional stability to the entire multilayer structure.
[0027] S5. A stress buffer layer is composited on the side of the support layer away from the first adhesive layer to form a multi-layer structure.
[0028] In this step, the stress buffer layer is made of polypropylene film with a thickness of 0.05mm-0.075mm. A 0.05mm thick polypropylene film is bonded to the surface of the support layer away from the first adhesive layer using a hot-pressing process. Since the polypropylene film shrinks when heated, it is used to offset internal stress during the multiple baking processes of the external transfer printing process, prevent curling and deformation, and ensure that the appearance layer located on the multi-layer structure is clearly and completely transferred to the 3C electronic product casing. This gives the 3C electronic product casing a deep texture and dynamic color effect, while also making the multi-layer structure widely applicable.
[0029] In this embodiment, thermoplastic particles are used as raw materials. After being melted and extruded in a casting machine, a functional decorative layer with a smooth and frosted surface is prepared through a cooling and shaping process. A primer is applied to the smooth surface and baked to form a base layer. The base layer increases the adhesion of the subsequent appearance layer. A support layer is prepared in advance. An organosilicon-sensitive adhesive is applied to the support layer and baked to activate it, forming a first adhesive layer. The frosted surface of the functional decorative layer is then placed on the first adhesive layer. Pressure is applied to firmly press the functional decorative layer onto the first adhesive layer, so that the support layer and the functional decorative layer are firmly bonded together. This allows the support layer to provide mechanical strength and dimensional stability for the entire multilayer structure. A stress buffer layer is composited on the surface of the support layer away from the first adhesive layer to form a multilayer structure. Because the material of the stress buffer layer shrinks when heated, the multilayer structure is used to offset internal stress during the multiple baking processes of the out-of-mold transfer printing process, preventing curling and deformation. This ensures that the appearance layer located on the multilayer structure is clearly and completely transferred to the 3C electronic product casing, thereby giving the 3C electronic product casing a deep texture and dynamic color effect, while also making the multilayer structure widely applicable.
[0030] Please see Figure 2 As shown in the figure, a second embodiment of a method for manufacturing a 3D solid structure is also disclosed in this invention. The second embodiment includes: S11. Thermoplastic particles are used as raw materials, melted and extruded in a casting machine, and then cooled and shaped to form a functional decorative layer; wherein, the front side of the functional decorative layer is calendered by the mirror roller of the casting machine to form a smooth surface, and the back side of the functional decorative layer is calendered by the frosted roller of the casting machine to form a frosted surface. In this step, the description of step S11 refers to S1 of the first embodiment, and will not be repeated in this embodiment.
[0031] S12. Apply a base coat to the smooth surface by gravure coating and heat and bake to cure. The heating and baking temperature is 90℃-100℃ and the heating and baking time is 8 minutes-12 minutes. In this step, the primer can be polyurethane-based, and the heating and baking time is 8-12 minutes. Specifically, after uniformly applying a layer of polyurethane-based primer to the smooth surface of the functional decorative layer using a three-roll gravure coating machine, the applied primer is baked at 90-100℃ for 8 minutes, 10 minutes, or 12 minutes to cure it, forming a base layer. This improves the surface dynamism value of the functional decorative layer, preventing the low surface energy of the functional decorative layer from failing to effectively bond with the process resin, which would result in delamination after processing. This ensures the adhesion of subsequent appearance layers, such as inks or coatings.
[0032] The coating thickness of the primer can be 2µm.
[0033] S13. Cover the side of the base coating away from the functional decorative layer with a peelable protective layer; In this step, immediately at the coating machine exit, a layer of polyolefin self-adhesive film is applied to the uncooled base coat. That is, a peelable polyolefin self-adhesive film is applied to the surface of the base coat that is far away from the functional decorative layer. This serves as a protective layer for the process and can be peeled off before the subsequent off-mold transfer process. It is used to protect the base coat surface from contamination and damage during production and transportation.
[0034] S14. Provide a support layer, coat the support layer with silicone pressure-sensitive adhesive and bake to activate it, forming a first adhesive layer; In this step, the description of step S14 refers to S3 of the first embodiment, and will not be repeated in this embodiment.
[0035] S15. The first adhesive layer is bonded to the frosted surface by hot pressing. In this step, the frosted surface of the functional decorative layer is covered on the activated first adhesive layer, and then a hot-pressing process is used to firmly adhere the functional decorative layer to the first adhesive layer, thereby ensuring that the support layer is firmly set on the functional decorative layer. The support layer provides mechanical strength and dimensional stability for the entire multi-layer structure.
[0036] S16. Provide a stress buffer layer, and coat one side of the stress buffer layer with a layer of liquid adhesive to form a second adhesive layer, wherein the liquid adhesive is acrylic adhesive; In this step, the stress buffer layer is made of polypropylene film with a thickness of 0.05mm-0.075mm. The liquid adhesive can be acrylic adhesive, UV adhesive, or silicone adhesive. Preferably, the liquid adhesive is acrylic adhesive, which has good bonding effect and low cost. The stress buffer layer can be a polypropylene film with a thickness of 0.05mm-0.075mm. A layer of liquid acrylic adhesive is coated on one surface of the polypropylene film to form a second adhesive layer.
[0037] S17. The side of the second adhesive layer away from the stress buffer layer is bonded to the side of the support layer away from the first adhesive layer.
[0038] In this step, the surface of the support layer away from the first adhesive layer is covered over the side of the second adhesive layer away from the stress buffer layer. The support layer is then firmly bonded to the second adhesive layer using a hot-pressing process, thereby ensuring that the stress buffer layer is firmly bonded to the support layer, resulting in a multi-layer structure. Because the polypropylene film shrinks when heated, it is used to offset internal stress during the multiple baking processes of the out-of-mold transfer printing process, preventing curling and deformation, and ensuring that the appearance layer located on the multi-layer structure is clearly and completely transferred to the 3C electronic product casing, thus giving the 3C electronic product casing a deep texture and dynamic color effect.
[0039] In this embodiment, thermoplastic particles are used as raw materials. After being melt-extruded in a casting machine, a functional decorative layer with a smooth and frosted surface is prepared through a cooling and shaping process. A primer is applied to the smooth surface and baked to form a base layer. The base layer increases the adhesion of the subsequent appearance layer, and a protective layer is covered on the base layer to prevent it from being scratched or contaminated in subsequent processes. A support layer is prepared in advance, and an organosilicon-sensitive adhesive is applied to the support layer and baked to activate it, forming a first adhesive layer. The frosted surface of the functional decorative layer is then placed on the first adhesive layer, and pressure is applied to firmly press the functional decorative layer onto the first adhesive layer, so that the support layer and the functional decorative layer are firmly bonded together, thereby enabling the support layer to form a functional decorative layer. The support layer provides mechanical strength and dimensional stability to the entire multi-layer structure. A stress buffer layer is prepared in advance, and a layer of liquid adhesive is applied to the stress buffer layer. Then, the support layer is placed on the surface of the first adhesive layer and covered with the liquid adhesive. The support layer is then firmly bonded to the stress buffer layer through a hot-pressing process to create a multi-layer structure. Because the material of the stress buffer layer shrinks when heated, the multi-layer structure is used to offset internal stress during the multiple baking processes of the out-of-mold transfer printing process, preventing curling and deformation. This ensures that the appearance layer located on the multi-layer structure is clearly and completely transferred to the 3C electronic product casing, thereby giving the 3C electronic product casing a deep texture and dynamic color effect, while also making the multi-layer structure widely applicable.
[0040] Please see Figure 3 As shown, a third embodiment of a method for manufacturing a 3D solid structure is also disclosed in this invention. The third embodiment includes: S21. Thermoplastic particles are used as raw materials, melted and extruded in a casting machine, and then cooled and shaped to form a functional decorative layer; wherein, the front side of the functional decorative layer is calendered by the mirror roller of the casting machine to form a smooth surface, and the back side of the functional decorative layer is calendered by the frosted roller of the casting machine to form a frosted surface. In this step, the description of step S21 refers to S1 of the first embodiment, and will not be repeated in this embodiment.
[0041] S22. Apply a base coat to the smooth surface by gravure coating and heat and bake to cure. The heating and baking temperature is 90℃-100℃ and the heating and baking time is 8 minutes-12 minutes. In this step, the description of step S22 refers to S12 of the second embodiment, and will not be repeated in this embodiment.
[0042] S23. Cover the side of the base coating away from the functional decorative layer with a peelable protective layer; In this step, the description of step S23 refers to S13 of the second embodiment, and will not be repeated in this embodiment.
[0043] S24. Provide a support layer, coat the support layer with silicone pressure-sensitive adhesive and bake to activate it, forming a first adhesive layer; In this step, the description of step S24 refers to S3 of the first embodiment, and will not be repeated in this embodiment.
[0044] S25. The first adhesive layer is bonded to the frosted surface by hot pressing. In this step, the description of step S25 refers to S15 of the first embodiment, and will not be repeated in this embodiment.
[0045] S26. On the side of the support layer away from the first adhesive layer, the stress buffer layer coated with acrylate pressure-sensitive adhesive is laminated by hot pressing process to form a multilayer structure.
[0046] In this step, the stress buffer layer can be a polypropylene film with a thickness of 0.05mm-0.075mm. A polypropylene film with its own acrylate pressure-sensitive adhesive is provided. The adhesive side of the polypropylene film with its own acrylate pressure-sensitive adhesive is placed on the surface of the support layer away from the first adhesive layer. Then, a hot-pressing process is used to firmly bond the stress buffer layer to the first adhesive layer, resulting in a multi-layer structure. Because the polypropylene film shrinks when heated, it is used to offset internal stress during the multiple baking processes of the out-of-mold transfer printing process, preventing curling and deformation. This ensures that the appearance layer located on the multi-layer structure is clearly and completely transferred to the 3C electronic product casing, thereby giving the 3C electronic product casing a deep texture and dynamic color effect.
[0047] In this embodiment, thermoplastic particles are used as raw materials. After being melt-extruded in a casting machine, a functional decorative layer with a smooth and frosted surface is prepared through a cooling and shaping process. A primer is applied to the smooth surface and baked to form a base layer. The base layer increases the adhesion of the subsequent appearance layer, and a protective layer is covered on the base layer to prevent it from being scratched or contaminated in subsequent processes. A support layer is prepared in advance, and an organosilicon-sensitive adhesive is applied to the support layer and baked to activate it, forming a first adhesive layer. The frosted surface of the functional decorative layer is then placed on the first adhesive layer, and pressure is applied to firmly press the functional decorative layer onto the first adhesive layer, so that the support layer and the functional decorative layer are firmly bonded together, thereby achieving the desired effect. The support layer provides mechanical strength and dimensional stability to the entire multilayer structure. The adhesive side of a polypropylene film with its own acrylate pressure-sensitive adhesive is covered on the surface of the support layer away from the first adhesive layer. Then, a hot-pressing process is used to press the film together, so that the stress buffer layer is firmly attached to the first adhesive layer, resulting in a multilayer structure. Because the material of the stress buffer layer shrinks when heated, the multilayer structure is used to offset internal stress during the multiple baking processes of the out-of-mold transfer printing process, preventing curling and deformation. This ensures that the appearance layer located on the multilayer structure is clearly and completely transferred to the 3C electronic product casing, thereby giving the 3C electronic product casing a deep texture and dynamic color effect, while also making the multilayer structure widely applicable.
[0048] This invention also discloses the preparation of a multilayer structure for external transfer printing of a mobile phone battery cover mold. Specifically, this embodiment is as follows: Step 1: Select polyethylene particles, melt and extrude them at 180-220℃ using a casting machine, cool and shape them using a combination of mirror rollers and frosted rollers, and then roll them up to obtain a polyolefin base film master roll with a width of 1.08 meters and a length of 2000 meters. The front of the base film is smooth and the back has a frosted texture.
[0049] Step 2: Apply a 2µm thick polyurethane primer evenly to the smooth surface of the polyolefin-based film using a gravure coating method, and then bake it in a 100°C oven for 10 minutes to increase the surface dyne value to above 34.
[0050] Step 3: Immediately at the coating machine exit, apply a layer of polyolefin self-adhesive film to the uncooled base coating as a process protection layer to prevent scratches and contamination in subsequent processes, and then rewind.
[0051] Step 4: Take a transparent polyethylene terephthalate plastic film with a thickness of 0.188mm or 0.25mm, coat one side with silicone pressure-sensitive adhesive, bake it in a 160℃ oven for 2 minutes to activate the adhesive properties, and then firmly bond it to the frosted surface of the polyolefin base film through a hot press roller, and then roll it up.
[0052] Step 5: On the terephthalic acid plastic surface of the laminated roll material, heat-laminate a layer of adhesive polypropylene film with a thickness of 0.05mm.
[0053] Step 6: The final multi-layer composite roll is slit into finished rolls of 330mm x 200mm width using a slitting machine, for use in subsequent external transfer printing decoration processing.
[0054] Step 7: After peeling off the protective layer of the multi-layer structure, the surface of the base coating layer is sequentially subjected to UV micro-texture embossing, vacuum coating, color printing and other appearance layers. Then, the appearance layers on the multi-layer structure are transferred to the mobile phone battery case through an off-mold transfer process to produce a mobile phone battery cover with a deep texture and dynamic color effect.
[0055] The following table shows the test results for the exterior layer of the mobile phone battery cover, which exhibits a deep texture and dynamic color effects:
[0056] like Figure 4 As shown, this embodiment of the invention also discloses a multi-layer structure for off-mold transfer printing. The multi-layer structure is manufactured by the manufacturing method of any of the above embodiments, and the manufacturing method of any of the above embodiments can produce a multi-layer structure.
[0057] The multi-layer structure 100 includes a functional decorative layer 10, a base coating layer 60, a support layer 20, a first adhesive layer 30, and a stress buffer layer 50. The functional decorative layer 10 has a frosted surface and a smooth surface; the base coating layer 60 is disposed on the smooth surface; the support layer 20; one side of the first adhesive layer 30 is disposed on the support layer 20, and the other side of the first adhesive layer is disposed on the frosted surface; the stress buffer layer is disposed on the side of the support layer 20 away from the functional decorative layer 10; the multi-layer structure 100 also includes a second adhesive layer 40, which is disposed between the support layer 20 and the stress buffer layer. This multi-layer structure 100 achieves uniform stress distribution and improves elasticity and ductility, ensuring a clear and complete transfer effect in the subsequent process, while also making the multi-layer structure widely applicable.
[0058] like Figure 5 As shown, Figure 5 In another embodiment of the multilayer structure 100, which is covered by a protective layer 70, the multilayer structure 100 further includes a protective layer 70 disposed on the side of the base coating 60 away from the functional decorative layer 10. The protective layer 70 is used to protect the base coating 60 and prevent the base coating 60 from being scratched and contaminated during production or transportation.
[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a multilayer structure for off-mold transfer printing, characterized in that, The preparation method includes: Thermoplastic particles are used as raw materials, melted and extruded in a casting machine, and then cooled and shaped to form a functional decorative layer. The front side of the functional decorative layer is calendered with mirror rollers of the casting machine to form a smooth surface, and the back side of the functional decorative layer is calendered with frosted rollers of the casting machine to form a frosted surface. A primer is applied to the smooth surface and baked to cure, forming a base coating layer; A support layer is provided, and an organosilicon pressure-sensitive adhesive is coated on the support layer and baked to activate it, forming a first adhesive layer; The first adhesive layer is bonded to the frosted surface; A stress buffer layer is composited on the side of the support layer away from the first adhesive layer to form a multi-layer structure.
2. The preparation method according to claim 1, characterized in that, After the step of applying a primer to the smooth surface and baking it to form a base coating, the method further includes: A peelable protective layer is applied to the side of the base coating away from the functional decorative layer.
3. The preparation method according to claim 1, characterized in that, The step of forming a multi-layer structure by adding a stress buffer layer to the side of the support layer away from the first adhesive layer includes: A stress buffer layer is provided, and a liquid adhesive is coated on one side of the stress buffer layer to form a second adhesive layer, wherein the liquid adhesive is acrylic adhesive; The side of the second adhesive layer away from the stress buffer layer is bonded to the side of the support layer away from the first adhesive layer.
4. The preparation method according to claim 1, characterized in that, The step of forming a multi-layer structure by adding a stress buffer layer to the side of the support layer away from the first adhesive layer includes: On the side of the support layer away from the first adhesive layer, the stress buffer layer coated with acrylate pressure-sensitive adhesive is laminated by hot pressing process to form a multilayer structure.
5. The preparation method according to claim 1, characterized in that, The step of applying a primer to the smooth surface and baking it to cure, forming a base coating layer, includes: A primer is applied to the smooth surface using a gravure coating method and then cured by heating and baking. The heating and baking temperature is 90℃-100℃ and the heating and baking time is 8 minutes-12 minutes.
6. The preparation method according to claim 1, characterized in that, The step of bonding the first adhesive layer to the frosted surface includes: The first adhesive layer is bonded to the frosted surface using a hot-pressing process.
7. The preparation method according to claim 1, characterized in that, The functional decorative layer is made of polyolefin thermoplastic; and / or, The support layer is a polyethylene terephthalate film with a thickness of 0.188 mm to 0.25 mm.
8. The preparation method according to claim 1, characterized in that, The stress buffer layer is a polypropylene film with a thickness of 0.05mm-0.075mm; and / or, The primer is made of polyurethane.
9. A multi-layer structure for off-mold transfer printing, characterized in that, The multilayer structure is prepared by the preparation method according to any one of claims 1 to 8, and the multilayer structure comprises: A functional decorative layer having a frosted surface and a smooth surface; A base coating layer is disposed on the smooth surface; Support layer; A first adhesive layer, one side of which is disposed on the support layer, and the other side of which is disposed on the frosted surface; A stress buffer layer is disposed on the side of the support layer away from the functional decorative layer.
10. The multilayer structure according to claim 9, characterized in that, The multilayer structure further includes a protective layer disposed on the side of the base coating layer away from the functional decorative layer; and / or, The multilayer structure further includes a second adhesive layer disposed between the support layer and the stress buffer layer.