Gold stamping film with double-sided differentiated metal effect and preparation process of gold stamping film

Abstract

The invention discloses a gold stamping film with a double-sided differentiated metal effect, which belongs to the technical field of packaging materials and comprises a release layer, a first metal layer, a base film, a second metal layer and an adhesive layer which are stacked in the thickness direction. The first metal layer is a mirror surface metal layer, and the second metal layer is a matte metal layer; or the first metal layer and the second metal layer are mirror surface metal layers with different effects; the glossiness of the first metal layer is greater than that of the second metal layer. The invention further discloses a preparation method of the gold stamping film. The metal layers with different visual effects are formed on the two surfaces of the single base film through different processing technologies, and the double-sided effect is synchronously transferred through one-time hot stamping, so that the problems of low efficiency, difficulty in registration, large thickness, easiness in layering and the like existing in a'two-layer base film compounding 'or'single-sided multi-layer stacking' structure in the prior art are solved.

Description

Technical Field

[0001] This invention belongs to the field of packaging materials technology, specifically relating to a hot stamping film with double-sided differentiated metallic effects and its preparation process. Background Technology

[0002] To achieve a metallic effect on tobacco and alcohol packaging, luxury brand tags, high-end notebooks, and the edges of electronic products, while also giving them a double-sided metallic texture, traditional technical solutions generally use single-sided hot stamping film or composite double-sided film.

[0003] For single-sided hot stamping film, hot stamping is required on both sides of the substrate to achieve a double-sided silver effect. The entire process is complex and requires high skill in hot stamping techniques. Alignment of the two stamping positions is crucial, increasing the risk of misalignment due to registration errors. Furthermore, controlling the temperature difference between the two stamping processes is essential to prevent dust accumulation on the end faces of both stamping processes.

[0004] Composite double-sided film is produced by bonding two aluminum-plated base films (A and B) together using an adhesive coating process to create a double-sided mirror effect. However, after hot stamping, there is a high risk of delamination between the base films A and B. This necessitates strict control over interlayer peel force and the storage environment of the hot-stamped item, increasing the performance requirements of the adhesive layer. Furthermore, after the composite double-sided film is applied to the sample, stress concentration can easily occur at the composite interface over time, making the edges of the composite base film prone to delamination and edge warping. Additionally, the adhesive coating between the two base films reduces the light transmittance and uniformity of light transmission, resulting in a higher surface haze and a poorer decorative effect. Summary of the Invention

[0005] In response to one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides a hot stamping film with double-sided differentiated metallic effects. Different processing techniques are used to form metallic layers with different visual effects on the two surfaces of a single base film, and the double-sided effects are transferred simultaneously in one hot stamping process.

[0006] To achieve the above objectives, according to one aspect of the present invention, a hot stamping film with double-sided differentiated metallic effects is provided, comprising a release layer, a first metal layer, a base film, a second metal layer and an adhesive layer stacked in the thickness direction; The first metal layer is a mirror metal layer, and the second metal layer is a matte metal layer; or the first metal layer and the second metal layer are mirror metal layers with different effects. The gloss of the first metal layer is greater than that of the second metal layer.

[0007] As a further improvement of the present invention, when the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer, the surface gloss of the first metal layer is greater than 95 GU and the surface gloss of the second metal layer is less than 30 GU.

[0008] As a further improvement of the present invention, the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; The first metal layer is deposited on one side of the base film by magnetron sputtering, and the second metal layer is deposited by vacuum evaporation after imprinting a texture onto the other side of the base film; or... Both the first and second metal layers are deposited using magnetron sputtering; the second metal layer reduces gloss by reacting with lower power, higher gas pressure, higher base film temperature, or by introducing oxygen or nitrogen compared to the first metal layer; or... Both the first metal layer and the second metal layer are deposited by vacuum evaporation. Before vacuum evaporation, the first metal layer is coated with a smooth base oil, and before vacuum evaporation, the second metal layer is coated with a base oil containing matting powder, or a texture is formed by embossing.

[0009] As a further improvement of the present invention, the first metal layer and the second metal layer are mirror metal layers with differentiated effects; The first metal layer was deposited by magnetron sputtering, and the second metal layer was deposited by vacuum evaporation. Alternatively, the first metal layer and the second metal layer may be deposited using different metals via magnetron sputtering or vacuum evaporation. Alternatively, the first metal layer may be deposited by magnetron sputtering, and the second metal layer may be formed by chemical coloring and chemical etching based on magnetron sputtering.

[0010] As a further improvement of the present invention, the release layer is a thermally decomposable protective layer, and its material is an acrylic resin solution containing 0.3% to 0.5% thermally decomposable foaming agent.

[0011] As a further improvement of the present invention, the material of the thermally decomposable protective layer includes 100 parts of resin matrix, 1-20 parts of foaming agent, 0.3-10 parts of activator, 0.2-10 parts of crosslinking aid, 0-100 parts of inorganic filler, 10-50 parts of pigment; and 200-400 parts of solvent. Preferably, the resin matrix comprises one or more of ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer; the foaming agent is azodicarbonamide; the activator comprises one or more of zinc oxide and zinc stearate; the crosslinking aid is trimethylolpropane triacrylate; the inorganic filler comprises one or more of calcium carbonate and aluminum hydroxide; the pigment is titanium dioxide; and the solvent is one or more of toluene and ethyl acetate.

[0012] According to another aspect of the present invention, a process for preparing a hot stamping film with double-sided differentiated metallic effects is provided, comprising the following steps: Base film pretreatment: both sides of the base film are subjected to corona or plasma cleaning; A first metal layer and a second metal layer are deposited on both sides of the base film, respectively; the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; or the first metal layer and the second metal layer are mirror metal layers with different effects; the gloss of the first metal layer is greater than the gloss of the second metal layer. Applying release layer: Applying release layer coating to the first metal layer and drying; Apply adhesive layer: Apply adhesive material to the second metal layer and dry.

[0013] As a further improvement of the present invention, the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; A first metal layer is formed on one side of the base film by magnetron sputtering; a texture is first formed on the other side of the base film by nanoimprinting, and then a second metal layer is formed by vacuum evaporation. Alternatively, a first metal layer is formed on one side of the base film by magnetron sputtering; and a second metal layer is formed on the other side of the base film by reacting with lower power, higher gas pressure, higher base film temperature, or by introducing oxygen or nitrogen gas to reduce gloss. Alternatively, a smooth base oil can be applied to one side of the base film before vacuum evaporation to form the first metal layer. On the other side of the base film, a base oil containing matting powder can be applied or a texture can be formed by embossing before vacuum evaporation to form the second metal layer. As a further improvement of the present invention, the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; A first metal layer is formed on one side of the base film by magnetron sputtering or vacuum aluminizing; a second metal layer is formed on the other side of the base film by magnetron sputtering or vacuum aluminizing, and a matte effect is achieved by chemical etching, laser engraving or coating matting.

[0014] As a further improvement of the present invention, the first metal layer and the second metal layer are mirror metal layers with differentiated effects; The first metal layer is formed by magnetron sputtering, and the second metal layer is formed by vacuum evaporation. Alternatively, the first metal layer and the second metal layer can be formed by magnetron sputtering or vacuum evaporation using different metals; Alternatively, the first metal layer can be formed by magnetron sputtering, and the second metal layer can be formed by chemical coloring and chemical etching based on the magnetron sputtering.

[0015] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art: (1) The hot stamping film of the present invention with double-sided differential metallic effect forms a metal layer with different visual effects on the two surfaces of a single base film through different processing technology, and the double-sided effect is transferred simultaneously by hot stamping in one go, avoiding the problems of low efficiency, difficult registration, large thickness and easy delamination of the existing "two-layer base film composite" or "single-sided multi-layer stacking" structure.

[0016] (2) The hot stamping film with double-sided differential metal effect of the present invention forms a mirror metal layer and a matte metal layer in the process of forming a mirror metal layer and a matte metal layer. By cleverly combining two different physical vapor deposition processes (magnetron sputtering and vacuum evaporation) with nanoimprint technology, a double-sided asymmetric optical effect is achieved. The production efficiency is high and the process combination is flexible. The overall film strip presents an integrated ultra-thin structure.

[0017] (3) The hot stamping film of the present invention has a double-sided differentiated metal effect. The mirror metal layer is in direct contact with the release layer, which can enhance the adhesion between the hot stamping film and the release layer. The mirror has a large peeling force before hot stamping and is not easy to fall off, but it is not easy to peel off after hot stamping. The present invention further incorporates a thermal decomposition foaming agent into the release layer, which instantly vaporizes at the hot stamping high temperature, thereby achieving rapid and clean peeling of the protective layer, thus achieving the effect of large cold peeling force and small hot peeling force after hot stamping. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a hot stamping film structure with a double-sided differentiated metallic effect according to an embodiment of the present invention.

[0019] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1, release layer; 2, first metal layer; 3, base film; 4, second metal layer; 5, adhesive layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] As a preferred embodiment of the present invention, the hot stamping film with double-sided differentiated metallic effect of the present invention includes a release layer 1, a first metal layer 2, a base film 3, a second metal layer 4, and an adhesive layer 5.

[0026] The base film, serving as the core support, can be made of biaxially oriented polyester film (BOPET), biaxially oriented polypropylene film (BOPP), polyimide film (PI), or bio-based biodegradable polyester film (such as PLA). Polyimide film (PI) exhibits excellent high-temperature resistance, making it suitable for higher-temperature hot stamping processes or special applications (such as aerospace). Bio-based biodegradable polyester film (such as PLA) offers environmental advantages and aligns with sustainable development trends.

[0027] Preferably, both sides of the base film are subjected to corona or plasma treatment to significantly increase the surface energy (reaching ≥38 dynes / cm), ensuring that the subsequently deposited metal layer has strong adhesion and will not fall off.

[0028] This invention creates differentiated metallic effects on both sides of a base film by setting differentiated metallic layers on both sides, resulting in a differentiated metallic effect on both sides of the substrate (transparent) after final transfer. The differentiated metallic layers are preferably a mirror metallic layer and a matte metallic layer, or a mirror metallic layer with differentiated effects and a mirror metallic layer. More preferably, the first metallic layer on the side of the base film closest to the release layer is a mirror metallic layer, and the second metallic layer on the side of the base film closest to the adhesive layer is a matte metallic layer, or both the first and second metallic layers are mirror metallic layers, with the first metallic layer having a higher gloss than the second metallic layer. The surface of a matte metallic layer is often uneven to create a diffuse matte effect. Therefore, if the matte metallic layer is in direct contact with the release layer, the peel force between them is small, making it easy for the hot stamping film to detach from the release layer. Therefore, this invention enhances the adhesion between the hot stamping film and the release layer by having a mirror metallic layer with higher gloss in direct contact with the release layer.

[0029] Preferably, the surface gloss of the first metal layer (mirror metal layer) is greater than 95 GU, and the surface gloss of the second metal layer (matte metal layer) is less than 30 GU.

[0030] When the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer, the first metal layer and the second metal layer can be formed in the following manner.

[0031] In one embodiment, the first metal layer is deposited by magnetron sputtering, and the second metal layer is deposited by nanoimprinting and vacuum evaporation.

[0032] In this embodiment, for the first metal layer, metal atoms are deposited on one side of the base film using magnetron sputtering to form a dense, smooth, and highly reflective mirror effect. For the second metal layer, a micron-level textured surface (preferably with a surface roughness Ra controlled at 120±20 nm) is first mechanically pressed onto the other side of the base film using nanoimprint lithography. Then, metal is deposited on the textured surface using vacuum evaporation. In a vacuum environment, the metal wire is heated and evaporated, and the metal vapor condenses on the base film surface with low kinetic energy, completely replicating the underlying textured structure, thus creating a matte effect with diffuse light reflection.

[0033] In the second embodiment, double-sided magnetron sputtering is used, that is, both the first metal layer and the second metal layer are deposited by magnetron sputtering.

[0034] In this embodiment, the first metal layer and the second metal layer achieve mirror and matte effects respectively through different process parameters. Specifically, the first metal layer uses a high-power, low-pressure, and low-base-film-temperature process to form a dense, highly reflective coating. The second metal layer uses a lower-power, higher-pressure, and higher-base-film-temperature process, or introduces a small amount of oxygen / nitrogen for reactive sputtering, to form a relatively rough, porous, or chemically compounded coating, thereby reducing gloss.

[0035] For example, the process parameters for magnetron sputtering of the first metal layer are: power 8-15kW, working pressure 0.3-0.8Pa, and base film temperature 25-80℃; the process parameters for magnetron sputtering of the second metal layer are: power 3-8kW, working pressure 1.5-3.0Pa, and base film temperature 60-100℃.

[0036] In the third embodiment, double-sided vacuum evaporation is used, that is, both the first metal layer and the second metal layer are deposited by vacuum evaporation.

[0037] In this embodiment, the first metal layer and the second metal layer achieve mirror and matte effects through different base coatings. The first metal layer is coated with a smooth UV-curable base oil before vacuum evaporation; the second metal layer is coated with a base oil containing matting powder (such as silicon dioxide) before vacuum evaporation, or a textured surface is formed by nanoimprinting before vacuum evaporation.

[0038] In other embodiments, the matte effect of the second metal layer can be achieved after aluminum plating by chemical etching, laser engraving, or a matte coating. Chemical etching involves applying an alkaline solution and locally etching the surface of the metal layer to destroy its mirror-like properties and create matte areas. Laser engraving uses a low-power laser to perform micro-engraving on the surface of the aluminum-plated layer, creating textures that disrupt mirror reflection. A matte coating involves covering the aluminum-plated layer with a transparent protective layer containing a matting agent (such as silica or wax powder), achieving a matte effect through the roughness of the coating itself.

[0039] In addition, the first metal layer and the second metal layer in the embodiments of the present invention can both be made of metals or alloys such as aluminum, copper, chromium, stainless steel or titanium nitride to produce different colored metallic effects (such as gold, copper, gunmetal, etc.). The metal materials of the first metal layer and the second metal layer can be the same or different, and can be selected according to actual needs.

[0040] In a preferred embodiment, the raw material for the adhesive layer can be hot melt adhesive or pressure-sensitive adhesive, etc. When the adhesive layer is a hot melt adhesive, it is obtained by coating a solution or hot melt of polyurethane-type hot melt adhesive onto the second metal layer, and then drying or cooling it in an oven. Its melt index is 8~12 g / 10min, and its melting point is 80~130℃ to ensure rapid melting and firm bonding to the substrate during hot stamping. When the adhesive layer is a pressure-sensitive adhesive, no heating is required during hot stamping; it adheres based on pressure, making it suitable for heat-sensitive substrates.

[0041] In a preferred embodiment, the release layer is a peelable, thermosetting protective layer made of an acrylic resin solution containing 0.3% to 0.5% thermosetting foaming agent (such as azodicarbonamide). It is formed by coating the first metal layer and then curing it in an oven at 80 to 100°C. During hot stamping, the high temperature (approximately 130°C) of the hot stamping machine head causes the foaming agent to vaporize instantly, forming tiny bubbles inside the protective layer. This significantly reduces the adhesion between the release layer and the underlying layer, allowing it to be easily and completely peeled off. If the content of the thermosetting foaming agent is too low, there will be insufficient gas and a strong peeling force; if the content is too high, it may damage the mechanical strength of the release layer, leading to breakage or residue.

[0042] This invention, through improvements in the release layer material, ensures stable and clean peeling of the release layer at a standard hot stamping temperature of 130-150°C, guaranteeing high yield and clear hot stamping edges. Therefore, the mirror metal layer and release layer of this invention achieve a high cold peeling force and low hot peeling force after hot stamping. Furthermore, to ensure uniform diffusion of the gas generated by the foaming agent, it is preferable to form a microstructured surface with certain nanoscale protrusions in the mirror metal layer, while ensuring sufficient mirror gloss and sufficient cold peeling force between the mirror metal layer and the release layer. For example, in embodiments using magnetron sputtering to form the mirror metal layer, high-power pulsed magnetron sputtering can be used, and a trace amount of reactive gas (such as nitrogen or oxygen) can be introduced to form a microstructured surface with certain nanoscale protrusions, which is equivalent to forming a uniform "peeling initiation point" at the interface, reducing the actual contact area and making it easier for the foaming agent gas to spread.

[0043] More preferably, the material of the thermally decomposable protective layer includes 100 parts of resin matrix, 1-20 parts of foaming agent, 0.3-10 parts of activator, 0.2-10 parts of crosslinking aid, 0-100 parts of inorganic filler, 10-50 parts of pigment, and 200-400 parts of solvent; more preferably, the material of the thermally decomposable protective layer includes 100 parts of resin matrix, 3-10 parts of foaming agent, 1-5 parts of activator, 0.5-5 parts of crosslinking aid, 20-70 parts of inorganic filler, 15-30 parts of pigment, and 250-300 parts of solvent.

[0044] More preferably, the resin matrix includes one or more of ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer; the foaming agent is azodicarbonamide; the activator includes one or more of zinc oxide and zinc stearate; the crosslinking aid is trimethylolpropane triacrylate; the inorganic filler includes one or more of calcium carbonate and aluminum hydroxide; the pigment is titanium dioxide; and the solvent is one or more of toluene and ethyl acetate.

[0045] Preferably, the thickness of the release layer 1 is 0.5~1.2μm, the thickness of the first metal layer 2 is 30~50nm, the thickness of the base film 3 is 12~25μm, the thickness of the second metal layer 4 is 40~60nm, and the thickness of the adhesive layer is 3~8μm.

[0046] In addition, when the first metal layer and the second metal layer are mirror-finished metal layers with differentiated effects; the first metal layer is deposited by magnetron sputtering and the second metal layer is deposited by vacuum evaporation; or, the first metal layer and the second metal layer are deposited by magnetron sputtering or vacuum evaporation using different metals; or, the first metal layer is deposited by magnetron sputtering and the second metal layer is formed by chemical coloring and chemical etching based on magnetron sputtering.

[0047] The embodiments of the present invention employ different manufacturing processes for different methods of forming mirror and matte surfaces.

[0048] For example, when the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer, in the following embodiment, the first metal layer is deposited by magnetron sputtering, and the second metal layer is deposited by nanoimprinting + vacuum evaporation. The corresponding hot stamping film preparation process includes the following steps: (1) Base film pretreatment: both sides of the base film are subjected to corona or plasma cleaning.

[0049] (2) Fabrication of the first metal layer (mirror): A mirror metal layer is formed on one side of the base film by magnetron sputtering.

[0050] (3) Fabrication of the second metal layer (matte): First, a texture is created by nanoimprinting on the other side of the base film, and then a matte metal layer is formed by vacuum evaporation.

[0051] It should be noted that the order of steps (2) and (3) can be adjusted according to the configuration of the production equipment.

[0052] (4) Apply release layer: Apply release layer coating on the first metal layer and dry.

[0053] (5) Apply adhesive layer: Apply hot melt adhesive to the second metal layer and dry.

[0054] For example, when the first metal layer and the second metal layer are mirror-like metal layers with differentiated effects, in the following embodiment, the first metal layer (mirror-like) is formed by magnetron sputtering, and the second metal layer (mirror-like) is formed by chemical coloring + chemical etching (local aluminum washing), creating a visually differentiated mirror-like effect. The corresponding hot stamping film preparation process includes the following steps: (1) Base film pretreatment: both sides of the base film are subjected to corona or plasma cleaning.

[0055] (2) Making the second metal layer (mirror): A full mirror aluminum layer is plated on one side of the base film; a layer of chemical corrosion resistant UV ink is printed on the aluminum layer to form the desired pattern; the aluminum layer not protected by the ink is washed away with strong alkali solution; the protective ink is removed, and finally a mirror metal layer composed of "mirror aluminum" and "transparent window" is presented on one side of the base film. (3) Fabrication of the first metal layer (mirror): Aluminum is deposited on one side of the base film by magnetron sputtering to form a mirror metal layer.

[0056] (4) Apply release layer: Apply release layer coating on the first metal layer and dry.

[0057] (5) Apply adhesive layer: Apply hot melt adhesive to the second metal layer and dry.

[0058] The following are specific embodiments and comparative examples: Example 1 This embodiment of a hot stamping film with a double-sided differentiated metallic effect includes a release layer, a first metal layer (mirror finish), a base film, a second metal layer (matte finish), and an adhesive layer stacked sequentially in the thickness direction. The base film is a biaxially oriented polyester film (BOPET) with a thickness of 25 μm, and is corona-treated on both sides to a surface energy of 52 dyn / cm. The first metal layer (mirror finish) is aluminum-plated on one side of the base film using magnetron sputtering at a temperature of 80°C. The thickness of the first metal layer is 35 nm. The second metal layer… (Matte surface) Aluminum is deposited on the other side of the base film using nanoimprinting + vacuum evaporation. First, a matte texture is formed on the base film using a nanoimprinting roller (texture depth 150nm), and then an aluminum layer is deposited by vacuum evaporation. The thickness of the second metal layer is 50nm. An acrylic resin containing 0.4% azodicarbonamide is coated on the first metal layer and cured to form a release layer with a thickness of 0.8μm. A polyester hot melt adhesive (melting point 105℃) is coated on the second metal layer and cured to form an adhesive layer with a thickness of 5μm.

[0059] In this embodiment, the materials of the thermally decomposable protective layer include 100 parts of resin matrix, 10 parts of foaming agent, 5 parts of activator, 5 parts of crosslinking aid, 50 parts of inorganic filler, 20 parts of pigment, and 200 parts of solvent.

[0060] Example 2 Compared to Example 1, the difference lies in that the second metal layer (matte surface) is deposited directly using vacuum evaporation instead of nanoimprinting, with a thickness of 45nm, resulting in a softer semi-mirror effect. In this example, since the metal layer formed by vacuum evaporation has lower brightness than that formed by magnetron sputtering, it exhibits a softer, brighter effect. Therefore, this example achieves a differentiated effect of "high brightness" and "soft brightness" on both sides through the difference in the processes of the first and second metal layers.

[0061] In this embodiment, the materials of the thermally decomposable protective layer include 100 parts of resin matrix, 3 parts of foaming agent, 3 parts of activator, 2 parts of crosslinking aid, 30 parts of inorganic filler, 20 parts of pigment, and 300 parts of solvent.

[0062] Example 3 Compared to Example 1, the difference lies in that the first metal layer (mirror finish) is made of titanium nitride (TiN) instead of aluminum by magnetron sputtering, and the thickness of the first metal layer is 40 nm. The second metal layer (matte finish) is made of copper-zinc alloy (Cu:Zn=7:3) by nanoimprinting and vacuum evaporation, and the thickness of the second metal layer is 55 nm. This results in a bright gold appearance on the front of the hot stamping film and a bronze matte finish on the back.

[0063] In this embodiment, the materials of the thermally decomposable protective layer include 100 parts of resin matrix, 20 parts of foaming agent, 5 parts of activator, 10 parts of crosslinking aid, 70 parts of inorganic filler, 30 parts of pigment, and 400 parts of solvent.

[0064] Comparative Example 0 This comparative example uses a blank base film, specifically an untreated biaxially oriented PET base film with a thickness of 25 μm. This blank comparative example serves as a benchmark for performance testing, demonstrating that subsequent effects are all produced by the functional coating.

[0065] Comparative Example 1 This comparative example uses a traditional single-sided hot stamping film. The specific structure of this single-sided hot stamping film includes a release layer, a mirror aluminum layer, a PET base film, and an adhesive layer, which are stacked sequentially. The PET base film has a thickness of 25 μm, and the mirror aluminum layer has a thickness of 40 nm. In this single-sided hot stamping film, the mirror aluminum layer is deposited using vacuum evaporation. First, the mirror aluminum layer is deposited on one side of the PET base film. Then, a thermally decomposable release layer is coated on the mirror aluminum layer, and an adhesive layer is coated on the other side of the PET base film.

[0066] Comparative Example 2 This comparative example is a composite double-sided hot stamping film. The structure of this double-sided hot stamping film includes a protective layer, an aluminum layer A, a PET base film A, a composite adhesive layer, a PET base film B, and an aluminum layer B, stacked sequentially. The thickness of both PET base film A and PET base film B is 12 μm, and the thickness of both aluminum layer A and aluminum layer B is 40 nm. In this double-sided hot stamping film, two rolls of single-sided hot stamping film are first prepared. The first single-sided hot stamping film includes aluminum layer A and PET base film A, and the second single-sided hot stamping film includes PET base film B and aluminum layer B. Then, the PET base films of the two rolls of single-sided hot stamping film are laminated together on a laminating machine using polyurethane composite adhesive (dry adhesive weight 1.8 g / m²).

[0067] Comparative Example 3 The difference between this comparative example and Example 1 is that the protective layer in this example uses a traditional silicone release layer.

[0068] This comparative example is a hot stamping film with a double-sided differentiated metallic effect, comprising a release layer, a first metal layer (mirror finish), a base film, a second metal layer (matte finish), and an adhesive layer stacked sequentially in the thickness direction. The base film is a biaxially oriented polyester film (BOPET) with a thickness of 25 μm and a surface energy of 52 dyn / cm after double-sided corona treatment. The first metal layer (mirror finish) is aluminum-plated on one side of the base film using magnetron sputtering at a temperature of 80°C. The thickness of the first metal layer is 35 nm. The second metal layer (matte surface) is aluminum-plated on the other side of the base film using a combination of nanoimprinting and vacuum evaporation. First, a matte texture is formed on the base film using a nanoimprinting roller (texture depth 150nm), and then an aluminum layer is deposited by vacuum evaporation. The thickness of the second metal layer is 50nm. A release layer is formed by coating a silicone-containing acrylic resin onto the first metal layer and curing it. The thickness of the release layer is 0.8μm. A polyester hot melt adhesive (melting point 105℃) is formed by coating a polyester hot melt adhesive onto the second metal layer and curing it. The thickness of the adhesive layer is 5μm.

[0069] The performance of the embodiments and comparative examples was tested, and the results are shown in the table below:

[0070] It should be noted that the total thickness in the table above refers to the finished film thickness measured according to the national standard GB / T 6672-2001 (Mechanical Measurement Method for Determination of Thickness of Plastic Films and Sheets). In the actual production process, due to coating swelling, base film swelling, interface effects, rough texture caused by surface imprinting, tension changes during film production, coating drying and curing, etc., the actual measured total thickness of the finished film will differ from the theoretical total thickness in the examples.

[0071] The results showed that Comparative Example 2 had extremely low adhesion, only 0.09 N / 15 mm, due to the presence of the composite adhesive interface, and it whitened and peeled off after 200 bends. It also exhibited low efficiency and registration errors. In contrast, the present invention (Example 1) achieved an adhesion as high as 3.8 N / 15 mm because its metal layer and base film are bonded by PVD, resulting in performance far exceeding that of physical composites. Furthermore, the gloss difference between the two sides of Comparative Example 2 was only 3 GU, making them visually almost indistinguishable. In contrast, the present invention, through a completely different process, created a gloss difference of 68 GU, resulting in a striking contrast.

[0072] Comparative Example 3 uses a traditional release layer. Because traditional release layers do not have gas evaporation during hot stamping, and to prevent abnormal interlayer adhesion during transportation, the silicon content cannot be too high. Therefore, traditional release layers peel off more tightly, and their interlayer adhesion exceeds the allowable range. The presence of silicone may cause slight interfacial diffusion or the formation of an extremely thin interfacial layer, slightly interfering with high-precision optical contrast and causing a certain deviation in gloss. Silicone material itself is flexible, but its bonding force with the metal layer is weak; the interface easily becomes a stress concentration point during bending, leading to premature failure. Furthermore, traditional release layers require longer curing times due to the introduction of silicon (such as solvent evaporation or thermal curing), slowing down the overall production line speed. In contrast, the thermally decomposable protective layer of this invention achieves the effect of high cold peel force and low hot peel force after hot stamping.

[0073] Furthermore, Comparative Example 1 requires two hot stamping processes, which is inefficient and prone to registration errors. Since the double-sided differentiation effect of this invention is integrated onto the same base film, the double-sided differentiation effect can be completely transferred to the substrate simultaneously with a single hot stamping operation, solving the industry pain points of "low efficiency and difficulty in registration with secondary hot stamping."

[0074] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hot stamping film with a double-sided differentiated metallic effect, characterized in that, It includes a release layer, a first metal layer, a base film, a second metal layer, and an adhesive layer stacked in the thickness direction; The first metal layer is a mirror metal layer, and the second metal layer is a matte metal layer; or the first metal layer and the second metal layer are mirror metal layers with different effects. The gloss of the first metal layer is greater than that of the second metal layer.

2. The hot stamping film with double-sided differentiated metallic effect according to claim 1, characterized in that, When the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer, the surface gloss of the first metal layer is greater than 95 GU and the surface gloss of the second metal layer is less than 30 GU.

3. The hot stamping film with double-sided differentiated metallic effect according to claim 1, characterized in that, When the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; The first metal layer is deposited on one side of the base film by magnetron sputtering, and the second metal layer is deposited by vacuum evaporation after imprinting a texture onto the other side of the base film. or, Both the first and second metal layers are deposited using magnetron sputtering; the second metal layer reduces gloss by reacting with lower power, higher gas pressure, higher base film temperature, or by introducing oxygen or nitrogen compared to the first metal layer; or... Both the first metal layer and the second metal layer are deposited by vacuum evaporation. Before vacuum evaporation, the first metal layer is coated with a smooth base oil, and before vacuum evaporation, the second metal layer is coated with a base oil containing matting powder, or a texture is formed by embossing.

4. The hot stamping film with double-sided differentiated metallic effect according to claim 1, characterized in that, When the first metal layer and the second metal layer are mirror metal layers with differentiated effects; The first metal layer was deposited by magnetron sputtering, and the second metal layer was deposited by vacuum evaporation. Alternatively, the first metal layer and the second metal layer may be deposited using different metals via magnetron sputtering or vacuum evaporation. Alternatively, the first metal layer may be deposited by magnetron sputtering, and the second metal layer may be formed by chemical coloring and chemical etching based on magnetron sputtering.

5. The hot stamping film with double-sided differentiated metallic effect according to any one of claims 1-4, characterized in that, The release layer is a thermally decomposable protective layer, and its material is an acrylic resin solution containing 0.3%~0.5% thermally decomposable foaming agent.

6. The hot stamping film with double-sided differentiated metallic effect according to claim 5, characterized in that, The thermally decomposable protective layer comprises 100 parts of resin matrix, 1-20 parts of foaming agent, 0.3-10 parts of activator, 0.2-10 parts of crosslinking aid, 0-100 parts of inorganic filler, 10-50 parts of pigment, and 200-400 parts of solvent; Preferably, the resin matrix comprises one or more of ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer; the foaming agent is azodicarbonamide; the activator comprises one or more of zinc oxide and zinc stearate; the crosslinking aid is trimethylolpropane triacrylate; the inorganic filler comprises one or more of calcium carbonate and aluminum hydroxide; the pigment is titanium dioxide; and the solvent is one or more of toluene and ethyl acetate.

7. A process for preparing a hot stamping film with a double-sided differentiated metallic effect, characterized in that, Includes the following steps: Base film pretreatment: both sides of the base film are subjected to corona or plasma cleaning; A first metal layer and a second metal layer are deposited on both sides of the base film, respectively; the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; or the first metal layer and the second metal layer are mirror metal layers with different effects; the gloss of the first metal layer is greater than the gloss of the second metal layer. Applying release layer: Applying release layer coating to the first metal layer and drying; Apply adhesive layer: Apply adhesive material to the second metal layer and dry.

8. The preparation process of the hot stamping film with double-sided differentiated metallic effect according to claim 7, characterized in that, When the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; A first metal layer is formed on one side of the base film by magnetron sputtering; a texture is first formed on the other side of the base film by nanoimprinting, and then a second metal layer is formed by vacuum evaporation. Alternatively, a first metal layer is formed on one side of the base film by magnetron sputtering; and a second metal layer is formed on the other side of the base film by reacting with lower power, higher gas pressure, higher base film temperature, or by introducing oxygen or nitrogen gas to reduce gloss. Alternatively, a smooth base oil can be applied to one side of the base film before vacuum evaporation to form the first metal layer. On the other side of the base film, a base oil containing matting powder can be applied or a texture can be formed by embossing before vacuum evaporation to form the second metal layer.

9. The preparation process of the hot stamping film with double-sided differentiated metallic effect according to claim 7, characterized in that, When the first metal layer is a mirror metal layer and the second metal layer is a matte metal layer; A first metal layer is formed on one side of the base film by magnetron sputtering or vacuum aluminizing; a second metal layer is formed on the other side of the base film by magnetron sputtering or vacuum aluminizing, and a matte effect is achieved by chemical etching, laser engraving or coating matting.

10. The preparation process of the hot stamping film with double-sided differentiated metallic effect according to claim 7, characterized in that, When the first metal layer and the second metal layer are mirror metal layers with differentiated effects; The first metal layer is formed by magnetron sputtering, and the second metal layer is formed by vacuum evaporation. Alternatively, the first metal layer and the second metal layer can be formed by magnetron sputtering or vacuum evaporation using different metals; Alternatively, the first metal layer can be formed by magnetron sputtering, and the second metal layer can be formed by chemical coloring and chemical etching based on the magnetron sputtering.

Images