Pre-coat film for skin printing and method of manufacturing the same

Abstract

The application relates to a skin pre-coating film and a manufacturing method thereof, which comprises a hot melt adhesive layer, a substrate layer, a matte elastic layer and a skin layer which are sequentially stacked. The material for forming the matte elastic layer comprises a matte water-based polyurethane and a high-gloss water-based polyurethane, the matte water-based polyurethane is a self-matting resin, the skin layer adopts a solvent-free UV resin system, contains a UV resin, a photoinitiator and a functional additive selected from matting powder, fluff powder, PP short fibers and silicone microspheres, clear lines are formed by UV curing technology and skin roller pressing, and various touch feelings and adjustable gloss are realized. The 60-degree gloss of the matte elastic layer is in the range of 0.5-20 degrees, an elastic substrate and an adjustable visual background are provided. The manufacturing method comprises the steps of preparing coating liquids of various layers, coating and curing to form the matte elastic layer, embossing and curing to form the skin layer and the like. Through the cooperative design of the matte elastic layer and the skin layer, the visual level, the touch reality and the outline clarity of the skin effect are improved.

Description

Technical Field

[0001] This application relates to the field of pre-coated film technology, and in particular to a textured pre-coated film and its manufacturing method. Background Technology

[0002] Leather-textured packaging films, with their elegant and aesthetically pleasing visual effect, have been widely used in the high-end packaging sector. The realism of the leather texture directly determines the added value of the product. Currently, most mainstream leather-textured pre-coated films on the market use a process of laminating first and then embossing, forming the texture in one step on a laminating machine equipped with embossing rollers. This process has the advantages of being simple and low-cost, but its feel and elasticity cannot match the effect of genuine leather. As the market's requirements for packaging quality increase, the market is placing higher demands on leather-textured pre-coated film products, expecting to obtain a more realistic leather texture.

[0003] In existing technologies, some solutions aim to improve the leather-textured effect by optimizing the design of the substrate layer and the hot melt adhesive layer. For example, one patent uses a pre-coating and then embossing method, where the hot melt adhesive layer uses a modified compatibilizer and an ethylene-vinyl acetate (EVA) polymer formulation, and the substrate layer is a combination of biaxially oriented polypropylene (BOPP) and single-sided polyethylene (PE). By improving the bonding strength with the ink and paper, the embossed texture is less prone to springback, thus maintaining the leather-textured shape. However, this method has the following drawbacks: the texture is the result of the joint deformation of the paper, hot melt adhesive, and BOPP substrate. Due to the high physical stability and mechanical strength of the BOPP film itself, yield stress is generated during the embossing process to resist the deformation caused by embossing, resulting in insufficient definition and clarity of the embossed outline. In addition, the leather-textured pre-coated film prepared by this process lacks the feel and elasticity of genuine leather, and the uneven areas of the leather texture do not present the necessary gloss differences, resulting in a less aesthetically pleasing final product.

[0004] Another mainstream method involves pre-coating BOPP film and then directly hot-pressing it. Under heat, the ethylene-vinyl acetate (EVA) hot melt adhesive melts and deforms, creating patterns under the action of embossing rollers, followed by cooling and setting. However, the yield stress of the BOPP film resists embossing deformation, leading to a decrease in the clarity of the pattern outline. Furthermore, the gloss of the BOPP substrate is limited by its material properties, making it difficult for embossing rollers to create a significant gloss contrast on its surface. This results in a generally uniform gloss across the raised and recessed areas of the pattern, lacking the visual depth of genuine leather texture and producing an overall poor leather-like effect.

[0005] In existing leather-textured pre-coating technologies, the texture outlines are easily affected by substrate stress due to the mechanical properties of substrates such as BOPP, resulting in insufficient clarity. Furthermore, the finished products lack the tactile elasticity and visual gloss levels of genuine leather, failing to meet market demands for high-end leather-textured pre-coatings. Therefore, there is an urgent need to develop a new material system or technological method that can balance clear leather texture outlines, a realistic leather elastic feel, and gloss differences in uneven areas, thereby comprehensively enhancing the biomimetic texture and product value of leather-textured pre-coatings. Summary of the Invention

[0006] The purpose of this application is to provide a leather-textured pre-coated film and its manufacturing method, which overcomes the problems of unclear embossing contours, lack of elasticity and tactile feel, and insufficient gloss layering in the prior art through the synergistic design of a matte elastic layer and a leather-textured layer, thereby improving the realism of the leather-textured effect in both visual and tactile aspects. This purpose is achieved through the following technical solution: the leather-textured pre-coated film of this application comprises a hot melt adhesive layer, a substrate layer, a matte elastic layer, and a leather-textured layer stacked sequentially. The material forming the matte elastic layer includes matte waterborne polyurethane, wherein the matte waterborne polyurethane is a self-matting resin; The materials forming the textured layer include UV resin, photoinitiator, and functional additives, wherein the functional additives are selected from one or more of the following materials: matting powder, fluff powder, PP short fiber, and organosilicon microspheres.

[0007] In one embodiment, the material forming the matte elastic layer, by weight, includes: 1-90 parts of matte waterborne polyurethane, 0.02-0.1 parts of curing agent, and 0-10 parts of high-gloss waterborne polyurethane; the material forming the textured layer, by weight, includes: 2-90 parts of UV resin, 0.05-0.2 parts of photoinitiator, 0-2 parts of matting powder, 0-1 part of fluff powder, 0-1 part of PP short fiber, and 0-1 part of silicone microspheres.

[0008] In one embodiment, the matte waterborne polyurethane has an elongation at break of >400%, and the particle size of the microparticles in the matte waterborne polyurethane is in the range of 500nm-2000nm.

[0009] In one embodiment, the 60° gloss of the matte elastic layer is in the range of 0.5°-20°.

[0010] In one embodiment, the gloss difference between the matte elastic layer and the textured layer is in the range of 3°-15°.

[0011] In one embodiment, the material of the substrate is selected from one or more of the following materials: PET, BOPP, CPP, PA, PVC or PC, and the thickness of the substrate layer is in the range of 12μm-100μm.

[0012] In one embodiment, the thickness of the matte elastic layer is in the range of 3 μm to 10 μm.

[0013] This application further provides a method for preparing a textured pre-coated film, including: To prepare a matte elastic layer coating liquid, a matte waterborne polyurethane emulsion and a curing agent are mixed evenly, wherein the matte waterborne polyurethane is a self-matting resin. To prepare the leather texture coating solution, UV resin, photoinitiator and functional additives are mixed evenly, wherein the functional additives are selected from one or more of the following materials: matting powder, fluff powder, PP short fiber, and organosilicon microspheres. The matte elastic layer coating liquid is applied to the substrate layer and cured to form a matte elastic layer on the substrate layer. The texture coating liquid is applied to the matte elastic layer to press out a pattern and then cured to form a texture layer on the matte elastic layer.

[0014] In one embodiment, a hot melt adhesive layer is also formed on the side of the substrate layer opposite to the matte elastic layer by a coating process.

[0015] In one embodiment, the particle size of the matte waterborne polyurethane is in the range of 500nm-2000nm, and a high-gloss waterborne polyurethane emulsion is also added to the matte elastic layer coating liquid.

[0016] Compared with the prior art, this application has the following beneficial effects: This application effectively enhances the elastic feel by adding a matte elastic layer as the bottom layer of the textured layer. The textured layer can achieve a soft touch, a rough hair-like feel, and a smooth feel by adding fluff powder, PP short fibers, and silicone microspheres, thereby obtaining a textured film with elasticity and tactile feel.

[0017] This application, while achieving a tactile feel using the above technologies, presents a difference in light and shadow by designing a difference in gloss between the elastic layer and the textured layer. This highlights the visual impact between the matte elastic layer and the textured layer, significantly enhancing aesthetics and leather reproduction. The gloss in the matte elastic layer is adjusted by the ratio of water-based polyurethane resin and high-gloss resin, while the gloss in the textured layer is adjusted by the ratio of UV varnish and matte powder after lamination. The gloss of the elastic layer can be lower or higher than that of the textured layer, presenting the same leather texture but with different light and shadow effects.

[0018] The textured layer in this application is formed by applying a textured coating liquid to a textured roller, followed by instant UV curing and peeling. During this process, the texture is shaped through the curing and setting of the coating liquid. Without a substrate intervening, the texture effect is more clearly presented, avoiding the problem of unclear outlines caused by the substrate layer's yield stress resistance deformation. This results in a more distinct textured effect. Rapid curing via UV light eliminates the need for a heated drying tunnel, helping to reduce pollutant emissions, lower equipment energy consumption, and improve production efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the leather texture pre-coated film in one embodiment of this application; Figure 2 This is a schematic flowchart of a method for manufacturing a textured pre-coated film according to one embodiment of this application.

[0020] Explanation of reference numerals in the attached drawings: 100, substrate layer; 200, matte elastic layer; 300, textured layer; 400, hot melt adhesive layer. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0022] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] To address the problems of unclear leather texture outlines, lack of elasticity, and insufficient gloss levels caused by substrate yield stress in existing technologies, this application improves the leather texture pre-coated film and its manufacturing method, which will be described in detail below with reference to specific embodiments. The leather texture pre-coated film of this application generally adopts a four-layer structure consisting of a hot melt adhesive layer, a substrate layer, a matte elastic layer, and a leather texture layer, stacked sequentially. The matte elastic layer is achieved by compounding matte waterborne polyurethane with high-gloss waterborne polyurethane of specific particle sizes, providing underlying elasticity and adjustable gloss. The leather texture layer is formed by a leather texture coating liquid system containing functional additives through a UV-cured embossing process, giving it clear leather texture outlines and diverse tactile sensations.

[0025] The following section will elaborate on the material selection, formulation range, preparation process parameters, and synergistic effects of each functional layer. Please refer to [link / reference]. Figure 1 In a preferred embodiment of this application, the textured pre-coated film includes a hot melt adhesive layer 400, a substrate layer 100, a matte elastic layer 200, and a textured layer 300 stacked sequentially. The material forming the matte elastic layer 200 includes matte waterborne polyurethane, which is a self-matting resin. The material forming the textured layer 300 includes UV resin, photoinitiator, and functional additives. The functional additives are selected from one or more of the following materials: matting powder, fluff powder, PP short fiber, and organosilicon microspheres.

[0026] The textured layer 300 uses a solvent-free UV resin system (such as polyurethane-modified acrylate), combined with a photoinitiator and a series of functional additives, and is formed through UV curing technology, taking advantage of the high production efficiency and solvent-free emission characteristics of UV curing. The surface gloss is controlled by adding matting powder (such as Evonik OK607, OK500, OK412 and other hydrophobic silica), contributing a special surface feel. The gloss is inversely proportional to the amount of matting powder added, which allows the gloss of the textured layer 300 to be designed independently of the matte elastic layer 200. The difference in gloss between the two layers together creates the visual layering of the texture.

[0027] Specific tactile sensations can be directly imparted to the coating surface by adding different types of additives. Adding fluff powder utilizes its micro-elasticity properties formed in the cured coating to give the surface a delicate and soft feel. Adding short polypropylene (PP) fibers utilizes the microscopic protrusion structure formed by the fibers in the coating to achieve a rough or hair-like feel. Adding silicone microspheres utilizes their excellent smoothness and low coefficient of friction to give the surface a good smoothness. Specifically, the fluff powder has a Tg range between -40 and 3°C and a particle size between 4 and 20 μm. Preferably, the fluff powder is one or a combination of several of the following: Genshang AK-800TR, Genshang JP-800T, and Genshang C-400T. The silicone microspheres are of one or a combination of two of the following types: acrylate-silicone microspheres or pure silicone microspheres. Preferably, the silicone microspheres are of one or a combination of two of the following types: Yongqi HS1730E and Yongqi R100. The matting agent is of one or a combination of several of the following types: hydrophobic silica and modified hydrophobic silica. Preferably, the matting agent is of one or a combination of two of the following types: Evonik OK607, Evonik OK500, and Evonik OK412. The PP short fibers have a fineness of 3-6 dte textured pre-coated film, a length of <2 mm, and a fiber diameter of 5-20 μm.

[0028] The materials forming the matte elastic layer, by weight, include: 1-90 parts of matte waterborne polyurethane, 0.02-0.1 parts of curing agent, and 0-10 parts of high-gloss waterborne polyurethane; the materials forming the textured layer, by weight, include: 2-90 parts of UV resin, 0.05-0.2 parts of photoinitiator, 0-2 parts of matting powder, 0-1 part of fluff powder, 0-1 part of PP short fiber, and 0-1 part of silicone microspheres. The matte elastic layer 200 is a mixture of waterborne polyurethane emulsion, curing agent, and high-gloss polyurethane emulsion, which is coated, dried, and wound up. It is achieved by gravure coating of matte waterborne polyurethane emulsion with curing agent onto the substrate. The matte waterborne polyurethane is a self-matting resin. By mixing with high-gloss waterborne polyurethane emulsion, the gloss can be improved, achieving a gloss of 60° that is adjustable between 0.5° and 20°, providing a designable underlying visual background for the subsequent textured layer 300. Based on the above scheme, the gloss difference between the matte elastic layer and the textured layer is further selected within the range of 3 to 15° to achieve a better realism of the textured effect.

[0029] Furthermore, the polyurethane material selected for this layer has an elongation at break of at least 400%, enabling it to undergo significant deformation and recover under external force, simulating the elastic feel of leather. The technical effect of the matte elastic layer 200 relies on the synergistic effect of its thickness and the physical properties of the selected material. Both matte and high-gloss waterborne polyurethanes have an elongation at break of at least 400%. This high elongation at break ensures that the material itself possesses excellent elastic recovery capabilities. When this characteristic is combined with a coating thickness of 3μm-10μm, the coating is sufficient to form an elastomer of sufficient thickness at the microscopic level, thereby providing the final product with a moderate elasticity similar to the feel of leather at the macroscopic level.

[0030] Furthermore, the matte elastic layer 200 is based on a matte waterborne polyurethane emulsion with a specific particle size range of 500nm to 2000nm. The matte waterborne polyurethane is a self-matting resin, and the particle size is controlled within the range of 500nm to 2000nm, which is beneficial to achieving its self-matting properties and obtaining low gloss. The 60° gloss of the final coating can be systematically adjusted, making it adjustable within the range of 0.5° to 20°.

[0031] The substrate material is selected from one or more of the following materials: PET, BOPP, CPP, PA, PVC, or PC. The thickness of the substrate layer 100 is in the range of 12μm-100μm. It mainly plays a supporting role in the overall structure, providing a stable base for the coating of the matte elastic layer 200 and the lamination of the hot melt adhesive layer 400. The hot melt adhesive layer 400 is made of ethylene-vinyl acetate copolymer resin (EVA) and is melt-extruded to the blank side of the substrate, ensuring that its thickness accounts for more than 30% of the overall structural thickness. The EVA hot melt adhesive layer 400 plays the role of bonding the printed material in the structure, and its adhesive strength is proportional to the coating thickness within a certain range.

[0032] In the layered structure of the textured pre-coated film, the thickness of the matte elastic layer 200 is set in the range of 3-10 μm. Specifically, if the thickness of this layer is less than 3 μm, the coating may be too thin to provide uniform and sufficient elastic support, and its matte effect may also be affected. If the thickness exceeds 10 μm, it will not only increase the material cost, but may also have an adverse effect on the overall flexibility of the film layer, and may introduce undesirable deformation during the subsequent imprinting and curing process of the textured layer 300.

[0033] Please see Figure 2This application further provides a method for preparing a textured pre-coated film, comprising: preparing a matte elastic layer coating liquid by uniformly mixing a matte aqueous polyurethane emulsion and a curing agent, wherein the matte aqueous polyurethane is a self-matting resin; preparing a textured layer coating liquid by uniformly mixing a UV resin, a photoinitiator, and a functional additive, wherein the functional additive is selected from one or more of the following materials: matting powder, fluff powder, PP short fiber, and organosilicon microspheres; coating the matte elastic layer coating liquid onto a substrate layer 100 and curing it to form a matte elastic layer 200 on the substrate layer 100; and applying the textured layer coating liquid onto the matte elastic layer 200, pressing out a pattern, and curing it to form a textured layer 300 on the matte elastic layer 200.

[0034] In the preparation process of the leather-textured pre-coated film, the structure is optimized by controlling the coating preparation and curing steps. The matte waterborne polyurethane is a self-matting resin with a particle size controlled within the range of 500nm to 2000nm, which is beneficial for achieving its self-matting properties and obtaining low gloss. The 60° gloss of the final coating can be systematically adjusted, making it adjustable within the range of 0.5° to 20°. In the coating liquid component, the addition of a curing agent (such as one or a combination of two of carbodiimide, aziridine, and isocyanate) promotes the crosslinking reaction of the polyurethane system, which can improve the durability and mechanical stability of the coating. UV curing is preferred. Coating process parameters, such as coating amount controlled at 1-10 g / m², and coating environment and oven temperature controlled at 20-30℃ and 50-80℃ respectively, aim to ensure stable leveling of the coating liquid and sufficient evaporation of the solvent, thereby forming a uniform and stable matte elastic layer 200 with a typical thickness of 3-10μm. The polyurethane material constituting this layer is required to have an elongation at break of at least 400% to provide a leather-like undercoat for the pre-coated film.

[0035] The leather-textured coating solution is composed of solvent-free UV resin, photoinitiator, and a series of functional additives. Using a solvent-free UV resin system (such as polyurethane-modified acrylate) reduces pollutant emissions. Surface gloss is controlled by adding matting powder. Gloss is inversely proportional to the amount of matting powder added; by controlling its addition within the range of 0-2% by weight, precise adjustment of the leather-textured layer's gloss level to 300 is possible. Different types of additives are added to directly impart specific tactile sensations to the coating surface. Adding fuzz powder utilizes its micro-elasticity formed in the cured coating to impart a delicate, soft feel; adding polypropylene utilizes the microscopic protrusion structure formed by fibers in the coating to achieve a rough and hair-like texture; adding silicone microspheres utilizes their excellent smoothness and low coefficient of friction to impart a smooth surface.

[0036] In the film-forming process, a prepared matte elastic layer coating liquid is applied to the substrate and dried to form a continuous underlayer. Subsequently, a leather texture layer coating liquid is applied to the matte elastic layer 200. After the coating is wetted and leveled, it is pressed by a chrome-plated steel leather texture roller and instantly passed through a UV curing unit, for example, using a combination of LED lights and medium-pressure mercury lamps, with irradiation conditions of 300-500 MJ / cm². After curing, it separates from the texture roller. Utilizing the high production efficiency of UV curing technology facilitates rapid production. The leather texture is formed by the curing and setting of the UV varnish, which helps overcome the problem of unclear outlines caused by the yield stress resistance deformation of the substrate (such as BOPP), thus achieving a more defined leather texture effect. Simultaneously, the designable difference in gloss between the leather texture layer 300 and the matte elastic layer 200 together constructs the visual layering of the leather texture.

[0037] In a further technical solution, a high-gloss waterborne polyurethane emulsion is added to the matte elastic layer coating liquid. Specifically, the matte elastic layer coating liquid is prepared by uniformly mixing specific components of the matte waterborne polyurethane emulsion, curing agent, and high-gloss waterborne polyurethane emulsion. In this specific embodiment, the materials of the matte elastic layer coating liquid, by weight, include: 1-90 parts of matte waterborne polyurethane, 0.02-0.1 parts of curing agent, and 0.1-10 parts of high-gloss waterborne polyurethane. The preparation method of this leather-textured pre-coated film utilizes the synergistic design and control of the material formulation, coating process, and curing method of the matte elastic layer 200 and the leather-textured layer 300. It comprehensively utilizes polyurethane resin with specific particle size, a matte system with adjustable gloss, various functional additives, and efficient UV curing technology, enabling the final product to visually present rich gloss levels and tactilely simulate various realistic leather textures.

[0038] Furthermore, ethylene-vinyl acetate copolymer resin (EVA) can be laminated to the blank side of the substrate using melt extrusion to form a hot melt adhesive layer 400. Ensuring the EVA layer accounts for more than 30% of the overall structural thickness is crucial because the adhesive strength of the hot melt adhesive to printed materials is directly proportional to its thickness within a certain range; sufficient thickness is an important factor in ensuring a strong bond between the adhesive and the printed material.

[0039] In a specific method example, the steps are as follows: Preparation of matte elastic layer coating liquid: Aqueous polyurethane emulsion, curing agent, and high-gloss polyurethane emulsion are added sequentially to a mixing tank, stirred, and then filtered to obtain the final product. The coating mixture consists of the following components by weight: 1-90 parts of aqueous polyurethane emulsion, 0.02-0.1 parts of curing agent, and 0-10 parts of high-gloss polyurethane emulsion. The stirring speed is 300-800 r / min, and the mixture is stirred for 20 min. The final product is obtained after filtration.

[0040] The waterborne polyurethane emulsion is an anionic or nonionic polyurethane dispersion with an elongation between 400-1000% and a dry film gloss of <0.5° at 60°. The matte waterborne polyurethane is a self-matting resin; gloss can be improved by blending with high-gloss waterborne polyurethane emulsions, achieving an adjustable gloss level between 0.5-20° at 60°. The coating amount is 1-10 g / m², and the coating roller line count is 360-80 L / inch. The coating roller volume is 5-60 cm³ / m². The product is then dried and wound up. The coating environment and coating solution temperature are controlled within the range of 20-30°C. The drying tunnel temperature is controlled within the range of 50-80°C. The curing agent is one or a combination of two of carbodiimide, aziridine, and isocyanate. The high-gloss polyurethane emulsions mentioned are one or a combination of two of Wanhua Crysol® 6140, Wanhua Adwel® 1665, and Tekspro® 5219.

[0041] Matte elastic layer 200 coating: The BOPP substrate is unwound and loaded onto the machine. The mixed coating liquid is applied to the substrate using a micro-gravure or gravure coating method. After drying, it is rewound to obtain the final product.

[0042] Preparation of leather texture coating solution: In a mixing tank, solvent-free UV resin, matting agent, fluffing agent, PP short fiber, silicone microspheres, and photoinitiator are added sequentially. After stirring, the textured coating solution is obtained. The textured coating solution consists of the following components by weight: 2-90 parts solvent-free UV resin, 0-2 parts matting agent, 0-1 part fluffing agent, 0-1 part PP short fiber, 0-1 part silicone microspheres, and 0.05-0.2 parts photoinitiator. Textured layer 300: The amount of matting agent added in the textured coating solution is controlled to adjust the gloss. Gloss is inversely proportional to the amount of matting agent added. The amount added is 0-2% by weight. The stirring speed is 300-800 r / min. The stirring time is 1 hour.

[0043] Leather texture layer 300 coating: A leather-textured coating liquid is applied to one side of the matte elastic layer 200 obtained by winding. After the coating is wetted and leveled, it is pressed together by a customized upper embossing roller and lower drive roller. At this time, the leather-textured coating liquid is still in an uncured state. Then, it passes through the UV curing unit for a short time, peels off and leaves the embossing roller, and is then wound up to obtain the final product. After the leather-textured coating liquid is pressed to create a pattern, it is cured and shaped by UV and other units in a short time. After UV curing, the leather-textured coating is fully cured, does not stick together, and can be directly wound up. After curing, the wear resistance performance of the composite steel wool is qualified after more than 2000 cycles of rubbing with a 200g weight. The gloss of the leather-textured layer 30060° is adjustable from 0.5-10°.

[0044] The matte elastic layer 200 obtained by winding is coated with a leather-textured coating liquid. After the coating is wetted and leveled, it is pressed by a customized patterned roller drive roller, instantly passes through the UV curing unit, and then separates from the patterned roller before being wound up. The UV irradiation conditions in the curing area are: 300-500 MJ / cm2, 3-21 lamps, power on 50-100%, the light source is a combination of LED lamps and medium-pressure mercury lamps, and the machine speed control range is 80-120 m / min.

[0045] The hot melt adhesive layer 400 uses ethylene-vinyl acetate copolymer resin (EVA) which is melt-extruded onto the blank side of the substrate, ensuring that the ethylene-vinyl acetate copolymer resin (EVA) accounts for more than 30% of the overall structural thickness. The bonding strength of the printed material is directly proportional to the EVA thickness within a certain range. The resin used is a solvent-free UV resin, which is one or a combination of several of polyurethane-modified acrylate, polyester acrylate, epoxy acrylate, and silicone-modified acrylate. The textured layer 300 uses UV curing technology; the solvent-free formulation system has low odor and reduces pollutant emissions. Rapid curing results in high production efficiency, eliminates the need for heated drying tunnels, and reduces equipment energy consumption.

[0046] Similarly, the specific materials added include one or a combination of two of the following: high-gloss polyurethane emulsions: Wanhua Crysol® 6140, Wanhua Adwel® 1665, and Tekspro® 5219; the photoinitiator is one or a combination of several of the following: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-acetone, 1-hydroxycyclohexylphenyl ketone, and methyl benzoylformate; the fluff powder has a Tg range of -40 to 3°C, a particle size of 4-20 μm, and the fluff powder model is one or a combination of several of the following: Genshang AK-800TR, Genshang JP-800T, and Genshang C-400T; the organosilicon micro... The microspheres are made of one or a combination of two of the following: acrylate-organic silicon microspheres or pure organosilicone microspheres. The organosilicone microspheres are made of one or a combination of two of the following: Yongqi HS1730E and Yongqi R100. The matting agent is made of one or a combination of several of the following: hydrophobic silica and modified hydrophobic silica. The matting agent is made of one or a combination of two of the following: Evonik OK607, Evonik OK500, and Evonik OK412. The PP short fibers have a fineness of 3-6 dte textured pre-coated film, a length of <2 mm, and a fiber diameter of 5-20 μm.

[0047] In one embodiment, a hot melt adhesive layer 400 is formed on the side of the substrate layer 100 opposite to the matte elastic layer 200 using a coating process. Ethylene-vinyl acetate copolymer resin (EVA) is melt-extruded onto the blank side of the substrate, serving to bond the printed material within the structure. The ethylene-vinyl acetate polymer is melt-extruded and then laminated onto the blank side surface of the BOPP substrate using a coating process to form the hot melt adhesive layer 400. After cooling, it is wound up.

[0048] In the preparation process of the textured pre-coated film, a textured roller is used to emboss the pattern and then cured with ultraviolet light. The textured roller is preferably made of chrome-plated steel. The chrome plating gives the roller surface high hardness and wear resistance, maintaining the accuracy and consistency of the texture, which helps in the smooth peeling of the embossed pattern from the UV coating. Embossing and UV curing are closely linked in sequence. Specifically, the prepared textured coating liquid (i.e., UV varnish) is applied to the matte elastic layer 200. After it is wetted and leveled, it is pressed together by the textured roller and the lower drive roller. At this time, the UV varnish is still in an uncured state and has good fluidity. Under pressure, it fully fills the texture of the roller, thus replicating a clearly defined pattern. Subsequently, the coating carrying the pattern passes instantly through the UV curing unit, undergoes a cross-linking reaction after being irradiated with ultraviolet light, and quickly sets, then separates from the roller. With this instant curing method, the formation of the texture depends on the curing and shaping of the UV varnish. This helps to overcome the problem of unclear outlines caused by the yield stress resistance deformation of the substrate (such as BOPP), thereby obtaining a more distinct texture effect. Under the premise of efficient production, it can ensure that the texture layer 300 obtains a clear outline and stable pattern.

[0049] In the preparation process of the leather-textured pre-coated film, the matte elastic layer coating liquid and the leather-textured layer coating liquid have specific components and their weight ratios. Optimizing the component ratios achieves superior visual and tactile functions. The matte elastic layer coating liquid uses matte waterborne polyurethane (1-90 parts) as the main resin, with a particle size controlled within the range of 500nm to 2000nm. High-gloss waterborne polyurethane (0-10 parts) is used to finely adjust the gloss of the elastic layer. By changing its mixing ratio with the matte resin, the 60° gloss of the matte elastic layer 200 can be adjusted. The coating liquid contains 0.02-0.1 parts of a curing agent, such as carbodiimide or isocyanate compounds. This weight ratio of curing agent is sufficient to ensure effective crosslinking density while avoiding excessive amounts that could affect the coating's flexibility. Combined with the requirement that polyurethane materials have an elongation at break greater than 400%, this ensures the coating possesses high elasticity, providing a leather-like underlayer feel to the pre-coated film. The textured coating liquid contains 2-90 parts of solvent-free UV resin and 0.05-0.2 parts of photoinitiator. By adding 0-2 parts of matte powder, 0-1 parts of fluffing powder, 0-1 parts of polypropylene (PP) short fibers, and 0-1 parts of silicone microspheres, the surface feel is effectively altered, while excessive addition is avoided as it could affect the continuity and mechanical properties of the coating. By setting the above components and precise weight ranges for both the matte elastic coating liquid and the textured coating liquid, the components can work synergistically within the system, achieving both underlying elasticity and adjustable gloss, as well as clear surface texture, adjustable gloss, and diverse tactile sensations. Together, these elements give the pre-coated film a realistic visual and tactile effect.

[0050] The coating amount of the matte elastic layer coating liquid is controlled within the range of 1-10 g / m² to ensure that the formed matte elastic layer 200 achieves a suitable dry film thickness of 3-10 μm. If the coating amount is less than 1 g / m², the resulting coating may be too thin to form a continuous film layer, affecting its function as an elastic underlayer, and making it difficult to achieve fine adjustment of gloss from 0.5° to 20° by blending high-gloss resins. If the coating amount exceeds 10 g / m², it will result in an excessively thick coating, increasing material costs, adversely affecting the overall flexibility of the film layer, and potentially prolonging drying time, thus affecting production efficiency.

[0051] Setting the coating amount of the textured layer coating liquid within the range of 3-8 g / m², and preferably using a 90 L / inch (i.e., 90 lines per inch) coating roller, is a crucial process combination for achieving a clear leather texture effect and a specific surface feel. The textured layer 300 needs to have sufficient thickness to accommodate functional additives such as matte powder, fluff powder, PP short fibers, and silicone microspheres, and ensure that it can fully fill the pattern of the embossing roller during embossing. A coating amount below 3 g / m² may result in an insufficient coating to completely replicate the pattern of the embossing roller, and the additives may be sparsely distributed, making it difficult to achieve the desired feel; while a coating amount above 8 g / m² may result in an excessively thick coating that affects the penetration depth of UV light, leading to incomplete curing and potentially blurring the leather texture outline. Using a 90 L / inch coating roller optimizes the wet film thickness and uniformity transferred to the substrate, and the wet film thickness is controlled by precisely adjusting components such as the coating roller and metering roller. Correlate the coating amount with the coating roller count to achieve a stable and design-compliant 300mm leather texture layer thickness. This ensures the clarity of the leather texture outline, thorough curing, and surface effects of functional additives during subsequent UV embossing processes. The synergistic control of coating amount for these two layers collectively guarantees the overall performance of the leather texture pre-coated film in terms of visual gloss levels, tactile elasticity, and leather texture clarity. Specific Implementation The following will further introduce some specific implementation methods to provide a more detailed explanation of the technical solution of this application.

[0053] Example 1 A textured pre-coated film according to this embodiment comprises the following components in parts by weight: Matte elastic layer: 90 parts waterborne polyurethane emulsion, 0.1 parts curing agent, and 0.5 parts high-gloss polyurethane emulsion.

[0054] Skin texture layer: 90 parts solvent-free UV resin, 2 parts matting powder, 1 part fluff powder, and 2 parts UV photoinitiator.

[0055] The UV photoinitiator was 1173, purchased from Zhanxin. The high-gloss polyurethane emulsion was Tekspro® 5219, purchased from Wanhua Chemical. The matting agent was OK500, purchased from Evonik. The fluffing agent was AK-800TR, purchased from Genshang.

[0056] The preparation method of this embodiment includes the following key steps: S1. Preparation of the matte elastic layer: At a stirring speed of 400 rpm, accurately weigh the water-based polyurethane emulsion into a container and stir for 10 minutes; then add the high-gloss polyurethane and curing agent sequentially, and stir for 30 minutes. Finally, filter through a 100-mesh screen to obtain the matte elastic coating liquid. Select a substrate, apply the coating liquid via microgravure coating, and then dry and rewind.

[0057] S2. Preparation of the leather texture layer: Stir at 400 rpm, accurately weigh and sequentially add solvent-free UV resin, matting powder, and fluff powder, then stir for 30 minutes. Add UV photoinitiator and stir for 10 minutes. Finally, filter through a 100-mesh filter to obtain the leather texture coating liquid. Using the above semi-finished roll, after coating with the leather texture coating liquid, first press it through a leather texture roller and then instantly cure it under a UV lamp.

[0058] S3. Preparation of hot melt adhesive layer: The ethylene-vinyl acetate polymer is heated, melted, and extruded, then laminated onto the other side of the above-mentioned textured layer semi-finished product using a coating method to form a hot melt adhesive layer. After cooling, it is wound up.

[0059] Example 2 A textured pre-coated film according to this embodiment comprises the following components in parts by weight: Matte elastic layer: 90 parts waterborne polyurethane emulsion, 0.1 parts curing agent, and 0.5 parts high-gloss polyurethane emulsion.

[0060] Skin texture layer: 90 parts solvent-free UV resin, 2 parts matting powder, 0.5 parts silicone microspheres, and 2 parts UV photoinitiator.

[0061] The UV photoinitiator was 1173, purchased from Zhanxin. The high-gloss polyurethane emulsion was Tekspro® 5219, purchased from Wanhua Chemical. The matting agent was OK500, purchased from Evonik. The silicone microspheres were R100, purchased from Yongqi.

[0062] The preparation method in this embodiment is the same as in S1, but the difference lies in the formulation.

[0063] Example 3 A textured pre-coated film according to this embodiment comprises the following components in parts by weight: Matte elastic layer: 90 parts waterborne polyurethane emulsion, 0.1 parts curing agent.

[0064] Skin texture layer: 90 parts solvent-free UV resin, 0.03 parts matting powder, 1 part fluff powder, and 2 parts UV photoinitiator.

[0065] The UV photoinitiator was 1173, purchased from Zhanxin. The matting agent was OK500, purchased from Evonik. The fluffing agent was AK-800TR, purchased from Genshang.

[0066] The preparation method in this embodiment is the same as in S1, but the difference lies in the formulation.

[0067] Comparative Example 1 This comparative example of a leather-textured pre-coated film comprises the following components in parts by weight: Skin texture layer: 90 parts solvent-free UV resin, 0.03 parts matting powder, 1 part fluff powder, and 2 parts UV photoinitiator.

[0068] The UV photoinitiator was 1173, purchased from Zhanxin. The matting agent was OK500, purchased from Evonik. The fluffing agent was AK-800TR, purchased from Genshang.

[0069] The preparation method of this comparative example does not include a matte elastic layer; the other steps are the same as in S1.

[0070] Each embodiment was tested, including the gloss of the matte elastic layer at 60°, the gloss of the matte elastic layer + textured layer at 60°, the coefficient of friction of the matte elastic layer, the coefficient of friction of the matte elastic layer + textured layer, and the feel. The relevant test results are summarized in Table 1.

[0071] Table 1 Summary of Test Results for Each Implementation Method Based on the test results above, compared with Example 1, the matte elastic layer formula remains unchanged in Example 2, the texture layer replaces the fluff powder with organosilicon microspheres, and other preparation processes remain unchanged. According to the test data in Table 1, the overall gloss remains unchanged. Replacing the fluff powder with organosilicon microspheres reduces the overall coefficient of friction of the material, and the feel changes from soft to smooth.

[0072] Compared to Example 1, Example 3 adjusted the proportion of high-gloss polyurethane emulsion in the matte elastic layer to reduce gloss, while the amount of matte powder in the textured layer was reduced to increase gloss. Other preparation processes remained unchanged. The test data in Table 1 shows a difference in gloss, but the final feel remains largely the same.

[0073] Compared to Example 1, Comparative Example 1 lacks the matte elastic layer design, and the leather texture layer preparation process is the same as in Example 1. As a result, the final product no longer has elasticity and lacks texture.

[0074] As described above, this application provides a textured pre-coated film and its manufacturing method. The textured pre-coated film adopts a four-layer structure stacked sequentially, including a hot melt adhesive layer, a substrate layer, a matte elastic layer, and a textured layer. The substrate layer is made of one or more materials selected from PET, BOPP, CPP, PA, PVC, or PC, with a thickness of 12μm-100μm, serving a supporting function. The hot melt adhesive layer is formed by melt extrusion of ethylene-vinyl acetate copolymer resin, and its thickness accounts for more than 30% of the overall structural thickness, ensuring strong adhesion to printed materials.

[0075] The matte elastic layer is composed of matte waterborne polyurethane and high-gloss waterborne polyurethane with a specific particle size range of 500nm-2000nm, mixed in a weight ratio of 1-90:0-10, and formed by cross-linking and curing with the addition of 0.02-0.1 parts by weight of curing agent. This layer has a thickness of 3μm-10μm, an elongation at break greater than 400%, and an adjustable gloss level of 60° within the range of 0.5-20°, providing underlying elasticity and enabling customizable visual backgrounds.

[0076] The textured layer employs a solvent-free UV resin system, comprising 2-90 parts by weight of UV resin, 0.05-0.2 parts by weight of photoinitiator, and one or more functional additives selected from matting powder, fluff powder, PP staple fiber, and silicone microspheres. The gloss is adjusted by controlling the amount of matting powder added between 0-2 parts by weight, and fluff powder, PP staple fiber, and silicone microspheres are used to impart a delicate, soft touch, a rough, hair-like feel, and a smooth feel to the surface, respectively.

[0077] The manufacturing method of this application includes: first, preparing a matte elastic layer coating liquid and coating it onto a substrate, controlling the coating amount to be 1-10 g / m², and drying it at 50-80℃ to form a matte elastic layer; then, preparing a leather texture layer coating liquid and coating it onto the matte elastic layer, controlling the coating amount to be 3-8 g / m², pressing it with a chrome-plated steel roller, and then instantaneously curing it under UV light irradiation at 300-500 MJ / cm² to form a leather texture layer with clear outlines; finally, forming a hot melt adhesive layer on the other side of the substrate by melt extrusion.

[0078] This technical solution achieves a comprehensive improvement in visual hierarchy, tactile diversity, and texture clarity of the leather-textured pre-coated film through the synergistic design of the matte elastic layer and the leather texture layer, combined with specific material formulations and process parameters. It also features high production efficiency and good environmental performance.

[0079] The above is only one specific implementation of this application, and any other improvements made based on the concept of this application shall be considered within the scope of protection of this application.

Claims

1. A textured pre-coated film, characterized in that, It includes a hot melt adhesive layer, a substrate layer, a matte elastic layer, and a textured layer, which are stacked in sequence. The material forming the matte elastic layer includes matte waterborne polyurethane, wherein the matte waterborne polyurethane is a self-matting resin; The materials forming the textured layer include UV resin, photoinitiator, and functional additives, wherein the functional additives are selected from one or more of the following materials: matting powder, fluff powder, PP short fiber, and organosilicon microspheres.

2. The textured pre-coated film according to claim 1, characterized in that, The materials forming the matte elastic layer, by weight, include: 1-90 parts of matte waterborne polyurethane, 0.02-0.1 parts of curing agent, and 0-10 parts of high-gloss waterborne polyurethane; the materials forming the textured layer, by weight, include: 2-90 parts of UV resin, 0.05-0.2 parts of photoinitiator, 0-2 parts of matting powder, 0-1 part of fluff powder, 0-1 part of PP short fiber, and 0-1 part of silicone microspheres.

3. The textured pre-coated film according to claim 1, characterized in that, The matte waterborne polyurethane has an elongation at break of >400%, and the particle size of the microparticles in the matte waterborne polyurethane is in the range of 500nm-2000nm.

4. The textured pre-coated film according to claim 1, characterized in that, The gloss level of the matte elastic layer is in the range of 0.5°-20°.

5. The textured pre-coated film according to claim 1, characterized in that, The gloss difference between the matte elastic layer and the textured layer is in the range of 3°-15°.

6. The textured pre-coated film according to claim 1, characterized in that, The material of the substrate is selected from one or more of the following materials: PET, BOPP, CPP, PA, PVC or PC, and the thickness of the substrate layer is in the range of 12μm-100μm.

7. The leather-textured pre-coated film according to claim 1, characterized in that, The thickness of the matte elastic layer is in the range of 3μm-10μm.

8. A method for preparing a textured pre-coated film, characterized in that, include: To prepare a matte elastic layer coating liquid, a matte waterborne polyurethane emulsion and a curing agent are mixed evenly, wherein the matte waterborne polyurethane is a self-matting resin. To prepare the leather texture coating solution, UV resin, photoinitiator and functional additives are mixed evenly, wherein the functional additives are selected from one or more of the following materials: matting powder, fluff powder, PP short fiber, and organosilicon microspheres. The matte elastic layer coating liquid is applied to the substrate layer and cured to form a matte elastic layer on the substrate layer. The texture coating liquid is applied to the matte elastic layer to press out a pattern and then cured to form a texture layer on the matte elastic layer.

9. The method for preparing a textured pre-coated film according to claim 8, characterized in that, A hot melt adhesive layer is also formed on the side of the substrate layer opposite to the matte elastic layer by a coating process.

10. The method for preparing a textured pre-coated film according to claim 8, characterized in that, The particle size of the matte waterborne polyurethane is in the range of 500nm-2000nm, and a high-gloss waterborne polyurethane emulsion is also added to the matte elastic layer coating liquid.

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