Water-based back coating agent, full-water-based decorative film and preparation method of decorative film

Abstract

The invention discloses a water-based back coating agent, a full-water-based decorative film and a decorative film preparation method, and belongs to the technical field of decorative films, the water-based back coating agent comprises water-based polyurethane resin and a first initiator; the water-based polyurethane resin comprises water-based polycarbonate type polyurethane resin and acrylic acid modified water-based polyurethane resin. According to the water-based back coating agent disclosed by the invention, the acrylic acid modified water-based polyurethane resin with relatively low raw material cost is used for replacing part of water-based polycarbonate type polyurethane resin in the water-based back coating agent, so that the water-based back coating layer has good high-temperature resistance and low-temperature resistance; and the bonding strength of the water-based back coating on the surface of an attached object and a base film can be ensured not to be weakened, so that the water-based back coating has strong adhesive force on the surface of the attached object and the base film, is not easy to deglue, has good adaptability under various high-temperature and low-temperature conditions and long-time use, and has good application prospects. And an enterprise can popularize related products of the all-water-based decorative film at a relatively low price.

Description

Technical Field

[0001] The present invention relates to the technical field of decorative films, and in particular to a water-based back coating agent, a fully water-based decorative film and a method for preparing the decorative film. Background Art

[0002] Decorative film is a thin film material used to decorate and protect the surface of objects. It usually has multiple functions and characteristics and can be widely used in many fields such as construction, automobiles, and homes. With the advancement of the national environmental protection strategy and the increasing demand for green and environmentally friendly products, the environmental protection characteristics of decorative film are increasingly valued. However, existing decorative film products, whether it is the protective layer on the surface of the decorative film, the ink printing layer, or the back coating at the bottom of the decorative film, are all produced and processed using oily raw materials. Oily raw materials contain large amounts of solvents such as esters and ketones, and have high VOC (volatile organic compound) emissions, which will lead to a harsh production environment. In addition, decorative film products have a strong odor and are not environmentally friendly.

[0003] Therefore, developing fully water-based decorative film materials has become a research and development priority for decorative film manufacturers. For example, Chinese patent publication CN106978055A discloses a water-based back-coat for PVC film that resists high-temperature tack. The back coating formed by this water-based back-coat not only exhibits excellent bonding strength with the PVC film but also resists high-temperature tack. However, the high cost of the polycarbonate-based waterborne polyurethane dispersion in this water-based back-coat makes the fully water-based decorative film more expensive than conventional decorative films, hindering the promotion of related products.

[0004] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the Invention

[0005] The purpose of the present invention is to provide a water-based back coating agent, a fully water-based decorative film and a method for preparing the decorative film, aiming to solve the problem of high cost of existing water-based back coating agents.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A water-based back coating agent, comprising the following components in parts by weight:

[0008] 45-64 parts of water, 30-40 parts of waterborne polyurethane resin, 5-10 parts of matting agent, 1-5 parts of thickener, and 0.5-2 parts of first initiator; the waterborne polyurethane resin includes waterborne polycarbonate polyurethane resin and acrylic acid modified waterborne polyurethane resin.

[0009] Optionally, the waterborne polycarbonate polyurethane resin and the acrylic acid modified waterborne polyurethane resin are mixed in a weight ratio of (3-6):1.

[0010] The present invention also provides a fully aqueous decorative film, which comprises, from bottom to top, an aqueous back coating layer, a printing substrate layer, an aqueous ink printing layer, a transparent substrate layer and a protective layer; the aqueous back coating layer is formed by the aqueous back coating agent.

[0011] Optionally, the raw materials for preparing the water-based ink printing layer include the following components in parts by weight:

[0012] 61-73 parts of water, 18-24 parts of silicone-modified waterborne polyurethane resin, 8-10 parts of pigment, and 1-5 parts of wetting agent.

[0013] Optionally, the raw materials for preparing the protective layer include the following components in parts by weight:

[0014] 90-95 parts of acrylic modified waterborne polyurethane resin, 3-6 parts of polycarbodiimide, 4-6 parts of hydrophilic aliphatic polyisocyanate, 5-10 parts of diluent, 0.5-5 parts of second initiator, 0.1-1 part of defoaming agent, 0.1-1 part of wetting agent, 0.1-0.5 part of pH adjuster, and 0.01-0.05 part of bactericide.

[0015] Optionally, the matting agent comprises fumed alumina. The first initiator and the second initiator both comprise at least one of ammonium persulfate or potassium persulfate.

[0016] Optionally, the printed substrate layer includes a printed PVC layer or a printed PP layer; and the transparent substrate layer includes a transparent PVC layer or a transparent PP layer.

[0017] like Figure 1 As shown, the present invention also provides a method for preparing the all-water-based decorative film, comprising the following steps:

[0018] S001. Obtaining a protective layer on the upper surface of the transparent substrate layer;

[0019] S002. The printed substrate layer is corona treated;

[0020] S003 obtains a water-based ink printing layer on the upper surface of the printed substrate layer;

[0021] S004. The aqueous back coating agent is transferred to the lower surface of the printed substrate layer, and the aqueous back coating agent is cured to form an aqueous back coating layer;

[0022] S005. Compounding the transparent substrate layer on the water-based ink printing layer to obtain a fully water-based decorative film.

[0023] Optionally, step S001 includes:

[0024] Mixing various raw materials of the protective layer uniformly to obtain a water-based surface treatment agent;

[0025] Using a ceramic roller to transfer the aqueous surface treatment agent to the upper surface of the transparent substrate layer, and subjecting the aqueous surface treatment agent to a curing treatment to form a protective layer;

[0026] Wherein, the mesh number of the ceramic roller is 200-260 meshes.

[0027] Optionally, the viscosity of the water-based surface treatment agent is 35-40s in a Caien 3# cup.

[0028] The beneficial effects of the present invention are as follows: the present invention provides a fully aqueous decorative film and an aqueous back coating agent compatible with the fully aqueous decorative film. By using an acrylic modified aqueous polyurethane resin with relatively low raw material cost to replace part of the aqueous polycarbonate polyurethane resin in the aqueous back coating agent, the material cost of the aqueous back coating agent can be reduced. While making the aqueous back coating layer have good high and low temperature resistance, it can also ensure that the bonding strength of the aqueous back coating layer to the surface of the attached object and the base film will not be weakened, so that the aqueous back coating layer has strong adhesion to the surface of the attached object and the base film and is not easy to debond. The aqueous back coating layer has good adaptability under various high and low temperature conditions and long-term use, which is beneficial for enterprises to promote related products of the fully aqueous decorative film at a relatively low price.

[0029] By developing and designing water-based back coating, water-based ink and water-based protective layer materials, the present invention greatly reduces the emission of volatile organic compounds (VOCs) compared to traditional oil-based back coating, oil-based ink and oil-based protective layer materials. This not only improves the production environment of decorative films, but also reduces the odor of decorative films, creating a healthier use environment for users.

[0030] The present invention provides a method for preparing a fully water-based decorative film, in which water-based materials are used throughout the process to obtain a protective layer, an ink printing layer, and a water-based back coating layer on a transparent substrate layer and a printed substrate layer, thereby greatly reducing the emission of volatile organic compounds, being environmentally friendly, and complying with the concept of green production. Furthermore, the method can reduce the odor of the decorative film, creating a healthier use environment for users. Furthermore, by combining a corona treatment process, the bonding ability between the printed substrate layer and the water-based ink printing layer and the water-based back coating layer is enhanced, thereby ensuring that each layer is firmly composited, thereby improving the quality and production effect of the water-based decorative film product as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention provides a flow chart of the method for preparing the fully aqueous decorative film.

[0032] Figure 2 It is a schematic diagram of the layered structure of the all-water-based decorative film provided by the present invention.

[0033] Figure 3This is a photograph of the surface of the fully aqueous decorative film provided in Example 1.

[0034] Figure 4 This is a photograph of the surface of the all-water-based decorative film provided in Comparative Example 7.

[0035] Figure 5 This is a photograph of the surface of the all-water-based decorative film provided in Comparative Example 8. DETAILED DESCRIPTION

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

[0037] The present invention provides a water-based back coating agent, which comprises the following components in parts by weight:

[0038] 45-64 parts of water, 30-40 parts of waterborne polyurethane resin, 5-10 parts of matting agent, 1-5 parts of thickener, and 0.5-2 parts of first initiator.

[0039] The waterborne polyurethane resin includes a waterborne polycarbonate polyurethane resin and an acrylic acid-modified waterborne polyurethane resin. Specifically, the waterborne polycarbonate polyurethane resin is the commercially available Stahl PU-3408 waterborne polycarbonate polyurethane resin, and the acrylic acid-modified waterborne polyurethane resin is the commercially available BASF Joncryl-HYB6336 acrylic acid-modified waterborne polyurethane resin.

[0040] Wherein, the soft segment of the waterborne polycarbonate polyurethane resin is composed of polycarbonate polyol, and the carbonate group on its molecular chain is chemically stable and is not prone to chemical bond breakage and degradation at high temperatures. Therefore, the waterborne polycarbonate polyurethane resin has good high temperature resistance, which can make the waterborne back coating formed by the waterborne back coating agent have the ability to resist high temperatures. The acrylic acid modified waterborne polyurethane resin has carbon-carbon double bonds. Under the action of the first initiator, the carbon-carbon double bonds can form a highly cross-linked network structure, and this cross-linked structure can enhance the chemical resistance and aging resistance of the acrylic acid modified waterborne polyurethane resin, thereby improving the weather resistance of the waterborne back coating. In addition, the carbamate group (-NHCOO-) in the acrylic acid modified polyurethane resin can form hydrogen bonds, van der Waals forces, and other forces with polar groups or atoms on the surface of the attached object, thereby increasing the adhesion of the waterborne back coating to the surface of the attached object and the base film. Therefore, the present invention uses acrylic modified water-based polyurethane resin with relatively low raw material cost to replace part of the water-based polycarbonate polyurethane resin. While making the water-based back coating layer have good high-temperature and low-temperature resistance, it can also ensure that the bonding strength of the water-based back coating layer to the surface of the attached object and the base film will not be weakened, so that the water-based back coating layer has strong adhesion to the surface of the attached object and the base film and is not easy to debond. The water-based back coating layer has good adaptability under various high and low temperature conditions and long-term use, which is conducive to enterprises promoting related products of all-water decorative films at relatively low prices.

[0041] Among them, water is the main solvent of the water-based back coating agent. Compared with traditional organic solvents, water does not contain toxic and harmful volatile organic compounds, and will not cause harm to the environment and human health during production, construction and use. The matting agent, fumed alumina (Al2O3), has a high specific surface area and can enhance the wear resistance and surface tension of the water-based back coating, thereby protecting the water-based back coating and increasing the adhesion between the water-based back coating and the adhered object, extending the service life of the decorative film. In addition, fumed alumina has excellent temperature resistance and can meet the high-temperature bonding requirements during the production of water-based decorative films and various customer application conditions. The thickener can improve the film-forming properties of the water-based back coating material, allowing the water-based back coating to form a more dense and uniform film structure during the curing and drying process, thereby improving the strength and adhesion of the water-based back coating.

[0042] Optionally, the waterborne polycarbonate polyurethane resin and the acrylic acid modified waterborne polyurethane resin are mixed in a ratio of (3 to 6) parts by weight to 1. When the amount of the waterborne polycarbonate polyurethane resin used accounts for a relatively large proportion of the total polyurethane resin weight, although the waterborne back coating layer formed by the waterborne back coating agent can have the ability to resist high temperatures, the raw material cost is relatively high. When the amount of the waterborne polycarbonate polyurethane resin used accounts for a relatively small proportion of the total polyurethane resin weight, although the raw material cost can be reduced, the high temperature resistance of the waterborne back coating layer will be weakened. Therefore, the present invention controls the ratio of the waterborne polycarbonate polyurethane resin and the acrylic acid modified waterborne polyurethane resin in parts by weight within the above range, which can minimize the raw material cost while ensuring the performance of the waterborne back coating layer.

[0043] The present invention also provides a fully aqueous decorative film, such as Figure 2 As shown, the all-water-based decorative film comprises, from bottom to top, a water-based back coating layer 1, a printing substrate layer 2, a water-based ink printing layer 3, a transparent substrate layer 4, and a protective layer 5. The protective layer, as the outermost layer of the all-water-based decorative film, further enhances the film's surface resistance to wear, scratching, and weathering, thereby increasing its service life. The transparent substrate layer protects the water-based ink printing layer from external factors such as scratching, abrasion, and chemical corrosion. It also increases the transparency and gloss of the water-based decorative film, allowing the patterns and colors of the printed layer to appear more clearly and vividly, enhancing the overall aesthetics of the water-based decorative film. The water-based ink printing layer is the core layer that realizes the functions of the water-based decorative film. By printing a variety of colors and patterns, it imparts a rich and diverse appearance to the decorative film, satisfying the aesthetic and decorative needs of different users. The printing substrate layer is the base material that supports the water-based ink printing layer, providing a surface for the water-based ink to adhere to, allowing the printed patterns and text to appear clearly and firmly. The water-based back coating layer is formed by the aforementioned water-based back coating agent, which plays a role in tightly bonding with the surface of the attached object, ensuring that the fully water-based decorative film can be firmly attached to the attached object. At the same time, the water-based back coating layer can also play a certain protective role for the printed substrate layer, preventing the printed substrate layer from being damaged by external factors.

[0044] The present invention uses acrylic modified waterborne polyurethane resin with lower raw material cost to replace part of the waterborne polycarbonate polyurethane resin, thereby reducing raw material costs while ensuring the performance of the waterborne back coating layer, which is conducive to enterprises promoting related products of all-waterborne decorative films at relatively low prices.

[0045] Furthermore, the water-based ink printing layer comprises the following components by weight: 61-73 parts water, 18-24 parts organosilicon-modified waterborne polyurethane resin, 8-10 parts pigment, and 1-5 parts wetting agent. The organosilicon-modified waterborne polyurethane resin is a commercially available Dolphin 1087R3 organosilicon-modified waterborne polyurethane dispersion.

[0046] Water, as a solvent, allows the silicone-modified polyurethane resin and pigment to mix evenly, forming an ink system with excellent fluidity. Adjusting the amount of water added controls the concentration and viscosity of the water-based ink, making it suitable for the printing equipment and processes used for water-based decorative films. The wetting agent also modifies the rheological properties of the water-based ink, ensuring good transferability and ensuring the clarity of the pattern printed on the water-based ink layer. The organosilicon-modified waterborne polyurethane resin comprises an organosilicon chain segment and a polyurethane main chain, wherein the polyurethane main chain segment contains a large number of polar groups such as carbamate groups (-NHCOO-). These polar groups can interact with polar groups on the surface of the transparent substrate layer and the printing substrate layer through hydrogen bonds, van der Waals forces, etc., so that the water-based ink is firmly attached to the transparent substrate layer and the printing substrate layer, and the water-based ink printing layer has high bonding strength to the transparent substrate layer and the printing substrate layer. The organosilicon chain segment can significantly reduce the surface tension of the water-based ink, making it easier for the water-based ink to spread on the surface of the printing substrate layer during the printing process, thereby improving the wettability and adhesion of the water-based ink to the printing substrate layer, ensuring that the water-based ink can evenly cover the surface of the printing substrate layer, and forming a flat, smooth, and clear water-based ink printing layer.

[0047] Furthermore, the protective layer comprises the following components in parts by weight: 90-95 parts of an acrylic acid-modified waterborne polyurethane resin, 3-6 parts of polycarbodiimide, 4-6 parts of a hydrophilic aliphatic polyisocyanate, 5-10 parts of a diluent, 0.5-5 parts of a second initiator, 0.1-1 parts of a defoaming agent, 0.1-1 parts of a wetting agent, 0.1-0.5 parts of a pH adjuster, and 0.01-0.05 parts of a fungicide. The acrylic acid-modified waterborne polyurethane resin is commercially available from BASF, Joncryl-HYB6336 acrylic acid-modified waterborne polyurethane resin.

[0048] The acrylic modified waterborne polyurethane resin provides the basic film-forming properties of the protective layer. The polyurethane portion imparts excellent flexibility, wear resistance, and chemical resistance to the protective layer, while the acrylic resin portion enhances the hardness and weather resistance of the protective layer, making it more resistant to environmental erosion and effectively protecting the layers beneath the decorative film protective layer. The hydrophilic aliphatic isocyanate, acting as a crosslinking agent, can undergo a crosslinking reaction with the acrylic modified waterborne polyurethane resin, increasing the polymer's degree of crosslinking, thereby imparting excellent wear resistance to the protective layer. Furthermore, the hydrophilic aliphatic isocyanate imparts excellent water resistance and yellowing resistance to the protective layer, making the decorative film less susceptible to yellowing in humid environments or during long-term use. The polycarbodiimide, acting as a crosslinking agent, can undergo a crosslinking reaction with the acrylic modified waterborne polyurethane resin and synergistically act with the hydrophilic aliphatic isocyanate to further increase the polymer's degree of crosslinking, significantly improving the wear resistance of the protective layer.

[0049] The present invention develops and designs water-based back coating, water-based ink and water-based protective layer materials, which greatly reduces the emission of volatile organic compounds (VOCs) compared with traditional oil-based back coating, oil-based ink and oil-based protective layer materials. The emission of volatile organic compounds can be reduced to 1.47mg / m 3 It complies with the maximum allowable emission concentration requirements specified in the standard "DB44 / 815-2010 Printing Industry Volatile Organic Compound Emission Standard", which can not only improve the production environment of decorative film, but also reduce the odor of decorative film, creating a healthier environment for users.

[0050] Optionally, the printed substrate layer includes a printed PVC layer or a printed PP layer; the transparent substrate layer includes a transparent PVC layer or a transparent PP layer, so that the fully aqueous decorative film can not only use PVC film as the base film, but also use other types of film materials as the base film of the aqueous decorative film, thereby meeting diverse market demands.

[0051] like Figure 1 As shown, the present invention also provides a method for preparing the all-water-based decorative film, comprising the following steps:

[0052] S001. An acrylic modified waterborne polyurethane resin, polycarbodiimide, a hydrophilic aliphatic polyisocyanate, a defoamer, a wetting agent, a pH adjuster, a fungicide, a diluent, and a second initiator are uniformly mixed to obtain a waterborne surface treatment agent. The waterborne surface treatment agent is transferred to the upper surface of the transparent substrate layer using a ceramic roller and dried at 55 to 70° C. to cure the waterborne surface treatment agent to form a protective layer.

[0053] In this step, if the drying and curing temperature of the water-based surface treatment agent is too low, the water in the water-based surface treatment agent cannot fully volatilize, forming tiny pores and defects inside the protective layer, reducing the density of the protective layer and reducing the waterproof and moisture-proof capabilities of the decorative film. In addition, if the drying and curing temperature is too low, the cross-linking reaction between the polycarbodiimide and the hydrophilic aliphatic polyisocyanate and the acrylic modified waterborne polyurethane resin is incomplete, resulting in poor wear resistance of the protective layer and poor bonding strength of the protective layer to the transparent substrate layer. If the drying temperature of the water-based surface treatment agent is too high, the shrinkage rate of the protective layer will increase, affecting the dimensional stability of the decorative film.

[0054] S002. Perform corona treatment on the printed substrate layer to make the surface tension of the printed substrate layer ≥

[0055] 38dyn / cm, to prevent the surface tension of the printing substrate from being too low, so that the water-based ink can spread and adhere evenly when transferred to the surface of the printing substrate, ensuring clear printing of the water-based ink printing layer;

[0056] S003. The water, the silicone-modified waterborne polyurethane resin, the pigment and the wetting agent are mixed to obtain a water-based ink; the water-based ink is transferred to the upper surface of the printing substrate layer using a gravure printing plate roller, and dried at 55 to 70 ° C to cure the water-based ink to form a water-based ink printing layer;

[0057] In this step, if the drying and curing temperature of the water-based ink is too low, the water-based ink cannot be fully cured, and the chemical bonding and physical adsorption between the water-based ink and the printed substrate layer cannot be effectively formed, resulting in insufficient adhesion between the water-based ink and the printed substrate layer. During the subsequent processing, transportation or use of the decorative film, the water-based ink printed layer is prone to peeling and falling off, affecting the quality and service life of the decorative film product; and if the drying and curing temperature of the water-based ink is too high, it is easy to cause the pigment in the water-based ink to undergo chemical reactions such as thermal decomposition and oxidation, resulting in changes in the ink color, and the expected printing color effect cannot be achieved, affecting the visual quality of the decorative film product.

[0058] S004. The water, the waterborne polycarbonate polyurethane resin, the acrylic modified waterborne polyurethane resin, the matting agent, the thickener and the first initiator are mixed to obtain a waterborne back coating agent; the waterborne back coating agent is transferred to the lower surface of the printed substrate layer using a ceramic roller, and dried at 55 to 70 ° C to cure the waterborne back coating agent to form a waterborne back coating layer;

[0059] In this step, when the drying and curing temperature of the water-based back coating agent is too low, the water and solvent in the water-based back coating agent cannot fully evaporate, and the residual solvent will weaken the cohesion of the water-based back coating layer, reduce the strength and durability of the water-based back coating layer, and the water-based back coating is not completely cured, which will make the mechanical properties of the water-based back coating layer such as hardness and flexibility fail to meet the expected requirements.

[0060] S005. Use a laminating machine to laminate the transparent substrate layer onto the water-based ink printing layer to obtain a fully water-based decorative film.

[0061] The present invention provides a method for preparing a fully water-based decorative film, in which water-based materials are used throughout the process to obtain a protective layer, an ink printing layer, and a water-based back coating layer on a transparent substrate layer and a printed substrate layer, thereby greatly reducing the emission of volatile organic compounds, being environmentally friendly, and complying with the concept of green production. Furthermore, the method can reduce the odor of the decorative film, creating a healthier use environment for users. Furthermore, by combining a corona treatment process, the bonding ability between the printed substrate layer and the water-based ink printing layer and the water-based back coating layer is enhanced, thereby ensuring that each layer is firmly composited, thereby improving the quality and production effect of the water-based decorative film product as a whole.

[0062] Optionally, in step S001, the mesh size of the ceramic roller is 200 to 260. The mesh size of the ceramic roller reflects the number of openings per unit area on the surface of the ceramic roller. When the mesh size of the ceramic roller is greater than 260, the amount of water-based surface treatment agent transferred to the transparent substrate layer by the ceramic roller is small, and the scratch and wear resistance of the surface of the water-based decorative film, i.e., the protective layer, is poor. When the mesh size of the ceramic roller is less than 200, the water-based surface treatment agent is distributed on the surface of the transparent substrate layer as relatively large droplets, making it difficult to spread evenly, resulting in large undulations on the surface of the protective layer and the inability to form a smooth and delicate surface. Therefore, in step S002, by controlling the mesh size of the ceramic roller to 200 to 260, the surface appearance of the protective layer can be ensured to be delicate and the wear resistance of the protective layer can be improved.

[0063] Optionally, in step S001, the viscosity of the aqueous surface treatment agent is 35-40s (Zai En 3# cup). When the viscosity of the aqueous surface treatment agent is too high, it is not conducive to the transfer of the aqueous surface treatment agent to the transparent substrate layer, resulting in the accumulation of the aqueous surface treatment agent on the ceramic roller, causing granular appearance defects on the surface of the aqueous decorative film, i.e., the surface of the protective layer. When the viscosity of the aqueous surface treatment agent is too low, the fluidity of the aqueous surface treatment agent is too high, causing obvious reticulation on the surface of the aqueous decorative film. Therefore, in step S001, the viscosity of the aqueous surface treatment agent is adjusted by using a diluent (the diluent can be ethanol) to control the viscosity of the aqueous surface treatment agent to 35-40s (Zai En 3# cup), which can ensure that the surface of the protective layer does not produce obvious reticulation and appearance defects.

[0064] In order to ensure good fluidity of the water-based ink and to ensure good transfer to the printing substrate layer, optionally, in step S004, the viscosity of the water-based ink is controlled at 20 to 30 seconds per Caien 3# cup, thereby avoiding the appearance of coarse reticulation in the water-based ink printing layer and ensuring a clear pattern on the water-based ink printing layer.

[0065] Optionally, in step S003, the mesh depth of the gravure printing plate roller is 15 to 25 μm. If the mesh depth of the gravure printing plate roller is too shallow, the amount of water-based ink transferred to the printing substrate layer will be too small, resulting in low saturation of the printed pattern. If the mesh depth is too deep, the water-based ink will not be transferred in time and will easily clog the mesh. This will not only cause inconvenience in cleaning the gravure printing plate roller, but also cause defects in the appearance of the water-based ink layer. Therefore, to avoid the above problems, in step S005, it is preferred to use a gravure printing plate roller with a mesh depth of 15 to 25 μm.

[0066] Optionally, in step S004, the viscosity of the water-based back coating agent is 32 to 38 seconds per Cai En 3# cup. When the viscosity of the water-based back coating agent is low, the amount of the water-based back coating agent transferred to the printing substrate layer is relatively small, resulting in insufficient thickness of the water-based back coating layer, and unable to provide sufficient bonding strength between the printing substrate layer and the surface of the adhered object; and when the viscosity of the water-based back coating agent is high, it is not conducive to the transfer of the water-based back coating agent to the printing substrate layer, and it is easy to cause granular appearance defects on the surface of the printing substrate layer. Therefore, in order to enable the water-based back coating layer to provide sufficient bonding strength to both the printing substrate layer and the surface of the adhered object, in step S006, the viscosity of the water-based back coating is controlled at 32 to 38 seconds per Cai En 3# cup.

[0067] Optionally, in order to ensure that the amount of water-based back coating transferred to the printed substrate layer is sufficient, to ensure that the water-based back coating layer can provide sufficient bonding strength to both the printed substrate layer and the surface of the adhered object, and that the water-based back coating layer does not have obvious appearance defects, in step S004, the mesh size of the ceramic roller is 200 to 260 meshes.

[0068] In order to further illustrate the fully aqueous decorative film and preparation method provided by the present invention, the following examples and comparative examples are provided.

[0069] Example 1

[0070] This embodiment provides a fully aqueous decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer;

[0071] The water-based back coating layer is formed by curing a water-based back coating agent, and the raw materials for preparing the water-based back coating agent are composed of the following raw materials in parts by weight: 45 parts of water, 25 parts of water-based polycarbonate polyurethane resin, 5 parts of acrylic acid-modified water-based polyurethane resin, 5 parts of fumed alumina, 1 part of thickener, and 1 part of ammonium persulfate (first initiator); among the raw materials for preparing the water-based back coating agent, the water-based polycarbonate polyurethane resin is the commercially available Stahl PU-3408 water-based polycarbonate polyurethane resin; the acrylic acid-modified water-based polyurethane resin is the commercially available BASF Joncryl-HYB6336 acrylic acid-modified water-based polyurethane resin;

[0072] The raw materials for preparing the water-based ink printing layer are composed of the following raw materials in parts by weight: 61 parts of water, 18 parts of organosilicon-modified waterborne polyurethane resin, 8 parts of pigment, and 1 part of wetting agent; the organosilicon-modified waterborne polyurethane resin is commercially available Dolphin 1087R3 organosilicon-modified waterborne polyurethane dispersion;

[0073] The raw materials for preparing the protective layer are composed of the following raw materials in parts by weight: 90 parts of acrylic acid-modified waterborne polyurethane resin, 3 parts of polycarbodiimide, 4 parts of hydrophilic aliphatic polyisocyanate, 5 parts of diluent, 2.5 parts of ammonium persulfate (second initiator), 0.1 part of defoamer, 0.1 part of wetting agent, 0.1 part of pH adjuster, and 0.01 part of bactericide; among the raw materials for preparing the protective layer, the acrylic acid-modified waterborne polyurethane resin is commercially available BASF Joncryl-HYB6336 acrylic acid-modified waterborne polyurethane resin.

[0074] This embodiment also provides a method for preparing a fully aqueous decorative film, comprising the following steps:

[0075] S001 The acrylic modified waterborne polyurethane resin, polycarbodiimide, hydrophilic aliphatic polyisocyanate, defoamer, wetting agent, pH adjuster, bactericide, diluent and ammonium persulfate were mixed to obtain a water-based surface treatment agent, the viscosity of the water-based surface treatment agent is Cai En 3 # cup 35s;

[0076] The water-based surface treatment agent is transferred to the upper surface of the transparent substrate layer using a 200-mesh ceramic roller, and dried at 55-70° C. to solidify the water-based surface treatment agent to form a protective layer;

[0077] S002. The printed substrate layer is corona treated to make the surface tension of the printed substrate layer ≥38dyn / cm;

[0078] S003 water, silicone modified waterborne polyurethane resin, pigment and wetting agent are mixed to obtain a water-based ink, the viscosity of the water-based ink is Cai En 3 # cup 25s;

[0079] The water-based ink is transferred to the upper surface of the printing substrate layer using a gravure printing plate roller with a mesh depth of 20 μm, and dried at 55 to 70° C. to solidify the water-based ink to form a water-based ink printing layer;

[0080] S004 water, waterborne polycarbonate polyurethane resin, acrylic modified waterborne polyurethane resin, matting agent, thickener and ammonium persulfate were mixed to obtain a waterborne back coating agent, the viscosity of the waterborne back coating agent is Cai En 3 # cup 35s;

[0081] The water-based back coating is transferred to the lower surface of the printing substrate layer using a 220-mesh ceramic roller, and dried at 55-70° C. to solidify the water-based back coating to form a water-based back coating layer;

[0082] S005. Use a laminating machine to laminate the transparent substrate layer onto the water-based ink printing layer to obtain a fully water-based decorative film.

[0083] Example 2

[0084] This embodiment provides a fully aqueous decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer;

[0085] The water-based back coating layer is formed by curing a water-based back coating agent, and the raw materials for preparing the water-based back coating agent are composed of the following raw materials in parts by weight: 50 parts of water, 27 parts of water-based polycarbonate polyurethane resin, 8 parts of acrylic acid-modified water-based polyurethane resin, 7 parts of fumed alumina, 3 parts of thickener, and 1 part of potassium persulfate (first initiator); among the raw materials for preparing the water-based back coating agent, the water-based polycarbonate polyurethane resin is the commercially available Stahl PU-3408 water-based polycarbonate polyurethane resin; the acrylic acid-modified water-based polyurethane resin is the commercially available BASF Joncryl-HYB6336 acrylic acid-modified water-based polyurethane resin;

[0086] The raw materials for preparing the water-based ink printing layer are composed of the following raw materials in parts by weight: 70 parts of water, 20 parts of organosilicon-modified waterborne polyurethane resin, 9 parts of pigment, and 3 parts of wetting agent; the organosilicon-modified waterborne polyurethane resin is commercially available Dolphin 1087R3 organosilicon-modified waterborne polyurethane dispersion;

[0087] The raw materials for preparing the protective layer are composed of the following raw materials in parts by weight: 92 parts of acrylic acid-modified waterborne polyurethane resin, 5 parts of polycarbodiimide, 5 parts of hydrophilic aliphatic polyisocyanate, 7 parts of diluent, 2.5 parts of potassium persulfate (second initiator), 0.5 parts of defoaming agent, 0.5 parts of wetting agent, 0.3 parts of pH regulator, and 0.03 parts of bactericide; among the raw materials for preparing the protective layer, the acrylic acid-modified waterborne polyurethane resin is commercially available BASF Joncryl-HYB6336 acrylic acid-modified waterborne polyurethane resin.

[0088] This embodiment also provides a method for preparing a fully aqueous decorative film, wherein steps S002 to S005 are the same as those in Example 1; step S001 differs from Example 1 in that the viscosity of the aqueous surface treatment agent is 38s per Caien 3# cup; and the mesh size of the ceramic roller is 260 mesh.

[0089] Example 3

[0090] This embodiment provides a fully aqueous decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer;

[0091] The water-based back coating layer is formed by curing a water-based back coating agent, and the raw materials for preparing the water-based back coating agent are composed of the following raw materials in parts by weight: 64 parts of water, 30 parts of water-based polycarbonate polyurethane resin, 10 parts of acrylic acid-modified water-based polyurethane resin, 10 parts of fumed alumina, 5 parts of thickener, and 1 part of ammonium persulfate (first initiator); among the raw materials for preparing the water-based back coating agent, the water-based polycarbonate polyurethane resin is the commercially available Stahl PU-3408 water-based polycarbonate polyurethane resin; the acrylic acid-modified water-based polyurethane resin is the commercially available BASF Joncryl-HYB6336 acrylic acid-modified water-based polyurethane resin;

[0092] The raw materials for preparing the water-based ink printing layer are composed of the following raw materials in parts by weight: 73 parts of water, 24 parts of organosilicon-modified waterborne polyurethane resin, 10 parts of pigment, and 5 parts of wetting agent; the organosilicon-modified waterborne polyurethane resin is commercially available Dolphin 1087R3 organosilicon-modified waterborne polyurethane dispersion;

[0093] The raw materials for preparing the protective layer are composed of the following raw materials in parts by weight: 95 parts of acrylic acid-modified waterborne polyurethane resin, 6 parts of polycarbodiimide, 6 parts of hydrophilic aliphatic polyisocyanate, 10 parts of diluent, 2.5 parts of ammonium persulfate (second initiator), 1 part of defoamer, 1 part of wetting agent, 0.5 part of pH adjuster, and 0.05 part of bactericide; among the raw materials for preparing the protective layer, the acrylic acid-modified waterborne polyurethane resin is commercially available BASF Joncryl-HYB6336 acrylic acid-modified waterborne polyurethane resin.

[0094] This embodiment further provides a method for preparing a fully aqueous decorative film. The method for preparing the fully aqueous decorative film provided is the same as the method for preparing the fully aqueous decorative film provided in Example 1.

[0095] Comparative Example 1

[0096] This comparative example provides a fully water-based decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer; the raw materials for preparing the protective layer are the same as those in Example 1, and the raw materials for preparing the water-based ink printing layer are the same as those in Example 1; the water-based back coating layer is formed by curing a water-based back coating agent, and the raw materials for preparing the water-based back coating agent are composed of the following raw materials in parts by weight: 45 parts of water, 40 parts of acrylic acid-modified water-based polyurethane resin, 5 parts of fumed alumina, 1 part of thickener, and 1 part of ammonium persulfate (first initiator); among the raw materials for preparing the water-based back coating agent, the acrylic acid-modified water-based polyurethane resin is the commercially available BASF Joncryl-HYB6336 acrylic acid-modified water-based polyurethane resin.

[0097] This comparative example also provides a method for preparing a fully aqueous decorative film. The method for preparing the fully aqueous decorative film provided is the same as the method for preparing the fully aqueous decorative film provided in Example 1.

[0098] Comparative Example 2

[0099] This comparative example provides a fully aqueous decorative film, which comprises, from bottom to top, an aqueous back coating layer, a printing substrate layer, an aqueous ink printing layer, a transparent substrate layer, and a protective layer. The raw materials for preparing the protective layer are the same as those in Example 1. The aqueous back coating layer is formed by curing an aqueous back coating agent. The raw materials for preparing the aqueous back coating agent are composed of the following raw materials in parts by weight: 45 parts of water, 40 parts of an aqueous polycarbonate polyurethane resin, 5 parts of fumed alumina, 1 part of a thickener, and 1 part of ammonium persulfate (a first initiator). Among the raw materials for preparing the aqueous back coating agent, the aqueous polycarbonate polyurethane resin is the commercially available Stahl PU-3408 aqueous polycarbonate polyurethane resin.

[0100] This comparative example also provides a method for preparing a fully aqueous decorative film. The method for preparing the fully aqueous decorative film provided is the same as the method for preparing the fully aqueous decorative film provided in Example 1.

[0101] Comparative Example 3

[0102] This comparative example provides a fully water-based decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer. The raw materials for preparing the protective layer are the same as those in Example 1. The water-based back coating layer is formed by curing a water-based back coating agent. The raw materials for preparing the water-based back coating agent are composed of the following raw materials in parts by weight: 64 parts of water, 15 parts of a water-based polycarbonate polyurethane resin, 15 parts of an acrylic acid-modified water-based polyurethane resin, 10 parts of fumed alumina, 5 parts of a thickener, and 1 part of ammonium persulfate (a first initiator). Among the raw materials for preparing the water-based back coating agent, the water-based polycarbonate polyurethane resin is the commercially available Stahl PU-3408 water-based polycarbonate polyurethane resin; and the acrylic acid-modified water-based polyurethane resin is the commercially available BASF Joncryl-HYB6336 acrylic acid-modified water-based polyurethane resin.

[0103] This comparative example also provides a method for preparing a fully aqueous decorative film. The method for preparing the fully aqueous decorative film provided is the same as the method for preparing the fully aqueous decorative film provided in Example 1.

[0104] Comparative Example 4

[0105] This comparative example provides a fully water-based decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer. The water-based back coating layer is formed by curing a water-based back coating agent, the raw materials for preparing the water-based back coating agent are the same as those in Example 1. The raw materials for preparing the water-based ink printing layer are the same as those in Example 1. The raw materials for preparing the protective layer are composed of the following raw materials in parts by weight: 90 parts of an acrylic acid-modified water-based polyurethane resin, 7 parts of a hydrophilic aliphatic polyisocyanate, 5 parts of a diluent, 2.5 parts of ammonium persulfate (a second initiator), 0.1 part of a defoamer, 0.1 part of a wetting agent, 0.1 part of a pH adjuster, and 0.01 part of a fungicide. Among the raw materials for preparing the protective layer, the acrylic acid-modified water-based polyurethane resin is commercially available BASF Joncryl-HYB6336 acrylic acid-modified water-based polyurethane resin.

[0106] This comparative example also provides a method for preparing a fully aqueous decorative film. The method for preparing the fully aqueous decorative film provided is the same as the method for preparing the fully aqueous decorative film provided in Example 1.

[0107] Comparative Example 5

[0108] This comparative example provides a fully water-based decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer. The water-based back coating layer is formed by curing a water-based back coating agent, the raw materials for preparing the water-based back coating agent are the same as those in Example 1. The raw materials for preparing the protective layer are the same as those in Example 1. The raw materials for preparing the water-based ink printing layer are composed of the following raw materials in parts by weight: 61 parts of water, 5 parts of an organosilicon-modified waterborne polyurethane resin, 8 parts of a pigment, and 1 part of a wetting agent. The organosilicon-modified waterborne polyurethane resin is a commercially available Dolphin 1087R3 organosilicon-modified waterborne polyurethane dispersion.

[0109] This comparative example also provides a method for preparing a fully aqueous decorative film. The method for preparing the fully aqueous decorative film provided is the same as the method for preparing the fully aqueous decorative film provided in Example 1.

[0110] Comparative Example 6

[0111] This comparative example provides a fully water-based decorative film, which comprises, from bottom to top, a water-based back coating layer, a printing substrate layer, a water-based ink printing layer, a transparent substrate layer, and a protective layer. The water-based back coating layer is formed by curing a water-based back coating agent, the raw materials for preparing the water-based back coating agent being the same as those in Example 1. The raw materials for preparing the protective layer are the same as those in Example 1. The raw materials for preparing the water-based ink printing layer are composed of the following raw materials in parts by weight: 61 parts of water, 30 parts of an organosilicon-modified waterborne polyurethane resin, 8 parts of a pigment, and 1 part of a wetting agent. The organosilicon-modified waterborne polyurethane resin is a commercially available Dolphin 1087R3 organosilicon-modified waterborne polyurethane dispersion.

[0112] This comparative example also provides a method for preparing a fully aqueous decorative film. The method for preparing the fully aqueous decorative film provided is the same as the method for preparing the fully aqueous decorative film provided in Example 1.

[0113] Comparative Example 7

[0114] This comparative example provides a fully aqueous decorative film, which includes, from bottom to top, an aqueous back coating layer, a printing substrate layer, an aqueous ink printing layer, a transparent substrate layer, and a protective layer; the aqueous back coating layer is formed by curing an aqueous back coating agent, the raw materials for preparing the aqueous back coating agent are the same as those in Example 1, the raw materials for preparing the aqueous ink printing layer are the same as those in Example 1, and the raw materials for preparing the protective layer are the same as those in Example 1.

[0115] This comparative example also provides a method for preparing a fully aqueous decorative film. The difference between the provided method for preparing a fully aqueous decorative film and the method for preparing a fully aqueous decorative film provided in Example 1 is that in step S001, the viscosity of the aqueous surface treatment agent is 30s of a Caien 3# cup.

[0116] Comparative Example 8

[0117] This comparative example provides a fully aqueous decorative film, which includes, from bottom to top, an aqueous back coating layer, a printing substrate layer, an aqueous ink printing layer, a transparent substrate layer, and a protective layer; the aqueous back coating layer is formed by curing an aqueous back coating agent, the raw materials for preparing the aqueous back coating agent are the same as those in Example 1, the raw materials for preparing the aqueous ink printing layer are the same as those in Example 1, and the raw materials for preparing the protective layer are the same as those in Example 1.

[0118] This comparative example also provides a method for preparing a fully aqueous decorative film. The difference between the method for preparing a fully aqueous decorative film provided and the method for preparing a fully aqueous decorative film provided in Example 1 is that in step S001, the mesh size of the ceramic roller is 180 meshes.

[0119] Comparative Example 9

[0120] This comparative example provides a fully aqueous decorative film, which includes, from bottom to top, an aqueous back coating layer, a printing substrate layer, an aqueous ink printing layer, a transparent substrate layer, and a protective layer; the aqueous back coating layer is formed by curing an aqueous back coating agent, the raw materials for preparing the aqueous back coating agent are the same as those in Example 1, the raw materials for preparing the aqueous ink printing layer are the same as those in Example 1, and the raw materials for preparing the protective layer are the same as those in Example 1.

[0121] This comparative example also provides a method for preparing a fully aqueous decorative film. The difference between the method for preparing a fully aqueous decorative film provided and the method for preparing a fully aqueous decorative film provided in Example 1 is that in step S001, the mesh size of the ceramic roller is 280 meshes.

[0122] According to the test method specified in the standard "GB / T 17657-2022 Test methods for physical and chemical properties of artificial boards and veneered artificial boards", the water-based back coatings of the fully water-based decorative films provided in Examples 1 to 3 and the water-based back coatings of the fully water-based decorative films provided in Comparative Examples 1 to 3 were subjected to hot and cold cycle tests. The test temperature conditions were 75°C / -20°C. The test results are shown in Table 1.

[0123] According to the test method specified in the standard "GB / T 9286-2021 Cross-cut test for paint and varnish films", the adhesion of the water-based back coating layer (paint film) of the fully water-based decorative films provided in Examples 1 to 3 to the printed substrate layer and the adhesion of the water-based back coating layer of the fully water-based decorative films provided in Comparative Examples 1 to 3 to the printed substrate layer were tested. The test results are shown in Table 1.

[0124] Table 1:

[0125] Hot and cold cycle test Water-based back coating adhesion Example 1 75℃ / -20℃, no glue peeling Level 0 Example 2 75℃ / -20℃, no glue peeling Level 0 Example 3 75℃ / -20℃, no glue peeling Level 0 Comparative Example 1 75℃ / -20℃, glue peeling Level 0 Comparative Example 2 75℃ / -20℃, slight debonding Level 1 Comparative Example 3 75℃ / -20℃, slight debonding Level 0

[0126] The test results in Table 1 show that the water-based back coating layer of the all-water-based decorative film provided in Comparative Example 1 exhibited delamination after a 75°C / -20°C hot / cold cycle test. This is because the water-based back coating in Comparative Example 1 only used an acrylic acid-modified waterborne polyurethane resin, without a waterborne polycarbonate-type polyurethane resin, which weakened the high-temperature resistance of the water-based back coating layer. The adhesion of the water-based back coating layer of the all-water-based decorative film provided in Comparative Example 2 was inferior to that of Examples 1 to 3 and Comparative Examples 1 and 3. This is because the water-based back coating in Comparative Example 2 only used a waterborne polycarbonate-type polyurethane resin, without an acrylic acid-modified waterborne polyurethane resin. This indicates that the use of an acrylic acid-modified waterborne polyurethane resin in the water-based back coating layer can improve the strength and adhesion of the water-based back coating layer. The water-based back coating layer of the all-water-based decorative film provided in Comparative Example 3 exhibited slight delamination after a 75°C / -20°C hot / cold cycle test. This is because the water-based polycarbonate-type polyurethane resin was used in a reduced proportion of the total polyurethane resin weight, which weakened the high-temperature resistance of the water-based back coating layer.

[0127] According to the standard "GB / T 8808 Test Method for Peel Strength of Plastic Composite Films," the interlayer peel strength between the transparent substrate layer and the aqueous ink layer in the fully aqueous decorative films provided in Examples 1 to 3, as well as the fully aqueous decorative films provided in Comparative Examples 5 and 6, was tested. The pattern in the ink printed layer was also visually observed. The observation and test results are shown in Table 2.

[0128] Table 2:

[0129]

[0130]

[0131] The test results in Table 2 show that the decorative film provided in Comparative Example 5 exhibits low interlayer peel strength between the aqueous ink layer and the transparent substrate layer, and the printed pattern lacks saturation. This is because the amount of organosilicon-modified waterborne polyurethane resin in the aqueous ink used in Comparative Example 5 is relatively low, resulting in low wettability and adhesion of the aqueous ink to the printed substrate layer. This results in easy peeling of the transparent substrate layer and the aqueous ink layer during testing. In contrast, the decorative film provided in Comparative Example 6 exhibits high interlayer peel strength between the aqueous ink layer and the transparent substrate layer, but the pattern on the aqueous ink printed layer lacks clarity. This is because the amount of organosilicon-modified waterborne polyurethane resin in the aqueous ink used in Comparative Example 6 increases the viscosity of the aqueous ink, resulting in poor fluidity. This makes it difficult for the aqueous ink to smoothly fill the mesh of the gravure printing roller during transfer, resulting in insufficient transfer of the aqueous ink to the printed substrate layer and a lack of clarity in the printed pattern.

[0132] Obtain Example 1 (see Figure 3 ) provides a full water-based decorative film and comparative example 7 (see Figure 4 ) and Comparative Example 8 (see Figure 5 ) provides photos of the surface of the all-water-based decorative film (i.e. the surface of the protective layer), from Figure 4 From the photos of the surface of the fully water-based decorative film provided, it can be seen that the surface of the fully water-based decorative film provided in Comparative Example 7 has obvious reticulation. This is because the viscosity of the water-based treatment agent is low and the fluidity of the water-based surface treatment agent is too high, which will cause obvious reticulation on the surface of the water-based decorative film. Figure 5 As can be seen from the photos of the surface of the all-water-based decorative film provided, the surface appearance of the all-water-based decorative film provided in Comparative Example 8 is not delicate enough. This is because the mesh size of the ceramic roller used to transfer the water-based treatment agent is small, and the water-based surface treatment agent is distributed on the surface of the transparent substrate layer in the form of relatively large droplets, which is difficult to spread evenly, resulting in large undulations on the surface of the protective layer, and the inability to form a delicate and smooth surface state.

[0133] In accordance with the provisions of the standard "GB / T 17657-2022 Test methods for physical and chemical properties of artificial boards and veneered artificial boards", the scratch resistance and wear resistance of the fully aqueous decorative film surfaces provided in Examples 1 to 3 and the fully aqueous decorative film surfaces (i.e., protective layers) provided in Comparative Examples 9 and 4 were tested, and the test results are shown in Table 3.

[0134] Table 3:

[0135] Scratch-resistant wear-resistant Example 1 1.4N 200 rpm Example 2 1.2N 150 rpm Example 3 1.4N 205 rpm Comparative Example 9 0.7N 90 rpm Comparative Example 4 0.6N 70 rpm

[0136] As can be seen from the test results in Table 3, the scratch and wear resistance data of the surface of the all-water-based decorative film provided in Comparative Example 9 are inferior to those of the all-water-based decorative films provided in Examples 1 to 3. This is because the ceramic roller used to transfer the water-based treatment agent has a larger mesh size, resulting in a small amount of water-based surface treatment agent transferred to the transparent substrate layer by the ceramic roller. The scratch and wear resistance data of the surface of the all-water-based decorative film provided in Comparative Example 4 are also inferior to those of the all-water-based decorative films provided in Examples 1 to 3. This is because Comparative Example 4 does not simultaneously use two cross-linking agents to react with the acrylic acid-modified waterborne polyurethane resin, resulting in a limited increase in the degree of cross-linking of the polymer.

[0137] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A water-based back coating agent, characterized in that: The water-based back coating agent comprises the following components in parts by weight: 45 to 64 parts of water, 30 to 40 parts of water-based polyurethane resin, 5 to 10 parts of matting agent, 1 to 5 parts of thickener, and 0.5 to 2 parts of first initiator; the water-based polyurethane resin comprises water-based polycarbonate polyurethane resin and acrylic acid-modified water-based polyurethane resin.

2. The water-based back coating agent according to claim 1, characterized in that The waterborne polycarbonate polyurethane resin and the acrylic acid modified waterborne polyurethane resin are mixed in a weight ratio of (3-6):

1.

3. A fully water-based decorative film, characterized in that: The fully aqueous decorative film comprises, from bottom to top, an aqueous back coating layer, a printing substrate layer, an aqueous ink printing layer, a transparent substrate layer and a protective layer; the aqueous back coating layer is formed by the aqueous back coating agent according to any one of claims 1-2.

4. The fully aqueous decorative film according to claim 3, characterized in that: The raw materials for preparing the water-based ink printing layer include the following components in parts by weight: 61-73 parts of water, 18-24 parts of silicone-modified waterborne polyurethane resin, 8-10 parts of pigment, and 1-5 parts of wetting agent.

5. The fully aqueous decorative film according to claim 3, characterized in that: The raw materials for preparing the protective layer include the following components in parts by weight: 90-95 parts of acrylic modified waterborne polyurethane resin, 3-6 parts of polycarbodiimide, 4-6 parts of hydrophilic aliphatic polyisocyanate, 5-10 parts of diluent, 0.5-5 parts of second initiator, 0.1-1 part of defoaming agent, 0.1-1 part of wetting agent, 0.1-0.5 part of pH adjuster, and 0.01-0.05 part of bactericide.

6. The fully aqueous decorative film according to claim 3, characterized in that: The matting agent includes fumed alumina.

7. The fully aqueous decorative film according to claim 3, characterized in that: The printed substrate layer includes a printed PVC layer or a printed PP layer; the transparent substrate layer includes a transparent PVC layer or a transparent PP layer.

8. A method for preparing a fully aqueous decorative film according to any one of claims 3 to 7, characterized in that: The following steps are involved: S001. Obtaining a protective layer on the upper surface of the transparent substrate layer; S002. The printed substrate layer is corona treated; S003 obtains a water-based ink printing layer on the upper surface of the printed substrate layer; S004. The aqueous back coating agent is transferred to the lower surface of the printed substrate layer, and the aqueous back coating agent is cured to form an aqueous back coating layer; S005. Compounding the transparent substrate layer on the water-based ink printing layer to obtain a fully water-based decorative film.

9. The method for preparing a fully aqueous decorative film according to claim 8, characterized in that: Step S001 includes: Mixing various raw materials of the protective layer uniformly to obtain a water-based surface treatment agent; Using a ceramic roller to transfer the aqueous surface treatment agent to the upper surface of the transparent substrate layer, and subjecting the aqueous surface treatment agent to a curing treatment to form a protective layer; Wherein, the mesh number of the ceramic roller is 200-260 meshes.

10. The method for preparing a fully aqueous decorative film according to claim 9, characterized in that: The viscosity of the water-based surface treatment agent is 35-40s in a Caien 3# cup.

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