A decorative base paper suitable for water-based ink printing and a method for manufacturing the same

Abstract

The application relates to the technical field of pulping and papermaking, and provides a decorative base paper suitable for water-based ink printing and a preparation method thereof. The decorative base paper comprises, from bottom to top, a main body layer, a transition layer and a functional layer. The main body layer comprises bleached chemical pulp, a wet strength agent and nanocellulose; the transition layer comprises a barrier material, a filler and an acrylic emulsion; and the functional layer comprises silicon dioxide, polyvinyl alcohol, an acrylic emulsion and a crosslinking agent. Through the synergistic effect of the three-layer structure, the problems of wetting instability, slow drying, dot diffusion and fluffing and powdering in water-based ink printing are effectively solved, meanwhile, the defect of resin impregnation being hindered due to excessive sealing of the surface is avoided, so that rapid ink absorption and clear imaging can be realized in the printing stage, and good resin permeability can be maintained in the impregnation stage, thereby the water-based ink printing adaptability and the subsequent processing performance of the decorative base paper are taken into account.

Description

Technical Field

[0001] This application relates to the field of pulp and paper technology, and in particular to a decorative base paper suitable for water-based ink printing and its preparation method. Background Technology

[0002] Decorative base paper, after resin impregnation and hot pressing, is widely used as the surface layer of decorative panels for furniture, flooring, and other decorative materials. Currently, printing primarily uses solvent-based inks, which differ significantly from water-based inks in their absorption, spreading, and drying mechanisms.

[0003] With increasingly stringent environmental protection requirements, the demand for low-VOC water-based inks is growing. However, water-based inks have high water content and surface tension, making them more sensitive to base paper. This presents multiple challenges when using water-based inks directly on existing decorative base paper: First, insufficient wet dimensional stability; during printing, the paper absorbs water and swells, causing expansion and contraction, leading to misregistration, wrinkling, and other problems. Second, it is difficult to balance ink absorption and color retention; excessive absorption can lead to dot gain and uneven coloring, while excessive inhibition of absorption can affect drying and adhesion. Third, surface energy and interface compatibility issues can easily cause poor wetting, pinholes, ink smudging, and decreased abrasion resistance. Fourth, there is a contradiction between improving printability and subsequent resin impregnation; improving printability may make the paper surface too dense, hindering uniform resin penetration and affecting the final lamination quality.

[0004] Therefore, there is an urgent need to provide a suitable decorative base paper for water-based ink printing and its preparation method to solve the above problems. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the purpose of this application is to provide a decorative base paper for water-based ink printing and a method for preparing the same.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application provide a decorative base paper suitable for water-based ink printing, comprising, from bottom to top: a main layer, a transition layer, and a functional layer. The main layer comprises bleached chemical pulp, a wet strength agent, and nanocellulose; the transition layer comprises a barrier material, a filler, and an acrylic emulsion; and the functional layer comprises silica, polyvinyl alcohol, an acrylic emulsion, and a crosslinking agent.

[0007] In one alternative implementation, the thickness of the main layer is 70-95 μm; and / or the thickness of the transition layer is 5-15 μm; and / or the thickness of the functional layer is 0.5-3 μm.

[0008] In one alternative embodiment, in the main body layer, the mass ratio of bleaching chemical pulp, wet strength agent, and nanocellulose is 1:(0.005-0.015):(0.0025-0.01); and / or in the transition layer, the mass ratio of barrier material, filler, and acrylic emulsion is (0.001-0.015):(0.8-1.5):1; and / or in the functional layer, the mass ratio of silica, polyvinyl alcohol, acrylic emulsion, and crosslinking agent is 1:(0.25-1.25):(0.75-2.75):(0.025-0.25).

[0009] In an optional embodiment, in the main body layer, the bleached chemical pulp comprises bleached softwood pulp and bleached hardwood pulp in a mass ratio of 1:(1.2-2.3); and / or in the transition layer, the barrier material comprises at least one or a combination of graphene oxide and montmorillonite.

[0010] Secondly, embodiments of this application provide a method for preparing decorative base paper suitable for water-based ink printing, used to prepare decorative base paper as described in any of the above technical solutions, the preparation method including the following steps: S100: Add wet strength agent and nanocellulose to bleached chemical pulp, form paper, and obtain the main layer; S200: A transition layer coating liquid is applied to the surface of the main layer and a first drying treatment is performed to obtain an intermediate paper layer; S300: A functional layer coating liquid is coated onto the transition layer of the intermediate paper layer and a second drying treatment is performed to obtain a decorative base paper suitable for water-based ink printing.

[0011] In an optional embodiment, the method for preparing the functional layer coating liquid includes the following steps: S310. Dissolve polyvinyl alcohol in deionized water to obtain a polyvinyl alcohol solution; S320. Add silica to a polyvinyl alcohol solution for dispersion treatment to obtain a dispersion. S330. Add acrylic emulsion to dispersion, then add crosslinking agent, and mix to obtain functional layer coating liquid.

[0012] In one alternative embodiment, the dispersion treatment is ultrasonic dispersion; and / or the dispersion treatment time is 0.5-1 h; and / or the crosslinking agent is a carbodiimide crosslinking agent.

[0013] In one alternative embodiment, the temperature of the first drying process is 105-120°C; and / or the temperature of the second drying process is 90-105°C.

[0014] In one alternative implementation, the bleached chemical pulp has a freeness of 28-38°SR.

[0015] In an optional implementation, S300 further includes: S301. Calender the decorative base paper.

[0016] The beneficial effects of this application include at least the following: (1) This application effectively solves the problems of unstable wetting, slow drying, dot diffusion and fuzzing in water-based ink printing through the synergistic effect of the three-layer structure. At the same time, it avoids the defect of excessive surface sealing leading to resin impregnation obstruction. Thus, it can achieve rapid ink absorption and clear imaging in the printing stage and maintain good resin permeability in the impregnation stage, thereby taking into account both the adaptability of water-based ink printing and the subsequent processing performance of decorative base paper. (2) The preparation method of this application constructs each layer of decorative base paper in steps and dries them separately, which is conducive to each layer playing an independent role, while ensuring strong interlayer bonding and structural stability. Detailed Implementation

[0017] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are only for explaining this application, but the implementation of this application is not limited thereto.

[0018] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.

[0019] Compared to traditional inks, water-based inks use water as the primary carrier and are characterized by high surface tension and high water content. This presents three key challenges during the printing process: first, the uniformity of ink wetting and spreading on the paper surface; second, the controllability of water absorption and pigment diffusion; and third, the dimensional stability of the paper in a wet state. Insufficient paper surface energy or an unsuitable pore structure can easily lead to problems such as pinholes, cratering, and white spots. Excessive absorption or uneven pore structure can cause pigment to diffuse laterally with the water, resulting in dot gain, uneven coloring, or decreased color density. Insufficient wet strength of the paper can cause fuzzing, powdering, and misregistration. Therefore, decorative base paper suitable for water-based ink printing must strike a balance between rapid water absorption and controlled diffusion, while also possessing good wet dimensional stability.

[0020] Decorative base paper differs from ordinary printing paper. After printing, it requires melamine resin impregnation and hot-pressing. Therefore, the paper must not only perform well during the printing stage but also maintain good resin permeability during the impregnation stage. If an overly closed or dense film-forming surface structure is used to improve the printability of water-based inks, it may cause the resin to have difficulty penetrating into the internal pores of the paper, resulting in defects such as white spots, fogging, or reduced transparency.

[0021] Therefore, this invention uses a layered structure design to allocate different functions to different levels in order to achieve a synergistic balance between printing performance and immersion performance.

[0022] In a first aspect, embodiments of this application provide a decorative base paper suitable for water-based ink printing, comprising, from bottom to top: a main layer, a transition layer, and a functional layer. The main layer comprises bleached chemical pulp, a wet strength agent, and nanocellulose; the transition layer comprises a barrier material, a filler, and an acrylic emulsion; and the functional layer comprises silica, polyvinyl alcohol, an acrylic emulsion, and a crosslinking agent.

[0023] Specifically, the decorative base paper of this application consists of a main layer, a transition layer, and a functional layer. The main layer primarily provides mechanical support and wet stability. The main layer uses bleached chemical pulp as the fiber skeleton to ensure good strength and uniform pore structure. The bleached chemical pulp includes bleached softwood pulp and bleached hardwood pulp. Softwood pulp fibers are longer, providing higher strength and tensile properties; hardwood pulp fibers are shorter, improving uniformity and surface smoothness. The mass ratio of bleached softwood pulp to bleached hardwood pulp is 1:(1.2-2.3), ensuring both strength and improving printing smoothness and pore structure uniformity, thus balancing printing and impregnation requirements. By adding a wet strength agent, a water-resistant bonding structure is formed between the fibers, maintaining high wet tensile strength and dimensional stability even when exposed to large amounts of water during water-based ink printing. PAE wet strength agent is preferred. Simultaneously, nanocellulose is introduced as a reinforcing component, which can fill fiber gaps at the microscale, enhance fiber bonding, and improve surface strength, thereby reducing fuzzing and dusting. In the main layer, if the amount of wet strength agent is too small, the improvement in wet strength is not significant, and the paper is prone to fuzzing and powdering after printing. Excessive wet strength agent may make the paper brittle, increase costs, and adversely affect impregnation performance. A small amount of nanocellulose has limited reinforcing effect, while a large amount may make the structure too dense, reducing resin penetration. Therefore, a mass ratio of bleached chemical pulp, wet strength agent, and nanocellulose of 1:(0.005-0.015):(0.0025-0.01) is more suitable. The main layer's function is not to directly improve the printing interface, but to provide a stable and moisture-resistant foundation for the entire structure. If the main body layer is too thin, the fiber network will not have sufficient load-bearing capacity, the wet strength system will have limited support surface, and the wet tensile strength and dimensional stability will decrease significantly, which may easily lead to problems such as misregistration, wrinkling or paper breakage. If the main body layer is too thick, although the strength will be further improved, the resin penetration path during the impregnation stage will increase significantly, the impregnation time will be prolonged, the uniformity of resin distribution will decrease, and it may affect the transparency and decorative effect after hot pressing. Therefore, the thickness of the main body layer should be in the range of 70-95μm.

[0024] Preferably, the transition layer comprises a barrier material, a filler, and an acrylic emulsion. The barrier material is a sheet-like material that forms a tortuous diffusion path in the coating, significantly increasing the path length for the lateral migration of water and solutes, thereby inhibiting the lateral diffusion of pigments with water and reducing dot gain and blooming. The barrier material includes at least one or a combination of graphene oxide and montmorillonite. Such materials can significantly increase the diffusion path length and improve lateral diffusion resistance even at low addition levels, while not completely blocking longitudinal penetration channels, thus achieving diffusion regulation rather than complete blockage. The filler constructs a capillary network that can quickly absorb moisture from the ink, accelerating the setting and drying speed. The filler is preferably kaolin or microporous silica. The acrylic emulsion acts as a binder phase, firmly fixing the filler and barrier material to form a stable microporous structure, while improving surface strength and preventing powdering. The transition layer allows water to enter rapidly, regulates pigment migration, and retains certain longitudinal channels to provide penetration paths for subsequent resin impregnation, thereby establishing a buffer and regulating interface between printing and impregnation. In the transition layer, the mass ratio of barrier material, filler, and acrylic emulsion is (0.001-0.015):(0.8-1.5):1. This allows the transition layer to possess both rapid water absorption capacity and effective suppression of lateral diffusion, while maintaining good mechanical stability. If the transition layer is too thin, the sheet-like barrier material will struggle to form a continuous, tortuous diffusion network, resulting in insufficient lateral diffusion suppression and difficulty in effectively controlling dot gain and blooming. If the transition layer is too thick, it may enhance the surface sealing tendency, affecting resin penetration in subsequent impregnation stages, while also increasing internal stress and the risk of cracking. Therefore, the thickness of the transition layer should be within the range of 5-15 μm to form an effective diffusion barrier structure without hindering resin impregnation.

[0025] Furthermore, the functional layer comprises silica, polyvinyl alcohol, acrylic emulsion, and a crosslinking agent. Silica has a high specific surface area and a hydrophilic surface, which improves the wettability of the paper surface, allowing water-based inks to spread quickly and achieve initial fixation. Polyvinyl alcohol forms a uniform hydrophilic film layer on the surface, improving wetting uniformity and enhancing surface bonding strength. The acrylic emulsion further enhances abrasion resistance and anti-blocking properties. The crosslinking agent forms a crosslinking network during drying, enabling the functional layer to maintain hydrophilicity while possessing good water resistance and mechanical stability; carbodiimide crosslinking agent is preferred. Because the functional layer is relatively thin, it does not form a completely sealed film, thus allowing for some swelling and resin penetration during resin impregnation. In the functional layer, the mass ratio of silica, polyvinyl alcohol, acrylic emulsion, and crosslinking agent is 1:(0.25-1.25):(0.75-2.75):(0.025-0.25). This ensures that the functional layer facilitates rapid wetting and setting of water-based inks while also providing good water and abrasion resistance. If the functional layer is too thin, it is difficult to form a continuous and stable hydrophilic network, resulting in uneven distribution of silica and polyvinyl alcohol and unstable wetting improvement. Conversely, if the functional layer is too thick, it is prone to forming a dense film, hindering resin penetration and increasing the risk of brittleness. Therefore, the thickness of the functional layer should ideally be in the range of 0.5-3 μm.

[0026] Furthermore, leveling agents and wetting agents need to be added to the functional layer. The addition of wetting agents effectively reduces the instantaneous surface tension of the functional layer and adjusts the interfacial tension difference between the ink and the paper surface, allowing the ink to spread quickly and evenly in a very short time. Wetting agents are typically polyether-modified siloxanes or nonionic surfactants, whose function is to increase the dynamic wetting rate, eliminate local interfacial energy differences, thereby reducing pinholes and local ink pooling, and improving dot boundary clarity, which is especially important under high-speed water-based gravure or flexographic printing conditions. Leveling agents mainly address the film uniformity problem during the coating stage. This is achieved by adjusting the surface tension gradient of the coating liquid, allowing it to spread and form a film more evenly during drying, thus creating a smooth and consistent micro-interfacial structure and improving printing resolution and color uniformity.

[0027] This application effectively solves problems such as unstable wetting, slow drying, dot diffusion, and fuzzing / dust shedding in water-based ink printing through the synergistic effect of a three-layer structure. At the same time, it avoids the defect of excessive surface sealing that hinders resin impregnation. Thus, it can achieve rapid ink absorption and clear imaging in the printing stage and maintain good resin permeability in the impregnation stage, thereby taking into account both the adaptability of water-based ink printing and the subsequent processing performance of decorative base paper.

[0028] Secondly, embodiments of this application provide a method for preparing decorative base paper suitable for water-based ink printing, used to prepare decorative base paper as described in any of the above technical solutions, the preparation method including the following steps: S100: Add wet strength agent and nanocellulose to bleached chemical pulp, form paper, and obtain the main layer; S200: A transition layer coating liquid is applied to the surface of the main layer and a first drying treatment is performed to obtain an intermediate paper layer; S300: A functional layer coating liquid is coated onto the transition layer of the intermediate paper layer and a second drying treatment is performed to obtain a decorative base paper suitable for water-based ink printing.

[0029] Since the decorative base paper must not only meet the imaging quality requirements of the printing stage, but also take into account the transparent decorative effect after impregnation and hot pressing, the preparation method of this application constructs each layer of the decorative base paper in steps and dries them separately, which is conducive to each layer playing an independent role, while ensuring strong interlayer bonding and structural stability.

[0030] Preferably, in step S100, a wet strength agent and nanocellulose are added to the bleached chemical pulp and paper is formed to create the main layer. Since the decorative base paper is subjected to a large amount of water during water-based ink printing, insufficient wet strength can weaken fiber bonds due to water absorption, leading to problems such as fuzzing, dusting, and dimensional instability. Therefore, adding a wet strength agent during the papermaking stage can form a water-resistant chemical or covalent bond structure between fibers, improving wet tensile strength. Nanocellulose enhances the bonding between fibers at the microscale and fills micropores, making the structure more uniform and stable. Introducing the wet strength system and nano-reinforcing system during the papermaking stage allows the entire paper sheet to possess water-resistant swelling resistance and good mechanical support from its internal structure. If surface reinforcement is performed later, the wet structural stability cannot be fundamentally improved; therefore, this step must be the starting point of the preparation process. The beating degree of bleached chemical pulp is 28-38°SR. The fibers have sufficient binding force to ensure wet strength, while retaining a moderate porosity structure to facilitate the absorption of water-based inks and subsequent resin penetration. If the beating degree is lower than this range, there will be more fuzz on the fiber surface, fewer binding points, loose paper structure, insufficient strength, and easy fuzzing and dusting, which will affect the printing stability of water-based inks. If the beating degree exceeds this range, the fibers will be excessively fine, the paper structure will be too dense, the porosity will decrease, resin impregnation will be difficult, and the water absorption rate will be too slow or uneven, affecting the printing drying behavior.

[0031] Further, in step S200, a transition layer coating liquid is applied to the surface of the main layer and subjected to a first drying treatment. The function of the transition layer is to regulate the mass transfer behavior between water and pigment in the water-based ink, that is, to ensure that water can be absorbed quickly while inhibiting the lateral diffusion of pigment. Therefore, the transition layer must be formed before the functional layer is coated, and its film formation must be stabilized through the first drying treatment. If the transition layer is not fully dried first, its microstructure will be destroyed during the coating of the functional layer, resulting in interlayer mixing and uncontrolled pore structure, which in turn affects the diffusion control effect and the formation of subsequent resin impregnation channels. Since the transition layer contains fillers, sheet-like barrier materials and acrylic emulsion, its structure formation depends on the full film formation of emulsion particles and the stable arrangement of sheet-like materials. Acrylic emulsions usually have a certain minimum film-forming temperature (MFT). Only at temperatures above the MFT can the emulsion particles fully fuse to form a continuous phase, thereby fixing the fillers and barrier materials in a stable structure. If the drying temperature is too low, the film formation will be insufficient, the structure will be loose, the sheet barrier material will be difficult to distribute stably, and the diffusion control capability will be insufficient. If the temperature is too high, it may cause an excessive moisture gradient inside the base paper, leading to internal stress accumulation, warping or microcracks, while also increasing energy consumption. Therefore, the temperature of the first drying treatment is 105-120℃, which can ensure that the emulsion forms a film and the sheet material structure is stable, while avoiding thermal damage or structural stress problems, thereby forming a stable diffusion control layer.

[0032] Furthermore, in step S300, a functional layer coating liquid is applied to the transition layer of the intermediate paper layer, followed by a second drying treatment. The main task of the functional layer is to construct a printing interface suitable for water-based inks, with the core being to improve surface hydrophilicity, enhance dynamic wetting properties, and strengthen surface strength. After applying the functional layer coating liquid, the second drying treatment ensures that the functional layer forms a stable but not overly dense interface structure, thus meeting the requirements for rapid wetting and fixation in the printing stage without hindering subsequent resin impregnation. If the functional layer and the transition layer are coated simultaneously or dried without separation, it can easily lead to mixed interface functions, affecting the printing effect and potentially causing surface blockage, thereby weakening the resin penetration ability. The temperature of the second drying treatment is 90-105℃, which ensures, on the one hand, that polyvinyl alcohol and acrylic emulsion form a stable film-forming structure, and on the other hand, controls the degree of crosslinking, allowing the functional layer to maintain a certain degree of hydrophilicity and swelling capacity, thus performing well in the printing stage and not forming a barrier in the impregnation stage.

[0033] Preferably, the preparation method of the functional layer coating liquid includes the following steps: S310. Dissolve polyvinyl alcohol in deionized water to obtain a polyvinyl alcohol solution; S320. Add silica to a polyvinyl alcohol solution for dispersion treatment to obtain a dispersion. S330. Add acrylic emulsion to dispersion, then add crosslinking agent, and mix to obtain functional layer coating liquid.

[0034] Preferably, in step S310, polyvinyl alcohol (PVA) is dissolved in deionized water. PVA is a hydrophilic polymer with strong hydrogen bonds between its molecular chains. It must be fully dissolved and form a homogeneous molecular solution before it can serve as a stable continuous phase for subsequent inorganic particle dispersion and emulsion blending. If other components are added before PVA is fully dissolved, it can lead to localized gelation or agglomeration, thus affecting the uniformity of the final coating. Therefore, forming a stable and homogeneous PVA solution first is a prerequisite for ensuring the uniformity of the system.

[0035] Further, in step S320, silica is added to the PVA solution for dispersion treatment. Silica is typically in the form of nano- or micron-sized particles with a high specific surface area and strong surface hydroxyl groups, making it prone to agglomeration. Insufficient dispersion will lead to particle agglomerates, causing rough spots or defects in the coating and affecting printing smoothness and wetting uniformity. PVA molecular chains can interact with the hydroxyl groups on the silica surface through hydrogen bonds, forming an adsorption layer on the particle surface, thereby improving dispersion stability. Therefore, sufficient dispersion of silica must be completed before the addition of the acrylic emulsion to ensure a stable dispersion structure in the PVA system. The dispersion treatment employs ultrasonic dispersion for 0.5-1 hours. Ultrasonic cavitation can break the weak van der Waals forces and hydrogen bond aggregation structures between particles, causing the agglomerates to dissociate into smaller particles and improving dispersion uniformity. Compared with simple mechanical stirring, ultrasound can provide higher dispersion energy in a shorter time, reducing the risk of particle agglomeration.

[0036] Furthermore, in step S330, the acrylic emulsion is added first, followed by the crosslinking agent. The acrylic emulsion, as a film-forming component, needs to be uniformly distributed in the dispersion system and form a composite network with PVA and silica. If the crosslinking agent is added too early, it may react prematurely with the carboxyl groups in the PVA or emulsion, causing a rapid increase in system viscosity or even localized gelation, affecting the coating's workability. Therefore, the crosslinking agent is usually added after the system is uniformly mixed, close to the coating stage, to control the crosslinking reaction rate and time, thereby forming a moderately crosslinked network during the drying stage.

[0037] Preferably, S300 further includes: S301, calendering the decorative base paper. Calendering not only improves surface smoothness and printing resolution, but also homogenizes the surface pore structure and stabilizes ink absorption behavior. In addition, calendering can improve thickness uniformity and interlayer bonding, and improve the stability of subsequent impregnation and hot pressing processes. Example 1

[0038] This embodiment provides a decorative base paper suitable for water-based ink printing, comprising, from bottom to top: a main layer, a transition layer, and a functional layer. The main layer comprises bleached chemical pulp, PAE wet strength agent, and nanocellulose; the transition layer comprises graphene oxide, kaolin, and acrylic emulsion; and the functional layer comprises silica, polyvinyl alcohol, acrylic emulsion, and carbodiimide crosslinking agent. The thickness of the main layer is 70 μm, the thickness of the transition layer is 5 μm, and the thickness of the functional layer is 3 μm. The decorative base paper is prepared using the following method: S100: PAE wet strength agent and nanocellulose are added to bleached chemical pulp with a freeness of 28°SR, and the pulp is formed into paper to obtain the main layer. S200. A transition layer coating liquid is applied to the surface of the main layer and a first drying treatment is performed at 105°C to obtain an intermediate paper layer. S300: A functional layer coating liquid is coated on the transition layer of the intermediate paper layer and a second drying treatment is performed at 90°C to obtain a decorative base paper suitable for water-based ink printing. Example 2

[0039] This embodiment provides a decorative base paper suitable for water-based ink printing, comprising, from bottom to top: a main layer, a transition layer, and a functional layer. The main layer includes bleached chemical pulp, PAE wet strength agent, and nanocellulose; the transition layer includes montmorillonite, microporous silica, and acrylic emulsion; the functional layer includes silica, polyvinyl alcohol, acrylic emulsion, and carbodiimide crosslinking agent. The thickness of the main layer is 95 μm, the thickness of the transition layer is 15 μm, and the thickness of the functional layer is 0.5 μm. The decorative base paper is prepared by the following method: S100: PAE wet strength agent and nanocellulose are added to bleached chemical pulp with a freeness of 38°SR, and the pulp is formed into paper to obtain the main layer. S200. A transition layer coating liquid is applied to the surface of the main layer and a first drying treatment is performed at 120°C to obtain an intermediate paper layer. S300: A functional layer coating liquid is coated on the transition layer of the intermediate paper layer and a second drying treatment is performed at 105°C to obtain a decorative base paper suitable for water-based ink printing. Example 3

[0040] This embodiment provides a decorative base paper suitable for water-based ink printing, comprising, from bottom to top: a main layer, a transition layer, and a functional layer. The main layer comprises bleached chemical pulp, PAE wet strength agent, and nanocellulose; the transition layer comprises graphene oxide, kaolin, and acrylic emulsion; and the functional layer comprises silica, polyvinyl alcohol, acrylic emulsion, and carbodiimide crosslinking agent. The thickness of the main layer is 80 μm, the thickness of the transition layer is 10 μm, and the thickness of the functional layer is 2 μm. The decorative base paper is prepared using the following method: S100: PAE wet strength agent and nanocellulose are added to bleached chemical pulp with a freeness of 35°SR, and the pulp is formed into paper to obtain the main layer. S200. A transition layer coating liquid is applied to the surface of the main layer and a first drying treatment is performed at 110°C to obtain an intermediate paper layer. S300: Coat the functional layer coating liquid onto the transition layer of the intermediate paper layer and perform a second drying treatment at 100°C to obtain a decorative base paper suitable for water-based ink printing. The preparation method of the functional layer coating liquid includes the following steps: S310. Dissolve polyvinyl alcohol in deionized water to obtain a polyvinyl alcohol solution; S320. Add silica to a polyvinyl alcohol solution and perform ultrasonic dispersion treatment for 0.5 h to obtain a dispersion. S330. Add acrylic emulsion to dispersion, then add crosslinking agent, and mix to obtain functional layer coating liquid. Example 4

[0041] This embodiment provides a decorative base paper suitable for water-based ink printing, comprising, from bottom to top: a main layer, a transition layer, and a functional layer. The main layer comprises bleached chemical pulp, PAE wet strength agent, and nanocellulose; the transition layer comprises graphene oxide, kaolin, and acrylic emulsion; and the functional layer comprises silica, polyvinyl alcohol, acrylic emulsion, and carbodiimide crosslinking agent. The thickness of the main layer is 80 μm, the thickness of the transition layer is 10 μm, and the thickness of the functional layer is 2 μm. The decorative base paper is prepared using the following method: S100: PAE wet strength agent and nanocellulose are added to bleached chemical pulp with a freeness of 35°SR, and the pulp is formed into paper to obtain the main layer. S200. A transition layer coating liquid is applied to the surface of the main layer and a first drying treatment is performed at 110°C to obtain an intermediate paper layer. S300: Coat the functional layer coating liquid onto the transition layer of the intermediate paper layer and perform a second drying treatment at 100°C to obtain a decorative base paper suitable for water-based ink printing. The preparation method of the functional layer coating liquid includes the following steps: S310. Dissolve polyvinyl alcohol in deionized water to obtain a polyvinyl alcohol solution; S320. Add silica to a polyvinyl alcohol solution and perform ultrasonic dispersion treatment for 1 hour to obtain a dispersion. S330. Add acrylic emulsion to dispersion, then add crosslinking agent, and mix to obtain functional layer coating liquid; The S300 also includes: S301. Calender the decorative base paper.

[0042] Comparative Example 1 This comparative example provides a decorative base paper, which differs from Example 1 in that it does not have a transition layer and the preparation method does not include step S200.

[0043] Comparative Example 2 This comparative example provides a decorative base paper, which differs from Example 1 in that it does not have a functional layer and the preparation method does not include step S300.

[0044] Comparative Example 3 This comparative example provides a decorative base paper, which differs from Example 1 in that it includes, from bottom to top, a main layer, a functional layer, and a transition layer. The preparation method involves first performing step S300 and then step S200.

[0045] This application has undergone multiple experiments, and some of the test results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0046] The decorative base paper used in Examples 1-4 and Comparative Examples 1-3 was then subjected to the following tests: Surface performance testing: The water absorption and dyne value of the decorative base paper of Examples 1-4 and Comparative Examples 1-3 were tested respectively; Printing performance test: Water-based gravure printing was used with a line speed of 120m / min and a screen density of 100lpi. The same set of water-based inks and the same drying air volume were used to print on the decorative base paper in Examples 1-4 and Comparative Examples 1-3, respectively. After printing, the image uniformity was scored (0-5 points, the lower the y score, the better). Appearance test after impregnation-hot pressing: The decorative base paper in Examples 1-4 and Comparative Examples 1-3 was impregnated with melamine resin, and then hot-pressed to obtain the white spot area ratio after hot pressing. The test results are shown in Table 1.

[0047] Table 1 As can be seen from Table 1, the performance of Examples 1-4 is superior to that of Comparative Examples 1-3, indicating that the decorative base paper and preparation method described in this application can bring better performance, especially Example 4. The water absorption of Comparative Example 1 is significantly higher, indicating that the lack of a transition layer leads to excessive water absorption, which in turn affects the uniformity after printing and makes white spots more likely to appear after hot pressing; the dyne value of Comparative Example 2 is significantly lower, indicating that the lack of a functional layer leads to insufficient surface function, poor wetting and spreading of water-based inks, and unstable printing image quality; white spots are more likely to appear in Comparative Example 3. Although the water absorption is reduced, other properties are poor, indicating that the surface structure is abnormal after the order of the transition layer and functional layer is reversed. The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A decorative base paper suitable for water-based ink printing, characterized in that, From bottom to top, it includes: main layer, transition layer, and functional layer. The main layer comprises bleached chemical pulp, wet strength agent, and nanocellulose; The transition layer includes a barrier material, a filler, and an acrylic emulsion; The functional layer comprises silica, polyvinyl alcohol, acrylic emulsion, and crosslinking agent.

2. The decorative base paper according to claim 1, characterized in that, The thickness of the main body layer is 70-95 μm; and / or The thickness of the transition layer is 5-15 μm; and / or The thickness of the functional layer is 0.5-3 μm.

3. The decorative base paper according to claim 1, characterized in that, In the main body layer, the mass ratio of the bleaching chemical pulp, the wet strength agent, and the nanocellulose is 1:(0.005-0.015):(0.0025-0.01); and / or In the transition layer, the mass ratio of the barrier material, the filler, and the acrylic emulsion is (0.001-0.015):(0.8-1.5):1; and / or In the functional layer, the mass ratio of the silica, the polyvinyl alcohol, the acrylic emulsion and the crosslinking agent is 1:(0.25-1.25):(0.75-2.75):(0.025-0.25).

4. The decorative base paper according to claim 3, characterized in that, In the main body layer, the bleached chemical pulp comprises bleached softwood pulp and bleached hardwood pulp, wherein the mass ratio of the bleached softwood pulp to the bleached hardwood pulp is 1:(1.2-2.3); and / or In the transition layer, the barrier material includes at least one or a combination of graphene oxide and montmorillonite.

5. A method for preparing decorative base paper suitable for water-based ink printing, used to prepare the decorative base paper as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: S100. Add a wet strength agent and nanocellulose to the bleached chemical pulp, and form it into paper to obtain the main body layer; S200: A transition layer coating liquid is applied to the surface of the main body layer and a first drying treatment is performed to obtain an intermediate paper layer; S300: A functional layer coating liquid is coated onto the transition layer of the intermediate paper layer and a second drying process is performed to obtain the decorative base paper suitable for water-based ink printing.

6. The preparation method according to claim 5, characterized in that, The preparation method of the functional layer coating liquid includes the following steps: S310. Dissolve polyvinyl alcohol in deionized water to obtain a polyvinyl alcohol solution; S320. The silica is added to the polyvinyl alcohol solution for dispersion treatment to obtain a dispersion. S330. Add the acrylic emulsion to the dispersion, then add the crosslinking agent, and mix to obtain the functional layer coating liquid.

7. The preparation method according to claim 6, characterized in that, The dispersion treatment is ultrasonic dispersion treatment; and / or The dispersion treatment time is 0.5-1 hour; and / or The crosslinking agent is a carbodiimide crosslinking agent.

8. The preparation method according to claim 5, characterized in that, The temperature of the first drying treatment is 105-120℃; and / or The temperature for the second drying process is 90-105℃.

9. The preparation method according to claim 5, characterized in that, The freeness of the bleached chemical pulp is 28-38°SR.

10. The preparation method according to claim 5, characterized in that, The S300 also includes: S301. Calender the decorative base paper.

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