Environment-friendly decorative paper with multi-layer structure and preparation method of environment-friendly decorative paper

Abstract

The invention discloses environment-friendly decorative paper with a multi-layer structure and a preparation method of the environment-friendly decorative paper, and relates to the technical field of multi-layer composite materials. According to the environment-friendly decorative paper, the base layer, the bonding layer, the functional layer, the printing decorative layer and the surface protection layer are attached to one another, and the environment-friendly decorative paper of the multi-layer structure is prepared. Wherein the base layer is made of raw materials such as wood pulp fibers and bamboo pulp fibers which serve as biomass conversion materials, the bonding layer is made of modified polyurethane resin, tight combination of the bonding layer, the base layer and the functional layer is achieved, the printing decoration layer is made of water-based ink, and the surface protection layer has the excellent protection characteristic. The environment-friendly decorative paper with the multi-layer structure has environment friendliness and functionality, all the layers are tightly combined and are not prone to separation, the environment-friendly decorative paper can be widely applied to the decoration fields of furniture, building materials and the like, the problems that traditional decorative paper is poor in environment friendliness, single in function, short in service life and the like are solved, and the environment-friendly decorative paper has good application prospects.

Description

Technical Field

[0001] This application relates to the field of multilayer composite material technology, and in particular to an environmentally friendly decorative paper with a multilayer structure and its preparation method. Background Technology

[0002] With the improvement of people's living standards and the enhancement of environmental awareness, higher requirements are being placed on the environmental friendliness, functionality, and aesthetics of decorative materials. At the same time, the use of renewable and biodegradable biomass conversion materials to prepare decorative products has become a core direction for the industry's environmental development. Decorative paper, as a widely used decorative material in furniture surfaces, interior decoration, flooring veneers, and other fields, directly affects the decorative effect and user experience. Biomass conversion materials (such as wood pulp fiber and bamboo pulp fiber) are gradually becoming the preferred raw materials for the preparation of environmentally friendly decorative paper due to their renewable, biodegradable, environmentally friendly characteristics and certain structural advantages.

[0003] Existing multi-layer decorative papers generally suffer from numerous defects and fail to make reasonable use of the advantages of biomass conversion materials such as wood pulp fiber and bamboo pulp fiber, making it difficult to balance environmental protection and overall performance. Firstly, existing multi-layer decorative papers rely excessively on chemically synthesized raw materials or non-environmentally friendly fiber components, resulting in insufficient environmental performance. They are prone to releasing harmful gases during production and use, endangering human health and the ecological environment, which contradicts the current development trend of biomass material resource utilization. Secondly, existing multi-layer decorative papers often lack functionality; the products are easily affected by moisture and deformation, and the surface is prone to wear, aging, and yellowing, making it difficult to simultaneously meet multiple usage requirements. Finally, and most importantly, the interlayer bonding strength of existing multi-layer decorative papers is often poor, leading to peeling and delamination between layers, severely affecting the product's lifespan.

[0004] Therefore, combining the renewable and environmentally friendly characteristics of biomass conversion materials such as wood pulp fiber and bamboo pulp fiber, developing a decorative paper that is environmentally friendly, has excellent functionality and a stable multi-layer structure, and fully leverages the application advantages of biomass conversion materials, has become the current industry development trend and is in line with the industrial policies of environmental protection, energy conservation and resource recycling. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a multi-layered environmentally friendly decorative paper and its preparation method. This application presents a multi-layered environmentally friendly decorative paper by bonding together a base layer, an adhesive layer, a functional layer, a printed decorative layer, and a surface protective layer. The base layer is made from wood pulp fiber, bamboo pulp fiber, and other raw materials; the adhesive layer is a modified polyurethane resin, achieving a tight bond with the base layer and functional layers; the printed decorative layer uses water-based ink; and the surface protective layer possesses excellent protective properties. This multi-layered environmentally friendly decorative paper balances environmental friendliness and functionality, with each layer tightly bonded and unlikely to detach. It can be widely used in furniture, building materials, and other decorative fields, solving the problems of poor environmental performance, limited functionality, and short service life of traditional decorative papers, and has promising application prospects.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a multi-layered environmentally friendly decorative paper, comprising, from bottom to top, a base layer, an adhesive layer, a functional layer, a printed decorative layer, and a surface protective layer bonded together; the base layer is made of wood pulp fiber, bamboo pulp fiber, reinforcing agent, and sizing agent; the adhesive layer is a modified polyurethane resin; the functional layer includes polyacrylate resin, epoxy resin, antibacterial agent, moisture-proof agent, and dispersant; the printed decorative layer is water-based ink; and the surface protective layer includes UV-curable resin, silicone resin, compatibilizer, abrasion resistant agent, photoinitiator, and anti-yellowing agent.

[0008] In one feasible implementation scheme, the reinforcing agent used in the base layer may be selected from, but is not limited to, any of the following known materials: starch, sodium carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol, nano silica, nano calcium carbonate, etc.

[0009] The materials that can be selected for the sizing agent used in the base layer include, but are not limited to, any one of the following known materials: rosin, alkyl ketene dimer, alkenyl succinic anhydride, styrene-maleic anhydride copolymer, etc.

[0010] The antibacterial agents used in the functional layer may be selected from, but are not limited to, any of the following known materials: nano silver, nano zinc oxide, nano copper oxide, isothiazolinone, chitosan, tea polyphenols, artemisia extract, etc.

[0011] The materials that can be used as moisture-proof agents in the functional layer include, but are not limited to, any one of the following known materials: montmorillonite, bentonite, calcium chloride, silica gel, paraffin wax, etc.

[0012] The dispersant used in the functional layer may be selected from, but is not limited to, any of the following known materials: sodium dodecylbenzenesulfonate, dodecyl acetate, sodium oleate, polyoxyethylene ether, fatty alcohol polyoxyethylene ether, etc.

[0013] The compatibilizer used in the surface protective layer may be made of materials including, but not limited to, any of the following known materials: polyethylene grafted with maleic anhydride, polypropylene grafted with maleic anhydride, etc.

[0014] The wear-resistant agent used in the surface protective layer can be made of materials including, but not limited to, any of the following known materials: nano alumina, nano zirconium oxide, silicon carbide micro powder, polytetrafluoroethylene micro powder, polyimide micro powder, etc.

[0015] The photoinitiator used in the surface protective layer may be selected from, but is not limited to, any of the following known materials: 2,2-dimethylolpropionic acid, benzophenone, diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride, etc.

[0016] The anti-yellowing agent used in the surface protective layer can be selected from, but is not limited to, any of the following known materials: 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, etc.

[0017] In one feasible implementation, the thickness of the multi-layered environmentally friendly decorative paper is 120-200μm, wherein the thickness of the base layer accounts for 40-60%, the thickness of the adhesive layer accounts for 10-20%, the thickness of the functional layer accounts for 10-20%, the thickness of the printed decorative layer accounts for 5-15%, and the thickness of the surface protective layer accounts for 5-15%.

[0018] In the multi-layered environmentally friendly decorative paper prepared in this application, the base layer, as the load-bearing layer, has a thickness of 40-60% to ensure the density and strength of the fiber skeleton and prevent overall deformation of the environmentally friendly decorative paper; the adhesive layer is thick enough to form a continuous interface, and the functional layer is thick enough to ensure the effective content of antibacterial and moisture-proof components without causing excessive stress at the interface with the upper and lower layers due to excessive thickness; the printing layer is thin and uniform, which can avoid blurring of patterns or ink accumulation; the protective layer is thin and relatively dense due to curing, which can form effective protection without affecting the adhesion of the decorative paper.

[0019] In one feasible implementation, the mass ratio of the wood pulp fiber, bamboo pulp fiber, reinforcing agent and sizing agent in the base layer is (40-50):(40-50):(2-5):(1-5).

[0020] In one feasible implementation, the modified polyurethane resin in the adhesive layer is prepared by:

[0021] Ethyl acetate, polyurethane resin, and dried polyethylene glycol were added sequentially to the reactor. Nitrogen gas was purged for protection, and the temperature was raised to 50-60℃. The mixture was stirred at 200-300 rpm for 20-40 minutes to obtain a mixture.

[0022] Isocyanate-based silane coupling agent is added dropwise to the mixture, followed by catalyst and defoamer, and the temperature is raised to 65-70℃. The mixture is stirred at 350-450 rpm for 2-3 hours, then water is added, and stirring is continued for 30-60 minutes under the same conditions to obtain the reaction product. The modified polyurethane resin is obtained by vacuum distillation of the reaction product.

[0023] The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-based silane coupling agent, catalyst, defoamer and water is (40-50): (30-40): (10-15): (2-6): (0.1-0.5): (1-3): (5-10).

[0024] In one feasible implementation, the catalyst comprises any one of dibutyltin dilaurate, dioctyltin dilaurate, and stannous octoate; the defoamer comprises any one of polyoxypropylene glycerol ether, polydimethylsiloxane, and glyceryl monostearate.

[0025] The hydrophilic segments of polyethylene glycol can be inserted into the polyurethane resin molecular chain, increasing the flexibility of the polyurethane resin and its compatibility with polyacrylate and epoxy resins in the functional layer, thereby improving interlayer bonding. Furthermore, the -NCO groups of the isocyanate-based silane coupling agent react with the -OH groups in polyethylene glycol to introduce siloxanes; the siloxanes react with subsequently added water to hydrolyze and generate silanol groups, which further react with the hydroxyl groups on the surface of the base layer and functional layer to form siloxane bonds, significantly improving interfacial bonding. Simultaneously, the main materials of the base layer, adhesive layer, and functional layer are all rich in oxygen-containing or nitrogen-containing groups, so hydrogen bonds can be formed between the layers simultaneously, further enhancing interfacial bonding.

[0026] In one feasible implementation, the dried polyethylene glycol is obtained by drying polyethylene glycol at 100-120°C for 3-4 hours, and its molecular weight is 1200-2000.

[0027] Isocyanate groups are very sensitive to moisture and react with water to produce carbon dioxide. Carbon dioxide forms bubbles in the resin, which can easily disrupt the continuity of the adhesive layer. Polyethylene glycol is hygroscopic and therefore requires drying treatment to ensure that there is no moisture interference, thus ensuring the smooth progress of modification.

[0028] Furthermore, if the molecular weight of polyethylene glycol is too low, the molecular chain segments will be too short, resulting in an insignificant modification effect; if the molecular weight is too high, it will increase the resin viscosity, leading to difficulties in coating. Controlling the molecular weight of polyethylene glycol can achieve a balance between improving flexibility and coating performance in the prepared modified polyurethane resin.

[0029] In one feasible implementation, the isocyanate-based silane coupling agent comprises any one or more of isocyanate-based methyltrimethoxysilane, isocyanate-based propyltrimethoxysilane, isocyanate-based propylmethyldimethoxysilane, isocyanate-based methyltriethoxysilane, and isocyanate-based propyltriethoxysilane.

[0030] In one feasible implementation, the mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent, moisture-proof agent and dispersant in the functional layer is (50-60):(25-35):(2-8):(3-10):(1-2).

[0031] In one feasible implementation, the water-based ink in the printed decorative layer comprises styrene-methyl methacrylate resin, pigment, water, leveling agent, anti-migration agent, and film-forming agent; the mass ratio of the styrene-methyl methacrylate resin, pigment, water, leveling agent, anti-migration agent, and film-forming agent is (20-40):(10-15):(40-60):(0.1-1.5):(0.5-3):(2-8).

[0032] Styrene-methyl methacrylate resin forms a stable emulsion in water, which serves as a carrier for pigments. After film formation, it makes the pigments adhere more firmly. At the same time, water acts as a solvent, which does not produce excessive volatile organic solvents, reducing VOC emissions from the source and making it more environmentally friendly.

[0033] In one feasible implementation, the pigments used in the printed decorative layer may be selected from, but are not limited to, any of the following known materials: titanium dioxide, carbon black, iron oxide red, ultramarine blue, phthalocyanine blue, etc.

[0034] The leveling agents used in the printed decorative layer can be made from materials including, but not limited to, any of the following known materials: BYK-307, BYK-327, BYK-329, BYK-361N, etc.

[0035] The materials that can be used as anti-migration agents in printed decorative layers include, but are not limited to, any of the following known materials: polyethylene wax emulsion, polytetrafluoroethylene emulsion, polyamide wax, etc.

[0036] The film-forming agent used in the printed decorative layer may be made of materials including, but not limited to, any of the following known materials: dodecyl alcohol ester, polyvinyl acetate, dipropylene glycol butyl ether, etc.

[0037] In one feasible implementation, the mass ratio of the UV-curable resin, silicone resin, compatibilizer, abrasion resistant agent, photoinitiator, and anti-yellowing agent in the surface protective layer is (50-75):(5-25):(10-15):(1-10):(1-8):(1-5); the UV-curable resin includes any one or more of epoxy acrylate resin, polyurethane acrylate resin, and polyester acrylate resin; the silicone resin includes any one or more of phenyl vinyl silicone resin, acrylic silicone oil, and methyl MQ silicone resin.

[0038] In this application, the UV-curable resin of the surface protective layer is combined with a silicone resin containing stable Si-O bonds, which is rapidly cured and cross-linked under UV light to form a dense coating with excellent weather resistance, hydrophobicity and high temperature resistance, and isolates it from external physical wear and chemical corrosion.

[0039] Secondly, this application provides a method for preparing a multi-layered environmentally friendly decorative paper, comprising the following steps:

[0040] Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent and sizing agent, and stir at 500-600 rpm for 1-2 hours to make pulp for later use.

[0041] The pulp is fed into a wire paper machine for papermaking, and after two presses to dewater it, it is baked in hot air at 70-80℃ for 4-6 hours, and then cut to obtain the base layer.

[0042] Modified polyurethane resin was coated onto the upper surface of the prepared base layer by roller coating at a coating roller speed of 20-30 r / min and a coating pressure of 0.3-0.5 MPa. The base layer was then dried at 80-90℃ for 1-2 h to obtain a composite substrate with an adhesive layer.

[0043] Weigh out polyacrylate resin, epoxy resin, antibacterial agent, moisture-proofing agent and dispersant according to the proportion, add them to the mixing equipment, and stir at 300-400 rpm for 20-30 min to obtain the first mixture; apply the first mixture to the upper surface of the adhesive layer by roller coating under the conditions of coating roller speed of 15-25 r / min and coating pressure of 0.6-0.8 MPa, and dry it at 90-100℃ for 2-3 h after coating to obtain the composite substrate with functional layer;

[0044] Water-based ink is prepared according to a certain ratio. After corona treatment of the upper surface of the functional layer, the water-based ink is printed on the upper surface of the functional layer by gravure printing. After printing, it is dried at 70-80℃ for 0.5-1h to obtain a composite substrate with a printed decorative layer.

[0045] Weigh out the UV-curable resin, silicone resin, compatibilizer, abrasion resistant agent, photoinitiator, and anti-yellowing agent according to the specified proportions, add them to a mixing device, and stir at 250-350 rpm for 15-25 minutes to obtain a second mixture. Apply the second mixture to the upper surface of the printed decorative layer by roller coating at a coating roller speed of 25-35 rpm and a coating pressure of 0.2-0.4 MPa. Then, cure it by UV light irradiation with a wavelength of 365-425 nm and a curing energy of 800-1200 mJ / cm². 2 This yields a composite substrate with a surface protective layer, namely the multi-layered environmentally friendly decorative paper.

[0046] This application provides a method for preparing a multi-layered environmentally friendly decorative paper. Corona treatment increases the surface polarity of the functional layers, enhancing the adhesion of water-based inks to their surface, thereby enabling precise transfer of gravure printing patterns. The method utilizes wavelengths of 365-425nm and 800-1200mJ / cm². 2 The curing energy ensures that the surface protective layer cures quickly and fully, forming a dense protective coating, while avoiding over-curing that could cause the coating to become brittle.

[0047] Beneficial technical effects:

[0048] In the multi-layered environmentally friendly decorative paper prepared in this application, the base layer uses wood pulp fiber and bamboo pulp fiber, which are biomass conversion materials. With the synergistic effect of reinforcing agents and sizing agents, they interweave through a papermaking process to form a stable and environmentally friendly fiber skeleton, providing fundamental support strength for the overall environmentally friendly decorative paper. Secondly, polyurethane resin and polyethylene glycol are composited together using isocyanate silane coupling agents to form a modified polyurethane resin rich in oxygen-containing and nitrogen-containing groups. This modified polyurethane resin, used as the adhesive layer, possesses both high adhesion and flexibility, eliminating interfacial stress between the adhesive layer and the base layer and functional layers, strengthening the interlayer bonding strength of the adhesive layer, base layer, and functional layers, and preventing delamination. Furthermore, the functional layer uses a composite of polyacrylate resin and epoxy resin as its matrix, exhibiting good weather resistance and corrosion resistance, and is also rich in oxygen-containing groups, making it compatible with the adhesive layer. Its composition also includes antibacterial and moisture-proof additives, achieving dual functions of antibacterial, mildew-proof, and moisture-proof properties, further extending the service life of the prepared environmentally friendly decorative paper. Furthermore, the water-based inks used in the printing decorative layer employ styrene-methyl methacrylate resin as a binder, which can match the polyacrylate and epoxy resins of the functional layers, enhancing interlayer adhesion. The water-based inks use water as a solvent, avoiding VOC emissions from organic solvents while ensuring the clarity of the decorative patterns. Finally, the surface protective layer is formed by the co-curing of UV-cured resin and silicone resin, creating a dense protective layer that adheres tightly to the printing decorative layer. Combined with anti-yellowing and abrasion-resistant components, it isolates the paper from various external physical or chemical erosions, significantly extending the service life of the multi-layered environmentally friendly decorative paper. Attached Figure Description

[0049] Figure 1 This is a structural diagram of the multi-layered environmentally friendly decorative paper provided in this application.

[0050] Figure 2 This is a schematic diagram of the preparation method of the multi-layered environmentally friendly decorative paper provided in this application. Detailed Implementation

[0051] To facilitate understanding of the content described in this application, the technical solutions described herein are further explained below with reference to specific embodiments; however, this application is not limited thereto. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the protection scope of this application.

[0052] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0053] The following will describe in detail the preparation method of the multi-layered environmentally friendly decorative paper provided in this application, with reference to different embodiments.

[0054] like Figure 1 As shown, this invention provides a multi-layered environmentally friendly decorative paper, comprising, from bottom to top, a base layer 1, an adhesive layer 2, a functional layer 3, a printed decorative layer 4, and a surface protective layer 5, which are bonded together sequentially. The base layer 1 is made of wood pulp fiber, bamboo pulp fiber, reinforcing agent, and sizing agent. The adhesive layer 2 is a modified polyurethane resin. The functional layer 3 includes polyacrylate resin, epoxy resin, antibacterial agent, moisture-proof agent, and dispersant. The printed decorative layer 4 is a water-based ink. The surface protective layer 5 includes UV-curable resin, silicone resin, compatibilizer, abrasion resistant agent, photoinitiator, and anti-yellowing agent.

[0055] Example 1

[0056] like Figure 2 As shown, a method for preparing a multi-layered environmentally friendly decorative paper includes the following steps:

[0057] 1. Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent (starch) and sizing agent (rosin), stir at 600 rpm for 1 hour to make pulp for later use;

[0058] 2. The pulp is fed into a wire paper machine for papermaking. After two presses and dewatering, it is baked in hot air at 70℃ for 6 hours. After cutting, the base layer 1 is obtained, in which the mass ratio of wood pulp fiber, bamboo pulp fiber, reinforcing agent (starch) and sizing agent (rosin) is 45:50:2:3.

[0059] 3. Add ethyl acetate, polyurethane resin, and dried polyethylene glycol (obtained by drying at 100℃ for 4 hours, with a molecular weight of 1200) sequentially to the reaction vessel, purge with nitrogen, heat to 50℃, and stir at 200 rpm for 40 minutes to obtain a mixture.

[0060] 4. Add isocyanate-based methyltrimethoxysilane dropwise to the mixture, followed by the catalyst (dibutyltin dilaurate) and defoamer (polyoxypropylene glycerol ether), and heat to 65°C. Stir at 350 rpm for 3 hours, then add water and continue stirring for 30 minutes under the same conditions to obtain the reaction product. Continue to distill the reaction product under reduced pressure to obtain the modified polyurethane resin.

[0061] The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-based methyltrimethoxysilane, catalyst (dibutyltin dilaurate), defoamer (polyoxypropylene glycerol ether), and water is 45:35:10:2:0.5:2.5:5.

[0062] 5. The modified polyurethane resin is coated onto the upper surface of the prepared base layer 1 by roller coating at a coating roller speed of 20 r / min and a coating pressure of 0.3 MPa, and then dried at 80℃ for 2 h to obtain a composite substrate with adhesive layer 2.

[0063] 6. Weigh out polyacrylate resin, epoxy resin, antibacterial agent (nano silver), moisture-proof agent (montmorillonite), and dispersant (sodium dodecylbenzene sulfonate) according to the proportion, add them to the mixing equipment, and stir at 300 rpm for 30 min to obtain the first mixture; coat the first mixture onto the upper surface of the adhesive layer 2 by roller coating under the conditions of coating roller speed of 15 r / min and coating pressure of 0.6 MPa, and dry it at 90℃ for 3 h after coating to obtain the composite substrate with functional layer 3;

[0064] The mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent (nano silver), moisture-proofing agent (montmorillonite), and dispersant (sodium dodecylbenzenesulfonate) is 55:30:5:8:2.

[0065] 7. Prepare water-based ink according to the ratio, perform corona treatment on the upper surface of functional layer 3, and then print the water-based ink on the upper surface of functional layer 3 by gravure printing. After printing, dry at 70°C for 1 hour to obtain a composite substrate with printed decorative layer 4.

[0066] In the prepared water-based ink, the mass ratio of styrene-methyl methacrylate resin, pigment (titanium dioxide), water, leveling agent (BYK-307), anti-migration agent (polyethylene wax emulsion), and film-forming agent (dodecyl alcohol ester) is 30:12:50:1.5:2.5:4.

[0067] 8. Weigh the epoxy acrylate resin, phenyl vinyl silicone resin, compatibilizer (polyethylene grafted maleic anhydride), abrasion resistant agent (nano alumina), photoinitiator (2,2-dimethylolpropionic acid), and anti-yellowing agent (2,4-dihydroxybenzophenone) according to the specified proportions, add them to a mixing device, and stir at 250 rpm for 25 minutes to obtain a second mixture. Apply the second mixture to the upper surface of the printed decorative layer 4 by roller coating at a roller speed of 25 rpm and a coating pressure of 0.2 MPa. Then, cure it by UV irradiation with a wavelength of 365 nm and a curing energy of 800 mJ / cm². 2 A composite substrate with a surface protective layer 5 is obtained, namely the multi-layered environmentally friendly decorative paper; the mass ratio of the epoxy acrylate resin, phenyl vinyl silicone resin, compatibilizer (polyethylene grafted maleic anhydride), abrasion resistant agent (nano alumina), photoinitiator (2,2-dimethylolpropionic acid) and anti-yellowing agent (2,4-dihydroxybenzophenone) is 60:10:15:5:5:5.

[0068] The multi-layered environmentally friendly decorative paper prepared in this embodiment has a thickness of 120μm, wherein the thickness of the base layer 1 accounts for 40%, the thickness of the adhesive layer 2 accounts for 20%, the thickness of the functional layer 3 accounts for 20%, the thickness of the printed decorative layer 4 accounts for 10%, and the thickness of the surface protective layer 5 accounts for 10%.

[0069] Example 2

[0070] like Figure 2 As shown, a method for preparing a multi-layered environmentally friendly decorative paper includes the following steps:

[0071] 1. Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent (sodium carboxymethyl cellulose) and sizing agent (alkyl ketene dimer), stir at 500 rpm for 2 hours to make pulp for later use;

[0072] 2. The pulp is fed into a wire paper machine for papermaking. After two presses and dewatering, it is baked in hot air at 80°C for 4 hours. After cutting, the base layer 1 is obtained, in which the mass ratio of wood pulp fiber, bamboo pulp fiber, reinforcing agent (sodium carboxymethyl cellulose) and sizing agent (alkyl ketene dimer) is 40:50:5:5.

[0073] 3. Add ethyl acetate, polyurethane resin, and dried polyethylene glycol (obtained by drying at 120℃ for 3 hours, with a molecular weight of 2000) sequentially to the reaction vessel, purge with nitrogen, heat to 60℃, and stir at 300 rpm for 20 minutes to obtain a mixture.

[0074] 4. Add isocyanate-based propyltrimethoxysilane dropwise to the mixture, followed by the catalyst (dioctyltin dilaurate) and defoamer (polydimethylsiloxane), and heat to 70°C. Stir at 450 rpm for 2 hours, then add water and continue stirring for 60 minutes under the same conditions to obtain the reaction product. Continue to distill the reaction product under reduced pressure to obtain the modified polyurethane resin.

[0075] The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-based propyltrimethoxysilane, catalyst (dioctyltin dilaurate), defoamer (polydimethylsiloxane), and water is 50:30:10:2:0.1:1.9:6.

[0076] 5. The modified polyurethane resin is coated onto the upper surface of the prepared base layer 1 by roller coating at a coating roller speed of 30 r / min and a coating pressure of 0.5 MPa, and then dried at 90℃ for 1 h to obtain a composite substrate with adhesive layer 2.

[0077] 6. Weigh out polyacrylate resin, epoxy resin, antibacterial agent (nano zinc oxide), moisture-proof agent (bentonite), and dispersant (dodecyl acetate) according to the proportion, add them to the mixing equipment, and stir at 400 rpm for 20 min to obtain the first mixture; coat the first mixture onto the upper surface of the adhesive layer 2 by roller coating under the conditions of coating roller speed of 25 r / min and coating pressure of 0.8 MPa, and dry it at 100℃ for 2 h after coating to obtain the composite substrate with functional layer 3;

[0078] The mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent (nano zinc oxide), moisture-proofing agent (bentonite), and dispersant (dodecyl acetate) is 50:35:8:5:2.

[0079] 7. Prepare water-based ink according to the ratio, perform corona treatment on the upper surface of functional layer 3, and then print the water-based ink on the upper surface of functional layer 3 by gravure printing. After printing, dry at 80℃ for 0.5h to obtain a composite substrate with printed decorative layer 4.

[0080] In the prepared water-based ink, the mass ratio of styrene-methyl methacrylate resin, pigment (carbon black), water, leveling agent (BYK-327), anti-migration agent (polytetrafluoroethylene emulsion), and film-forming agent (polyvinyl acetate) is 20:15:60:0.1:0.9:4.

[0081] 8. Weigh out the polyurethane acrylate resin, acrylic silicone oil, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (nano-zirconia), photoinitiator (benzophenone), and anti-yellowing agent (2-hydroxy-4-methoxybenzophenone) according to the specified proportions, add them to a mixing device, and stir at 350 rpm for 15 min to obtain a second mixture. Apply the second mixture to the upper surface of the printed decorative layer 4 by roller coating under the conditions of a coating roller speed of 35 r / min and a coating pressure of 0.4 MPa. Then, cure it by UV irradiation with a wavelength of 425 nm and a curing energy of 1200 mJ / cm². 2 A composite substrate with a surface protective layer 5 is obtained, namely the multi-layered environmentally friendly decorative paper; the mass ratio of the polyurethane acrylate resin, acrylic silicone oil, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (nano-zirconia), photoinitiator (benzophenone), and anti-yellowing agent (2-hydroxy-4-methoxybenzophenone) is 50:25:10:5:5:5.

[0082] The multi-layered environmentally friendly decorative paper prepared in this embodiment has a thickness of 150μm, wherein the thickness of the base layer 1 accounts for 60%, the thickness of the adhesive layer 2 accounts for 10%, the thickness of the functional layer 3 accounts for 10%, the thickness of the printed decorative layer 4 accounts for 5%, and the thickness of the surface protective layer 5 accounts for 15%.

[0083] Example 3

[0084] like Figure 2 As shown, a method for preparing a multi-layered environmentally friendly decorative paper includes the following steps:

[0085] 1. Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent (polyacrylamide) and sizing agent (alkenyl succinic anhydride), and stir at 550 rpm for 1.5 hours to make pulp for later use;

[0086] 2. The pulp is fed into a wire paper machine for papermaking. After two presses and dewatering, it is baked in hot air at 75°C for 5 hours. After cutting, the base layer 1 is obtained, in which the mass ratio of wood pulp fiber, bamboo pulp fiber, reinforcing agent (polyacrylamide) and sizing agent (alkenyl succinic anhydride) is 50:42:5:3.

[0087] 3. Add ethyl acetate, polyurethane resin, and dried polyethylene glycol (obtained by drying at 110℃ for 3.5h, with a molecular weight of 1600) sequentially to the reaction vessel, purge with nitrogen, heat to 55℃, and stir at 250rpm for 30min to obtain a mixture.

[0088] 4. Add isocyanate-based propylmethyldimethoxysilane dropwise to the mixture, followed by the catalyst (stannous octoate) and defoamer (glyceryl monostearate), and heat to 65°C. Stir at 400 rpm for 2.5 h, then add water and continue stirring under the same conditions for 45 min to obtain the reaction product. Continue to distill the reaction product under reduced pressure to obtain the modified polyurethane resin.

[0089] The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-propylmethyldimethoxysilane, catalyst (stannous octoate), defoamer (glyceryl monostearate), and water is 42:33:12:4:0.3:2.7:6.

[0090] 5. The modified polyurethane resin is coated onto the upper surface of the prepared base layer 1 by roller coating at a coating roller speed of 25 r / min and a coating pressure of 0.4 MPa, and then dried at 85℃ for 1.5 h to obtain a composite substrate with adhesive layer 2.

[0091] 6. Weigh out polyacrylate resin, epoxy resin, antibacterial agent (nano copper oxide), moisture-proof agent (calcium chloride) and dispersant (sodium oleate) according to the proportion, add them to the mixing equipment, and stir at 350 rpm for 25 min to obtain the first mixture; coat the first mixture onto the upper surface of the adhesive layer 2 by roller coating under the conditions of coating roller speed of 20 r / min and coating pressure of 0.7 MPa, and dry it at 95℃ for 2.5 h after coating to obtain the composite substrate with functional layer 3;

[0092] The mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent (nano copper oxide), moisture-proofing agent (calcium chloride), and dispersant (sodium oleate) is 58:25:5.5:10:1.5.

[0093] 7. Prepare water-based ink according to the ratio, perform corona treatment on the upper surface of functional layer 3, and then print the water-based ink on the upper surface of functional layer 3 by gravure printing. After printing, dry at 75℃ for 0.8h to obtain a composite substrate with printed decorative layer 4.

[0094] In the prepared water-based ink, the mass ratio of styrene-methyl methacrylate resin, pigment (iron oxide red), water, leveling agent (BYK-329), anti-migration agent (polyamide wax), and film-forming agent (dipropylene glycol butyl ether) is 35:13:45:1:3:3;

[0095] 8. Weigh out the following components according to the specified proportions: polyester acrylate resin, methyl MQ silicone resin, compatibilizer (polyethylene grafted maleic anhydride), abrasion resistant agent (silicon carbide micro powder), photoinitiator (diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxide), and anti-yellowing agent (2-hydroxy-4-n-octyloxybenzophenone). Add these components to a mixing device and stir at 300 rpm for 20 minutes to obtain a second mixture. Apply the second mixture to the upper surface of the printed decorative layer 4 using a roller coating method at a coating roller speed of 30 rpm and a coating pressure of 0.3 MPa. Then, cure it by UV irradiation with a wavelength of 395 nm and a curing energy of 1000 mJ / cm². 2 A composite substrate with a surface protective layer 5 is obtained, namely the multi-layered environmentally friendly decorative paper; the mass ratio of the polyester acrylate resin, methyl MQ silicone resin, compatibilizer (polyethylene grafted maleic anhydride), abrasion resistant agent (silicon carbide micro powder), photoinitiator (diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxide) and anti-yellowing agent (2-hydroxy-4-n-octyloxybenzophenone) is 75:5:10:2:5:3.

[0096] The multi-layered environmentally friendly decorative paper prepared in this embodiment has a thickness of 200μm, wherein the thickness of the base layer 1 accounts for 50%, the thickness of the adhesive layer 2 accounts for 15%, the thickness of the functional layer 3 accounts for 15%, the thickness of the printed decorative layer 4 accounts for 15%, and the thickness of the surface protective layer 5 accounts for 5%.

[0097] Example 4

[0098] like Figure 2 As shown, a method for preparing a multi-layered environmentally friendly decorative paper includes the following steps:

[0099] 1. Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent (polyvinyl alcohol) and sizing agent (styrene-maleic anhydride copolymer), stir at 500 rpm for 2 hours to make pulp for later use;

[0100] 2. The pulp is fed into a wire paper machine for papermaking. After two presses and dewatering, it is baked in hot air at 80°C for 4 hours. After cutting, the base layer 1 is obtained, in which the mass ratio of wood pulp fiber, bamboo pulp fiber, reinforcing agent (polyvinyl alcohol) and sizing agent (styrene-maleic anhydride copolymer) is 48:48:2:2.

[0101] 3. Add ethyl acetate, polyurethane resin, and dried polyethylene glycol (obtained by drying at 100℃ for 4 hours, with a molecular weight of 2000) sequentially to the reaction vessel, purge with nitrogen, heat to 60℃, and stir at 200 rpm for 40 minutes to obtain a mixture.

[0102] 4. Add isocyanate-based methyltriethoxysilane dropwise to the mixture, followed by the catalyst (stannous octoate) and defoamer (glyceryl monostearate), and heat to 65°C. Stir at 450 rpm for 2 hours, then add water and continue stirring under the same conditions for 60 minutes to obtain the reaction product. Continue to distill the reaction product under reduced pressure to obtain the modified polyurethane resin.

[0103] The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-based methyltriethoxysilane, catalyst (stannous octoate), defoamer (glyceryl monostearate), and water is 40:32:15:2:0.5:1.5:9.

[0104] 5. The modified polyurethane resin is coated onto the upper surface of the prepared base layer 1 by roller coating at a coating roller speed of 30 r / min and a coating pressure of 0.3 MPa, and then dried at 90℃ for 1 h to obtain a composite substrate with adhesive layer 2.

[0105] 6. Weigh out polyacrylate resin, epoxy resin, antibacterial agent (isothiazolinone), moisture-proof agent (silicone) and dispersant (polyoxyethylene ether) according to the proportion, add them to the mixing equipment, and stir at 400 rpm for 20 min to obtain the first mixture; coat the first mixture onto the upper surface of the adhesive layer 2 by roller coating under the conditions of coating roller speed of 25 r / min and coating pressure of 0.6 MPa, and dry it at 100℃ for 2 h after coating to obtain the composite substrate with functional layer 3;

[0106] The mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent (isothiazolinone), moisture-proof agent (silicone) and dispersant (polyoxyethylene ether) is 60:25:3:10:2.

[0107] 7. Prepare water-based ink according to the ratio, perform corona treatment on the upper surface of functional layer 3, and then print the water-based ink on the upper surface of functional layer 3 by gravure printing. After printing, dry at 80℃ for 0.5h to obtain a composite substrate with printed decorative layer 4.

[0108] In the prepared water-based ink, the mass ratio of styrene-methyl methacrylate resin, pigment (ultramarine blue), water, leveling agent (BYK-361N), anti-migration agent (polyamide wax), and film-forming agent (dipropylene glycol butyl ether) is 40:10:40:1.5:0.5:8.

[0109] 8. Weigh the epoxy acrylate resin, methyl MQ silicone resin, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (polytetrafluoroethylene micro powder), photoinitiator (benzophenone), and anti-yellowing agent (2-hydroxy-4-methoxybenzophenone) according to the specified proportions, add them to the mixing equipment, and stir at 350 rpm for 15 min to obtain the second mixture; apply the second mixture to the upper surface of the printed decorative layer 4 by roller coating under the conditions of a coating roller speed of 35 r / min and a coating pressure of 0.2 MPa, and then cure it by UV irradiation with a wavelength of 425 nm and a curing energy of 800 mJ / cm. 2 A composite substrate with a surface protective layer 5 is obtained, namely the multi-layered environmentally friendly decorative paper; the mass ratio of the epoxy acrylate resin, methyl MQ silicone resin, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (polytetrafluoroethylene micro powder), photoinitiator (benzophenone) and anti-yellowing agent (2-hydroxy-4-methoxybenzophenone) is 55:20:12:3:7:3.

[0110] The multi-layered environmentally friendly decorative paper prepared in this embodiment has a thickness of 180μm, wherein the thickness of the base layer 1 accounts for 50%, the thickness of the adhesive layer 2 accounts for 10%, the thickness of the functional layer 3 accounts for 20%, the thickness of the printed decorative layer 4 accounts for 10%, and the thickness of the surface protective layer 5 accounts for 10%.

[0111] Example 5

[0112] like Figure 2 As shown, a method for preparing a multi-layered environmentally friendly decorative paper includes the following steps:

[0113] 1. Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent (nano silica) and sizing agent (alkenyl succinic anhydride), stir at 600 rpm for 1 hour to make pulp for later use;

[0114] 2. The pulp is fed into a wire paper machine for papermaking. After two presses and dewatering, it is baked in hot air at 70℃ for 6 hours. After cutting, the base layer 1 is obtained, in which the mass ratio of wood pulp fiber, bamboo pulp fiber, reinforcing agent (nano silica) and sizing agent (alkenyl succinic anhydride) is 48:46:4:2.

[0115] 3. Add ethyl acetate, polyurethane resin, and dried polyethylene glycol (obtained by drying at 120℃ for 3 hours, with a molecular weight of 1200) sequentially to the reaction vessel, purge with nitrogen, heat to 50℃, and stir at 300 rpm for 20 minutes to obtain a mixture.

[0116] 4. Add isocyanate-based propyltriethoxysilane dropwise to the mixture, followed by the catalyst (dibutyltin dilaurate) and defoamer (polyoxypropylene glycerol ether), and heat to 70°C. Stir at 350 rpm for 3 hours, then add water and continue stirring for 30 minutes under the same conditions to obtain the reaction product. Continue to distill the reaction product under reduced pressure to obtain the modified polyurethane resin.

[0117] The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-based propyltriethoxysilane, catalyst (dibutyltin dilaurate), defoamer (polyoxypropylene glycerol ether), and water is 42:32:10:6:0.2:2.8:7.

[0118] 5. The modified polyurethane resin is coated onto the upper surface of the prepared base layer 1 by roller coating at a coating roller speed of 20 r / min and a coating pressure of 0.5 MPa, and then dried at 80℃ for 2 h to obtain a composite substrate with adhesive layer 2.

[0119] 6. Weigh out polyacrylate resin, epoxy resin, antibacterial agent (chitosan), moisture-proofing agent (paraffin) and dispersant (fatty alcohol polyoxyethylene ether) according to the proportion, add them to the mixing equipment, and stir at 300 rpm for 30 min to obtain the first mixture; coat the first mixture onto the upper surface of the adhesive layer 2 by roller coating under the conditions of coating roller speed of 15 r / min and coating pressure of 0.8 MPa, and dry it at 90℃ for 3 h after coating to obtain the composite substrate with functional layer 3;

[0120] The mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent (chitosan), moisture-proofing agent (paraffin), and dispersant (fatty alcohol polyoxyethylene ether) is 52:34:6:6:2.

[0121] 7. Prepare water-based ink according to the ratio, perform corona treatment on the upper surface of functional layer 3, and then print the water-based ink on the upper surface of functional layer 3 by gravure printing. After printing, dry at 70°C for 1 hour to obtain a composite substrate with printed decorative layer 4.

[0122] In the prepared water-based ink, the mass ratio of styrene-methyl methacrylate resin, pigment (phthalocyanine blue), water, leveling agent (BYK-307), anti-migration agent (polyethylene wax emulsion), and film-forming agent (polyvinyl acetate) is 25:14:55:0.8:2.2:3.

[0123] 8. Weigh out the polyurethane acrylate resin, phenyl vinyl silicone resin, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (polyimide micro powder), photoinitiator (2,2-dimethylolpropionic acid), and anti-yellowing agent (2,4-dihydroxybenzophenone) according to the specified proportions, add them to a mixing device, and stir at 250 rpm for 25 min to obtain a second mixture. Apply the second mixture to the upper surface of the printed decorative layer 4 by roller coating at a coating roller speed of 25 r / min and a coating pressure of 0.4 MPa. Then, cure it by UV irradiation with a wavelength of 365 nm and a curing energy of 1200 mJ / cm². 2 A composite substrate with a surface protective layer 5 is obtained, namely the multi-layered environmentally friendly decorative paper; the mass ratio of the polyurethane acrylate resin, phenyl vinyl silicone resin, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (polyimide micro powder), photoinitiator (2,2-dimethylolpropionic acid) and anti-yellowing agent (2,4-dihydroxybenzophenone) is 65:15:10:2:5:3.

[0124] The multi-layered environmentally friendly decorative paper prepared in this embodiment has a thickness of 160μm, wherein the thickness of the base layer 1 accounts for 55%, the thickness of the adhesive layer 2 accounts for 15%, the thickness of the functional layer 3 accounts for 10%, the thickness of the printed decorative layer 4 accounts for 5%, and the thickness of the surface protective layer 5 accounts for 15%.

[0125] Example 6

[0126] like Figure 2 As shown, a method for preparing a multi-layered environmentally friendly decorative paper includes the following steps:

[0127] 1. Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent (nano-calcium carbonate) and sizing agent (alkyl ketene dimer), stir at 550 rpm for 1.8 hours to make pulp for later use;

[0128] 2. The pulp is fed into a wire paper machine for papermaking. After two presses and dewatering, it is baked in hot air at 78°C for 4.5 hours. After cutting, the base layer 1 is obtained, in which the mass ratio of wood pulp fiber, bamboo pulp fiber, reinforcing agent (nano-calcium carbonate) and sizing agent (alkyl ketene dimer) is 46:46:5:3.

[0129] 3. Add ethyl acetate, polyurethane resin, and dried polyethylene glycol (obtained by drying at 115℃ for 3.5h, with a molecular weight of 1800) sequentially to the reaction vessel, purge with nitrogen, heat to 56℃, and stir at 280rpm for 35min to obtain a mixture.

[0130] 4. Add isocyanate-based methyltrimethoxysilane dropwise to the mixture, followed by the catalyst (dioctyltin dilaurate) and defoamer (polydimethylsiloxane), and heat to 68°C. Stir at 400 rpm for 2.5 h, then add water and continue stirring for 50 min under the same conditions to obtain the reaction product. Continue to distill the reaction product under reduced pressure to obtain the modified polyurethane resin.

[0131] The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-based methyltrimethoxysilane, catalyst (dioctyltin dilaurate), defoamer (polydimethylsiloxane), and water is 41:32:11:5:0.4:2.6:8.

[0132] 5. The modified polyurethane resin is coated onto the upper surface of the prepared base layer 1 by roller coating at a coating roller speed of 25 r / min and a coating pressure of 0.45 MPa, and then dried at 85℃ for 1.5 h to obtain a composite substrate with adhesive layer 2.

[0133] 6. Weigh out polyacrylate resin, epoxy resin, antibacterial agent (tea polyphenols), moisture-proof agent (calcium chloride) and dispersant (sodium oleate) according to the proportion, add them to the mixing equipment, and stir at 360 rpm for 25 min to obtain the first mixture; coat the first mixture onto the upper surface of the adhesive layer 2 by roller coating under the conditions of coating roller speed of 18 r / min and coating pressure of 0.75 MPa, and dry it at 95℃ for 2 h after coating to obtain the composite substrate with functional layer 3;

[0134] The mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent (tea polyphenols), moisture-proofing agent (calcium chloride), and dispersant (sodium oleate) is 56:28:6:9:1.

[0135] 7. Prepare water-based ink according to the ratio, perform corona treatment on the upper surface of functional layer 3, and then print the water-based ink on the upper surface of functional layer 3 by gravure printing. After printing, dry at 75°C for 0.5 hours to obtain a composite substrate with printed decorative layer 4.

[0136] In the prepared water-based ink, the mass ratio of styrene-methyl methacrylate resin, pigment (ultramarine blue), water, leveling agent (BYK-329), anti-migration agent (polytetrafluoroethylene emulsion), and film-forming agent (polyvinyl acetate) is 32:11:48:1.2:2.8:5.

[0137] 8. Weigh out the following components according to the specified proportions: polyester acrylate resin, acrylic silicone oil, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (nano-zirconia), photoinitiator (benzophenone), and anti-yellowing agent (2-hydroxy-4-methoxybenzophenone). Add these components to a mixing device and stir at 300 rpm for 20 minutes to obtain a second mixture. Apply the second mixture to the upper surface of the printed decorative layer 4 using a roller coating method at a coating roller speed of 30 rpm and a coating pressure of 0.35 MPa. Then, cure it by UV irradiation with a wavelength of 405 nm and a curing energy of 950 mJ / cm². 2 A composite substrate with a surface protective layer 5 is obtained, namely the multi-layered environmentally friendly decorative paper; the mass ratio of the polyester acrylate resin, acrylic silicone oil, compatibilizer (polypropylene grafted maleic anhydride), abrasion resistant agent (nano zirconium oxide), photoinitiator (benzophenone) and anti-yellowing agent (2-hydroxy-4-methoxybenzophenone) is 62:18:12:4:3:1.

[0138] The multi-layered environmentally friendly decorative paper prepared in this embodiment has a thickness of 200μm, wherein the thickness of the base layer 1 accounts for 45%, the thickness of the adhesive layer 2 accounts for 20%, the thickness of the functional layer 3 accounts for 15%, the thickness of the printed decorative layer 4 accounts for 10%, and the thickness of the surface protective layer 5 accounts for 10%.

[0139] Comparative Example 1

[0140] This comparative example provides a method for preparing a multi-layered environmentally friendly decorative paper. The difference from Example 1 is that the multi-layered environmentally friendly decorative paper prepared in this comparative example does not have an adhesive layer 2. Other process parameters and operating steps are exactly the same as in Example 1.

[0141] Comparative Example 2

[0142] This comparative example provides a method for preparing a multi-layered environmentally friendly decorative paper. The difference from Example 1 is that the polyurethane resin used in the adhesive layer 2 of the multi-layered environmentally friendly decorative paper prepared in this comparative example has not been modified, while other process parameters and operating steps are exactly the same as in Example 1.

[0143] Comparative Example 3

[0144] This comparative example provides a method for preparing a multi-layered environmentally friendly decorative paper. The difference from Example 1 is that the multi-layered environmentally friendly decorative paper prepared in this comparative example does not have a surface protective layer 5. Other process parameters and operating steps are exactly the same as in Example 1.

[0145] Comparative Example 4

[0146] This comparative example provides a method for preparing a multi-layered environmentally friendly decorative paper. The difference from Example 1 is that the ink used for printing the decorative layer 4 in the multi-layered environmentally friendly decorative paper prepared in this comparative example is not water-based ink. Other process parameters and operating steps are exactly the same as in Example 1.

[0147] The abrasion resistance of the multi-layered environmentally friendly decorative paper was demonstrated by testing its abrasion resistance revolutions; the interlayer bonding strength was demonstrated by testing its interlayer peel strength; and its environmental protection effect was demonstrated by testing its free formaldehyde release. The test results of the multi-layered environmentally friendly decorative paper prepared in each embodiment and comparative example are statistically shown in Table 1.

[0148] Table 1. Test results of the multilayer environmentally friendly decorative paper prepared in the examples and comparative examples.

[0149]

[0150] As shown in Table 1, the overall performance of the multi-layered environmentally friendly decorative paper prepared in Examples 1-6 is better than that of the multi-layered environmentally friendly decorative paper prepared in Comparative Examples 1-4.

[0151] The main reason is that in the multi-layered environmentally friendly decorative paper prepared in this application, the wood pulp fiber and bamboo pulp fiber used in the base layer 1 are biomass conversion materials. With the cooperation of reinforcing agents and sizing agents, they interweave to form a stable and environmentally friendly fiber skeleton through the papermaking process, providing basic support strength for the overall environmentally friendly decorative paper. Secondly, polyurethane resin and polyethylene glycol are compounded together by isocyanate silane coupling agent to form a modified polyurethane resin rich in oxygen-containing and nitrogen-containing groups. This modified polyurethane resin serves as the adhesive layer 2, possessing both high adhesion and flexibility. It can eliminate the interfacial stress between the adhesive layer 2 and the base layer 1 and functional layer 3, strengthen the interlayer bonding strength of the adhesive layer 2, base layer 1, and functional layer 3, and prevent delamination. In addition, the functional layer 3 uses polyacrylate resin and epoxy resin composite as the matrix, which has good weather resistance and corrosion resistance, and is also rich in oxygen-containing groups, making it compatible with the adhesive layer 2. At the same time, its composition also includes antibacterial and moisture-proof additives, achieving dual functions of antibacterial and mildew-proof as well as moisture-proof, which can further extend the service life of the prepared environmentally friendly decorative paper. Furthermore, the water-based ink used in the printed decorative layer 4 employs styrene-methyl methacrylate resin as a binder, which can match the polyacrylate and epoxy resin of the functional layer 3, enhancing interlayer adhesion. The water-based ink uses water as a solvent, avoiding VOC emissions from organic solvents while ensuring the clarity of the decorative pattern. Finally, the surface protective layer 5 is formed by the co-curing of UV-cured resin and silicone resin to create a dense protective layer. While tightly adhering to the printed decorative layer 4, it incorporates anti-yellowing and abrasion-resistant components to isolate it from various external physical or chemical erosions, significantly extending the service life of the multi-layered environmentally friendly decorative paper.

[0152] In contrast, Comparative Example 1 lacks an adhesive layer 2, which fails to enhance the interlayer bond strength between the adhesive layer 2, the base layer 1, and the functional layer 3, resulting in the lowest interlayer peel strength.

[0153] Although Comparative Example 2 has an adhesive layer 2, the polyurethane resin used has not been modified and ultimately cannot generate silanol groups through a series of reactions to further react with the hydroxyl groups on the surface of the base layer 1 and the functional layer 3 to form siloxane bonds. Therefore, the interfacial bonding force is significantly reduced and the interlayer peel strength is low.

[0154] In Comparative Example 3, there was no surface protective layer 5, and no UV-curable resin and silicone resin were cured together to form a dense protective layer, resulting in a significant decrease in wear resistance.

[0155] The ink used in Comparative Example 4 was not water-based, making it difficult to avoid the emission of organic solvent VOCs, resulting in the highest release of free formaldehyde.

[0156] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0157] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A multi-layered environmentally friendly decorative paper, characterized in that, The product comprises, from bottom to top, a base layer (1), an adhesive layer (2), a functional layer (3), a printed decorative layer (4), and a surface protective layer (5) that are bonded together. The base layer (1) is made of wood pulp fiber, bamboo pulp fiber, reinforcing agent, and sizing agent. The adhesive layer (2) is a modified polyurethane resin. The functional layer (3) includes polyacrylate resin, epoxy resin, antibacterial agent, moisture-proof agent, and dispersant. The printed decorative layer (4) is a water-based ink. The surface protective layer (5) includes UV-curable resin, silicone resin, compatibilizer, abrasion resistant agent, photoinitiator, and anti-yellowing agent.

2. The multi-layered environmentally friendly decorative paper according to claim 1, characterized in that, The thickness of this multi-layered environmentally friendly decorative paper is 120-200μm, of which the thickness of the base layer (1) accounts for 40-60%, the thickness of the adhesive layer (2) accounts for 10-20%, the thickness of the functional layer (3) accounts for 10-20%, the thickness of the printed decorative layer (4) accounts for 5-15%, and the thickness of the surface protective layer (5) accounts for 5-15%.

3. The multi-layered environmentally friendly decorative paper according to claim 1, characterized in that, In the base layer (1), the mass ratio of wood pulp fiber, bamboo pulp fiber, reinforcing agent and sizing agent is (40-50): (40-50): (2-5): (1-5).

4. The multi-layered environmentally friendly decorative paper according to claim 1, characterized in that, In the adhesive layer (2), the modified polyurethane resin is prepared by the following method: Ethyl acetate, polyurethane resin, and dried polyethylene glycol were added sequentially to the reactor. Nitrogen gas was purged for protection, and the temperature was raised to 50-60℃. The mixture was stirred at 200-300 rpm for 20-40 minutes to obtain a mixture. Isocyanate-based silane coupling agent is added dropwise to the mixture, followed by catalyst and defoamer, and the temperature is raised to 65-70℃. The mixture is stirred at 350-450 rpm for 2-3 hours, then water is added, and stirring is continued for 30-60 minutes under the same conditions to obtain the reaction product. The modified polyurethane resin is obtained by vacuum distillation of the reaction product. The mass ratio of ethyl acetate, polyurethane resin, dried polyethylene glycol, isocyanate-based silane coupling agent, catalyst, defoamer and water is (40-50): (30-40): (10-15): (2-6): (0.1-0.5): (1-3): (5-10).

5. The multi-layered environmentally friendly decorative paper according to claim 4, characterized in that, The dried polyethylene glycol is obtained by drying polyethylene glycol at 100-120℃ for 3-4 hours, and its molecular weight is 1200-2000.

6. The multi-layered environmentally friendly decorative paper according to claim 4, characterized in that, The isocyanate-based silane coupling agent includes any one or more of isocyanate-based methyltrimethoxysilane, isocyanate-based propyltrimethoxysilane, isocyanate-based propylmethyldimethoxysilane, isocyanate-based methyltriethoxysilane, and isocyanate-based propyltriethoxysilane.

7. The multi-layered environmentally friendly decorative paper according to claim 1, characterized in that, In the functional layer (3), the mass ratio of the polyacrylate resin, epoxy resin, antibacterial agent, moisture-proof agent and dispersant is (50-60): (25-35): (2-8): (3-10): (1-2).

8. The multi-layered environmentally friendly decorative paper according to claim 1, characterized in that, In the printed decorative layer (4), the water-based ink comprises styrene-methyl methacrylate resin, pigment, water, leveling agent, anti-migration agent and film-forming agent; the mass ratio of styrene-methyl methacrylate resin, pigment, water, leveling agent, anti-migration agent and film-forming agent is (20-40): (10-15): (40-60): (0.1-1.5): (0.5-3): (2-8).

9. The multi-layered environmentally friendly decorative paper according to claim 1, characterized in that, In the surface protective layer (5), the mass ratio of the UV-curable resin, silicone resin, compatibilizer, abrasion resistant agent, photoinitiator and anti-yellowing agent is (50-75):(5-25):(10-15):(1-10):(1-8):(1-5); the UV-curable resin includes any one or more of epoxy acrylate resin, polyurethane acrylate resin and polyester acrylate resin; the silicone resin includes any one or more of phenyl vinyl silicone resin, acrylic silicone oil and methyl MQ silicone resin.

10. A method for preparing a multi-layered environmentally friendly decorative paper, used to prepare the multi-layered environmentally friendly decorative paper as described in any one of claims 1-9, characterized in that, Includes the following steps: Add wood pulp fiber and bamboo pulp fiber to a pulper containing water in proportion, then add reinforcing agent and sizing agent, and stir at 500-600 rpm for 1-2 hours to make pulp for later use. The pulp is fed into a wire paper machine for papermaking, and after two presses to dewater it, it is baked in hot air at 70-80℃ for 4-6 hours. After cutting, the base layer is obtained (1). The modified polyurethane resin was coated onto the upper surface of the prepared base layer (1) by roller coating under the conditions of a coating roller speed of 20-30 r / min and a coating pressure of 0.3-0.5 MPa. Then it was dried at 80-90℃ for 1-2 h to obtain a composite substrate with an adhesive layer (2). Weigh out polyacrylate resin, epoxy resin, antibacterial agent, moisture-proof agent and dispersant according to the proportion, add them to the mixing equipment, stir at 300-400 rpm for 20-30 min to obtain the first mixture; coat the first mixture onto the upper surface of the adhesive layer (2) by roller coating under the conditions of coating roller speed of 15-25 r / min and coating pressure of 0.6-0.8 MPa, and dry it at 90-100℃ for 2-3 h after coating to obtain a composite substrate with functional layer (3); Water-based ink is prepared according to the proportion. After corona treatment of the upper surface of the functional layer (3), the water-based ink is printed on the upper surface of the functional layer (3) by gravure printing. After printing, it is dried at 70-80℃ for 0.5-1h to obtain a composite substrate with a printed decorative layer (4). Weigh out the UV-curable resin, silicone resin, compatibilizer, abrasion resistant agent, photoinitiator, and anti-yellowing agent according to the proportion, add them to the mixing equipment, and stir at 250-350 rpm for 15-25 min to obtain the second mixture; apply the second mixture to the upper surface of the printed decorative layer (4) by roller coating under the conditions of a coating roller speed of 25-35 r / min and a coating pressure of 0.2-0.4 MPa, and then cure it by UV irradiation with a wavelength of 365-425 nm and a curing energy of 800-1200 mJ / cm. 2 A composite substrate with a surface protective layer (5) is obtained, namely the multi-layered environmentally friendly decorative paper.

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