High-air-permeability high-temperature-resistant digital printing decorative base paper and preparation method thereof

Abstract

The invention discloses high-air-permeability high-temperature-resistant digital printing decorative base paper and a preparation method thereof, and belongs to the field of paper sheet manufacturing, and the preparation method comprises the following steps: preparing high-temperature-resistant resin emulsion, preparing composite nano silicon dioxide, preparing in-machine coating functional coating liquid, and coating; the preparation of the high-temperature-resistant resin emulsion comprises the following steps: mixing water-based resin and silica sol, uniformly stirring to obtain a mixed solution, mixing the mixed solution with casein and water, and uniformly stirring to obtain the high-temperature-resistant resin emulsion. According to the preparation method disclosed by the invention, the specially modified resin, the functional additive and the filler are adopted for in-machine coating, so that the effects of relatively good air permeability and high temperature resistance can be achieved, and the flatness of the decorative base paper is high.

Description

Technical Field

[0001] This invention relates to the field of paper manufacturing, specifically to a highly breathable, high-temperature resistant digital printing decorative base paper and its preparation method. Background Technology

[0002] In the fields of modern architectural decoration and furniture manufacturing, decorative base paper plays an indispensable role as a key material for veneer on engineered wood panels. Made primarily from high-quality wood pulp and titanium dioxide through a special process, it possesses numerous excellent properties such as heat insulation, flame retardancy, non-warping, non-cracking, easy cleaning, low cost, and environmental friendliness. It is widely used in the interior decoration of hotels, shopping malls, office buildings, homes, and transportation vehicles, representing an environmentally friendly material that "replaces plastic with paper and wood with paper." Based on different functions, decorative base paper can be subdivided into four types: surface protective base paper, top decorative base paper, bottom balancing base paper, and other base papers, each undertaking important functions such as enhancing wear resistance, decorative aesthetics, and moisture balance.

[0003] Traditional decorative paper printing techniques, such as gravure printing, are gradually revealing their limitations in the face of today's diversified market demands. With socio-economic development and rising consumer aesthetic standards, the demand for personalized and diversified decorative materials is increasing. Consumers are no longer satisfied with uniform decorative styles, but instead seek decorative products that reflect unique taste and personality. Traditional printing techniques suffer from high costs and long production cycles when handling small-batch, multi-variety orders, making it difficult to respond quickly to market changes and fully meet consumers' pursuit of decorative effects and personalization.

[0004] The emergence of digital printing technology has brought new development opportunities to the decorative base paper industry. With its high precision, flexibility, and efficiency, it can accurately present complex patterns and personalized designs. Through digital printing, designers can transform various creative ideas and inspirations into exquisite decorative patterns. Whether it's delicate wood grain, realistic stone textures, or unique artistic patterns, they can all be perfectly presented on decorative base paper, providing endless possibilities for enhancing decorative effects. Digital printing technology can also quickly adjust design schemes according to customers' personalized needs, achieving customized production and greatly satisfying the market's demand for personalized decorative products.

[0005] From an industry development perspective, the application of digital printing technology is a significant manifestation of technological innovation and upgrading in the decorative base paper industry. It has driven changes in decorative base paper production processes, prompting companies to continuously research and improve related technologies, thereby enhancing production efficiency and product quality.

[0006] Currently, while existing substrate layers composed of resin and fillers offer significant advantages in printing accuracy, color reproduction, and flexibility for small-batch production, they suffer from the following problems: First, the use of resin reduces the paper's air permeability, resulting in a slower resin impregnation speed for digital printing decorative base paper compared to traditional printing methods. Second, the resin's poor temperature resistance means that the resulting digital printing decorative base paper also suffers from slower platen temperature resistance compared to traditional printing methods, limiting the efficiency of subsequent resin impregnation and hot pressing. Third, the fillers have small particle sizes, high surface energy, and are prone to agglomeration, leading to an uneven substrate layer. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a highly breathable and high-temperature resistant digital printing decorative base paper and its preparation method. By using specially modified resins, functional additives, and fillers for in-machine coating, good breathability and high-temperature resistance can be achieved, and the decorative base paper also has high flatness.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a highly breathable and high-temperature resistant digital printing decorative base paper includes: preparing a high-temperature resistant resin emulsion, preparing a composite nano-silica, preparing an in-machine coating functional coating liquid, and coating. The preparation of the high-temperature resistant resin emulsion involves mixing an aqueous resin with silica sol, stirring until homogeneous, obtaining a mixed solution, and then mixing the mixed solution with casein and water, stirring until homogeneous to obtain the high-temperature resistant resin emulsion. In the preparation of the high-temperature resistant resin emulsion, the mass ratio of aqueous resin to silica sol is 1:3-3.3. The ratio of the mixed solution to casein by oven-dry mass is 1-1.2:1; The aqueous resin is one of acrylic resin emulsion, polyurethane resin emulsion, and polyvinyl alcohol resin particles; The acrylic resin emulsion is an aqueous acrylic styrene copolymer resin emulsion with a solid content of 41-43% and a number average molecular weight of 4000-6000. The polyurethane resin emulsion is an aqueous polyurethane resin emulsion with a solid content of 29-31% and a number average molecular weight of 5000-8000. The polyvinyl alcohol resin particles are polyvinyl alcohol 1788 resin particles. The solid content of the high-temperature resistant resin emulsion is 14-16%; The preparation of composite nano-silica involves mixing tetraethyl orthosilicate with anhydrous ethanol and stirring until homogeneous to obtain solution A. Zinc oxide, Tween-80, water, and anhydrous ethanol are mixed and stirred until homogeneous. The mixture is then sonicated at 20-30 kHz for 30-40 minutes. Polyvinylpyrrolidone is added and stirred until homogeneous. The mixture is then sonicated at 20-30 kHz for 30-40 minutes. Ammonia is added and stirred until homogeneous to obtain solution B. Solution B is stirred at room temperature while solution A is added dropwise. After the addition is complete, stirring continues for 1.5-2 hours. The mixture is then centrifuged at 14000-16000 rpm for 15-20 minutes. The precipitate is collected, washed 3-4 times with anhydrous ethanol, washed 3-4 times with water, and dried. It is then mixed with an aqueous zinc sulfate solution and stirred for 1-2 hours. The mixture is then centrifuged at 14000-16000 rpm for 15-20 minutes. The precipitate is collected, washed 3-4 times with water, and dried to obtain composite nano-silica. In the preparation of the composite nano silica, the volume ratio of tetraethyl orthosilicate to anhydrous ethanol in solution A is 30-35:400-450. In solution B, the ratio of zinc oxide, Tween-80, water, anhydrous ethanol, polyvinylpyrrolidone, and ammonia is 4.7-5g:1.5-1.7g:70-80mL:370-400mL:1.5-1.7g:20-23mL. The ratio of tetraethyl orthosilicate in solution A, zinc oxide in solution B, and zinc sulfate aqueous solution is 30-35 mL: 4.7-5 g: 400-500 mL; The average particle size of the zinc oxide is 30 nm; The mass concentration of the ammonia solution is 25%. The zinc sulfate aqueous solution has a mass concentration of 5%; The dropping time for solution A is 2-2.5 hours; The preparation of the in-machine functional coating liquid involves mixing high-temperature resistant resin emulsion, composite nano silica, and functional additives, stirring until uniform, and then mixing the mixture with water and stirring until uniform to obtain the in-machine functional coating liquid. In the functional coating liquid prepared by the machine, the oven-dry mass ratio of high-temperature resistant resin emulsion, composite nano silica, and functional additives is 20-23:75-80:5-5.2. The mass ratio of the mixture to water is 1:4-4.2; The functional additive is a mixture of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer, wherein the mass ratio of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer is 5-5.4:4-4.3:1; The coating process involves semi-wet calendering the base paper, followed by coating with an in-machine coating liquid, and drying after coating to obtain a highly breathable and high-temperature resistant digital printing decorative base paper. In the coating process, the coating amount of the in-machine coating functional coating liquid is 3-8 g / m³. 2 ; The basis weight of the base paper is 80-100 g / m². 2 ; During coating, the coating is performed using a film transfer applicator.

[0009] A highly permeable, high-temperature resistant digital printing decorative base paper prepared by the aforementioned preparation method.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The preparation method of digital printing decorative base paper of the present invention can make the ink quickly penetrate into the paper and fully combine and fix with the paper fibers, presenting a good color reproduction. At the same time, it can have a small impact on the air permeability after printing on the base paper, ensuring that the glue impregnation speed is better than that of general digital printing decorative paper. (2) The method for preparing digital printing decorative base paper of the present invention involves adding silica sol and casein to water-based resin. The silica sol and water-based resin can condense into sol resin particles. Casein can effectively improve dispersion stability and film-forming efficiency. It can quickly form a secondary mullite network structure at high temperature, thereby improving the high temperature resistance of the prepared digital printing decorative base paper. This solves the limitation of temperature increase during impregnation and pressing, and can also improve the flatness of the prepared digital printing decorative base paper. (3) By using composite nano-silica combined with high-temperature resistant resin emulsion, the present invention can improve the printing gloss and coating structure performance, which can improve the paper printing effect and reduce the impact of printing on the paper air permeability. (4) In this invention, high-temperature resistant silica sol and casein are added to the digital printing coating to modify it, so that it has high-temperature resistance. At the same time, composite nano silica with uniform particle size is combined to improve the structural performance of the functional coating, so that the prepared digital printing decorative base paper has good air permeability and high-temperature resistance. (5) In the preparation of composite nano silica, the present invention first mixes Tween-80 with nano-sized zinc oxide to promote the uniform dispersion of nano-sized zinc oxide, and then mixes it with polyvinylpyrrolidone. Polyvinylpyrrolidone can bind tetraethyl orthosilicate. Tetraethyl orthosilicate hydrolyzes under alkaline conditions to form porous silica on the surface of zinc oxide. Then, it is treated with zinc sulfate aqueous solution. Zinc sulfate is adsorbed on the surface of porous silica to obtain composite nano silica. Composite nano silica can be used as a porous filler to improve the air permeability and high temperature resistance of the prepared digital printing decorative base paper. (6) The digital printing decorative base paper of the present invention has good air permeability, high temperature resistance and flatness. When printing on the digital printing decorative base paper of the present invention, the air permeability of the red color block area is 28-30s and the color density is 1.06-1.09, and the air permeability of the black color block area is 34-37s and the color density is 1.25-1.29. After printing on the digital printing decorative base paper of the present invention, after soaking at room temperature for 1 hour, the color density retention rate of the red color block area is 97.91-99.52% and the color density retention rate of the black color block area is 95.48-98.43%. When the digital printing decorative base paper of the present invention is impregnated with glue, the glue amount in 10s is 125-128%, and the pressing effect is qualified. The dynamic friction coefficient of the digital printing decorative base paper of the present invention is 0.302-0.315 and the static friction coefficient is 0.258-0.267. Detailed Implementation

[0011] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0012] Example 1 A method for preparing digital printing decorative base paper is as follows: 1. Preparation of high-temperature resistant resin emulsion: Aqueous resin and silica sol are mixed at a mass ratio of 1:3 and stirred evenly to obtain a mixed solution. The mixed solution is then mixed with casein and water, and the oven-dry mass ratio of the mixed solution to casein is controlled at 1:1. The mixture is stirred evenly to obtain a high-temperature resistant resin emulsion with a solid content of 14%. The aqueous resin is an acrylic resin emulsion; The acrylic resin emulsion is an aqueous acrylic styrene copolymer resin emulsion with a solid content of 42% and a number average molecular weight of 5000. 2. Preparation of composite nano-silica: Mix 30 mL of tetraethyl orthosilicate with 400 mL of anhydrous ethanol and stir until homogeneous to obtain solution A; mix 4.7 g of zinc oxide, 1.5 g of Tween-80, 70 mL of water, and 370 mL of anhydrous ethanol and stir until homogeneous. Sonicate at 20 kHz for 30 min, add 1.5 g of polyvinylpyrrolidone, stir until homogeneous, sonicate at 20 kHz for 30 min, add 20 mL of ammonia water, and stir until homogeneous to obtain solution B; stir all of the above solution B at room temperature, and simultaneously add all of the above solution A dropwise, controlling the dropwise addition time to 2 h. After the dropwise addition is completed, continue stirring for 1.5 h, centrifuge at 14000 rpm for 15 min, collect the precipitate, wash 3 times with anhydrous ethanol, wash 3 times with water, dry, then mix with 400 mL of zinc sulfate aqueous solution, stir for 1 h, centrifuge at 14000 rpm for 15 min, collect the precipitate, wash 3 times with water, and dry to obtain composite nano-silica; The average particle size of the zinc oxide is 30 nm; The mass concentration of the ammonia solution is 25%. The zinc sulfate aqueous solution has a mass concentration of 5%; 3. Preparation of in-machine functional coating liquid: Mix high temperature resistant resin emulsion, composite nano silica and functional additives at an oven-dry mass ratio of 20:75:5, stir evenly to obtain a mixture, mix the mixture with water at a mass ratio of 1:4, stir evenly to obtain the in-machine functional coating liquid. The functional additive is a mixture of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer, wherein the mass ratio of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer is 5:4:1. 4. Coating: After semi-wet calendering of the base paper, coating is performed using an in-machine coating liquid through a film transfer sizing machine, controlling the coating amount to 4g / m². 2 After coating, the paper is dried to obtain a highly breathable and high-temperature resistant digital printing decorative base paper. The basis weight of the base paper is 85 g / m². 2 .

[0013] This embodiment also provides a digital printing decorative base paper prepared by the aforementioned preparation method.

[0014] Example 2 A method for preparing digital printing decorative base paper is as follows: 1. Preparation of high-temperature resistant resin emulsion: Aqueous resin and silica sol are mixed at a mass ratio of 1:3.1 and stirred evenly to obtain a mixed solution. The mixed solution is then mixed with casein and water, and the oven-dry mass ratio of the mixed solution to casein is controlled at 1.1:1. The mixture is stirred evenly to obtain a high-temperature resistant resin emulsion with a solid content of 15%. The aqueous resin is a polyurethane resin emulsion; The polyurethane resin emulsion is an aqueous polyurethane resin emulsion with a solid content of 30% and a number average molecular weight of 5000. 2. Preparation of composite nano-silica: Mix 32 mL of tetraethyl orthosilicate with 420 mL of anhydrous ethanol and stir until homogeneous to obtain solution A; mix 4.8 g of zinc oxide, 1.6 g of Tween-80, 75 mL of water, and 380 mL of anhydrous ethanol and stir until homogeneous. Sonicate at 20 kHz for 30 min, add 1.6 g of polyvinylpyrrolidone, stir until homogeneous, sonicate at 20 kHz for 30 min, add 21 mL of ammonia water, and stir until homogeneous to obtain solution B; stir all of the above solution B at room temperature, and simultaneously add all of the above solution A dropwise, controlling the dropwise addition time to 2 h. After the dropwise addition is completed, continue stirring for 1.5 h, centrifuge at 14000 rpm for 16 min, collect the precipitate, wash 3 times with anhydrous ethanol, wash 3 times with water, dry, then mix with 420 mL of zinc sulfate aqueous solution, stir for 1.5 h, centrifuge at 15000 rpm for 16 min, collect the precipitate, wash 3 times with water, and dry to obtain composite nano-silica; The average particle size of the zinc oxide is 30 nm; The mass concentration of the ammonia solution is 25%. The zinc sulfate aqueous solution has a mass concentration of 5%; 3. Preparation of in-machine functional coating liquid: Mix high temperature resistant resin emulsion, composite nano silica and functional additives at an oven-dry mass ratio of 21:76:5.1, stir evenly to obtain a mixture, mix the mixture with water at a mass ratio of 1:4.1, stir evenly to obtain the in-machine functional coating liquid; The functional additive is a mixture of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer, wherein the mass ratio of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer is 5.1:4.2:1; 4. Coating: After semi-wet calendering of the base paper, coating is performed using an in-machine coating liquid through a film transfer sizing machine, controlling the coating amount to 5g / m². 2 After coating, the paper is dried to obtain a highly breathable and high-temperature resistant digital printing decorative base paper. The basis weight of the base paper is 85 g / m². 2 .

[0015] This embodiment also provides a digital printing decorative base paper prepared by the aforementioned preparation method.

[0016] Example 3 A method for preparing digital printing decorative base paper is as follows: 1. Preparation of high-temperature resistant resin emulsion: Aqueous resin and silica sol are mixed at a mass ratio of 1:3.2 and stirred evenly to obtain a mixed solution. The mixed solution is then mixed with casein and water, and the oven-dry mass ratio of the mixed solution to casein is controlled at 1.1:1. The mixture is stirred evenly to obtain a high-temperature resistant resin emulsion with a solid content of 15%. The aqueous resin is polyvinyl alcohol resin particles; The polyvinyl alcohol resin particles are polyvinyl alcohol 1788 resin particles. 2. Preparation of composite nano-silica: Mix 34 mL of tetraethyl orthosilicate with 430 mL of anhydrous ethanol and stir until homogeneous to obtain solution A; mix 4.9 g of zinc oxide, 1.6 g of Tween-80, 75 mL of water, and 390 mL of anhydrous ethanol and stir until homogeneous. Sonicate at 25 kHz for 35 min, add 1.6 g of polyvinylpyrrolidone, stir until homogeneous, sonicate at 25 kHz for 35 min, add 22 mL of ammonia water, and stir until homogeneous to obtain solution B; stir all of the above solution B at room temperature, and simultaneously add all of the above solution A dropwise, controlling the dropwise addition time to 2 h. After the dropwise addition is completed, continue stirring for 1.5 h, centrifuge at 16000 rpm for 20 min, collect the precipitate, wash 4 times with anhydrous ethanol, wash 4 times with water, dry, then mix with 450 mL of zinc sulfate aqueous solution, stir for 2 h, centrifuge at 16000 rpm for 20 min, collect the precipitate, wash 4 times with water, and dry to obtain composite nano-silica; The average particle size of the zinc oxide is 30 nm; The mass concentration of the ammonia solution is 25%. The zinc sulfate aqueous solution has a mass concentration of 5%; 3. Preparation of in-machine functional coating liquid: Mix high temperature resistant resin emulsion, composite nano silica and functional additives at an oven-dry mass ratio of 22:78:5.1, stir evenly to obtain a mixture, mix the mixture with water at a mass ratio of 1:4.1, stir evenly to obtain the in-machine functional coating liquid; The functional additive is a mixture of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer, wherein the mass ratio of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer is 5.3:4.3:1; 4. Coating: After semi-wet calendering of the base paper, coating is performed using an in-machine coating liquid through a film transfer sizing machine, controlling the coating amount to 5.5 g / m². 2 After coating, the paper is dried to obtain a highly breathable and high-temperature resistant digital printing decorative base paper. The basis weight of the base paper is 85 g / m². 2 .

[0017] This embodiment also provides a digital printing decorative base paper prepared by the aforementioned preparation method.

[0018] Example 4 A method for preparing digital printing decorative base paper is as follows: 1. Preparation of high-temperature resistant resin emulsion: Aqueous resin and silica sol are mixed at a mass ratio of 1:3.3 and stirred evenly to obtain a mixed solution. The mixed solution is then mixed with casein and water, and the oven-dry mass ratio of the mixed solution to casein is controlled at 1.2:1. The mixture is stirred evenly to obtain a high-temperature resistant resin emulsion with a solid content of 15%. The aqueous resin is an acrylic resin emulsion; The acrylic resin emulsion is an aqueous acrylic styrene copolymer resin emulsion with a solid content of 42% and a number average molecular weight of 5000. 2. Preparation of composite nano-silica: Mix 35 mL of tetraethyl orthosilicate with 450 mL of anhydrous ethanol and stir until homogeneous to obtain solution A; mix 5 g of zinc oxide, 1.7 g of Tween-80, 80 mL of water, and 400 mL of anhydrous ethanol and stir until homogeneous. Sonicate at 30 kHz for 40 min, add 1.7 g of polyvinylpyrrolidone, stir until homogeneous, sonicate at 30 kHz for 40 min, add 23 mL of ammonia water, and stir until homogeneous to obtain solution B; stir all of the above solution B at room temperature, and simultaneously add all of the above solution A dropwise, controlling the dropwise addition time to 2.5 h. After the dropwise addition is completed, continue stirring for 2 h, centrifuge at 16000 rpm for 20 min, collect the precipitate, wash 4 times with anhydrous ethanol, wash 4 times with water, dry, then mix with 500 mL of zinc sulfate aqueous solution, stir for 2 h, centrifuge at 16000 rpm for 20 min, collect the precipitate, wash 4 times with water, and dry to obtain composite nano-silica; The average particle size of the zinc oxide is 30 nm; The mass concentration of the ammonia solution is 25%. The zinc sulfate aqueous solution has a mass concentration of 5%; 3. Preparation of in-machine functional coating liquid: Mix high temperature resistant resin emulsion, composite nano silica and functional additives at an oven-dry mass ratio of 23:80:5.2, stir evenly to obtain a mixture, mix the mixture with water at a mass ratio of 1:4.2, stir evenly to obtain the in-machine functional coating liquid; The functional additive is a mixture of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer, wherein the mass ratio of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer is 5.4:4.3:1; 4. Coating: After semi-wet calendering of the base paper, coating is performed using an in-machine coating liquid through a film transfer sizing machine, controlling the coating amount to 6g / m².2 After coating, the paper is dried to obtain a highly breathable and high-temperature resistant digital printing decorative base paper. The basis weight of the base paper is 85 g / m². 2 .

[0019] This embodiment also provides a digital printing decorative base paper prepared by the aforementioned preparation method.

[0020] Comparative Example 1 A method for preparing digital printing decorative base paper is as follows: Semi-wet calendering of the base paper yields digital printing decorative base paper; The basis weight of the base paper is 85 g / m². 2 .

[0021] This comparative example also provides a digital printing decorative base paper prepared by the aforementioned preparation method.

[0022] Comparative Example 2 Based on the preparation method of digital printing decorative base paper in Example 1, the preparation of the high-temperature resistant resin emulsion in step 1 is modified as follows: Aqueous resin is mixed with water and stirred evenly to obtain a high-temperature resistant resin emulsion with a solid content of 14%. The aqueous resin is an acrylic resin emulsion; The acrylic resin emulsion is an aqueous acrylic-styrene copolymer resin emulsion with a solid content of 42% and a number-average molecular weight of 5000.

[0023] This comparative example also provides a digital printing decorative base paper prepared by the aforementioned preparation method.

[0024] Comparative Example 3 Based on the preparation method of digital printing decorative base paper in Example 1, the second step of preparing composite nano-silica is modified as follows: 30 mL of tetraethyl orthosilicate was mixed with 400 mL of anhydrous ethanol and stirred until homogeneous to obtain solution A. 70 mL of water, 370 mL of anhydrous ethanol, and 20 mL of ammonia were mixed and stirred until homogeneous to obtain solution B. All of the above solutions B were stirred at room temperature, while all of the above solutions A were added dropwise over a period of 2 hours. After the addition was completed, stirring was continued for 1.5 hours. The mixture was then centrifuged at 14,000 rpm for 15 minutes. The precipitate was collected, washed three times with anhydrous ethanol, washed three times with water, and dried to obtain composite nano-silica. The mass concentration of the ammonia water is 25%.

[0025] This comparative example also provides a digital printing decorative base paper prepared by the aforementioned preparation method.

[0026] Performance Test 1 The digitally printed decorative base paper of Examples 1-4 and Comparative Examples 1-3 was printed using a digital inkjet printer. The air permeability, color density, and color density retention rate of the printed paper were then tested. The test results are as follows:

[0027] When testing the color density retention rate, the method is as follows: after printing on digitally printed decorative paper, the color density of the printed paper sample is measured as the color density before immersion in water. Then, the printed paper sample is placed in water and soaked at room temperature for 1 hour. After draining the excess water, it is placed in an oven and dried at 120℃ for 10 minutes. The color density is then measured again as the color density after immersion in water. The color density retention rate is calculated using the following formula: Color density retention rate = (Color density after immersion / Color density before immersion) × 100%.

[0028] As can be seen from the table above, Examples 1-4 showed better overall performance in terms of air permeability, color density, and color density retention compared to Comparative Examples 1-3. The main reason is that modifying the resin with casein reduced the resin's impact on the sealing of the base paper surface, while simultaneously improving ink absorption and fixation. The composite nano-silica, a complex of zinc oxide and silica, with silica coated on the zinc oxide surface in a porous form, further enhances air permeability, improves paper printing quality, and enhances ink fixation.

[0029] Performance Test 2 After weighing the digital printing decorative base paper from Examples 1-4 and Comparative Examples 1-3, the weight before impregnation was recorded. Then, the paper was manually impregnated with glue for 10 seconds, dried, and weighed again to obtain the weight after impregnation. The weight after impregnation was then divided by the weight before impregnation to obtain the amount of glue impregnated in 10 seconds. The impregnated digital printing decorative base paper was then placed on a fiberboard and pressed for 35 seconds at a hot-pressing temperature of 180°C and a hot-pressing pressure of 1.2 MPa. The surface bonding effect of the pressed board was observed, and the specific results are as follows:

[0030] As can be seen from the table above, Examples 1-4 showed better overall performance in terms of impregnation amount and pressing effect compared to Comparative Examples 1-3. The main reason is that modifying the resin with casein improves its dispersion stability and film-forming efficiency, as well as the high-temperature resistance of the digital printing decorative base paper. Adding zinc oxide and zinc sulfate to silica also improves its dispersibility and, consequently, the high-temperature resistance of the digital printing decorative base paper.

[0031] Performance Test 3 The dynamic and static friction coefficients of the digital printing decorative base paper surfaces of Examples 1-4 and Comparative Examples 1-3 were tested, and the test results are as follows:

[0032] As can be seen from the table above, Examples 1-4 showed better flatness results than Comparative Examples 1-3.

Claims

1. A method for preparing a highly breathable and high-temperature resistant digital printing decorative base paper, characterized in that, include: Prepare high-temperature resistant resin emulsion, prepare composite nano-silica, prepare internal coating functional coating liquid, and apply coating; The preparation of the high-temperature resistant resin emulsion involves mixing an aqueous resin with silica sol, stirring until homogeneous, obtaining a mixed solution, and then mixing the mixed solution with casein and water, stirring until homogeneous to obtain the high-temperature resistant resin emulsion. To prepare the composite nano-silica, tetraethyl orthosilicate and anhydrous ethanol are mixed and stirred until homogeneous to obtain solution A. Zinc oxide, Tween-80, water, and anhydrous ethanol are mixed and stirred until homogeneous, then sonicated. Polyvinylpyrrolidone is added and stirred until homogeneous, then sonicated again. Ammonia is added and stirred until homogeneous to obtain solution B. Solution B is stirred at room temperature while solution A is added dropwise. After the addition is complete, stirring is continued, followed by centrifugation, washing, and drying. Then, solution B is mixed with zinc sulfate aqueous solution, stirred, centrifuged, and the precipitate is collected, washed, and dried to obtain the composite nano-silica.

2. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 1, characterized in that, In the preparation of the high-temperature resistant resin emulsion, the mass ratio of aqueous resin to silica sol is 1:3-3.

3. The ratio of the mixed solution to casein by its oven-dry mass is 1-1.2:

1.

3. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 1, characterized in that, In the preparation of the high-temperature resistant resin emulsion, the aqueous resin is one of acrylic resin emulsion, polyurethane resin emulsion, and polyvinyl alcohol resin particles; The acrylic resin emulsion is an aqueous acrylic styrene copolymer resin emulsion with a solid content of 41-43% and a number average molecular weight of 4000-6000. The polyurethane resin emulsion is an aqueous polyurethane resin emulsion with a solid content of 29-31% and a number average molecular weight of 5000-8000. The polyvinyl alcohol resin particles are polyvinyl alcohol 1788 resin particles.

4. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 1, characterized in that, In the preparation of the high-temperature resistant resin emulsion, the solid content of the high-temperature resistant resin emulsion is 14-16%.

5. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 1, characterized in that, In the preparation of the composite nano silica, the volume ratio of tetraethyl orthosilicate to anhydrous ethanol in solution A is 30-35:400-450. In solution B, the ratio of zinc oxide, Tween-80, water, anhydrous ethanol, polyvinylpyrrolidone, and ammonia is 4.7-5g:1.5-1.7g:70-80mL:370-400mL:1.5-1.7g:20-23mL. The ratio of tetraethyl orthosilicate in solution A, zinc oxide in solution B, and zinc sulfate aqueous solution is 30-35 mL: 4.7-5 g: 400-500 mL.

6. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 1, characterized in that, In the preparation of the composite nano-silica, the average particle size of the zinc oxide is 30 nm; The mass concentration of the ammonia solution is 25%. The zinc sulfate aqueous solution has a mass concentration of 5%; The addition time of solution A is 2-2.5 hours.

7. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 1, characterized in that, The preparation of the in-machine functional coating liquid involves mixing high-temperature resistant resin emulsion, composite nano silica, and functional additives, stirring until homogeneous, and then mixing the mixture with water and stirring until homogeneous to obtain the in-machine functional coating liquid.

8. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 7, characterized in that, In the functional coating liquid prepared by the machine, the oven-dry mass ratio of high-temperature resistant resin emulsion, composite nano silica, and functional additives is 20-23:75-80:5-5.

2. The mass ratio of the mixture to water is 1:4-4.2; The functional additive is a mixture of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer, wherein the mass ratio of quaternary ammonium salt type fixing agent, polyether penetrant, and fatty alcohol defoamer is 5-5.4:4-4.3:

1.

9. The method for preparing the high-permeability, high-temperature resistant digital printing decorative base paper according to claim 1, characterized in that, The coating process involves semi-wet calendering the base paper, followed by coating with an in-machine coating liquid, and drying after coating to obtain a highly breathable and high-temperature resistant digital printing decorative base paper. In the coating process, the coating amount of the in-machine coating functional coating liquid is 3-8 g / m³. 2 ; The basis weight of the base paper is 80-100 g / m². 2 ; During coating, the coating is performed using a film transfer applicator.

10. A high-permeability, high-temperature resistant digital printing decorative base paper prepared by the preparation method according to any one of claims 1-9.

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