Preparation method of low-VoC environment-friendly adhesive special for wallpaper and wall cloth

Abstract

The invention relates to the technical field of high polymer materials, and particularly discloses a preparation method of a low-VoC environment-friendly adhesive special for wallpaper and wall cloth. Comprising the following steps: S1, adding polyvinyl alcohol into deionized water to obtain a mixed solution; s2, hydroxypropyl distarch phosphate, wood fibers and deionized water are mixed, and mixed slurry is obtained; s3, mixing the mixed solution with the mixed slurry to obtain a prepolymer; s4, cooling the prepolymer, and sequentially adding auxiliaries to obtain a mixture; s5, adding a rosin ethanol solution and a defoaming agent into the mixture to obtain a crude product; and S6, carrying out vacuum defoaming treatment on the crude product, then sterilizing, cooling and discharging to obtain the adhesive. The adhesive disclosed by the invention can be used for adhering various pure paper, non-woven fabrics, diatom ooze and heavy wallpaper and wall cloth, and has the advantages of extremely low VOC content, environment friendliness, no peculiar smell, high initial adhesion and strong lasting viscosity.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and more specifically, it relates to a method for preparing a low-VoC environmentally friendly adhesive for wallpaper and wall coverings. Background Technology

[0002] Adhesives are used in the field of polymer materials to achieve the connection and functional integration of different substrates. They are widely used for bonding between polymer materials and between polymer materials and heterogeneous materials such as metals, glass, and wood. Specific applications include lightweight automotive manufacturing, electronic information packaging, construction engineering, packaging material composites, medical consumables, and new energy equipment. They are also compatible with various application processes such as hot melt, solvent-based, water-based, and UV curing to meet the bonding needs of different polymer materials. Their advantages lie in their excellent bonding performance, forming a high-strength, fatigue-resistant bonding interface through intermolecular forces, with uniform stress distribution, avoiding damage to polymer materials from mechanical bonding. They also have broad compatibility, allowing for customized formulations for polymer materials of different polarities and hardness, solving the challenges of bonding heterogeneous materials.

[0003] Related adhesives use high molecular polymers or simply modified natural polymers as base materials and rely on high-temperature polymerization or strong solvent dispersion processes to obtain bonding performance. However, these methods often result in uneven internal structure due to violent reactions and simple formulations. While pursuing high bonding strength, they introduce a large amount of organic solvents or produce volatile byproducts such as formaldehyde, resulting in high volatile organic compound content and poor environmental friendliness in the final product. Summary of the Invention

[0004] To address the problem of high volatile organic compound (VOC) content and poor environmental friendliness in adhesives that use polymers or simply modified natural polymers as base materials, this application provides a method for preparing a low-VoC environmentally friendly wallpaper and wallcovering adhesive.

[0005] This application provides a method for preparing a low-VoC environmentally friendly wallpaper and wallcovering adhesive, using the following technical solution: A method for preparing a low-VOC environmentally friendly wallpaper and wallcovering adhesive includes the following steps: S1. Add polyvinyl alcohol to deionized water and allow it to swell at room temperature to obtain a mixed solution; S2. Hydroxypropyl distarch phosphate, wood fiber and deionized water are mixed and stirred to disperse to obtain a mixed slurry; S3. Under inert gas protection, the mixed solution and the mixed slurry are mixed, heated to 75-85℃, a silane coupling agent is added, and the reaction is maintained at the temperature for 20-40 minutes to obtain the prepolymer. S4. Cool the prepolymer to 45-55℃, add sodium chloride, chitosan, nano titanium dioxide, hydroxy amino acids and composite antifungal agent in sequence, stir at constant temperature for 30-60 min to obtain a mixture; S5. Add rosin ethanol solution and defoamer to the mixture, and continue stirring until the system is homogeneous to obtain crude product; S6. The crude product is subjected to vacuum degassing treatment, followed by surface sterilization using pulsed intense light technology, and discharged after cooling to room temperature to obtain the adhesive.

[0006] By adopting the above technical solution, using polyvinyl alcohol and hydroxypropyl distarch phosphate as the main film-forming substances, a composite colloidal structure is constructed through stepwise feeding and controlled reaction. The introduction of wood fiber enhances the cohesion of the system and the anti-sagging properties during construction. The subsequent gradient addition of functional additives and mild treatment conditions ensure the activation of each component while minimizing the generation of volatile organic compounds caused by high temperature. Therefore, the final adhesive not only has a balanced initial tack and holding power, but also achieves a balance between low volatile organic compound content and environmental friendliness.

[0007] Preferably, in step S1, the amount of polyvinyl alcohol used accounts for 2% to 10% of the total mass of the adhesive; the swelling time is not less than 12 hours.

[0008] By adopting the above technical solution, the amount of polyvinyl alcohol is controlled within a certain range, thereby ensuring that it forms a continuous and appropriately strong colloidal network skeleton in the system. Too little amount will result in insufficient colloidal strength, while too much will easily lead to an overly viscous system that affects construction. Setting a certain swelling time allows the polyvinyl alcohol molecular chains to expand in water, preventing insufficiently swollen particles from forming impurities that are difficult to eliminate in subsequent heating steps. Therefore, this combination of parameters lays the foundation for uniform mixing and stable reaction with starch and other components in subsequent steps, ensuring the overall uniformity and stability of the adhesive solution.

[0009] Preferably, in step S3, the silane coupling agent is vinyltriethoxysilane; the reaction is carried out at 80-85°C for 25-35 minutes; and the inert gas is nitrogen.

[0010] By adopting the above technical solution, since vinyltriethoxysilane is selected as the coupling agent, its ethoxy group can condense with the hydroxyl groups on the starch molecular chain and the hydroxyl groups of polyvinyl alcohol after hydrolysis, while its vinyl group introduces potential cross-linking points into the system, improving water resistance. Under nitrogen protection, the reaction is carried out at 80-85℃ for 25-35 minutes. This temperature range can promote the hydrolysis and condensation reaction of the silane coupling agent, while avoiding excessive starch gelatinization or polyvinyl alcohol degradation caused by excessive temperature. The inert atmosphere prevents the material from oxidizing and discoloring. Therefore, this step achieves effective bridging between organic polymers, inorganic fillers and fibers, enhancing the cohesive strength of the adhesive and its wetting and adhesion to the wallpaper substrate.

[0011] Preferably, in step S4, the mass ratio of chitosan, nano-titanium dioxide, and hydroxy amino acids is 1:1.5 to 2:1; the hydroxy amino acids are a mixture of L-serine and L-tyrosine in a mass ratio of 1:1.

[0012] By adopting the above technical solution, the amino groups on the chitosan molecular chain and the specific functional groups of nano-titanium dioxide and hydroxy amino acids can interact through coordination bonds, hydrogen bonds, etc., to construct a dynamic cross-linked network in the colloidal system. The nano-titanium dioxide with a mass ratio of 1.5 to 2:1 provides sufficient surface area and active sites, while the mixed hydroxy amino acids of serine and tyrosine participate in the network construction and promote the formaldehyde capture reaction due to the differences in their side chain groups. Therefore, this combination of components not only enhances the colloidal performance as a functional filler, but also synergistically exerts the environmental purification effect of adsorbing and catalytically degrading formaldehyde.

[0013] Preferably, in step S4, the composite antifungal agent is composed of zinc oxide and isothiazolinone in a mass ratio of 1 to 3.5:1; before being added, the composite antifungal agent is premixed with a portion of nano-titanium dioxide at a rotation speed of 300 to 500 r / min for 15 to 30 min.

[0014] By adopting the above technical solution, zinc oxide, as an inorganic antifungal agent, has long-lasting effect and safety, while isothiazolinone, as an organic antifungal agent, has rapid onset of action. The combination of the two can achieve synergistic effect, broaden the antibacterial spectrum and extend the shelf life. Before addition, the antifungal agent is pre-mixed with some nano-titanium dioxide at a medium-low speed, which allows the antifungal agent component to be more uniformly loaded on the huge specific surface area of ​​nano-titanium dioxide. Therefore, this pretreatment process improves the dispersion and utilization efficiency of the antifungal agent in the colloid, thereby enhancing the antifungal durability and uniformity of the adhesive film after formation.

[0015] Preferably, in step S5, the rosin ethanol solution contains 20% to 30% rosin by mass; the defoamer is tributyl phosphate or silicone oil defoamer, and its addition amount is 0.1% to 0.5% of the total mass of the adhesive.

[0016] By adopting the above technical solution, a certain mass fraction of rosin-ethanol solution is used, in which rosin, as a natural tackifying resin, can improve the initial adhesion of the adhesive, and ethanol, as a solvent, helps it to disperse quickly and be compatible with the system; by selecting tributyl phosphate or silicone oil defoamers and adding them in trace amounts, bubbles generated during production and construction can be destroyed and foam regeneration can be inhibited without negatively affecting the properties of the colloid. Therefore, this step ensures that the adhesive has smoothness during construction and good bonding appearance.

[0017] Preferably, in step S6, the vacuum degree of the vacuum degassing treatment is -0.08 to -0.10 MPa, and the treatment time is 10 to 30 minutes; the light energy of the pulsed intense light technology is 0.5 to 2.0 J / cm². 2 The number of pulses is 1 to 3.

[0018] By adopting the above technical solution, degassing under a high vacuum can remove the fine bubbles entangled in the previous process and generated by the reaction, ensuring that the adhesive film is dense and defect-free. Subsequently, pulsed intense light is used for surface sterilization. This non-thermal sterilization technology kills microorganisms at room temperature, avoiding changes in colloidal properties or the generation of volatile organic compounds caused by thermal sterilization. Therefore, while ensuring the safety of the product's microbiological indicators, the low volatile organic compound characteristics and storage stability of the adhesive are maintained.

[0019] Preferably, before step S2, a step of preparing the modified filler is included: styrene, divinylbenzene, butyl acrylate and hydroxyethyl methacrylate are added to deionized water, heated to 75-80°C under nitrogen protection and stirred, then cooled to 40-45°C, the pH is adjusted to 4.5-5.5, flavanol and potassium persulfate aqueous solution are added, and after reacting for 4-5 hours, the mixture is cooled, filtered, dried and ground to obtain a modified filler with a particle size of 400-500 nm.

[0020] By adopting the above technical solution, styrene provides rigidity, butyl acrylate provides flexibility, divinylbenzene serves as a crosslinking agent, and hydroxyethyl methacrylate introduces active hydroxyl groups. Under the action of an initiator, polymer microspheres with core-shell or interpenetrating network structures are copolymerized to obtain the filler. The introduction of flavanols further endows the filler with antioxidant and synergistic adhesive properties. Controlling the particle size within a certain range is beneficial for its uniform dispersion in the colloid without thickening. Therefore, this self-made modified filler, as a functional reinforcing component, can improve the mechanical properties, aging resistance, and penetration and anchoring effect of the adhesive with porous wallpaper and wallcovering substrates.

[0021] Preferably, the modified filler is added together with nano-titanium dioxide in step S4, and its amount is 1% to 5% of the total mass of the adhesive.

[0022] By adopting the above technical solution, the modified filler and nano titanium dioxide are added simultaneously in S4, which promotes their synergy in the colloidal system. Nano titanium dioxide focuses on photocatalysis and surface function, while the modified polymer filler focuses on mechanical reinforcement and internal structure regulation. The dosage is controlled between 1% and 5%, which can not only exert the effect of reinforcement and toughening, but also avoid the decrease in adhesive fluidity or unnecessary increase in cost caused by excessive addition. Therefore, the setting of the timing and dosage of addition makes the advantages of the two fillers complement each other and synergistically improve the overall performance of the adhesive.

[0023] Preferably, in step S4, a natural plant anti-mold extract is also added. The natural plant anti-mold extract is obtained by decocting Eucommia ulmoides leaves, cloves, Litsea cubeba, cinnamon, garlic, rosemary, orange peel and forsythia with water. It is added after the compound anti-mold agent is added, and the amount added is 5% to 15% of the total mass of the adhesive.

[0024] By adopting the above technical solution, the selected plant extracts contain a variety of natural compounds with broad-spectrum antibacterial activity, forming a multi-layered anti-mold barrier that complements the compound anti-mold agent with organic and inorganic components. Adding them after the compound anti-mold agent allows the natural active ingredients to be better retained in the colloidal system, ensuring a certain amount of addition to guarantee an effective antibacterial concentration. Simultaneously, its natural properties further reduce the product's environmental impact. Therefore, the introduction of this natural plant anti-mold extract not only enhances the anti-mold and antibacterial effect of the adhesive but also improves the overall environmental friendliness and safety of the formulation.

[0025] In summary, this application has the following beneficial effects: 1. Because this application adopts a stepwise feeding and controlled reaction preparation method, it constructs a composite colloidal structure with polyvinyl alcohol and hydroxypropyl distarch phosphate as the main film-forming substances, and strengthens the cohesion of the system by wood fiber. Combined with the gradient addition of functional additives and mild condition treatment, the synergy between each step avoids the generation of volatile organic compounds caused by high temperature. Therefore, it achieves the effect of giving the adhesive low volatile organic compound content, environmental friendliness, and a balanced and unified initial tack and holding power.

[0026] 2. In this application, silane coupling agents are preferably reacted under inert gas protection at a specific temperature. This condition promotes the hydrolysis and condensation of silane coupling agents, while bridging components such as polyvinyl alcohol, starch, and fiber. It also prevents the materials from over-gelatinizing or degrading at a suitable temperature, thus achieving the effect of improved cohesive strength of the adhesive and enhanced wetting and adhesion to the wallpaper substrate.

[0027] 3. The method of this application, by introducing the synergistic addition of modified filler and nano titanium dioxide, and the multiple anti-mold combination of composite anti-mold agent and natural plant anti-mold extract, the above components construct a dynamic cross-linking network and a uniformly dispersed antibacterial barrier in the colloidal system, and achieve complementary performance by relying on premixing and gradient addition, thereby improving the mechanical properties, aging resistance, anti-mold durability and overall environmental safety of the adhesive. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive proposed in this application. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Example 1: This example provides a method for preparing a low-VoC environmentally friendly wallpaper and wallcovering adhesive, comprising the following steps: S1. Add polyvinyl alcohol to deionized water and allow it to swell at room temperature to obtain a mixed solution; Polyvinyl alcohol accounts for 2% of the total mass of the adhesive; the swelling time is 12 hours.

[0031] Preparation of modified filler: Styrene, divinylbenzene, butyl acrylate and hydroxyethyl methacrylate were added to deionized water, heated to 75°C and stirred under nitrogen protection, then cooled to 40°C, pH adjusted to 4.5, flavanol and potassium persulfate aqueous solution were added, and after reacting for 4 hours, the mixture was cooled, filtered, dried and ground to obtain a modified filler with a particle size of 400 nm.

[0032] S2. Hydroxypropyl distarch phosphate, wood fiber and deionized water are mixed and stirred to disperse to obtain a mixed slurry; S3. Under inert gas protection, the mixed solution and the mixed slurry are mixed, heated to 80.0℃, a silane coupling agent is added, and the reaction is maintained at this temperature for 25 minutes to obtain the prepolymer. The silane coupling agent is vinyltriethoxysilane; the reaction is carried out at 80.0℃ for 25 minutes; the inert gas is nitrogen.

[0033] S4. Cool the prepolymer to 45°C, then add sodium chloride, chitosan, nano titanium dioxide, modified filler, hydroxy amino acids, composite antifungal agent, and natural plant antifungal extract in sequence. Stir at a constant temperature for 30 minutes to obtain a mixture. The mass ratio of chitosan, nano-titanium dioxide, and hydroxy amino acids is 1:1.5:1; the hydroxy amino acids are a mixture of L-serine and L-tyrosine in a mass ratio of 1:1; the composite antifungal agent is a compound of zinc oxide and isothiazolinone in a mass ratio of 1:1; before addition, the composite antifungal agent is premixed with a portion of nano-titanium dioxide at a speed of 300 r / min for 15 minutes; the modified filler is added together with nano-titanium dioxide in step S4, and its dosage is 1% of the total mass of the adhesive; the natural plant antifungal extract is obtained by decocting Eucommia ulmoides leaves, cloves, Litsea cubeba, cinnamon, garlic, rosemary, orange peel, and Forsythia suspensa with water; it is added after the composite antifungal agent is added, and the amount added is 5% of the total mass of the adhesive.

[0034] S5. Add rosin ethanol solution and defoamer to the mixture, and continue stirring until the system is homogeneous to obtain crude product; The rosin ethanol solution contains 20% rosin by mass; the defoamer is tributyl phosphate or silicone oil defoamer, and its addition amount is 0.1% of the total mass of the adhesive.

[0035] S6. The crude product is subjected to vacuum degassing treatment, followed by surface sterilization using pulsed intense light technology. After cooling to room temperature, the product is discharged to obtain the adhesive. The vacuum degassing process involved a vacuum level of -0.08 MPa and a processing time of 10 minutes; the pulsed high-intensity light (PIL) irradiation energy was 0.5 J / cm². 2 The number of pulses is 1.

[0036] Example 2: This example provides a method for preparing a low-VoC environmentally friendly wallpaper and wallcovering adhesive, comprising the following steps: S1. Add polyvinyl alcohol to deionized water and allow it to swell at room temperature to obtain a mixed solution; Polyvinyl alcohol accounts for 6% of the total mass of the adhesive; the swelling time is 12 hours.

[0037] Preparation of modified filler: Styrene, divinylbenzene, butyl acrylate and hydroxyethyl methacrylate were added to deionized water and heated to 77.5℃ under nitrogen protection and stirred. Then the mixture was cooled to 42.5℃ and the pH was adjusted to 5.0. Flavanol and potassium persulfate aqueous solution were added. After reacting for 4.5 hours, the mixture was cooled, filtered, dried and ground to obtain a modified filler with a particle size of 450nm.

[0038] S2. Hydroxypropyl distarch phosphate, wood fiber and deionized water are mixed and stirred to disperse to obtain a mixed slurry; S3. Under inert gas protection, the mixed solution and the mixed slurry are mixed, heated to 82.5℃, a silane coupling agent is added, and the reaction is maintained at this temperature for 30 minutes to obtain the prepolymer. The silane coupling agent is vinyltriethoxysilane; the reaction is carried out at 82.5℃ for 30 minutes; the inert gas is nitrogen.

[0039] S4. Cool the prepolymer to 50°C, then add sodium chloride, chitosan, nano titanium dioxide, modified filler, hydroxy amino acids, composite antifungal agent, and natural plant antifungal extract in sequence. Stir at a constant temperature for 45 minutes to obtain a mixture. The mass ratio of chitosan, nano-titanium dioxide, and hydroxy amino acids is 1:1.75:1; the hydroxy amino acids are a mixture of L-serine and L-tyrosine in a mass ratio of 1:1; the composite antifungal agent is a compound of zinc oxide and isothiazolinone in a mass ratio of 2.25:1; before addition, the composite antifungal agent is premixed with a portion of nano-titanium dioxide at a speed of 400 r / min for 22.5 minutes; the modified filler is added together with nano-titanium dioxide in step S4, and its amount is 3% of the total mass of the adhesive; the natural plant antifungal extract is obtained by decocting Eucommia ulmoides leaves, cloves, Litsea cubeba, cinnamon, garlic, rosemary, orange peel, and Forsythia suspensa with water; it is added after the composite antifungal agent is added, and the amount added is 10% of the total mass of the adhesive.

[0040] S5. Add rosin ethanol solution and defoamer to the mixture, and continue stirring until the system is homogeneous to obtain crude product; The rosin ethanol solution contains 25% rosin by mass; the defoamer is tributyl phosphate or silicone oil defoamer, and its addition amount is 0.3% of the total mass of the adhesive.

[0041] S6. The crude product is subjected to vacuum degassing treatment, followed by surface sterilization using pulsed intense light technology. After cooling to room temperature, the product is discharged to obtain the adhesive. The vacuum degassing process involved a vacuum level of -0.09 MPa and a processing time of 20 minutes; the pulsed high-intensity light (PIL) irradiation energy was 1.25 J / cm². 2 The number of pulses is 2.

[0042] Example 3: This example provides a method for preparing a low-VoC environmentally friendly wallpaper and wallcovering adhesive, comprising the following steps: S1. Add polyvinyl alcohol to deionized water and allow it to swell at room temperature to obtain a mixed solution; Polyvinyl alcohol accounts for 10% of the total mass of the adhesive; the swelling time is 12 hours.

[0043] Preparation of modified filler: Styrene, divinylbenzene, butyl acrylate and hydroxyethyl methacrylate were added to deionized water, heated to 80°C and stirred under nitrogen protection, then cooled to 45°C, pH adjusted to 5.5, flavanol and potassium persulfate aqueous solution were added, and after reacting for 5 hours, the mixture was cooled, filtered, dried and ground to obtain a modified filler with a particle size of 500 nm.

[0044] S2. Hydroxypropyl distarch phosphate, wood fiber and deionized water are mixed and stirred to disperse to obtain a mixed slurry; S3. Under inert gas protection, the mixed solution and the mixed slurry are mixed, heated to 85°C, a silane coupling agent is added, and the reaction is maintained at the temperature for 35 minutes to obtain the prepolymer. The silane coupling agent is vinyltriethoxysilane; the reaction is carried out at 85°C for 35 minutes; the inert gas is nitrogen.

[0045] S4. Cool the prepolymer to 55°C, then add sodium chloride, chitosan, nano titanium dioxide, modified filler, hydroxy amino acids, composite antifungal agent, and natural plant antifungal extract in sequence. Stir at a constant temperature for 60 minutes to obtain a mixture. The composition of the adhesive consists of a mixture of chitosan, nano-titanium dioxide, and hydroxy amino acids in a mass ratio of 1:2:1; the hydroxy amino acids are a mixture of L-serine and L-tyrosine in a mass ratio of 1:1; the composite antifungal agent is a compound of zinc oxide and isothiazolinone in a mass ratio of 3.5:1; before addition, the composite antifungal agent is premixed with a portion of nano-titanium dioxide at a speed of 500 r / min for 30 minutes; the modified filler is added together with the nano-titanium dioxide in step S4, and its dosage is 5% of the total mass of the adhesive; the natural plant antifungal extract is obtained by decocting Eucommia ulmoides leaves, cloves, Litsea cubeba, cinnamon, garlic, rosemary, orange peel, and Forsythia suspensa with water; it is added after the composite antifungal agent, and the amount added is 15% of the total mass of the adhesive.

[0046] S5. Add rosin ethanol solution and defoamer to the mixture, and continue stirring until the system is homogeneous to obtain crude product; The rosin ethanol solution contains 30% rosin by mass; the defoamer is tributyl phosphate or silicone oil defoamer, and its addition amount is 0.5% of the total mass of the adhesive.

[0047] S6. The crude product is subjected to vacuum degassing treatment, followed by surface sterilization using pulsed intense light technology. After cooling to room temperature, the product is discharged to obtain the adhesive. The vacuum degassing process involved a vacuum level of -0.10 MPa and a processing time of 30 minutes; the pulsed high-intensity light (PIL) irradiation energy was 2.0 J / cm². 2 The number of pulses is 3.

[0048] Comparative Example 1: This comparative example refers to the content of Example 1, except that the amount of polyvinyl alcohol used in step S1 accounts for 1% of the total mass of the adhesive, and the rest is the same as in Example 1.

[0049] Comparative Example 2: This comparative example is based on the content of Example 1, except that the temperature is raised to 56°C in step S3 for the reaction, and the rest is the same as Example 1.

[0050] Comparative Example 3: This comparative example refers to the content of Example 1, except that the heat preservation reaction time in step S3 is 15 minutes, and the rest of the content is the same as Example 1.

[0051] Comparative Example 4: This comparative example refers to the content of Example 1, except that the prepolymer is cooled to 30°C in step S4, and the rest is the same as in Example 1.

[0052] Comparative Example 5: This comparative example refers to the content of Example 1, except that in step S4, the composite antifungal agent is composed of zinc oxide and isothiazolinone in a mass ratio of 0.5:1. The rest of the content is the same as in Example 1.

[0053] Comparative Example 6: This comparative example refers to Example 1, except that the light energy of the pulsed high-intensity light technology in step S6 is 0.3 J / cm². 2 The rest of the content is the same as in Example 1.

[0054] Performance testing Sample preparation: Adhesive samples were prepared according to the preparation methods described in Examples 1-3 and Comparative Examples 1-6. After preparation, all samples were allowed to stand and mature for 24 hours under standard environmental conditions, and then various performance indicators were tested.

[0055] Volatile organic compound (VOC) content detection: The adhesive samples prepared in each example and comparative example were uniformly coated onto a specified simulated substrate, with precise control over the coating amount. The coated specimens were then placed in an environmental test chamber conforming to the standard specifications and sealed for a certain period under set temperature, humidity, and air exchange rate conditions. Gas chromatography-mass spectrometry (GC-MS) was used to collect and analyze the VOCs in the air within the test chamber. The total VOCs released per unit area or unit mass of adhesive and the content of each individual hazardous substance were quantitatively determined using the standard curve method to verify its environmental friendliness. The testing standard for this item refers to the method for determining the VOC content in the "Limits of Hazardous Substances in Adhesives for Interior Decoration and Renovation Materials".

[0056] Initial tack and holding power testing: Initial tack is tested using the rolling ball plane stopping method. A steel ball of a specific size is rolled down the surface of the sample coated with adhesive from the top of an inclined plate. The largest steel ball that can stop completely on the adhesive surface is recorded, thus characterizing its initial tack. Holding power testing uses a standard holding power tester. A certain area of ​​adhesive sample is bonded to a standard steel plate, and a specified weight is suspended below. The sample is suspended vertically under specific conditions, and the time required for the sample to completely detach is recorded, thus evaluating its creep resistance and long-lasting adhesion performance. The testing standards for this test refer to the test methods for initial tack and holding power in the series of standards for pressure-sensitive adhesive tapes and adhesive products.

[0057] Anti-mold performance testing: Each adhesive sample was prepared into a uniform thin coating. The coating sample was placed in a petri dish containing high-nutrient agar medium, and the surface of the sample was uniformly inoculated with a mixed mold spore suspension. The petri dish was then placed in a constant temperature and humidity mold incubator and cultured for a specified number of days under suitable mold growth conditions. After cultivation, the sample was removed, and the mold growth on the sample surface was observed visually and under a microscope to assess the mold coverage area level. The testing standards for this item refer to the "Test Method for Anti-mold Effect of Anti-mold Agents" and related standards for determining the anti-mold properties of paint films.

[0058] Heat aging resistance test: The prepared adhesive test specimens or pure adhesive film specimens are placed in a temperature-controlled constant temperature aging test chamber and continuously placed at a specific constant temperature above room temperature for a specified period of time. After the aging treatment, the specimens are removed and conditioned to equilibrium in a standard environment. Then, the performance retention rate after aging is tested according to the aforementioned test methods for holding power or tensile shear strength, thereby evaluating the aging resistance of the adhesive system. The test standards for this test are based on the relevant conditions in "Test Methods for Aging of Adhesives" and "Test Methods for Thermal Aging of Plastics".

[0059] Table 1: Comparison of Detection Data between Examples and Comparative Examples ; Example Conclusion: As can be seen from Examples 1-3 and Comparative Example 1, and Table 1, the appropriate use of polyvinyl alcohol helps to construct a stable colloidal network structure, enhances the matrix strength and cohesion of the adhesive, thereby improving the bonding performance, reducing the release of volatile organic compounds, and improving the overall durability.

[0060] As can be seen from Examples 1-3 and Comparative Example 2, and Table 1, a suitable reaction temperature can effectively activate the crosslinking reaction of the silane coupling agent, promote the formation of a denser molecular network in the prepolymer, thereby enhancing the initial adhesion, long-lasting bonding ability and heat aging resistance of the adhesive.

[0061] As can be seen from Examples 1-3 and Comparative Example 3, and Table 1, sufficient reaction time is beneficial for the complete formation and uniform cross-linking of the prepolymer, ensuring the effective bonding of the subsequent filler and the matrix, thereby improving the adhesive stability, anti-mildew effect and environmental performance of the adhesive.

[0062] As can be seen from Examples 1-3 and Comparative Example 4, and Table 1, an appropriate cooling temperature helps maintain the dispersibility and reactivity of active fillers such as chitosan and nano-titanium dioxide, improves their synergistic effect with the matrix, and thus enhances the adhesive's antifungal properties, thermal stability, and overall performance balance.

[0063] As can be seen from Examples 1-3 and Comparative Example 5, and Table 1, a reasonable ratio of composite antifungal agents can exert the synergistic antibacterial effect of zinc oxide and isothiazolinone, reducing damage to the colloidal structure while providing long-lasting antifungal protection, thereby improving the durability, safety and environmental friendliness of the adhesive.

[0064] As can be seen from Examples 1-3 and Comparative Example 6, and Table 1, appropriate pulsed light sterilization treatment can eliminate microbial contamination, ensure the purity and chemical stability of the adhesive system, and thus improve its long-term storage safety, aging resistance and reliability.

[0065] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a low-VoC environmentally friendly wallpaper and wallcovering adhesive, characterized in that, Includes the following steps: S1. Polyvinyl alcohol is added to deionized water and swelled at room temperature to obtain a mixed solution; S2. Hydroxypropyl distarch phosphate, wood fiber and deionized water are mixed and stirred to disperse to obtain a mixed slurry; S3. Under inert gas protection, the mixed solution and the mixed slurry are mixed, heated to 75-85°C, a silane coupling agent is added, and the reaction is maintained at the temperature for 20-40 minutes to obtain the prepolymer. S4. Cool the prepolymer to 45-55℃, add sodium chloride, chitosan, nano titanium dioxide, hydroxy amino acids and composite antifungal agent in sequence, stir at constant temperature for 30-60 minutes to obtain a mixture; S5. Add rosin ethanol solution and defoamer to the mixture, and continue stirring until the system is homogeneous to obtain crude product; S6. The crude product is subjected to vacuum degassing treatment, followed by surface sterilization using pulsed intense light technology, and discharged after cooling to room temperature to obtain the adhesive.

2. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, In step S1, the amount of polyvinyl alcohol used accounts for 2% to 10% of the total mass of the adhesive; the swelling time is not less than 12 hours.

3. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, In step S3, the silane coupling agent is vinyltriethoxysilane; the reaction is carried out at 80-85°C for 25-35 minutes; the inert gas is nitrogen.

4. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, In step S4, the mass ratio of chitosan, nano-titanium dioxide and hydroxy amino acids is 1:(1.5~2):1; the hydroxy amino acids are a mixture of L-serine and L-tyrosine in a mass ratio of 1:

1.

5. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, In step S4, the composite antifungal agent is composed of zinc oxide and isothiazolinone in a mass ratio of (1-3.5):1; before being added, the composite antifungal agent is premixed with a portion of nano-titanium dioxide. The premixing is carried out at a speed of 300-500 r / min for 15-30 minutes.

6. The method for preparing a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, In step S5, the rosin ethanol solution contains 20% to 30% rosin by mass; the defoamer is tributyl phosphate or silicone oil defoamer, and its addition amount is 0.1% to 0.5% of the total mass of the adhesive.

7. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, In step S6, the vacuum degree of the vacuum degassing treatment is -0.08 to -0.10 MPa, and the treatment time is 10 to 30 minutes; the light energy of the pulsed intense light technology is 0.5 to 2.0 J / cm². 2 The number of pulses is 1 to 3.

8. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, Before step S2, a step for preparing the modified filler is also included: styrene, divinylbenzene, butyl acrylate and hydroxyethyl methacrylate are added to deionized water, heated to 75-80°C under nitrogen protection and stirred and mixed, then cooled to 40-45°C, the pH is adjusted to 4.5-5.5, flavanol and potassium persulfate aqueous solution are added, and after reacting for 4-5 hours, the mixture is cooled, filtered, dried and ground to obtain a modified filler with a particle size of 400-500 nm.

9. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 8, characterized in that, The modified filler is added together with nano-titanium dioxide in step S4, and its amount is 1% to 5% of the total mass of the adhesive.

10. The preparation method of a low-VoC environmentally friendly wallpaper and wallcovering adhesive according to claim 1, characterized in that, In step S4, a natural plant anti-mold extract is also added. The natural plant anti-mold extract is obtained by decocting Eucommia ulmoides leaves, cloves, Litsea cubeba, cinnamon, garlic, rosemary, orange peel and forsythia with water. It is added after the compound anti-mold agent is added, and the amount added is 5% to 15% of the total mass of the adhesive.

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