Weather-resistant paper adhesive, preparation method and application thereof

Abstract

This invention provides weather-resistant self-adhesive for paper, its preparation method, and its application. The self-adhesive includes an adhesive layer comprising the following raw materials in parts by weight: 40-45 parts butyl acrylate, 30-35 parts methyl methacrylate, 0.5-0.7 parts polyvinyl alcohol, 4-5 parts methacrylamide, 4-6 parts acrylamide, 60-65 parts styrene-acrylate copolymer emulsion, 3-4 parts nano-silica, 16-18 parts nano-tin antimony oxide@PDA composite microspheres, 2.0-2.5 parts initiator, 0.8-1.2 parts ultraviolet absorber, 0.3-0.4 parts light stabilizer, and 180-190 parts deionized water. This weather-resistant self-adhesive for paper improves the weather resistance of the self-adhesive in long-term outdoor environments, mitigating the problems of adhesive layer brittleness and decreased adhesion caused by continuous ultraviolet radiation, as well as the stress concentration and microcracks within the adhesive layer caused by drastic temperature changes, which affect overall performance and service life.

Description

Technical Field

[0001] This invention relates to the field of self-adhesive technology, specifically to self-adhesive for weather-resistant paper, its preparation method, and its application. Background Technology

[0002] With the rapid development of the packaging and labeling industries, the performance requirements for self-adhesive materials are increasing. Weather-resistant paper self-adhesive, as an important functional material, has wide applications in outdoor advertising, product labeling, logistics labels, and many other fields. It not only needs to possess excellent adhesion properties, achieving firm bonding to various material surfaces, but also needs to maintain stable performance under various harsh environmental conditions, such as light exposure, temperature changes, and humidity fluctuations, without peeling, discoloration, or aging.

[0003] Patent CN118995059B discloses a self-adhesive label, its preparation method, and its application. The self-adhesive label has a structure comprising, from top to bottom, a top layer, an adhesive layer, and a bottom layer. The adhesive layer is prepared from an adhesive, which, by weight, comprises the following raw materials: 70-75 parts methacrylic acid, 0.6-0.8 parts polyvinyl alcohol, 9-11 parts highly polar monomer, 50-55 parts polyoctene copolymer emulsion, 4-5 parts nanocrystalline cellulose, 20-24 parts modified nano-titanium dioxide, 2.6-2.8 parts initiator aqueous solution, 0.8-1.2 parts ultraviolet absorber, 0.3-0.5 parts dispersant, and 200-210 parts deionized water. The self-adhesive label prepared by this application exhibits excellent anti-aging properties, thermal stability, and adhesive strength, while also being resistant to cracking, making it suitable for various applications.

[0004] Although existing self-adhesive labels incorporate weather-resistant components such as UV absorbers and modified nano-titanium dioxide, their weather resistance remains unsatisfactory under long-term extreme outdoor conditions, such as strong ultraviolet radiation at high altitudes and freeze-thaw cycles in cold regions. Continuous UV exposure causes the polymer molecular chains in the adhesive layer to break, leading to brittleness and decreased adhesion. Drastic temperature changes cause stress concentration within the adhesive layer, generating microcracks, which in turn affect the overall performance and service life of the self-adhesive. To address these issues, this invention proposes a weather-resistant self-adhesive for paper, its preparation method, and its applications. Summary of the Invention

[0005] The purpose of this invention is to provide weather-resistant self-adhesive paper, its preparation method and application, which improves the weather resistance of self-adhesive paper in long-term outdoor environments, and improves the problems of adhesive layer brittleness and decreased adhesion caused by continuous ultraviolet radiation, as well as the stress concentration and microcracks in the adhesive layer caused by drastic temperature changes, which affect the overall performance and service life.

[0006] On one hand, the present invention provides a weather-resistant self-adhesive for paper, comprising an adhesive layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 40-45 parts butyl acrylate, 30-35 parts methyl methacrylate, 0.5-0.7 parts polyvinyl alcohol, 4-5 parts methacrylamide, 4-6 parts acrylamide, 60-65 parts styrene-acrylate copolymer emulsion, 3-4 parts nano silica, 16-18 parts nano antimony tin oxide@PDA composite microspheres, 2.0-2.5 parts initiator, 0.8-1.2 parts ultraviolet absorber, 0.3-0.4 parts light stabilizer, and 180-190 parts deionized water.

[0007] Furthermore, the preparation method of the nano-tin antimony oxide@PDA composite microspheres includes: dissolving dopamine hydrochloride in Tris-HCl buffer solution with pH=8.0-9.0, reacting at 20-30℃ and 200-300rpm for 22-24h, collecting the product by centrifugation, dispersing it in deionized water to obtain a dispersion with a solid content of about 0.4%-0.6%; then adding SnCl4·5H2O, SbCl3 and urea in a water bath at 65-75℃, reacting at 65-75℃ for 6-8h, and centrifuging and washing after the reaction is completed to obtain the final product.

[0008] Furthermore, the ratio of dopamine hydrochloride to Tris-HCl buffer is 0.8-1.2 g: 450-550 mL.

[0009] Furthermore, the ratio of the dispersion, SnCl4·5H2O, SbCl3 and urea is 200-250mL: 0.4-0.6g: 0.04-0.06g: 1.8-2.2g.

[0010] Furthermore, the initiator is ammonium persulfate.

[0011] Furthermore, the ultraviolet absorber is BASF UV327.

[0012] Furthermore, the light stabilizer is the hindered amine light stabilizer Chimassorb 2020.

[0013] On the other hand, the present invention also provides a method for preparing weather-resistant paper self-adhesive, wherein the adhesive layer preparation steps include: mixing deionized water and polyvinyl alcohol in parts by mass, purging high-purity nitrogen gas to remove oxygen from the system, stirring at a stirring speed of 300-400 rpm for 80-100 min while maintaining nitrogen purging and stirring, sequentially adding butyl acrylate, methyl methacrylate, methacrylamide, acrylamide, styrene-acrylate copolymer emulsion, ultraviolet absorber, and light stabilizer, heating the system to 58-62℃ and maintaining the temperature, stirring continuously for 40-60 min, preparing an initiator into a 5-10% aqueous solution with deionized water, slowly adding it dropwise to the reaction system, controlling the dropwise addition time to 30-45 min, stopping heating after the reaction, cooling the system to below 40℃, adding nano-silica and nano-tin antimony oxide@PDA composite microspheres for reaction, and finally coating the product onto a paper layer after filtration and discharge.

[0014] This invention utilizes a two-step process to prepare nano-antimony tin oxide@PDA composite microspheres, followed by a synergistic addition of nanoparticles to optimize the dispersibility and interfacial bonding of nanoparticles in the adhesive layer. The PDA microspheres prepared in the first step serve as the core layer, exhibiting good biocompatibility and interfacial adhesion. After growing nano-antimony tin oxide on the PDA microspheres to form composite microspheres, the PDA shell improves the compatibility between the nano-antimony tin oxide and the acrylate polymer matrix, reducing nanoparticle aggregation in the adhesive layer. This is because the active groups in the PDA shell can interact with the polymer molecular chains, allowing the nanoparticles to better integrate into the matrix and achieve uniform dispersion. Simultaneously, the PDA shell also possesses additional antioxidant properties, further enhancing the stability of the adhesive layer. The subsequent addition of nanoparticles avoids interference with the monomer polymerization reaction that occurs before polymerization. During the polymerization reaction, the monomer polymerization requires specific reaction conditions and processes. If nanoparticles are added prematurely, they may adsorb monomers or initiators, affecting the polymerization rate and molecular weight distribution, leading to a decline in the adhesive layer's performance. The subsequent addition process ensures the integrity of the polymerization reaction and the uniformity of molecular weight distribution, thereby guaranteeing high initial strength of the adhesive layer. After the polymerization reaction is complete, nanoparticles are added. At this point, the matrix has already formed a certain network structure, allowing the nanoparticles to be better embedded in the matrix and form a good interfacial bond, further improving the performance of the adhesive layer. This synergistic effect of coating and post-addition optimizes the microstructure of the adhesive layer in terms of both nanoparticle dispersion and interfacial bonding, thereby enhancing the overall performance of the adhesive layer.

[0015] Furthermore, the nano-silica and nano-tin antimony oxide@PDA composite microspheres are dispersed at a stirring speed of 400-600 rpm for 120-140 min.

[0016] On the other hand, the method for preparing weather-resistant paper self-adhesive or weather-resistant paper self-adhesive in this invention is applied to the preparation of removable stickers.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention utilizes a two-step method to construct nano-antimony tin oxide@PDA composite microspheres as the core functional filler, achieving synergistic effects of ultraviolet shielding, free radical quenching, and near-infrared reflection. The first step involves preparing PDA microspheres as the core layer. Polydopamine possesses abundant phenolic hydroxyl and amino groups, which can absorb ultraviolet light and dissipate the energy of ultraviolet rays as heat or other forms of energy, effectively reducing direct ultraviolet radiation to the adhesive layer, lowering the probability of photochemical reactions induced by ultraviolet light, and inhibiting problems such as brittleness and decreased adhesion caused by continuous ultraviolet radiation. The second step involves growing nano-antimony tin oxide (ATO) on the PDA microspheres to form a shell. Nano-antimony tin oxide (ATO) possesses highly efficient near-infrared reflective properties, reflecting the near-infrared portion of sunlight, reducing heat absorption by the adhesive layer, and mitigating the negative impact of temperature increases on the adhesive layer's performance. Simultaneously, the conductive and heat-dissipating properties of ATO help to promptly conduct away the heat generated within the adhesive layer, preventing stress concentration and microcracks caused by drastic temperature changes. This composite structure, which first constructs a PDA core layer with UV absorption function and then grows an ATO shell layer with thermal protection function on its surface, fully leverages the advantages of both in UV and thermal aging protection, achieving synergistic effects and providing top-level UV and thermal aging protection for the adhesive layer.

[0019] In this invention, nano-tin-antimony oxide@PDA composite microspheres and nano-silica work synergistically as functional and reinforcing fillers to enhance the overall performance of the adhesive layer. Nano-silica possesses a high specific surface area and excellent reinforcing properties, allowing it to be uniformly dispersed within the acrylate polymer matrix and forming a good interfacial bond. Its surface silanol groups can interact physically or chemically with the polymer molecular chains, enhancing the intermolecular forces and thus increasing the cohesive strength of the adhesive layer, making it less prone to breakage under external forces. Simultaneously, nano-silica improves the heat resistance of the adhesive layer, reducing deformation and edge peeling caused by temperature increases. Meanwhile, the nano-tin-antimony oxide@PDA composite microspheres primarily provide UV and heat aging protection; their unique structure effectively blocks UV rays and heat from damaging the adhesive layer. Together, nano-silica provides a stable mechanical foundation for the adhesive layer, while the nano-tin-antimony oxide@PDA composite microspheres protect it from the adverse effects of UV rays and heat, ensuring the adhesive layer maintains good performance and service life during long-term outdoor use. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that the raw materials are all commercially available. Polyvinyl alcohol was purchased from Alfaesa (Tianjin) Chemical Co., Ltd., with a number average molecular weight of 60,000; styrene-acrylate copolymer emulsion, CAS No.: 25586-20-3, was purchased from Hebei Yanbang Chemical Technology Co., Ltd.

[0021] Example 1

[0022] This embodiment provides a weather-resistant self-adhesive for paper, including an adhesive layer comprising the following raw materials in parts by weight: 42 parts butyl acrylate, 32 parts methyl methacrylate, 0.6 parts polyvinyl alcohol, 4.5 parts methacrylamide, 5 parts acrylamide, 62 parts styrene-acrylate copolymer emulsion, 3.5 parts nano silica, 17 parts nano antimony tin oxide@PDA composite microspheres, 2.2 parts initiator, 1 part ultraviolet absorber, 0.35 parts light stabilizer, and 185 parts deionized water;

[0023] The preparation method of nano-tin antimony oxide@PDA composite microspheres includes: dissolving 1g of dopamine hydrochloride in 500mL of Tris-HCl buffer solution with pH=8.5, reacting at 25℃ and 250rpm for 23h, centrifuging at 10000rpm for 20min to collect the product, washing it three times alternately with deionized water and ethanol, dispersing it in deionized water to obtain a dispersion with a solid content of about 0.5%; then adding 0.5g of SnCl4·5H2O, 0.05g of SbCl3 and 2g of urea to 220mL of the dispersion in a 70℃ water bath, reacting at 70℃ for 7h, and centrifuging and washing after the reaction is completed to obtain the final product;

[0024] The initiator is ammonium persulfate; the ultraviolet absorber is BASF UV327; and the light stabilizer is the hindered amine light stabilizer Chimassorb 2020.

[0025] A method for preparing weather-resistant self-adhesive for paper includes the following steps: mixing deionized water and polyvinyl alcohol according to mass proportions, purging with high-purity nitrogen to remove oxygen from the system, stirring at 350 rpm for 90 min while maintaining nitrogen purging and stirring, sequentially adding butyl acrylate, methyl methacrylate, methacrylamide, acrylamide, styrene-acrylate copolymer emulsion, UV absorber, and light stabilizer, heating the system to 60°C and maintaining the temperature, stirring continuously for 50 min, preparing an initiator into a 7% (mass concentration) aqueous solution with deionized water, the total amount of water used in the adhesive layer preparation process being the formula amount, slowly adding it dropwise to the reaction system, controlling the dropwise addition time to 40 min, stopping heating after the reaction, cooling the system to 30°C, adding nano-silica and nano-tin antimony oxide@PDA composite microspheres, dispersing at 500 rpm for 130 min, and finally filtering and coating the product onto a paper layer.

[0026] Example 2

[0027] This embodiment provides a weather-resistant self-adhesive for paper, including an adhesive layer. The adhesive layer comprises the following raw materials in parts by weight: 40 parts butyl acrylate, 30 parts methyl methacrylate, 0.5 parts polyvinyl alcohol, 4 parts methacrylamide, 4 parts acrylamide, 60 parts styrene-acrylate copolymer emulsion, 3 parts nano silica, 16 parts nano tin antimony oxide@PDA composite microspheres, 2.0 parts initiator, 0.8 parts ultraviolet absorber, 0.3 parts light stabilizer, and 180 parts deionized water.

[0028] The preparation method of nano-tin antimony oxide@PDA composite microspheres includes: dissolving 0.8g of dopamine hydrochloride in 450mL of Tris-HCl buffer solution with pH=8.5, reacting at 20℃ and 200rpm for 22h, centrifuging at 10000rpm for 20min to collect the product, washing it three times alternately with deionized water and ethanol, dispersing it in deionized water to obtain a dispersion with a solid content of about 0.4%; then adding 0.4g of SnCl4·5H2O, 0.04g of SbCl3 and 1.8g of urea to 200mL of the dispersion in a water bath at 65℃, reacting at 65℃ for 6h, and centrifuging and washing after the reaction is completed to obtain the final product;

[0029] The initiator is ammonium persulfate; the ultraviolet absorber is BASF UV327; and the light stabilizer is the hindered amine light stabilizer Chimassorb 2020.

[0030] A method for preparing a weather-resistant self-adhesive for paper includes the following steps: mixing deionized water and polyvinyl alcohol according to mass proportions, purging with high-purity nitrogen to remove oxygen from the system, stirring at 300 rpm for 80 min while maintaining nitrogen purging and stirring, sequentially adding butyl acrylate, methyl methacrylate, methacrylamide, acrylamide, styrene-acrylate copolymer emulsion, UV absorber, and light stabilizer, heating the system to 58°C and maintaining the temperature, stirring continuously for 40 min, preparing an initiator into a 5% aqueous solution with deionized water, the total amount of water used in the adhesive layer preparation process being the formula amount, slowly adding it dropwise to the reaction system, controlling the dropwise addition time to 30 min, stopping heating after the reaction, cooling the system to 30°C, adding nano-silica and nano-tin antimony oxide@PDA composite microspheres, dispersing at 400 rpm for 120 min, and finally filtering and coating the product onto a paper layer.

[0031] Example 3

[0032] This embodiment provides a weather-resistant self-adhesive for paper, including an adhesive layer comprising the following raw materials in parts by weight: 45 parts butyl acrylate, 35 parts methyl methacrylate, 0.7 parts polyvinyl alcohol, 5 parts methacrylamide, 6 parts acrylamide, 65 parts styrene-acrylate copolymer emulsion, 4 parts nano silica, 18 parts nano tin oxide antimony@PDA composite microspheres, 2.5 parts initiator, 1.2 parts ultraviolet absorber, 0.4 parts light stabilizer, and 190 parts deionized water;

[0033] The preparation method of nano-tin antimony oxide@PDA composite microspheres includes: dissolving 1.2g of dopamine hydrochloride in 550mL of Tris-HCl buffer solution with pH=8.5, reacting at 30℃ and 300rpm for 24h, centrifuging at 10000rpm for 20min to collect the product, washing it three times alternately with deionized water and ethanol, dispersing it in deionized water to obtain a dispersion with a solid content of about 0.6%; then adding 0.6g of SnCl4·5H2O, 0.06g of SbCl3 and 2.2g of urea to 250mL of the dispersion in a water bath at 75℃, reacting at 75℃ for 8h, and centrifuging and washing after the reaction is completed to obtain the final product;

[0034] The initiator is ammonium persulfate; the ultraviolet absorber is BASF UV327; and the light stabilizer is the hindered amine light stabilizer Chimassorb 2020.

[0035] A method for preparing a weather-resistant self-adhesive for paper includes the following steps: mixing deionized water and polyvinyl alcohol according to mass proportions, purging with high-purity nitrogen to remove oxygen from the system, stirring at 400 rpm for 100 min while maintaining nitrogen purging and stirring, sequentially adding butyl acrylate, methyl methacrylate, methacrylamide, acrylamide, styrene-acrylate copolymer emulsion, UV absorber, and light stabilizer, heating the system to 62°C and maintaining the temperature, stirring continuously for 60 min, preparing an initiator into a 10% aqueous solution with deionized water, the total amount of water used in the adhesive layer preparation process being the formula amount, slowly adding it dropwise to the reaction system, controlling the dropwise addition time to 45 min, stopping heating after the reaction, cooling the system to below 40°C, adding nano-silica and nano-tin antimony oxide@PDA composite microspheres, dispersing at 600 rpm for 140 min, and finally filtering and coating the product onto a paper layer.

[0036] Comparative Example 1

[0037] Unlike Example 1, this comparative example did not include nano-tin antimony oxide@PDA composite microspheres; otherwise, it was the same as Example 1.

[0038] Comparative Example 2

[0039] Unlike Example 1, in this comparative example, the nano-tin antimony oxide@PDA composite microspheres were replaced with hollow polydopamine microspheres of equal mass. The preparation method was as follows: 1 g of dopamine hydrochloride was dissolved in 500 mL of Tris-HCl buffer solution with pH=8.5, reacted at 25°C and 250 rpm for 23 h, centrifuged at 10000 rpm for 20 min to collect the product, and washed three times alternately with deionized water and ethanol. The rest was the same as in Example 1.

[0040] Comparative Example 3

[0041] Unlike Example 1, in this comparative example, nano-tin antimony oxide@PDA composite microspheres were replaced with an equal mass of nano-tin antimony oxide. The preparation method was as follows: 0.5g SnCl4·5H2O, 0.05g SbCl3 and 2g urea were added to 220mL of deionized water in a water bath at 70℃. The reaction was carried out at 70℃ for 7h. After the reaction was completed, the product was obtained by centrifugation and washing. The rest was the same as in Example 1.

[0042] Comparative Example 4

[0043] Unlike Example 1, in this comparative example, the nano-tin antimony oxide@PDA composite microspheres were replaced with an equal mass of modified nano-titanium dioxide. The preparation method was as follows: 4 parts of hexamethyldisilazane, 6 parts of 3-aminopropyltrimethoxysilane, 4 parts of tetraethoxysilane, and 200 parts of anhydrous ethanol were thoroughly mixed to prepare a mixed modifier. 100 parts of nano-titanium dioxide with a particle size of 10 nm and 200 parts of the mixed modifier were thoroughly mixed at room temperature for 55 min, ultrasonicated at room temperature for 1.6 h, and then transferred to a vacuum mixer. The mixture was heated to 85 °C and refluxed at -0.5 MPa for 4.5 h. Finally, the ethanol was removed under reduced pressure, and the mixture was dried to obtain modified nano-titanium dioxide. The rest of the process was the same as in Example 1.

[0044] Comparative Example 5

[0045] Unlike Example 1, no nano-silica was added in this comparative example; otherwise, it was the same as Example 1.

[0046] Comparative Example 6

[0047] Unlike Example 1, in this comparative example, nano-silica and nano-tin antimony oxide@PDA composite microspheres were added to the aqueous phase before the reaction began, dispersed together with polyvinyl alcohol, and then polymerized. Specifically, deionized water, polyvinyl alcohol, nano-silica, and nano-tin antimony oxide@PDA composite microspheres were mixed according to mass fractions, high-purity nitrogen was introduced to remove oxygen from the system, and the mixture was stirred at 350 rpm for 90 min while maintaining nitrogen purging and stirring. Butyl acrylate, methyl methacrylate, and methyl methacrylate were added sequentially. Acrylamide, acrylamide, styrene-acrylate copolymer emulsion, UV absorber, and light stabilizer were used to heat the system to 60°C and maintain the temperature for 50 minutes. The initiator was prepared into a 7% aqueous solution with deionized water. The total amount of water used in the preparation of the adhesive layer was the amount specified in the formula. The water was slowly added dropwise to the reaction system, and the addition time was controlled to be 40 minutes. After the reaction was completed, the heating was stopped, and the system was cooled to 30°C. Finally, the product was filtered, discharged, and coated onto a paper layer to obtain the final product. The rest was the same as in Example 1.

[0048] Experimental Example 1: The performance of the self-adhesive paper for weather-resistant paper prepared in Examples 1-3 and Comparative Examples 1-6 was investigated.

[0049] Stability: Take the self-adhesive labels prepared by each embodiment and each comparative example with a size of 150mm×75mm, and after placing them in a natural environment for 9 months and 18 months, carefully peel the self-adhesive labels off the backing paper and observe whether the adhesive surface becomes brittle, sticky, has cohesive failure, micro-cracks or macro-cracking.

[0050] High temperature stability: Take the self-adhesive labels prepared by each example and each comparative example with a size of 150mm×75mm, place them at 120℃ for 1 month, and observe whether there is any phenomenon of peeling or falling off.

[0051] Peel strength and peel strength after aging: The 180° peel strength was tested according to GB / T2792, and the test was conducted in an accelerated UV aging chamber with an irradiation intensity of 1.5 kWh / m². 2 Peel strength at 180° after 2000 hours of UV irradiation at 65°C;

[0052] The performance test results are shown in Table 1 below:

[0053] Table 1: Performance Tests

[0054]

[0055] Based on the table above, the initial peel strength of Examples 1-3 all reached a high level of approximately 800 N / m, and the strength retention rate after 2000 hours of UV aging was close to 90%, demonstrating extremely excellent durability and UV stability. The adhesive layer remained intact without significant defects during long-term natural aging and high-temperature testing, proving the perfect synergistic effect of the nano-tin antimony oxide@PDA composite microspheres, nano-silica, and the acrylate polymer matrix.

[0056] Comparative Example 1, lacking nano-tin antimony oxide@PDA composite microspheres, lacked key UV shielding and free radical quenching components, resulting in severe degradation of the colloid under UV light. This manifested as brittleness and macroscopic cracking of the adhesive layer, with a sharp decrease in peel strength retention to approximately 64% after aging. This confirms that nano-tin antimony oxide@PDA composite microspheres are the core functional filler that imparts excellent weather resistance to the adhesive layer.

[0057] In Comparative Example 2, the hollow PDA microspheres only provided limited UV absorption and physical barrier effects, but lacked the efficient near-infrared reflection and conductive heat dissipation properties of antimony tin oxide. Its photostable performance was far inferior to the nano-antimony tin oxide@PDA composite structure. After aging, the strength retention rate was only 70%, and microcracks appeared, proving that the key role of nano-antimony tin oxide is irreplaceable.

[0058] In Comparative Example 3, the uncoated nano-ATO particles tended to aggregate in the adhesive layer, exhibiting poor compatibility with the matrix and forming stress defect points (microcracks). Furthermore, lacking the interfacial adhesion and additional antioxidant function of the PDA shell, its performance was even slightly lower than that of hollow PDA microspheres, with a retention rate of 67.5%. This demonstrates that PDA coating is crucial for improving nanoparticle dispersibility, enhancing interfacial bonding, and providing synergistic stabilization.

[0059] Although the modification of nano-silica in Comparative Example 4 reduced its photocatalytic activity and provided some UV shielding, it still exhibited some photocatalytic activity under UV light, potentially causing a slow degradation of the organic adhesive layer. Its performance was superior to the blank and pure tin-antimony oxide groups, but significantly lower than the nano-tin-antimony oxide@PDA composite structure, demonstrating that nano-tin-antimony oxide@PDA offers superior overall protective performance compared to traditional modified nano-silica.

[0060] The lack of nano-silica in Comparative Example 5 resulted in a decrease in the cohesive strength and heat resistance of the adhesive layer. This manifested as "cohesive failure" (i.e., the colloid itself breaks) after aging, and the layer was prone to curling and detachment at high temperatures. The low strength retention rate after aging (65%) demonstrates that nano-silica plays a crucial role in enhancing the mechanical properties of the colloid and preventing high-temperature deformation, and is functionally complementary to nano-tin antimony oxide@PDA.

[0061] Comparative Example 6, where nanoparticles were added before polymerization, severely interfered with the monomer polymerization process, potentially leading to uneven molecular weight distribution and insufficient cross-linking, resulting in numerous inherent defects in the adhesive layer. Consequently, it exhibited the lowest initial strength and the worst results in all aging tests (natural, high temperature, and UV), showing severe cracking and peeling. This conversely demonstrates that the post-addition of nanoparticles is crucial for ensuring the integrity of the polymerization reaction and the final adhesive layer performance.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention; those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A weather-resistant self-adhesive for paper, characterized in that, The adhesive layer comprises the following raw materials in parts by weight: 40-45 parts butyl acrylate, 30-35 parts methyl methacrylate, 0.5-0.7 parts polyvinyl alcohol, 4-5 parts methacrylamide, 4-6 parts acrylamide, 60-65 parts styrene-acrylate copolymer emulsion, 3-4 parts nano-silica, 16-18 parts nano-tin antimony oxide@PDA composite microspheres, 2.0-2.5 parts initiator, 0.8-1.2 parts ultraviolet absorber, 0.3-0.4 parts light stabilizer, and 180-190 parts deionized water. The preparation steps of the adhesive layer include: mixing deionized water and polyvinyl alcohol according to the specified parts by weight, introducing high-purity nitrogen gas to remove oxygen from the system, and stirring at a speed of 30... Stir at 0-400 rpm for 80-100 min while maintaining nitrogen purging and stirring. Add butyl acrylate, methyl methacrylate, methacrylamide, acrylamide, styrene-acrylate copolymer emulsion, UV absorber, and light stabilizer in sequence. Heat the system to 58-62℃ and maintain the temperature. Stir continuously for 40-60 min. Prepare an aqueous solution of initiator with deionized water to a mass concentration of 5-10%, and slowly add it dropwise to the reaction system, controlling the dropwise addition time to 30-45 min. After the reaction is completed, stop heating and cool the system to below 40℃. Add nano-silica and nano-tin antimony oxide@PDA composite microspheres to react. Finally, filter and discharge the product and coat it onto a paper layer to obtain the final product.

2. The weather-resistant self-adhesive for paper according to claim 1, characterized in that, The preparation method of the nano-tin antimony oxide@PDA composite microspheres includes: dissolving dopamine hydrochloride in Tris-HCl buffer solution with pH=8.0-9.0, reacting at 20-30℃ and 200-300rpm for 22-24h, collecting the product by centrifugation, dispersing it in deionized water to obtain a dispersion with a solid content of 0.4%-0.6%; then adding SnCl4·5H2O, SbCl3 and urea in a water bath at 65-75℃, reacting at 65-75℃ for 6-8h, and centrifuging and washing after the reaction is completed to obtain the final product.

3. The self-adhesive label for weather-resistant paper according to claim 2, characterized in that, The ratio of dopamine hydrochloride to Tris-HCl buffer is 0.8-1.2 g: 450-550 mL.

4. The self-adhesive label for weather-resistant paper according to claim 2, characterized in that, The ratio of the dispersion, SnCl4·5H2O, SbCl3 and urea is 200-250mL: 0.4-0.6g: 0.04-0.06g: 1.8-2.2g.

5. The weather-resistant self-adhesive for paper according to claim 1, characterized in that, The initiator is ammonium persulfate.

6. The weather-resistant self-adhesive for paper according to claim 1, characterized in that, The ultraviolet absorber is BASF UV327.

7. The self-adhesive label for weather-resistant paper according to claim 1, characterized in that, The light stabilizer is the hindered amine light stabilizer Chimassorb 2020.

8. A method for preparing a weather-resistant self-adhesive for paper as described in any one of claims 1-7, characterized in that, The adhesive layer preparation steps include: mixing deionized water and polyvinyl alcohol according to the mass ratio, purging with high-purity nitrogen to remove oxygen from the system, stirring at a stirring speed of 300-400 rpm for 80-100 min while maintaining nitrogen purging and stirring, sequentially adding butyl acrylate, methyl methacrylate, methacrylamide, acrylamide, styrene-acrylate copolymer emulsion, ultraviolet absorber, and light stabilizer, heating the system to 58-62℃ and maintaining the temperature, stirring continuously for 40-60 min, preparing an initiator into a 5-10% aqueous solution with deionized water, slowly adding it dropwise to the reaction system, controlling the dropwise addition time to 30-45 min, stopping heating after the reaction, cooling the system to below 40℃, adding nano-silica and nano-tin antimony oxide@PDA composite microspheres for reaction, and finally coating the product onto a paper layer after filtration and discharge.

9. The method for preparing weather-resistant self-adhesive paper according to claim 8, characterized in that, The nano-silica and nano-tin antimony oxide@PDA composite microspheres were dispersed at a stirring speed of 400-600 rpm for 120-140 min.

10. The use of the weather-resistant paper self-adhesive as described in any one of claims 1-7 in the preparation of removable stickers.

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