High-efficiency durable water-resistant sandpaper suitable for humid environment and preparation method thereof

Abstract

The application discloses a kind of high-efficient durable water-resistant sandpaper suitable for humid environment and preparation method thereof, and high-efficient durable water-resistant sandpaper includes substrate layer, adhesive layer, abrasive layer;Adhesive layer is located in one side of substrate layer, and is formed by resin composition curing;Abrasive layer is formed by abrasive distribution, and one end of abrasive is embedded in adhesive layer;Abrasive surface has porous water-resistant interface layer formed by zinc imidazole ester frame;The porous water-resistant interface layer is obtained by forming zinc imidazole ester frame by the reaction of abrasive in zinc nitrate and 2-methyl imidazole methanol solution, whereby the sandpaper of the present application is through the synergistic effect of mechanical interlocking, chemical bonding, hydrophobic inhibition and stress buffering between abrasive and adhesive layer, solve the problem that abrasive and adhesive layer combination interface of sandpaper are softened by water, leading to non-normal shedding of abrasive, service life is reduced, and polishing effect is poor, so that the sandpaper of the present application has the polishing performance of adapting to humid environment, high efficiency and durability.

Description

Technical Field

[0001] This application relates to sanding work in humid environments, and more particularly to a high-efficiency, durable, and water-resistant sandpaper suitable for humid environments and a method for preparing the same. Background Technology

[0002] Sandpaper is a very common polishing consumable. It consists of a substrate layer made of composite paper or cloth, an adhesive layer on one side of the substrate layer coated with a resin composition and cured, and an abrasive layer composed of abrasive particles embedded in the adhesive layer on the side facing away from the substrate layer. The abrasive particles are generally silicon carbide or diamond, which have high hardness.

[0003] In actual use and research and development experiments, the applicant found that sandpaper made of traditional resin-bonded abrasives has problems such as easy abrasive detachment, low sanding efficiency, and short service life when sanding in humid environments.

[0004] Research revealed that the reason lies in the bonding interface between the abrasive particles and the resin. Due to the different materials on both sides, this interface itself is a weak point in the bond between the adhesive layer and the abrasive layer. The bending deformation during sanding makes it easier for cracks to form at the interface. In humid environments, moisture and liquids can easily penetrate into these gaps, exacerbating the tearing and extension of the gaps when subjected to external forces during sanding. Furthermore, the resin composition swells after absorbing water, leading to a decrease in the bonding strength at the interface. Even without sanding use, simply storing the sander in a humid environment will reduce sanding efficiency and its lifespan.

[0005] Therefore, the applicant hopes to develop a high-efficiency, durable, and water-resistant sandpaper suitable for humid environments. Summary of the Invention

[0006] To address the issues of low sanding efficiency and short service life of existing sandpaper in humid environments, a high-efficiency, durable, and water-resistant sandpaper suitable for humid environments and its preparation method are provided.

[0007] The first inventive objective of this invention is achieved through the following technical solution: A high-efficiency, durable, and water-resistant sandpaper suitable for humid environments, comprising a substrate layer, an adhesive layer, and an abrasive layer; The adhesive layer is located on one side of the substrate layer and is formed by curing a resin composition. The abrasive layer is formed by the distribution of abrasive particles, with one end of the abrasive particles embedded in the bonding layer; The abrasive surface has a porous, water-resistant interface layer formed by a zinc imidazole ester framework; The porous water-resistant interface layer is obtained by reacting abrasives in a methanol solution of zinc nitrate and 2-methylimidazole to form a zinc imidazole ester framework.

[0008] By adopting the above technical solution, the porous water-resistant interface layer on the surface of the abrasive has a hierarchical pore structure composed of micropores of 0.3~0.4nm and mesopores of 2~50nm. The resin of the bonding layer can penetrate into the hierarchical pore structure and solidify to form a nano-anchoring structure. The mechanical locking force between the abrasive and the bonding layer is significantly improved compared with the planar interface bonding force of the prior art, thereby enhancing the bonding strength between the abrasive and the bonding layer from the physical structure. In this application, the porous water-resistant interface layer is composed of a zinc imidazole ester framework. The 2-methylimidazolium ligand in the zinc imidazole ester contains a nitrogen atom with a lone pair of electrons, which can undergo a nucleophilic ring-opening reaction with the epoxy group of the epoxy resin to form a covalent bond. At the same time, the zinc nodes form coordination bonds with the hydroxyl or carboxyl groups in the resin, thereby improving the bonding strength between the abrasive and the adhesive layer from a chemical perspective. Compared to traditional methods that rely on physical adsorption and hydrogen bonding, the abrasive in this application significantly enhances its bonding force through the synergistic effect of mechanical interlocking of covalent and coordination bonds, and the strength of the bonding interface is significantly improved in terms of resistance to humid heat aging. In addition, the pores on the porous water-resistant interface layer are slightly larger than the dynamic diameter of water molecules, but its surface hydrophobicity means that water only needs to overcome a high energy barrier to wet and penetrate through a small contact angle. This prevents water from wetting the interface between the abrasive and the bonding layer, and can play a role in preventing water from softening the interface. The elastic modulus of zinc imidazole ester is based on the relationship between the abrasive and the resin, which can alleviate stress concentration caused by abrupt changes in modulus and reduce the possibility of abrasive shedding. Therefore, the sandpaper of this application solves the problems of abnormal abrasive detachment, reduced service life, and poor sanding effect caused by the softening of the interface between the abrasive and the bonding layer due to water through the synergistic effects of mechanical interlocking, chemical bonding, hydrophobic inhibition, and stress buffering between the abrasive and the bonding layer. This enables the sandpaper of this application to have sanding performance that is adaptable to humid environments, efficient, and durable.

[0009] Optionally, the preparation process of the porous water-resistant interface layer is as follows: Zinc nitrate is dissolved in methanol to obtain a methanol solution of zinc nitrate, and 2-methylimidazole is dissolved in methanol to obtain a methanol solution of 2-methylimidazole. The abrasive was added to a methanol solution of zinc nitrate and dispersed evenly. While stirring, a methanol solution of 2-methylimidazole was slowly added dropwise. The reaction was carried out at room temperature for 6 hours with a stirring speed of 50-100 rpm to prevent the abrasive from piling up and depositing. After the reaction was complete, the abrasive was washed with methanol and then vacuum dried at a temperature below 80°C to obtain an abrasive with a porous, water-resistant interface layer.

[0010] By adopting the above technical solution, this application selects methanol as the solvent for zinc nitrate and 2-methylimidazole. Compared with water, methanol has moderate polarity and suitable solubility, and it is less likely to cause excessive growth of porous water-resistant interface layer compared with water. Adding a methanol solution of 2-methylimidazole dropwise can effectively control the reaction rate and precisely control the crystallinity of zinc imidazole ester, thereby accurately adjusting the thickness of the porous water-resistant interface layer. Controlling the rotation speed can prevent abrasive settling and reduce the peeling of the porous water-resistant interface layer caused by particle collision. Drying is carried out under vacuum at a temperature below 80°C to avoid the collapse of the zinc imidazole ester framework due to excessive temperature, thus ensuring the integrity of the subsequently obtained porous water-resistant interface layer.

[0011] Optionally, the molar ratio of zinc ions to 2-methylimidazole is 1:4 during the preparation of the porous water-resistant interface layer.

[0012] By adopting the above technical solution, a slight excess of 2-methylimidazole ensures complete coordination of zinc ions. Furthermore, the zinc imidazole ester obtained at this molar ratio exhibits superior crystallinity, better resin penetration, stronger interfacial bonding, and better waterproof performance.

[0013] Optionally, the abrasive may be surface modified with an aminosilane coupling agent before the porous water-resistant interface layer is prepared.

[0014] By adopting the above technical solution, amino groups are first introduced on the surface of the abrasive, and then zinc imidazole ester is grown. The amino groups can enhance the adsorption of zinc ions by the abrasive, improve the nucleation density and uniformity of zinc imidazole ester, and enhance its interfacial bonding strength.

[0015] Optionally, the aminosilane coupling agent is γ-aminopropyltriethoxysilane.

[0016] By adopting the above technical solution, the treatment effect is better when selecting this aminosilane coupling agent.

[0017] Optionally, the pH is maintained at 7.5-8 during the reaction.

[0018] By adopting the above technical solution, the zinc imidazole ester obtained under this pH environment has both excellent crystal fineness and crystallization rate and fewer impurities. If the pH is too low, zinc ions are easy to combine with hydroxide ions to form zinc oxide impurities, which are mixed into the porous water-resistant interface layer, resulting in a decrease in interface performance. If the pH is too high, 2-methylimidazolium will be deprotonated too quickly, resulting in zinc imidazole ester crystallizing too quickly and becoming coarse and loose, with poor interface performance.

[0019] Optionally, polyvinylpyrrolidone is also added to the methanol solution of zinc nitrate.

[0020] By adopting the above technical solution, the viscosity of the methanol solution of zinc nitrate can be increased, thereby reducing the required stirring speed and reducing the peeling of the porous water-resistant interface layer caused by the impact of abrasive particles.

[0021] The second objective of this invention is achieved through the following technical solution: A method for preparing high-efficiency, durable, and water-resistant sandpaper suitable for humid environments includes the following steps: A resin curing agent is coated on one side of the substrate layer, and then pre-cured to form a semi-hardened layer; Abrasives are used to implant sand onto the semi-hardened layer to form a sand-implanted layer. A resin composition is coated a second time onto the sand layer, and then cured in stages to finally obtain sandpaper.

[0022] By adopting the above technical solution, the abrasive has been modified and adjusted, and the original paper and preparation process can be used. This method is simple, fast, and has low technical improvement costs.

[0023] In summary, this application has at least the following beneficial effects: The sandpaper of this application solves the problems of abnormal abrasive shedding, reduced service life, and poor sanding effect caused by the softening of the interface between the abrasive and the bonding layer due to water through the synergistic effects of mechanical interlocking, chemical bonding, hydrophobic inhibition, and stress buffering between the abrasive and the bonding layer. This enables the sandpaper of this application to have sanding performance that is adaptable to humid environments, efficient, and durable. Detailed Implementation

[0024] Preparation Example 1 An abrasive, the preparation method of which is as follows: According to abrasive standards, silicon carbide abrasive grains with a particle size distribution of 20~50μm and D50=35μm were selected as abrasive raw materials. The abrasive material was added to a solution of acetone and ethanol in a 1:1 volume ratio, ultrasonically cleaned at 40 kHz for 30 min, filtered and dried to obtain the cleaned abrasive grains. 0.01 mol of zinc nitrate hexahydrate was added to 100 ml of methanol and magnetically stirred until completely dissolved and the solution became clear, thus obtaining a methanol solution of zinc nitrate, hereinafter referred to as solution A. Add 0.04 mol of 2-methylimidazole to another 100 ml of methanol and stir until completely dissolved to obtain a methanol solution of 2-methylimidazole, hereinafter referred to as solution B. Add 100g of cleaned abrasive particles to solution A and disperse them using ultrasound at 40kHz 200W for 10min. Then, continue stirring at 80rpm while adding solution B dropwise at a rate of 1ml / min. Maintain the liquid phase temperature at 25±2℃. Add triethylamine during the dropwise addition to adjust the pH of the liquid phase to a stable value of 7.7±0.2. Continue stirring and reacting for 120min until the dropwise addition is complete. Then, add cold methanol (0℃) to dilute the liquid phase and cool it to 4℃. Let it stand for 3h. After filtration, the filtered material was washed with methanol and then vacuum dried at 60°C for 12 hours to obtain the abrasive.

[0025] Preparation Example 2 An abrasive, the preparation method of which is as follows: According to abrasive standards, silicon carbide abrasive grains with a particle size distribution of 20~50μm and D50=35μm were selected as abrasive raw materials. The abrasive material was added to a solution of acetone and ethanol in a 1:1 volume ratio, ultrasonically cleaned at 40 kHz for 30 min, filtered and dried to obtain the cleaned abrasive grains. Octyltrioxysilane and ethanol were mixed at a volume ratio of 1:9, then water of the same molar amount as octyltrioxysilane was added, and acetic acid was added dropwise to adjust the pH to 4.5. The mixture was stirred for 30 minutes to obtain the reaction liquid phase. The cleaned abrasive particles were added to the reaction liquid phase at a solid-liquid ratio of 1:10, and the mixture was stirred and reacted in a 70°C water environment for 3 hours. The material was filtered and washed with ethanol. After washing, it was vacuum dried at 60°C for 12 hours to obtain the abrasive.

[0026] Preparation Example 3 An abrasive, based on Preparation Example 1, differs in that liquid A and liquid B are prepared using water as a solvent, i.e. Solution A is prepared by adding 0.01 mol of zinc nitrate hexahydrate to 100 ml of water and stirring magnetically until completely dissolved and the solution becomes transparent. Solution B is prepared by adding 0.04 mol of 2-methylimidazole to another 100 ml of water and stirring until completely dissolved.

[0027] Preparation Example 4 An abrasive, based on Preparation Example 1, differs in that the stirring speed is 150 rpm during the droplet addition of liquid B to liquid A, and the sedimentation and deposition of abrasive particles can be clearly observed during the preparation process.

[0028] Preparation Example 5 An abrasive, based on Preparation Example 1, differs in that the stirring speed is 40 rpm during the droplet addition of liquid B to liquid A, and the sedimentation and deposition of abrasive particles can be clearly observed during the preparation process.

[0029] Preparation Example 6 An abrasive, the preparation method of which is as follows: According to abrasive standards, silicon carbide abrasive grains with a particle size distribution of 20~50μm and D50=35μm were selected as abrasive raw materials. The abrasive material was added to a solution of acetone and ethanol in a 1:1 volume ratio, ultrasonically cleaned at 40 kHz for 30 min, filtered and dried to obtain the cleaned abrasive grains. 0.01 mol of zinc nitrate hexahydrate was added to 100 ml of methanol and magnetically stirred until completely dissolved and the solution became clear, thus obtaining a methanol solution of zinc nitrate, hereinafter referred to as solution A. Add 0.04 mol of 2-methylimidazole to another 100 ml of methanol and stir until completely dissolved to obtain a methanol solution of 2-methylimidazole, hereinafter referred to as solution B. Add 100g of cleaned abrasive particles to solution A and disperse them using ultrasound at 40kHz 200W for 10min. Then, continue stirring at 80rpm while pouring solution B directly into the solution. The addition time of solution B should be less than 10 seconds. Maintain the liquid phase temperature at 25±2℃ and add triethylamine dropwise to adjust the pH of the liquid phase to a stable value of 7.7±0.2. Continue stirring and react for 120min. Then, add cold methanol (0℃) to dilute the liquid phase and cool it to 4℃. Let it stand for 3h. After filtration, the filtered material was washed with methanol and then vacuum dried at 60°C for 12 hours to obtain the abrasive.

[0030] During the preparation process, it was clearly observed that the abrasive particles agglomerated within 5 to 15 minutes after the addition of liquid B, and the agglomerated abrasive particles deposited and settled within 40 to 60 minutes.

[0031] Preparation Example 7 An abrasive, based on Preparation Example 1, differs in that solution B is prepared by adding 0.02 mol of 2-methylimidazole to another 100 ml of water and stirring until completely dissolved.

[0032] Preparation Example 8 An abrasive, based on Preparation Example 1, differs in that solution B is prepared by adding 0.03 mol of 2-methylimidazole to another 100 ml of water and stirring until completely dissolved.

[0033] Preparation Example 9 An abrasive, based on Preparation Example 1, differs in that solution B is prepared by adding 0.05 mol of 2-methylimidazole to another 100 ml of water and stirring until completely dissolved.

[0034] Preparation Example 10 An abrasive, based on Preparation Example 1, differs in that solution B is prepared by adding 0.06 mol of 2-methylimidazole to another 100 ml of water and stirring until completely dissolved.

[0035] Preparation Example 11 An abrasive, based on Preparation Example 1, differs in that during the addition of liquid B to liquid A, triethylamine is added dropwise to stabilize the pH of the liquid phase at 7.0 ± 0.2.

[0036] Preparation Example 12 An abrasive, based on Preparation Example 1, differs in that during the addition of liquid B to liquid A, triethylamine is added dropwise to stabilize the pH of the liquid phase at 7.5 ± 0.2.

[0037] Preparation Example 13 An abrasive, based on Preparation Example 1, differs in that during the addition of liquid B to liquid A, triethylamine is added dropwise to stabilize the pH of the liquid phase at 8.0 ± 0.2.

[0038] Preparation Example 14 An abrasive, based on Preparation Example 1, differs in that during the addition of liquid B to liquid A, triethylamine is added dropwise to stabilize the pH of the liquid phase at 8.5 ± 0.2.

[0039] Preparation Example 15 An abrasive, the preparation method of which is as follows: According to abrasive standards, silicon carbide abrasive grains with a particle size distribution of 20~50μm and D50=35μm were selected as abrasive raw materials. The abrasive material was added to a solution of acetone and ethanol in a 1:1 volume ratio, ultrasonically cleaned at 40 kHz for 30 min, filtered and dried to obtain the cleaned abrasive grains. Add 10g of γ-aminopropyltriethoxysilane to 490g of ethanol / water mixture (ethanol:water volume ratio 95:5), stir magnetically for 10min, add 0.1mol / L acetic acid dropwise until pH=4.5, continue stirring for 30min until the solution is clear, and obtain silane hydrolysate; Add 100g of cleaned abrasive particles to 500ml of silane hydrolysate and react in a 60℃ water bath with shaking (120rpm) for two hours. After centrifugation, the particles are first dried at 80℃ for 1 hour, and then heat-treated at 120℃ for 1 hour to obtain modified abrasive particles. 0.01 mol of zinc nitrate hexahydrate was added to 100 ml of methanol and magnetically stirred until completely dissolved and the solution became clear, thus obtaining a methanol solution of zinc nitrate, hereinafter referred to as solution A. Add 0.04 mol of 2-methylimidazole to another 100 ml of methanol and stir until completely dissolved to obtain a methanol solution of 2-methylimidazole, hereinafter referred to as solution B. The modified abrasive particles were added to solution A and dispersed by ultrasonication at 40kHz 200W for 10 minutes. Then, the mixture was stirred continuously at 80rpm while adding solution B dropwise at a rate of 1ml / min. The liquid phase temperature was maintained at 25±2℃. Triethylamine was added during the dropwise addition to adjust the pH of the liquid phase to a stable value of 7.7±0.2. The reaction was continued by stirring for 90 minutes until the dropwise addition was completed. Then, cold methanol (0℃) was added to dilute the liquid phase and the temperature was lowered to 4℃. The mixture was allowed to stand for 3 hours. After filtration, the filtered material was washed with methanol and then vacuum dried at 60°C for 12 hours to obtain the abrasive.

[0040] Preparation Example 16 An abrasive, based on Preparation Example 15, differs in that an equal mass of 3-aminopropyltrimethoxysilane is used instead of γ-aminopropyltriethoxysilane.

[0041] Preparation Example 17 An abrasive, based on Preparation Example 15, differs in that an equal mass of octyltrioxysilane is used instead of γ-aminopropyltriethoxysilane.

[0042] Preparation Example 18 An abrasive, based on Preparation Example 15, differs in that it is prepared by mixing and stirring 0.01 mol of zinc nitrate hexahydrate, 100 ml of methanol, and 4.92 g of polyvinylpyrrolidone in solution A, followed by dissolution of zinc nitrate hexahydrate. The polyvinylpyrrolidone comprises 5 wt%.

[0043] Examples 1-14 A high-efficiency, durable, and water-resistant sandpaper suitable for humid environments, comprising a substrate layer, an adhesive layer, and an abrasive layer.

[0044] The substrate layer is HL-802 type sandpaper base paper from Anhui Xiaoxian Hualong Special Paper Industry Co., Ltd., with a thickness of 125μm.

[0045] The adhesive layer is located on one side of the substrate layer and is formed by curing the resin composition. In Examples 1-14, the resin composition was obtained by uniformly mixing epoxy resin E44 and 50nm nano-silica at a mass ratio of 78:22.

[0046] The abrasive layer is formed by the distribution of abrasive particles, with one end of the abrasive particles embedded in the bonding layer. The sources of the abrasives used in Examples 1-14 are shown in Table 1 below.

[0047] The preparation method is as follows: A resin composition is coated on one side of the substrate layer to a thickness of 30 μm, and then a semi-cured layer is formed by UV pre-curing. Using electrostatic sand planting method, with a controlled voltage of 80kV, sand was planted on the semi-hardened layer, and the sand planting coverage rate was 92%, resulting in a sand-planted layer. Then, a resin composition is coated a second time on the sand layer to a thickness of 5μm. The mixture is then placed in a tunnel oven, preheated at 80℃ for 3 minutes, and then deeply crosslinked at 150℃ for 10 minutes to obtain sandpaper.

[0048] Comparative Examples 1-4 A high-efficiency, durable, and water-resistant sandpaper suitable for humid environments, comprising a substrate layer, an adhesive layer, and an abrasive layer.

[0049] The substrate layer is HL-802 type sandpaper base paper from Anhui Xiaoxian Hualong Special Paper Industry Co., Ltd., with a thickness of 125μm.

[0050] The adhesive layer is located on one side of the substrate layer and is formed by curing the resin composition. The resin compositions in Comparative Examples 1-4 were obtained by uniformly mixing epoxy resin E44 and 50nm nano-silica at a mass ratio of 78:22.

[0051] The abrasive layer is formed by the distribution of abrasive particles, with one end of the abrasive particles embedded in the bonding layer. The sources of the abrasives used in Comparative Examples 1 to 4 are shown in Table 1 below.

[0052] The preparation method is as follows: A resin composition is coated on one side of the substrate layer to a thickness of 30 μm, and then a semi-cured layer is formed by UV pre-curing. Using electrostatic sand planting method, with a controlled voltage of 80kV, sand was planted on the semi-hardened layer, and the sand planting coverage rate was 92%, resulting in a sand-planted layer. Then, a resin composition is coated a second time on the sand layer to a thickness of 5μm. The mixture is then placed in a tunnel oven, preheated at 80℃ for 3 minutes, and then deeply crosslinked at 150℃ for 10 minutes to obtain sandpaper.

[0053] Table 1. Source of abrasives used in Examples 1-14 and Comparative Examples 1-5

[0054] The sandpapers obtained in Examples 1-14 and Comparative Examples 1-5 were tested for wet grinding life, grinding efficiency, wet grinding life after wet heat aging, and grinding efficiency after wet heat aging. The test results are shown in Table 2 below.

[0055] The wet grinding life test was conducted according to ISO 6344 standard. Sandpaper was used to grind 304 stainless steel plate in a humid environment of 85%RH, and the time (h) when the abrasive shedding rate reached 10% was recorded. The test equipment and parameters were: Taber type wet grinding test machine, load 5kg, speed 60rpm.

[0056] The grinding efficiency was tested according to ISO 60315 standard, measuring the mass of aluminum alloy (6061) removed per unit time (g / min); test parameters: grinding pressure 2kg, linear speed 10m / min.

[0057] To test the wet grinding life and grinding efficiency after wet heat aging, the sandpaper is first subjected to wet heat aging before the wet grinding life and grinding efficiency are tested. The wet heat aging adopts (ASTM D3045), which places the sandpaper in a constant temperature and humidity chamber (85℃ / 85%RH) for 24 hours to simulate accelerated aging.

[0058] Comparative examples 3 and 4 in the test results show that the abrasives selected for the test were severely agglomerated during the preparation process. Only abrasives with the required particle size could be screened from the obtained material for preparation and testing. The actual screening pass rate was less than 20%.

[0059] Table 2. Detection results of Examples 1-14 and Comparative Examples 1-5

[0060] As shown in Table 2, compared with Comparative Examples 1 and 2, Example 1 of this application used the abrasive with a porous water-resistant interface layer prepared in Preparation Example 1, Comparative Example 1 used the initial, unmodified abrasive, and Comparative Example 2 used the abrasive modified with a hydrophobic silane coupling agent prepared in Preparation Example 2. In the test results, the wet grinding life and grinding efficiency of Example 1 were significantly better than those of Comparative Examples 1 and 2. Furthermore, after wet heat aging, the wet grinding life and grinding efficiency of Example 1 were even more significantly superior to those of Comparative Examples 1 and 2.

[0061] The reason is that the porous water-resistant interface layer on the surface of the abrasive in Preparation Example 1 has hierarchical pores. These hierarchical pores allow the bonded resin to penetrate and solidify to form a nano-anchoring structure. The mechanical locking force between the abrasive and the bonding layer is significantly improved compared to the planar interface bonding force of Comparative Examples 1 and 2, thereby enhancing the bonding strength between the abrasive and the bonding layer from a physical structure perspective. The porous water-resistant interface layer is composed of a zinc imidazole ester framework. The zinc imidazole ester contains nitrogen atoms with lone pairs of electrons, which can react with the epoxy groups of the epoxy resin to form covalent bonds. At the same time, the zinc nodes form coordination bonds with the hydroxyl or carboxyl groups in the resin, which improves the bonding strength between the abrasive and the adhesive layer from a chemical perspective. Compared to traditional methods that rely on physical adsorption and hydrogen bonding, the abrasive in this application significantly enhances its bonding force through the synergistic effect of mechanical interlocking of covalent and coordination bonds, and the strength of the bonding interface is significantly improved in terms of resistance to humid heat aging. In addition, the pores on the porous water-resistant interface layer are slightly larger than the dynamic diameter of water molecules, but its surface hydrophobicity means that water only needs to overcome a high energy barrier to wet and penetrate through a small contact angle. This prevents water from wetting the interface between the abrasive and the bonding layer, and can play a role in preventing water from softening the interface. The elastic modulus of zinc imidazole ester is based on the relationship between the abrasive and the resin, which can alleviate stress concentration caused by abrupt changes in modulus and reduce the possibility of abrasive shedding. Therefore, the sandpaper of this application solves the problems of abnormal abrasive detachment, reduced service life, and poor sanding effect caused by the softening of the interface between the abrasive and the bonding layer due to water through the synergistic effects of mechanical interlocking, chemical bonding, hydrophobic inhibition, and stress buffering between the abrasive and the bonding layer. This enables the sandpaper of this application to have sanding performance that is adaptable to humid environments, efficient, and durable.

[0062] In addition, this application investigated the preparation process for the formation of porous water-resistant interfaces, and further compared Examples 1-3 and Comparative Examples 3-4.

[0063] The abrasive used in Example 2 was derived from Preparation Example 3, in which water was used as the solvent for the reaction of zinc nitrate and 2-methylimidazole. The abrasive used in Example 3 was derived from Preparation Example 4, in which the rotation speed was faster during the reaction process to prevent abrasive sedimentation. The abrasive used in Comparative Example 3 was from Preparation Example 5. The rotation speed in Preparation Example 5 was lower than that in Preparation Example 1 during the reaction, and the abrasive showed obvious sedimentation. As the reaction proceeded, the abrasive in Preparation Example 5 showed obvious agglomeration and clumping after settling to the bottom, and was unusable. The abrasive used in Comparative Example 4 was from Preparation Example 6. In Preparation Example 6, the methanol solution of 2-methylimidazole was not added dropwise, but directly added to the methanol solution of zinc nitrate, and the mixture was stirred to carry out the reaction. The resulting abrasive showed obvious agglomeration and was unusable. The test results show that the wet grinding life, grinding efficiency, wet grinding life after damp heat aging, and grinding efficiency after damp heat aging of Example 1 are all better than those of Examples 2 and 3. Furthermore, considering that the abrasives used in Preparation Examples 5 and 6 exhibited agglomeration and particle size variation that could not meet the requirements for uniform particle size in sandpaper grinding, methanol was used as the solvent when preparing a porous water-resistant interface on the abrasive surface in this application. A methanol solution of 2-methylimidazole was added to a methanol solution of zinc nitrate by dropwise addition, and the mixture was stirred at an appropriate speed to avoid abrasive sedimentation and reduce the peeling of the formed porous water-resistant interface layer. As a result, the wet grinding life, grinding efficiency, and resistance to damp heat aging of the sandpaper obtained by this method are all superior.

[0064] Comparing Examples 1 and 4-7, the difference lies in the different molar ratios of zinc ions to 2-methylimidazole used in the preparation of the porous water-resistant interface layer. In Examples 4, 5, 1, 6, and 7, the molar ratio of zinc ions to 2-methylimidazole gradually increases. In the test results, the wet grinding life and grinding efficiency of Examples 5-6, as well as the wet grinding life and grinding efficiency after wet heat aging, are better than those of Examples 4 and 7. The wet grinding life and grinding efficiency of Example 1, as well as the wet grinding life and grinding efficiency after wet heat aging, are better than those of Examples 5-6. Therefore, in this application, a molar ratio of 1:4 of zinc ions to 2-methylimidazole is preferred when preparing the porous water-resistant interface layer on the abrasive surface.

[0065] Comparing Examples 1 and 8-11, it can be seen that the difference lies in the pH of the reaction environment when the abrasive is used to prepare the porous water-resistant interface layer. In Examples 8, 9, 1, and 10, the pH of the reaction environment gradually increases. In the test results, the wet grinding life and grinding efficiency of Examples 9-10, as well as the wet grinding life and grinding efficiency after wet heat aging, are better than those of Examples 8 and 11. The wet grinding life and grinding efficiency of Example 1, as well as the wet grinding life and grinding efficiency after wet heat aging, are better than those of Examples 9-10. Therefore, it is better to maintain the pH of the reaction environment at 7.5-8 when preparing the porous water-resistant interface layer on the abrasive surface in this application.

[0066] Comparing Examples 1 and 12-13, Examples 12-13, compared to Example 1, further optimized the abrasive based on the preparation example 1. Before preparing the porous water-resistant interface layer, the abrasive was modified with an aminosilane coupling agent. The introduction of amino groups on the surface makes the abrasive surface easier to protonate. The amino groups can enhance the adsorption of zinc ions by the abrasive, improve the nucleation density and uniformity during the subsequent growth of zinc imidazole ester, and thus improve its interfacial bonding strength.

[0067] Therefore, Examples 12-13 are superior to Example 1 in terms of wet grinding life and grinding efficiency, as well as wet grinding life and grinding efficiency after wet heat aging. Among the two, Example 12 is the best. Therefore, when modifying the surface of the abrasive with an aminosilane coupling agent in this application, γ-aminopropyltriethoxysilane is preferred.

[0068] Meanwhile, in Comparative Example 5, the abrasive of Comparative Example 5 was first surface modified with a non-aminosilane coupling agent, and then a porous water-resistant interface was prepared. The test results showed that its wet grinding life and grinding efficiency, as well as its wet grinding life and grinding efficiency after wet heat aging, were not better than those of Example 1, and even decreased compared to Example 1. This further verifies the effect of the abrasive surface modification with an aminosilane coupling agent in Examples 12-13 of this application, which introduces amino groups on the surface of the abrasive.

[0069] Comparing Examples 12 and 14, it can be seen that the wet grinding life and grinding efficiency of Example 14, as well as the wet grinding life and grinding efficiency after wet heat aging, are further improved compared to Example 12. Furthermore, the stirring rate during the reaction stage of the abrasive preparation process in Example 14 is lower than that in Example 1. This is because a certain amount of polyvinylpyrrolidone was added to the methanol solution of zinc nitrate to adjust the viscosity of the methanol solution of zinc nitrate, reducing the sedimentation rate of the abrasive. This allows for a lower stirring speed to meet the requirement of avoiding abrasive sedimentation. The reduced stirring speed can reduce the shedding of the porous water-resistant interface layer caused by abrasive particle collision, thereby improving the integrity and coverage of the porous water-resistant interface layer. This enhances the bonding strength and waterproof softening performance between the abrasive and the bonding layer, thus improving the sandpaper's grinding performance, grinding efficiency, and resistance to wet heat aging.

[0070] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of protection claimed by the present invention, they are protected by patent law.

Claims

1. A high-efficiency, durable, and water-resistant sandpaper suitable for humid environments, characterized in that: Includes a substrate layer, an adhesive layer, and an abrasive layer; The adhesive layer is located on one side of the substrate layer and is formed by curing a resin composition. The abrasive layer is formed by the distribution of abrasive particles, with one end of the abrasive particles embedded in the bonding layer; The abrasive surface has a porous, water-resistant interface layer formed by a zinc imidazole ester framework; The porous, water-resistant interface layer is obtained by reacting abrasives in a methanol solution of zinc nitrate and 2-methylimidazole to form a zinc imidazole ester framework.

2. The high-efficiency, durable, and water-resistant sandpaper suitable for humid environments according to claim 1, characterized in that, The preparation process of the porous water-resistant interface layer is as follows: Zinc nitrate is dissolved in methanol to obtain a methanol solution of zinc nitrate, and 2-methylimidazole is dissolved in methanol to obtain a methanol solution of 2-methylimidazole. The abrasive was added to a methanol solution of zinc nitrate and dispersed evenly. While stirring, a methanol solution of 2-methylimidazole was slowly added dropwise. The reaction was carried out at room temperature for 6 hours with a stirring speed of 50-100 rpm to prevent the abrasive from piling up and depositing. After the reaction was complete, the abrasive was washed with methanol and then vacuum dried at a temperature below 80°C to obtain an abrasive with a porous, water-resistant interface layer.

3. The high-efficiency, durable, and water-resistant sandpaper suitable for humid environments according to claim 2, characterized in that, During the preparation of the porous water-resistant interface layer, the molar ratio of zinc ions to 2-methylimidazole is 1:

4.

4. The high-efficiency, durable, and water-resistant sandpaper suitable for humid environments according to claim 2, characterized in that, Before preparing the porous water-resistant interface layer, the abrasive is first surface modified with an aminosilane coupling agent.

5. The high-efficiency, durable, and water-resistant sandpaper suitable for humid environments according to claim 4, characterized in that, The aminosilane coupling agent is γ-aminopropyltriethoxysilane.

6. The high-efficiency, durable, and water-resistant sandpaper suitable for humid environments according to claim 2, characterized in that, The pH was maintained at 7.5-8 during the reaction.

7. The high-efficiency, durable, and water-resistant sandpaper suitable for humid environments according to claim 2, characterized in that, The methanol solution of zinc nitrate also contains polyvinylpyrrolidone.

8. A method for preparing high-efficiency, durable, and water-resistant sandpaper suitable for humid environments, characterized in that, Includes the following steps: A resin curing agent is coated on one side of the substrate layer, and then pre-cured to form a semi-hardened layer; Abrasives are used to implant sand onto the semi-hardened layer to form a sand-implanted layer. A resin composition is coated a second time onto the sand layer, and then cured in stages to finally obtain sandpaper.

Images