Multifunctional composite abrasive paper and composite forming process thereof

Abstract

The invention relates to the field of abrasive tools, in particular to multifunctional composite abrasive paper and a composite forming process thereof. The multifunctional composite abrasive paper comprises a base material layer, an abrasive material layer, a functional coating and a dustproof layer which are sequentially compounded, the base material layer is a polyester fiber cloth or aramid fiber non-woven fabric base material subjected to plasma treatment and silane coupling agent treatment, and the abrasive material layer is formed through an electrostatic sand planting process. The functional coating comprises a cleaning agent, a polishing agent and an anti-rust agent, and the dustproof layer is an electrostatic spinning nanofiber membrane; through gradient abrasive material design, microcapsule step-by-step control and low-temperature curing processes, the technical effects of integrating multiple functions of abrasive paper self-cleaning, rust prevention and polishing, reducing the replacement frequency and improving the grinding efficiency are achieved.

Description

A multifunctional composite sandpaper and its composite molding process Technical Field

[0001] This invention relates to the field of abrasive tools, and in particular to a multifunctional composite sandpaper and its composite molding process. Background Technology

[0002] Sandpaper is a surface treatment tool made by firmly attaching abrasive particles to the surface of a flexible or semi-rigid substrate (such as paper, cloth, polyester film, or composite substrate) with an adhesive. Its core function is to utilize the cutting ability of the abrasive particles to grind, polish, and clean the surface of a workpiece through friction, thereby removing burrs, flash, oxide layers, old coatings, smoothing the surface, and achieving a specific roughness or gloss level. Sandpaper is an indispensable basic consumable in modern manufacturing, processing, repair and maintenance, and DIY fields. Depending on the substrate, abrasive type, grit size, abrasive application method (e.g., gravity abrasive, electrostatic abrasive), and binder, sandpaper products come in various forms, mainly including: By substrate: dry sandpaper (paper-based, cloth-based, film-based), water-resistant sandpaper (paper-based), non-woven abrasive discs, abrasive belts, abrasive rolls, abrasive discs, abrasive sleeves, shaped abrasive blocks, etc.; By grit size: coarse grit P24-P80, used for heavy cutting; medium grit P100-P180, used for rough grinding and leveling; fine grit P220-P600, used for fine grinding; ultrafine grit P800 and above, used for polishing and finishing; By application: metal sandpaper, woodworking sandpaper, automotive putty sandpaper, stainless steel sandpaper, dry sanding for painted surfaces, rust removal sandpaper, polishing sandpaper, etc. The performance of sandpaper directly determines processing efficiency, surface quality, and production costs.

[0003] Despite its widespread use, traditional sandpaper and its application processes still face a series of significant problems in practical applications: Limited functionality and cumbersome procedures: ① Most conventional sandpaper products only have a single, fixed grit size or abrasive type. When dealing with complex workpieces requiring multiple grinding passes, from coarse to medium, fine, and polishing, operators must frequently change sandpaper grits. This not only leads to process interruptions, reduced production efficiency, and increased operator workload, but also easily causes positioning errors due to sandpaper changes, affecting processing accuracy and surface consistency. ② Insufficient lifespan and durability: Especially when grinding hard materials such as metals, hardwoods, and composite materials, or performing heavy-duty grinding, abrasive particles are prone to premature passivation and detachment, and the substrate is easily worn or torn. Short sandpaper lifespan leads to frequent replacements, increasing material consumption costs and generating more waste. ③ The contradiction between sanding efficiency and surface quality: Coarse-grit sandpaper has high cutting efficiency but easily leaves deep scratches and a rough surface; fine-grit sandpaper can achieve a smooth surface but has low cutting efficiency. It is difficult for sandpaper of a single grit to remove material efficiently while ensuring a high final surface quality. ④ Environmental pressure: A large amount of discarded short-life sandpaper becomes one of the sources of solid waste, and its recycling and disposal are difficult, putting pressure on the environment.

[0004] In response to the aforementioned technologies, there is an urgent need in this field to develop a multifunctional composite sandpaper and its composite molding process to solve the technical problems of the limitation of existing sandpaper with a single grit size, extend its service life, reduce the number of replacements, improve grinding efficiency, and enhance its adaptability to complex workpieces and materials. Summary of the Invention

[0005] To address the limitations of existing sandpaper with a single grit size, extend its service life, reduce replacement frequency, improve grinding efficiency, and enhance its adaptability to complex workpieces and materials, this application provides a multifunctional composite sandpaper and its composite molding process.

[0006] In a first aspect, this application provides a multifunctional composite sandpaper, employing the following technical solution: A multifunctional composite sandpaper comprises the following structural layers sequentially laminated: a substrate layer, an abrasive layer, a functional coating, and a dustproof layer; wherein: the functional coating contains a cleaning agent, a polishing agent, and a rust inhibitor, and at least one functional agent is encapsulated within a heat-sensitive or pressure-sensitive microcapsule; the dustproof layer is an electrospun nanofiber membrane, and its air permeability is ≥1500 mL / cm² under a pressure difference of 100 Pa. 2 / s.

[0007] By adopting the above-mentioned scheme, microcapsule controlled-release technology triggers microcapsule rupture through frictional heat or pressure, releasing functional agents on demand, while simultaneously addressing storage stability and achieving a shelf life of >24 months; a single grinding process can simultaneously complete cutting, cleaning, polishing, and rust prevention, improving overall efficiency; the dustproof layer is a nano-level dustproof membrane with an air permeability ≥1500 mL / cm². 2 / s, while effectively protecting the functional coating.

[0008] Preferably, the substrate layer is a polyester fiber cloth or aramid nonwoven fabric substrate treated with plasma and silane coupling agent, with a thickness of 0.6-1.5 mm.

[0009] By adopting the above scheme, the dual composite treatment technology of ion treatment and silane coupling agent solves the core pain points of traditional sandpaper substrates, such as easy delamination and poor fatigue resistance. Plasma treatment can effectively remove organic impurities and generate free radical active sites, while silane coupling agent avoids secondary pollution at the interface and forms a dense Si-O-Si network structure.

[0010] Preferably, the abrasive layer is formed by an electrostatic sand-coating process, and the abrasive particles include: corundum with a particle size of P80, silicon carbide with a particle size of P180, and calcined alumina with a particle size of P600.

[0011] By adopting the above scheme, the design life and quality of gradient abrasives are improved. P80 coarse particles are used for rapid degreasing, P180 medium particles are used for fine finishing, and P600 fine particles are used for polishing. This shortens the grinding time and avoids the repeated operation of changing sandpaper immediately after coarse grinding.

[0012] Preferably, the functional coating comprises, by weight percentage: 20-30% microcapsules, 8-15% diatomaceous earth, and the balance being water-based polyurethane resin. The microcapsules include cleaning agent microcapsules, rust inhibitor microcapsules, and polishing agent microcapsules mixed in a mass ratio of (1-2):1:1.

[0013] Preferably, the microcapsules in the functional coating include: the cleaning agent microcapsules: the wall material is naphthalene sulfonic acid condensate, and the core is a nonionic surfactant and propylene glycol; the rust inhibitor microcapsules: the wall material is ethylene-vinyl acetate copolymer, and the core is a vapor phase rust inhibitor; the polishing agent microcapsules: the wall material is shellac, and the core is nano-cerium oxide; and the melting point range of the microcapsule wall material is 60-80℃.

[0014] Preferably, the core component of the rust inhibitor microcapsule is a vapor-phase rust inhibitor selected from at least one of cyclohexylamine carboxylate and benzoate.

[0015] Preferably, the nano-cerium oxide particles have a diameter of 40-60 nm.

[0016] By adopting the above solution, the cleaning agent instantly removes oil and debris; the cerium oxide polishing agent automatically refines the surface roughness; the rust inhibitor forms a molecular protective film on the metal surface, and the vapor phase rust inhibitor microcapsules: cyclohexylamine carboxylate sublimates to form a protective gas that penetrates into crevices and dead corners; rust prevention is achieved for 72 hours between processes, eliminating the need for the traditional step of applying rust-preventive oil; traditional functional coatings release their active ingredients upon application, with 90% of the active ingredients becoming ineffective during storage, while microcapsule encapsulation effectively extends the storage time of functional coatings and protects the three functional agents in separate areas.

[0017] Secondly, this application provides a composite molding process for multifunctional composite sandpaper, employing the following technical solution: S1 Substrate layer treatment: Plasma treatment of the substrate followed by coating with a silane coupling agent; S2 Abrasive layer preparation: An adhesive is coated on the surface of the substrate layer in step S1, and abrasive particles are implanted using an electrostatic sanding process; S3 Functional coating: Diatomaceous earth is added to water-based polyurethane resin, stirred and dispersed for 10 minutes, rust inhibitor microcapsules are added, mixed thoroughly, polishing agent microcapsules are added, mixed thoroughly, and then cleaning agent microcapsules are added. The mixture is stirred at 500 rpm for 3-5 minutes, and degassed under vacuum at -0.08 MPa for 8-10 minutes to obtain a functional coating liquid. The functional coating liquid is then coated onto the surface of the abrasive layer in step S2 using a slot coating process; S4 Dustproof layer lamination: A dustproof layer is then covered by a copolyamide hot melt adhesive dot matrix coating on the surface of the functional coating in step S3, with a dot matrix density of 35-45 dots / cm². 2 Hot pressing is performed at a temperature of 120-130℃, a pressure of 0.3-0.5 MPa, and a roller speed of 4.0-5.0 m / min. S5 curing: 48-53℃, wind speed of 0.4-0.8 m / s, for 20-30 minutes.

[0018] This composite sandpaper molding process solves the core problem of compatibility issues in multifunctional coatings through gradient abrasive design, step-by-step microcapsule control, and low-temperature curing. The substrate layer achieves high flexibility in a thin substrate and high strength in a thick substrate through dual composite treatment technology of ion treatment and silane coupling agent, providing a highly reliable substrate layer for composite sandpaper. The gradient abrasive and integrated design of the abrasive layer can significantly shorten grinding time and avoid the repetitive work of changing sandpaper after coarse grinding. The functional coating improves the activity retention rate of rust inhibitors, polishing agents, and cleaning agents through microcapsule technology, and diatomaceous earth ensures that the microcapsules are fully wetted in water-based polyurethane resin to prevent sedimentation. The low-temperature curing process, which cures at 50°C, does not trigger microcapsule melting and maintains microcapsule integrity.

[0019] Preferably, step S1, the substrate layer treatment, includes the following steps: surface activation treatment of polyester fiber cloth or aramid nonwoven fabric substrate using atmospheric pressure plasma, with a treatment power of 2.8-3.2 kW, an argon flow rate of 18-22 L / min, and the substrate distance from the electrode being 5-10 mm; within 30 s after plasma treatment, a silane coupling agent solution is roller-coated onto the substrate surface, and the coated substrate is pre-baked at 75-85℃ for 30-60 s, and then cured at 100-115℃ for 90-120 s to obtain the substrate layer.

[0020] By adopting the above scheme, plasma precision etching forms micro-nano pits, and silane coating within 30 seconds achieves in-situ condensation of -OH active free radicals, solving the bonding failure caused by free radical decay; 0.6mm aramid is as flexible as leather, and 1.5mm polyester is as strong as steel, achieving high flexibility in thin base and high strength in thick base, providing a highly reliable substrate layer for composite sandpaper.

[0021] Preferably, the silane coupling agent solution is prepared by adding 1.8-2.0 parts of KH-550 to 100 parts of an ethanol aqueous solution and adjusting the pH value to 4.5-5.0 with acetic acid; wherein the ethanol aqueous solution is prepared by mixing deionized water and ethanol at a mass ratio of 100:(4-5).

[0022] Preferably, in step S1, the silane coupling agent solution is roller-coated onto the substrate surface using an anilox roller coating process. The anilox roller mesh count is 240-260 mesh, and the wet coating amount is 4.5-5.5 g / m². 2 .

[0023] Preferably, in step S1, the thickness of the substrate layer is 0.6-1.5 mm, and the peel strength between the substrate layer and the abrasive layer is ≥32 N / cm.

[0024] Preferably, in step S1, when the substrate is aramid nonwoven fabric, the thickness of the treated substrate layer is 0.6-0.8 mm and the minimum bending radius is ≤5 mm; when the substrate is polyester fiber fabric, the thickness of the treated substrate layer is 1.2-1.5 mm and the tensile strength is ≥800 N / cm.

[0025] Preferably, in step S2, the abrasive layer is prepared by: coating the substrate layer surface in step S1 with an adhesive, the wet film thickness of which is 0.3-0.35 mm; sequentially implanting abrasive particles with a gradient particle size distribution using a segmented electrostatic sand-planting process; the bottom layer: implanting calcined alumina at a density of 50-60 particles / cm³ under a voltage of 65-75 kV. 2 Middle layer: Silicon carbide is implanted at a voltage of 75-85kV, with a density of 60-70 particles / cm³. 2Top layer: Corundum is implanted under 85-95kV voltage, with a density of 50-60 particles / cm²; the air pressure of the three-section abrasive fluidized bed is 0.05 MPa, and each section is pre-cured at 85-95℃ for 50-60s after sand implantation; the sand density of the abrasive layer is 160-190 particles / cm². 2 .

[0026] By adopting the above scheme and using gradient electric field sand-planting technology, the abrasive distribution accuracy, bonding strength, and wear resistance life are improved. The voltage increases with the density of the implanted abrasive particles, solving the problem of multi-size mixed distribution. Calcined alumina fills the bottom layer, silicon carbide transitions, and corundum protrudes to the surface, achieving an integrated grinding and polishing effect. The voltage gradient from 70kV to 90kV matches the exponential demand for adsorption force due to increased particle size. Segmented pre-curing effectively prevents interlayer abrasive mixing and avoids subsequent sand-planting damaging the cured layer. If the infrared pre-curing temperature is below 85℃, the resin will not gel, causing subsequent sand-planting to disturb the previous layer; if the temperature is above 95℃, the adhesive will cure prematurely, leading to abrasive adsorption failure. Infrared pre-curing at 85-95℃ for 50-60s yields the best performance.

[0027] Preferably, the adhesive is mixed with 4-6% by weight of nano-alumina in the epoxy phenolic resin.

[0028] Preferably, in step S3, the slit coating process has a coating die lip gap of 0.1-0.3 mm, a coating speed of 4-5 m / min, an inlet guide angle of ≥60°, and a flow channel surface roughness Ra≤0.1 μm.

[0029] Preferably, the cleaning agent microcapsules in step S3 are prepared from the following raw materials in parts by weight: 45-50 parts of naphthalenesulfonic acid condensate wall material are dissolved in 110-120 parts of deionized water at 80°C, and then the core material is added; after mixing, the mixture is emulsified to 2-5 μm at 10000 rpm, polymerized at 75°C and pH=3.5 for 120 min, and spray-dried at 180°C for inlet air and 80°C for outlet air to obtain cleaning agent microcapsules with a particle size of 30-35 μm and a melting point of 60-70°C; wherein, the core material is prepared by mixing 35-40 parts of nonionic surfactant, 4-5 parts of propylene glycol mixture, 1.3-1.8 parts of Tween 80 and 28-35 parts of deionized water.

[0030] Preferably, the rust inhibitor microcapsules in step S3 are prepared from the following raw materials in parts by weight: 38-43 parts of ethylene-vinyl acetate copolymer are dissolved in 400 parts of dichloromethane to obtain a wall material solution, then 55-65 parts of cyclohexylamine carboxylate core material, 3-6 parts of polyvinyl alcohol emulsifier, and 800 parts of deionized water are added, emulsified at 8000 rpm, and the solvent is evaporated at 40°C for 4 hours; dried in a fluidized bed at 50°C, to obtain rust inhibitor microcapsules with a particle size of 35-45 μm and a melting point of 60-70°C.

[0031] Preferably, the polishing agent microcapsules in step S3 are prepared from the following raw materials in parts by weight: 52-60 parts shellac are dissolved in 330 parts anhydrous ethanol to obtain a wall material solution; 40-50 parts nano-cerium oxide, 1.2-1.3 parts KH-560 and 10 parts anhydrous ethanol are mixed to form a core solution; the wall material solution and the core solution are mixed, and 300 parts of 10% ammonium sulfate solution are added dropwise at 40°C and pH=8.5 to coagulate; 0.5-0.6 parts of 25% glutaraldehyde aqueous solution are added, and the crosslinking reaction is carried out at 40°C for 60 min, pre-frozen at -40°C for 12 h, and sublimated at -50°C and 10 Pa to freeze dry, to obtain polishing agent microcapsules with a particle size of 15-25 μm and a melting point of 70-80°C; wherein, the acid value of shellac is 70-75.

[0032] In summary, this application has the following beneficial effects: 1. The multifunctional composite sandpaper prepared by this application through composite molding process achieves the technical effect of self-cleaning, rust prevention and polishing of sandpaper, reducing the number of replacements and improving sanding efficiency.

[0033] 2. The multifunctional composite sandpaper of this application utilizes a dual composite treatment technology of ion treatment and silane coupling agent in its substrate layer to achieve high flexibility in a thin substrate and high strength in a thick substrate, providing a highly reliable substrate layer for the composite sandpaper. The gradient abrasive and integrated design of the abrasive layer can significantly shorten grinding time and avoid the repetitive work of changing sandpaper after coarse grinding. The microcapsule controlled-release technology of the functional coating triggers microcapsule rupture through frictional heat or pressure, releasing functional agents as needed, while simultaneously solving storage stability and ensuring a shelf life of >24 months. The nano-level dustproof membrane of the dustproof layer has high air permeability, preventing the accumulation of frictional heat and effectively protecting the functional coating. The four-layer multifunctional composite sandpaper design enables the simultaneous completion of cutting, cleaning, polishing, and rust prevention processes in a single grinding operation, improving overall efficiency. Detailed Implementation

[0034] The technical solution of this application is further illustrated by specific embodiments below. These specific embodiments do not represent a limitation on the scope of protection of this application. Any non-essential modifications and adjustments made by others based on the concept of this application still fall within the scope of protection of this application.

[0035] Corundum: Zhengzhou Dajiang Wear-Resistant Products Co., Ltd., Grade A white corundum, particle size P80; Silicon carbide: Shandong Jinmeng New Material Co., Ltd., CAS: 409-21-2, particle size P180; Calcined alumina: Shenzhen Baoan District Fuhai Chuangbo Ceramic Raw Material Factory, 800 mesh; Nano alumina: Shanghai Pantian Powder Materials Co., Ltd., item number: PT- AlO-30nm; Waterborne polyurethane resin: Guangzhou Propylene Glycol Co., Ltd., Model: HG-7835, Item No.: 20240510002; Naphthalene sulfonic acid condensate (Alias: Sodium methylnaphthalene sulfonate formaldehyde condensate, abbreviation NSF): Shaoxing Zhezao Chemical Co., Ltd., CAS: 9084-06-4; Propylene glycol: Dongguan Delun New Materials Co., Ltd., CAS: 1629-06-8, Item No.: 5656; Ethylene-vinyl acetate copolymer: Taiwan Polymer Chemicals Co., Ltd., Grade UE639-04; Nano cerium oxide: Shanghai Yaotian New Materials Technology Co., Ltd., Item No.: Cerium oxide, 50nm; Diatomaceous earth: Lingshou Shuanglong Mining Co., Ltd., Model: gzt05, 100-200 mesh; Epoxy modified phenolic resin: Guangzhou Haihong Chemical Co., Ltd., Model: F44, Item No.: 20230511.

[0036] Unless otherwise specified, the experimental methods shown in the following examples are conventional methods. All reagents and materials shown are commercially available products.

[0037] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0038] Preparation Example

[0039] Preparation Example 1: Preparation of three types of microcapsules in functional coatings. Cleaning agent microcapsules: 48g of naphthalene sulfonic acid condensate wall material was dissolved in 115g of deionized water at 80℃, and then the core material was added; after mixing, it was emulsified at 10000rpm to 2-5μm, and polymerized at 75℃ and pH=3.5 for 120min. After spray drying, the inlet air temperature was 180℃ and the outlet air temperature was 80℃ to obtain cleaning agent microcapsules with a particle size of 30-35μm and a melting point of 60-70℃; wherein, the core material was prepared by mixing 38g of nonionic surfactant, 4g of propylene glycol mixture, 1.5g of Tween 80 and 32g of deionized water.

[0040] Rust inhibitor microcapsules: 40g of ethylene-vinyl acetate copolymer was dissolved in 400g of dichloromethane to obtain a wall material solution. Then, 60g of cyclohexylamine carboxylate core material, 5g of polyvinyl alcohol emulsifier, and 800g of deionizer were added. After emulsification at 8000rpm, the solvent was evaporated at 40℃ for 4h. After drying in a fluidized bed at 50℃, rust inhibitor microcapsules with a particle size of 35-45μm and a melting point of 60-70℃ were obtained.

[0041] Polishing agent microcapsules: 58g shellac was dissolved in 330g anhydrous ethanol to obtain a wall material solution. 45g nano-cerium oxide, 1.2g KH-560 and 10g anhydrous ethanol were mixed to form a core solution. The wall material solution and core solution were mixed, and 300g of 10% ammonium sulfate solution was added dropwise at 40℃ and pH=8.5 to coagulate. 0.5g of 25% glutaraldehyde aqueous solution was added, and the mixture was crosslinked at 40℃ for 60min, pre-frozen at -40℃ for 12h, and then sublimated and freeze-dried at -50℃ and 10Pa to obtain polishing agent microcapsules with a particle size of 15-25μm and a melting point of 70-80℃.

[0042] Preparation Example 2: Preparation of Three Microcapsules in Functional Coatings Cleaning Agent Microcapsules: 45g of naphthalenesulfonic acid condensate wall material was dissolved in 110g of deionized water at 80℃, and then the core material was added; after mixing, it was emulsified at 10000rpm to 2-5μm, polymerized at 75℃ and pH=3.5 for 120min, and spray-dried at 180℃ inlet and 80℃ outlet to obtain cleaning agent microcapsules with a particle size of 30-35μm and a melting point of 60-70℃; wherein, the core material was prepared by mixing 35g of nonionic surfactant, 4g of propylene glycol mixture, 1.3g of Tween 80 and 28g of deionized water.

[0043] Rust inhibitor microcapsules: 38g of ethylene-vinyl acetate copolymer was dissolved in 400g of dichloromethane to obtain a wall material solution. Then, 55g of cyclohexylamine carboxylate core material, 3g of polyvinyl alcohol emulsifier, and 800g of deionized water were added. After emulsification at 8000rpm, the solvent was evaporated at 40℃ for 4h. After drying in a fluidized bed at 50℃, rust inhibitor microcapsules with a particle size of 35-45μm and a melting point of 60-70℃ were obtained.

[0044] Polishing agent microcapsules: 52g shellac was dissolved in 330g anhydrous ethanol to obtain a wall material solution. 40g nano-cerium oxide, 1.2g KH-560 and 10g anhydrous ethanol were mixed to form a core solution. The wall material solution and core solution were mixed, and 300g of 10% ammonium sulfate solution was added dropwise at 40℃ and pH=8.5 to coagulate. 0.5g of 25% glutaraldehyde aqueous solution was added, and the mixture was crosslinked at 40℃ for 60min, pre-frozen at -40℃ for 12h, and then sublimated and freeze-dried at -50℃ and 10Pa to obtain polishing agent microcapsules with a particle size of 15-25μm and a melting point of 70-80℃.

[0045] Preparation Example 3: Preparation of Three Types of Microcapsules in Functional Coatings Cleaning Agent Microcapsules: 50g of naphthalenesulfonic acid condensate wall material was dissolved in 120g of deionized water at 80℃, and then the core material was added; after mixing, it was emulsified at 10000rpm to 2-5μm, polymerized at 75℃ and pH=3.5 for 120min, and spray-dried at 180℃ for inlet air and 80℃ for outlet air to obtain cleaning agent microcapsules with a particle size of 30-35μm and a melting point of 70-80℃; wherein, the core material was prepared by mixing 40g of nonionic surfactant, 5g of propylene glycol mixture, 1.8g of Tween 80 and 35g of deionized water.

[0046] Rust inhibitor microcapsules: 43g of ethylene-vinyl acetate copolymer was dissolved in 400g of dichloromethane to obtain a wall material solution. Then, 65g of cyclohexylamine carboxylate core material, 6g of polyvinyl alcohol emulsifier, and 800g of deionized water were added. After emulsification at 8000rpm, the solvent was evaporated at 40℃ for 4h. After drying in a fluidized bed at 50℃, rust inhibitor microcapsules with a particle size of 35-45μm and a melting point of 60-70℃ were obtained.

[0047] Polishing agent microcapsules: 60g of shellac was dissolved in 330g of anhydrous ethanol to obtain a wall material solution. 50g of nano-cerium oxide, 1.3g of KH-560, and 10g of anhydrous ethanol were mixed to form a core solution. The wall material solution and core solution were mixed, and 300g of 10% ammonium sulfate solution was added dropwise at 40℃ and pH=8.5 to coagulate. 0.6g of 25% glutaraldehyde aqueous solution was added, and the mixture was crosslinked at 40℃ for 60min, pre-frozen at -40℃ for 12h, and then sublimated and freeze-dried at -50℃ and 10Pa to obtain polishing agent microcapsules with a particle size of 15-25μm and a melting point of 70-80℃. Example

[0048] Example 1: A composite molding process for multifunctional composite sandpaper, using the following technical solution: S1 Substrate layer treatment: Atmospheric pressure plasma is used to perform surface activation treatment on the polyester fiber cloth substrate. The treatment power is 3.0kW, the argon flow rate is 20 L / min, and the substrate is 8 mm away from the electrode. Within 30 seconds after plasma treatment, a silane coupling agent solution is roller-coated onto the substrate surface. The anilox roller has a mesh count of 240 and a wet coating amount of 5 g / m². 2 After coating, the substrate is pre-baked at 80℃ for 50s and then cured at 110℃ for 100s to obtain the substrate layer; S2 Abrasive layer preparation: An adhesive is coated on the surface of the substrate layer in step S1, and the wet film thickness of the adhesive is 0.3mm; Abrasive particles with a gradient particle size distribution are sequentially implanted using a segmented electrostatic sand-planting process. The bottom layer: calcined alumina is implanted under a voltage of 70kV, with a density of 55 particles / cm³. 2 Middle layer: Silicon carbide is implanted at 80kV, with a density of 65 particles / cm³. 2Top layer: Corundum implanted under 90kV voltage, density 55 particles / cm²; the air pressure of the three-section abrasive fluidized bed is 0.05 MPa, and each section is pre-cured at 90℃ for 60s after sand implantation; the sand density of the abrasive layer is 175 particles / cm². 2 S3 Functional Coating: 1.2 kg of diatomaceous earth and 6.3 kg of water-based polyurethane resin were added and stirred for 10 min. The total amount of microcapsules added was 2.5 kg, including 0.625 kg of rust inhibitor microcapsules. After mixing, 0.625 kg of polishing agent microcapsules were added, and after mixing, 1.25 kg of cleaning agent microcapsules were added. The mixture was stirred at 500 rpm for 5 min and then degassed under vacuum at -0.08 MPa for 10 min to obtain the functional coating liquid. The functional coating liquid was coated onto the surface of the abrasive layer in step S2 using a slot coating process. The die lip gap was 0.2 mm, and the coating speed was 4 m / min. The inlet guide angle was ≥60°, and the surface roughness of the flow channel Ra was ≤0.1 μm. S4 Dustproof Layer Lamination: After applying a copolyamide hot melt adhesive dot matrix coating to the surface of the functional coating in step S3, a dustproof layer was covered with it. The dot matrix density was 40 dots / cm. 2 Hot pressing was performed at 120℃, 0.4 MPa, and 4.0 m / min; S5 curing was carried out at 50℃ and 0.6 m / s for 25 min.

[0049] The rust inhibitor microcapsules, polishing agent microcapsules, and cleaning agent microcapsules in the functional coating were prepared by Preparation Example 1; the silane coupling agent solution was prepared by adding 4g of anhydrous ethanol to 100g of deionized water and mixing, then adding 2.0g of KH-550 to 100g of ethanol aqueous solution and adjusting the pH to 5.0 with acetic acid; the adhesive was prepared by adding 5g of nano-alumina to 100g of epoxy phenolic resin and mixing.

[0050] Example 2: A composite molding process for multifunctional composite sandpaper, employing the following technical solution: S1 Substrate layer treatment: Atmospheric pressure plasma is used to perform surface activation treatment on the aramid nonwoven fabric substrate. The treatment power is 2.8 kW, the argon flow rate is 18 L / min, and the substrate is 5 mm away from the electrode. Within 30 seconds after plasma treatment, a silane coupling agent solution is roller-coated onto the substrate surface. The anilox roller has a mesh count of 240 and a wet coating amount of 4.5 g / m². 2 After coating, the substrate is pre-baked at 75℃ for 30 seconds and then cured at 100℃ for 120 seconds to obtain the substrate layer; S2 Abrasive layer preparation: An adhesive is coated on the surface of the substrate layer in step S1, and the wet film thickness of the adhesive is 0.35 mm; Abrasive particles with a gradient particle size distribution are sequentially implanted using a segmented electrostatic sand-planting process. The bottom layer: calcined alumina is implanted under 75 kV voltage, with a density of 50 particles / cm²; the middle layer: silicon carbide is implanted under 75 kV voltage, with a density of 60 particles / cm²; the top layer: corundum is implanted under 85 kV voltage, with a density of 50 particles / cm².2 The air pressure of the three-section abrasive fluidized bed is 0.05 MPa. After sand planting in each section, it is pre-cured at 85℃ for 50 seconds using infrared technology. The sand planting density of the abrasive layer is 160 particles / cm³. 2 S3 Functional Coating: Add 0.8 kg of diatomaceous earth to 7.2 kg of water-based polyurethane resin, stir and disperse for 10 min. The total amount of microcapsules added is 2 kg, including 0.50 kg of rust inhibitor microcapsules. After mixing, add 0.50 kg of polishing agent microcapsules, mix well, and then add 1.0 kg of cleaning agent microcapsules. Stir at 500 rpm for 3 min, and degas under vacuum at -0.08 MPa for 8 min to obtain the functional coating liquid. Apply the functional coating liquid to the surface of the abrasive layer in step S2 using a slot coating process. The die lip gap is 0.1 mm, and the coating speed is 4 m / min. The inlet guide angle is ≥60°, and the surface roughness of the flow channel Ra is ≤0.1 μm. S4 Dustproof Layer Lamination: After applying a copolyamide hot melt adhesive dot matrix coating to the surface of the functional coating in step S3, cover it with a dustproof layer. The dot matrix density is 35 dots / cm. 2 Hot pressing composite was performed at 120℃, 0.3MPa, and 4.0m / min; S5 curing: 48℃, 0.4m / s for 20min.

[0051] The rust inhibitor microcapsules, polishing agent microcapsules, and cleaning agent microcapsules in the functional coating were prepared by Preparation Example 2; the silane coupling agent solution was prepared by adding 4g of anhydrous ethanol to 100g of deionized water and mixing, then adding 1.8g of KH-550 to 100g of ethanol aqueous solution and adjusting the pH to 4.5 with acetic acid; the adhesive was prepared by adding 4g of nano-alumina to 100g of epoxy phenolic resin and mixing.

[0052] Example 3: A composite molding process for multifunctional composite sandpaper, employing the following technical solution: S1 Substrate layer treatment: Atmospheric pressure plasma is used to perform surface activation treatment on the polyester fiber cloth substrate. The treatment power is 3.2 kW, the argon flow rate is 22 L / min, and the substrate is 10 mm away from the electrode. Within 30 seconds after plasma treatment, a silane coupling agent solution is roller-coated onto the substrate surface. The anilox roller has a mesh count of 260 mesh, and the wet coating amount is 5.5 g / m². 2 After coating, the substrate is pre-baked at 85℃ for 60s and then cured at 115℃ for 90s to obtain the substrate layer; S2 Abrasive layer preparation: An adhesive is coated on the surface of the substrate layer in step S1, and the wet film thickness of the adhesive is 0.35mm; Abrasive particles with a gradient particle size distribution are sequentially implanted using a segmented electrostatic sand-planting process. The bottom layer: calcined alumina is implanted under a voltage of 75kV, with a density of 60 particles / cm³. 2 Middle layer: Silicon carbide is implanted at 85kV, with a density of 70 particles / cm²; Top layer: Corundum is implanted at 95kV, with a density of 60 particles / cm². 2The air pressure of the three-section abrasive fluidized bed is 0.05 MPa. After sand planting in each section, it is pre-cured at 95℃ for 60 seconds using infrared technology. The sand planting density of the abrasive layer is 190 particles / cm³. 2 S3 Functional Coating: Add 1.5 kg of diatomaceous earth and 5.5 kg of water-based polyurethane resin, stir and disperse for 10 min. The total amount of microcapsules added is 3 kg, including 0.75 kg of rust inhibitor microcapsules. After mixing, add 0.75 kg of polishing agent microcapsules, mix well, and then add 1.5 kg of cleaning agent microcapsules. Stir at 500 rpm for 5 min, and degas under vacuum at -0.08 MPa for 8-10 min to obtain the functional coating liquid. Apply the functional coating liquid to the surface of the abrasive layer in step S2 using a slot coating process. The die lip gap is 0.3 mm, and the coating speed is 5 m / min. The inlet guide angle is ≥60°, and the surface roughness of the flow channel Ra is ≤0.1 μm. S4 Dustproof Layer Lamination: After applying a copolyamide hot melt adhesive dot matrix coating to the surface of the functional coating in step S3, cover it with a dustproof layer. The dot matrix density is 45 dots / cm², the temperature is 130℃, the pressure is 0.5 MPa, and the roller speed is 5.0. Hot pressing composite is performed at a speed of m / min; S5 curing: 53℃, wind speed 0.8 m / s, curing for 30 min.

[0053] The rust inhibitor microcapsules, polishing agent microcapsules, and cleaning agent microcapsules in the functional coating were prepared by Preparation Example 3; the silane coupling agent solution was prepared by adding 5g of anhydrous ethanol to 100g of deionized water and mixing, then adding 2.0g of KH-550 to 100g of ethanol aqueous solution and adjusting the pH to 5.0 with acetic acid; the adhesive was prepared by adding 6g of nano-alumina to 100g of epoxy phenolic resin.

[0054] Example 4: A composite molding process for multifunctional composite sandpaper, employing the following technical solution: S1 Substrate layer treatment: Atmospheric pressure plasma is used to perform surface activation treatment on the aramid nonwoven fabric substrate. The treatment power is 2.8 kW, the argon flow rate is 22 L / min, and the substrate is 5 mm away from the electrode. Within 30 seconds after plasma treatment, a silane coupling agent solution is roller-coated onto the substrate surface. The anilox roller has a mesh count of 260 mesh, and the wet coating amount is 4.5 g / m². 2 After coating, the substrate is pre-baked at 85℃ for 30 seconds and then cured at 115℃ for 90 seconds to obtain the substrate layer; S2 Abrasive layer preparation: An adhesive is coated on the surface of the substrate layer in step S1, and the wet film thickness of the adhesive is 0.3 mm; Abrasive particles with a gradient particle size distribution are sequentially implanted using a segmented electrostatic sand-planting process. The bottom layer: calcined alumina is implanted under a voltage of 75 kV, with a density of 60 particles / cm³. 2 Middle layer: Silicon carbide is implanted at 75kV, with a density of 60 particles / cm³. 2 Top layer: Corundum implanted under 95kV voltage, density 60 particles / cm³ 2The air pressure of the three-section abrasive fluidized bed is 0.05 MPa. After sand planting in each section, it is pre-cured at 85℃ for 60 seconds using infrared technology. The sand planting density of the abrasive layer is 180 particles / cm³. 2 S3 Functional Coating: 1 kg of diatomaceous earth is added to 6.5 kg of water-based polyurethane resin and stirred for 10 min. The total amount of microcapsules added is 2.5 kg, including 0.833 kg of rust inhibitor microcapsules. After mixing, 0.833 kg of polishing agent microcapsules are added, and after mixing, 0.833 kg of cleaning agent microcapsules are added. The mixture is stirred at 500 rpm for 5 min and then degassed under vacuum at -0.08 MPa for 10 min to obtain the functional coating liquid. The functional coating liquid is coated onto the surface of the abrasive layer in step S2 using a slot coating process. The coating die lip gap is 0.3 mm, and the coating speed is 5 m / min. The inlet guide angle is ≥60°, and the surface roughness of the flow channel Ra is ≤0.1 μm. S4 Dustproof Layer Lamination: After applying a copolyamide hot melt adhesive dot matrix coating to the surface of the functional coating in step S3, a dustproof layer is covered with a dot matrix density of 35 dots / cm. 2 Hot pressing was performed at 130℃, 0.3MPa, and 5.0 m / min; S5 curing: 48℃ and 0.8 m / s for 20 min.

[0055] The rust inhibitor microcapsules, polishing agent microcapsules, and cleaning agent microcapsules in the functional coating were prepared by Preparation Example 1; the silane coupling agent solution was prepared by adding 4g of anhydrous ethanol to 100g of deionized water and mixing, then adding 1.8g of KH-550 to 100g of ethanol aqueous solution and adjusting the pH to 5.0 with acetic acid; the adhesive was prepared by adding 5g of nano-alumina to 100g of epoxy phenolic resin and mixing.

[0056] Example 5: A composite molding process for multifunctional composite sandpaper, employing the following technical solution: S1 Substrate layer treatment: Atmospheric pressure plasma is used to perform surface activation treatment on the polyester fiber cloth substrate. The treatment power is 3.2 kW, the argon flow rate is 18 L / min, and the substrate is 10 mm away from the electrode. Within 30 seconds after plasma treatment, a silane coupling agent solution is roller-coated onto the substrate surface. The anilox roller has a mesh count of 240 and a wet coating amount of 5.5 g / m². 2 After coating, the substrate is pre-baked at 80℃ for 30s and then cured at 115℃ for 90s to obtain the substrate layer; S2 Abrasive layer preparation: An adhesive is coated on the surface of the substrate layer in step S1, and the wet film thickness of the adhesive is 0.35mm; Abrasive particles with a gradient particle size distribution are sequentially implanted using a segmented electrostatic sand-planting process. The bottom layer: calcined alumina is implanted under a voltage of 65kV, with a density of 50 particles / cm³. 2 Middle layer: Silicon carbide is implanted at 85kV, with a density of 70 particles / cm³. 2Top layer: Corundum is implanted under 85kV voltage, with a density of 50 particles / cm²; the air pressure of the three-section abrasive fluidized bed is 0.05 MPa, and each section is pre-cured at 85℃ for 50s after sand implantation; the sand density of the abrasive layer is 170 particles / cm². 2 S3 Functional Coating: 1.3 kg of diatomaceous earth and 5.7 kg of water-based polyurethane resin were added and stirred for 10 min. The total amount of microcapsules added was 3 kg, including 1.0 kg of rust inhibitor microcapsules. After mixing, 1.0 kg of polishing agent microcapsules were added, followed by 1.0 kg of cleaning agent microcapsules. The mixture was stirred at 500 rpm for 3 min and then degassed under vacuum at -0.08 MPa for 10 min to obtain the functional coating liquid. The functional coating liquid was then coated onto the surface of the abrasive layer in step S2 using a slot coating process. The die lip gap was 0.1 mm, and the coating speed was 5 m / min. The inlet guide angle was ≥60°, and the surface roughness of the flow channel Ra was ≤0.1 μm. S4 Dustproof Layer Lamination: After applying a copolyamide hot melt adhesive dot matrix coating to the surface of the functional coating in step S3, a dustproof layer was applied. The dot matrix density was 45 dots / cm. 2 Hot pressing was performed at 120℃, 0.5 MPa, and 4.0 m / min; S5 curing was carried out at 53℃ and 0.4 m / s for 25 min.

[0057] The rust inhibitor microcapsules, polishing agent microcapsules, and cleaning agent microcapsules in the functional coating were prepared by Preparation Example 2; the silane coupling agent solution was prepared by adding 5g of anhydrous ethanol to 100g of deionized water and mixing, then adding 1.9g of KH-550 to 100g of ethanol aqueous solution and adjusting the pH to 4.5 with acetic acid; the adhesive was prepared by adding 5g of nano-alumina to 100g of epoxy phenolic resin and mixing.

[0058] Comparative Example

[0059] Comparative Example 1 is the same as Example 1, except that the substrate layer treatment in step S1 is different. The plasma treatment is omitted, and the silane coupling agent is directly coated.

[0060] Comparative Example 2 is the same as Example 1, except that the substrate layer in step S1 is not subjected to plasma treatment and coated with silane coupling agent.

[0061] Comparative Example 3 is the same as Example 1, except that the electrostatic sand planting process in step S2 is different. The three layers of sand are all planted under a voltage of 70kV, and the density is 60-70 particles / cm². Calcined alumina, silicon carbide and corundum abrasive are planted in sequence.

[0062] Comparative Example 4 is the same as Example 1, except that the proportion of raw materials for the functional coating in step S3 is different. 1 kg of microcapsules and 1.8 kg of diatomaceous earth are added to the functional coating, with the remainder being water-based polyurethane resin. Among the microcapsules, the cleaning agent microcapsules, rust inhibitor microcapsules, and polishing agent microcapsules are in a mass ratio of 1:2:1.

[0063] Comparative Example 5 is the same as Example 1, except that the hot pressing process conditions in step S4 are different, with a lattice density of 25 dots / cm² and a temperature of 135°C.

[0064] Comparative Example 6 is the same as Example 1, except that the curing conditions in step S5 are different: 75°C, wind speed 0.5m / s, curing for 200min.

[0065] Performance testing

[0066] The multifunctional composite sandpapers prepared in Examples 1-5 and Comparative Examples 1-6 were subjected to functional tests. Grinding ratio (G ratio): the workpiece volume / grinding wheel wear volume was tested according to JIS R6253-2022; abrasive shedding rate: the proportion of abrasive particles detached after wear was tested according to GB / T9258.2; wear amount: the grinding wheel mass loss after 1000 revolutions was tested using a Taber abrasion tester; service life: the time until the grinding efficiency decreased by 50% was simulated under actual working conditions.

[0067] Test conditions: Workpiece material: 304 stainless steel plate (100×100×5mm); Grinding parameters: pressure 15N, linear speed 25m / s, time 10min / cycle; each group was repeated 5 times and the average value was taken.

[0068] The performance test results are shown in Table 1.

[0069] Table 1. Performance Test Results of Samples Prepared in Examples 1-5 and Comparative Examples 1-6 G Ratio Sand Shedding Rate (%) Wear Amount (mg) Service Life (min) Example 1 6 2.7 4.2 15 2 5 8 Example 2 6 1.3 4.3 15 9 5 3 Example 3 6 1.8 4.2 16 7 5 6 Example 4 6 2.2 4.6 16 3 5 7 Example 5 6 1.9 4.4 15 3 5 2 Comparative Example 1 4 5.3 18.6 28 7 2 8 2 8 7 2 8 2 8 7 2 8 2 8 7 8 2 8 13 19 Comparative Example 3 5 3.1 7.9 21 8 4 1 Comparative Example 4 4 ​​8.7 11.3 26 4 3 5 Comparative Example 5 5 7.2 8.5 19 5 4 7 Comparative Example 6 5 1.6 6.3 23 8 3 9 surface

[0070] As shown in Table 1, the multifunctional composite sandpaper prepared in Examples 1-5 underwent functional tests, with a grinding ratio ranging from 61.3 to 62.7, a sand shedding rate of 4.2% to 4.6%, a wear amount ranging from 152 to 167 mg, and a service life of 52 to 58 minutes. The multifunctional composite sandpaper prepared by the composite molding process achieves the technical effects of self-cleaning, rust prevention, and polishing in one, reducing the number of replacements and improving grinding efficiency.

[0071] In Comparative Example 1, the plasma treatment was omitted from the substrate layer treatment, and silane coupling agent was directly coated, resulting in a detachment rate of 18.6%. This indicates that plasma activation created active sites, and the silane coupling agent effectively enhanced chemical bonding. Without plasma activation, the interfacial bonding was weaker. In Comparative Example 2, the substrate layer was not subjected to plasma treatment and was coated with silane coupling agent, resulting in a detachment rate of 16.5% and a wear amount of 413 mg. The failure of the substrate-resin interface accelerated abrasive detachment, leading to a decrease in the effective cutting depth of the abrasive grains. In Comparative Example 3, the electrostatic sand-planting process differed. All three layers of sand-planting were performed at 70 kV, with a density of 60-70 grains / cm², a grinding ratio of 53.1, a wear amount of 218 mg, and a service life of 41 min. This indicates that a uniform 70 kV resulted in insufficient abrasive embedding depth, and the chaotic abrasive distribution led to localized stress concentration. The middle silicon carbide layer failed to form an effective support layer due to insufficient voltage, accelerating wear. In Comparative Example 4, the coating material ratio was different, resulting in a grinding ratio of 48.7, a wear amount of 264 mg, and a service life reduced to 35 min. This was due to insufficient total microcapsule volume and a low detergent ratio, leading to insufficient lubrication and wear debris adhesion. Excessive diatomaceous earth, accounting for 36% of the coating, weakened resin continuity and reduced matrix wear resistance. In Comparative Example 5, the hot-pressing process conditions were different, resulting in a wear amount of 195 mg and a service life of 47 mg. The high temperature of 135℃ caused excessive penetration of the hot melt adhesive, which enhanced short-term bonding strength but increased brittleness, resulting in 25 points / cm. 2 Insufficient lattice density led to localized debonding in the later stages, accelerating the lifespan decay. In Comparative Example 6, with different curing conditions, the sand shedding rate was 6.3%. Due to the excessively high resin crosslinking density caused by curing at 75℃, the impact toughness decreased, and the tendency for brittle fracture increased. The G ratio decreased to 51.6, and the service life was 39 minutes. Due to the excessively high elastic modulus of the resin, the micro-fractured abrasive particles failed to detach in time to replace the cutting edge.

[0072] The above test results show that the multifunctional composite sandpaper prepared by this application through composite molding process achieves high flexibility in a thin substrate and high strength in a thick substrate through dual composite treatment technology of ion treatment and silane coupling agent, providing a highly reliable substrate layer for the composite sandpaper. The gradient abrasive and integrated design of the abrasive layer can significantly shorten the grinding time and avoid the repetitive work of changing sandpaper after rough grinding. The microcapsule controlled release technology of the functional coating triggers the microcapsule rupture through frictional heat or pressure, releasing the functional agent as needed, while solving storage stability and ensuring a shelf life of >24 months. The nano-level dustproof membrane of the dustproof layer has high air permeability, avoids the accumulation of frictional heat, and effectively protects the functional coating. The four-layer multifunctional composite sandpaper design enables the simultaneous completion of cutting, cleaning, polishing, and rust prevention processes in a single grinding operation, improving overall efficiency.

[0073] This specific embodiment is merely an explanation of the present invention and is not intended to limit the 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 the present invention, they are protected by patent law.

Claims

1. A multifunctional composite sandpaper, characterized in that, The structure comprises the following layers in sequence: a substrate layer, an abrasive layer, a functional coating, and a dustproof layer; wherein: the functional coating contains a cleaning agent, a polishing agent, and a rust inhibitor, and at least one functional agent is encapsulated in a heat-sensitive or pressure-sensitive microcapsule; the dustproof layer is an electrospun nanofiber membrane with an air permeability ≥1500 mL / cm² under a pressure difference of 100 Pa. 2 / s.

2. The multifunctional composite sandpaper according to claim 1, characterized in that, The abrasive layer is formed by an electrostatic sand-coating process, and its abrasive particles include: corundum with a particle size of P80, silicon carbide with a particle size of P180, and calcined alumina with a particle size of P600.

3. The multifunctional composite sandpaper according to claim 1, characterized in that, The functional coating comprises, by weight percentage: 20-30% microcapsules, 8-15% diatomaceous earth; the balance being water-based polyurethane resin. The microcapsules include cleaning agent microcapsules, rust inhibitor microcapsules, and polishing agent microcapsules mixed in a mass ratio of (1-2):1:

1.

4. The multifunctional composite sandpaper according to claim 3, characterized in that, The cleaning agent microcapsules have a wall material of naphthalene sulfonic acid condensate and a core of nonionic surfactant and propylene glycol; the rust inhibitor microcapsules have a wall material of ethylene-vinyl acetate copolymer and a core of vapor phase rust inhibitor; the polishing agent microcapsules have a wall material of shellac and a core of nano-cerium oxide; and the melting point range of the microcapsule wall material is 60-80℃.

5. A composite molding process for multifunctional composite sandpaper as described in any one of claims 1-4, characterized in that, The following technical solution is adopted: S1 Substrate layer treatment: The substrate is plasma treated and coated with a silane coupling agent; S2 Abrasive layer preparation: An adhesive is coated on the surface of the substrate layer in step S1, and abrasive particles are implanted through an electrostatic sand-planting process; S3 Functional coating: Diatomaceous earth is added to water-based polyurethane resin, stirred and dispersed for 10 min, rust inhibitor microcapsules are added, mixed well, polishing agent microcapsules are added, mixed well, and then cleaning agent microcapsules are added. The mixture is stirred at 500 rpm for 3-5 min, and degassed under vacuum at -0.08 MPa for 8-10 min to obtain a functional coating liquid. The functional coating liquid is coated onto the surface of the abrasive layer in step S2 using a slot coating process; S4 Dustproof layer lamination: A dustproof layer is covered on the surface of the functional coating in step S3 after a copolyamide hot melt adhesive is applied in a dot matrix pattern. The dot matrix density is 35-45 dots / cm², the temperature is 120-130℃, the pressure is 0.3-0.5 MPa, and the roller speed is 4.0-5.

0. Hot pressing composite is performed at a speed of m / min; S5 curing: 48-53℃, wind speed 0.4-0.8 m / s, curing for 20-30 min.

6. The composite molding process of the multifunctional composite sandpaper according to claim 5, characterized in that, The substrate layer treatment in step S1 includes the following steps: surface activation treatment of polyester fiber cloth or aramid nonwoven fabric substrate is performed using atmospheric pressure plasma, with a treatment power of 2.8-3.2 kW, an argon flow rate of 18-22 L / min, and the substrate distance from the electrode is 5-10 mm; within 30 s after plasma treatment, a silane coupling agent solution is roller-coated onto the substrate surface, and the coated substrate is pre-baked at 75-85℃ for 30-60 s and then cured at 100-115℃ for 90-120 s to obtain the substrate layer.

7. The composite molding process of the multifunctional composite sandpaper according to claim 5, characterized in that, The abrasive layer preparation in step S2: an adhesive is coated on the surface of the substrate layer in step S1, and the wet film thickness of the adhesive is 0.3-0.35 mm; abrasive particles with a gradient particle size distribution are sequentially implanted using a segmented electrostatic sand planting process. The bottom layer: calcined alumina is implanted under a voltage of 65-75 kV, with a density of 50-60 particles / cm². Middle layer: Silicon carbide is implanted under a voltage of 75-85kV, with a density of 60-70 particles / cm²; Top layer: Corundum is implanted under 85-95kV voltage, with a density of 50-60 particles / cm²; the air pressure of the three-section abrasive fluidized bed is 0.05 MPa, and each section is pre-cured at 85-95℃ for 50-60s after sand implantation; the sand density of the abrasive layer is 160-190 particles / cm².

8. The composite molding process of the multifunctional composite sandpaper according to claim 5, characterized in that, The cleaning agent microcapsules in step S3 are prepared from the following raw materials in parts by weight: 45-50 parts of naphthalenesulfonic acid condensate wall material are dissolved in 110-120 parts of deionized water at 80°C, and then the core material is added; after mixing, the mixture is emulsified to 2-5 μm at 10000 rpm, polymerized at 75°C and pH=3.5 for 120 min, and spray-dried at 180°C for inlet air and 80°C for outlet air to obtain cleaning agent microcapsules with a particle size of 30-35 μm and a melting point of 60-70°C; wherein, the core material is prepared by mixing 35-40 parts of nonionic surfactant, 4-5 parts of propylene glycol mixture, 1.3-1.8 parts of Tween 80 and 28-35 parts of deionized water.

9. The composite molding process of the multifunctional composite sandpaper according to claim 5, characterized in that: The rust inhibitor microcapsules in step S3 are prepared from the following raw materials in parts by weight: 38-43 parts of ethylene-vinyl acetate copolymer are dissolved in 400 parts of dichloromethane to obtain a wall material solution, and then 55-65 parts of cyclohexylamine carboxylate core material, 3-6 parts of polyvinyl alcohol emulsifier and 800 parts of deionized water are added. After emulsification at 8000 rpm, the solvent is evaporated at 40°C for 4 hours. After being dried in a fluidized bed at 50°C, rust inhibitor microcapsules with a particle size of 35-45μm and a melting point of 60-70°C were obtained.

10. The composite molding process of the multifunctional composite sandpaper according to claim 5, characterized in that: The polishing agent microcapsules in step S3 are prepared from the following raw materials in parts by weight: 52-60 parts shellac are dissolved in 330 parts anhydrous ethanol to obtain a wall material solution; 40-50 parts nano-cerium oxide, 1.2-1.3 parts KH-560 and 10 parts anhydrous ethanol are mixed to form a core solution; the wall material solution and the core solution are mixed, and 300 parts of 10% ammonium sulfate solution are added dropwise at 40℃ and pH=8.5 to coagulate; 0.5-0.6 parts of 25% glutaraldehyde aqueous solution are added, and the crosslinking reaction is carried out at 40℃ for 60 min, pre-frozen at -40℃ for 12 h, and sublimated at -50℃ and 10 Pa to freeze dry, to obtain polishing agent microcapsules with a particle size of 15-25 μm and a melting point of 70-80℃; wherein, the acid value of shellac is 70-75.