Sisal hemp polishing wheel sizing glue and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, and discloses sisal hemp polishing wheel sizing glue and a preparation method thereof.The sisal hemp polishing wheel sizing glue is formed by compounding vinyl acetate-acrylic emulsion, silica sol, ethylene-vinyl acetate copolymer emulsion and a thickening agent according to a specific formula, the vinyl acetate-acrylic emulsion is prepared from deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, a functional monomer, a compound emulsifier and a redox initiation system through a specific pre-emulsification-step dropwise adding process. According to the invention, a functional monomer is introduced to participate in copolymerization, and chemical bridging of a polymer and sisal fibers is constructed; a Si-O-Si inorganic network is formed by compounding silica sol, and the Si-O-Si inorganic network and an organic polymer chain generate strong hydrogen-bond interaction; by adding the VAE emulsion, the flexibility of an adhesive film and the wettability to plant fibers are improved, and the three components cooperate to form a stable interpenetrating network structure, so that the technical problems that the traditional sizing adhesive is poor in temperature resistance, insufficient in wear resistance and difficult to give consideration to both environmental friendliness and performance are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesives, in particular to a sisal polishing wheel setting glue and a preparation method thereof. BACKGROUND

[0002] Sisal polishing wheel is a polishing tool made of natural sisal fiber as the main raw material, through carding, laying, impregnating, molding and curing. It is widely used in the surface finishing of materials such as metal, wood and stone. The setting glue is a key material that gives sisal wheel shape, structural strength and durability, and its performance directly determines the service life, polishing accuracy and working efficiency of the polishing wheel. At present, sisal polishing wheel setting mainly relies on the following several types of adhesive systems: Phenolic resin: has excellent heat resistance and rigidity, but has obvious defects: a) the curing temperature is usually as high as 150℃ or above, with high energy consumption; b) the cured glue layer is brittle, and micro-cracks are easily produced under high-speed polishing impact, leading to fiber shedding; c) free formaldehyde may be released during production and use, with great environmental pressure; Epoxy resin: high bonding strength, but high cost. Solvent-based epoxy resin releases a large amount of volatile organic compounds (VOC) during curing, which does not meet the green manufacturing trend; while water-based epoxy resin is often insufficient in water resistance and high temperature and humidity resistance; Ordinary emulsion type adhesive (such as vinyl acetate homopolymer emulsion, i.e. white latex, VAE emulsion): environmentally friendly and non-toxic, easy to operate, but its glass transition temperature (Tg) is low, and it has poor heat resistance. In the high temperature environment generated by high-speed polishing (local temperature can reach above 120℃), the glue film is easy to soften and stick, leading to sisal fiber flying or shedding, which not only shortens the service life of the wheel body, but also pollutes the workpiece surface and causes blackening phenomenon; in addition, the hardness and wear resistance of such adhesives are usually insufficient, and they are difficult to withstand long-term wear and tear.

[0003] The main defects of existing sisal polishing wheel setting glue technology are as follows: contradiction between temperature resistance and environmental protection: high-performance phenolic and epoxy resins often come with high energy consumption or VOC problems, while environmentally friendly water-based emulsion does not meet the temperature resistance standard; single mechanical property: high-hardness resins have poor toughness, and tough emulsions have low hardness, making it difficult to meet the comprehensive mechanical requirements of polishing wheels for hardness without brittleness and toughness without stickiness; Weak interface bonding with plant fibers: most synthetic adhesives have limited chemical affinity with polar sisal fibers (rich in hydroxyl groups), mainly relying on physical anchoring, and the interface is easily damaged by water vapor, heat and other factors, leading to delamination; poor process adaptability: the viscosity curve and curing speed of existing adhesives do not match well with the impregnation and molding process of sisal fibers, affecting production efficiency and product uniformity.

[0004] Therefore, it is an urgent need to develop a sizing adhesive which can meet the requirements of high temperature resistance (≥120℃), high wear resistance, high strength, environmental protection, solvent-free and excellent interface bonding with sisal fiber, so as to improve the quality of sisal polishing wheel and promote the technical upgrading of the industry. SUMMARY In view of the above deficiencies of the prior art, the purpose of the present application is to provide a sisal polishing wheel sizing adhesive and a preparation method thereof, aiming to solve the technical problems of insufficient temperature resistance, poor wear resistance, poor environmental protection and weak interface bonding with sisal fiber of the existing sisal polishing wheel sizing adhesive.

[0005] The technical solution of the present application is as follows: A sisal polishing wheel sizing adhesive, wherein the components include, by mass fraction: 100 parts of vinyl-acrylic emulsion, 5-20 parts of silica sol, 10-20 parts of ethylene-vinyl acetate copolymer emulsion, and 0.5-2 parts of thickening agent; the raw materials of the vinyl-acrylic emulsion include: deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, functional monomer, anionic emulsifier, non-ionic emulsifier, oxidizing agent, and reducing agent.

[0006] The sisal polishing wheel sizing adhesive, wherein the raw materials of the vinyl-acrylic emulsion include, by mass fraction: 100 parts of deionized water; 50-70 parts of vinyl acetate; 1-6 parts of butyl acrylate; 10-20 parts of methyl methacrylate; 1-3 parts of acrylic acid; 1-10 parts of functional monomer; 0.5-2 parts of anionic emulsifier; 0.1-2 parts of non-ionic emulsifier; 0.1-0.2 parts of oxidizing agent; and 0.1-0.2 parts of reducing agent.

[0007] The sisal polishing wheel sizing adhesive, wherein the anionic emulsifier is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, disodium fatty alcohol polyoxyethylene ether sulfosuccinate, and sodium dodecyl diphenyl ether disulfate.

[0008] The sisal polishing wheel sizing adhesive, wherein the non-ionic emulsifier is one or both of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether.

[0009] The sisal polishing wheel sizing adhesive, wherein the functional monomer is one or more of silane coupling agent, hydroxypropyl acrylate, and N-hydroxymethyl acrylamide.

[0010] The sisal polishing wheel sizing adhesive, wherein the silane coupling agent is gamma-methacryloxypropyl trimethoxysilane.

[0011] The sisal polishing wheel sizing adhesive, wherein the oxidizing agent is one or more of sodium persulfate, ammonium persulfate, and potassium persulfate; and the reducing agent is a mixture of one or both of formaldehyde sodium bisulfite and sodium bisulfite.

[0012] The sizing glue of the sisal polishing wheel, wherein the particle size of the silica sol is 10-30 nm, and the solid content is 20-40%; the vinyl acetate content of the ethylene-vinyl acetate copolymer emulsion is 65-75%, and the solid content is 45-55%.

[0013] The sizing glue of the sisal polishing wheel, wherein the thickening agent is a polyacrylic alkali-swellable thickening agent or a polyurethane associated thickening agent.

[0014] A preparation method of the sizing glue of the sisal polishing wheel, comprising the steps of: Preparation of the vinyl-acrylic emulsion: Pre-emulsification: 60-80% of the total mass of deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, functional monomer, 60-80% of the total mass of anionic emulsifier and non-ionic emulsifier are added to the pre-emulsification kettle at room temperature and pressure, and stirred at a speed of 800-1500 rpm for 20-40 minutes to obtain a uniform and stable pre-emulsified liquid; Seed polymerization: the remaining deionized water and the remaining anionic emulsifier are added to the reaction kettle, heated to 78-82℃, then 5-15% of the total mass of the pre-emulsified liquid is added as seed liquid, then 40-60% of the total mass of the oxidizing agent and 40-60% of the total mass of the reducing agent are added, and the reaction is carried out at 78-82℃ for 20-40 minutes; Drop polymerization: the reaction temperature is maintained at 75-80℃, while the remaining pre-emulsified liquid is added to the reaction kettle, and the remaining oxidizing agent and reducing agent are added synchronously, and the drop time is controlled for 240-300 minutes; Post-treatment: after the drop is completed, the temperature is maintained at 75-80℃ for 40-60 minutes, then cooled to 45-55℃, and discharged to obtain the vinyl-acrylic emulsion; Compound of the sizing glue: the vinyl-acrylic emulsion, silica sol, ethylene-vinyl acetate copolymer emulsion and thickening agent are mixed uniformly under stirring according to the proportion, and the sizing glue of the sisal polishing wheel is obtained.

[0015] Beneficial effects: the sisal polishing wheel sizing glue provided by the application realizes the following significant technical progress through the above-mentioned ingenious formula design and preparation process, excellent high-temperature resistance: the glass transition temperature (Tg) can reach more than 45 DEG C, and the long-term use temperature is more than 130 DEG C, which is much higher than that of ordinary VAE or white latex (about 90 DEG C), effectively solving the problem of softening of the polishing wheel glue layer and fiber shedding under high-speed high-temperature operation; excellent wear resistance and long service life: the wear amount of the composite glue layer is as low as 0.03 g or less, and the service life of the polishing wheel is greatly improved from the industry average of 45 hours to more than 80 hours; super high bonding strength and interface stability: the tensile shear strength reaches more than 8.5 MPa, and the strength retention rate is high (>98%) after normal temperature storage or wet heat aging, which is due to the dual action of chemical bond bridge of silane coupling agent and physical interlocking of silica sol; excellent environmental protection: the whole system uses deionized water as the dispersion medium, without formaldehyde and organic solvent volatilization, in line with the most stringent environmental protection regulations; good process adaptability: viscosity can be adjusted, the sisal fiber is quickly infiltrated and deeply penetrated, suitable for existing sizing, roller coating, spraying and other various sizing processes, with low curing temperature requirement (100-120 DEG C), energy saving and consumption reduction; good comprehensive polishing effect: the sisal wheel has high surface finish of the polished workpiece, and no blackening pollution phenomenon occurs. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The preparation method flow chart of the sisal polishing wheel sizing glue provided by the application.

[0017] Figure 2 The polishing wear degree comparison chart of the sisal polishing wheels prepared by the sizing glue in example 1 and comparative example 1, wherein the left white is the state of the corresponding sisal polishing wheel after polishing in example 1, without blackening, good temperature resistance; and the right is the state of the corresponding sisal polishing wheel after polishing in comparative example 1, with blackening, poor temperature resistance, and large wear. DETAILED DESCRIPTION

[0018] The application provides a sisal polishing wheel sizing glue, a preparation method and application thereof, in order to make the purpose, technical scheme and effect of the application more clear and definite, the application is further described in detail below. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0019] The application provides a sisal polishing wheel sizing glue, which comprises, by mass percentage, 100 parts of a vinyl-acrylic emulsion, 5-20 parts of silica sol, 10-20 parts of an ethylene-vinyl acetate copolymer emulsion, and 0.5-2 parts of a thickening agent; raw materials of the vinyl-acrylic emulsion include deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, a functional monomer, an anionic emulsifier, a non-ionic emulsifier, an oxidizing agent, and a reducing agent.

[0020] The sizing glue system of the sisal buff provided by the embodiment is not simply physically blended, but achieves multi-level synergy of organic phase and inorganic phase, rigid chain segment and flexible chain segment, chemical bonding and physical entanglement through molecular design. The vinyl acetate propylene emulsion is used as the basic bonding resin and continuous phase of the system, and provides the main film-forming property and bonding force. The silica sol is used as the inorganic reinforcing phase and temperature-resistant modifier, and is uniformly dispersed in the polymer matrix. The ethylene-vinyl acetate copolymer emulsion is used as the flexible modifier and infiltration promoter. The thickening agent is used for adjusting the rheological property of the system to meet the requirements of the impregnation process.

[0021] Specifically, the silica sol is a dispersion of nano-sized SiO2 particles in deionized water, has a huge specific surface area and abundant surface silicon hydroxyl groups (Si-OH), and has the following effects when applied in the sizing glue of the sisal buff: As a temperature-resistant skeleton: during the curing process, a dense hydrogen bond network is formed between the silica sol particles and between the particles and the polar groups (such as -COOH and -OH) on the polymer chains; when heated, this inorganic hydrogen bond network is more stable than the organic molecular chain, and can effectively inhibit the thermal motion of the polymer chain, thereby greatly improving the heat distortion temperature and high-temperature strength retention rate of the adhesive; Wear-resistant reinforcement: the high-hardness nano-SiO2 particles are uniformly dispersed in the relatively soft polymer matrix, play a hard filling and bearing role, and significantly improve the surface hardness and friction resistance of the adhesive film; Interface strengthening and penetration: the nano-sized silica sol particles can penetrate into the micropores and gaps (average pore size of sisal fiber is 10-20 μm) on the surface of the sisal fiber, the Si-OH on the surface of the particles forms strong hydrogen bonds with the -OH on the fiber, and mechanical interlocking is achieved through capillary action, greatly enhancing the physical bonding between the adhesive and the fiber; Catalytic crosslinking: the acidic Si-OH on the surface of the silica sol can catalyze the condensation reaction between the carboxyl group and the methoxy group of the silane coupling agent to some extent, and promote the formation of the crosslinking network.

[0022] The amount of silica sol used in the embodiment is 5-20 parts, too little, the reinforcing effect is not obvious; too much, the brittleness of the adhesive layer may increase due to particle agglomeration, and the viscosity rises sharply, affecting the process. As an example, the particle size of the silica sol is 10-30 nm, and the solid content is 20-40%, but it is not limited thereto.

[0023] In the embodiment, the VAE emulsion is a copolymer of vinyl acetate and ethylene, the vinyl acetate content of the ethylene-vinyl acetate copolymer emulsion is 65-75%, and the solid content is 45-55%. The introduction of the ethylene segment makes it have a lower film-forming temperature, better flexibility and water resistance, and has the following effects when applied in the sizing glue of the sisal buff: Toughening and stress dispersion: VAE film has excellent flexibility and elasticity, which can form island structure or interpenetrating network with harder acetoxy-silica sol composite system, absorb and disperse impact energy and shear stress generated during polishing process, prevent crack propagation, and improve the fatigue life of the adhesive layer; Improved wetting and spreading: VAE emulsion has excellent wettability and permeability on the surface of porous and rough plant fibers, can quickly fill the gaps between fibers, ensure full contact between adhesive and fibers, and lay a foundation for subsequent chemical bonding and physical anchoring; Low temperature performance: improve the flexibility of the adhesive in low temperature environment to prevent brittle cracking.

[0024] The VAE emulsion provided by the embodiment has good compatibility with the acetoxy emulsion, and when the two are blended into a film, the polymer chains are intertwined, and at the same time, the acetate groups on the VAE chain segments, the carboxyl groups on the acetoxy chain segments, and the silicon hydroxyl groups of the silica sol can form extensive hydrogen bonds, building a three-dimensional interpenetrating network that is both rigid and flexible, and organic and inorganic interwoven. This network structure is the core of the sisal polishing wheel sizing adhesive that simultaneously achieves high hardness, high toughness, and high heat resistance.

[0025] In the embodiment, the thickening agent is used to precisely control the viscosity of the sizing adhesive (usually the target is 5000-15000 mPa·s @ 25℃). The appropriate viscosity ensures that the sisal fiber bundle can fully and uniformly absorb the adhesive solution during sizing, neither lacking adhesive to cause lack of sizing, nor having too much adhesive to cause dripping, waste, and pollution. As an example, the thickening agent is a polyacrylic alkali-swellable thickening agent or a polyurethane associative thickening agent, but is not limited thereto.

[0026] In some embodiments, the raw materials of the acetoxy emulsion include, by mass fraction: deionized water 100 parts; vinyl acetate 50-70 parts; butyl acrylate 1-6 parts; methyl methacrylate 10-20 parts; acrylic acid 1-3 parts; functional monomer 1-10 parts; anionic emulsifier 0.5-2 parts; nonionic emulsifier 0.1-2 parts; oxidizing agent 0.1-0.2 parts; reducing agent 0.1-0.2 parts.

[0027] Pure polyvinyl acetate (PVAc) emulsion (white latex) has low cost and good adhesion, but poor water resistance, low Tg (about 28℃), and poor creep resistance. By introducing acrylate monomers for copolymerization, the performance can be significantly improved. In the embodiment, vinyl acetate (VAc), butyl acrylate (BA), methyl methacrylate (MMA), acrylic acid (AA), and functional monomers are selected for multi-component copolymerization.

[0028] Specifically, vinyl acetate (50-70 parts) as the main monomer in the VAc-Pu emulsion of the present embodiment, provides basic adhesion performance and cost advantage, its content determines the flexibility and cost of the polymer, too low content will increase the cost and reduce the tackiness, too high content will result in insufficient heat resistance; Butyl acrylate (1-6 parts) as a soft monomer, its homopolymer Tg is -54℃, a small amount of introduction can internally plasticize, improve the flexibility and impact resistance of the film, prevent the glue layer from being too hard and brittle, but excessive amount will significantly reduce the hardness, heat resistance and wear resistance of the glue layer; methyl methacrylate (10-20 parts) as a hard monomer, its homopolymer Tg is 105℃, its core role has three: a) greatly improve the heat resistance: copolymerization with VAc can effectively improve the Tg of the copolymer; b) significantly improve the moisture resistance: VAc homopolymer has high moisture absorption rate, the hydrophobic methyl side chain of MMA can effectively block the intrusion of water molecules into the polymer chain, reducing the equilibrium water absorption rate of the film to less than 5% from about 40% of pure PVAc; c) improve the surface hardness and gloss: conducive to obtaining a bright surface of the workpiece after polishing; Acrylic acid (1-3 parts) as a functional monomer, its carboxyl group (-COOH) plays an important role: a) provides cross-linking points, which can react with the surface hydroxyl groups of the subsequently added silica sol, functional monomer functional groups, etc.; b) improves the stability of the emulsion (through steric hindrance and electrostatic repulsion); c) enhances the hydrogen bonding with polar substrates (such as sisal fibers); Functional monomer (1-10 parts), the functional monomer is one or more of silane coupling agent, hydroxypropyl acrylate and N-hydroxymethyl acrylamide. Preferably, the silane coupling agent containing double bond (such as γ-methacryloyloxypropyl trimethoxysilane), its role is as a molecular bridge: one end of the vinyl group participates in emulsion copolymerization and becomes part of the polymer chain; the other end of the methoxy group (-OCH3) is hydrolyzed into silanol (-Si-OH) during the curing process, which can either condense to form a Si-O-Si network or react with the hydroxyl groups (-OH) on the surface of the sisal fibers to form a firm Si-O-C covalent bond, which is the key to achieving high-strength interfacial chemical bonding; Composite emulsifier system (anion + non-ion): using an anionic emulsifier (such as sodium dodecyl sulfate, providing electrostatic stabilization) and a non-ionic emulsifier (such as OP-10, providing steric hindrance stabilization) to compound, can maintain the stability of the emulsion polymerization process and the final product in a wide range of pH, temperature and electrolyte concentration, especially conducive to the addition of subsequent silica sol (usually alkaline). As an example, the anionic emulsifier is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, fatty alcohol polyoxyethylene ether sulfosuccinic acid monoester disodium, and sodium dodecyl diphenyl ether disulfonate, but not limited to; the non-ionic emulsifier is one or both of alkyl phenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether, but not limited to; Redox initiation system: free radicals can be generated at relatively low temperature (75-80℃), realizing mild and uniform polymerization, avoiding explosive polymerization and monomer volatilization caused by high temperature, and being conducive to the formation of polymers with uniform molecular weight distribution; as an example, the oxidizing agent is one or more of sodium persulfate, ammonium persulfate and potassium persulfate; the reducing agent is a mixture of one or both of formaldehyde sodium hydrosulfite and sodium bisulfite, but is not limited thereto.

[0029] In some embodiments, a preparation method of the sisal polishing wheel setting glue as described in the application is also provided, as shown in Figure 1 The preparation method comprises the following steps: Preparation of the vinyl acetate propylene emulsion: S10, pre-emulsification: 60-80% of the total mass of deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, functional monomer, 60-80% of the total mass of anionic emulsifier and non-ionic emulsifier are added into a pre-emulsification kettle, stirred at a speed of 800-1500 rpm at normal temperature and pressure for 20-40 minutes to obtain a uniform and stable pre-emulsified liquid; S20, seed polymerization: the remaining deionized water and the remaining anionic emulsifier are added into a reaction kettle, heated to 78-82℃, then 5-15% of the total mass of the pre-emulsified liquid is added as a seed liquid, followed by adding 40-60% of the total mass of the oxidizing agent and 40-60% of the total mass of the reducing agent, and reacting at 78-82℃ for 20-40 minutes; S30, drop polymerization: the reaction temperature is maintained at 75-80℃, while the remaining pre-emulsified liquid is added dropwise into the reaction kettle, and the remaining oxidizing agent and reducing agent are added dropwise at the same time, and the dropwise time is controlled to be 240-300 minutes; S40, post-treatment: after the dropwise addition is completed, the temperature is maintained at 75-80℃ for 40-60 minutes, then cooled to 45-55℃, and the product is discharged to obtain the vinyl acetate propylene emulsion; S50, compounding of the setting glue: the vinyl acetate propylene emulsion, silica sol, ethylene-vinyl acetate copolymer emulsion and thickening agent are mixed uniformly under stirring according to the proportion to obtain the sisal polishing wheel setting glue.

[0030] Specifically, the preparation of the sisal polishing wheel sizing glue of the embodiment is divided into two steps: firstly, the synthesis of functionalized vinyl acetate-acrylate emulsion, and then the compounding of components. The preparation of the vinyl acetate-acrylate emulsion adopts a pre-emulsification + seed polymerization + semi-continuous dropping process. The advantages of the process are as follows: pre-emulsification: all monomers, emulsifiers and deionized water are pre-mixed and emulsified to form monomer droplets, so that the emulsion is small and uniform, ensuring the uniformity of the subsequent polymerization reaction, which is conducive to obtaining a polymer with a narrow molecular weight distribution and stable performance; seed polymerization: a small amount of pre-emulsified liquid is first polymerized to form a latex particle seed, which helps to control the nucleation process of the latex particle and obtain a latex with uniform particle size; semi-continuous dropping: the remaining pre-emulsified liquid is slowly dropped synchronously with the initiator, so that the monomer concentration in the reaction system is always maintained at a low level, which effectively inhibits the chain termination reaction between free radicals and is conducive to the generation of high molecular weight polymers, and can better control the polymerization heat to prevent explosive polymerization, which is the key to safe and stable implementation of industrial production. The compounding of components: the silica sol, VAE emulsion and thickening agent are added to the vinyl acetate-acrylate emulsion under low temperature conditions of <55℃. The low temperature can avoid the accelerated gelation of the silica sol due to high temperature, and also prevent unnecessary side reactions of residual monomers or initiators during the compounding process.

[0031] The sisal polishing wheel sizing glue provided by the application realizes the following significant technical progress through the above ingenious formula design and preparation process: excellent high-temperature resistance: the glass transition temperature (Tg) can reach more than 45℃, and the long-term use temperature is more than 130℃, which is much higher than that of ordinary VAE or white latex (about 90℃), effectively solving the problem of softening of the polishing wheel glue layer and fiber shedding under high-speed and high-temperature operation; excellent wear resistance and long service life: the wear amount of the composite glue layer is as low as less than 0.03g, and the service life of the polishing wheel is greatly improved from the industry average of 45 hours to more than 80 hours; ultra-high bonding strength and interface stability: the tensile shear strength reaches more than 8.5MPa, and the strength retention rate is high (>98%) after normal temperature storage or wet heat aging, which is due to the dual action of the chemical bond bridge of the silane coupling agent and the physical interlocking of the silica sol; excellent environmental protection: the entire system uses deionized water as the dispersion medium, without formaldehyde and organic solvent volatilization, meeting the most stringent environmental protection regulations; good process adaptability: the viscosity can be adjusted, the infiltration speed of the sisal fiber is fast, the penetration is deep, and it is suitable for various sizing processes such as existing impregnation, roller coating and spraying, with low curing temperature requirement (100-120℃), energy saving and consumption reduction; good comprehensive polishing effect: the sisal wheel polishing workpiece surface has high smoothness and no black pollution phenomenon.

[0032] The application will be further described below in conjunction with the embodiments. However, the following embodiments are only used to illustrate the content of the application, and are not limiting, so any change within the meaning and scope equivalent to the claims of the application should be considered as included in the scope of the claims.

[0033] Example 1 A sisal polishing wheel setting adhesive, the formulation of which, by weight, comprises: 100 parts of vinyl acetate-acrylic emulsion, 10 parts of silica sol (30% solid content, 20nm particle size), 15 parts of ethylene-vinyl acetate copolymer emulsion (70% vinyl acetate content, 50% solid content), and 1 part of thickener (ASE-60); wherein, the vinyl acetate-acrylic emulsion, by weight, comprises: 100 parts deionized water; 60 parts vinyl acetate (VAc); 3 parts butyl acrylate (BA); 15 parts methyl methacrylate (MMA); 2 parts acrylic acid (AA); 2 parts γ-methacryloyloxypropyltrimethoxysilane (KH-570); 1 part anionic emulsifier sodium dodecyl sulfate (SDS); 0.5 parts nonionic emulsifier alkylphenol polyoxyethylene ether (OP-10); 0.15 parts oxidizing agent sodium persulfate (NaPS); 0.15 parts reducing agent sodium bisulfite (NaHSO3).

[0034] Its preparation method includes the following steps: Preparation of acrylic emulsion: a. Pre-emulsification: Add 80 parts of deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, functional monomer, 0.8 parts of SDS and OP-10 to a pre-emulsification tank according to the formula, and stir at 25℃ and 1200 rpm for 30 minutes to obtain a milky white and uniform pre-emulsion A; b. Seed polymerization: Add 20 parts of deionized water and 0.2 parts of SDS to a four-necked reactor equipped with a stirrer, condenser, thermometer and dropping device. Turn on the stirrer and heat to 80°C. Add 10% of the total mass of pre-emulsion A, and then simultaneously add 50% of NaPS (dissolved in 5 parts of water) and 50% of NaHSO3 (dissolved in 5 parts of water). Maintain the reaction at 80°C for 30 minutes. The system will show blue light, indicating that seed latex particles have formed. c. Droplet polymerization: Adjust the reaction temperature to 78℃, and start to drop the remaining 90% of pre-emulsion A, as well as the remaining 50% NaPS aqueous solution and 50% NaHSO3 aqueous solution simultaneously. Control the dropping rate so that the total dropping time is about 270 minutes, and maintain the temperature at 78±1℃ during the dropping process. d. Post-processing: After the addition is complete, continue to maintain the temperature at 78℃ for 50 minutes. Then, cool the mixture with cooling water to 50℃, filter the material, and obtain functionalized vinyl acetate-acrylic emulsion B with a solid content of approximately 45%. Preparation of sizing adhesive: 100 parts of the vinyl acetate-acrylate emulsion B was placed in a stirring kettle, and 10 parts of silica sol and 15 parts of VAE emulsion were slowly added successively under stirring at 300 rpm. After the addition was completed, the stirring speed was increased to 600 rpm, and the mixture was stirred for 20 minutes to make it uniform. Finally, 1 part of thickening agent ASE-60 pre-diluted with an appropriate amount of water was slowly added under continuous stirring, the viscosity of the system was adjusted to about 10,000 mPa·s (25°C), and a sisal polishing wheel sizing adhesive C1 was obtained.

[0035] Example 2 A sisal polishing wheel sizing adhesive, compared with Example 1, the difference lies in that the amount of VAc is adjusted to 70 parts, and the amount of MMA is adjusted to 10 parts, to investigate the influence of the reduction of the proportion of hard monomers, and the rest of the ingredients and preparation process are the same as Example 1, and a sisal polishing wheel sizing adhesive C2 is prepared.

[0036] Example 3 A sisal polishing wheel sizing adhesive, compared with Example 1, the difference lies in that only the amount of silica sol is increased to 20 parts, to investigate the influence of the increase of the content of inorganic reinforcing phase, and the rest of the ingredients and preparation process are the same as Example 1, and a sisal polishing wheel sizing adhesive C3 is prepared.

[0037] Comparative Example 1 (commercially available milky white glue type I (RF601)) A commercially available polyvinyl acetate emulsion (solid content about 45%, Tg about 28°C) is used as a sizing adhesive, marked as D1, which does not contain MMA, functional monomer, silica sol, VAE and other modified ingredients, representing the most basic prior art.

[0038] Comparative Example 2 (without silane coupling agent KH-570) A sisal polishing wheel sizing adhesive, compared with Example 1, the difference lies in that no KH-570 functional monomer is added during the preparation of the vinyl acetate-acrylate emulsion, and a sizing adhesive D2 is prepared.

[0039] Comparative Example 3 (without silica sol) A sisal polishing wheel sizing adhesive, compared with Example 1, the difference lies in that no silica sol is added during the compounding of the sizing adhesive, and a sizing adhesive D3 is prepared.

[0040] Comparative Example 4 (without VAE emulsion) A sisal polishing wheel sizing adhesive, compared with Example 1, the difference lies in that no VAE emulsion is added during the compounding of the sizing adhesive, and a sizing adhesive D4 is prepared.

[0041] Comparative Example 5 (MMA amount is too low) A Manila polishing wheel setting glue, compared with the formula composition of Example 1, the difference is that the amount of MMA is changed from 15 parts to 2 parts, and the reduced 13 parts of mass is made up with the same amount of VAc (i.e. VAc is changed to 73 parts), and the setting glue D5 is prepared.

[0042] Comparative Example 6 (simple physical mixing of silica sol and vinyl acetate-acrylate emulsion) The purpose of this comparative example is to verify the importance of the synergy between the in-situ polymerization of the functional monomer and the post-added silica sol. The specific method is as follows: first, prepare the vinyl acetate-acrylate emulsion according to the formula and process of Comparative Example 2 (without KH-570); then, in the compounding stage, not only add silica sol, VAE and thickening agent, but also add an additional 2% of KH-570 (directly added, not involved in polymerization) based on the total mass of the emulsion, and stir and mix uniformly to prepare setting glue D6. The final content of each component in this formula is exactly the same as that of Example 1, but KH-570 does not participate in copolymerization and is only physically mixed.

[0043] The setting glue prepared in Examples 1-3 and Comparative Examples 1-6 is tested for film performance and simulated Manila wheel performance, wherein the film performance: each setting glue is cast into a film, dried at room temperature for 7 days, and then cured in an oven at 100°C for 2 hours to obtain a film with a thickness of about 0.5mm.

[0044] Wear amount: according to GB / T 1768-2006 standard, tested by Taber abrasion tester (CS-10 grinding wheel, 1000g load, 1000 revolutions), and the mass loss is calculated.

[0045] Application performance (simulated Manila wheel): prepare samples, immerse the same specification Manila fiber felt in each setting glue, control the same amount of glue (dry glue content accounts for 30% of the mass of the fiber), take out and mold into standard circular disc-shaped samples at 100°C, and then post-cure at 120°C for 2 hours.

[0046] Tensile shear strength: two pieces of samples are bonded with the corresponding setting glue, and after curing, the tensile shear strength is tested according to GB / T 7124-2008 standard.

[0047] Temperature resistance: the cured Manila wheel sample is placed in a 130°C oven for 24 hours, taken out and cooled, the surface state (whether sticky or powdery) is observed, and the residual tensile shear strength is tested to calculate the strength retention rate.

[0048] Actual polishing life: install the standard Manila polishing wheel made of each setting glue on a fixed polisher, polish 304 stainless steel plate at a constant pressure and speed, record the time until the diameter of the polishing wheel is worn out by more than 15% or serious flying silk and blackened workpiece appears, as the service life.

[0049] The performance test results are shown in Table 1.

[0050] Table 1 Performance test results

[0051] The performance test data of Table 1 strongly proves the remarkable effect of the technical solution of the present application (Examples 1-3), which realizes all-round significant improvement in core indicators such as high-temperature resistance, bonding strength, wear resistance and service life, compared with all the comparative examples. Comparative Example 1 (commercially available ordinary white latex), as a representative of traditional technology, has the lowest level in all performances. In contrast, the product of the present application increases the tensile-shear strength from 5.0 MPa to 8.6-8.9 MPa (more than 70% increase), increases the strength retention rate after 130℃ heat aging from 58% to 97-99%, greatly extends the polishing wheel service life from 30 hours to 78-85 hours (more than 160% increase), and reduces the film abrasion amount by about 65-75%, which marks that the present application successfully breaks through the performance bottleneck of traditional water-based adhesives in high-end industrial applications. The above data also show that the present application does not rely on the enhancement of a single component, but through the precise matching of the vinyl-acetate-proplyene emulsion matrix, silica sol, VAE emulsion and functional monomer and the combination of process, produces a synergistic effect. The absence of any key component (such as Comparative Examples 2-4) or improper ratio (such as Comparative Example 5), or the change of key process (such as Comparative Example 6), will lead to significant decline in comprehensive performance to different degrees, which inversely proves the necessity and innovation of the complete technical solution of the present application. The present application successfully solves the traditional contradiction that the adhesive is either brittle when hard or sticky when soft. The examples obtain high hardness (manifested as low abrasion amount and high tensile-shear strength) while still maintaining excellent toughness (toughened by VAE) and interface stability, thereby realizing long service life and high-quality surface treatment effect (device bright without blackening) under severe polishing conditions.

[0052] Specifically, from the data in Table 1, it can be seen that the performance of Comparative Example 1 (milk white glue type I (RF601)) is as follows: all test indicators are poor, the strength retention rate after heat aging is only 58%, the service life is only 30 hours, and the abrasion amount is as high as 0.095 g.

[0053] Mechanism analysis: The comparative example is a pure polyvinyl acetate (PVAc) homopolymer, whose molecular chain is highly polar and contains a large number of ester groups, which are easy to form hydrogen bonds with water molecules, resulting in a very high equilibrium water absorption rate (usually > 30%); high water absorption rate makes its mechanical strength drop sharply in a humid environment or when heated (water acts as a plasticizer); its glass transition temperature (Tg) is low (about 28°C), and at the high temperature (> 120°C) generated by polishing, the polymer chain segment moves violently, the film is seriously softened and sticky, and the binding force to the fiber is lost, resulting in blackening of the fly silk and workpiece. At the same time, PVAc relies only on weak physical adsorption and limited hydrogen bonding between the fiber and the fiber, and the interfacial bonding force is weak, and the hardness is low and not wear-resistant. Therefore, it embodies the inherent defects of traditional water-based adhesives in terms of temperature resistance, water resistance, wear resistance and interfacial bonding, and is the object to be surpassed and replaced by the present application.

[0054] As can be seen from the data in Table 1, the performance of Comparative Example 2 (without silane coupling agent KH-570) is: the tensile shear strength (7.2 MPa) is significantly lower than that of Example 1 (8.8 MPa), which is about 18% lower; the polishing wheel life (65 h) is also significantly shortened; and its aging retention rate (92%) is acceptable. This shows that KH-570 plays a key role as a "molecular bridge" in the present application. Its one end of the molecule participates in copolymerization to chemically bond the siloxane structural unit to the polymer main chain; the other end of the molecule is hydrolyzed to silanol during curing, which can not only condense with the silanol of the silica sol, but also condense with the hydroxyl (-OH) on the surface of the sisal fiber to form a firm Si-O-C covalent bond. The lack of KH-570 means that the adhesive and the fiber lose this high-strength, water-resistant and heat-resistant chemical bond connection, mainly relying on physical and mechanical interlocking and hydrogen bonding, resulting in a significant reduction in interfacial bonding strength. In addition, the siloxane structure bonded on the polymer chain can also improve the hydrophobicity of the polymer and reduce the water absorption rate. Therefore, the strength and durability of Comparative Example 2 are reduced, which directly proves the key role of functional monomers in strengthening the interface through chemical bonding.

[0055] From the data in Table 1, it can be seen that the performance of Comparative Example 3 (without silica sol) is: heat resistance significantly deteriorated (strength retention rate 72%), wear resistance deteriorated (wear amount 0.055 g), tensile shear strength (6.5 MPa) is low, and service life (48 h) is greatly shortened. This shows that the silica sol in the present application provides three key roles: inorganic temperature-resistant skeleton, hard wear-resistant filler, and interfacial physical reinforcing agent. Heat resistance: the abundant silicon hydroxyl groups on the surface of nano-SiO2 particles form a dense hydrogen bond network with carboxyl and hydroxyl groups on the polymer chain. The thermal stability of this inorganic network is much higher than that of the organic polymer chain, and it can effectively "pin" and inhibit the movement of the polymer chain when heated, thereby significantly improving the heat distortion temperature and high temperature modulus of the adhesive film, which is the main reason for the improvement of heat aging resistance; wear resistance: high-hardness nano-SiO2 particles are uniformly dispersed in the polymer matrix, directly bearing the friction load, greatly improving the surface hardness and scratch resistance of the adhesive film; interface and strength: nano-particles can penetrate into the micropores of the sisal fibers, producing an anchoring effect and enhancing physical interlocking; at the same time, the surface silicon hydroxyl groups form strong hydrogen bonds with the fiber hydroxyl groups, enhancing the interfacial interaction. The absence of silica sol means the loss of inorganic reinforcing phase, and the adhesive system returns to ordinary organic polymer blend, its heat resistance, hardness and physical anchoring ability to the fiber naturally return to a lower level.

[0056] From the data in Table 1, it can be seen that the performance of Comparative Example 4 (without VAE emulsion) is: tensile shear strength (8.0 MPa) is acceptable, heat retention rate (98%) is excellent, wear amount (0.027 g) is very low, but polishing wheel service life (70 h) is significantly lower than Example 1 (82 h). This shows that the VAE emulsion in the present application mainly plays the role of toughening agent and wetting agent. The ethylene segments in the VAE molecular chain impart excellent flexibility and elasticity; in the continuous phase composed of harder vinyl-acetate-silica sol, VAE can form dispersed "islands" or co-construct interpenetrating networks (IPN), when the adhesive layer is subjected to repeated impact and shear stress in polishing operation, the flexible VAE phase can absorb and disperse energy through deformation, preventing the initiation and propagation of micro-cracks, thereby improving the fracture toughness and fatigue resistance of the adhesive layer. Comparative Example 4 lacks this toughening mechanism, the adhesive layer is brittle, and internal damage is more likely to occur and accumulate under long-term dynamic load, resulting in premature failure, thus the service life is shortened; VAE emulsion has excellent wettability on porous and rough surfaces, which can promote rapid and deep penetration of the adhesive solution into the sisal fiber bundle, ensuring more uniform and firm bonding.

[0057] From the data in Table 1, it can be seen that the performance of Comparative Example 5 (MMA dosage is too low) is as follows: all-round performance degradation: strength retention rate (75%), tensile shear strength (6.0 MPa), wear resistance (0.070g), and service life (40h) are far inferior to the examples. This shows that methyl methacrylate (MMA) as a "hard monomer" is the core component to improve the rigidity, heat resistance and water resistance of the product of the application; the MMA homopolymer has a Tg as high as 105°C, and when it is copolymerized with VAc, it can effectively raise the overall Tg of the copolymer, which is the basis of heat resistance; the side chain of MMA is a hydrophobic methyl group, which can form an effective hydrophobic shielding layer around the molecular chain when it reaches a certain proportion in the polymer chain, greatly hindering the diffusion and penetration of water molecules into the polymer interior, thereby reducing the equilibrium water absorption of the film from 40% of pure PVAc to below 5%. Low water absorption is the key to maintaining high strength stability and aging resistance at high temperatures; MMA contributes to the rigidity of the chain segment, improving the hardness and compression modulus of the film. In Comparative Example 5, the amount of MMA is only 2 parts (much lower than the optimal range of 10-20 parts), resulting in a copolymer property closer to that of PVAc, thus losing its heat resistance, moisture resistance and hardness, and the performance approaches that of Comparative Example 1, but is slightly better than that of pure PVAc (as there is still a small amount of BA and AA).

[0058] From the data in Table 1, it can be seen that the performance of Comparative Example 6 (KH-570 physically mixed, not copolymerized) is as follows: its performance (strength 7.5 MPa, retention rate 85%, wear 0.040g, service life 60h) is between Example 1 and Comparative Example 2, but is significantly inferior to Example 1. This comparative example is very convincing, as it reveals the essential difference and importance between in-situ chemical copolymerization and simple physical blending. In Example 1, KH-570 participates in polymerization through double bonds, and its silanol groups are uniformly and firmly chemically bonded to specific positions on the polymer chain, becoming an inherent part of the polymer. During curing, these "pre-set" reaction sites can efficiently and directionally react with the fiber surface; in Comparative Example 6, KH-570 is physically dispersed in the system as a small molecule, which may have uneven distribution, easy migration to the surface or interface, etc. Although it can also react with the fiber and silica sol, it cannot "anchor" the large polymer chain to the fiber as it is not chemically connected to the polymer backbone. It is more like an independent "small molecule glue" existing in the interface area, and its connection efficiency and carrying capacity are much lower than that of the "anchor point" connected to the entire polymer network through chemical bonds. Therefore, the performance of Comparative Example 6 is better than that of Comparative Example 2 without KH-570 (proving that physical addition also has some effect), but is significantly inferior to Example 1 in which KH-570 participates in copolymerization. This strongly proves the creativity and necessity of introducing functional monomers into the polymer chain through copolymerization, which is the most optimal process path to achieve a high-strength and durable interface.

[0059] Figure 2is the comparison chart of the wear degree of the sisal polishing wheel made of the sizing glue in Example 1 and Comparative Example 1 after polishing for 1 hour. The results are described: the sisal wheel on the left side of the figure (labeled white or corresponding to Example 1) maintains a relatively complete shape after polishing, with uniform wear, and the surface of the metal workpiece polished by it is bright without dark marks. The sisal wheel on the right side of the figure (corresponding to Comparative Example 1) has obvious fiber shedding and loose structure, and may even be accompanied by glue coking and adhesion, and the surface of the workpiece polished by it has dark stripes or is dark (black) as a whole.

[0060] This comparison chart intuitively and visually demonstrates the core advantages of the sizing glue of the application in terms of high temperature resistance and wear resistance. High temperature resistance: the glue film of Comparative Example 1 (ordinary white latex) softens, becomes sticky and even degrades under high temperature generated by high-speed polishing. The softened glue cannot effectively bind the sisal fibers, resulting in "flying silk"; at the same time, the sticky and degraded glue and the shed fibers can contaminate the high-temperature metal surface, and under the action of friction oxidation, visible "darkening" phenomenon is formed. The glue film of Example 1 still maintains sufficient hardness and morphological stability under the same high temperature due to the heat-resistant network constructed by MMA and silica sol, thereby avoiding glue softening contamination and abnormal fiber shedding, and ensuring the smoothness of the workpiece surface. Wear resistance and structural integrity: the glue film of Comparative Example 1 has poor hardness and wear resistance, which not only causes its own rapid wear, but also causes the holding force of the fibers to rapidly decay in friction, resulting in a collapsed damage of the wheel structure (fibers shed in pieces). The glue film of Example 1 has high hardness, good wear resistance, and is firmly combined with the fibers (chemical bond + physical interlocking), so the wear mode is uniform and gradual, and the wheel structure remains intact during the test, showing a longer service life and stable polishing effect. Figure 2 is the visual demonstration of the performance data (such as wear amount, service life, and workpiece effect) in Table 1, which vividly embodies how the sizing glue of the application solves the two major pain points of traditional adhesives, i.e. heat softening and poor wear resistance, and finally achieves the dual goals of improving the service life of the polishing wheel and ensuring the polishing quality.

[0061] It should be understood that the application of the application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the application.

Claims

1. A sisal polishing wheel shaping adhesive, characterized in that, The product comprises, by weight parts: 100 parts of vinyl acetate emulsion, 5-20 parts of silica sol, 10-20 parts of ethylene-vinyl acetate copolymer emulsion, and 0.5-2 parts of thickener; the raw materials of the vinyl acetate emulsion include: deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, functional monomers, anionic emulsifiers, nonionic emulsifiers, oxidants, and reducing agents.

2. The sisal polishing wheel shaping adhesive according to claim 1, characterized in that, The raw materials of the vinyl acetate-acrylic emulsion, by mass parts, include: 100 parts deionized water; 50-70 parts vinyl acetate; 1-6 parts butyl acrylate; 10-20 parts methyl methacrylate; 1-3 parts acrylic acid; 1-10 parts functional monomers; 0.5-2 parts anionic emulsifier; 0.1-2 parts nonionic emulsifier; 0.1-0.2 parts oxidant; and 0.1-0.2 parts reducing agent.

3. The sisal polishing wheel shaping adhesive according to claim 2, characterized in that, The anionic emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, disodium fatty alcohol polyoxyethylene ether sulfosuccinate monoester, and sodium dodecyl diphenyl ether disulfonate.

4. The sisal polishing wheel shaping adhesive according to claim 2, characterized in that, The nonionic emulsifier is one or both of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether.

5. The sisal polishing wheel shaping adhesive according to claim 2, characterized in that, The functional monomer is one or more of silane coupling agents, hydroxypropyl acrylate, and N-hydroxymethylacrylamide.

6. The sisal polishing wheel shaping adhesive according to claim 5, characterized in that, The silane coupling agent is γ-methacryloxypropyltrimethoxysilane.

7. The sisal polishing wheel shaping adhesive according to claim 2, characterized in that, The oxidizing agent is one or more of sodium persulfate, ammonium persulfate, and potassium persulfate; the reducing agent is one or a mixture of two of sodium formaldehyde sulfoxylate and sodium bisulfite.

8. The sisal polishing wheel shaping adhesive according to claim 1, characterized in that, The silica sol has a particle size of 10-30 nm and a solid content of 20-40%; the ethylene-vinyl acetate copolymer emulsion has a vinyl acetate content of 65-75% and a solid content of 45-55%.

9. The sisal polishing wheel shaping adhesive according to claim 1, characterized in that, The thickener is a polyacrylic acid-based alkali-swelling thickener or a polyurethane-based associative thickener.

10. A method for preparing the sisal polishing wheel shaping adhesive as described in any one of claims 1-9, characterized in that, Including the following steps: Preparation of acrylic emulsion: Pre-emulsification: Add 60-80% of the total mass of deionized water, vinyl acetate, butyl acrylate, methyl methacrylate, acrylic acid, functional monomers, 60-80% of the total mass of anionic emulsifier and nonionic emulsifier to a pre-emulsification kettle according to the formula. Stir at 800-1500 rpm for 20-40 minutes at room temperature and pressure to obtain a uniform and stable pre-emulsion. Seed polymerization: Add the remaining deionized water and remaining anionic emulsifier to the reactor, heat to 78-82℃, then add 5-15% of the total mass of the pre-emulsion as seed solution, followed by 40-60% of the total mass of oxidant and 40-60% of the total mass of reducing agent, and react at 78-82℃ for 20-40 minutes; Droplet polymerization: Maintain the reaction temperature at 75-80℃, and simultaneously begin to drop the remaining pre-emulsion into the reactor, while adding the remaining oxidant and reducing agent dropwise at the same time, controlling the dropping time to 240-300 minutes; Post-processing: After the addition is complete, keep warm at 75-80℃ for 40-60 minutes, then cool down to 45-55℃ and discharge to obtain the acetic acid-propylene emulsion; The styling adhesive is prepared by mixing the acrylic emulsion, silica sol, ethylene-vinyl acetate copolymer emulsion and thickener in a certain proportion under stirring conditions to obtain the sisal polishing wheel styling adhesive.

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