High-precision wear-resistant filtering material coated with nano coating and preparation method of high-precision wear-resistant filtering material

Abstract

The invention relates to the technical field of filtering materials, in particular to a high-precision wear-resistant filtering material coated with a nano-coating and a preparation method thereof.Non-woven fabric serves as a filtering supporting layer, the surface of the filtering supporting layer is coated with nano-silica sol dispersion liquid, heat setting is conducted, an upper filtering surface layer is formed, and the filtering material is obtained; the prepared upper filtering surface layer has a three-dimensional structure, and the average pore size of the upper filtering surface layer is controlled to be 5-10 microns; the preparation method comprises the following steps: mixing nano silica sol, a PTFE emulsion, an acrylic emulsion, a fluorocarbon surfactant, a silane coupling agent, a film-forming agent and deionized water to obtain a nano silica sol dispersion liquid; a self-repairing polyurethane emulsion is used as a film-forming agent, polytetrahydrofuran and isophorone diisocyanate are used as raw materials to synthesize a prepolymer, 2, 2-dimethylolpropionic acid is used as a hydrophilic chain extender, and modified nano zinc oxide and glycylglycine methyl ester are used as end-capping reagents.

Description

Technical Field

[0001] The present invention relates to the technical field of filter materials, and specifically to a high-precision wear-resistant filter material coated with a nano-coating and a preparation method thereof. Background Art

[0002] In modern industrial production, air filtration and industrial waste gas treatment are important issues. With the development of technology, the performance requirements for filter materials are becoming increasingly stringent. Traditional filter materials have limitations in filtration accuracy due to problems such as uneven pore size distribution and single material structure.

[0003] In addition, ordinary filter materials have poor wear resistance and antibacterial properties, cannot withstand frequent mechanical friction and air flow impact for a long time, are prone to breakage in a short time, and require frequent replacement of filter materials, which not only increases costs but also leads to unstable operation of the filtration system and affects the continuity of production.

[0004] For example, a composite filter material and a preparation method thereof are disclosed in Patent CN202110605769.6, which is prepared by impregnating a needle-punched felt in an aramid nanofiber dispersion liquid and drying. Although the mechanical properties and filtration performance of the filter material are improved, a three-dimensional network structure cannot be formed inside, and it is difficult to ensure the emission of flue gas concentration at 10mg / Nm 3 For example, a highly wear-resistant and fold-resistant glass fiber composite filter material and a preparation method thereof are disclosed in Patent CN202310476580.0, which is prepared by dispersing a composite impregnation liquid into a glass fiber composite filter material through an impregnation-rolling process and drying. Although the wear resistance and fold resistance of the glass fiber composite filter material are improved, the filtration effect and antibacterial property of the material have not been significantly improved. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-precision wear-resistant filter material coated with a nano-coating and a preparation method thereof to solve the problems in the prior art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method of a high-precision wear-resistant filter material coated with a nano-coating, comprising the following steps: S1: Mix nano-silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film-forming agent, and deionized water to obtain a nano-silica sol dispersion liquid; S2: Use non-woven fabric as a filter support layer, coat the nano-silica sol dispersion liquid on the surface of the filter support layer, and perform heat setting to form an upper filter surface layer, thereby obtaining a high-precision wear-resistant filter material coated with a nano-coating.

[0007] Further, the working conditions for heat setting are as follows: the temperature in zones 1 - 3 is 160 - 180 °C, the temperature in zones 4 - 6 is 180 - 200 °C, the temperature in zones 6 - 8 is 200 - 220 °C, and the vehicle speed is 5 - 7 m / min.

[0008] Further, by mass fraction, the composition of the nano - silica sol dispersion is: 10 - 30 parts of nano - silica sol, 20 - 40 parts of PTFE emulsion, 5 - 20 parts of acrylic emulsion, 0.5 - 2 parts of fluorocarbon surfactant, 0.5 - 2 parts of silane coupling agent, 0.5 - 2 parts of film - forming agent, and 10 - 60 parts of deionized water.

[0009] Further, the filter support layer is one or several composite non - woven fabrics selected from PPS non - woven fabric, aramid non - woven fabric, polyester non - woven fabric, PTFE non - woven fabric, and fiberglass non - woven fabric.

[0010] Further, the grammage of the filter support layer is 400 - 800 g / m 2 , and the thickness is 1 - 3 mm; the pore size of the upper - layer filter surface layer is 5 - 10 µm, and the thickness of the upper - layer filter surface layer is 0.5 - 2 µm.

[0011] Further, the particle size of the nano - silica sol is 8 - 15 nm.

[0012] Further, the film - forming agent is one of polyurethane, acrylic acid, and epoxy resin.

[0013] Further, the film - forming agent is a self - repairing polyurethane emulsion, and its preparation includes the following steps: Under a nitrogen atmosphere, mix polytetrahydrofuran, isophorone diisocyanate, and dibutyltin dilaurate, keep warm at 78 - 82 °C for 40 - 60 min, add a mixture of 2,2 - dimethylolpropionic acid and N,N - dimethylformamide, continue to keep warm for 80 - 100 min, add a mixture of modified nano - zinc oxide and N,N - dimethylformamide, cool down to 35 - 40 °C, add triethylamine, keep warm for 40 - 60 min, add a mixture of glycylglycine methyl ester and N,N - dimethylformamide, keep warm in an ice - water bath for 2 - 3 h, and emulsify with deionized water for 1 - 2 h to obtain a self - repairing polyurethane emulsion with a solid content of 20 - 30%.

[0014] Further, the preparation of the modified nano - zinc oxide includes the following steps: (1) Mix ethanol and deionized water, add nano - zinc oxide, adjust the pH value to 4, ultrasonically disperse for 8 - 10 min, add γ - mercaptopropyltrimethoxysilane, keep warm at 78 - 82 °C for 10 - 12 h, centrifuge, wash, and dry to obtain mercapto - functionalized nano - zinc oxide; (2) Gallic acid, anhydrous ethanol and butyl acetate are mixed, triphenylphosphine and 4-methoxyphenol are added, and then glycidyl methacrylate is added, and the mixture is kept warm at 95-105°C for 5-6 hours, and the mixture is washed with water, separated and rotary evaporated to obtain gallic acid-glycidyl methacrylate; (3) Gallic acid-glycidyl methacrylate and N,N-dimethylformamide are mixed, ultrasonically stirred for 20-30 min, thiolated nano zinc oxide is added, the temperature is raised to 45-50°C, ultrasonically stirred for 20-30 min, a photoinitiator is added, 365 nm ultraviolet light is used for 5-7 h, washed, rotary evaporated, and dried to obtain modified nano zinc oxide.

[0015] Further, the preparation of glycylglycine methyl ester comprises the following steps: Mix thionyl chloride and methanol, stir in an ice bath for 50-70 minutes, add diglycine peptide, keep warm at 18-25°C for 2-3 hours, keep warm at 63-67°C for 110-130 minutes, and rotary evaporate to obtain glycylglycine methyl ester hydrochloride; mix N,N-dimethylformamide, triethylamine, and glycylglycine methyl ester hydrochloride, filter, and obtain glycylglycine methyl ester.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a high-precision wear-resistant filter material coated with a nano-coating and a preparation method thereof. Through component structure and process design, the prepared filter material has a high-precision filtering effect, can cope with the emission of particles with a particle size of 5μm, and has excellent wear resistance, antibacterial properties, and thermal stability. Its internal structure will not be damaged or fail during long-term use under harsh working conditions.

[0017] A non-woven fabric is used as a filter support layer, and a nano-silica sol dispersion is coated on the surface of the filter support layer, and heat-set to form an upper filter surface layer to obtain a filter material, wherein the introduction of the nano-silica sol dispersion makes the filter material have excellent thermal stability, UV resistance, and wear resistance; by controlling the process parameters, the prepared upper filter surface layer has a three-dimensional structure, so that after being subjected to powder-free spraying at a pressure of 5 Bar for 10,000 times, the average surface pore size retention rate is above 99%, and by controlling the average pore size of the upper filter surface layer to 5-10μm, the filtering effect and durability of the filter material are improved, and the effect of high efficiency and low resistance is achieved; a non-woven fabric is used as a filter support layer, and by limiting the thickness and strength of the non-woven fabric, it provides stable support for the filter material.

[0018] Mix nano-silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film-forming agent and deionized water to obtain a nano-silica sol dispersion; the introduction of nano-silica sol improves the wear resistance and chemical stability of the material while adjusting the porosity and pore size of the coating. The introduction of PTFE emulsion enhances the chemical stability and heat resistance of the coating. Adding acrylic emulsion can improve the original physical properties of the filter material. The introduction of fluorocarbon surfactant is beneficial to improving the dispersion effect of PTFE emulsion and is more conducive to forming a three-dimensional network structure. The addition of silane coupling agent can improve the interfacial bonding between nano-silica sol and PTFE emulsion and acrylic emulsion, and improve the integrity and uniformity of the coating; by controlling the introduction amount of each substance and the heat setting parameters, it is beneficial to improve the performance of the filter material.

[0019] In order to further improve the ultraviolet resistance, antibacterial property and durability of the filter material and endow the upper filter surface layer with self-healing property, a self-healing polyurethane emulsion is introduced as a film-forming agent into the nano-silica sol dispersion. A prepolymer is synthesized using polytetrahydrofuran and isophorone diisocyanate as raw materials, 2,2-dimethylolpropionic acid as a hydrophilic chain extender, and modified nano-zinc oxide and glycylglycine methyl ester as end-capping agents. The modified nano-zinc oxide is prepared by first mercapto-functionalizing nano-zinc oxide with γ-mercaptopropyltrimethoxysilane and then grafting gallic acid-glycidyl methacrylate with antibacterial activity through a photo-click reaction, so as to improve the binding strength between the ultraviolet-resistant agent and antibacterial agent nano-zinc oxide and the self-healing polyurethane emulsion, and endow the filter material with long-term antibacterial and ultraviolet resistance; among them, glycylglycine methyl ester is a dipeptide compound synthesized using diglycine as a raw material. End-capping the polyurethane can trigger terminal triple hydrogen bonds, making it have good self-healing property at room temperature, thereby improving the service life of the filter material. Detailed implementation mode

[0020] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] It should be noted that if there are directional indications such as up, down, left, right, front, and back in the embodiments of the present invention, these directional indications are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture. If this specific posture changes, the directional indications will also change accordingly. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0023] Embodiment 1: A preparation method of a high-precision wear-resistant filter material coated with a nano-coating, comprising the following steps: S1: Mix nano-silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film-forming agent, and deionized water to obtain a nano-silica sol dispersion; S2: Use non-woven fabric as the filter support layer, coat the nano-silica sol dispersion on the surface of the filter support layer, and perform heat setting to form an upper filter surface layer, thereby obtaining a high-precision wear-resistant filter material coated with a nano-coating; The working conditions for heat setting: the temperature in zones 1-3 is 160 °C, the temperature in zones 4-6 is 180 °C, the temperature in zones 6-8 is 200 °C, and the vehicle speed is 5 m / min; By mass, the composition of the nano-silica sol dispersion is: 10 parts of nano-silica sol, 20 parts of PTFE emulsion, 5 parts of acrylic emulsion, 0.5 part of fluorocarbon surfactant, 0.5 part of silane coupling agent, 0.5 part of film-forming agent, and 10 parts of deionized water; The filter support layer is PPS non-woven fabric; The grammage of the filter support layer is 550 g / m 2 , with a thickness of 2 mm; the thickness of the upper filter surface layer is 1 µm; the film-forming agent is polyurethane.

[0024] Embodiment 2: A preparation method of a high-precision wear-resistant filter material coated with a nano-coating, comprising the following steps: S1: Mix nano-silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film-forming agent, and deionized water to obtain a nano-silica sol dispersion; S2: Use non-woven fabric as the filter support layer, coat the nano-silica sol dispersion on the surface of the filter support layer, and perform heat setting to form an upper filter surface layer, thereby obtaining a high-precision wear-resistant filter material coated with a nano-coating; Working conditions for heat setting: temperature in zones 1 - 3 is 170 °C, temperature in zones 4 - 6 is 190 °C, temperature in zones 6 - 8 is 210 °C, and vehicle speed is 6 m / min; By mass fraction, the composition of the nano - silica sol dispersion is: 20 parts of nano - silica sol, 30 parts of PTFE emulsion, 10 parts of acrylic emulsion, 1 part of fluorocarbon surfactant, 1 part of silane coupling agent, 1 part of film - forming agent, and 37 parts of deionized water; The filter support layer is PPS non - woven fabric; The grammage of the filter support layer is 550 g / m 2 , and the thickness is 2 mm; the thickness of the upper - layer filter surface layer is 1 µm; The film - forming agent is polyurethane.

[0025] Example 3: A preparation method of a high - precision wear - resistant filter material coated with a nano - coating, comprising the following steps: S1: Mix nano - silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film - forming agent, and deionized water to obtain a nano - silica sol dispersion; S2: Use non - woven fabric as the filter support layer, coat the nano - silica sol dispersion on the surface of the filter support layer, and perform heat setting to form the upper - layer filter surface layer, thereby obtaining a high - precision wear - resistant filter material coated with a nano - coating; Working conditions for heat setting: temperature in zones 1 - 3 is 180 °C, temperature in zones 4 - 6 is 200 °C, temperature in zones 6 - 8 is 220 °C, and vehicle speed is 7 m / min; By mass fraction, the composition of the nano - silica sol dispersion is: 30 parts of nano - silica sol, 40 parts of PTFE emulsion, 20 parts of acrylic emulsion, 2 parts of fluorocarbon surfactant, 2 parts of silane coupling agent, 2 parts of film - forming agent, and 60 parts of deionized water; The filter support layer is PPS non - woven fabric; The grammage of the filter support layer is 550 g / m 2 , and the thickness is 2 mm; the thickness of the upper - layer filter surface layer is 1 µm; The film - forming agent is polyurethane.

[0026] Example 4: A preparation method of a high - precision wear - resistant filter material coated with a nano - coating, comprising the following steps: S1: Mix nano - silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film - forming agent, and deionized water to obtain a nano - silica sol dispersion; S2: Use non - woven fabric as the filter support layer, coat the nano - silica sol dispersion on the surface of the filter support layer, and perform heat setting to form the upper - layer filter surface layer, thereby obtaining a high - precision wear - resistant filter material coated with a nano - coating; Working conditions for heat setting: the temperature in zones 1 - 3 is 170 °C, the temperature in zones 4 - 6 is 190 °C, the temperature in zones 6 - 8 is 210 °C, and the vehicle speed is 6 m / min; By mass fraction, the composition of the nano - silica sol dispersion is: 20 parts of nano - silica sol, 30 parts of PTFE emulsion, 10 parts of acrylic emulsion, 1 part of fluorocarbon surfactant, 1 part of silane coupling agent, 1 part of film - forming agent, and 37 parts of deionized water; The filter support layer is PPS non - woven fabric; The grammage of the filter support layer is 550 g / m 2 , and the thickness is 2 mm; the thickness of the upper - layer filter surface layer is 1 µm; The film - forming agent is a self - healing polyurethane emulsion, and its preparation includes the following steps: Under a nitrogen atmosphere, 5.2 g of polytetrahydrofuran, 3.5 g of isophorone diisocyanate, and 1 drop of dibutyltin dilaurate are mixed, kept at 78 °C for 60 min, then a mixture of 0.7 g of 2,2 - dimethylolpropionic acid and 3 mL of N,N - dimethylformamide is added, and it is kept warm for another 80 min. Then a mixture of 0.8 g of modified nano - zinc oxide and 6 mL of N,N - dimethylformamide is added, the temperature is cooled to 35 °C, 0.2 g of triethylamine is added, and it is kept warm for 40 min. Then a mixture of 1.4 g of glycylglycine methyl ester and 6 mL of N,N - dimethylformamide is added, kept in an ice - water bath for 2 h, and emulsified with deionized water for 1 h to obtain a self - healing polyurethane emulsion with a solid content of 20%; The preparation of the modified nano - zinc oxide includes the following steps: (1) 60 g of ethanol and 20 g of deionized water are mixed, 0.5 g of nano - zinc oxide is added, the pH value is adjusted to 4, ultrasonically dispersed for 8 min, 2 mL of γ - mercaptopropyltrimethoxysilane is added, kept at 78 °C for 12 h, centrifuged, washed, and dried to obtain mercapto - functionalized nano - zinc oxide; (2) 1.7 g of gallic acid, 20 mL of absolute ethanol, and 40 mL of butyl acetate are mixed, 9 mg of triphenylphosphine and 10 mg of 4 - methoxyphenol are added, then 2.8 g of glycidyl methacrylate is added, kept at 95 °C for 6 h, washed with water, separated by liquid - liquid extraction, and rotary evaporated to obtain gallic acid - glycidyl methacrylate; (3) 2.5 g of gallic acid - glycidyl methacrylate and 30 mL of N,N - dimethylformamide are mixed, ultrasonically stirred for 20 min, 1.8 g of mercapto - functionalized nano - zinc oxide is added, the temperature is raised to 45 °C, ultrasonically stirred for 20 min, 0.1 g of photo - initiator is added, irradiated with 365 nm ultraviolet light for 5 h, washed, rotary evaporated, and dried to obtain modified nano - zinc oxide; The preparation of the glycylglycine methyl ester includes the following steps: Mix 6.2 mL of thionyl chloride and 75 mL of methanol, stir for 50 min in an ice bath, add 6.6 g of diglycine, keep warm at 18 °C for 3 h, keep warm at 63 °C for 130 min, and perform rotary evaporation to obtain glycylglycine methyl ester hydrochloride; mix 25 mL of N,N-dimethylformamide, 1 mmol of triethylamine, and 1 mmol of glycylglycine methyl ester hydrochloride, and filter to obtain glycylglycine methyl ester.

[0027] Example 5: A preparation method of a high-precision wear-resistant filter material coated with a nano-coating, comprising the following steps: S1: Mix nano-silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film-forming agent, and deionized water to obtain a nano-silica sol dispersion; S2: Use non-woven fabric as the filter support layer, coat the nano-silica sol dispersion on the surface of the filter support layer, and perform heat setting to form an upper filter surface layer, thereby obtaining a high-precision wear-resistant filter material coated with a nano-coating; The working conditions of heat setting: the temperature in zones 1-3 is 170 °C, the temperature in zones 4-6 is 190 °C, the temperature in zones 6-8 is 210 °C, and the vehicle speed is 6 m / min; By mass, the composition of the nano-silica sol dispersion is: 20 parts of nano-silica sol, 30 parts of PTFE emulsion, 10 parts of acrylic emulsion, 1 part of fluorocarbon surfactant, 1 part of silane coupling agent, 1 part of film-forming agent, and 37 parts of deionized water; The filter support layer is PPS non-woven fabric; The grammage of the filter support layer is 550 g / m 2 , the thickness is 2 mm; the thickness of the upper filter surface layer is 1 µm; The film-forming agent is a self-healing polyurethane emulsion, and its preparation includes the following steps: Under a nitrogen atmosphere, mix 5.2 g of polytetrahydrofuran, 3.5 g of isophorone diisocyanate, and 1 drop of dibutyltin dilaurate, keep warm at 80 °C for 50 min, add a mixture of 0.7 g of 2,2-dimethylolpropionic acid and 3 mL of N,N-dimethylformamide, continue to keep warm for 90 min, add a mixture of 0.8 g of modified nano-zinc oxide and 6 mL of N,N-dimethylformamide, cool down to 38 °C, add 0.2 g of triethylamine, keep warm for 50 min, add a mixture of 1.4 g of glycylglycine methyl ester and 6 mL of N,N-dimethylformamide, keep warm in an ice-water bath for 2.5 h, and emulsify with deionized water for 1.5 h to obtain a self-healing polyurethane emulsion with a solid content of 25%; The preparation of the modified nano-zinc oxide includes the following steps: (1) Mix 60 g of ethanol and 20 g of deionized water, add 0.5 g of nano-zinc oxide, adjust the pH value to 4, ultrasonically disperse for 9 min, add 2 mL of γ-mercaptopropyltrimethoxysilane, keep warm at 80 °C for 11 h, centrifuge, wash, and dry to obtain mercapto-functionalized nano-zinc oxide; (2) Mix 1.7 g of gallic acid, 20 mL of absolute ethanol, and 40 mL of butyl acetate, add 9 mg of triphenylphosphine and 10 mg of 4-methoxyphenol, then add 2.8 g of glycidyl methacrylate, keep warm at 100 °C for 5.5 h, wash with water and separate the liquid, rotary evaporate to obtain gallic acid-glycidyl methacrylate; (3) Mix 2.5 g of gallic acid-glycidyl methacrylate and 30 mL of N,N-dimethylformamide, ultrasonically stir for 25 min, add 1.8 g of mercapto-functionalized nano-zinc oxide, raise the temperature to 48 °C, ultrasonically stir for 25 min, add 0.1 g of photoinitiator, irradiate with 365 nm ultraviolet light for 6 h, wash, rotary evaporate, and dry to obtain modified nano-zinc oxide; The preparation of the glycylglycine methyl ester includes the following steps: Mix 6.2 mL of thionyl chloride and 75 mL of methanol, stir in an ice bath for 60 min, add 6.6 g of diglycine, keep warm at 20 °C for 2.5 h, keep warm at 65 °C for 120 min, rotary evaporate to obtain glycylglycine methyl ester hydrochloride; Mix 25 mL of N,N-dimethylformamide, 1 mmol of triethylamine, and 1 mmol of glycylglycine methyl ester hydrochloride, filter to obtain glycylglycine methyl ester.

[0028] Example 6: A preparation method of a high-precision wear-resistant filter material coated with a nano-coating, comprising the following steps: S1: Mix nano-silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film-forming agent, and deionized water to obtain a nano-silica sol dispersion; S2: Use non-woven fabric as the filter support layer, coat the nano-silica sol dispersion on the surface of the filter support layer, and perform heat setting to form an upper filter surface layer to obtain a high-precision wear-resistant filter material coated with a nano-coating; Working conditions for heat setting: the temperature in zones 1-3 is 170 °C, the temperature in zones 4-6 is 190 °C, the temperature in zones 6-8 is 210 °C, and the vehicle speed is 6 m / min; By mass, the composition of the nano-silica sol dispersion is: 20 parts of nano-silica sol, 30 parts of PTFE emulsion, 10 parts of acrylic emulsion, 1 part of fluorocarbon surfactant, 1 part of silane coupling agent, 1 part of film-forming agent, and 37 parts of deionized water; The filter support layer is PPS non-woven fabric; The grammage of the filter support layer is 550 g / m 2, with a thickness of 2 mm; the thickness of the upper filtering surface layer is 1 µm; The film-forming agent is a self-healing polyurethane emulsion, and its preparation includes the following steps: Under a nitrogen atmosphere, 5.2 g of polytetrahydrofuran, 3.5 g of isophorone diisocyanate, and 1 drop of dibutyltin dilaurate are mixed, kept at 82 °C for 40 min, then a mixture of 0.7 g of 2,2-dimethylolpropionic acid and 3 mL of N,N-dimethylformamide is added, and the mixture is further kept at 82 °C for 100 min. Then, a mixture of 0.8 g of modified nano-zinc oxide and 6 mL of N,N-dimethylformamide is added, the temperature is lowered to 40 °C, 0.2 g of triethylamine is added, and the mixture is kept at 40 °C for 60 min. Next, a mixture of 1.4 g of glycylglycine methyl ester and 6 mL of N,N-dimethylformamide is added, and the mixture is kept in an ice bath for 3 h, followed by emulsification with deionized water for 2 h to obtain a self-healing polyurethane emulsion with a solid content of 30%; The preparation of the modified nano-zinc oxide includes the following steps: (1) 60 g of ethanol and 20 g of deionized water are mixed, 0.5 g of nano-zinc oxide is added, the pH value is adjusted to 4, and the mixture is ultrasonically dispersed for 10 min. Then, 2 mL of γ-mercaptopropyltrimethoxysilane is added, and the mixture is kept at 82 °C for 10 h, followed by centrifugation, washing, and drying to obtain mercapto-functionalized nano-zinc oxide; (2) 1.7 g of gallic acid, 20 mL of absolute ethanol, and 40 mL of butyl acetate are mixed, 9 mg of triphenylphosphine and 10 mg of 4-methoxyphenol are added, and then 2.8 g of glycidyl methacrylate is added. The mixture is kept at 105 °C for 5 h, followed by washing with water, liquid separation, and rotary evaporation to obtain gallic acid-glycidyl methacrylate; (3) 2.5 g of gallic acid-glycidyl methacrylate and 30 mL of N,N-dimethylformamide are mixed, ultrasonically stirred for 30 min, 1.8 g of mercapto-functionalized nano-zinc oxide is added, the temperature is raised to 50 °C, and the mixture is ultrasonically stirred for 30 min. Then, 0.1 g of photoinitiator is added, and the mixture is irradiated with ultraviolet light at 365 nm for 7 h, followed by washing, rotary evaporation, and drying to obtain modified nano-zinc oxide; The preparation of the glycylglycine methyl ester includes the following steps: 6.2 mL of thionyl chloride and 75 mL of methanol are mixed, stirred in an ice bath for 70 min, 6.6 g of diglycine is added, and the mixture is kept at 25 °C for 2 h and then at 67 °C for 110 min. Rotary evaporation is carried out to obtain glycylglycine methyl ester hydrochloride; 25 mL of N,N-dimethylformamide, 1 mmol of triethylamine, and 1 mmol of glycylglycine methyl ester hydrochloride are mixed and filtered to obtain glycylglycine methyl ester.

[0029] Comparative Example 1: Taking Example 2 as the control group, the thickness of the upper filtering surface layer is 0.4 µm, and other processes are normal.

[0030] Comparative Example 2: Taking Example 2 as the control group, the particle size of the nano-silica sol is 20 nm (Z3020, Linyi Zhixuan New Materials Co., Ltd.), and other processes are normal.

[0031] Comparative Example 3: Taking Example 2 as the control group, by mass, the composition of the nano-silica sol dispersion is: 10 parts of nano-silica sol, 40 parts of PTFE emulsion, 5 parts of acrylic emulsion, and 45 parts of deionized water, and other processes are normal.

[0032] Comparative Example 4: Taking Example 6 as the control group, modified nano-zinc oxide was not prepared, and other processes are normal.

[0033] Comparative Example 5: Taking Example 6 as the control group, glycylglycine methyl ester was not prepared, and other processes are normal.

[0034] Sources of raw materials used (only as demonstration examples): Nano-silica sol JN-30 (8 - 15 nm): Jinan Haiwei Chemical Co., Ltd.; PTFE emulsion ST801AW NC010: DuPont, USA; Acrylic emulsion (60%), Photoinitiator (Benzophenone 119 - 61 - 9): Suzhou Senfeida Chemical Co., Ltd.; Polyurethane 001: Langfang Wanteng Anticorrosive Materials Co., Ltd.; Fluorocarbon surfactant (FC - 4430): Huizhou Dongxinda Chemical Co., Ltd.; Silane coupling agent (γ-mercaptopropyltrimethoxysilane) M100619, Polytetrahydrofuran P118599, Isophorone diisocyanate I109582, Dibutyltin dilaurate D100274, 2,2-Dimethylolpropionic acid B104539, Triethylamine T103285, Nano-zinc oxide Z112847, Gallic acid G131992, Triphenylphosphine T104478, 4-Methoxyphenol M170858, Glycidyl methacrylate G106686, Glycylglycine G119491: Aladdin Reagent; Ethanol, Butyl acetate, Thionyl chloride, Methanol, N,N-Dimethylformamide, analytical pure: commercially available.

[0035] Performance test: Test the materials prepared in the examples and comparative examples: Filtration performance: Measured with reference to VDI3926, the size diameter is 150 mm, the filtration air velocity is 2 m / min, and the inlet dust concentration is 5 g / m 3 , The experimental sequence is 30 cycles at the initial stage, 5000 cycles of stabilization, and 30 cycles at the end; 30 cycles at the initial stage and 30 cycles at the end: When the pressure difference between the two sides of the filter material reaches 1000 Pa, pulsed air is used to clean the dust on the surface of the filter material, and then the next process is carried out, repeating 30 times. 5000 cycles of stabilization: The cleaning pressure is 5 bar, and the cleaning is carried out once every 5 s, with a number of 5000 times; The calculation formula for the outlet dust concentration is: C = M / (1.85×t / 3600), and the unit is mg / m3 , the cycle time s is the total time spent in the last 30 cycles; Wear resistance: measured with reference to GB / T21196.2-2007, using Martindale abrasion tester, pressure of 12kPa, sample diameter of 38mm, NO.600 water sandpaper as abrasive, abrasive diameter of 140mm, and then observe whether there are problems such as coating damage. If there is no damage for 5200-5300 times, it is qualified (including 5200), less than 5200 times is unqualified, 5300-5500 times is good (including 5300), and greater than or equal to 5500 times is excellent: the results are shown in Table 1; Table 1

[0036] Antibacterial persistence: Examples 4-6 and Comparative Examples 4-5 were tested: irradiated with a UV lamp with a wavelength of 254 nm for 72 hours, tested with reference to GB / T21866-2008, using Staphylococcus aureus as the test strain, and measuring the antibacterial rate using the plate method; the results are shown in Table 2; Table 2

[0037] The present invention provides a high-precision wear-resistant filter material coated with a nano-coating and a preparation method thereof. Through component structure and process design, the prepared filter material has a high-precision filtering effect, can cope with the emission of particles with a particle size of 5μm, and has excellent wear resistance, antibacterial properties, and thermal stability. Its internal structure will not be damaged or fail during long-term use under harsh working conditions.

[0038] By comparing Example 2 with Comparative Example 1, it can be seen that the thickness of the upper filter surface layer is within the preferred range, and the obtained filter material has high capture efficiency, low outlet concentration, long cycle time and good wear resistance; By comparing Example 2 with Comparative Example 2, it can be seen that the particle size of the nano-silica sol is within the preferred range, and the obtained filter material has high capture efficiency, low outlet concentration, long cycle time and good wear resistance; By comparing Example 2 with Comparative Example 3, it can be seen that the latter fails to form a three-dimensional network structure, and the obtained filter material has low capture efficiency, high outlet concentration and low cycle time.

[0039] Comparing Example 6 with Comparative Example 4 and Comparative Example 5, it can be seen that in order to further improve the ultraviolet resistance, antibacterial property and durability of the filter material and endow the upper filter surface layer with self-healing property, a self-healing polyurethane emulsion is introduced as a film-forming agent into the nano-silica sol dispersion liquid. A prepolymer is synthesized from polytetrahydrofuran and isophorone diisocyanate, 2,2-dimethylolpropionic acid is used as a hydrophilic chain extender, and modified nano-zinc oxide and glycylglycine methyl ester are used as capping agents. The modified nano-zinc oxide is prepared by first mercapto-functionalizing nano-zinc oxide with γ-mercaptopropyltrimethoxysilane and then grafting gallic acid-glycidyl methacrylate with antibacterial activity through a photo-click reaction, so as to improve the binding strength between the ultraviolet-resistant agent and antibacterial agent nano-zinc oxide and the self-healing polyurethane emulsion, and endow the filter material with long-term antibacterial property and ultraviolet resistance; glycylglycine methyl ester is a dipeptide compound synthesized from diglycine. Capping the polyurethane can trigger terminal triple hydrogen bonds, endowing it with good self-healing property at room temperature, thereby increasing the service life of the filter material.

[0040] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural transformations made under the inventive concept of the present invention by using the description of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a high-precision wear-resistant filter material coated with a nano-coating, characterized in that: The following steps are involved: S1: mixing nano silica sol, PTFE emulsion, acrylic emulsion, fluorocarbon surfactant, silane coupling agent, film-forming agent and deionized water to obtain nano silica sol dispersion; S2: Using non-woven fabric as the filter support layer, coating the nano-silica sol dispersion on the surface of the filter support layer, heat setting, forming an upper filter surface layer, and obtaining a high-precision wear-resistant filter material coated with a nano-coating.

2. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 1, characterized in that: Working conditions for heat setting: temperature of zones 1-3 is 160-180℃, temperature of zones 4-6 is 180-200℃, temperature of zones 6-8 is 200-220℃, and vehicle speed is 5-7m / min.

3. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 1, characterized in that: The nano-silica sol dispersion comprises, by weight, 10-30 parts of nano-silica sol, 20-40 parts of PTFE emulsion, 5-20 parts of acrylic emulsion, 0.5-2 parts of fluorocarbon surfactant, 0.5-2 parts of silane coupling agent, 0.5-2 parts of film-forming agent and 10-60 parts of deionized water.

4. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 1, characterized in that: The filtering support layer is one or more composite non-woven fabrics selected from the group consisting of PPS non-woven fabric, aramid non-woven fabric, polyester non-woven fabric, PTFE non-woven fabric and glass fiber non-woven fabric.

5. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 1, characterized in that: The gram weight of the filter support layer is 400-800g / m 2 , thickness is 1-3mm; the pore size distribution of the upper filter surface layer is 5-10μm, and the thickness of the upper filter surface layer is 0.5-2µm.

6. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 1, characterized in that: The film-forming agent is one of polyurethane, acrylic acid and epoxy resin.

7. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 1, characterized in that: The film former is a self-repairing polyurethane emulsion, and the preparation thereof comprises the following steps: In a nitrogen atmosphere, polytetrahydrofuran, isophorone diisocyanate and dibutyltin dilaurate are mixed, and the mixture is kept at 78-82°C for 40-60 minutes. A mixed solution of 2,2-dihydroxymethylpropionic acid and N,N-dimethylformamide is added, and the mixture is kept warm for 80-100 minutes. A mixed solution of modified nano zinc oxide and N,N-dimethylformamide is added, and the temperature is lowered to 35-40°C. Triethylamine is added and the mixture is kept warm for 40-60 minutes. A mixed solution of glycylglycine methyl ester and N,N-dimethylformamide is added, and the mixture is kept warm in an ice water bath for 2-3 hours. Deionized water is added for emulsification for 1-2 hours to obtain a self-healing polyurethane emulsion.

8. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 7, characterized in that: The preparation of modified nano zinc oxide includes the following steps: (1) Mix ethanol and deionized water, add nano zinc oxide, adjust the pH value to 4, perform ultrasonic dispersion for 8-10 minutes, add γ-mercaptopropyltrimethoxysilane, keep warm at 78-82°C for 10-12 hours, centrifuge, wash, and dry to obtain thiolated nano zinc oxide; (2) Gallic acid, anhydrous ethanol and butyl acetate are mixed, triphenylphosphine and 4-methoxyphenol are added, and then glycidyl methacrylate is added, and the mixture is kept warm at 95-105°C for 5-6 hours, and the mixture is washed with water, separated and rotary evaporated to obtain gallic acid-glycidyl methacrylate; (3) Gallic acid-glycidyl methacrylate and N,N-dimethylformamide are mixed, ultrasonically stirred for 20-30 min, thiolated nano zinc oxide is added, the temperature is raised to 45-50°C, ultrasonically stirred for 20-30 min, a photoinitiator is added, 365 nm ultraviolet light is used for 5-7 h, washed, rotary evaporated, and dried to obtain modified nano zinc oxide.

9. The method for preparing a high-precision wear-resistant filter material coated with a nano-coating according to claim 7, characterized in that: The preparation of the glycylglycine methyl ester comprises the following steps: Mix thionyl chloride and methanol, stir in an ice bath for 50-70 minutes, add diglycine peptide, keep warm at 18-25°C for 2-3 hours, keep warm at 63-67°C for 110-130 minutes, and rotary evaporate to obtain glycylglycine methyl ester hydrochloride; mix N,N-dimethylformamide, triethylamine, and glycylglycine methyl ester hydrochloride, filter, and obtain glycylglycine methyl ester.

10. A high-precision wear-resistant filter material coated with a nano-coating, characterized in that: The filter material is prepared by the preparation method described in any one of claims 1 to 9, and is applied to the fields of air filtration and industrial waste gas treatment.

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