Preparation method of high anti-humidity and high dust-holding capacity glass fiber high-efficiency air filtration material

Abstract

The present invention belongs to the technical field of filtration and separation, and more specifically, relates to a preparation method of a high moisture-resistant and high dust-holding capacity glass fiber high-efficiency air filtration material. First, a protective film is formed on the surface of the chopped glass fiber, and then, using the principle of chemical etching, uniform pits are formed on the surface of the glass fiber. At the same time, a hydrophobic polymer material is attached to the fiber surface to reduce the surface free energy of the fiber. The combination of the two forms a superhydrophobic effect, greatly improving the overall moisture resistance of the glass fiber filter material, enabling it to maintain high-efficiency filtration in a high-humidity environment, effectively extending the service life, and being widely applicable to the air filtration fields of gas power plant intake systems, electronics, biopharmaceuticals and other industries.

Description

Technical Field

[0001] The present invention belongs to the technical field of filtration and separation, and more specifically, relates to a preparation method of a high moisture-resistant and high dust-holding glass fiber high-efficiency air filtration material. Background Art

[0002] In various fields such as electric power, electronics, biopharmaceuticals, beverage and food, high-efficiency air filters (above E10 level according to the EN1822-1:2009 classification method) are essential key components, which effectively improve the air cleanliness and ensure the product quality and the stability of equipment operation. The core determining the performance of high-efficiency air filters is the filtration material. The high-efficiency filtration materials of traditional technologies mainly include the following several types: 1. Surface composite electrospun nanofiber filtration materials, the main disadvantages of such materials are low dust-holding capacity and easy to break; 2. Surface composite microporous membrane filtration materials, the main disadvantage of such materials is low dust-holding capacity; 3. Wet-process glass fiber high-efficiency filtration materials, the main disadvantage of such materials is poor moisture resistance. The filtration materials with poor moisture resistance will form a paste after being affected by moisture, causing the pressure drop of the filter element to rise sharply and the service life to be greatly shortened; the filtration materials with low dust-holding capacity will reach the terminal pressure drop in a short time.

[0003] Therefore, it is of great significance to develop a high-efficiency air filtration material with both high moisture resistance and high dust-holding capacity. Summary of the Invention

[0004] Aiming at the defects of the prior art, the purpose of the present invention is to provide a preparation method of a high moisture-resistant and high dust-holding glass fiber high-efficiency air filtration material to solve the technical problems such as the low dust-holding capacity of the existing air filtration material reaching the terminal pressure drop in a short time and the rapid increase of resistance in a humid environment due to poor moisture resistance.

[0005] To achieve the above purpose, the present invention provides a preparation method of a high moisture-resistant and high dust-holding glass fiber high-efficiency air filtration material, including the following steps:

[0006] (1) By weight, mix 20-40 parts of stearic acid, 20-30 parts of tetraethylenepentamine, 15-25 parts of cationic surfactant, and 5-35 parts of silane coupling agent, heat them to react, cool down, add glacial acetic acid, and then react for several hours to obtain a protective film reaction product;

[0007] (2) Dilute the protective film reaction product obtained in step (1) with water to a mass percentage concentration of 5-10% to obtain a protective film diluent;

[0008] (3) Immerse the chopped glass fiber in the protective film diluent obtained in step (2), and dry the immersed chopped glass fiber to obtain chopped glass fiber with a protective film formed on the surface;

[0009] (4) mixing the chopped glass fibers with the protective film formed on the surface in step (3) with a hydrofluoric acid solution, and introducing compressed air to partially etch the protective film; then separating the solid from the liquid, and washing the solid surface with deionized water to neutrality to obtain chopped glass fibers with partially etched surfaces;

[0010] (5) fully mixing the chopped glass fibers and micro glass fibers whose surfaces are partially etched in step (4) with water to form a suspension; and dehydrating to form a wet paper sheet after solid-liquid separation to remove impurities;

[0011] (6) Mixing and stirring the waterproofing agent emulsion, the adhesive emulsion and the anionic surfactant until foam is generated; then applying the foam to the surface of the wet paper sheet in step (5); and drying and curing the wet paper sheet with foam to obtain the air filter material.

[0012] Preferably, in step (1), 20 to 40 parts of stearic acid, 20 to 30 parts of tetraethylenepentamine, 15 to 25 parts of a cationic surfactant, and 5 to 35 parts of a silane coupling agent are mixed, and the mixture is first reacted at 140 to 160° C. for 1 to 1.5 hours, and then heated to 180 to 200° C. for 2 to 3 hours; after cooling to 40 to 60° C., glacial acetic acid is added and reacted for 2 to 3 hours to obtain a protective film reaction product.

[0013] Preferably, the cationic surfactant in step (1) is a fatty amine salt.

[0014] Preferably, in step (3), the chopped glass fibers are immersed in the protective film dilution solution of step (2) for 10 to 20 minutes, and then the immersed chopped glass fibers are dried at 100 to 120° C. for 5 to 10 minutes to obtain chopped glass fibers with a protective film formed on the surface.

[0015] Preferably, in step (4), the chopped glass fibers with a protective film formed on the surface in step (3) are added to a 10-30 vol% hydrofluoric acid solution, and compressed air is introduced into the hydrofluoric acid solution for 10-20 minutes to partially etch the protective film.

[0016] Preferably, the chopped glass fibers in step (3) have a diameter of 6 to 10 μm and a length of 10 to 12 mm; and the microglass fibers in step (5) are composed of two or more glass fiber wools with different beating degrees and a beating degree of 19°SR to 59°SR.

[0017] Preferably, in step (5), the surface-partially etched chopped glass fibers and the micro glass fibers described in step (4) are first mixed with water to prepare a suspension with a concentration of 0.1-0.5 wt%, and ultrasonically dispersed for 10-15 min; the mass ratio of the surface-partially etched chopped glass fibers to the micro glass fibers is 1:9-3:7; then the dispersed suspension is further diluted to a concentration of 0.02-0.05 wt%; after solid-liquid separation to remove impurities, vacuum dehydration is performed to form a wet paper sheet.

[0018] Preferably, in step (6), the waterproofing agent emulsion and the adhesive emulsion are mixed and stirred evenly and diluted to a mass concentration of 5-10%, then an anionic surfactant is added, and stirring is performed for 5-10 min to generate foam.

[0019] Preferably, in step (6), the foam is coated on the wet paper sheet described in step (5), and the coating thickness is 1-2 cm.

[0020] Preferably, the drying in step (6) is specifically: drying at 80-100 °C for 0.5-3 min; the curing is specifically: curing at 150-180 °C for 3-6 min.

[0021] Generally speaking, compared with the prior art by the above technical solution conceived by the present invention, the following beneficial effects are obtained:

[0022] (1) The air filtration material of the present invention forms a protective film on the surface of the glass fiber first and then uses the principle of chemical etching to form uniformly distributed pits on the surface of the glass fiber. At the same time, a hydrophobic polymer material is attached to the fiber surface, reducing the surface free energy of the fiber. The combination of the two forms a superhydrophobic effect, greatly improving the overall moisture resistance of the glass fiber filter material, enabling it to maintain high-efficiency filtration in a high-humidity environment, effectively extending the service life, and being widely applicable to the air filtration fields of gas power plant intake systems, electronics, biopharmaceuticals and other industries.

[0023] (2) The air filtration material of the present invention forms a protective film on the surface of the glass fiber through the reaction of stearic acid, tetraethylenepentamine, cationic surfactant, and silane coupling agent, so that when hydrofluoric acid etches on the surface of the glass fiber, it will not corrode the entire surface, but etch out uniformly distributed pits, achieving an effect that is difficult to form by direct etching with hydrofluoric acid.

[0024] (3) The present invention makes the chopped glass fibers on the surface form uniformly distributed pits, which increases the filtration function of the chopped glass fibers that only play a skeleton support role in traditional glass fiber filter materials. More small particles are intercepted by the pits during filtration, thereby improving the efficiency and dust holding capacity of the filtration material and extending the service life of the filtration material.

[0025] (4) The present invention forms a foam with the waterproofing agent emulsion and the binder emulsion and then applies it to the surface of the wet paper fiber. Compared with the traditional techniques of directly impregnating, coating, spraying, etc., the waterproofing agent and binder components carried by the foam are small and uniform. After drying and solidification, a uniformly distributed adhesive film can be formed on the fiber surface, which will not block the original pore channels too much. Therefore, the filter material of the present invention has good hydrophobic properties as a whole and has high air permeability, which effectively extends the service life. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] The present invention provides a method for preparing a high-moisture-resistance and high-dust-holding glass fiber high-efficiency air filter material, comprising the following steps:

[0028] (1) According to weight parts, 20 to 40 parts of stearic acid, 20 to 30 parts of tetraethylenepentamine, 15 to 25 parts of cationic surfactant, and 5 to 35 parts of silane coupling agent are mixed and heated to react, and after cooling, glacial acetic acid is added and reacted for several hours to obtain a protective film reaction product;

[0029] (2) diluting the protective film reaction product of step (1) with water to a mass percentage concentration of 5 to 10% to obtain a protective film dilution solution;

[0030] (3) impregnating the chopped glass fibers in the protective film dilution solution of step (2), and drying the impregnated chopped glass fibers to obtain chopped glass fibers with a protective film formed on the surface;

[0031] (4) mixing the chopped glass fibers with the protective film formed on the surface in step (3) with a hydrofluoric acid solution, and introducing compressed air to partially etch the protective film; then separating the solid from the liquid, and washing the solid surface with deionized water to neutrality to obtain chopped glass fibers with partially etched surfaces;

[0032] (5) fully mixing the chopped glass fibers and micro glass fibers whose surfaces are partially etched in step (4) with water to form a suspension; and dehydrating to form a wet paper sheet after solid-liquid separation to remove impurities;

[0033] (6) Mixing and stirring the waterproofing agent emulsion, the adhesive emulsion and the anionic surfactant until foam is generated; then applying the foam to the wet paper sheet of step (5); drying and curing the wet paper sheet with foam to obtain the air filter material.

[0034] In some embodiments, in step (1), 20 to 40 parts of stearic acid, 20 to 30 parts of tetraethylenepentamine, 15 to 25 parts of a cationic surfactant, and 5 to 35 parts of a silane coupling agent are mixed. First, the mixture is reacted at 140 to 160 °C for 1 to 1.5 h, then heated to 180 to 200 °C and reacted for 2 to 3 h. After cooling to 40 to 60 °C, glacial acetic acid is added and the reaction is carried out for 2 to 3 h to obtain a protective film reaction product.

[0035] In some embodiments, the cationic surfactant in step (1) is a fatty amine salt, including but not limited to fatty amide propyl dimethylamine, fatty alkyl dimethyl benzyl ammonium halide, etc.

[0036] In some embodiments, in step (3), the chopped glass fibers are impregnated in the protective film diluent described in step (2) for 10 to 20 min, and then the impregnated chopped glass fibers are dried at 100 to 120 °C for 5 to 10 min to obtain chopped glass fibers with a protective film formed on the surface.

[0037] In some embodiments, in step (4), the chopped glass fibers with a protective film formed on the surface described in step (3) are added to a 10 to 30 vol% hydrofluoric acid solution, and at the same time, compressed air is introduced into the hydrofluoric acid solution for 10 to 20 min to partially etch the protective film. The compressed air plays a stirring role in the solution to make the fibers fully contact with the hydrofluoric acid. In some embodiments, the pressure of the compressed air is 0.3 to 0.6 MPa.

[0038] In some embodiments, the diameter of the chopped glass fibers in step (5) is 6 to 10 μm and the length is 10 to 12 mm; the micro glass fibers are composed of two or more glass fiber cottons with different beating degrees and the beating degrees are 19 to 59 °SR. The specific specifications and proportions are selected according to the efficiency requirements of the filter material.

[0039] In some embodiments, in step (5), first, the chopped glass fibers with the surface partially etched described in step (4) and the micro glass fibers are mixed with water according to a mass ratio of 1:9 to 3:7 to prepare a suspension with a concentration of 0.1 to 0.5 wt%, and ultrasonic dispersion is carried out for 10 to 15 min; then the dispersed suspension is further diluted to a concentration of 0.02 to 0.05 wt%; after solid-liquid separation to remove impurities, vacuum dehydration is carried out to form a wet paper sheet.

[0040] In some embodiments, the impurities in the chopped glass fibers and micro glass fibers with a larger density (in the solid phase) are removed by solid-liquid separation, and then the liquid phase (containing water, chopped glass fibers and micro glass fibers) obtained by solid-liquid separation is sent to an inclined wire former for vacuum dehydration to form a wet paper sheet. The water content in the wet paper sheet is generally 80 to 90 wt%.

[0041] In some embodiments, in step (6), the waterproofing agent emulsion and the binder emulsion are mixed and stirred evenly and diluted to a mass concentration of 5-10%, then an anionic surfactant is added, and stirred for 5-10 min to generate foam. In some embodiments, the volume percentage of the added anionic surfactant is 30-50%.

[0042] In some embodiments, the waterproofing agent emulsion is a water-soluble emulsion of silicone oil, long-chain fatty acid, and perfluorosilane; the solid content of the waterproofing agent emulsion is 20-40%; the binder emulsion is selected from at least one of a copolymer emulsion of styrene and acrylic acid, an acrylic polymer emulsion, and a vinyl acetate emulsion; the solid content of the binder emulsion is 50-70%; the mass ratio of the waterproofing agent emulsion to the binder emulsion is 1:1-5:1; the anionic surfactant is one or more of fatty alcohol polyoxyethylene ether sulfate, sulfonated fatty acid ester salt, fatty alcohol sulfate, secondary alkyl sulfonate, etc. The silane coupling agent can be various commonly used silane coupling agents, including but not limited to vinyltriethoxysilane, vinyltrimethoxysilane, or vinyltris(β-methoxyethoxy)silane, etc.

[0043] In some embodiments, in step (6), the foam is coated on the wet paper sheet in step (5), and the coating thickness is 1-2 cm. The foam can be coated on the surface of the wet paper sheet in various ways. For example, the foam can be scraped onto the wet paper sheet with a squeegee, or the foam can be blown onto the wet paper sheet with compressed air, or other methods can also be used.

[0044] In some embodiments, the drying in step (6) is specifically: drying at 80-100 °C for 0.5-3 min; the curing is specifically: curing at 150-180 °C for 3-6 min.

[0045] In the experimental process of the present invention, initially, the steps of preparing the protective film from step (1) to step (3) were not set, and the glass fiber was directly etched with hydrofluoric acid. It was found that the whole fiber was corroded and did not achieve the expected effect. Later, various substances were also tried as the protective film, and it was found that none of them achieved the expected effect. It was not until the product obtained by the reaction of various substances in step (1) of the present invention was used as the protective film that the effect was finally achieved. Moreover, in the initial stage of the experiment, the waterproofing agent emulsion and the binder emulsion were tried to be attached to the wet paper sheet directly by various methods such as dipping, curtain coating, spraying, etc. After drying, it was found that the air permeability was poor. It was not until the idea of adding an anionic surfactant to form foam and then applying it to the surface of the wet paper sheet fibers that the high anti-wet and high dust-holding glass fiber high-efficiency air filtration material of the present invention was finally obtained.

[0046] The preparation method of a high moisture-resistant and high dust-holding capacity glass fiber high-efficiency air filtration material provided by the present invention is scientifically and reasonably designed. The prepared air filtration material not only meets the economic use requirements of long service life, but also can meet any filtration efficiency requirements, and at the same time avoids the problem that the resistance of traditional glass fiber air filtration materials increases too fast in humid environments due to poor moisture resistance. This filtration material is applicable to various high-efficiency air filtration occasions. While maintaining high-efficiency filtration, it greatly extends the service life, reduces the cost of filter element replacement and the manual work intensity.

[0047] Example 1

[0048] In this example, the average diameter of the chopped glass fiber is 6 μm and the average length is 12 mm; the micro glass fiber is a mixture of glass fiber cotton with beating degrees of 34°SR and 59°SR in a mass ratio of 5:1; the waterproofing agent emulsion is an emulsion obtained by dissolving a water-based nonionic fluorocarbon surfactant containing a six-carbon fluorine chain (carbon six waterproofing agent, model TG5671) in water, and the solid content is 30%; the binder emulsion is an acrylic polymer emulsion with a molecular weight of 4×10 5 , and the solid content is 60%; the mass ratio of the waterproofing agent emulsion to the binder emulsion is 1:1; the anionic surfactant is sodium lauryl polyoxyethylene ether sulfate.

[0049] This example also provides a preparation method of the air filtration material, which specifically includes the following steps:

[0050] 1) React 30% stearic acid, 30% tetraethylenepentamine, 25% fatty amide propyl dimethylamine, and 15% vinyltrimethoxysilane at 150 °C for 1 h according to the mass ratio, then heat to 180 °C and react for 2 h, cool down to 50 °C, and add glacial acetic acid in a proportion twice the molar amount of tetraethylenepentamine and react for 2 h;

[0051] 2) Add deionized water to dissolve the reaction product of 1), and dilute the concentration to 5 wt%;

[0052] 3) Immerse the chopped glass fiber in the diluted solution in 2) for 10 min, then filter off the diluted solution, and dry the chopped glass fiber at 120 °C for 5 min;

[0053] 4) Add the dried chopped glass fiber into a 10 vol% hydrofluoric acid solution, and at the same time introduce compressed air into the solution, the pressure of the compressed air is 0.5 MPa, and continue for 10 min;

[0054] 5) Filter off the excess acid solution, and rinse the fiber surface with deionized water until it is neutral;

[0055] 6) Prepare a suspension with a concentration of 0.5 wt% by mixing the rinsed chopped glass fibers, micro glass fibers and water, and disperse it using ultrasound for 10 min; the mass ratio of the chopped glass fibers to the micro glass fibers is 3:7.

[0056] 7) Further dilute the dispersed suspension to a concentration of 0.03 wt%, remove impurities from the diluted suspension and perform vacuum dehydration to form a wet paper sheet.

[0057] 8) Mix the waterproofing agent emulsion and the binder emulsion evenly at a mass ratio of 1:1, dilute to a mass concentration of 5%, pour into a container, and add an anionic surfactant with a volume of 50% of it, stir for 8 min until rich foam is generated.

[0058] 9) Use a scraper to scrape the foam described in 8) onto the wet paper sheet described in 7), and control the thickness at 1.5 cm.

[0059] 10) Dry the wet paper sheet with foam at 80 °C for 2 min, and then cure it at 150 °C for 3 min to obtain the air filtration material.

[0060] Example 2

[0061] In this example, the average diameter of the chopped glass fibers is 6 μm and the average length is 12 mm; the micro glass fibers are a mixture of glass fiber cotton with beating degrees of 34°SR and 59°SR in a mass ratio of 5:1; the waterproofing agent is an aqueous non-ionic fluorocarbon surfactant containing a six-carbon fluorine chain (the same as in Example 1), and the solid content is 30%; the binder is an acrylic polymer emulsion with a molecular weight of 4×10 5 , and the solid content is 60%; the mass ratio of the waterproofing agent emulsion to the binder emulsion is 1:1; the anionic surfactant is sodium lauryl polyoxyethylene ether sulfate.

[0062] This example also provides a preparation method of the air filtration material, which specifically includes the following steps:

[0063] 1) React 25% stearic acid, 25% tetraethylenepentamine, 25% fatty amide propyl dimethylamine, and 25% vinyltrimethoxysilane at 150 °C for 1 h according to the mass ratio, then heat to 180 °C and react for 2 h, cool down to 40 °C, and add glacial acetic acid in a proportion twice the molar amount of tetraethylenepentamine and react for 2 h.

[0064] 2) Add deionized water to dissolve the reaction product of 1), and dilute the concentration to 5 wt%.

[0065] 3) Immerse the chopped glass fibers in the dilution in 2) for 10 min, then filter off the dilution, and dry the chopped glass fibers at 120 °C for 5 min.

[0066] 4) Add the dried chopped glass fibers into a 20 vol% hydrofluoric acid solution, and at the same time, introduce compressed air into the solution for 10 min;

[0067] 5) Filter out the excess acid solution, and rinse the fiber surface with deionized water until it is neutral;

[0068] 6) Prepare a suspension with a concentration of 0.5 wt% by mixing the rinsed chopped glass fibers, micro glass fibers and water, and disperse it with ultrasonic waves for 10 min; the mass ratio of chopped glass fibers to micro glass fibers is 3:7.

[0069] 7) Further dilute the dispersed suspension to a concentration of 0.03 wt%, remove impurities from the diluted suspension and perform vacuum dehydration to form a wet paper sheet;

[0070] 8) Mix the waterproofing agent emulsion and the adhesive emulsion evenly at a mass ratio of 1:1, dilute them to a mass concentration of 5%, pour them into a container, and add 40 vol% of an anionic surfactant, and stir for 8 min until rich foam is generated;

[0071] 9) Use a squeegee to scrape the foam described in 8) onto the wet paper sheet described in 7), and control the thickness at 1.5 cm;

[0072] 10) Dry the wet paper sheet with foam at 80 °C for 2 min, and then cure it at 150 °C for 3 min to obtain the air filtration material.

[0073] Example 3

[0074] In this example, the average diameter of the chopped glass fibers is 6 μm, and the average length is 12 mm; the micro glass fibers are a mixture of glass fiber cotton with beating degrees of 34° SR and 59° SR in a mass ratio of 5:1; the waterproofing agent is an aqueous non-ionic fluorocarbon surfactant containing a six-carbon fluorine chain (the same as in Example 1), and the solid content is 30%; the binder is an acrylic polymer emulsion with a molecular weight of 4×10 5 , and the solid content is 60%; the mass ratio of the waterproofing agent emulsion to the adhesive emulsion is 1:1; the anionic surfactant is sodium lauryl ether sulfate.

[0075] This example also provides a preparation method of the air filtration material, which specifically includes the following steps:

[0076] 1) React 25% stearic acid, 25% tetraethylenepentamine, 25% fatty amide propyl dimethylamine, and 25% vinyltrimethoxysilane at 150 °C for 1 h according to the mass ratio, then heat to 180 °C and react for 2 h, cool down to 40 °C, and add glacial acetic acid in a ratio of 2 times the molar amount of tetraethylenepentamine, and react for 2 h;

[0077] 2) Dissolve the reaction product in deionized water and dilute the concentration to 5 wt%.

[0078] 3) Add chopped glass fibers to the diluted solution in 2) and impregnate for 10 min, then filter off the diluted solution and dry the chopped glass fibers at 120 °C for 5 min.

[0079] 4) Add the dried chopped glass fibers to a 30 vol% hydrofluoric acid solution, and at the same time introduce compressed air into the solution for 10 min.

[0080] 5) Filter off the excess acid solution and rinse the fiber surface with deionized water until neutral.

[0081] 6) Prepare a suspension with a concentration of 0.5 wt% by mixing the rinsed chopped glass fibers, micro glass fibers and water, and disperse it with ultrasonic waves for 10 min; the mass ratio of chopped glass fibers to micro glass fibers is 3:7.

[0082] 7) Further dilute the dispersed suspension to a concentration of 0.03 wt%, remove the slag from the diluted suspension and perform vacuum dehydration to form a wet paper sheet.

[0083] 8) Mix the waterproofing agent emulsion and the binder emulsion evenly and dilute to a mass concentration of 5%, then pour it into a container, add 40 vol% anionic surfactant, and stir for 8 min until rich foam is produced.

[0084] 9) Use a squeegee to scrape the foam described in 8) onto the wet paper sheet described in 7), and control the thickness at 1.5 cm.

[0085] 10) Dry the wet paper sheet with foam at 80 °C for 2 min, and then cure it at 150 °C for 3 min to obtain the air filtration material.

[0086] Example 4

[0087] In this example, the average diameter of the chopped glass fibers is 6 μm and the average length is 12 mm; the micro glass fibers are a mixture of glass fiber cotton with beating degrees of 34 °SR and 59 °SR in a mass ratio of 5:1; the waterproofing agent is an aqueous non-ionic fluorocarbon surfactant containing a six-carbon fluorine chain (the same as in Example 1), and the solid content is 30%; the binder is an acrylic polymer emulsion with a molecular weight of 4×10 5 , and the solid content is 60%; the mass ratio of the waterproofing agent emulsion to the binder emulsion is 1:1; the anionic surfactant is sodium lauryl ether sulfate.

[0088] This example also provides a method for preparing an air filtration material, which specifically includes the following steps:

[0089] 1) React 30% stearic acid, 30% tetraethylenepentamine, 25% fatty amide propyl dimethylamine, and 15% vinyltrimethoxysilane at 150 °C for 1 h, then heat to 180 °C and react for 2 h. Cool down to 50 °C and add glacial acetic acid in a proportion twice the molar amount of tetraethylenepentamine, and react for 2 h;

[0090] 2) Dissolve the reaction product of 1) in deionized water and dilute the concentration to 5 wt%;

[0091] 3) Immerse the chopped glass fibers in the diluted solution of 2) for 10 min, then filter off the diluted solution and dry the chopped glass fibers at 120 °C for 5 min;

[0092] 4) Add the dried chopped glass fibers into a 10 vol% hydrofluoric acid solution, and simultaneously introduce compressed air into the solution for 10 min;

[0093] 5) Filter off the excess acid solution and rinse the fiber surface with deionized water until neutral;

[0094] 6) Prepare a suspension with a concentration of 0.5 wt% by mixing the rinsed chopped glass fibers, micro glass fibers and water, and disperse it with ultrasonic waves for 10 min; the mass ratio of chopped glass fibers to micro glass fibers is 3:7.

[0095] 7) Further dilute the dispersed suspension to a concentration of 0.03 wt%, remove the slag from the diluted suspension and perform vacuum dehydration to form a wet paper sheet;

[0096] 8) Mix the waterproofing agent emulsion and the binder emulsion evenly and dilute to a mass concentration of 8%, then pour it into a container, add 45% Vol anionic surfactant, and stir for 8 min until rich foam is produced;

[0097] 9) Use a squeegee to scrape the foam described in 8) onto the wet paper sheet described in 7), and control the thickness at 1.5 cm;

[0098] 10) Dry the wet paper sheet with foam at 80 °C for 2 min, and then cure it at 150 °C for 3 min to obtain the air filtration material.

[0099] Example 5

[0100] In this example, the average diameter of the chopped glass fibers is 6 μm and the average length is 12 mm; the micro glass fibers are a mixture of glass fiber cotton with beating degrees of 34 °SR and 59 °SR in a mass ratio of 5:1; the waterproofing agent is an aqueous non-ionic fluorocarbon surfactant containing a six-carbon fluorine chain (the same as in Example 1), and the solid content is 30%; the binder is an acrylic polymer emulsion with a molecular weight of 4×10 5, the solid content is 60%; the mass ratio of the waterproofing agent emulsion to the adhesive emulsion is 1:1; the anionic surfactant is sodium lauryl polyoxyethylene ether sulfate.

[0101] This example also provides a preparation method of the air filter material, which specifically includes the following steps:

[0102] 1) React 30% stearic acid, 30% tetraethylenepentamine, 25% fatty amide propyl dimethylamine, and 15% vinyltrimethoxysilane at 150 °C for 1 h according to the mass ratio, then heat to 180 °C and react for 2 h, cool down to 50 °C, and add glacial acetic acid in a ratio of 2 times the molar amount of tetraethylenepentamine and react for 2 h;

[0103] 2) Add deionized water to dissolve the reaction product of 1), and dilute the concentration to 5 wt%;

[0104] 3) Immerse the chopped glass fibers in the diluted solution of 2) for 10 min, then filter off the diluted solution, and dry the chopped glass fibers at 120 °C for 5 min;

[0105] 4) Add the dried chopped glass fibers into a 10 vol% hydrofluoric acid solution, and at the same time introduce compressed air into the solution for 10 min;

[0106] 5) Filter off the excess acid solution, and rinse the fiber surface with deionized water until neutral;

[0107] 6) Prepare a suspension with a concentration of 0.5 wt% by mixing the rinsed chopped glass fibers, micro glass fibers and water, and disperse it with ultrasonic waves for 10 min; the mass ratio of the chopped glass fibers to the micro glass fibers is 3:7.

[0108] 7) Further dilute the dispersed suspension to a concentration of 0.03 wt%, remove impurities from the diluted suspension and perform vacuum dehydration to form a wet paper sheet;

[0109] 8) Mix the waterproofing agent emulsion and the adhesive emulsion evenly and dilute to a mass concentration of 10%, pour them into a container, and add 35% Vol of anionic surfactant, stir for 8 min until rich foam is generated;

[0110] 9) Use a scraper to scrape the foam described in 8) onto the wet paper sheet described in 7), and control the thickness at 1.5 cm;

[0111] 10) Dry the wet paper sheet with foam at 80 °C for 2 min, and then cure it at 150 °C for 3 min to obtain the air filter material.

[0112] Comparative Example 1

[0113] Other steps are the same as those in Example 1. The difference between this comparative example and Example 1 is that steps 1) to 3) are not included in the preparation method.

[0114] Comparative Example 2

[0115] Other steps are the same as those in Example 1. The difference between this comparative example and Example 1 is that in the preparation method, in step 8), there is no waterproofing agent emulsion, only an adhesive emulsion.

[0116] Comparative Example 3

[0117] Other steps are the same as those in Example 1. The difference between this comparative example and Example 1 is that in the preparation method, in step 4), the dried chopped glass fibers are added to a 5% hydrofluoric acid solution.

[0118] Comparative Example 4

[0119] Other steps are the same as those in Example 1. The difference between this comparative example and Example 1 is that in the preparation method, in step 4), the dried chopped glass fibers are added to a 40% hydrofluoric acid solution.

[0120] Comparative Example 5

[0121] Other steps are the same as those in Example 1. The difference between this comparative example and Example 1 is that in the preparation method, in step 8), no anionic surfactant is added. After the waterproofing agent emulsion and the adhesive emulsion are mixed and stirred evenly and diluted to a mass concentration of 5%, the wet paper sheet in step 7) is impregnated.

[0122] Comparative Example 6

[0123] Other steps are the same as those in Example 1. The difference between this comparative example and Example 1 is that in the preparation method, in step 8), no anionic surfactant is added. After the waterproofing agent emulsion and the adhesive emulsion are mixed and stirred evenly and diluted to a mass concentration of 5%, the wet paper sheet in step 7) is sprayed.

[0124] Comparative Example 7

[0125] Other steps are the same as those in Example 1. The difference between this comparative example and Example 1 is that in the preparation method, in step 8), no anionic surfactant is added. After the waterproofing agent emulsion and the adhesive emulsion are mixed and stirred evenly and diluted to a mass concentration of 5%, the wet paper sheet in step 7) is curtain coated.

[0126] The filter materials prepared in each example and comparative example were tested. The test items and methods are as follows:

[0127] (1) Surface contact angle: According to the test standard: Tappi T 458CM - 2004;

[0128] (2) Filtration efficiency: According to the test standard: EN143:2006;

[0129] (3) Initial resistance: In accordance with the test standard: EN143:2006

[0130] (4) Dust holding capacity: In accordance with the test standard: ISO 5011:2020, the termination pressure drop is 600 Pa.

[0131] The test results are shown in Table 1.

[0132] Table 1 Test Results

[0133]

[0134] As can be seen from the above table, for the high moisture-resistant and high dust-holding high-efficiency air filtration materials prepared in Examples 1 to 3 of the present invention, with the increase in the concentration of hydrofluoric acid, the filtration efficiency, dust holding capacity and contact angle all increase accordingly, but the initial resistance also increases. It can be seen that the higher the concentration of hydrofluoric acid is not necessarily better, and various indicators need to be considered comprehensively.

[0135] Comparing Example 1 with Examples 4 and 5, it can be seen that with the increase in the mass concentration of the waterproofing agent emulsion and the adhesive emulsion, the filtration efficiency and dust holding capacity of the filtration material basically remain unchanged, but the contact angle and initial resistance increase slightly.

[0136] Comparing Examples 1 to 5 with Comparative Example 1, all indicators of the prepared high moisture-resistant and high dust-holding high-efficiency air filtration materials are better than those of Comparative Example 1. It can be seen that simple hydrofluoric acid etching will not form the target pits on the surface of glass fibers and will not achieve the purpose of further improving the filtration efficiency, dust holding capacity and contact angle. The reaction product formed by stearic acid, tetraethylenepentamine, fatty amine salt cationic surfactant and silane coupling agent in the examples can make hydrofluoric acid produce a good etching effect, thereby improving the filtration efficiency, dust holding capacity and contact angle.

[0137] Comparing Examples 1 to 5 with Comparative Example 1 and Comparative Example 2, the contact angles are better than those of Comparative Example 1 and Comparative Example 2. It can be seen that under the dual actions of using hydrofluoric acid to increase the surface roughness of fibers and adding a waterproofing agent in the examples, the moisture resistance of the filtration material can be greatly improved.

[0138] Comparing Example 1 with Comparative Example 2, the contact angle is better than that of Comparative Example 2. It can be seen that by adding a waterproofing agent emulsion in Example 1, the hydrophobicity can be further improved.

[0139] Comparing Example 1 with Comparative Example 3 and Comparative Example 4, the filtration efficiency, dust holding capacity and contact angle are all better than those of Comparative Example 3 and Comparative Example 4. It can be seen that the concentration of hydrofluoric acid in the examples needs to be within an appropriate range, and too high or too low will affect the etching effect, thereby affecting the filtration efficiency, dust holding capacity and contact angle.

[0140] Compared with Comparative Example 5, Comparative Example 6, and Comparative Example 7, the filtration efficiency, dust holding capacity, and contact angle of Example 1 are basically the same. However, the initial resistance of Comparative Example 5, Comparative Example 6, and Comparative Example 7 increases significantly. It can be seen that after forming a foam from the waterproofing agent emulsion and the adhesive emulsion and then attaching it to the filter medium in Example 1, the increase in the initial resistance can be avoided. In contrast, traditional impregnation, curtain coating, or spraying methods will all cause a significant increase in the initial resistance.

[0141] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a high-moisture-resistant and high-dust-holding-capacity glass fiber high-efficiency air filtration material, characterized in that, The steps include: (1) According to weight parts, 20 to 40 parts of stearic acid, 20 to 30 parts of tetraethylenepentamine, 15 to 25 parts of cationic surfactant, and 5 to 35 parts of silane coupling agent are mixed and heated to react, and after cooling, glacial acetic acid is added and reacted for several hours to obtain a protective film reaction product; (2) diluting the protective film reaction product of step (1) with water to a mass percentage concentration of 5 to 10% to obtain a protective film dilution solution; (3) impregnating the chopped glass fibers in the protective film dilution solution of step (2), and drying the impregnated chopped glass fibers to obtain chopped glass fibers with a protective film formed on the surface; (4) mixing the chopped glass fibers having the protective film formed on the surface in step (3) with a hydrofluoric acid solution, and introducing compressed air to partially etch the protective film; Then the solid and liquid are separated, and the surface of the solid phase is washed to neutrality with deionized water to obtain chopped glass fibers with partially etched surfaces; (5) fully mixing the chopped glass fibers and micro glass fibers with partially etched surfaces in step (4) with water to form a suspension; After solid-liquid separation and impurities are removed, dehydration is performed to form wet paper sheets; (6) Mixing and stirring the waterproofing agent emulsion, the adhesive emulsion and the anionic surfactant until foam is generated; then applying the foam to the surface of the wet paper sheet in step (5); and drying and curing the wet paper sheet with foam to obtain the air filter material.

2. The preparation method according to claim 1, characterized in that, Step (1) 20 to 40 parts of stearic acid, 20 to 30 parts of tetraethylenepentamine, 15 to 25 parts of a cationic surfactant, and 5 to 35 parts of a silane coupling agent are mixed, reacted at 140 to 160° C. for 1 to 1.5 hours, and then heated to 180 to 200° C. for 2 to 3 hours; after cooling to 40 to 60° C., glacial acetic acid is added and reacted for 2 to 3 hours to obtain a protective film reaction product.

3. The preparation method according to claim 1, characterized in that, The cationic surfactant in step (1) is a fatty amine salt.

4. The preparation method according to claim 1, characterized in that, Step (3) immerses the chopped glass fibers in the protective film dilution solution of step (2) for 10 to 20 minutes, and then dries the immersed chopped glass fibers at 100 to 120° C. for 5 to 10 minutes to obtain chopped glass fibers with a protective film formed on the surface.

5. The preparation method according to claim 1, characterized in that, Step (4) adding the chopped glass fibers with the protective film formed on the surface in step (3) into a 10-30 vol% hydrofluoric acid solution, and simultaneously introducing compressed air into the hydrofluoric acid solution for 10-20 minutes to partially etch the protective film.

6. The preparation method according to claim 1, characterized in that, The chopped glass fibers in step (3) have a diameter of 6 to 10 μm and a length of 10 to 12 mm. The microglass fibers in step (5) are composed of two or more glass fiber wools with different beating degrees and a beating degree of 19°SR to 59°SR.

7. The preparation method according to claim 1, characterized in that, Step (5): First, mix the surface-partially-etched chopped glass fibers and the micro glass fibers described in step (4) with water to prepare a suspension with a concentration of 0.1 - 0.5 wt%, and ultrasonically disperse it for 10 - 15 min; the mass ratio of the surface-partially-etched chopped glass fibers to the micro glass fibers is 1:9 - 3:7; then further dilute the dispersed suspension to a concentration of 0.02 - 0.05 wt%; after solid-liquid separation to remove impurities, vacuum dehydrate to form a wet paper sheet.

8. The preparation method according to claim 1, characterized in that, Step (6): Mix the waterproofing agent emulsion and the adhesive emulsion evenly and dilute to a mass concentration of 5 - 10%, then add an anionic surfactant and stir for 5 - 10 min to generate foam.

9. The preparation method according to claim 1, wherein, Step (6): Coat the foam onto the wet paper sheet described in step (5), with a coating thickness of 1 - 2 cm.

10. The preparation method according to claim 1, characterized in that, The drying in step (6) is specifically: drying at 80 - 100 °C for 0.5 - 3 min; the curing is specifically: curing at 150 - 180 °C for 3 - 6 min.

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