A nano-aramid fiber membrane / fiber glass composite material, its preparation method and application

Abstract

The present invention provides a nano-aramid fiber membrane / glass fiber composite material, belonging to the technical field of filter materials. The composite material includes alternately arranged nano-aramid fiber membranes and glass fiber filter papers. The total number of layers of the nano-aramid fiber membranes is 1 to 5 layers. The upper and lower surfaces of the nano-aramid fiber membrane / glass fiber composite material are glass fiber filter papers; the nano-aramid fiber membranes and the glass fiber filter papers are bonded by a cationic glue. The present invention uses a nano-aramid fiber membrane and a glass fiber filter paper to form a composite material for use as a water filtration material. The upper and lower surfaces of the composite material are glass fiber filter papers, which play a supporting role and increase the dirt-holding capacity of the composite material, while the nano-aramid fiber membranes between the layers can improve the filtration accuracy of the composite material.

Description

Technical Field

[0001] The present invention belongs to the technical field of filter materials, and particularly relates to a nano-aramid fiber membrane / fiberglass composite material, a preparation method thereof, and an application thereof. Background Art

[0002] During the production and power generation process of nuclear power plants, a large amount of radioactive impurities will be generated in the water circuit. These radioactive impurities pose a great danger to the safe production of nuclear power plants. Therefore, a nuclear-grade high-efficiency filter must be installed to filter and capture harmful particles in the water circuit. Since the diameter of radioactive impurities is very small (from micron level to nano level), the requirements for nuclear-grade high-efficiency filters are relatively high. At present, domestic nuclear-grade filter materials mainly use fiberglass as raw materials and are generally made by wet forming process. Fiberglass has the advantages of uniform fiber distribution, large dust capacity, small resistance, and high strength, and is an ideal water filtration material. However, the filtration accuracy of fiberglass filter materials is not high enough, and they only have good filtration performance for particles above 5μm, thus limiting their application.

[0003] Therefore, there is an urgent need for a filter material with higher filtration accuracy and less impact on filtration resistance. Summary of the Invention

[0004] The purpose of the present invention is to provide a nano-aramid fiber membrane / fiberglass composite material, a preparation method thereof, and an application thereof. The nano-aramid fiber membrane / fiberglass composite material provided by the present invention has higher filtration accuracy and smaller filtration resistance.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a nano-aramid fiber membrane / fiberglass composite material, comprising alternately arranged nano-aramid fiber membranes and fiberglass filter papers. The total number of layers of the nano-aramid fiber membranes is 1 - 5 layers, and the upper and lower surfaces of the nano-aramid fiber membrane / fiberglass composite material are fiberglass filter papers; the nano-aramid fiber membranes and the fiberglass filter papers are bonded by a cationic glue.

[0007] Preferably, the diameter of the nano-aramid fibers in each layer of the nano-aramid fiber membrane is independently 0.005 - 0.5μm, the gram weight of a single-layer nano-aramid fiber membrane is independently 5 - 10g / m 2 , and the pore diameter of a single-layer nano-aramid fiber membrane is independently 0.01 - 1μm.

[0008] Preferably, the diameter of the fiberglass in each layer of the fiberglass filter paper is independently 0.1 - 1μm, the gram weight of a single-layer fiberglass filter paper is independently 10 - 20g / m 2 , and the pore diameter of a single-layer fiberglass filter paper is independently 0.5 - 1μm.

[0009] The present invention provides a method for preparing the nano-aramid fiber membrane / fiberglass composite material described in the above technical solution, comprising: alternately stacking the nano-aramid fiber membrane and the fiberglass filter paper, and then performing sizing and hot pressing in sequence to obtain the nano-aramid fiber membrane / fiberglass composite material.

[0010] Preferably, the method for preparing the nano-aramid fiber membrane comprises the following steps:

[0011] (1) Mix the aramid fiber with the first dispersion liquid, and perform dispersion treatment to obtain nano-aramid fibers;

[0012] (2) Pulp the nano-aramid fibers obtained in the step (1) to obtain a nano-aramid fiber slurry;

[0013] (3) Film-form the nano-aramid fiber slurry obtained in the step (2) to obtain a nano-aramid fiber membrane.

[0014] Preferably, the first dispersion liquid in the step (1) comprises dimethyl sulfoxide, an alkali, and a solvent.

[0015] Preferably, the mass ratio of the aramid fiber to dimethyl sulfoxide and the alkali in the first dispersion liquid in the step (1) is 1:(500 - 1000):(5 - 25).

[0016] Preferably, the method for preparing the fiberglass filter paper comprises the following steps:

[0017] a. Mix the fiberglass with the second dispersion liquid, and perform dispersion treatment to obtain dispersed fiberglass; the pH value of the second dispersion liquid in the step a is 2 - 3;

[0018] b. Pulp the dispersed fiberglass obtained in the step a to obtain a fiberglass slurry;

[0019] c. Mold the fiberglass slurry obtained in the step b to obtain a fiberglass filter paper.

[0020] Preferably, the second dispersion liquid in the step a comprises water and an acid.

[0021] The present invention also provides the application of the nano-aramid fiber membrane / fiberglass composite material described in the above technical solution or the nano-aramid fiber membrane / fiberglass composite material prepared according to the preparation method described in the above technical solution as a filter medium.

[0022] The present invention provides a nano-aramid fiber membrane / fiberglass composite material, which comprises alternately arranged nano-aramid fiber membranes and fiberglass filter papers. The total number of layers of the nano-aramid fiber membranes is 1 to 5 layers, and the upper and lower surfaces of the nano-aramid fiber membrane / fiberglass composite material are fiberglass filter papers; the nano-aramid fiber membranes and the fiberglass filter papers are bonded by a cationic glue. The present invention uses a nano-aramid fiber membrane and a fiberglass filter paper to form a composite material. The upper and lower surfaces of the composite material are fiberglass filter papers, which play a supporting role and increase the dirt-holding capacity of the composite material, while the nano-aramid fiber membranes between the layers can improve the filtration accuracy of the composite material. The results of the examples show that the composite material provided by the present invention has a filtration efficiency of more than 85% for particles of 0.2 μm and above, and a dirt-holding capacity of more than 90 g / m 2 2 or more and has a relatively low filtration resistance. Detailed implementation manners

[0023] The present invention provides a nano-aramid fiber membrane / fiberglass composite material, which comprises alternately arranged nano-aramid fiber membranes and fiberglass filter papers. The total number of layers of the nano-aramid fiber membranes is 1 to 5 layers, and the upper and lower surfaces of the nano-aramid fiber membrane / fiberglass composite material are fiberglass filter papers; the nano-aramid fiber membranes and the fiberglass filter papers are bonded by a cationic glue.

[0024] In the present invention, the total number of layers of the nano-aramid fiber membranes is 1 to 5 layers, and specifically, it can be 1, 2, 3, 4 or 5 layers in the examples. The present invention limits the number of layers of the nano-aramid fiber membranes within the above range, which can improve the filtration accuracy of the composite material and ensure that the composite material has a relatively low filtration resistance.

[0025] In the present invention, the upper and lower surfaces of the nano-aramid fiber membrane / fiberglass composite material are fiberglass filter papers. The present invention controls the upper and lower surfaces of the composite material to be fiberglass filter papers, which can play a supporting role and increase the dirt-holding capacity of the composite material.

[0026] In the present invention, the nano-aramid fiber membranes and the fiberglass filter papers are bonded by a cationic glue. In the present invention, the cationic glue preferably comprises one or more of polyamide epichlorohydrin, polyacrylamide and polyurethane. In the present invention, the cationic glue not only plays a bonding role, but also can form a cation adsorption filtration channel between the composite materials, and utilizes the adsorption property of cations to improve the filtration efficiency of the composite material. In the present invention, the sizing amount of the cationic glue is preferably 5 to 10% of the total mass of the composite filter material, and more preferably 6 to 8%. The present invention limits the sizing amount of the cationic glue within the above range, which can enable the composite filter material to have good stiffness and hardness, excellent bonding property between layers, and will not overly block the pores between the fibers, and further improve the filtration effect of the composite material by utilizing the cation adsorption property.

[0027] In the present invention, the diameter of the nano-aramid fibers in each layer of the nano-aramid fiber membrane is independently preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.4 μm, and most preferably 0.01 to 0.1 μm; the length of the nano-aramid fibers is independently preferably 30 to 300 μm, more preferably 100 to 200 μm; the grammage of the single-layer nano-aramid fiber membrane is independently preferably 5 to 10 g / m 2 , more preferably 6 to 8 g / m 2 ; the pore diameter of the single-layer nano-aramid fiber membrane is independently preferably 0.01 to 1 μm, more preferably 0.05 to 0.5 μm. By limiting the diameter of the nano-aramid fibers, the grammage of the single-layer nano-aramid fiber membrane, and the pore diameter in each layer of the nano-aramid fiber membrane within the above ranges, the nano-aramid membrane can have higher filtration accuracy and lower filtration resistance.

[0028] In the present invention, the diameter of the glass fibers in each layer of the glass fiber filter paper is independently preferably 0.1 to 1 μm, more preferably 0.2 to 0.8 μm; the length of the glass fibers is independently preferably 30 to 300 μm, more preferably 100 to 200 μm; the grammage of the single-layer glass fiber filter paper is independently preferably 10 to 20 g / m 2 , more preferably 12 to 18 g / m 2 ; the pore diameter of the single-layer glass fiber filter paper is independently preferably 0.5 to 1 μm, more preferably 0.6 to 0.8 μm. By limiting the diameter of the glass fibers, the grammage of the single-layer glass fiber filter paper, and the pore diameter in each layer of the glass fiber filter paper within the above ranges, the glass fiber filter paper can have a higher dirt holding capacity.

[0029] The present invention provides a method for preparing the nano-aramid fiber membrane / glass fiber composite material according to the above technical solution, including: alternately stacking the nano-aramid fiber membrane and the glass fiber filter paper, and then performing sizing and hot pressing in sequence to obtain the nano-aramid fiber membrane / glass fiber composite material.

[0030] The present invention has no special limitation on the sizing operation, and the sizing technical solutions well-known to those skilled in the art can be adopted.

[0031] In the present invention, the temperature of the hot pressing is preferably 90 to 100 °C, more preferably 90 to 95 °C; the time of the hot pressing is preferably 10 to 30 min, more preferably 20 to 30 min. In the present invention, the hot pressing is used for drying and making the surface of the composite material flat.

[0032] In the present invention, the method for preparing the nano-aramid fiber membrane preferably includes the following steps:

[0033] (1) Mix the aramid fiber with Dispersion Liquid 1 and perform dispersion treatment to obtain nano aramid fiber;

[0034] (2) Pulp the nano aramid fiber obtained in step (1) above to obtain nano aramid fiber slurry;

[0035] (3) Film the nano aramid fiber slurry obtained in step (2) above to obtain nano aramid fiber film.

[0036] Unless otherwise specified, the present invention does not have special limitations on the sources of the various raw materials, and commercially available products well-known to those skilled in the art can be used.

[0037] In the present invention, the aramid fiber is mixed with Dispersion Liquid 1 and subjected to dispersion treatment to obtain nano aramid fiber.

[0038] In the present invention, the diameter of the aramid fiber is preferably 0.1 - 10 μm, more preferably 1 - 8 μm; the length of the aramid fiber is preferably 30 - 300 μm, more preferably 50 - 200 μm. The present invention does not have special limitations on the source of the aramid fiber, and commercially available products with lengths and diameters within the above ranges well-known to those skilled in the art can be used. In the present invention, the aramid fiber is preferably the aramid fiber produced by DuPont.

[0039] In the present invention, the aramid fiber is preferably dried before use; the drying temperature is preferably 120 - 160 °C, more preferably 130 - 150 °C; the drying time is preferably 12 - 36 h, more preferably 24 - 30 h. In the present invention, the drying can remove the moisture in the aramid fiber and avoid affecting the weighing.

[0040] In the present invention, Dispersion Liquid 1 preferably includes dimethyl sulfoxide, alkali, and solvent.

[0041] In the present invention, as a dispersion solution, during the dispersion treatment, the hydrogen in the amide group of the aramid fiber is taken away by the alkali and deprotonated to generate a negatively charged polyanion. In the initial stage of the deprotonation process, negative charges gradually accumulate on the aramid fiber molecular chain, and the generated electrostatic repulsion gradually splits the macroscopic aramid fiber into microfiber bundles. As the degree of deprotonation increases, the electrostatic repulsion between the polymer chains also gradually increases, providing the energy required to break the intermolecular hydrogen bonds between the polymer chains, and finally obtaining aramid fibers with a high aspect ratio. The aramid fibers can be stably dispersed in dimethyl sulfoxide under the balance of electrostatic repulsion, van der Waals forces, and π-π stacking.

[0042] In the present invention, the base is preferably a strong base, more preferably a metal hydroxide, such as one or more of an alkali metal hydroxide and an alkaline earth metal hydroxide, and in the embodiment of the present invention, it can be specifically one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide and barium hydroxide. In the present invention, the base acts as a dispersing aid, mainly together with dimethyl sulfoxide, to accelerate the dispersion of aramid, deprotonate aramid, that is, quickly capture hydrogen on the aramid molecule, so that polyanions are formed on the surface of aramid.

[0043] In the present invention, the solvent preferably includes one or more of methanol, ethanol and water. In the present invention, the methanol, ethanol and water can help the dispersion liquid to take away the protons of the aramid fiber faster, accelerate the deprotonation process, and accelerate the dispersion rate of the aramid fiber.

[0044] In the present invention, the mass ratio of the aramid fiber to the dimethyl sulfoxide and the alkali in the dispersion one is preferably 1: (500-1000): (5-25), more preferably 1: (500-800): (10-20). In the present invention, the volume ratio of the mass of the aramid fiber to the solvent in the dispersion one is preferably 1 g: (30-50) mL, more preferably 1 g: (35-45) mL. The present invention limits the ratio of the aramid fiber to the dimethyl sulfoxide, the alkali and the solvent in the dispersion one within the above range, so that the aramid fiber can be fully dispersed.

[0045] In the present invention, the time of the dispersion treatment is preferably 5 to 150 minutes, more preferably 10 to 120 minutes, and most preferably 30 to 60 minutes. In the present invention, the dispersion treatment is preferably carried out under stirring conditions, and the stirring rate is preferably 800 to 1200 rpm, more preferably 1000 rpm. The present invention limits the time of the dispersion treatment and the stirring rate to the above range, so that the dispersed aramid fibers can maintain the fiber morphology and have a suitable diameter and length, further improving the filtration accuracy of the composite material and reducing the filtration resistance.

[0046] After the dispersion treatment is completed, the present invention preferably washes and then filters the product of the dispersion treatment to obtain nano-aramid fibers.

[0047] The present invention has no special limitation on the washing and filtering operations, and the washing and filtering technical solutions well known to those skilled in the art can be adopted.

[0048] After obtaining the nano-aramid fibers, the present invention pulps the nano-aramid fibers to obtain nano-aramid fiber slurry.

[0049] In the present invention, the pulping is preferably carried out by mixing nano-aramid fibers with water; the mass ratio of the nano-aramid fibers to water is preferably 1:(50 - 200), more preferably 1:(100 - 150). By limiting the mass ratio of the nano-aramid fibers to water within the above range, the nano-aramid fibers can be more fully dispersed, which is beneficial for subsequent processing and forming.

[0050] In the present invention, the mixing of the nano-aramid fibers and water is preferably carried out under high-speed mechanical stirring; the rotation speed of the high-speed mechanical stirring is preferably 1000 - 20000 revolutions per minute, more preferably 2000 - 15000 revolutions per minute; the time of the high-speed mechanical stirring is preferably 1 - 30 minutes, more preferably 5 - 25 minutes. By limiting the rotation speed and time of the high-speed mechanical stirring within the above range, the nano-aramid fibers can be more fully dispersed.

[0051] After obtaining the nano-aramid fiber slurry, the present invention forms the nano-aramid fiber slurry into a film to obtain a nano-aramid fiber film.

[0052] In the present invention, the method of film forming is preferably: subjecting the nano-aramid fiber slurry to papermaking, first hot pressing and cooling in sequence to obtain a nano-aramid fiber film.

[0053] The present invention has no special limitation on the operation of the papermaking, and the technical solutions of papermaking well-known to those skilled in the art can be adopted.

[0054] In the present invention, the temperature of the first hot pressing is preferably 90 - 100 °C, more preferably 95 °C; the time of the first hot pressing is preferably 10 - 40 minutes, more preferably 15 minutes; the pressure of the first hot pressing is preferably 1 - 5 kPa, more preferably 2 - 4 kPa. In the present invention, the first hot pressing is used for drying and making the film surface flat. In the present invention, the "first" in the first hot pressing and the "second" in the subsequent second hot pressing are only used to distinguish the two hot pressing processes, and there is no chronological order.

[0055] In the present invention, the preparation method of the glass fiber filter paper preferably includes the following steps:

[0056] a. Mix the glass fibers with the dispersion liquid II and carry out dispersion treatment to obtain dispersed glass fibers; the pH value of the dispersion liquid II is 2 - 3;

[0057] b. Pulp the dispersed glass fibers obtained in step a to obtain a glass fiber slurry;

[0058] c. Form the glass fiber slurry obtained in step b to obtain a glass fiber filter paper.

[0059] In the present invention, glass fibers are mixed with dispersion liquid II and subjected to dispersion treatment to obtain dispersed glass fibers.

[0060] In the present invention, the diameter of the glass fibers is preferably 0.1 - 20 μm, more preferably 1 - 15 μm; the length of the glass fibers is preferably 30 - 300 μm, more preferably 100 - 200 μm. There are no special limitations on the source of the glass fibers in the present invention, and commercially available products with diameters and lengths within the above ranges well-known to those skilled in the art can be used. In the present invention, the glass fibers are preferably those produced by Dazhou Pufei New Materials Co., Ltd.

[0061] In the present invention, the glass fibers are preferably dried before use; the drying temperature is preferably 120 - 160 °C, more preferably 130 - 150 °C; the drying time is preferably 12 - 36 h, more preferably 24 - 30 h. In the present invention, the drying can remove the moisture in the glass fibers and avoid affecting the weighing.

[0062] In the present invention, the pH value of dispersion liquid II is 2 - 3. By limiting the pH value of dispersion liquid II within the above range in the present invention, the glass fibers can be fully dispersed and have a smaller diameter.

[0063] In the present invention, dispersion liquid II preferably includes water and an acid. In the present invention, the acid is preferably one or more of sulfuric acid, hydrochloric acid, and nitric acid. There are no special limitations on the concentration and dosage of the acid in the present invention, as long as the pH value of dispersion liquid II is within the above range.

[0064] In the present invention, the mass ratio of the glass fibers to dispersion liquid II is preferably 1:(100 - 200), more preferably 1:(120 - 180). By limiting the mass ratio of the glass fibers to dispersion liquid II within the above range in the present invention, the glass fibers can be more fully dispersed.

[0065] In the present invention, the time for the dispersion treatment is preferably 5 - 150 min, more preferably 10 - 120 min, and most preferably 30 - 60 min. In the present invention, the dispersion treatment is preferably carried out under stirring conditions, and the stirring rate is preferably 800 - 1200 rpm, more preferably 1000 rpm. By limiting the time for the dispersion treatment and the stirring rate within the above ranges in the present invention, the dispersed glass fibers can have appropriate diameters and lengths, further improving the filtration accuracy of the composite material and increasing the dirt holding capacity.

[0066] After the dispersion treatment is completed, in the present invention, the product of the dispersion treatment is preferably washed and then filtered to obtain dispersed glass fibers.

[0067] The present invention has no special limitation on the operations of the washing and filtration, and the technical solutions of washing and filtration well-known to those skilled in the art can be adopted.

[0068] After obtaining the dispersed glass fibers, the present invention pulps the dispersed glass fibers to obtain a glass fiber slurry.

[0069] In the present invention, the pulping is preferably to mix the dispersed glass fibers and water for pulping; the mass ratio of the dispersed glass fibers to water is preferably 1:(90 - 110), more preferably 1:100. The present invention limits the mass ratio of the dispersed glass fibers to water within the above range, which can make the dispersed glass fibers more fully dispersed and is beneficial to subsequent processing and forming.

[0070] In the present invention, the mixing of the dispersed glass fibers and water is preferably carried out under high-speed mechanical stirring; the rotation speed of the high-speed mechanical stirring is preferably 1000 - 20000 revolutions per minute, more preferably 2000 - 15000 revolutions per minute; the time of the high-speed mechanical stirring is preferably 1 - 30 minutes, more preferably 5 - 25 minutes. The present invention limits the rotation speed and time of the high-speed mechanical stirring within the above range, which can make the glass fibers more fully dispersed.

[0071] After obtaining the glass fiber slurry, the present invention forms the glass fiber slurry to obtain a glass fiber filter paper.

[0072] In the present invention, the method of forming is preferably: subjecting the glass fiber slurry to papermaking, second hot pressing and cooling in sequence to obtain a glass fiber filter paper.

[0073] The present invention has no special limitation on the operation of the papermaking, and the technical solutions of papermaking well-known to those skilled in the art can be adopted.

[0074] In the present invention, the temperature of the second hot pressing is preferably 80 - 95 °C, more preferably 85 °C; the time of the second hot pressing is preferably 20 - 40 minutes, more preferably 30 minutes; the pressure of the second hot pressing is preferably 1 - 5 kPa, more preferably 2 - 4 kPa. In the present invention, the second hot pressing is used for drying and making the paper surface flat.

[0075] The present invention also provides the application of the nano-aramid fiber membrane / glass fiber composite material described in the above technical solution or the nano-aramid fiber membrane / glass fiber composite material prepared according to the preparation method described in the above technical solution as a filter medium.

[0076] The present invention has no special limitation on the operation of the application of the nano-aramid fiber membrane / glass fiber composite material as a filter medium, and the technical solutions of the application of materials well-known to those skilled in the art as filter media can be adopted.

[0077] The technical solutions of the present invention will be clearly and completely described below 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 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.

[0078] Example 1

[0079] The nano-aramid fiber membrane / fiberglass composite material of this embodiment is composed of alternately arranged nano-aramid fiber membranes and fiberglass filter papers. The total number of layers of the nano-aramid fiber membranes is 2 layers. The upper and lower surfaces of the nano-aramid fiber membrane / fiberglass composite material are fiberglass filter papers, that is, the composite material is, from bottom to top, fiberglass filter paper, nano-aramid fiber membrane, fiberglass filter paper, nano-aramid fiber membrane, and fiberglass filter paper in sequence; the nano-aramid fiber membrane and the fiberglass filter paper are bonded by cationic glue polyamide epichlorohydrin.

[0080] The preparation method is as follows:

[0081] (1) Dry the aramid fibers (diameter 0.1 - 10 μm, length 30 - 300 μm) at 150 °C for 24 h. Weigh 0.5 g of the dried aramid fibers and add them to the first dispersion liquid. The first dispersion liquid is composed of 2.5 g of KOH, 10 mL of ethanol, 10 mL of deionized water, and 250 mL of dimethyl sulfoxide (the mass ratio of aramid fibers to dimethyl sulfoxide and alkali is 1:550:5, and the mass ratio of aramid fibers to the total volume of ethanol and deionized water is 1 g:40 mL). Stir at 1000 rpm for 30 min, and then wash and filter three times with deionized water to obtain nano-aramid fibers.

[0082] (2) Mix the nano-aramid fibers and water according to a mass ratio of 1:100, and obtain a nano-aramid fiber slurry after high-speed mechanical stirring at 15000 rpm for 20 min.

[0083] (3) Use a paper-making machine to make a nano-aramid fiber wet film with a diameter of 21.5 cm from the nano-aramid fiber slurry, and hot press it at 95 °C for 30 min to obtain a nano-aramid fiber membrane (the diameter of the nano-aramid fibers in the nano-aramid fiber membrane is 0.005 - 0.05 μm, and the grammage of the nano-aramid fiber membrane is 7 g / m 2 , and the pore diameter is 0.05 - 0.5 μm).

[0084] (4) Dry the glass fibers (with a diameter of 0.1 - 10 μm and a length of 30 - 300 μm) at 150 °C for 24 h. Weigh 1 g of the dried glass fibers and add them to the second dispersion liquid. The second dispersion liquid consists of deionized water and sulfuric acid, and the pH value of the second dispersion liquid is 2 (the mass ratio of glass fibers to the second dispersion liquid is 1:150). Stir at 1000 rpm for 30 min, and then wash and filter three times with deionized water to obtain the dispersed glass fibers;

[0085] (5) Mix the dispersed glass fibers and water according to a mass ratio of 1:100, and obtain a glass fiber slurry after high-speed mechanical stirring at 15000 rpm for 20 min;

[0086] (6) Use a paper-making machine to make a filter paper with a diameter of 21.5 cm from the glass fiber slurry, and hot-press it at 95 °C and 3 kPa for 30 min to obtain a glass fiber filter paper (the diameter of the glass fibers in the glass fiber filter paper is 0.1 - 1 μm, and the grammage of the glass fiber filter paper is 15 g / m 2 , and the pore size is 0.5 - 1 μm);

[0087] (7) Alternately stack 3 glass fiber filter papers and 2 nano-aramid fiber membranes, and apply sizing (the sizing solution is an aqueous solution of polyamide epichlorohydrin with a solid content of 2%). The sizing amount is 8%, and then hot-press at 95 °C and 3 kPa for 30 min, and cool to obtain a composite material.

[0088] Example 2

[0089] Replace the total number of layers of nano-aramid fiber membranes in the composite material of Example 1 with 4 layers, and replace the number of layers of glass fiber filter papers with 5 layers. Other parameters and preparation methods are the same as those in Example 1.

[0090] Example 3

[0091] Replace the total number of layers of nano-aramid fiber membranes in the composite material of Example 1 with 1 layer, and replace the number of layers of glass fiber filter papers with 2 layers. Other parameters and preparation methods are the same as those in Example 1.

[0092] Test the filtration efficiency, clean differential pressure, and dirt-holding capacity of the composite materials of Examples 1 - 3 for particles with different particle sizes, and the results are listed in Table 1.

[0093] Filtration efficiency, clean differential pressure, and dirt-holding capacity of the composite materials of Examples 1 - 3 for particles with different particle sizes

[0094]

[0095]

[0096] As can be seen from Table 1, the composite material prepared by the present invention has a high filtration effect on particles of 0.2 μm and above, with high filtration accuracy, low filtration resistance, and a high dirt-holding capacity.

[0097] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A nano-aramid fiber membrane / fiberglass composite material, comprising alternately arranged nano-aramid fiber membranes and fiberglass filter papers. The total number of layers of the nano-aramid fiber membranes is 2 to 5 layers, and the upper and lower surfaces of the nano-aramid fiber membrane / fiberglass composite material are fiberglass filter papers; the nano-aramid fiber membranes and the fiberglass filter papers are bonded by a cationic glue; The diameter of the nano-aramid fibers in each layer of the nano-aramid fiber membrane is independently 0.005 to 0.5 μm, and the grammage of a single layer of the nano-aramid fiber membrane is independently 5 to 10 g / m 2 , and the pore size of a single layer of the nano-aramid fiber membrane is independently 0.01 to 1 μm; the diameter of the glass fibers in each layer of the glass fiber filter paper is independently 0.1 to 1 μm, and the grammage of a single layer of the glass fiber filter paper is independently 10 to 20 g / m 2 , and the pore size of a single layer of the glass fiber filter paper is independently 0.5 to 1 μm.

2. The preparation method of the nano-aramid fiber membrane / fiberglass composite material according to claim 1, comprising: After alternately stacking the nano-aramid fiber membranes and the fiberglass filter papers, sizing and hot pressing are carried out in sequence to obtain the nano-aramid fiber membrane / fiberglass composite material.

3. The preparation method according to claim 2, wherein The preparation method of the nano-aramid fiber membrane comprises the following steps: (1) Mix aramid fibers with dispersion liquid I, and carry out dispersion treatment to obtain nano-aramid fibers; (2) Pulp the nano-aramid fibers obtained in step (1) to obtain a nano-aramid fiber slurry; (3) Form the nano-aramid fiber slurry obtained in step (2) into a film to obtain a nano-aramid fiber membrane.

4. The preparation method according to claim 3, characterized in that, The dispersion liquid I in step (1) comprises dimethyl sulfoxide, an alkali, and a solvent.

5. The preparation method of the nano-aramid fiber membrane / fiberglass composite filter material according to claim 4, wherein, The mass ratio of the aramid fibers to dimethyl sulfoxide and the alkali in the dispersion liquid I in step (1) is 1:(500 - 1000):(5 - 25).

6. The preparation method according to claim 2, characterized in that, The preparation method of the fiberglass filter paper comprises the following steps: a. Mix glass fibers with dispersion liquid II, and carry out dispersion treatment to obtain dispersed glass fibers; the pH value of the dispersion liquid II in step a is 2 to 3; b. Pulp the dispersed glass fibers obtained in step a to obtain a glass fiber slurry; c. Shape the glass fiber slurry obtained in step b to obtain a fiberglass filter paper.

7. The preparation method according to claim 6, characterized in that, The dispersion liquid II in step a comprises water and an acid.

8. The application of the nano-aramid fiber membrane / fiberglass composite material according to claim 1 or the nano-aramid fiber membrane / fiberglass composite material prepared by the preparation method according to any one of claims 2 to 7 as a filter medium.

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