Double-layer air filter paper with high interface adhesive force as well as preparation method and application of double-layer air filter paper

Abstract

The invention discloses double-layer air filter paper with high interface adhesion as well as a preparation method and application of the double-layer air filter paper. The air filter paper is used as a paper base, nanofiber is deposited on the surface of the paper base through electrostatic spinning to form a fiber membrane, and then drying and thermal crosslinking are performed to obtain the air filter paper. A spinning solution adopted in the electrostatic spinning is a spinning solution obtained by dissolving polyurethane in a DMF / THF mixed solvent, and a silane coupling agent is added into the spinning solution for blending. The interface adhesive force between the fiber membrane and the paper base is improved by controlling the type, the adding amount, the thermal crosslinking temperature and the thermal crosslinking time of the added silane coupling agent, the diameter of the fiber is reduced to the nanoscale by regulating and controlling the parameters of the spinning solution, the composite stability of the double-layer air filter paper is guaranteed, and meanwhile the filtering performance of the air filter base paper is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of air filter paper, and particularly relates to a double-layer air filter paper with high interfacial adhesion and a preparation method thereof. Background Art

[0002] The engine, as the "heart" of an automobile, provides continuous mechanical power for the automobile. As an important component in the intake system of an automobile engine, the air filter reduces the wear of engine components by filtering particles in the air. Therefore, its filtration quality directly affects the stability and reliability of engine operation. Air filters are usually made of plant fibers, but the filtration accuracy of plant fiber-based air filter paper is insufficient. By introducing nanofibers and combining them with paper-based filter paper, among which the electrospun fiber membrane is a porous material with a micro-nano scale diameter, small pore size, and good air permeability. Due to its inherent fine porous structure, it can intercept and filter particles in the air, so it has great application prospects in the field of air filtration. Combining it with paper-based air filter paper can improve its filtration performance. However, the weak interfacial adhesion between the nanofiber membrane and the substrate causes the nanofiber membrane to fall off during the long-term use of the multi-layer air filter paper, which in turn leads to a decrease in the filtration performance of the multi-layer air filter paper and ultimately results in the failure of the entire filtration system. However, most scholars have studied the modification of fibers and lack research on the interfacial adhesion between nanofibers and paper-based fibers.

[0003] Zhao from Soochow University thermally pressed PVA / ethylene propylene parallel non-woven fabric to obtain a PVA fiber membrane with filtration performance (thickness 32.7μm, air permeability 12.57mm / s, filtration efficiency of PM0.3 99.99%, gas resistance 1435.2Pa, interfacial adhesion only 0.1N / cm), but its interfacial adhesion is too small and the filtration resistance is too large; in order to improve the interfacial adhesion while reducing the gas resistance, Guo from Northeastern University controlled the temperature of TPU to adhere to the PET non-woven fabric substrate and PET nanofibers during the solidification process to enhance the adhesion, and prepared a PET / TPU composite filter membrane (at a flow rate of 5cm / s, the filtration resistance is 28.96Pa, the filtration efficiency of PM0.3 particulate matter is less than 60%, and the interfacial adhesion reaches 1.385N / cm). The above researchers cannot balance the interfacial adhesion, air filtration resistance, and filtration efficiency.

[0004] Therefore, there is an urgent need in the art for a method for producing a double-layer air filter paper with excellent adhesion strength, balanced filtration resistance and filtration efficiency, and capable of large-scale production. Summary of the Invention

[0005] To overcome the deficiencies of the above-mentioned existing technologies, the present invention provides a method for preparing a double-layer air filter paper with high interfacial adhesion, which improves the filtration performance of the air filter base paper while ensuring the composite stability of the double-layer air filter paper.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] A method for preparing a double-layer air filter paper with high interfacial adhesion is obtained by using an air filter paper as a paper base, depositing nanofibers on the surface of the paper base through electrospinning to form a fiber membrane, and then drying and thermally cross-linking. The spinning solution used in the electrospinning is a spinning solution obtained by dissolving polyurethane in a mixed solvent of DMF / THF, and a silane coupling agent is added to the spinning solution for blending.

[0008] Further, the mass concentration of polyurethane in the spinning solution is 15-20 wt%.

[0009] Further, the mass concentration of the silane coupling agent added to the spinning solution is 2-6 wt%, and the type of the silane coupling agent is one of A151, A171, A172, KH-550, KH-560, KH-570, KH792, and DL602.

[0010] Further, the temperature of the drying and thermal cross-linking is 100-150 °C.

[0011] Further, the time of the drying and thermal cross-linking is 1-3 h.

[0012] Further, the thickness of the fiber membrane formed on the surface of the paper base is 2-8 μm.

[0013] The double-layer air filter paper with high interfacial adhesion prepared by the preparation method of the present invention is also within the protection scope of the present invention.

[0014] The application of the double-layer air filter paper with high interfacial adhesion prepared by the preparation method of the present invention in the preparation of an air filter for an automobile engine.

[0015] The interfacial adhesion of the double-layer air filter paper with high interfacial adhesion is 0.28-2.15 N / 12.7 mm.

[0016] The air filtration resistance of the double-layer air filter paper with high interfacial adhesion is 104.2-124.7 Pa under the condition that the air flow rate is 32 L / min.

[0017] The filtration efficiency of the double-layer air filter paper with high interfacial adhesion for PM0.3 particles is 50.94-64.04% under the condition that the air flow rate is 32 L / min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) Compared with other air filter papers, the present invention improves the interfacial adhesion force between the polyurethane fiber membrane and the paper base by regulating the type, addition amount, thermal cross-linking temperature and time of the silane coupling agent, and reduces the fiber diameter to the nanometer level by regulating the parameters of the spinning solution, ensuring the composite stability of the double-layer air filter paper and improving the filtration performance of the air filter base paper at the same time.

[0020] (2) The double-layer air filter paper with high interfacial adhesion force prepared by the present invention has good interfacial adhesion force (0.28 - 2.15 N / 12.7 mm).

[0021] (3) The double-layer air filter paper with high interfacial adhesion force prepared by the present invention has an air filtration resistance of 104.2 - 124.7 Pa under the condition of an air flow rate of 32 L / min.

[0022] (4) The double-layer air filter paper with high interfacial adhesion force prepared by the present invention enhances the filtration performance of PM 0.3 on the basis of the original paper base, and the air filtration efficiency of PM0.3 reaches 64.04%. Detailed implementation manners

[0023] The present invention will be further described below in conjunction with embodiments, but it should not be construed as a limitation of the present invention. Without departing from the spirit and essence of the present invention, simple modifications or substitutions made to the methods, steps or adjustments of the present invention all fall within the scope of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well-known to those skilled in the art.

[0024] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field. Unless otherwise specified, the reagents and materials used in the following embodiments are all commercially available.

[0025] Embodiment 1

[0026] A preparation method of a double-layer air filter paper with high interfacial adhesion force, and the specific preparation method is as follows:

[0027] S1. Dissolve polyurethane in a DMF / THF mixed solvent to prepare a homogeneous spinning solution with a mass concentration of 20 wt%. The N,N-dimethylformamide (DMF) / tetrahydrofuran (THF) in the mixed solvent is 9 / 1 (v / v). Then, add silane coupling agent KH-560 with concentrations of 2 wt%, 4 wt% and 6 wt% (the mass concentration of the silane coupling agent in the spinning solution) respectively for blending and dissolving to prepare spinning solutions with different silane coupling agent concentrations.

[0028] S2. Stir the mixed solution in step S1 at room temperature for 2.5 h to completely dissolve it into a uniform and transparent spinning solution.

[0029] S3. Pump the spinning solution in step S2 into a syringe with a medical specification of 10 mL, replace the needle with a special stainless-steel needle for electrospinning with a model of 21G, and clamp it on the fixture of the electrospinning machine.

[0030] S4. Wind the metal aluminum foil around the receiving metal roller, then wind the commercial air filter paper as the paper base around the surface of the metal aluminum foil, and fix it with paper-based tape.

[0031] S5. Adjust the injection speed of the spinning solution of the electrospinning machine to 0.25 mm / min, the injection stroke to 10 mm, the receiving distance to 200 mm, the translation speed to 50 mm / min, the translation stroke to 200 mm, and the rotation speed of the receiving roller to 100 rpm / min.

[0032] S6. Electrospin nanofibers and deposit them on the surface of the paper base to form a fiber membrane.

[0033] S7. After the spinning is completed, put the double-layer air filter paper into an oven at 150 °C and dry it for 3 h.

[0034] Measure the bonding strength of the double-layer air filter paper prepared in this example under normal temperature and pressure using a universal material tensile machine and the 180° peeling method. Select a suitable fixture type, clamp the 3M tape with the upper fixture, fix the sample substrate with the lower fixture, with a stretching rate of 300 mm / min, and test the change of force with displacement during the tensile test.

[0035] Example 2

[0036] A preparation method of a double-layer air filter paper with high interfacial adhesion force, and the specific preparation method is as follows:

[0037] S1. Dissolve polyurethane in a DMF / THF mixed solvent to prepare a uniform spinning solution with a mass concentration of 20 wt%, and then add silane coupling agent KH-560 (the mass concentration of the silane coupling agent in the spinning solution is 4 wt%) for co-blending and dissolving. The DMF / THF in the mixed solvent is 9 / 1 (v / v).

[0038] S2. Stir the mixed solution in step S1 at room temperature for 2.5 h to completely dissolve it into a uniform and transparent spinning solution.

[0039] S3. Pump the spinning solution in step S2 into a syringe with a medical specification of 10 mL, replace the needle with a special stainless-steel needle for electrospinning with a model of 21G, and clamp it on the fixture of the spinning machine.

[0040] S4. Wind the metallic aluminum foil around the receiving metal roller, then wind the commercial air filter paper as the paper base around the surface of the metallic aluminum foil, and fix it with a paper-based tape.

[0041] S6. Adjust the spinning solution injection speed of the electrospinning machine to 0.25 mm / min, the injection stroke to 10 mm, the receiving distance to 200 mm, the translation speed to 50 mm / min, the translation stroke to 200 mm, and the receiving roller rotation speed to 100 rpm / min. Electrospin nanofibers and deposit them on the surface of the paper base to form a fiber membrane.

[0042] S7. After the spinning is completed, put the three samples of the double-layer air filter paper into an oven at 100 °C, 130 °C, and 150 °C respectively for drying for 3 h.

[0043] Measure the bonding strength of the double-layer air filter paper prepared in this example at normal temperature and pressure using a universal material testing machine and the 180° peeling method. Select a suitable fixture type, clamp the 3M tape with the upper fixture, fix the sample substrate with the lower fixture, and the stretching rate is 300 mm / min. Measure the change of force with displacement during the tensile test.

[0044] Example 3

[0045] A preparation method of a double-layer air filter paper with high interfacial adhesion force is as follows:

[0046] S1. Dissolve polyurethane in a DMF / THF mixed solvent to prepare a homogeneous spinning solution with a mass concentration of 20 wt%, and then add a silane coupling agent KH-560 (the mass concentration of the silane coupling agent in the spinning solution is 4 wt%) for co-blending and dissolving. The DMF / THF in the mixed solvent is 9 / 1 (v / v).

[0047] S2. Stir the mixed solution in step S1 at room temperature for 2.5 h to completely dissolve it into a homogeneous and transparent spinning solution.

[0048] S3. Pump the spinning solution in step S2 into a syringe with a medical specification of 10 mL, replace it with a special stainless-steel needle for electrospinning with a model of 21G, and clamp it on the fixture of the electrospinning machine.

[0049] S4. Wind the metallic aluminum foil around the receiving metal roller, then wind the commercial air filter paper as the paper base around the surface of the metallic aluminum foil, and fix it with a paper-based tape.

[0050] S6. Adjust the spinning solution injection speed of the electrospinning machine to 0.25 mm / min, the injection stroke to 10 mm, the receiving distance to 200 mm, the translation speed to 50 mm / min, the translation stroke to 200 mm, and the receiving roller rotation speed to 100 rpm / min. Electrospin nanofibers and deposit them on the surface of the paper base to form a fiber membrane.

[0051]

[0051] After the spinning is completed, three samples of the double-layer air filter paper are respectively placed in an oven at 150 °C for drying for 1 h, 2 h, and 3 h.

[0052]

[0052] The double-layer air filter paper prepared in this example is used at normal temperature and pressure. The universal material tensile machine is used and the 180° peeling method is used to peel it to measure its bonding strength. Select a suitable fixture type. The upper fixture clamps the 3M tape, the lower fixture fixes the sample substrate, the stretching rate is 300 mm / min, and the change of force with displacement during the tensile test is measured.

[0053] Example 4

[0054]

[0054] A preparation method of a double-layer air filter paper with high interfacial adhesion force is as follows:

[0055]

[0055] Dissolve polyurethane in a DMF / THF mixed solvent to prepare uniform spinning solutions with mass concentrations of 17 wt%, 16 wt%, and 15 wt% respectively. Then add silane coupling agent KH-560 (the mass concentration of the silane coupling agent in the spinning solution is 4 wt%) for blending and dissolving. The DMF / THF in the mixed solvent is 7 / 3 (v / v) to prepare spinning solutions of different concentrations of polyurethane.

[0056]

[0056] Stir the mixed solution in step S1 at room temperature for 2.5 h to completely dissolve it into a uniform and transparent spinning solution.

[0057]

[0057] Pump the spinning solution in step S2 into a syringe with a medical specification of 10 mL, replace it with a special stainless steel needle for electrospinning with a needle model of 21G, and clamp it on the fixture of the electrospinning machine.

[0058]

[0058] Wind the metal aluminum foil paper around the receiving metal roller, and then wind the commercial air filter paper as the paper base on the surface of the metal aluminum foil paper and fix it with paper base tape.

[0059]

[0059] Adjust the spinning solution injection speed of the electrospinning machine to 0.25 mm / min, the injection stroke to 10 mm, the receiving distance to 200 mm, the translation speed to 50 mm / min, the translation stroke to 200 mm, and the receiving roller rotation speed to 100 rpm / min. Electrospin nanofibers and deposit them on the surface of the paper base to form a fiber membrane.

[0060]

[0060] After the spinning is completed, place the double-layer air filter paper in an oven at 150 °C for drying for 1 h.

[0061]

[0061] Observe the morphology of the double-layer air filter paper prepared in this example using a scanning electron microscope, and use the Image J measurement software to test its fiber diameter. Take 50 fibers for each and calculate their average diameter.

[0062] Example 5

[0063] A preparation method of a double - layer air - filtering paper with high interfacial adhesion force is as follows:

[0064] S1. Dissolve polyurethane in a DMF / THF mixed solvent to prepare a homogeneous spinning solution with a mass concentration of 16 wt%, and then add silane coupling agent KH - 560 (the mass concentration of the silane coupling agent in the spinning solution is 4 wt%) for blending and dissolving. In the mixed solvent, DMF / THF is 7 / 3 (v / v).

[0065] S2. Stir the mixed solution in step S1 at room temperature for 2.5 h until it is completely dissolved into a homogeneous and transparent spinning solution.

[0066] S3. Pump the spinning solution in step S2 into a syringe with a medical specification of 10 mL, replace the needle with a special stainless - steel needle for electrospinning with a model of 21G, and clamp it on the fixture of the electrospinning machine.

[0067] S4. Wind the metal aluminum foil paper around the receiving metal roller, and then wind the commercial air - filtering paper as the paper base around the surface of the metal aluminum foil paper, and fix it with paper - based tape.

[0068] S6. Adjust the injection speed of the spinning solution of the electrospinning machine to 0.25 mm / min, the receiving distance to 200 mm, the translation speed to 50 mm / min, the translation stroke to 200 mm, and the rotation speed of the receiving roller to 100 rpm / min. Adjust the injection shape to 0, 2.5, 5, 7.5, and 10 mm respectively. Electrospin nanofibers and deposit them on the surface of the paper base to form a fiber membrane.

[0069] S7. After electrospinning, put all the double - layer air - filtering papers into an oven at 150 °C for drying for 1 h.

[0070] Use a thickness gauge to measure the average thickness of the nanofiber membrane of the double - layer air - filtering paper prepared in this example at normal temperature and pressure. Its average thickness at normal temperature and pressure is 2 μm, 4 μm, 6 μm, and 8 μm.

[0071] Use an automatic filter material tester to test the air - filtering resistance and the filtering efficiency for PM0.3 particles of the double - layer air - filtering paper prepared in this example under the condition of an air flow rate of 32 L / min.

[0072] Comparative Example 1

[0073] In this Comparative Example 1, a double - layer air - filtering paper is prepared by the preparation method described in paragraphs [0024 - 0031] of the specification with the application publication number of CN 117026685 A. The difference is that the paper base used in step S4 is a commercial air - filtering paper.

[0074] The double-layer air filter paper prepared in Comparative Example 1 was measured for its bonding strength by using a universal material tensile machine at normal temperature and pressure and the 180° peeling method. Select an appropriate fixture type, clamp the 3M tape with the upper fixture, fix the sample substrate with the lower fixture, and the tensile rate is 300 mm / min. Measure the change of force with displacement during the tensile test.

[0075] Comparative Example 2

[0076] In this comparative example, a commercial air filter paper without deposited polyurethane fibers was used to test its air filtration resistance and filtration efficiency for PM0.3 particulate matter under the condition of an air flow rate of 32 L / min by using an automatic filter material tester.

[0077] Tables 1 and 2 show the main process conditions for the preparation of Examples 1 to 5 and Comparative Examples 1 and 2 and the performance test results of the prepared double-layer air filter paper.

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082]

[0083] Note: Since Examples 1, 2, and 3 have explored the influencing factors of the adhesion strength between polyurethane fibers and the commercial air filter paper substrate; therefore, in Examples 4 and 5, a formulation with a low dosage of the agent and low energy consumption that ensures the highest adhesion strength was selected for subsequent exploration of the filtration performance.

[0084] In order to achieve the universality of the paper substrate, the present invention uses a commercial air filter paper as the paper substrate. Compared with the laboratory ultra-large filter paper used in the application publication number CN117026685A, the surface of the commercial air filter paper is coated with polyacrylic acid resin, which plays roles such as hydrophobicity and enhancing mechanical strength, resulting in a lack of active groups on its surface and being unable to generate a high adhesion strength with the paper substrate through hydrogen bonding like the laboratory ultra-large filter paper. In order to adhere polyurethane fibers to the surface of the commercial air filter paper to improve the air filtration performance and maintain stability during use, the present invention adds a silane coupling agent KH-560 to the spinning solution for blending. After subsequent electrospinning and deposition on the surface of the commercial air filter paper, the epoxy group of the silane coupling agent is connected to the carboxyl group and hydroxyl group on the surface of the commercial air filter paper by heating, and chemical covalent bonds are formed at the interface bonding part between the two to improve the interfacial adhesion strength, and the fiber diameter is reduced to the nanometer level by adjusting the parameters of the spinning solution to improve the filtration performance of the commercial air filter paper.

Claims

1. A preparation method of a double-layer air filter paper with high interfacial adhesion, characterized in that It is obtained by using air filter paper as the paper base, depositing nanofibers on the surface of the paper base through electrospinning to form a fiber membrane, and then drying and thermally crosslinking; the spinning solution used in the electrospinning is a spinning solution obtained by dissolving polyurethane in a mixed solvent of DMF / THF, and a silane coupling agent is added to the spinning solution for blending.

2. The preparation method of a double-layer air filter paper with high interfacial adhesion according to claim 1, characterized in that, The mass concentration of polyurethane in the spinning solution is 15 - 20 wt%.

3. The preparation method of a double-layer air filter paper with high interfacial adhesion according to claim 1, characterized in that, The mass concentration of the silane coupling agent added to the spinning solution is 2 - 6 wt%, and the type of the silane coupling agent is one of A151, A171, A172, KH-550, KH-560, KH-570, KH792 and DL602.

4. The preparation method of a double-layer air filter paper with high interfacial adhesion according to claim 1, characterized in that, The temperature of the drying and thermal crosslinking is 100 - 150 °C.

5. The preparation method of a double-layer air filter paper with high interfacial adhesion according to claim 1, characterized in that The time of the drying and thermal crosslinking is 1 - 3 h.

6. The preparation method of a double-layer air filter paper with high interfacial adhesion according to claim 1, characterized in that, The thickness of the fiber membrane formed on the surface of the paper base is 2 - 8 μm.

7. A double-layer air filter paper with high interfacial adhesion prepared by the preparation method according to any one of claims 1 - 6.

8. Application of the double-layer air filter paper with high interfacial adhesion prepared by the preparation method according to any one of claims 1 - 6 in the preparation of an air filter for an automobile engine; The interfacial adhesion of the double-layer air filter paper with high interfacial adhesion is 0.28 - 2.15 N / 12.7 mm; The air filtration resistance of the double-layer air filter paper with high interfacial adhesion is 104.2 - 124.7 Pa under the condition of an air flow rate of 32 L / min; The filtration efficiency of the double-layer air filter paper with high interfacial adhesion for PM0.3 particulate matter is 50.94 - 64.04% under the condition of an air flow rate of 32 L / min.

Images