Conductive far infrared honeycomb filter, preparation method and application thereof

Abstract

This invention relates to the field of filter material technology, and discloses a conductive far-infrared honeycomb filter material, its preparation method, and its application. The conductive far-infrared honeycomb filter material includes a honeycomb core formed by stacking porous channel far-infrared sheets, a conductive coating disposed on the outer surface of the porous channel sheets, and a conductive busbar area electrically connected to the conductive coating. When used in an air purification device, the conductive busbar area is electrically connected to a metal busbar on the opposite side, and is provided with an insulating edge sealing layer, an insulating cover or insulating potting layer, and an outer frame. The far-infrared substrate comprises a resin matrix and far-infrared functional fillers. The conductive coating may include a base coating, a conductive network layer containing graphene, carbon nanotubes, and / or ATO, and a protective layer. This filter material can capture particulate matter with electric field assistance under low wind resistance and has good resistance to spray cleaning, oil mist cleaning, and electrical operation stability.

Description

Technical Field

[0001] This invention relates to the field of filter material technology, and in particular to a conductive far-infrared honeycomb filter material, its preparation method and application. Background Technology

[0002] In industrial ventilation and purification, welding fume treatment, and oil mist exhaust gas treatment scenarios, filter materials often need to possess low air resistance, high particulate matter capture capacity, and washable and regenerable properties. Existing fiber-based filter materials typically rely on small pore size and high bulk density to achieve particulate matter retention. Although they have high filtration efficiency, they suffer from high operating resistance, are prone to clogging, and are difficult to clean and regenerate. Electrostatic precipitators have lower air resistance, but they are prone to problems such as dust accumulation, creepage, short circuits, and maintenance difficulties in high humidity, oil mist, and high dust environments.

[0003] CN110819001A discloses a flame-retardant and antibacterial composite polypropylene filter material and its preparation method. This method involves melt-blending and extruding polypropylene, functional negative ion releasing materials, nano-antibacterial agents, graphene oxide, flame retardants, and dispersants to obtain a polypropylene filter material with flame-retardant and antibacterial functions. This approach primarily improves the filter material's performance from a material formulation perspective, but it lacks a through-cell honeycomb channel structure, a surface conductive coating, a conductive current-collecting area, and an insulating electrode lead-out structure. Therefore, it struggles to simultaneously achieve low air resistance, electric field-assisted collection, and conductivity stability after cleaning under high-volume industrial conditions.

[0004] CN119463658A discloses a processing technology for a graphene composite conductive coating. This technology involves preparing a conductive coating using a self-made graphene / carbon nanotube conductive filler, an aqueous polyurethane solution, and a polyvinylpyrrolidone solution, and then applying it to the surface of a glass plate to form a conductive coating. While this method can improve the conductivity of the coating, it is primarily applicable to planar substrates and does not address the construction of conductive coatings on porous substrates such as polypropylene and polyphenylene sulfide. Furthermore, it does not solve the problems of coating adhesion stability and electrical connection reliability in honeycomb filter media under conditions of spray cleaning, oil mist contamination, and long-term ventilation and vibration. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a conductive far-infrared honeycomb filter material, its preparation method and application, so as to solve the problems that existing honeycomb filter materials are prone to increased wind resistance, insufficient stability of conductive coating cleaning and decreased electrical operation reliability after oil mist contamination when improving the collection efficiency of submicron particles.

[0006] To achieve the above objectives, the present invention provides a method for preparing a conductive far-infrared honeycomb filter material, comprising the following steps: 1) A far-infrared functional compound is obtained by mixing thermoplastic resin, far-infrared powder and additives; wherein the thermoplastic resin is one or more of polypropylene, polyphenylene sulfide, polyethylene terephthalate, polyetheretherketone and fluoroplastics; and the far-infrared powder is tourmaline powder or zirconium oxide powder. 2) The far-infrared functional mixture obtained in step 1) is extruded through an extruder and a multi-channel die to form a multi-channel far-infrared substrate; the multi-channel far-infrared substrate includes an upper wall, a lower wall, and a plurality of parallel through channels located between the upper wall and the lower wall. The through channels extend along the length of the substrate. The equivalent pore diameter of the through channels is 5-15mm, the center distance between adjacent through channels is 8-20mm, and the thickness of the ribs between the upper wall, the lower wall, and adjacent through channels is 0.5-1.2mm. 3) After cooling and shaping the porous channel far-infrared substrate obtained in step 2), cut it to obtain a porous channel sheet; 4) A conductive coating is formed on at least one outer surface of the porous channel sheet obtained in step 3) to obtain a conductive far-infrared sheet; the conductive coating is a composite conductive coating, which includes a base coating, a conductive network layer and a protective layer sequentially disposed on the outer surface of the porous channel sheet; the sheet resistance of the composite conductive coating is 20-60Ω / sq; 5) A conductive current-collecting area is formed on one side edge of the conductive far-infrared sheet obtained in step 4), and the conductive current-collecting area is electrically connected to the conductive coating; 6) Stack the conductive far-infrared sheets obtained in step 5) in multiple layers to form a continuous honeycomb channel between adjacent conductive far-infrared sheets; wherein, the conductive current-collecting area of ​​the odd-numbered conductive far-infrared sheets faces the first side of the honeycomb core, and the conductive current-collecting area of ​​the even-numbered conductive far-infrared sheets faces the second side of the honeycomb core, and the first side and the second side are two opposite sides of the honeycomb core. 7) Place the stacked conductive far-infrared sheets from step 6) into a limiting heat-bonding mold for local heat bonding. After cooling, trim the end face to obtain conductive far-infrared honeycomb filter material. The limiting heat-bonding mold has a limiting support part for limiting the compression deformation of the honeycomb channel.

[0007] Preferably, in step 1), the thermoplastic resin is polypropylene or polyphenylene sulfide; when the thermoplastic resin is polypropylene, the far-infrared functional compound includes 70-85 parts of polypropylene, 8-20 parts of tourmaline powder, 0.2-1.0 parts of antioxidant, and 0.2-1.0 parts of lubricant; when the thermoplastic resin is polyphenylene sulfide, the far-infrared functional compound includes 60-75 parts of polyphenylene sulfide, 10-20 parts of tourmaline-zirconia composite powder, 10-20 parts of chopped glass fiber, and 1-5 parts of flame retardant.

[0008] Preferably, in step 1), when the thermoplastic resin is polyphenylene sulfide, the polyphenylene sulfide is first dried at 120-150℃ for 3-5 hours, the far-infrared powder is dried at 100-120℃ for 1-3 hours, and then the polyphenylene sulfide, far-infrared powder and flame retardant are mixed and granulated by a twin-screw extruder. Short glass fibers are added through the side feed port of the twin-screw extruder to obtain high-temperature resistant far-infrared functional masterbatch.

[0009] Preferably, in step 4), before forming the conductive coating, the outer surface of the porous channel sheet is subjected to corona treatment, plasma treatment, or flame treatment to improve the bonding force between the conductive coating and the porous channel sheet.

[0010] Preferably, the base coating is one of waterborne polyurethane base coating, waterborne chlorinated polypropylene base coating, waterborne chlorinated polypropylene-waterborne polyurethane composite base coating, and polyamide-imide base coating; the base coating contains a silane coupling agent and / or a carbodiimide crosslinking agent.

[0011] Preferably, the conductive network layer is one of the following: a graphene conductive layer, a graphene-carbon nanotube conductive layer, a graphene-antimony-doped tin dioxide conductive layer, a graphene-carbon nanotube-antimony-doped tin dioxide ternary conductive network layer, and a carbon nanotube-antimony-doped tin dioxide conductive layer.

[0012] Preferably, the protective layer is one of a siloxane-modified waterborne polyurethane protective layer, a fluorinated acrylic protective layer, a fluorinated siloxane-modified waterborne polyurethane conductive protective layer, or a siloxane-modified polyimide protective layer; the wet film thickness of the protective layer is 3-8 μm.

[0013] Preferably, in step 4), the sheet resistance of the composite conductive coating is 20-60 Ω / sq.

[0014] Preferably, in step 5), the conductive busbar is formed of conductive carbon paste, conductive silver paste, conductive copper paste or metal foil strip, and the width of the conductive busbar is 5-15 mm, the dry film thickness is 20-50 μm, and the sheet resistance is 5-15 Ω / sq.

[0015] Preferably, in step 7), when the thermoplastic resin is polypropylene, the local heat bonding temperature is 175-190℃, the pressure is 0.05-0.15MPa, and the holding time is 10-30s; when the thermoplastic resin is polyphenylene sulfide, the local heat bonding temperature is 285-305℃, the pressure is 0.08-0.20MPa, and the holding time is 15-40s.

[0016] Preferably, in step 7), the height retention rate of the honeycomb channel after local thermal bonding is not less than 90%.

[0017] The present invention also discloses the application of the above-mentioned conductive far-infrared honeycomb filter material in air purification devices.

[0018] Specifically, the air purification device includes a housing, a fan, a low-current high-voltage DC power supply, and a control module. The conductive far-infrared honeycomb filter material is installed inside the housing. The first and second metal busbars are respectively installed on the conductive busbar areas on opposite sides of the conductive far-infrared honeycomb filter material and are respectively connected to the low-current high-voltage DC power supply, forming an electric field between adjacent conductive coatings. An insulating sealing layer, insulating cover, or insulating potting layer is provided between the first and second metal busbars to reduce the risk of surface creepage between the positive and negative electrodes. Dust-laden gas passes through the honeycomb channels of the conductive far-infrared honeycomb filter material under the action of the fan to achieve electric field-assisted collection of particulate matter.

[0019] The operating voltage of the low-current high-voltage DC power supply is 3-8kV, and the output current is no more than 0.2mA; the passing wind speed of the dust-laden gas is 0.5-2.5m / s.

[0020] The applications are used for industrial ventilation and purification, welding fume treatment, oil mist exhaust gas treatment, grinding dust treatment, cutting fume treatment, pre-filtration of fresh air systems, or recirculating air purification.

[0021] Preferably, the first metal busbar, the second metal busbar, and their electrical connection areas are insulated and potted with epoxy resin, silicone rubber, polyurethane insulating adhesive, or high-temperature resistant silicone rubber.

[0022] The beneficial effects of this invention are: This invention uses multi-channel far-infrared sheets to form a through honeycomb channel, and controls the channel deformation through a limiting mold during the local thermal bonding process, which can obtain a stable honeycomb structure while maintaining low operating wind resistance; in the embodiment, the operating wind resistance of the filter material at a wind speed of 1.5m / s is 55-68Pa.

[0023] The present invention provides a conductive coating on the outer surface of a porous channel sheet and leads out electrodes through the opposite sides of the conductive current-collecting areas of odd and even layers to form an electric field between adjacent conductive layers. Test results show that after the electric field is turned on, the filtration efficiency of 0.3μm NaCl aerosol is increased from 42.3%-48.5% in the state of electric field off to 78.6%-86.3%.

[0024] The present invention forms a composite conductive coating by means of a base layer, a conductive network layer and a protective layer, which can improve the bonding stability and cleaning resistance between the conductive coating and the far-infrared substrate; after 20 spray cleanings in Example 4, the sheet resistance increased from 30Ω / sq to 34Ω / sq, while the adhesion remained at level 0-1.

[0025] When the conductive far-infrared honeycomb filter material of the present invention is used in an air purification device, the electrode connection and operational safety are improved through the conductive busbar area, the metal busbar on the opposite side, the insulating sealing layer, the insulating cover and the insulating potting structure. In Example 4, after 10 cycles of oil mist contamination and cleaning, the electric field filtration efficiency was still 82.0%, and no short circuit or abnormal discharge occurred after 8 hours of continuous operation. Detailed Implementation

[0026] Polypropylene (PP), grade K8303, melt index 10g / 10min, sourced from Yanshan Petrochemical.

[0027] Tourmaline powder with an average particle size of 3μm.

[0028] Zirconia powder with an average particle size of 2 μm.

[0029] Aqueous graphene slurry with a solid content of 6%, graphene sheet diameter of 1-10 μm, number of graphene layers ≤10, and viscosity of 200-800 mPa·s at 25℃; after coating with a wet film thickness of 25 μm and drying at 120℃ for 4 min, the resulting conductive coating has a sheet resistance ≤50Ω / sq.

[0030] The conductive carbon paste, with a viscosity (Pa·s) of 10-30 and a volume resistivity (Ω·cm) of <2, is sourced from Suzhou Sierwei Nanotechnology Co., Ltd.

[0031] Waterborne polyurethane emulsion, brand name ALBERDINGK ® U 4000, with a solid content of 27-29%, is derived from Albertingkboley.

[0032] Carbon nanotube dispersion with a solid content of 3%, carbon nanotubes with an outer diameter of 5-20 nm, a length of 1-10 μm, and a viscosity of 100-500 mPa·s at 25℃.

[0033] Carboxyl-modified waterborne polyurethane emulsion, with a solid content of 30%, pH of 7-9, carboxyl content of 0.5-2.0 wt%, and viscosity of 100-800 mPa·s at 25℃.

[0034] Hydroxyl silicone oil emulsion, brand name: DY-OH5012, with a solid content of 30%, is sourced from Shandong Dayi Chemical Co., Ltd.

[0035] Water-based chlorinated polypropylene primer, solid content 18%, chlorine content 20-30wt%, viscosity 50-500mPa·s at 25℃.

[0036] Carbodiimide crosslinking agent, brand name XR-201, solid content 40%, sourced from Shanghai Xirun Chemical Technology Co., Ltd.

[0037] ATO aqueous dispersion is an antimony-doped tin dioxide aqueous dispersion with a solid content of 25%, an average particle size of 30-80 nm, an Sb doping amount of 5-15 wt%, and a viscosity of 100-600 mPa·s at 25℃.

[0038] Acrylic emulsion, grade: 8006S, solid content 42-48%, sourced from Shenzhen Feizhouniu Industrial Co., Ltd.

[0039] Fluorinated acrylic emulsion, brand name: HFS-F-3300, solid content 43%, pH 7-9, viscosity at 25℃ 50-500 mPa·s, fluorine content not less than 12%, sourced from Dongguan Baihong Environmental Protection Technology Co., Ltd.

[0040] Polyphenylene sulfide (PPS), grade A515, with a melt index of 80 g / 10 min, is sourced from Toray Torelina.

[0041] Short-cut glass fibers, 3mm in length and 10-13μm in diameter.

[0042] Polyamide-imide primer, solid content 12%, solvent is N-methylpyrrolidone, viscosity at 25℃ 100-1000mPa·s, temperature resistance ≥200℃.

[0043] A dispersion of single-walled carbon nanotubes with a solid content of 3%, the outer diameter of the single-walled carbon nanotubes being 1-3 nm and the length being 1-10 μm, and the viscosity at 25℃ being 100-500 mPa·s.

[0044] Polyamide-imide resin liquid, solid content 12%, solvent is N-methylpyrrolidone, temperature resistance ≥200℃.

[0045] Polyimide resin liquid, with a solid content of 10%, is a mixed solvent of N-methylpyrrolidone and dimethylacetamide. Its viscosity at 25℃ is 100-800 mPa·s, and its temperature resistance is ≥250℃.

[0046] Hydroxyl-terminated polydimethylsiloxane, 100-500 mPa·s, hydroxyl content 0.8-0.9 wt%.

[0047] The high-temperature resistant conductive carbon paste has a solid content of 35-55%, and the conductive filler is a mixture of conductive carbon black, graphite, and carbon nanotubes. The dry film sheet resistance is ≤10Ω / sq, the temperature resistance is ≥200℃, and the viscosity at 25℃ is 1000-5000mPa·s. The preparation method of the high-temperature resistant conductive carbon paste is as follows: Take 100 parts by weight of polyamide-imide resin liquid, 10 parts of conductive carbon black, 15 parts of graphite powder, 5 parts of carbon nanotube dispersion, and 30 parts of N-methylpyrrolidone. Disperse them at 25℃ and 1000r / min for 30min, then grind them in a sand mill until the fineness is ≤15μm to obtain the high-temperature resistant conductive carbon paste. The polyamide-imide resin liquid has a solid content of 12%, the carbon nanotube dispersion has a solid content of 3%, the carbon nanotubes have an outer diameter of 5-20nm, a length of 1-10μm, and a viscosity at 25℃ of 100-500mPa·s.

[0048] Insulating edge sealing adhesive, brand name DOWSIL 3145 RTV, dielectric strength 20kV / mm; volume resistivity 4.40×10⁻⁶ 14 Ω·cm, derived from DOWSIL.

[0049] Neutral cleaning agent, pH 6.5-7.5, nonionic surfactant content 10-20wt%.

[0050] No. 15 white oil, kinematic viscosity at 40℃: 13.5-16.5 mm. 2 / s.

[0051] High-temperature resistant conductive adhesive with a volume resistivity ≤1×10 -3 Ω·cm, temperature resistance ≥200℃, shear strength ≥5MPa.

[0052] High-temperature resistant silicone rubber, grade SYLGARD 170, dielectric strength 18kV / mm; volume resistivity 5.60×10⁻⁶. 17 Ω·cm, derived from DOW.

[0053] Example 1

[0054] A method for preparing a conductive far-infrared honeycomb filter material includes the following steps: 1) By weight, take 78 parts of polypropylene, 12 parts of tourmaline powder, 0.5 parts of antioxidant 1010 and 0.5 parts of calcium stearate and add them to a high-speed mixer and mix for 5 minutes to obtain far-infrared functional mixture; 2) The far-infrared functional mixture obtained in step 1) is added to a single-screw extruder and extruded through a multi-channel die to obtain a multi-channel far-infrared substrate; wherein, the extrusion temperature is 200℃, the multi-channel far-infrared substrate has multiple parallel circular through channels, the equivalent pore diameter of the through channels is 8mm, the center distance between adjacent through channels is 12mm, the thickness of the upper wall, lower wall and partition is 0.6mm, the extrusion width is 80cm, and the extrusion speed is 2m / min; 3) After cooling and shaping the porous channel far-infrared substrate obtained in step 2), cut it into porous channel sheets with a length of 80cm and a width of 80cm. 4) A water-based graphene slurry is coated onto the upper surface of the porous channel sheet obtained in step 3) using a gravure roller coating method to form a graphene conductive coating; wherein, the solid content of the water-based graphene slurry is 6%, the wet film thickness is 25μm, and it is dried with hot air at 120℃ for 4min after coating; the sheet resistance of the obtained graphene conductive coating is 45Ω / sq as tested by the four-probe method. 5) A conductive carbon paste is coated on one edge of the porous channel sheet obtained in step 4) to form a conductive busbar region. The conductive busbar region is electrically connected to the graphene conductive coating. The width of the conductive busbar region is 8 mm, the dry film thickness is 30 μm, and the sheet resistance is 10 Ω / sq. 6) Stack 60 layers of the porous channel sheet obtained in step 5) in the same direction to form a continuous honeycomb channel between adjacent sheets; wherein, the conductive current-collecting area of ​​the odd-numbered sheets faces the first side of the honeycomb core, and the conductive current-collecting area of ​​the even-numbered sheets faces the second side of the honeycomb core, and the first side and the second side are two opposite sides of the honeycomb core. 7) Place the stacked sheets from step 6) into a limiting hot press mold for localized thermal bonding; the limiting hot press mold has a limiting support part that matches the total thickness of the porous channel sheet, used to limit the compression deformation of the through channels during the hot pressing process; the thermal bonding temperature is 185℃, the pressure is 0.10MPa, the holding time is 20s, and after cooling, the end face is trimmed to obtain conductive far-infrared honeycomb filter material; the external dimensions of the conductive far-infrared honeycomb filter material are 800mm×800mm×500mm; it was measured that the height retention rate of the honeycomb channels after thermal bonding is 92%.

[0055] When using the conductive far-infrared honeycomb filter material obtained in step 7) in an air purification device, an insulating sealing adhesive is applied to the non-electrode lead-out side of the honeycomb filter material to form an insulating sealing layer; a first metal bus bar is installed on the odd-numbered conductive bus bar area on the first side of the honeycomb filter material as the positive electrode, and a second metal bus bar is installed on the even-numbered conductive bus bar area on the second side of the honeycomb filter material as the negative electrode; an insulating cover is set on the outside of the first metal bus bar and the second metal bus bar respectively, and the electrode connection area is insulated and potted with silicone rubber, and high-voltage wires are led out respectively; then the conductive far-infrared honeycomb filter material is installed in a stainless steel frame, and a silicone sealing strip is set between the frame and the honeycomb filter material to obtain a conductive far-infrared honeycomb filter material assembly for air purification.

[0056] The aforementioned conductive far-infrared honeycomb filter material assembly for air purification is installed in an industrial air purification device. The industrial air purification device includes a housing, a pre-filter, a fan, a low-current high-voltage DC power supply, and a control module. In use, the first and second metal busbars are connected to the low-current high-voltage DC power supply respectively, forming an electric field between adjacent conductive layers to assist in capturing particles entering the honeycomb channels. The high-voltage DC power supply operates at a voltage of 3-8kV, and its output current is limited to no more than 0.2mA.

[0057] Example 2

[0058] A method for preparing a conductive far-infrared honeycomb filter material includes the following steps: 1) By weight, take 78 parts of polypropylene, 12 parts of tourmaline powder, 0.5 parts of antioxidant 1010 and 0.5 parts of calcium stearate and add them to a high-speed mixer and mix for 5 minutes to obtain far-infrared functional mixture; 2) The far-infrared functional mixture obtained in step 1) is added to a single-screw extruder and extruded through a multi-channel die to obtain a multi-channel far-infrared substrate; wherein, the extrusion temperature is 200℃, the multi-channel far-infrared substrate has multiple parallel circular through channels, the equivalent pore diameter of the through channels is 8mm, the center distance between adjacent through channels is 12mm, the thickness of the upper wall, lower wall and partition is 0.6mm, the extrusion width is 80cm, and the extrusion speed is 2m / min; 3) After cooling and shaping the porous channel far-infrared substrate obtained in step 2), cut it into porous channel sheets with a length of 80cm and a width of 80cm. 4) The upper surface of the porous channel sheet obtained in step 3) is subjected to plasma treatment with a power of 800W and a speed of 5m / min; then a base coating, a conductive network layer and a protective layer are formed sequentially on the treated upper surface. The base coating is formed by an aqueous polyurethane primer, which is prepared as follows: Based on the preparation of 1000 parts of aqueous polyurethane primer, 633.3 parts of aqueous polyurethane emulsion are taken, and 296.7 parts of deionized water are added. The mixture is stirred at 500 r / min for 10 min to obtain a diluted aqueous polyurethane emulsion; Separately, silane coupling agent KH-560 is taken... 10.0 parts of anhydrous ethanol, 30.0 parts of deionized water were mixed, and the pH was adjusted to 4.5 with glacial acetic acid. The mixture was stirred and hydrolyzed at 25°C for 30 min to obtain KH-560 pre-hydrolyzed solution. The KH-560 pre-hydrolyzed solution was added to the diluted waterborne polyurethane emulsion under stirring, and the mixture was stirred at 500 r / min for 20 min. The mixture was then filtered through a 200-mesh filter to obtain waterborne polyurethane primer. The primer layer was applied by gravure roller coating with a wet film thickness of 8 μm. After coating, the primer was dried with hot air at 90°C for 2 min. The conductive network layer is formed by a graphene-carbon nanotube composite conductive slurry, which comprises 100 parts of aqueous graphene slurry, 10 parts of carbon nanotube dispersion, 8 parts of carboxyl-modified aqueous polyurethane emulsion, and 15 parts of deionized water; wherein the solid content of the aqueous graphene slurry is 6%, the solid content of the carbon nanotube dispersion is 3%, and the solid content of the carboxyl-modified aqueous polyurethane emulsion is 30%; the conductive network layer is coated by gravure roller coating, with a wet film thickness of 22 μm, and is dried with hot air at 120°C for 4 min after coating. The protective layer is formed by a siloxane-modified waterborne polyurethane protective liquid with a solid content of 10%. The protective layer is applied by roller coating with a wet film thickness of 5 μm. After coating, it is dried with hot air at 100°C for 3 min to obtain a conductive far-infrared sheet with a wash-resistant composite conductive coating on the surface. The sheet resistance of the composite conductive coating is 38 Ω / sq as tested by the four-probe method. 5) A conductive carbon paste is coated on one edge of the conductive far-infrared sheet obtained in step 4) to form a conductive busbar area. The conductive busbar area is electrically connected to the composite conductive coating. The width of the conductive busbar area is 8 mm, the dry film thickness is 30 μm, and the sheet resistance is 10 Ω / sq. 6) Stack 60 layers of the conductive far-infrared sheet obtained in step 5) in the same direction to form a continuous honeycomb channel between adjacent sheets; wherein, the conductive current-collecting area of ​​the odd-numbered sheets faces the first side of the honeycomb core, and the conductive current-collecting area of ​​the even-numbered sheets faces the second side of the honeycomb core, and the first side and the second side are two opposite sides of the honeycomb core. 7) Place the stacked sheets from step 6) into a limiting hot press mold for localized thermal bonding. The thermal bonding temperature is 185℃, the pressure is 0.10MPa, and the holding time is 20s. After cooling, the end face is trimmed to obtain conductive far-infrared honeycomb filter material. The external dimensions of the conductive far-infrared honeycomb filter material are 800mm×800mm×500mm. It was measured that the height retention rate of the honeycomb channel after thermal bonding is 93%.

[0059] When using the conductive far-infrared honeycomb filter material obtained in step 7) in an air purification device, an insulating sealing adhesive is applied to the non-electrode lead-out side of the honeycomb filter material to form an insulating sealing layer; a first metal bus bar is installed on the odd-numbered conductive bus bar area on the first side of the honeycomb filter material as the positive electrode, and a second metal bus bar is installed on the even-numbered conductive bus bar area on the second side of the honeycomb filter material as the negative electrode; an insulating cover is set on the outside of the first metal bus bar and the second metal bus bar respectively, and the electrode connection area is insulated and potted with silicone rubber, and high-voltage wires are led out respectively; then the conductive far-infrared honeycomb filter material is installed in a stainless steel frame, and a silicone sealing strip is set between the frame and the honeycomb filter material to obtain a conductive far-infrared honeycomb filter material assembly for air purification.

[0060] The preparation method of the siloxane-modified waterborne polyurethane protective liquid is as follows: by mass, take 100 parts of carboxyl-modified waterborne polyurethane emulsion, 8 parts of hydroxyl silicone oil emulsion, 20 parts of deionized water and 0.2 parts of polyether-modified polysiloxane leveling agent, stir at 25℃ and 600r / min for 30min to obtain the siloxane-modified waterborne polyurethane protective liquid; the polyether-modified polysiloxane leveling agent is TEGO® Glide 410, with an active ingredient content of 100%, and is a transparent liquid, sourced from EvonikOperations GmbH.

[0061] Example 3

[0062] A method for preparing an oil-mist-resistant conductive far-infrared honeycomb filter material includes the following steps: 1) By weight, take 78 parts of polypropylene, 12 parts of tourmaline powder, 0.5 parts of antioxidant 1010, and 0.5 parts of calcium stearate and add them to a high-speed mixer and mix for 5 minutes to obtain far-infrared functional mixture; wherein, the melt index of the polypropylene is 10 g / 10 min, and the average particle size of the tourmaline powder is 3 μm; 2) The far-infrared functional mixture obtained in step 1) is added to a single-screw extruder and extruded through a multi-channel die to obtain a multi-channel far-infrared substrate; wherein, the extrusion temperature is 200℃, the multi-channel far-infrared substrate has multiple parallel circular through channels, the equivalent pore diameter of the through channels is 8mm, the center distance between adjacent through channels is 12mm, the thickness of the upper wall, lower wall and partition is 0.6mm, the extrusion width is 80cm, and the extrusion speed is 2m / min; 3) After cooling and shaping the porous channel far-infrared substrate obtained in step 2), cut it into porous channel sheets with a length of 80cm and a width of 80cm. 4) The upper surface of the porous channel sheet obtained in step 3) is subjected to corona treatment with a power of 1.0 kW and a speed of 6 m / min; then, an anchoring base coating, a graphene-ATO conductive layer and a fluorine-containing protective layer are formed sequentially on the treated upper surface. The anchoring primer is formed by an aqueous chlorinated polypropylene primer with a solid content of 18% and contains 1.5% by mass of a carbodiimide crosslinking agent. The anchoring primer is applied by gravure roller coating with a wet film thickness of 6 μm and is dried in hot air at 95°C for 2 min after coating. The graphene-ATO conductive layer is formed by a graphene-ATO composite slurry, which includes 100 parts of aqueous graphene slurry, 35 parts of aqueous ATO dispersion, 6 parts of acrylic emulsion, and 10 parts of deionized water. The graphene-ATO conductive layer is coated onto the upper surface by spraying, with a wet film thickness of 28 μm, and then dried with hot air at 125°C for 5 min. The fluorinated protective layer is formed by a fluorinated acrylic protective liquid with a solid content of 8%. The fluorinated protective layer is applied by roller coating with a wet film thickness of 4 μm. After coating, it is dried with hot air at 110°C for 4 min to obtain a conductive far-infrared sheet with an oil-mist-resistant and washable composite conductive coating. The sheet resistance of the composite conductive coating is 42 Ω / sq as measured by the four-probe method. 5) A conductive carbon paste is coated on one edge of the conductive far-infrared sheet obtained in step 4) to form a conductive busbar area. The conductive busbar area is electrically connected to the composite conductive coating. The width of the conductive busbar area is 8 mm, the dry film thickness is 30 μm, and the sheet resistance is 10 Ω / sq. 6) Stack 60 layers of the conductive far-infrared sheet obtained in step 5) in the same direction to form a continuous honeycomb channel between adjacent sheets; wherein, the conductive current-collecting area of ​​the odd-numbered sheets faces the first side of the honeycomb core, and the conductive current-collecting area of ​​the even-numbered sheets faces the second side of the honeycomb core, and the first side and the second side are two opposite sides of the honeycomb core. 7) Place the stacked sheets from step 6) into a limiting hot press mold for localized thermal bonding. The thermal bonding temperature is 185℃, the pressure is 0.10MPa, and the holding time is 20s. After cooling, the end face is trimmed to obtain conductive far-infrared honeycomb filter material. The external dimensions of the conductive far-infrared honeycomb filter material are 800mm×800mm×500mm. It was measured that the height retention rate of the honeycomb channel after thermal bonding is 92%.

[0063] When using the conductive far-infrared honeycomb filter material obtained in step 7) in an air purification device, an insulating sealing adhesive is applied to the non-electrode lead-out side of the honeycomb filter material to form an insulating sealing layer; a first metal bus bar is installed on the odd-numbered conductive bus bar area on the first side of the honeycomb filter material as the positive electrode, and a second metal bus bar is installed on the even-numbered conductive bus bar area on the second side of the honeycomb filter material as the negative electrode; an insulating cover is set on the outside of the first metal bus bar and the second metal bus bar respectively, and the electrode connection area is insulated and potted with silicone rubber, and high-voltage wires are led out respectively; then the conductive far-infrared honeycomb filter material is installed in a stainless steel frame, and a silicone sealing strip is set between the frame and the honeycomb filter material to obtain a conductive far-infrared honeycomb filter material assembly for air purification.

[0064] The preparation method of the fluorinated acrylic protective liquid is as follows: 100 parts by mass of fluorinated acrylic emulsion, 20 parts of deionized water, and 0.2 parts of polyether-modified polysiloxane leveling agent are taken and stirred at 25℃ and 500r / min for 20min to obtain the fluorinated acrylic protective liquid; wherein, the polyether-modified polysiloxane leveling agent is TEGO® Glide 410, with an active ingredient content of 100%, and is a transparent liquid, sourced from Evonik Operations GmbH.

[0065] Example 4

[0066] A method for preparing a conductive far-infrared honeycomb filter material includes the following steps: 1) By weight, take 78 parts of polypropylene, 12 parts of tourmaline powder, 0.5 parts of antioxidant 1010 and 0.5 parts of calcium stearate and add them to a high-speed mixer and mix for 5 minutes to obtain far-infrared functional mixture; 2) The far-infrared functional mixture obtained in step 1) is added to a single-screw extruder and extruded through a multi-channel die to obtain a multi-channel far-infrared substrate; wherein, the extrusion temperature is 200℃, the multi-channel far-infrared substrate has multiple parallel circular through channels, the equivalent pore diameter of the through channels is 8mm, the center distance between adjacent through channels is 12mm, the thickness of the upper wall, lower wall and partition is 0.6mm, the extrusion width is 80cm, and the extrusion speed is 2m / min; 3) After cooling and shaping the porous channel far-infrared substrate obtained in step 2), cut it into porous channel sheets with a length of 80cm and a width of 80cm. 4) The upper surface of the porous channel sheet obtained in step 3) is subjected to corona treatment with a power of 1.2kW and a speed of 5m / min; then a composite anchoring base coating, a ternary conductive network layer and a transparent protective layer are formed sequentially on the treated upper surface. The composite anchoring primer is formed by an aqueous chlorinated polypropylene-waterborne polyurethane composite primer, which includes 70 parts of aqueous chlorinated polypropylene emulsion, 30 parts of carboxyl-modified aqueous polyurethane emulsion, 1.5 parts of silane coupling agent KH-560, and 2.0 parts of carbodiimide crosslinking agent. The composite anchoring primer is applied by gravure roller coating, with a wet film thickness of 6 μm, and is dried in hot air at 95°C for 2 min after coating. The ternary conductive network layer is formed by a graphene-carbon nanotube-ATO composite conductive slurry, which includes 100 parts of aqueous graphene slurry, 12 parts of carbon nanotube dispersion, 20 parts of aqueous ATO dispersion, 8 parts of carboxyl-modified aqueous polyurethane emulsion, and 12 parts of deionized water. The ternary conductive network layer is coated by gravure roller coating, with a wet film thickness of 24 μm, and then dried with hot air at 120°C for 5 min. The conductive protective layer is formed by a fluorinated siloxane-modified aqueous polyurethane protective liquid. The conductive protective layer is coated by roller coating, with a wet film thickness of 4μm. After coating, it is dried with hot air at 105℃ for 3min and then cured at 130℃ for 10min to obtain a conductive far-infrared sheet with a washable composite conductive coating on the surface. The sheet resistance of the composite conductive coating is 30Ω / sq as tested by the four-probe method. 5) A conductive carbon paste is coated on one edge of the conductive far-infrared sheet obtained in step 4) to form a conductive busbar area. The conductive busbar area is electrically connected to the composite conductive coating. The width of the conductive busbar area is 8 mm, the dry film thickness is 30 μm, and the sheet resistance is 8 Ω / sq. 6) Stack 60 layers of the conductive far-infrared sheet obtained in step 5) in the same direction to form a continuous honeycomb channel between adjacent sheets; wherein, the conductive current-collecting area of ​​the odd-numbered sheets faces the first side of the honeycomb core, and the conductive current-collecting area of ​​the even-numbered sheets faces the second side of the honeycomb core, and the first side and the second side are two opposite sides of the honeycomb core. 7) Place the stacked sheets from step 6) into a limiting hot press mold for localized thermal bonding. The thermal bonding temperature is 185℃, the pressure is 0.10MPa, and the holding time is 20s. After cooling, the end face is trimmed to obtain conductive far-infrared honeycomb filter material. The external dimensions of the conductive far-infrared honeycomb filter material are 800mm×800mm×500mm. It was measured that the height retention rate of the honeycomb channel after thermal bonding is 94%.

[0067] When using the conductive far-infrared honeycomb filter material obtained in step 7) in an air purification device, an insulating sealing adhesive is applied to the non-electrode lead-out side of the honeycomb filter material to form an insulating sealing layer; a first metal bus bar is installed on the odd-numbered conductive bus bar area on the first side of the honeycomb filter material as the positive electrode, and a second metal bus bar is installed on the even-numbered conductive bus bar area on the second side of the honeycomb filter material as the negative electrode; an insulating cover is set on the outside of the first metal bus bar and the second metal bus bar respectively, and the electrode connection area is insulated and potted with silicone rubber, and high-voltage wires are led out respectively; then the conductive far-infrared honeycomb filter material is installed in a stainless steel frame, and a silicone sealing strip is set between the frame and the honeycomb filter material to obtain a conductive far-infrared honeycomb filter material assembly for air purification.

[0068] The fluorinated siloxane-modified waterborne polyurethane protective liquid is composed of the following components: 100 parts of fluorinated siloxane-modified waterborne polyurethane emulsion, 4 parts of ATO waterborne dispersion, 1 part of carbon nanotube dispersion, and 8 parts of deionized water.

[0069] The preparation method of fluorinated siloxane-modified waterborne polyurethane emulsion is as follows: by mass, take 100 parts of carboxyl-modified waterborne polyurethane emulsion, 20 parts of fluorinated acrylic emulsion, 10 parts of hydroxyl silicone oil emulsion, 40 parts of deionized water and 2 parts of carbodiimide crosslinking agent, and stir for 40 min at 25℃ and 600 r / min to obtain fluorinated siloxane-modified waterborne polyurethane emulsion.

[0070] Compared with Example 1, Example 4 uses a composite anchoring base coating, a ternary conductive network layer and a transparent protective layer to form a washable composite conductive coating. It also adopts a conductive busbar, opposite side lead-out electrodes and an insulating edge sealing structure, which can improve the coating adhesion stability, post-cleaning resistance stability and electric field operation reliability while maintaining low operating wind resistance.

[0071] Test Example 1 Adhesion and spray cleaning resistance tests of composite conductive coatings The conductive far-infrared sheet obtained in step 5 of Examples 1-4 was used as the test sample. The coating adhesion was tested according to GB / T9286-2021 "Cross-cut test for paints and varnishes", and the adhesion level was recorded. The sheet resistance of the conductive coating was tested using a four-probe sheet resistance meter, with 5 locations randomly tested for each sample, and the average value was taken.

[0072] The spray cleaning cycle was performed as follows: The sample was placed in the spray cleaning device and sprayed with room temperature deionized water at a pressure of 0.5 MPa for 2 minutes; then rinsed with deionized water for 1 minute, drained for 30 seconds, and dried with hot air at 60°C for 10 minutes, which was recorded as one spray cleaning cycle. After 20 consecutive spray cleaning cycles, the coating appearance was observed, and the sheet resistance and adhesion grade were tested.

[0073] Table 1. Adhesion and spray cleaning resistance of composite conductive coatings

[0074] As shown in Table 1, in Example 1, a single-layer graphene conductive coating was used. After 20 spray cleaning cycles, the sheet resistance increased from 45 Ω / sq to 73 Ω / sq, with a sheet resistance change rate of 62.2%. Slight peeling was observed at the edge of the coating, indicating that the single-layer graphene coating was not stable enough under repeated spray cleaning conditions.

[0075] In Examples 2-4, after applying the composite conductive coating, the sheet resistance change rate after 20 spray cleaning cycles was significantly reduced, and the adhesion retention was significantly improved. Among them, Example 4 had the lowest initial sheet resistance, and after 20 spray cleaning cycles, the sheet resistance only increased to 34 Ω / sq, with a sheet resistance change rate of 13.3%, and the adhesion remained at the 0-1 level. This indicates that the composite anchoring base coating, ternary conductive network layer, and transparent protective layer can synergistically improve the bonding stability and cleaning resistance between the conductive coating and the polypropylene substrate.

[0076] Test Example 2 Testing of filtration efficiency, operating resistance and electric field-assisted capture performance of conductive far-infrared honeycomb filter material The conductive far-infrared honeycomb filter material obtained in step 7) of Examples 1-4 was used as the test sample. When the electric field test was activated, metal electrode plates were temporarily clamped onto the conductive current-collecting areas on the first and second sides of the honeycomb filter material, and connected to a low-current, high-voltage DC power supply. Filtration efficiency and operating air resistance were tested according to GB / T 14295-2019 "Air Filters". The test aerosol was NaCl aerosol with a particle size of 0.3 μm and a test air velocity of 1.5 m / s. A particle counter was used to detect the particle concentration upstream and downstream of the filter material, and the filtration efficiency was calculated.

[0077] The test is divided into two states: electric field off and electric field on. In the electric field off state, no voltage is applied to the conductive layer, and only the mechanical trapping and surface deposition effects of the honeycomb filter material itself are tested. In the electric field on state, the positive and negative terminals of the honeycomb filter material are connected to a low-current high-voltage DC power supply, with an operating voltage of 5kV and an output current limited to no more than 0.2mA, to form an electric field between adjacent conductive layers and test the electric field-assisted trapping performance.

[0078] The sample was then subjected to 20 spray cleaning cycles using the same method described in Test Example 1. The filtration efficiency and operating resistance under the electric field activated state were then tested again, and the filtration efficiency retention rate was calculated. Filtration efficiency retention rate = (Filtration efficiency after 20 spray cleaning cycles / Initial electric field activated filtration efficiency) × 100%.

[0079] Table 2 Filtration efficiency of conductive far-infrared honeycomb filter material

[0080] As shown in Table 2, under the condition of closed electric field, the filtration efficiency of Examples 1-4 for 0.3μm NaCl aerosol was 42.3%-43.5%, indicating that the honeycomb filter material itself has a certain mechanical interception and surface deposition effect, but its ability to capture submicron particles is limited. After the electric field was turned on, the filtration efficiency of Examples 1-4 was significantly improved, indicating that the electric field formed between adjacent conductive layers can play an auxiliary role in enhancing the capture of particles.

[0081] In Example 1, the filtration efficiency decreased from 78.6% to 69.8% after 20 spray cleaning cycles, with a retention rate of 88.8%. This was mainly due to the increased sheet resistance and localized coating detachment of the single-layer graphene conductive coating after cleaning, leading to a decrease in the electric field-assisted collection capability. Examples 2-4 maintained high filtration efficiencies after 20 spray cleaning cycles. In Example 4, the filtration efficiency after cleaning was 82.8%, with a retention rate of 97.8%, indicating that the wash-resistant composite conductive coating of Example 4 can maintain a relatively stable conductive path and electric field-assisted collection capability after cleaning.

[0082] Meanwhile, the initial operating air resistance of Examples 1-4 was 55-58 Pa, and the operating air resistance after 20 spray cleaning cycles was 58-61 Pa, indicating that the honeycomb channel formed by limiting hot pressing can maintain a low air resistance, and no obvious channel blockage or structural collapse occurred after repeated spray cleaning.

[0083] Test Example 3 Oil mist cleaning resistance and electrical operation stability test of conductive far-infrared honeycomb filter material The conductive far-infrared honeycomb filter material obtained in step 7) of Examples 1-4 was used as a test sample. The first metal busbar, second metal busbar, insulating edge sealing layer, insulating cover, and insulating potting layer were installed according to the application assembly method to obtain a conductive far-infrared honeycomb filter material assembly for air purification. The sample was installed in a simulated oil mist pollution test device, and No. 15 white oil was used to form an oil mist aerosol. The oil mist concentration was controlled at 80±10 mg / m³. 3 The test wind speed was 1.5 m / s, and the oil mist was continuously introduced for 8 hours before cleaning.

[0084] For cleaning, a 0.3% (w / w) neutral cleaning agent aqueous solution was sprayed at 50°C for 2 minutes at a spray pressure of 0.5 MPa. This was followed by rinsing with deionized water for 1 minute, draining for 30 seconds, and then drying with hot air at 60°C for 10 minutes. This was recorded as one oil mist contamination and cleaning cycle. After 10 consecutive oil mist contamination and cleaning cycles, the sheet resistance of the conductive coating, the filtration efficiency of 0.3 μm NaCl aerosol under an activated electric field, and the operating air resistance were tested.

[0085] The electrical operation stability test method is as follows: After completing 10 cycles of oil mist contamination and cleaning, the sample is connected to a low-current high-voltage DC power supply with a working voltage of 5kV and an output current limited to no more than 0.2mA. The sample is run continuously for 8 hours under ventilation conditions of 1.5m / s, and the number of short circuits, abnormal discharges, and stable operation leakage current are recorded during the operation.

[0086] Table 3. Oil mist cleaning resistance and electrical operation stability test of conductive far-infrared honeycomb filter material assembly

[0087] As shown in Table 3, in Example 1, a single-layer graphene conductive coating was used. After 10 cycles of oil mist contamination and cleaning, the sheet resistance increased from 45Ω / sq to 88Ω / sq, with a sheet resistance change rate of 95.6%. The filtration efficiency of the electric field decreased to 64.2%. Furthermore, short circuits and abnormal discharges occurred during 8 hours of continuous operation. This indicates that the single-layer graphene coating has insufficient conductivity stability and electrical reliability under oil mist contamination and repeated cleaning conditions.

[0088] Examples 2-4 employ a wash-resistant composite conductive coating and improve electrode connection stability through a conductive busbar, opposite-side lead-out electrodes, an insulating sealing layer, and an insulating potting structure. After 10 cycles of oil mist contamination and cleaning, Examples 2-4 did not exhibit short circuits or abnormal discharges, and their stable operating leakage current was significantly lower than that of Example 1, indicating that they can meet the electrical operational stability requirements under oil mist and cleaning conditions.

[0089] In Example 4, the sheet resistance was 36Ω / sq after 10 oil mist cleaning cycles, the filtration efficiency remained at 82.0% when the electric field was turned on, the operating wind resistance was 60Pa, and no short circuit or abnormal discharge occurred after 8 hours of continuous operation. It had the best overall performance in terms of oil mist cleaning resistance and electrical operation stability.

[0090] Example 5

[0091] A method for preparing a high-temperature resistant conductive far-infrared honeycomb filter material includes the following steps: 1) By weight, take 68 parts of polyphenylene sulfide, 15 parts of tourmaline-zirconia composite powder, 15 parts of chopped glass fiber, and 2 parts of phosphorus-nitrogen flame retardant; the tourmaline-zirconia composite powder is obtained by mixing tourmaline powder and zirconia powder in a mass ratio of 3:1; the phosphorus-nitrogen flame retardant is obtained by mixing ammonium polyphosphate and melamine polyphosphate in a mass ratio of 2:1. 2) Dry the polyphenylene sulfide granules from step 1) at 140℃ for 4 hours; dry the tourmaline-zirconia composite powder at 110℃ for 2 hours; add the dried polyphenylene sulfide granules, tourmaline-zirconia composite powder and phosphorus-nitrogen flame retardant into a high-speed mixer and mix for 8 minutes to obtain a high-temperature resistant far-infrared functional mixture. 3) The high-temperature resistant far-infrared functional mixture obtained in step 2) is added to a twin-screw extruder for blending and granulation to obtain high-temperature resistant far-infrared functional masterbatch; wherein, the temperatures from zone 1 to the die head of the twin-screw extruder are 290℃, 300℃, 310℃, 320℃, 320℃ and 315℃ respectively, the screw speed is 180r / min, and the chopped glass fiber is added from the side feed port of the twin-screw extruder, and the glass fiber retention length in the obtained high-temperature resistant far-infrared functional masterbatch is 0.2-1.0mm; 4) The high-temperature resistant far-infrared functional masterbatch obtained in step 3) is added to a single-screw extruder and extruded through a multi-channel die to obtain a high-temperature resistant multi-channel far-infrared substrate; wherein, the extrusion temperature is 300℃, the high-temperature resistant multi-channel far-infrared substrate has multiple parallel circular through channels, the through channels extend along the length of the substrate, the equivalent pore diameter of the through channels is 10mm, the center distance between adjacent through channels is 15mm, the thickness of the upper wall, lower wall and partition is 0.8mm, the extrusion width is 60cm, and the extrusion speed is 0.8m / min; 5) After the high-temperature resistant porous channel far-infrared substrate obtained in step 4) is cooled by air cooling and shaping rollers, it is cut along the length to obtain a porous channel sheet with a length of 60cm and a width of 60cm. 6) The upper surface of the porous channel sheet obtained in step 5) is subjected to plasma treatment with a power of 1.2kW and a speed of 4m / min; then a high-temperature resistant base coating, a CNT-ATO composite conductive layer and a high-temperature resistant protective layer are formed sequentially on the treated upper surface. The high-temperature resistant base coating is formed from a polyamide-imide base coating liquid with a solid content of 12% and contains 1.0% by mass of a silane coupling agent KH-560. The high-temperature resistant base coating is applied by spraying, with a wet film thickness of 8 μm, and is then dried in hot air at 180°C for 5 min after application. The CNT-ATO composite conductive layer is formed by carbon nanotube-ATO composite conductive slurry, which includes 100 parts of single-walled carbon nanotube dispersion, 25 parts of ATO aqueous dispersion, 20 parts of polyamide-imide resin liquid, and 15 parts of N-methylpyrrolidone. The CNT-ATO composite conductive layer is coated onto the upper surface by spraying, with a wet film thickness of 30 μm. After coating, it is dried with hot air at 180℃ for 8 min, and then cured at 230℃ for 15 min. The high-temperature resistant protective layer is formed by a siloxane-modified polyimide protective liquid with a solid content of 8%. The high-temperature resistant protective layer is applied by spraying, with a wet film thickness of 5 μm. After coating, it is dried with hot air at 200°C for 5 min and then cured at 250°C for 10 min to obtain a high-temperature resistant conductive far-infrared sheet with a high-temperature resistant composite conductive coating on the surface. The sheet resistance of the high-temperature resistant composite conductive coating is 28 Ω / sq, as tested by the four-probe method. 7) A high-temperature resistant conductive far-infrared sheet obtained in step 6) is coated with a high-temperature resistant conductive carbon paste on one edge to form a conductive busbar area. The conductive busbar area is electrically connected to the high-temperature resistant composite conductive coating. The width of the conductive busbar area is 10 mm, the dry film thickness is 35 μm, and the sheet resistance is 8 Ω / sq. 8) Stack 80 layers of the high-temperature resistant conductive far-infrared sheet obtained in step 7) in the same direction to form a continuous honeycomb channel between adjacent sheets; wherein, the conductive current-collecting area of ​​the odd-numbered sheets faces the first side of the honeycomb filter material, and the conductive current-collecting area of ​​the even-numbered sheets faces the second side of the honeycomb filter material, and the first side and the second side are two opposite sides of the honeycomb filter material. 9) Place the stacked sheets from step 8) into a limiting heat welding mold for local heat bonding; the limiting heat welding mold has a limiting support part that matches the total thickness of the porous channel sheet, used to limit the compression deformation of the through channels during the heat bonding process; the local heat bonding temperature is 295℃, the pressure is 0.12MPa, the holding time is 25s, and after cooling, the end face is trimmed to obtain a high-temperature resistant conductive far-infrared honeycomb filter material; the external dimensions of the high-temperature resistant conductive far-infrared honeycomb filter material are 600mm×600mm×850mm; it was measured that the height retention rate of the honeycomb channels after heat bonding is 93%.

[0092] When using the high-temperature resistant conductive far-infrared honeycomb filter material obtained in step 9) in an air purification device, a ceramic insulating sheet and a high-temperature resistant silicone rubber insulating sealing layer are set on the non-electrode lead-out side of the honeycomb filter material; a first stainless steel busbar is installed on the odd-numbered conductive busbar area on the first side of the honeycomb filter material as the positive electrode, and a second stainless steel busbar is installed on the even-numbered conductive busbar area on the second side of the honeycomb filter material as the negative electrode. The first and second stainless steel busbars are fixedly connected to the corresponding conductive busbar area by high-temperature resistant conductive adhesive; a high-temperature resistant insulating cover is set on the outside of the first and second stainless steel busbars respectively, and the electrode connection area is potted with high-temperature resistant silicone rubber, and high-voltage wires are led out respectively; then the high-temperature resistant conductive far-infrared honeycomb filter material is installed in a 304 stainless steel frame, and a high-temperature resistant silicone sealing strip is set between the frame and the honeycomb filter material to obtain a high-temperature resistant conductive far-infrared honeycomb filter material assembly for air purification.

[0093] A siloxane-modified polyimide protective liquid, with a solid content of 8% and a siloxane content of 3-8 wt%, is prepared using a mixed solvent of N-methylpyrrolidone and dimethylacetamide. The viscosity at 25℃ is 100-800 mPa·s, and the temperature resistance is ≥250℃. The preparation method is as follows: Take 100 parts by weight of polyimide resin liquid, 5 parts by weight of hydroxyl-terminated polydimethylsiloxane, 20 parts by weight of N-methylpyrrolidone, and 0.2 parts by weight of polyether-modified polysiloxane leveling agent. Stir at 60℃ and 500 r / min for 60 min to obtain the siloxane-modified polyimide protective liquid. The polyether-modified polysiloxane leveling agent is brand TEGO. ® Glide 410 is from Evonik Operations GmbH.

[0094] The aforementioned high-temperature resistant conductive far-infrared honeycomb filter material assembly for air purification is installed in an industrial air purification device. The industrial air purification device includes a housing, a pre-filter, a fan, a low-current high-voltage DC power supply, and a control module. In use, the first and second stainless steel busbars are connected to the low-current high-voltage DC power supply respectively, forming an electric field between adjacent conductive layers to assist in capturing particulate matter entering the honeycomb channels. The high-voltage DC power supply operates at a voltage of 3-8kV, and its output current is limited to no more than 0.2mA.

[0095] Tests showed that the high-temperature resistant conductive far-infrared honeycomb filter material prepared in this embodiment had a wind resistance of 68 Pa at a wind speed of 1.5 m / s; its collection efficiency for 0.3 μm NaCl aerosol was 48.5% in the off-field state and 86.3% in the on-field state; after thermal aging at 150℃ for 168 h, the sheet resistance of the high-temperature resistant composite conductive coating was 32 Ω / sq, and its collection efficiency for 0.3 μm NaCl aerosol was 84.8% in the on-field state. No short circuit or abnormal discharge phenomenon was observed after 8 h of continuous operation.

[0096] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing an electrically conductive far infrared honeycomb filter material, characterized by, Includes the following steps: 1) A far-infrared functional compound is obtained by mixing thermoplastic resin, far-infrared powder and additives; wherein the thermoplastic resin is one or more of polypropylene, polyphenylene sulfide, polyethylene terephthalate, polyetheretherketone and fluoroplastics; and the far-infrared powder is tourmaline powder or zirconium oxide powder. 2) The far-infrared functional mixture obtained in step 1) is extruded through an extruder and a multi-channel die to form a multi-channel far-infrared substrate; the multi-channel far-infrared substrate includes an upper wall, a lower wall, and a plurality of parallel through channels located between the upper wall and the lower wall. The through channels extend along the length of the substrate. The equivalent pore diameter of the through channels is 5-15mm, the center distance between adjacent through channels is 8-20mm, and the thickness of the ribs between the upper wall, the lower wall, and adjacent through channels is 0.5-1.2mm. 3) After cooling and shaping the porous channel far-infrared substrate obtained in step 2), cut it to obtain a porous channel sheet; 4) A conductive coating is formed on at least one outer surface of the porous channel sheet obtained in step 3) to obtain a conductive far-infrared sheet; the conductive coating is a composite conductive coating, which includes a base coating, a conductive network layer and a protective layer sequentially disposed on the outer surface of the porous channel sheet; the sheet resistance of the composite conductive coating is 20-60Ω / sq; 5) A conductive current-collecting area is formed on one side edge of the conductive far-infrared sheet obtained in step 4), and the conductive current-collecting area is electrically connected to the conductive coating; 6) Stack the conductive far-infrared sheets obtained in step 5) in multiple layers to form a continuous honeycomb channel between adjacent conductive far-infrared sheets; wherein, the conductive current-collecting area of ​​the odd-numbered conductive far-infrared sheets faces the first side of the honeycomb core, and the conductive current-collecting area of ​​the even-numbered conductive far-infrared sheets faces the second side of the honeycomb core, and the first side and the second side are two opposite sides of the honeycomb core. 7) Place the stacked conductive far-infrared sheets from step 6) into a limiting heat-bonding mold for local heat bonding. After cooling, trim the end face to obtain conductive far-infrared honeycomb filter material. The limiting heat-bonding mold has a limiting support part for limiting the compression deformation of the honeycomb channel.

2. The method of claim 1, wherein the conductive far infrared honeycomb filter is prepared by the steps of: In step 1), the thermoplastic resin is polypropylene or polyphenylene sulfide; when the thermoplastic resin is polypropylene, the far-infrared functional compound includes 70-85 parts of polypropylene, 8-20 parts of tourmaline powder, 0.2-1.0 parts of antioxidant, and 0.2-1.0 parts of lubricant; when the thermoplastic resin is polyphenylene sulfide, the far-infrared functional compound includes 60-75 parts of polyphenylene sulfide, 10-20 parts of tourmaline-zirconia composite powder, 10-20 parts of chopped glass fiber, and 1-5 parts of flame retardant. ​ In step 1), when the thermoplastic resin is polyphenylene sulfide, the polyphenylene sulfide is first dried at 120-150℃ for 3-5 hours, the far-infrared powder is dried at 100-120℃ for 1-3 hours, and then the polyphenylene sulfide, far-infrared powder and flame retardant are mixed and granulated by a twin-screw extruder. Short glass fibers are added through the side feed port of the twin-screw extruder to obtain high-temperature resistant far-infrared functional masterbatch. In step 7), when the thermoplastic resin is polypropylene, the local heat bonding temperature is 175-190℃, the pressure is 0.05-0.15MPa, and the holding time is 10-30s; when the thermoplastic resin is polyphenylene sulfide, the local heat bonding temperature is 285-305℃, the pressure is 0.08-0.20MPa, and the holding time is 15-40s.

3. The method of claim 1, wherein the electrically conductive far infrared honeycomb filter is prepared by the steps of: In step 4), before forming the conductive coating, the outer surface of the porous channel sheet is subjected to corona treatment, plasma treatment, or flame treatment. ​ 4. The method of claim 1, wherein the electrically conductive far infrared honeycomb filter is prepared by the steps of: The base coating is one of waterborne polyurethane base coating, waterborne chlorinated polypropylene base coating, waterborne chlorinated polypropylene-waterborne polyurethane composite base coating, and polyamide-imide base coating; the base coating contains a silane coupling agent and / or a carbodiimide crosslinking agent. ​ 5. The method of claim 1, wherein the electrically conductive far infrared honeycomb filter is prepared by the steps of: The conductive network layer is one of the following: graphene conductive layer, graphene-carbon nanotube conductive layer, graphene-antimony-doped tin dioxide conductive layer, graphene-carbon nanotube-antimony-doped tin dioxide ternary conductive network layer, and carbon nanotube-antimony-doped tin dioxide conductive layer. ​ 6. The method of claim 1, wherein the electrically conductive far infrared honeycomb filter is prepared by the steps of: The protective layer is one of the following: a siloxane-modified waterborne polyurethane protective layer, a fluorinated acrylic protective layer, a fluorinated siloxane-modified waterborne polyurethane conductive protective layer, and a siloxane-modified polyimide protective layer; the wet film thickness of the protective layer is 3-8 μm. ​ 7. The method of claim 1, wherein the electrically conductive far infrared honeycomb filter is prepared by the steps of: In step 5), the conductive busbar is formed by conductive carbon paste, conductive silver paste, conductive copper paste or metal foil strip. The width of the conductive busbar is 5-15 mm, the dry film thickness is 20-50 μm, and the sheet resistance is 5-15 Ω / sq. ​ 8. An electrically conductive far infrared honeycomb filter material, characterized by: Prepared by the method described in any one of claims 1-7.

9. The application of the conductive far-infrared honeycomb filter material as described in claim 8 in an air purification device, characterized in that: The air purification device includes a housing, a fan, a low-current high-voltage DC power supply, and a control module. The conductive far-infrared honeycomb filter material is installed inside the housing. The first metal busbar and the second metal busbar are respectively installed on the conductive busbar areas on opposite sides of the conductive far-infrared honeycomb filter material and are respectively connected to the low-current high-voltage DC power supply to form an electric field between adjacent conductive coatings. An insulating sealing layer, an insulating cover, or an insulating potting layer is provided between the first metal busbar and the second metal busbar to reduce the risk of surface creepage between the positive and negative electrodes. Dust-laden gas passes through the honeycomb channels of the conductive far-infrared honeycomb filter material under the action of the fan to achieve electric field-assisted capture of particulate matter. The operating voltage of the low-current high-voltage DC power supply is 3-8kV, and the output current is no more than 0.2mA; the passing wind speed of the dust-laden gas is 0.5-2.5m / s.

10. The application as described in claim 9, characterized in that: The applications are used for industrial ventilation and purification, welding fume treatment, oil mist exhaust gas treatment, grinding dust treatment, cutting fume treatment, pre-filtration of fresh air systems, or recirculating air purification.

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