Composite film-covered filter material with self-cleaning function and preparation method thereof

Abstract

The application discloses a composite film-coated filter material with self-dust cleaning function and a preparation method thereof. The composite film-coated filter material comprises, from inside to outside, a coarse fiber woven cloth layer, a medium fiber woven cloth layer or a non-woven cloth layer and a fine fiber cloth layer. The layers are combined by foam bonding, hot melt bonding or adhesive bonding. The mass of the composite material is 150-550 g / m 2 A polytetrafluoroethylene / nano-carbon film three-dimensional microporous membrane layer is coated or attached to the outer layer of the fine fiber woven cloth layer. The composite film-coated filter material with self-dust cleaning function produced by the application can omit the filter bag dust cleaning system in the high-temperature flue gas dust removal process of the steel, metallurgy, cement and waste incineration industries, shorten the process flow, greatly reduce the use amount of high-tech fibers, make waste resources, save costs, and complete the composite processing in one station with low liquid supply.

Description

Technical Field

[0001] This invention belongs to the field of filter material technology, and more specifically, relates to a composite membrane filter material with self-cleaning function and its preparation method. This filter material is suitable for high-temperature flue gas dust removal and filtration under different working conditions. Background Technology

[0002] In the field of air pollution control, electrostatic precipitators and baghouse (high-energy) dust collectors are the two most widely used types of high-efficiency dust removal equipment. Baghouse dust collectors have stable dust removal capabilities over a wide particle size range and have high dust removal efficiency for PM2.5 particles, thus they are widely used and have the fastest development.

[0003] Filter bags, made from filter media, are the core component of baghouse dust collectors. The main raw material is fiber material, with widely used types including aramid, aramid sulfone, polyphenylene sulfide (PPS), polyimide (P84), polytetrafluoroethylene (PTFE), ultrafine glass fiber, and basalt fiber (CBE). The manufacturing process of filter bags involves the following steps: 1. Long filaments or short fibers are woven into a base fabric; 2. Single or multiple fibers are mixed, carded, and laid into a web, then pre-needled and main-needled to form a nonwoven fabric; 3. The base fabric and nonwoven fabric are composited and reinforced to form a fiber felt; 4. The fiber felt is cut and sewn into filter bags.

[0004] A baghouse dust collector consists of main components including a dust-laden gas inlet, a clean air chamber, a housing, filter bags, pulse jet pipes, electromagnetic pulse valves, a dust hopper, a top cover, a support frame, a dust removal valve, and a purified gas outlet. Dust-laden flue gas gradually enters the fine fiber layer, base fabric, and coarse fiber layer from the surface of the filter bags, while clean flue gas exits from the inner layer. Surface filtration accumulates dust on the surface of the filter bags, forming a filter cake. When the pressure difference between the inner and outer layers of the filter bag reaches a certain level, the pulse valves are activated to clean the filter cake adhering to the surface of the filter bags using dry compressed air.

[0005] In the existing technology of needle punching loose fiber webs into nonwoven fabrics and base fabrics, and in the needle punching reinforcement process of nonwoven fabrics, as the needles move up and down at high speed, the needle tips and teeth will damage the base fabric and break the fiber web, resulting in a decrease in the strength of the filter media. The traditional dust removal concept advocates strong dust removal, which causes the filter cake on the surface of the filter bag to be excessively broken, making it difficult to settle and allowing fine particles to escape.

[0006] To address the shortcomings of existing technologies, the applicant previously invented "A Foam-Coated Composite High-Temperature Resistant Filter Material and Its Preparation Method," which has been granted patent number ZL201710480248.6. The foam-coated composite high-temperature resistant filter material represents a substantial improvement over needle-punched filter materials. The bonding of the base fabric layer and the upper and lower fiber web layers is changed from needle punching to the adhesion of the foam coating, avoiding damage or breakage to the base fabric and fibers caused by high-speed upward and downward piercing of the needles, thus preventing any impact on the filter material's strength. During foam coating, the coating agent is applied to the base fabric in the form of foams of varying sizes. As the foams burst, a discontinuous film is formed on the surface of the base fabric, thereby giving the filter material good air permeability and excellent filtration performance.

[0007] Foam-coated composite high-temperature resistant filter media is suitable for dust removal and filtration under various working conditions. However, its shortcomings include: the nonwoven fabric is still prepared using needle punching after the loose fibers are laid into a web, which has not completely solved the existing technical problems; during dust removal, fine particles and dust accumulate on the surface of the filter bag, and the filter cake is difficult to remove due to the high friction between the filter cake and the filter media surface, requiring strong external cleaning. However, this strong cleaning method can cause the filter cake to break, allowing fine particles to escape and making it difficult for them to settle.

[0008] The existing reinforcement technologies, filter cake removal technologies, and equipment for filter media are relatively outdated, which is a major factor restricting the development of the environmental filtration industry. Although existing technologies have provided a solution by changing the bonding of the base fabric layer and upper and lower fiber layers from needle punching to foam coating bonding, partially solving the technical problem of fiber breakage and base fabric damage caused by high-speed upward and downward piercing of the needles, thus affecting the strength of the filter media, they do not address the process defects of particle diffusion and difficulty in settling caused by deep and powerful dust removal. Summary of the Invention

[0009] This invention addresses the shortcomings of existing filter media by providing a composite membrane filter media with self-cleaning function.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned composite membrane filter material.

[0011] The objective of this invention is achieved through the following means:

[0012] A composite membrane filter material with self-cleaning function comprises, from the inside out, a coarse fiber woven fabric layer, a medium fiber woven fabric layer or a non-woven fabric layer, and a fine fiber fabric layer. The layers are bonded together using foam bonding, hot-melt bonding, or adhesive liquid bonding. The resulting composite material has a mass of 150-550 g / m³. 2 Then, a polytetrafluoroethylene / nanocarbon membrane three-dimensional microporous membrane layer is coated or adhered to the outer layer of the fine fiber fabric to form a composite membrane filter material; wherein, the thickness of the polytetrafluoroethylene / nanocarbon membrane three-dimensional microporous membrane layer is 0.1-0.6 mm, and the membrane mass is 20-80 g / m³.2 The aforementioned composite membrane filter media has a self-cleaning function.

[0013] Preferably, the polytetrafluoroethylene / nanocarbon membrane three-dimensional microporous membrane layer is made by incorporating nano-carbon black, nano-graphite powder and auxiliary additives into polytetrafluoroethylene nanopowder, mixing thoroughly and evenly, preparing it into a paste with a lubricant, and then forming it into strips, calendering, and finally performing a three-dimensional stretching process.

[0014] Preferably, the raw materials used in the fiber fabric layer are one or more short fibers or filaments selected from virgin or recycled carbon fiber, aramid, aramid sulfone, polyphenylene sulfide, polyimide, polytetrafluoroethylene, ultrafine glass fiber, and basalt fiber.

[0015] The preparation method of the above-mentioned composite membrane filter material with self-cleaning function specifically includes the following steps:

[0016] The layers are arranged from innermost to outermost as follows: coarse fiber woven layer, medium fiber woven layer or non-woven layer, fine fiber woven layer, and so on.

[0017] The fiber fabric layers are bonded into a composite material using a composite machine through foam bonding, hot melt bonding, or adhesive liquid bonding; finally, a three-dimensional microporous membrane layer of polytetrafluoroethylene / nanocarbon membrane is coated or pasted on the outer layer of the fine fiber fabric layer.

[0018] Preferably, the nonwoven fabric layer uses short fibers with a fineness of 1.5-7.5 dtex and a unit mass of 20-120 g / m². 2 .

[0019] The preparation method of the above-mentioned composite membrane filter material with self-cleaning function,

[0020] When using adhesive liquid for lamination, the upper and lower liquid supply rollers of the adhesive tank of the laminating machine are set as rubber rollers and steel rollers. The surface of the steel roller is engraved with patterns or irregular concave dots of different sizes. The steel roller is partially immersed in the adhesive liquid. The concave dots carry the adhesive liquid, and the steel rollers rotating in the same direction transfer the adhesive liquid to the fabric layer, so that the surface of the fabric layer forms dot-like adhesive and bonds it to other fabric layers.

[0021] When foam bonding is used, the adhesive liquid enters the foam generator from the adhesive liquid storage tank of the laminating machine. The resulting foam-like adhesive liquid is transported through pipelines to the foam baffle of the liquid supply roller in the adhesive liquid tank of the laminating machine. The liquid supply roller and the fabric layer rotate in the same direction, applying the foam adhesive liquid to the surface of the fabric layer. Under the action of the pressure roller, the foam bursts, and a discontinuous adhesive liquid is formed on the surface of the fabric layer. The resulting foam adhesive layer bonds the two fabric layers together.

[0022] The preferred method is to achieve the composite of multiple material layers through foam bonding, which can reduce the weight of the composite membrane filter material and lower the manufacturing cost.

[0023] When hot melt bonding is used, the two composite materials do not pass through the adhesive tank, but directly enter the heating box of the laminating machine. The heating roller temperature in the heating box reaches 200-230℃, so that the surface of the composite fiber layer is in a slightly molten state for bonding.

[0024] The preferred mass of the foam adhesive layer is 10-50 g / m³. 2 Preferred concentration: 15-30g / m 2 The thickness is 0.1-0.5mm, preferably 0.1-0.3mm.

[0025] Foam adhesive formulation: 35-45% polyacrylate emulsion; 5-12% titanium dioxide; 5-12% kaolin; 1-2% thickener; 1-2% crosslinking agent; 2-6% surface affinity agent; 0.1-0.6% waterproof and oil-repellent agent; 1-2% ammonia; 0.1-1% thermosetting adhesive; 20-40% water.

[0026] The foam adhesive liquid has a solid content of 40-65%, an application rate of 10-40 g / m², and a foam diameter of 0.1-5 mm.

[0027] The aforementioned hot-melt bonding relies on the characteristic that the surface of the composite layer fibers can slightly melt under heating, bonding them under a certain pressure. Preferably, the heating temperature for hot-melt bonding is 200-230℃, the bonding time is 5-15s, the cooling temperature is 5-15℃, and the cooling time is 20-80s. The thickness of the hot-melt bonded layer is 0.1-0.5mm, preferably 0.1-0.25mm. The mass of the composite material is 150-550g / m³. 2 Preferred concentration: 150-350g / m 2 .

[0028] Preferred adhesive formulation: 35-45% polyacrylate emulsion; 1-2% thickener; 1-2% crosslinking agent; 2-5% surface affinity agent; 40-60% water.

[0029] The preferred method for preparing the polytetrafluoroethylene / nanocarbon three-dimensional microporous membrane is as follows:

[0030] Carbon nanotubes, nano-carbon black, and nano-graphite are mixed into polytetrafluoroethylene (PTFE) nanopowder, along with one or two of these components, and multi-component excipients are added. The mixture is mechanically stirred to achieve uniform dispersion, then lubricated to form a paste. This paste is then formed into strips, calendered into sheets, and finally subjected to a three-dimensional stretching process. The amount of any one or two of the carbon nanotubes, nano-carbon black, and nano-graphite mixture added is 5-30% of the mass of the PTFE nanopowder; preferably, it is 10-20%. The multi-component excipients are dispersants, stabilizers, and nonionic surfactants in a mass ratio of 5:3:2, and are added at a rate of 1-2.5% of the mass of the PTFE nanopowder. All components of the excipients are micron-sized powders and can be uniformly dispersed in the mixed powder.

[0031] Preferably, the dispersant is PD-85, cyclohexanol, or dimethyl sulfoxide; the stabilizer is octyltin mercaptan or dioxane; and the surfactant is MPEG750 or sodium dodecyl sulfonate.

[0032] The thickness of the polytetrafluoroethylene / nanocarbon three-dimensional microporous membrane is preferably 0.2-0.4 mm, and the membrane mass is preferably 30-50 g / m³. 2 .

[0033] The number of layers in a multi-layer fabric composite can be determined based on process conditions and quality requirements for the filter media.

[0034] The multi-functional laminating machine comprises a two-story, double-layered front section, a body section, and a rear section, all constructed with a steel frame. On the ground level of the front section, four fabric rolling rollers are positioned along the machine's axis, with two viscous tanks placed between each pair of the first three rollers. The second floor of the steel frame houses the fifth fabric rolling roller, the third viscous tank, a viscous storage tank, and a foam generator. The body section is equipped with both heating and cooling systems. The rear section is the finished product winding area, containing one finished fabric winding roller. The front section houses a control cabinet, while the body and rear sections feature touchscreens for start / stop and temperature control.

[0035] The traditional process for producing filter media is as follows: Fiber A is woven into a base fabric using a shuttle loom, and fiber B or fiber C is mixed, carded, laid into a web, pre-needled, and then needle-punched into a nonwoven fabric; nonwoven fabrics made of fiber B or fiber C are laid on the base fabric woven from fiber A, and then reinforced by needle punching or hydroentangling to form the filter media.

[0036] Preferably, the process flow for producing the self-cleaning composite membrane filter material of the present invention is as follows: Coarse fiber A is woven into the first fabric layer using a shuttle loom or knitting machine; medium fiber B is woven into the third or fifth fabric layer or non-woven fabric layer using a shuttle loom, knitting machine, or non-woven fabric; fine fiber C is directly woven or spunbonded into a web, and then hot-pressed into the fifth or seventh woven or non-woven fabric layer. The first, third, and fifth fabric layers or non-woven fabric layers are bonded together using the second or fourth foam adhesive layer, or the fifth or seventh woven or non-woven fabric layer is bonded together using the fourth or sixth hot-melt adhesive layer to form a composite material. A nano-carbon membrane layer is coated on the surface of the fine fiber fabric layer of the composite material to form the composite membrane filter material.

[0037] The existing dust removal systems of bag filters in power plant boilers, metallurgical furnaces, and cement kilns rely on pulsed dry air to forcefully remove the filter cake accumulated on the surface of the filter bags, reducing the operating resistance within the system to a reasonable range. The process flow is as follows: fresh air—air storage tank—air source treatment (pressure regulation, condensation)—dryer—configuration system—air distribution manifold pulse valve—high-pressure pulse valve—filter bag surface, a complex procedure.

[0038] Composite membrane filter media can effectively achieve automatic dust removal due to the excellent microporous structure and porosity of the polytetrafluoroethylene (PTFE) microporous membrane, its relatively smooth surface, and good cake removal performance and filtration efficiency. Nano-carbon black and nano-graphite powder are excellent solid lubricants. The friction coefficient of the PTFE / nano-carbon three-dimensional microporous membrane is 30-50% lower than that of the PTFE biaxially oriented membrane, exhibiting good lubrication and coating properties on solid surfaces. The outermost layer of the composite PTFE nano-carbon membrane in the composite membrane filter media maximizes its lubrication effect. Dust accumulated on the surface of the nano-carbon membrane forms a filter cake of a certain thickness, which, after surface filtration, gradually detaches along the bag wall under increasing gravity, achieving automatic dust removal. Furthermore, the strength of this three-dimensional microporous membrane is more than twice that of ordinary biaxially oriented membranes.

[0039] Among the above-mentioned composite membrane filter media with self-cleaning function:

[0040] The woven fabric layer (coarse fiber, medium fiber, or fine fiber) can be woven or knitted, using single or multiple high-performance fiber filaments of varying thicknesses interwoven, or multiple high-performance fiber short fibers spun together, woven by machine or knit. The raw materials used can be one or more short fibers or filaments selected from virgin or recycled carbon fiber, aramid, aramid sulfone, polyphenylene sulfide, polyimide, polytetrafluoroethylene, ultrafine glass fiber, and basalt fiber. The choice of fiber material depends on environmental conditions and the requirements of the filter media. The fineness of the filaments should be 150-1200 dtex, preferably 150-600 dtex; the fineness of the staple fibers should be 1.5-7.5 dtex, preferably 1.50-4.5 dtex; the length should be 40-75 mm, preferably 50-75 mm; the fabric specifications should be: warp and weft density: 2-10 threads / cm, preferably 2-6 threads / cm, or a warp-weft interlining structure; the unit weight should be 25-200 g / m² of woven fabric. 2 Preferred size: 25-100g / m 2 Knitted fabric layer 20-100g / m 2 Preferred concentration: 30-50g / m 2 .

[0041] The nonwoven fabric layer is made of carbon fiber nonwoven fabric, which is formed by carding, web laying, hot pressing, and bonding of recycled carbon fiber, recycled filter fiber, or virgin high-tech fiber; or by melting, spinning, hot bonding, and hot pressing of high-strength, high-polymerization polymer. The short fiber fineness is 1.5-7.5 dtex, preferably 2.5-5.5 dtex, with a unit mass of 20-120 g / m³. 2 Preferred concentration: 20-60g / m 2The high-strength, high-polymerization-degree polymer can be polyethylene terephthalate or high-strength polyethylene, preferably polyethylene terephthalate.

[0042] The filter material needs to have a certain degree of air permeability. Conventional coating methods have poor air permeability. The key to the foam adhesive layer is to control the size and density of the foam. Foam of different sizes are squeezed to form a discontinuous film on the surface of the fabric layer, which makes the composite material breathable.

[0043] Preferably, the preparation of the three-dimensional microporous membrane composite coated filter material is as follows:

[0044] The lamination of multi-layered materials and the coating of three-dimensional microporous membranes are carried out on a multi-functional laminating machine. The multi-functional laminating machine consists of a two-story, double-layered front section, a body section, and a rear section, all constructed with a steel frame. On the ground level of the front section, four fabric rolling rollers are placed along the machine's axis, with a viscous trough positioned between each pair of the first three rollers. The second floor of the steel frame houses the fifth fabric rolling roller, the third viscous trough, a viscous storage tank, and a foam generator. The body section is equipped with both heating and cooling systems. The rear section is the finished product winding area, containing one finished fabric winding roller. The front section houses a control cabinet, while the body and rear sections have touchscreens for start / stop and temperature control. The front section also includes a crane for hoisting the fabric rolling rollers.

[0045] The lamination process is as follows: When using adhesive liquid for lamination, the upper and lower feed rollers of the laminating machine's adhesive tank are rubber rollers and steel rollers with patterns or concave dots engraved on their surfaces. The adhesive liquid in the adhesive storage tank is directly transported to the adhesive tank through pipelines, immersing part of the lower feed roller in the adhesive tank so that the surface of the feed roller is coated with adhesive liquid. The liquid-feeding roller and the fabric layer rotate in the same direction, applying the dotted adhesive from the lower liquid-feeding roller to the front or back of the fabric layer. Under the action of the pressure roller, the multiple fabric layers are bonded together. When using the foam coating process, the adhesive liquid enters the foam generator from the storage tank. The resulting foam-like adhesive liquid is transported through a pipeline to the foam baffle of the liquid-feeding roller in the adhesive tank. The liquid-feeding roller and the fabric layer rotate in the same direction, applying the foam adhesive liquid to the surface of the fabric layer. Under the action of the pressure roller, the foam bursts, and discontinuous adhesive liquid is formed on the surface of the fabric layer, thus bonding the two fabric layers together. When using the hot melt bonding process, the two fabric layers to be laminated do not pass through the adhesive tank and directly enter the heating box of the multi-functional laminating machine. The heating roller temperature in the heating box reaches 200-230℃, so that the surface of the composite layer fibers is in a slightly molten state.

[0046] This invention employs a specific multifunctional composite method to complete the composite coating process of multilayer fiber materials and three-dimensional microporous membranes in one step.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1. The composite membrane filter material with self-cleaning function produced by this invention eliminates the traditional concept of needle-punching and reinforcing filter materials with base cloth and fiber mesh, and completely solves the technical problem that has plagued the filtration industry by causing the fibers to be damaged twice, affecting the strength of the filter material.

[0049] 2. By using the self-cleaning composite membrane filter material of the present invention, the filter bag cleaning system can be eliminated in the high-temperature flue gas dust removal process of industries such as steel, metallurgy, cement and waste incineration, thereby shortening the process and reducing maintenance and investment costs.

[0050] 3. The preparation method of this invention can significantly reduce the amount of high-tech fibers used, save costs, make waste resources, and complete composite processing in one stop with low liquid supply, which is in line with the "green manufacturing" development model. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the cross-sectional structure of the composite membrane filter media.

[0052] In the figure, 1 is the coarse fiber fabric layer, 2 is the first layer of foam adhesive, 3 is the medium fiber fabric layer or non-woven fabric layer, 4 is the second layer of foam adhesive, 5 is the fine fiber fabric layer, 6 is the third layer of hot melt adhesive or adhesive layer, and 7 is the polytetrafluoroethylene / nano carbon microporous membrane layer.

[0053] Figure 2 This is a schematic diagram of a filter bag dust collector.

[0054] In the diagram, 8 is the dust-laden gas inlet, 9 is the purified gas outlet, 10 is the top cover, 11 is the clean air chamber, 12 is the blow nozzle, 13 is the solenoid pulse valve, 14 is the filter bag, 15 is the ash hopper, and 16 is the ash discharge valve.

[0055] Figure 3 SEM image of the microstructure of polytetrafluoroethylene / carbon nanoporous membrane;

[0056] Figure 4 A visual representation of the surface layer of dust-laden polytetrafluoroethylene / nanocarbon membrane filter media;

[0057] Figure 5 This is a schematic diagram of the structure of a multi-functional composite machine;

[0058] Figure 6 A schematic diagram showing the connection between the viscous conveying structure of the multi-functional laminator and the viscous tank and foam baffle.

[0059] Figure 7 This is a schematic diagram of the heating box of a multi-functional composite machine. Detailed Implementation

[0060] The present invention will be further explained and illustrated below through specific embodiments:

[0061] In the embodiments, the coarse, medium, and fine fiber fabric layers and the three-dimensional microporous membrane were provided by Jiangsu Huayue Textile New Material Technology Co., Ltd., the knitted fabric layer was provided by Jiangsu Shuangshan Group, and the nonwoven fabric layer was provided by Jiangsu Fumeisi Environmental Protection and Energy Saving New Material Co., Ltd. The multi-functional composite machine was manufactured by Jiangsu Huayue Textile New Material Technology Co., Ltd., and the adhesives, auxiliaries, and other chemical agents are commercially available. Example 1

[0062] The preparation of composite membrane filter media with self-cleaning function includes the following steps:

[0063] 1. Multilayer composite materials consist of the following fabric layers:

[0064] Coarse fiber layer: Fiber material: alkali-free glass fiber yarn, fineness 800 dtex; Weaving method: knitted; Fabric structure: warp-knitted weft-inserted structure; Weight: 85 g / m 2 Thickness: 0.25mm.

[0065] Medium fiber layer: Fiber material: polyimide fiber yarn, fineness 300 dtex; Weaving method: machine weaving; Fabric structure specifications: warp density 4 threads / cm, weft density 4 threads / cm; Weight: 100 g / m 2 Thickness: 0.22mm.

[0066] Fine fiber layer: Fiber material: polytetrafluoroethylene film split fiber, fineness 200 dtex; Weaving method: machine weaving; Fabric structure specifications: warp density 10 threads / cm, weft density 6 threads / cm; Weight: 80 g / m 2 Thickness: 0.20mm. Fabric width of coarse, medium and fine fiber layers: 1.6m.

[0067] 2. Preparation of polytetrafluoroethylene / nano carbon black three-dimensional microporous membrane:

[0068] Nano-polytetrafluoroethylene (PTFE) powder and nano-carbon black powder are mixed at a ratio of 85:15 and stirred at a low speed of 50 rpm for 50 minutes. Then, 1.5% (by weight of the PTFE nano-powder) of auxiliary materials are added, and the mixture is stirred at low speed for another 30 minutes. The auxiliary materials include dispersant cyclohexanol, stabilizer thiol octyltin, and surfactant MPEG750, with a mass ratio of 50:30:20. Aviation kerosene (17% by weight of the PTFE powder) is added to the above mixed powder and stirred until a paste is formed. The paste is then formed into strips, calendered into sheets, and three-dimensionally stretched to create a microporous membrane. The PTFE / nano-carbon black microporous membrane has a mass of 50 g / m³. 2 The thickness is 0.25mm.

[0069] 3. Preparation of composite membrane filter media

[0070] The composite membrane filter media is laminated on a multi-functional laminating machine. The coarse, medium, and fine fiber fabric layers and the polytetrafluoroethylene / nano carbon black three-dimensional microporous membrane layer prepared above are placed on the first roll roller 17, the second roll roller 18, the third roll roller 19, and the fifth roll roller 21 of the multi-functional laminating machine, respectively. The first viscous tank 22, the second viscous tank 25, and the third viscous tank 28 are all bonded with foam adhesive. The fiberglass fabric layer and polyimide fabric layer on the first roll roller 17 and the second roll roller 18 rotate clockwise and are bonded at the first liquid supply roller 23 and the second liquid supply roller 24 above the first viscous trough 22. The composite material is guided to the second viscous trough 25 liquid supply roller by the guide roller and is bonded to the counterclockwise rotating polytetrafluoroethylene fabric layer for a second time. The three-layer composite material is guided to the third viscous trough 28 liquid supply roller and is bonded to the counterclockwise rotating polytetrafluoroethylene / nano carbon black microporous membrane for a third time. The resulting four-layer fiber material and nano carbon black microporous membrane composite filter material enters the heating box 41 through the second two-roll rolling mill 49 and the third two-roll rolling mill 50. It is heated by the first heating roller 42 and the second heating roller 43 to remove moisture. After drying, it enters the cooling zone through the fourth two-roll rolling mill 51 for cooling. The cooled membrane composite filter material is wound into a shaft by the finished roll roller 52.

[0071] Foam adhesive formulation: 42% polyacrylate emulsion; 9% titanium dioxide; 9% kaolin; 1.2% PF thickener; 1.4% crosslinking agent L; 2.2% surface affinity agent P; Unien TG5263; 0.5% waterproof and oil-repellent agent; 1.3% ammonia; 0.6% thermosetting adhesive A651-20; the remainder is water. The foam adhesive has a solids content of 40% and an application rate of 15g / m². 2 Thickness 0.12mm, foam density 30g / l, foaming ratio 1:5, foam diameter 0.1-5mm.

[0072] Composite processing technology: speed 15 m / min, two-roll mill pressure 4.5 MPa, heating box temperature 130℃, cooling temperature 15℃, width 1.6 m.

[0073] 4. Quality test results of composite membrane filter media:

[0074] Weight (g / cm²): 350, Thickness (mm): 1.04, Tensile Strength (N / 5χ20cm): Longitudinal: 1224, Transverse: 1310, Elongation at Break (%): Longitudinal: 1.2, Transverse: 1.4, Air Permeability (m²) 3 / m 2 / min): 85, surface friction coefficient: 0.13. Example 2

[0075] The preparation of composite membrane filter media with self-cleaning function includes the following steps:

[0076] 1. Multilayer composite materials consist of the following fabric layers:

[0077] Coarse fiber layer: Fiber material: polyphenylene sulfide fiber yarn, fineness 600 dtex; Weaving method: machine weaving; Fabric structure specifications: warp density 4 / cm, weft density 6 / cm; Weight: 80 g / m 2 Thickness: 0.20mm.

[0078] Fine fiber layer: Fiber material: polytetrafluoroethylene film split filament, fineness 200 dtex; Weaving method: machine weaving; Fabric structure specifications: warp density 8 threads / cm, weft density 6 threads / cm; Weight: 70 g / m 2 Thickness: 0.12mm.

[0079] Nonwoven fabric layer: Fiber material: recycled carbon fiber / high-strength polyester spunbond nonwoven fabric; fineness 1.5D; weight: 60g / m 2 Thickness: 0.15mm.

[0080] 2. Preparation of polytetrafluoroethylene / nanographite three-dimensional microporous membrane

[0081] Nano-polytetrafluoroethylene (PTFE) powder and nano-graphite powder were mixed at a ratio of 83:17 and stirred at a low speed of 50 rpm for 60 minutes. Then, 1.4% (by weight of the PTFE nano-powder) of auxiliary materials were added, and the mixture was stirred at low speed for another 30 minutes. The auxiliary materials included dispersant cyclohexanol, stabilizer thiol octyltin, and surfactant MPEG750, with a mass ratio of 50:30:20. Aviation kerosene (20% by weight of the PTFE nano-powder) was added to the mixed powder and stirred until a paste was formed. The paste was then formed into strips, calendered into sheets, and three-dimensionally stretched to produce a PTFE / nano-graphite microporous membrane. The membrane mass was 45 g / m³. 2 The thickness is 0.20mm.

[0082] 3. Preparation of composite membrane filter media

[0083] The composite membrane filter media is laminated on a multi-functional laminating machine. The above-mentioned polyphenylene sulfide fiber fabric layer, polyimide fiber fabric layer, polytetrafluoroethylene fiber fabric layer, recycled carbon fiber / high-strength polyester spunbond nonwoven fabric layer, and three-dimensional microporous membrane layer are respectively placed on the first roll roller 17, the second roll roller 18, the third roll roller 19, and the fifth roll roller 21 of the multi-functional laminating machine. The first viscous tank 22, the second viscous tank 25, and the third viscous tank 28 are all bonded with foam adhesive. The polyphenylene sulfide (PPS) fiber fabric layer on the first roll of fabric 17 enters the first liquid-feeding roller 23 of the first viscous trough 22 clockwise, and then passes through the second liquid-feeding roller 24, where foam viscous is applied to the PPS fiber fabric layer. The medium-fiber fabric layer on the second roll of fabric 18 rotates counterclockwise and enters the first liquid-feeding roller 23 for two-layer material bonding, and is then guided to the third liquid-feeding roller 26 of the viscous trough 25 via a guide roller. The fine-fiber fabric layer on the roll of fabric 19 rotates counterclockwise to the fourth liquid-feeding roller 27 of the second viscous trough 25 for three-layer material bonding, and is then guided to the fifth liquid-feeding roller 29 of the third viscous trough 28 via a guide roller. The recycled carbon fiber / polyester spunbond nonwoven fabric layer on the fourth roll of fabric 20 rotates counterclockwise to the third viscous trough 28. The first movable foam baffle 35 of the fifth liquid supply roller 29 is combined with the three-layer composite material, and then introduced into the second two-roller trolley 49. The nano-graphite microporous membrane on the fourth roll roller 20 rotates clockwise and is combined with the four-layer composite material in the second two-roller trolley 49. It enters the heating box 41 through the third two-roller trolley 50. The five-layer composite material is dried by the first heating roller 42 and the second heating roller 43 to remove moisture. Then it is heated to 220-230℃ by the third heating roller 44, the fourth heating roller 45 and the fifth heating roller 46, so that the surface of the fiber layer melts and the nano-graphite microporous membrane is bonded. It enters the cooling zone for cooling through the fourth two-roller trolley 51, and the finished roll roller 52 rolls it up.

[0084] In the preparation process, foam bonding is used between the fiber fabric layers; bonding is used between the fabric layers and the nonwoven fabric layers; and hot-melt bonding is used between the nonwoven fabric layers and the polytetrafluoroethylene / nanographite microporous membrane. During the bonding process, a pair of rollers above the 28-slip tank are a rubber roller and a steel roller, respectively. The concave dots engraved on the surface of the steel roller are 5 mm apart and 2 mm deep.

[0085] Foam adhesive formulation: 45% polyacrylate emulsion; 5% titanium dioxide; 5% kaolin; 1.4% PF thickener; 1.1% crosslinking agent L; 2.4% surface affinity agent P; 0.4% Unien TG5263 waterproof and oil-repellent agent; 1.4% ammonia; 37.6% water. Adhesive layer formulation: 48% polyacrylate emulsion; 2.2% thickener; 10.8% crosslinking agent; 4.7% surface affinity agent P; 2.4% ammonia; the remainder is water.

[0086] Foam generator: Foam density: 50 g / L, expansion ratio: 1:5, foam diameter: 0.5-4.5 mm, adhesive layer thickness: 0.4 mm. Foam application rate: 15 g / m², solids content: 55%. Adhesive liquid application rate: 20 g / m². 2 It has a solid content of 52% and a thickness of 0.12 mm.

[0087] Adhesive formulation: 40% polyacrylate emulsion, 1.5% thickener PF, 1.6% crosslinking agent L, 2.4% surface affinity agent P, and the remainder is water. The adhesive has a solids content of 60%, an application rate of 15 g / m², and a thickness of 0.12 mm.

[0088] Composite process: speed 15 m / min, two-roll rolling pressure 4.5 MPa, heating rolls 42 and 43 in the heating box at 130℃, heating rolls 44, 45 and 46 at 300℃±5℃, cooling temperature 15℃, width 1.6m.

[0089] 4. Quality test results of composite membrane filter media:

[0090] Weight (g / cm²): 330, Thickness (mm): 0.93, Tensile Strength (N / 5χ20cm): Longitudinal: 1310, Transverse: 1520, Elongation at Break (%): Longitudinal: 1.1, Transverse: 1.3, Air Permeability (m³ / s) 3 / m 2 / min): 80, surface friction coefficient: 0.12. Example 3

[0091] like Figure 5-7 As shown, the structure of the multi-functional laminating machine used in Examples 1 and 2 for multi-layer fabric lamination is as follows:

[0092] The front section has a two-layered structure. On the ground layer, along the axial direction of the multi-functional laminating machine, are arranged a first fabric roll shaft 17, a second fabric roll shaft 18, a third fabric roll shaft 19, and a fourth fabric roll shaft 20. On the second layer, a fifth fabric roll shaft 21 is placed. A first viscous trough 22 is placed between the first and second fabric roll shafts 17 and 18, and a first and second liquid-feeding rollers 23 and 24 are positioned above it. A second viscous trough 25 is placed between the second and third fabric roll shafts 18 and 19, and a third and fourth liquid-feeding rollers 26 and 24 are positioned above it. 27. A third viscous trough 28 is provided on one side of the feed direction of the fifth roll roller 21. A fifth liquid feeding roller 29 and a sixth liquid feeding roller 30 are arranged above the third viscous trough 28. A first foam baffle 31, a second foam baffle 32, a third foam baffle 33 and a fourth foam baffle 34 are respectively provided on one side of the first liquid feeding roller 23, the second liquid feeding roller 24, the third liquid feeding roller 26 and the fourth liquid feeding roller 27. A first movable foam baffle 35, a second movable foam baffle 36, a third movable foam baffle 37 and a fourth movable foam baffle 38 are respectively provided on both sides of the fifth liquid feeding roller 29 and the sixth liquid feeding roller 30.

[0093] The mucus delivery structure is connected to all mucus tanks, all foam baffles, and all movable foam baffles.

[0094] The vehicle body is a box structure, which includes a heating box 41 and five internal heating rollers, namely the first heating roller 42, the second heating roller 43, the third heating roller 44, the fourth heating roller 45 and the fifth heating roller 46. The discharge end of the vehicle head is connected to the feed end of the vehicle body.

[0095] At the rear of the vehicle, the feeding end is connected to the discharge end of the vehicle body. The rear of the vehicle includes multiple cooling rollers, which form a cooling system 47. The discharge end of the rear of the vehicle is connected to the finished fabric roll roller 52.

[0096] The first two-roller rolling mill 48 is placed in the gap between the two layers of fabric rolling rollers, the second two-roller rolling mill 49 and the third two-roller rolling mill 50 are placed at the feeding end of the body part, and the fourth two-roller rolling mill 51 is placed at the discharge end of the body part.

[0097] The movable foam baffles on both sides of the fifth liquid supply roller 29 and the sixth liquid supply roller 30 are arranged in an inverted octagon shape.

[0098] The sludge conveying structure includes a sludge storage tank 39 and a foam generator 40. The first outlet of the sludge storage tank 39 is connected to the first sludge tank 22, the second sludge tank 25 and the third sludge tank 28. The second outlet of the sludge storage tank 39 is connected to all the foam baffles and all the movable foam baffles through the foam generator 40.

[0099] In this embodiment, the first liquid supply roller 23 and the second liquid supply roller 24 are a rubber roller and a steel roller, respectively, and the outer surface of the steel roller is uneven. The liquid supply roller above each viscous trough can be configured with the same structure as the first liquid supply roller 23 and the second liquid supply roller 24.

[0100] It also includes the control panel and transmission components that are positioned opposite each other.

[0101] The walls of the first slime tank 22, the second slime tank 25, and the third slime tank 28 are all sandwich structures made of stainless steel, and heating tubes are installed inside the jacket.

[0102] The side walls of the body box are made of double-layer metal plates, with an insulation layer filling the space between the metal plates.

[0103] All heating rollers rotate in the same direction, while all cooling rollers rotate in different directions.

[0104] In summary, the multi-functional composite machine for multi-layer fabric composite processing is 21m long, with the front, body, and rear sections measuring 8m, 8m, and 5m respectively; the working width is 3.5m, and the effective processing width is 2.5m; the ground floor height of the front section is 2.5m, and the second floor height is 2.5m; the floor slabs of both layers are made of patterned steel plates, and the steel frame, heating box 41, and cooling box of the front section are all made of channel steel. The body of the heating box 41 is made of insulated steel sheet, and an aerogel insulation layer is filled between the two steel plates. When the first viscous tank 22 is coated using a full coating process, the fabric layer to be laminated will adhere the viscous liquid adhering to the surface of the first liquid roller 23 in the first viscous tank 22 to the back of the fabric layer when it comes into contact with the first liquid roller 23. This will then laminate with another fabric layer that enters in the same direction. In the full coating process, the first foam baffle 31 and the second foam baffle 32 do not function. When a foam coating process is used, the viscous liquid in the viscous storage tank 39 passes through the foam generator 40. The resulting foam is directly transported through pipes to the upper liquid roller and the lower foam baffle or movable foam baffle. In the foam coating process, the viscous tank is always empty.

[0105] The fifth roll of fabric 21 in the head section is positioned not only for multi-layer material composites, but also for bonding a polymer film to the outermost layer of the composite material, enabling the film to impart more properties to the multi-layer composite material.

Claims

1. A method for preparing a composite membrane filter material with self-cleaning function, characterized in that... The method specifically includes the following steps: From the inner layer to the outer layer, a coarse fiber woven layer, a medium fiber woven layer or a non-woven layer, and a fine fiber woven layer are sequentially bonded into a composite material using a laminating machine via foam bonding, hot melt bonding, or adhesive liquid bonding; finally, a polytetrafluoroethylene / nanocarbon membrane three-dimensional microporous membrane layer is coated or pasted onto the outer layer of the fine fiber woven layer; when using adhesive bonding, the upper and lower liquid-feeding rollers of the laminating machine's viscous liquid tank are rubber rollers and steel rollers with patterns or concave dots engraved on their surfaces. The adhesive liquid in the viscous liquid storage tank is directly transported to the viscous liquid tank through a pipeline. The lower liquid-feeding roller is partially immersed in the viscous liquid tank, so that the surface of the liquid-feeding roller is coated with adhesive liquid. The liquid-feeding roller and the fabric layer rotate in the same direction, applying the dotted adhesive liquid on the lower liquid-feeding roller to the fabric. On either the front or back of the layer, under the action of pressure rollers, the multi-layer fabric layers are bonded together. When using a foam coating process, the adhesive liquid enters the foam generator from the storage tank. The resulting foam-like adhesive liquid is transported through pipes to the foam baffle of the liquid supply roller in the adhesive tank. The liquid supply roller and the fabric layer rotate in the same direction, applying the foam adhesive liquid to the surface of the fabric layer. Under the action of pressure rollers, the foam bursts, and a discontinuous adhesive liquid is formed on the surface of the fabric layer, thus bonding the two fabric layers together. When using a hot melt bonding process, the two fabric layers to be laminated do not pass through the adhesive tank and directly enter the heating box of the multi-functional laminating machine. The temperature of the heating roller in the heating box reaches 200-230℃, so that the surface of the composite layer fibers is in a slightly molten state. The self-cleaning composite membrane filter material comprises, from the inside out, a coarse fiber woven fabric layer, a medium fiber woven fabric layer or a non-woven fabric layer, and a fine fiber fabric layer. The layers are bonded together using foam bonding, hot-melt bonding, or adhesive liquid bonding. The resulting composite material has a mass of 150-550 g / m³. 2 Then, a polytetrafluoroethylene / nanocarbon membrane three-dimensional microporous membrane layer is coated or adhered to the outer layer of the fine fiber fabric to form a composite membrane filter material; wherein, the thickness of the polytetrafluoroethylene / nanocarbon membrane three-dimensional microporous membrane layer is 0.1-0.6 mm, and the membrane mass is 20-80 g / m³. 2 ; The polytetrafluoroethylene / nanocarbon three-dimensional microporous membrane is prepared as follows: The process involves incorporating one or two of the following into polytetrafluoroethylene (PTFE) nanopowder: carbon nanotubes, nano-carbon black, and nano-graphite. Multiple auxiliary materials are added, and the mixture is mechanically stirred to achieve uniform dispersion. A lubricant is used to prepare a paste, which is then formed into strips, calendered into sheets, and finally subjected to a three-dimensional stretching process. The amount of any one or two of the following—carbon nanotubes, nano-carbon black, and nano-graphite—added is 5-30% of the mass of the PTFE nanopowder. The multiple auxiliary materials are a dispersant, stabilizer, and nonionic surfactant in a mass ratio of 5:3:2, and the amount added is 1-2.5% of the mass of the PTFE nanopowder.

2. The method for preparing the composite membrane filter material with self-cleaning function according to claim 1, characterized in that... The raw materials used in the fiber fabric layer are one or more short fibers or filaments selected from virgin or recycled carbon fiber, aramid, aramid sulfone, polyphenylene sulfide, polyimide, polytetrafluoroethylene, ultrafine glass fiber, and basalt fiber.

3. The method for preparing the composite membrane filter material with self-cleaning function according to claim 1, characterized in that... The nonwoven fabric layer uses short fibers with a fineness of 1.5-7.5 dtex and a unit mass of 20-120 g / m². 2 .

4. The method for preparing the composite membrane filter material with self-cleaning function according to claim 1, characterized in that... The foam adhesive liquid has a solid content of 40-65% and an application rate of 10-40 g / m³. 2 The foam diameter is 0.1-5mm.

5. The method for preparing the composite membrane filter material with self-cleaning function according to claim 1, characterized in that... The hot melt adhesive uses a heating temperature of 200-230℃, a hot bonding time of 5-15s, a cooling temperature of 5-15℃, and a cooling time of 20-80s.

6. The method for preparing the composite membrane filter material with self-cleaning function according to claim 1, characterized in that... The dispersant is PD-85, cyclohexanol, or dimethyl sulfoxide; the stabilizer is octyltin mercaptan or dioxane; and the surfactant is MPEG750 or sodium dodecyl sulfonate.

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