Mixed conductive dust removal filter bag and preparation method thereof

Abstract

The invention discloses a mixed conductive dust removal filter bag and a preparation method, and relates to the technical field of filter bags. According to the mixed conductive dust removal filter bag, the filter bag is formed by sewing a mixed conductive fiber needled felt, the mixed conductive fiber needled felt comprises polyester fibers and conductive fibers which are uniformly blended, and the conductive fibers form a three-dimensional network-shaped continuous conductive path in the needled felt; the gram weight of the mixed conductive fiber needled felt is 500-600 g / m, and the thickness of the mixed conductive fiber needled felt is 1.8-2.0 mm. According to the mixed conductive dust removal filter bag and the preparation method, the micron-sized conductive fibers and the polyester fibers are uniformly blended in the raw material stage, so that the conductive fibers become inherent structural components of a filter material, and the conductive fibers are stable in chemical property, insoluble in water and resistant to corrosion, so that the antistatic performance of the conductive fibers is as long as that of the filter material and is durable and not attenuated; the micro conductive fibers are mutually lapped in a three-dimensional space of the filter material to form a continuous and three-dimensional conductive path.

Description

Technical Field

[0001] This invention relates to the field of filter bag technology, and in particular to a mixed-conductivity dust removal filter bag and its preparation method. Background Technology

[0002] In high-dust-concentration environments such as cement, metallurgy, chemical, and coal-fired power generation, dust and filter bag fibers experience intense friction during high-speed filtration and cleaning, easily generating and accumulating large amounts of static electricity. To address this static electricity problem, existing technologies mainly employ two approaches: one is the post-treatment antistatic agent method, where antistatic agents are mostly hydrophilic or organic polymers. Under high temperatures, corrosive gases, or repeated mechanical cleaning (such as pulse jet cleaning), these agents are prone to volatilization, decomposition, or wear, leading to rapid and irreversible degradation of antistatic performance, failing to meet the requirements for long-term stable operation. The second approach is the method of embedding conductive yarns into the base fabric. The conductive pathways are distributed in a discrete grid, but the lack of conductive fibers in the inter-grid areas still easily leads to localized static electricity accumulation and uneven protection. The coarse and stiff conductive yarns may affect the overall flexibility and filtration uniformity of the filter media. Under the stress of long-term pulse jet cleaning, the interlacing points of the conductive yarns and the base fabric are prone to wear or breakage, causing the conductive network to fail. This invention aims to provide a solution based on fiber-level uniform blending and the construction of a three-dimensional conductive network. Summary of the Invention

[0003] The purpose of this invention is to provide a hybrid conductive dust removal filter bag and its preparation method. By uniformly blending micron-sized conductive fibers with polyester fibers in the raw material stage, the conductive fibers become an inherent structural component of the filter material, which is durable and does not decay, thereby solving the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a mixed conductive dust collector filter bag, wherein the filter bag is made of mixed conductive fiber needle-punched felt, the mixed conductive fiber needle-punched felt comprising uniformly blended polyester fibers and conductive fibers, wherein the conductive fibers form a three-dimensional network of continuous conductive pathways in the needle-punched felt; the mixed conductive fiber needle-punched felt has a basis weight of 500-600 g / m², a thickness of 1.8-2.0 mm, and a surface resistivity ≤5.0×10⁻⁶. 9 Ω, volume resistivity ≤9.9×10 9 Ω.

[0005] Preferably, the conductive fiber is stainless steel or corrosion-resistant alloy metal fiber, and the diameter of the conductive fiber is 6-8 micrometers.

[0006] Preferably, the conductive fiber accounts for 0.5%-5% of the total mass of all fibers in the mixed conductive fiber needle-punched felt, and all fibers are the sum of polyester fibers and conductive fibers.

[0007] Preferably, the breaking strength of the mixed conductive fiber needle-punched felt meets the following requirements: warp ≥ 1100N (5*20cm), weft ≥ 1300N (5*20cm).

[0008] Preferably, the air permeability of the hybrid conductive fiber needle-punched felt is 13-16 m³ / (m²·min), the average value of the triboelectric potential is ≤185V, and the surface charge density is ≤2.37×10⁻ 8 C / m².

[0009] Preferably, the continuous operating temperature of the mixed conductive fiber needle-punched felt is 120°C, and the instantaneous withstand temperature is 150°C.

[0010] Another technical problem to be solved by the present invention is to provide a method for preparing a mixed-conductivity dust collector filter bag, comprising the following steps:

[0011] S1: Open and mix polyester fibers and conductive fibers in a certain proportion;

[0012] S2: The mixed fibers are combed and laid into a web to form a fiber web;

[0013] S3: The fiber web is stacked with the filament base fabric and needle-punched to make the fibers and base fabric entangled to form a needle-punched felt fabric with a three-dimensional conductive network.

[0014] S4: Post-finishing of needle-punched felt fabric;

[0015] S5: The finished needle-punched felt is sewn into a dust removal filter bag.

[0016] Preferably, in step S3, the needling is completed in two steps: pre-needling and main needling, and the total needling density is 350-450 needles / square centimeter, which gradually strengthens the structure without damaging it.

[0017] Preferably, the finishing process in step S4 includes at least heat setting, and also includes one or more of singeing, calendering and Teflon coating treatment.

[0018] Preferably, in step S5, antistatic sewing thread is used for sewing, and after sewing is completed, the overall conductivity of the filter bag is checked and ensured by measuring the resistance between any two points on the filter bag.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a hybrid conductive dust collector filter bag and its preparation method, which uniformly blends micron-sized conductive fibers with polyester fibers in the raw material stage, making the conductive fibers an inherent structural component of the filter material. The conductive fibers are chemically stable, insoluble in water, and corrosion-resistant, so their antistatic performance has the same lifespan as the filter material and does not decay over time. The micro-conductive fibers overlap each other in the three-dimensional space of the filter material to form a continuous and three-dimensional conductive path, which makes any point on the surface and inside of the filter material have excellent charge dissipation ability, and the surface resistance and volume resistance can be stably controlled within the safe conductive range. By integrating uniform blending and precision needle punching processes, the prepared hybrid conductive needle punched felt has high mechanical strength, suitable air permeability, and ideal thickness, overcoming the defects of traditional mesh conductive methods where coarse and stiff conductive yarns may damage the flexibility and strength of the filter material. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the tables in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: A mixed conductive dust collector filter bag and its preparation method.

[0022] The filter bags are made of the following raw materials: 1.5 dtex × 38 mm conventional polyester staple fiber and 316L stainless steel conductive staple fiber with a diameter of 7 μm and a length of 38 mm. The conductive fiber accounts for 1.5% of the total fiber (polyester + conductive fiber) mass. The base fabric is 75 g / m². 2 Polyester filament woven fabric.

[0023] The filter bags are manufactured using the following process:

[0024] Add the two types of fibers into the opening mixer according to the above ratio, and mix thoroughly until the conductive fiber monofilaments are evenly dispersed.

[0025] After being carded by a carding machine, the fibers are cross-laid to form a uniform fiber web;

[0026] The fiber web is layered with the base fabric and pre-punched, with a punching density of 120 needles / cm. 2 Then perform the main puncture, with a needle density of 280 needles / cm². 2 The total needle density is 400 needles / cm². 2 The depth of the needle and the needle shape are matched to ensure that the fibers are fully entangled without being over-compacted;

[0027] First, heat setting is performed at 200℃ and 5m / min to stabilize the structure. Then, singeing is performed to burn off the surface hairs and make the filter material surface smooth.

[0028] Using antistatic sewing thread embedded with carbon fiber, the body, opening, and bottom of the treated needle-punched felt are sewn together to form a filter bag with a diameter of Φ160×6000mm. After sewing, a resistance tester conforming to GB / T 12703.4-2010 or EN 1149 is used to measure the resistance between any two points on the filter bag. The filter bag is considered safe when the measured resistance value is stable and less than 1.0×10⁻⁶. 10 When the value is Ω, it can be determined that the filter bag has good electrical continuity.

[0029] The resistance between the metal ring at the bag opening and the center of the bag bottom was measured to be 5.6 × 10⁻⁶. 8 Ω indicates excellent overall conductivity continuity.

[0030] Performance testing: Samples of the manufactured needle-punched felt were tested, and the results are as follows:

[0031] Weight: 535 g / m 2

[0032] Thickness: 1.85 mm

[0033] Fracture strength: 1180 N (5*20cm) in the warp direction, 1380 N (5*20cm) in the weft direction.

[0034] Breathability: 15.2 m 3 / (m 2 ·min)

[0035] Surface resistivity: 3.8 × 10⁻⁶ 9 Ω

[0036] Volume resistivity: 7.1 × 10⁻⁶ 9 Ω

[0037] Average triboelectric potential: 168 V

[0038] Application results: The filter bag was used in the dust collector of a raw material mill in a cement plant. After 18 months of operation, the dust removal pressure was stable, and there were no cases of bag clogging or poor dust removal caused by static electricity. The anti-static performance remained stable after offline testing.

[0039] Example 2: A mixed conductive dust collector filter bag and its preparation method.

[0040] The filter bags are made of the following raw materials: high-strength, low-elongation polyester staple fibers of 2.0 dtex × 51 mm, and 310S stainless steel conductive staple fibers with a diameter of 8 μm and a length of 51 mm. The conductive fibers account for 2.5% of the total fiber mass. The base fabric is 100 g / m². 2Polyester filament woven fabric.

[0041] The filter bags are manufactured using the following process:

[0042] Add the two types of fibers into the opening mixer according to the above ratio, and mix thoroughly until the conductive fiber monofilaments are evenly dispersed.

[0043] After being carded by a carding machine, the fibers are cross-laid to form a uniform fiber web;

[0044] The fiber web is layered with the base fabric and pre-punched, with a punching density of 100 needles / cm. 2 Then perform the main puncture, with a needle density of 280 needles / cm². 2 The total needle density is 380 needles / cm². 2 The depth of the needle and the needle shape are matched to ensure that the fibers are fully entangled without being over-compacted;

[0045] First, heat setting is performed at 205℃, followed by calendering at 210℃ and 8MPa pressure to form a dense and smooth layer on the surface of the filter material, thereby improving dust removal properties.

[0046] Using antistatic sewing thread embedded with carbon fiber, the treated needle-punched felt was sewn into filter bags with a diameter of Φ160×6000mm. A megohmmeter was used to measure the resistance between the metal ring at the bag opening and the center of the bag bottom; the measured value was 8.2×10⁻⁶. The resistance from the bag opening to the middle of the bag body was also measured to be 8.2×10⁻⁶. 8 Ω.

[0047] Performance testing: Samples of the manufactured needle-punched felt were tested, and the results are as follows:

[0048] Weight: 580 g / m 2

[0049] Thickness: 1.95mm

[0050] Fracture strength: 1350 N (5*20cm) in the warp direction, 1520 N (5*20cm) in the weft direction.

[0051] Breathability: 15.2 m 3 / (m 2 ·min)

[0052] Surface resistivity: 2.9 × 10⁻⁶ 9 Ω

[0053] Volume resistivity: 5.5 × 10⁻⁶ 9 Ω

[0054] Application results: This filter bag is used in the carbon black industry to collect ultrafine dust. The calendered surface effectively prevents dust embedding, and the dust removal effect is excellent. The high strength ensures a long service life under high-pressure pulse cleaning.

[0055] Example 3: A mixed conductive dust collector filter bag and its preparation method.

[0056] The filter bags are made of the following raw materials: hydrolysis-resistant polyester staple fibers and nickel-based alloy conductive staple fibers with a diameter of 6μm. The conductive fibers account for 3.0% of the total fiber mass, and the base fabric is 100g / m². 2 Polyester filament woven fabric.

[0057] The filter bags are manufactured using the following process:

[0058] Add the two types of fibers into the opening mixer according to the above ratio, and mix thoroughly until the conductive fiber monofilaments are evenly dispersed.

[0059] After being carded by a carding machine, the fibers are cross-laid to form a uniform fiber web;

[0060] The fiber web is layered with the base fabric and pre-punched, with a punching density of 120 needles / cm. 2 Then perform the main puncture, with a needle density of 300 needles / cm². 2 The total needle density is 420 needles / cm². 2 The depth of the needle and the needle shape are matched to ensure that the fibers are fully entangled without being over-compacted;

[0061] First, heat setting is carried out, using impregnation, drying and sintering processes. A Teflon emulsion coating is applied to the surface of the filter material. After coating, the filter material exhibits excellent water and oil repellency. The hot rolling temperature is 210℃ and the pressure is 8MPa, which forms a dense and smooth layer on the surface of the filter material and improves dust removal.

[0062] Using antistatic sewing thread embedded with carbon fiber, the treated needle-punched felt was sewn into filter bags with a diameter of Φ160×6000mm. A megohmmeter was used to measure the resistance between the metal ring at the bag opening and the center of the bag bottom; the measured value was 4.1×10⁻⁶. The resistance from the bag opening to the middle of the bag body was also measured to be 4.1×10⁻⁶. 9 Ω.

[0063] Performance testing: Samples of the manufactured needle-punched felt were tested, and the results are as follows:

[0064] Weight: 560 g / m 2

[0065] Breathability: 14.0 m 3 / (m 2 ·min)

[0066] Application results: This filter bag is used in the carbon black industry to collect ultrafine dust. The calendered surface effectively prevents dust embedding, and the dust removal effect is excellent. The high strength ensures a long service life under high-pressure pulse cleaning.

[0067] Comparison Dimensions Example 1 Example 2 Example 3 polyester fiber 1.5dtex×38mm standard short fiber 2.0dtex×51mm high-strength, low-elongation short fiber Hydrolysis-resistant polyester staple fiber Conductive fiber (type / diameter) 316L stainless steel, 7μm 310S stainless steel, 8μm Nickel-based alloy, 6μm percentage of conductive fibers 1.5% 2.5% 3.0% base fabric 75g / m² polyester filament woven fabric 100g / m² polyester filament woven fabric 100g / m² polyester filament woven fabric Total acupuncture density 400 thorns / cm² 380 thorns / cm² 420 thorns / cm² Key finishing processes Singeing Calendering (210℃, 8MPa) Teflon (PTFE) coating

[0068] Example 2 uses coarse denier high-strength fibers to improve the overall strength of the filter bag and adapt to high-pressure pulse cleaning. Example 3 uses special fibers to cope with corrosive conditions. Example 3 uses an acid-resistant nickel-based alloy, demonstrating the material's adaptability to extreme conditions. The diameter is controlled within the critical range of 6-8 μm to ensure uniform blending and three-dimensional network formation. The slightly higher proportion of conductive fibers in Examples 2 and 3 corresponds to the requirements for higher strength / conductivity and performance stability under corrosive environments, respectively. Example 1 uses a lighter base fabric, focusing on air permeability and cost; Examples 2 and 3 use a heavier base fabric to provide stronger skeletal support and adapt to more demanding physical or chemical environments. Regarding the total needle-punching density, Example 1 uses a moderate density to balance strength and air permeability; Example 2 has a slightly lower density to allow for air permeability in the subsequent calendering and densification process; Example 3 has the highest density to compensate for the partial blockage of pores by the Teflon coating, ensuring that the final air permeability meets the standard. In Example 1, singeing is used to obtain a smooth surface, which is beneficial for dust removal. In Example 2, a calendering process is used to form a dense surface layer, which improves filtration accuracy and dust removal properties. In Example 3, a Teflon coating is used to give the filter material excellent water and oil repellency and chemical corrosion resistance. All three are based on heat setting and are designed to enhance functionality for different working conditions.

[0069] Comparative Example 1:

[0070] Ordinary polyester needle-punched felt of the same weight and specifications as in Example 1 was used, and in the final process it was impregnated with a commercially available silicone antistatic agent and then dried.

[0071] Performance: Initial surface resistivity is 10 8 The surface resistivity is in the Ω range, with a triboelectric potential of <200V. However, under simulated conditions (80℃, 60% relative humidity, and 50 hours of mechanical vibration and friction), the surface resistivity increases to >10Ω. 12 When the static electricity potential exceeds 2000V, the antistatic properties are essentially lost.

[0072] The antistatic agent method in Comparative Example 1 is not durable, while the present invention achieves permanent functionality through fiber-grade blended conductive fibers.

[0073] Comparative Example 2:

[0074] The needle-punched felt with the same weight and fiber as in Example 2 was used, but the base fabric was changed to a mesh conductive base fabric woven with stainless steel conductive yarns with a spacing of 10 mm, and the fiber web was pure polyester.

[0075] Performance testing:

[0076] Resistance non-uniformity: Measured directly above the conductive yarn, the surface resistance is 10. 5 Ω; Surface resistivity >10 Ω measured in the center region of the grid. 12 Ω.

[0077] Triboelectric potential: Friction in the center area of ​​the grid generates a static potential as high as 2850V, posing a serious risk of static electricity accumulation.

[0078] Strength: Due to the coarse and stiff conductive yarn embedded in the base fabric, its weft breaking strength is about 15% lower than that of Example 2.

[0079] The grid-based conductive method in Comparative Example 2 suffers from uneven protection and blind spots, which may also affect physical performance. In contrast, this invention achieves omnidirectional, blind-spot-free uniform electrostatic dissipation through a three-dimensional uniform conductive network.

[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A mixed conductive dust collector filter bag, characterized in that, The filter bag is made of needle-punched felt with mixed conductive fibers. The needle-punched felt contains uniformly blended polyester fibers and conductive fibers, and the conductive fibers form a three-dimensional network of continuous conductive pathways in the needle-punched felt. The weight of the needle-punched felt is 500-600 g / m², the thickness is 1.8-2.0 mm, and the surface resistivity is ≤5.0 × 10⁻⁶. 9 Ω, volume resistivity ≤9.9×10 9 Ω.

2. The conductive dust collector filter bag according to claim 1, characterized in that, The conductive fiber is made of stainless steel or corrosion-resistant alloy metal fiber, and the diameter of the conductive fiber is 6-8 micrometers.

3. The conductive dust collector filter bag according to claim 1, characterized in that, The conductive fiber accounts for 0.5%-5% of the total mass of all fibers in the mixed conductive fiber needle-punched felt, and all fibers are the sum of polyester fibers and conductive fibers.

4. The conductive dust collector filter bag according to claim 1, characterized in that, The breaking strength of the hybrid conductive fiber needle-punched felt meets the following requirements: warp ≥ 1100N (5*20cm), weft ≥ 1300N (5*20cm).

5. The conductive dust collector filter bag according to claim 1, characterized in that, The air permeability of the hybrid conductive fiber needle-punched felt is 13-16 m³ / (m²·min), the average value of the triboelectric potential is ≤185V, and the surface charge density is ≤2.37×10⁻ 8 C / m².

6. The conductive dust collector filter bag according to claim 1, characterized in that, The continuous operating temperature of the hybrid conductive fiber needle-punched felt is 120℃, and the instantaneous withstand temperature is 150℃.

7. A method for preparing a mixed-conductivity dust collector filter bag as described in claim 1, characterized in that, Includes the following steps: S1: Open and mix polyester fibers and conductive fibers in a certain proportion; S2: The mixed fibers are combed and laid into a web to form a fiber web; S3: The fiber web is stacked with the filament base fabric and needle-punched to make the fibers and base fabric entangled to form a needle-punched felt fabric with a three-dimensional conductive network. S4: Post-finishing of needle-punched felt fabric; S5: The finished needle-punched felt is sewn into a dust removal filter bag.

8. The method for preparing a mixed-conductive dust collector filter bag according to claim 7, characterized in that, In step S3, the acupuncture is performed in two steps: pre-needle and main needle, and the total needle density is 350-450 needles / square centimeter.

9. The method for preparing a mixed-conductive dust collector filter bag according to claim 7, characterized in that, The finishing process in step S4 includes at least heat setting, and also includes one or more of singeing, calendering and Teflon coating treatment.

10. The method for preparing a mixed-conductivity dust collector filter bag according to claim 7, characterized in that, In step S5, antistatic sewing thread is used for sewing, and after sewing is completed, the resistance between any two points on the filter bag is measured to check and ensure the overall conductivity continuity of the filter bag.