A preparation process for needle-punched dust removal filter cloth

Abstract

The present invention relates to the technical field of product processing and forming, and discloses a preparation process method for a needle-punched dust removal filter cloth, comprising the following steps: step S1: weaving at a suitable temperature; step S2: calendering and singeing; step S3: shaping; step S4: protective treatment; step S5: impregnation treatment; step S6: coating treatment; step S7: air drying treatment; and step S8: sewing. The filter cloth made by the preparation process method for the needle-punched dust removal filter cloth can greatly reduce the stress in the fiber itself, so that the filter bag can be used in high and low temperature environments, reduce the environmental stress of thermal expansion and contraction, improve the stability of the filter cloth, and thus improve the overall filtering effect of the filter cloth. At the same time, the entire initial weaving state is woven in a suitable temperature environment, directly corresponding to the temperature of its application scenario, so the gap of the filter cloth will deform very little in its working environment, thereby avoiding the change of the cloth gap caused by thermal expansion and contraction, and further improving the filtering effect of the entire filter cloth.

Description

Technical Field

[0001] The invention relates to the technical field of product processing and forming, and in particular to a preparation process method of a needle-punched dust removal filter cloth. Background Art

[0002] At present, bag dust collectors are mostly used to filter dust-laden gases. The working principle is to introduce dust-laden gases into the bag dust collector box through connecting pipes. The dust-laden gases move toward the filter bags under the gravitational force of the induced draft fan. The dust is adsorbed on the filter bags, and the purified gases are discharged from the filter bags, thereby achieving the effect of air purification.

[0003] However, when dealing with the filtering process of some fine dust, such as in the production process of some flour enterprises or the processing process of some coal plants, the dust particles are very small in size, and the traditional filter cloth is a cloth fiber that easily generates static electricity, which causes dust and static electricity to become flammable and explosive. There is a certain degree of safety hazard, which greatly threatens the safety of operators. At the same time, the traditional cloth fiber filter bag will be affected by thermal expansion and contraction when passing through some low or high temperature environments, causing the filter gap of the bag to automatically change with the environment, thereby changing the working dust removal gap of the entire dust bag, reducing its stability, and thus greatly reducing the filtering effect of the filter cloth. In view of this, a preparation process method for needle-punched dust filter cloth is proposed. Summary of the Invention

[0004] Technical problems solved

[0005] In view of the deficiencies of the prior art, the present invention provides a preparation process for a needle-punched dust removal filter cloth, which solves the problems raised in the background art.

[0006] Technical Solution

[0007] To achieve the above object, the present invention provides the following technical solution: a preparation process of a needle-punched dust filter cloth comprises the following steps;

[0008] Step S1: Weaving at a suitable temperature, weaving the metal fiber and the polyester fiber at the working temperature of the actual use scenario of the filter cloth to obtain an initial cloth 1;

[0009] Step S2: calendering and singeing, performing calendering and singeing treatment on the initial fabric 1 to obtain the initial fabric 2;

[0010] Step S3: shaping, converting the initial fabric 2 from a low temperature to a high temperature environment for shaping, to obtain the initially formed fabric 1;

[0011] Step S4: Protective treatment, placing the first preformed fabric in a waterproofing agent and an oil-repellent agent for treatment to obtain the second preformed fabric;

[0012] Step S5: impregnation treatment, impregnating the primary formed fabric 2 in a PTFE solution above room temperature, then drying and storing at a low temperature to obtain the primary formed fabric 3;

[0013] Step S6: coating the surface of the primary formed fabric 3 with a layer of expanded PTFE film to obtain the primary formed fabric 4;

[0014] Step S7: air-drying treatment, placing the pre-formed fabric 4 in a high-low temperature circulation space for rotary air-drying to obtain a formed filter material;

[0015] Step S8: Suturing, sewing the formed filter material to obtain the final needle-punched dust removal filter cloth.

[0016] Preferably, the weaving in step S1 is performed using a fiber weaving machine, the model of which is a JLB-130 wire mesh weaving machine, and the weaving method used is satin weaving.

[0017] Preferably, the diameter of the metal fiber in step 1 is 1.5 μm, and the mass ratio of the metal fiber to the polyester fiber is 1:4.5, and the metal fiber is an organic conductive fiber.

[0018] Preferably, the actual usage scenarios in step S1 include low temperature, room temperature or high temperature environments, the low temperature environment is -40°C to 10°C, the room temperature environment is 10°C to 35°C, and the high temperature environment is 45°C to 75°C.

[0019] Preferably, the initial cloth is calendered and singed by the following steps:

[0020] Step A1: placing an initial roll of fabric on a drum;

[0021] Step A2: using a high-temperature roller 2 at 230° C. to contact and roll the initial fabric 1 on the roller 1;

[0022] Step A3: High-speed air suction is applied to the surface of the initial fabric 1 after rolling in step A2 to obtain initial fabric 2.

[0023] Preferably, the initial fabric 2 is shaped by the following steps:

[0024] Step B1: Place two rolls of initial fabric on several rollers with different temperatures, with the lowest roller temperature being -20°C and each roller temperature varying from 10°C to 50°C until the last roller temperature reaches 185°C.

[0025] Step B2: Cool the fabric in step B1 to room temperature.

[0026] Preferably, in step S4, the primary formed fabric 1 is placed in a waterproof agent at 50°C-90°C and soaked for 30min-50min, then air-dried and placed in an oil-repellent at 50°C-90°C for 30min-55min, and then air-dried again to obtain the primary formed fabric 2.

[0027] Preferably, the immersion time in step S5 is 1 hour at a temperature higher than room temperature, specifically 60° C.-80° C.; the storage time in step S5 is ≥6 hours at a low temperature environment of -20° C. to -5° C.

[0028] Preferably, the lowest temperature of the high and low temperature circulation space in step S7 is -20°C and the highest temperature is 150°C, and the temperature is changed every 20 minutes to air-dry the fabric.

[0029] Beneficial effects

[0030] Compared with the prior art, the present invention provides a method for preparing a needle-punched dust filter cloth, which has the following beneficial effects:

[0031] The filter cloth produced by the preparation process of this needle-punched dust filter cloth can greatly reduce the inherent stress in the fibers, thereby enabling the filter bag to be used in high and low temperature environments, reducing the environmental stress of thermal expansion and contraction, improving the stability of the filter cloth, and thus improving the overall filtering effect of the filter cloth. At the same time, the entire initial weaving state is woven in a suitable temperature environment, directly corresponding to the temperature of its application scenario, so the gap of the filter cloth will deform very little in its working environment, thereby avoiding the change of the cloth gap caused by thermal expansion and contraction, and further improving the filtering effect of the entire filter cloth. In the subsequent steps, the filter cloth is still processed using the hot and cold cycle method to minimize the deformation stress of the filter cloth and improve the stability of subsequent use. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] A method for preparing a needle-punched dust removal filter cloth comprises the following steps:

[0034] Step S1: suitable temperature weaving, metal fiber and polyester fiber are weaved at the working temperature of the actual use scene of filter cloth to obtain initial cloth one; fiber braiding machine is used to weave, because it is not considered to be weaved at room temperature, so it is necessary to use a woven method to weave, and its consistency of the woven method is relatively good, and the braiding machine model of the present embodiment is a JLB-130 type screen weaving machine, and the weaving method adopted is satin weaving, and the weaving method of satin weave filter cloth is that a weft (or warp) floats on several warps (or wefts), then sinks under a warp (or weft), and alternates in this way. The satin weave adopted has a smooth surface, is relatively too smooth, is convenient for subsequent vibration treatment of dust, and compared to traditional twill and plain weave, it has a thick texture and is soft, and has good drape, because filter cloth is basically in a draped state, wrinkles will not appear on its surface, and wind resistance will also be improved, and wind uniformity will also be better. The metal fiber has a diameter of 1.5 μm, and the mass ratio of metal fiber to polyester fiber is 1:4.5. The metal fiber is made of organic conductive fiber. Considering the generation of static electricity, which can easily cause explosions in small dust particles upon contact with static electricity, adding metal fiber to the filter cloth can effectively prevent static electricity and improve its safety during use. The entire initial weaving process is performed at a suitable temperature, directly corresponding to the application temperature. Therefore, the gaps in the filter cloth will deform minimally under the operating environment, thus preventing changes in the fabric gaps caused by thermal expansion and contraction, further improving the overall filtering effect of the filter cloth.

[0035] Step S2: calendering and singeing, performing calendering and singeing treatment on the initial fabric 1 to obtain the initial fabric 2;

[0036] The initial fabric is calendered and singed by the following steps:

[0037] Step A1: placing an initial roll of fabric on a drum;

[0038] Step A2: using a high-temperature roller 2 at 230° C. to contact and roll the initial fabric 1 on the roller 1;

[0039] Step A3: High-speed air suction is applied to the surface of the initial fabric 1 after rolling in step A2 to obtain initial fabric 2. This smoothes one side of the fabric and improves the dust removal performance of the filter media. However, conventional rolling methods can easily reduce the air permeability of the filter media. Therefore, after high-temperature rolling, this embodiment utilizes the remaining plasticity after rolling to cool the surface with a high-speed fan. This also moderately opens the gaps between each fiber, reducing the reduction in air permeability caused by high-temperature rolling.

[0040] Step S3: shaping, converting the initial fabric 2 from a low temperature to a high temperature environment for shaping, to obtain the initially formed fabric 1;

[0041] The initial fabric 2 is shaped by the following steps:

[0042] Step B1: Place two rolls of initial fabric on several rollers with different temperatures, with the lowest roller temperature being -20°C and each roller temperature varying from 10°C to 50°C until the last roller temperature reaches 185°C.

[0043] Step B2: Cool the fabric in step B1 to room temperature.

[0044] First, slowly transitioning from low temperature to high temperature can greatly reduce the inherent stress of the fabric and reduce deformation. The main function of shaping is to eliminate stress. In this embodiment, the stress is slowly transitioned from low temperature to high temperature to improve the applicability of the filter cloth. Because the stress of the fabric in each environment is different, the traditional method only pre-treats it in a high temperature environment, and the stress caused by the low temperature environment cannot be eliminated. Therefore, in the process of transitioning from low temperature to high temperature, the stress of the fabric at various temperatures can be greatly eliminated, thereby improving the final stability of the fabric.

[0045] Step S4: Protective treatment, placing the preformed fabric 1 in a waterproofing agent and an oil-repellent agent for treatment to obtain the preformed fabric 2; this step is mainly to improve the performance of the filter cloth in water-containing and oil-containing media, because considering that the usage scenario may be in water or in an environment with oil pollution, if the traditional filter cloth is not treated with waterproofing and oil-repellent, it is easy to cause the dust filtering performance of the filter cloth to decrease after long-term use. Therefore, after the waterproofing agent and oil-repellent agent are attached to the surface and inside of the entire fabric, some oil-water compounds cannot strongly adhere to the surface of the fabric or penetrate into the fabric.

[0046] Step S5: Impregnation treatment: The preformed fabric 2 is impregnated in a PTFE solution above room temperature, then dried and stored at low temperature to obtain preformed fabric 3. The impregnation time is 1 hour at a temperature above room temperature, specifically 70°C, and 8 hours at a low temperature, -10°C. The impregnation treatment also provides surface protection. Because the filter cloth is used in acidic and alkaline environments, acidic gases can significantly corrode the surface of traditional filter bags. Over time, if this part is severely corroded, its wind resistance during the ash filtering process is greatly reduced, and there is a risk of tearing. Therefore, after impregnation, the PTFE solution adheres to the surface of the fabric, which can improve its heat resistance and chemical corrosion resistance. Storing it at low temperature allows the PTFE solution to be effectively adhered and fixed to the fabric, reducing volatilization. At low temperature, the fabric can also be initially shaped. In high temperature environments, the solution has a certain volatility, resulting in uneven adhesion. Therefore, after impregnation, drying and storing it at low temperature can effectively preserve the PTFE solution adhered to the surface.

[0047] Step S6: Coating. The surface of the preformed fabric (3) is coated with an expanded PTFE membrane to produce preformed fabric (4). This membrane has a high porosity and small pore size, which improves dust removal efficiency and achieves near-zero emissions. Woven or non-woven filter media is coated with a thin layer of polytetrafluoroethylene film. The purpose of coating is to provide surface filtration, allowing only gas to pass through the filter media while retaining any dust contained within the gas on the fabric surface. Coated fabrics offer excellent performance, employing surface filtration, achieving near-100% retention of the filtered material. With coated filter cloth, dust cannot penetrate the filter media, resulting in surface filtration. Both coarse and fine dust are deposited on the filter media surface, effectively retaining the filtered material through the membrane's pore size. There is no initial filtration period, ensuring effective filtration from the start, 100% of the time. There are two types of lamination methods: adhesive lamination, a more basic method with low lamination strength, easy delamination, and a short lifespan. Adhesive penetration leads to poor air permeability, making cleaning difficult and weakening the superior properties of PTFE. Thermal lamination, on the other hand, fully maintains the superior properties of PTFE. This embodiment utilizes thermal lamination, using a high-temperature filter bag dust removal laminating machine to coat the fabric surface, achieving both easy cleaning and high permeability.

[0048] Step S7: Air-drying: The preformed fabric is placed in a high- and low-temperature circulation chamber for rotary air-drying to obtain the finished filter material. Also considering the applicable space, the high- and low-temperature circulation chamber is set up, starting with a minimum temperature of -20°C and gradually transitioning to a high temperature of 150°C. After drying for 20 minutes at each temperature, the filter material gradually adapts to the temperature before being air-dried again at a different temperature. This greatly reduces deformation and stress on the filter cloth, ensuring that the finished filter material, once sewn into filter bags, can adapt to different usage scenarios.

[0049] Step S8: Suturing, sewing the formed filter material to obtain the final needle-punched dust removal filter cloth.

[0050] The requirements for suturing are relatively high, and it is divided into five steps in total.

[0051] Step C1: Fabricate the elastic ring. The specifications of the elastic ring are crucial for successful installation. Its diameter is determined by the length of the blank. The center-to-center distance of the elastic ring should be within ±0.5 mm. The width of the elastic ring is generally between 19 and 30 mm. The rivets at the elastic ring joints should be straight, flat, and smooth.

[0052] Step C2: Production and sewing of concave groove strips. The concave groove strips are sewn with a professional sewing machine. The groove width of the concave groove strips and the thickness of the selected fabric are key factors. The groove width of the concave groove strips should be uniform. When bonding the concave groove strips to the elastic ring, the center of the groove should correspond to the center of the elastic ring width, and the grooves at the joints should be aligned to avoid installation difficulties.

[0053] Step C3: Production and sewing of the bag opening. The blanking material of the bag opening is generally a parallelogram. It is first sewn into a cylindrical shape. When installing the elastic ring and the concave groove assembly, pay attention to the neatness of the edges to ensure that the groove width does not narrow when the concave groove strip is installed. At the same time, a week of stitches are sewn along the circumference as close to the edge of the elastic ring and the concave groove assembly as possible. No skew is allowed when sewing the bag opening and the bag body. Generally, the spacing between the stitches for three weeks should be uniform and beautiful. The material of the sewing thread used must be the same as or higher than the material of the filter bag. In special working conditions, there should be at least one week of high-temperature resistant and corrosion-resistant stitches. All stitches should be firm and reliable, without skipping or floating threads. The stitch length is between 3.3 and 4.2 mm.

[0054] Step C4: Fabricate and sew the bag bottom. The bag bottom is typically sewn with a reinforcement layer, typically 60 to 100 mm high. (Use professional cutting equipment to cut.) First, sew the reinforcement layer into a cylindrical shape, then sew it to the outside of the bottom, staggering the seam stitching with the seam stitching of the filter bag body. Use a single or double needle to sew the reinforcement layer around the circumference for 1 to 2 times. When sewing the bag bottom, if using a single needle stitch, keep the stitch spacing 4 to 5 mm, and the outermost stitching should be 4 to 5 mm away from the edge.

[0055] Step C5: Sewing the bag body. The bag body is sewn using a three-needle six-thread machine. The stitches should be straight without floating threads, skipped threads, or dropped threads. The stitch length should be between 3.3 and 4.2 mm. The outermost stitches should be 2 to 3 mm away from the edge. When sewing longer filter bags, the stitches are prone to twisting. During the sewing process, ensure that the upper and lower pieces are sewn synchronously to avoid twisting of the filter bag sewing stitches.

[0056] In summary, the filter cloth produced by this needle-punched dust filter cloth preparation process can significantly reduce the inherent stress in the fibers, allowing the filter bag to be used in high and low temperature environments and to be more stable when used at the optimal weaving temperature. This reduces the environmental stress of thermal expansion and contraction, improves the stability of the filter cloth, and thus enhances the overall filtering effect of the filter cloth. Furthermore, the entire initial weaving process is performed at an optimal temperature, directly corresponding to the application temperature. When weaving at room temperature, if the working environment is low or high temperature, it will experience a certain degree of thermal expansion and contraction, causing the gaps in the filter cloth to change, becoming uncontrollable. The filter cloth will shrink in actual high-temperature environments. This shrinkage is due to the fiber particle size increasing at high temperatures. When all particle sizes increase, an overall shrinkage effect occurs. Under the influence of low temperatures, the fiber particle size shrinks, resulting in a slight increase in the overall filter cloth gap. This affects the filter cloth's ash filtering performance. Therefore, the initial weaving is carried out at different temperatures, and the subsequent processing method will mostly be to use a low temperature to high temperature method to avoid the change of fabric gaps caused by thermal expansion and contraction, and further improve the filtering effect of the overall filter cloth.

[0057] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a needle-punched dust filter cloth, characterized in that: The following steps are included Step S1: Weaving at a suitable temperature, weaving the metal fiber and the polyester fiber at the working temperature of the actual use scenario of the filter cloth to obtain an initial cloth 1; Step S2: calendering and singeing, performing calendering and singeing treatment on the initial fabric 1 to obtain the initial fabric 2; Step S3: shaping, converting the initial fabric 2 from a low temperature to a high temperature environment for shaping, to obtain the initially formed fabric 1; Step S4: Protective treatment, placing the first preformed fabric in a waterproofing agent and an oil-repellent agent for treatment to obtain the second preformed fabric; Step S5: impregnation treatment, impregnating the primary formed fabric 2 in a PTFE solution above room temperature, then drying and storing at a low temperature to obtain the primary formed fabric 3; Step S6: coating the surface of the primary formed fabric 3 with a layer of expanded PTFE film to obtain the primary formed fabric 4; Step S7: air-drying treatment, placing the pre-formed fabric 4 in a high-low temperature circulation space for rotary air-drying to obtain a formed filter material; Step S8: Suturing, sewing the formed filter material to obtain the final needle-punched dust removal filter cloth.

2. The method for preparing the needle-punched dust filter cloth according to claim 1, characterized in that: The weaving in step S1 is performed using a fiber weaving machine, the model of which is a JLB-130 wire mesh weaving machine, and the weaving method used is satin weaving.

3. The method for preparing the needle-punched dust filter cloth according to claim 1, characterized in that: The diameter of the metal fiber in step S1 is 1.5 μm, and the mass ratio of the metal fiber to the polyester fiber is 1:4.

5. The metal fiber is an organic conductive fiber.

4. The method for preparing a needle-punched dust filter cloth according to claim 1, wherein: The actual usage scenarios in step S1 include low temperature, room temperature or high temperature environments, wherein the low temperature environment is between -40°C and 10°C, the room temperature environment is between 10°C and 35°C, and the high temperature environment is between 45°C and 75°C.

5. The method for preparing the needle-punched dust filter cloth according to claim 1, characterized in that: The initial fabric is calendered and singed by the following steps: Step A1: placing an initial roll of fabric on a drum; Step A2: using a high-temperature roller 2 at 230° C. to contact and roll the initial fabric 1 on the roller 1; Step A3: High-speed air suction is applied to the surface of the initial fabric 1 after rolling in step A2 to obtain initial fabric 2.

6. The method for preparing a needle-punched dust filter cloth according to claim 1, wherein: The initial fabric 2 is shaped by the following steps: Step B1: Place two rolls of initial fabric on several rollers at different temperatures, with the lowest roller temperature being -20°C and each roller temperature varying from 10°C to 50°C until the last roller temperature reaches 185°C. Step B2: Cool the fabric in step B1 to room temperature.

7. The method for preparing a needle-punched dust filter cloth according to claim 1, characterized in that: In step S4, the first preformed fabric is placed in a waterproof agent at 50°C-90°C and soaked for 30-50 minutes, then air-dried and placed in an oil-repellent at 50°C-90°C for 30-55 minutes, and then air-dried again to obtain the second preformed fabric.

8. The method for preparing a needle-punched dust filter cloth according to claim 1, wherein: The temperature higher than room temperature in step S5 is specifically 60° C.-80° C., the soaking time is 1 hour, the low temperature environment in step S5 is -20° C. to -5° C., and the storage time is ≥6 hours.

9. The method for preparing a needle-punched dust filter cloth according to claim 1, characterized in that: The lowest temperature of the high and low temperature circulation space in step S7 is -20°C and the highest temperature is 150°C, and the temperature is changed every 20 minutes to air-dry the fabric.