Surface fibrillated aramid fiber non-woven fabric treatment system

Abstract

The utility model discloses a surface fibrillated aramid fiber non-woven fabric treatment system, which is based on a composite process of chemical acid treatment splitting and mechanical spunlace splitting, can effectively improve the fibrillation degree and the filtering efficiency of a needled aramid fiber non-woven filter material, and simultaneously reduces the loss of treated fibers and the influence on the physical properties of the filter material. The treatment process is simple, and the treatment liquid can be recycled for multiple times. The treatment system comprises a needling device, a pretreatment pool, a first spraying device, an acid treatment pool, a second spraying device, a spunlace device and a drying device which are sequentially arranged in the direction of an assembly line. The needling device is used for preparing aramid fibers fed into the needling device into aramid non-woven fabric; pretreatment liquid is contained in the pretreatment pool and is used for cleaning the aramid fiber non-woven fabric; a chemical splitting reagent is contained in the acid treatment tank and is used for dipping the aramid fiber non-woven fabric; the spunlace device is used for performing spunlace processing on the aramid fiber non-woven fabric.

Description

Technical Field

[0001] The utility model relates to the technical field of non-woven fabric preparation, in particular to a surface fibrillation aramid non-woven fabric treatment system. Background Art

[0002] At present, the high-temperature resistant filter materials commonly used for flue gas dust removal filters at home and abroad are traditional needle-punched filters. However, due to factors such as the needle structure and needle-punching processing technology of this filter material, it has defects such as a larger pore size, low filtration accuracy, and low physical strength, and cannot better meet the requirements of PM2.5 emission standards. In order to solve the problem of low filtration efficiency of fiber non-woven fabrics, a film-coated needle-punched filter material has been developed in the industry. However, during the use of the film-coated needle-punched filter material, the film is easily damaged, and it cannot meet the actual application requirements in an environment with severe oil or dust abrasion, and cannot fundamentally solve the problem. In addition, the industry has also developed nanofibers with diameters ranging from dozens of nanometers to hundreds of nanometers as important raw materials for high-efficiency non-woven fabrics, and the filtration efficiency is improved by reducing the pore size. However, due to the inherent conflict between high filtration efficiency and low pressure drop, the actual application of nanofiber non-woven fabrics in air filtration is still largely limited to the laboratory. Therefore, researching more advanced technologies and developing products with better performance are important issues currently faced by scientific research personnel in the filter material industry.

[0003] To further improve the filtration characteristics of filter materials, it is necessary to further refine the fibers, that is, fibrillate (open the fibers). If the filter material fibers can reach a certain degree of splitting, the specific surface area of the fiber web can be further increased, thereby improving the filtration efficiency. The existing fibrillating and opening methods mainly include heat treatment methods, mechanical processing methods, and chemical methods. The advantages and disadvantages of each method are as follows:

[0004] (1) The heat treatment method implements fiber splitting based on the different thermal expansion properties of different high-polymer components at a certain temperature, and is mainly used for double-component and multi-component fiber filter materials; however, under the action of high temperature, the fibers of the heat-treated non-woven fabric are prone to adhesion and shrinkage, affecting the physical properties of the non-woven fabric and also reducing the fiber separation efficiency.

[0005] (2) The mechanical processing method mainly uses the method of hydroentangling treatment. Under the impact of a high-pressure water jet, some of the fibers on the filter material will separate into profiled filaments on the original relatively smooth cylindrical cross-section; however, generally, the pressure configuration of the hydroentangling head should be higher than 35 MPa. After the filter material is treated by high-pressure hydroentangling, the proportion of damaged fibers is higher than that of separated fibers. Therefore, the processing technology needs to be further improved.

[0006] (3) The chemical method uses the alkali weight reduction method, acid treatment method or swelling agent treatment method to fibrillate non-woven fabrics. In the reaction system, the reagents can act on the materials evenly, so it has good development prospects. Among them, fiber loss will occur after alkali treatment, resulting in loose filter materials, decreased strength and reduced durability; in the swelling agent treatment method, since the fibers are separated by swelling, relatively more solvents will enter the amorphous region of the fibers, which will have a certain impact on the physical properties of the fibers (such as tensile strength, bending properties, etc.); the acid treatment method has only achieved phased results in the laboratory at present. After treatment with strong acid, although the fiber has a large fibrillation rate, there are also problems such as large fiber degradation loss and has not been industrialized yet. Summary of the Invention

[0007] The purpose of the present invention is to provide a surface fibrillated aramid non-woven fabric treatment system. Based on the composite process of chemical acid treatment fibrillation and mechanical hydroentangling fibrillation, it can effectively improve the fibrillation degree and filtration efficiency of needle-punched aramid non-woven filter materials, while reducing the loss of treated fibers and the impact on the physical properties of the filter materials, and the treatment process is simple, and the treatment liquid can be recycled multiple times.

[0008] In order to achieve the above purpose, the solution of the present invention is:

[0009] A surface fibrillated aramid non-woven fabric treatment system includes a needle punching device, a pretreatment tank, a first spraying device, an acid treatment tank, a second spraying device, a hydroentangling device and a drying device arranged in sequence along the pipeline direction; the needle punching device is used to prepare aramid non-woven fabric from the fed aramid fibers; the pretreatment tank is filled with a pretreatment liquid to clean the aramid non-woven fabric; the first spraying device is used to wash the residual pretreatment liquid in the aramid non-woven fabric; the acid treatment tank is filled with a chemical fibrillation reagent to impregnate the aramid non-woven fabric; the second spraying device is used to wash the residual chemical fibrillation reagent in the aramid non-woven fabric; the hydroentangling device performs hydroentangling processing on the aramid non-woven fabric; the drying device is used to dry the aramid non-woven fabric passing through the hydroentangling device.

[0010] The pretreatment liquid contained in the pretreatment tank is a mixed solution of acetone and ethanol.

[0011] Preferably, in the pretreatment liquid, the mixing ratio of acetone to ethanol is 1:1.

[0012] The chemical fibrillation reagent contained in the acid treatment tank is a phosphoric acid solution of 2-5 mol / L, a sulfuric acid solution of 1-2 mol / L or a hydrochloric acid solution of 0.5-2 mol / L.

[0013] The drying device is a dryer.

[0014] After adopting the above technical solution, the utility model has the following technical effects:

[0015] By using a chemical fibrillation reagent to treat conventional aramid nonwoven fabrics, the utility model can successfully activate the surface fibrillation of microfibers on the surface of the filter material, generate a large number of short nanofibers on the fiber surface, and make the short nanofibers split and form longer nanofibers by means of the repeated impact and rebound scattering of the high-pressure water flow of the hydroentangling process; compared with a single chemical fibrillation or mechanical fibrillation process, the utility model provides a composite process based on chemical acid treatment fibrillation and mechanical hydroentangling fibrillation. The fibers in the fibrillation aramid nonwoven fabric prepared by it are less damaged and more tightly entangled with each other. Therefore, the target product can have a higher tensile breaking strength to better meet the requirements of actual working conditions; in addition, the structure and process flow of the utility model are relatively simple, the raw material cost is low, and the chemical fibrillation reagent can also be reused, which is suitable for mass production. Brief Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of the treatment system of the utility model;

[0017] Figure 2 It is an SEM image of the aramid nonwoven fabric prepared by needling in Example 1 of the utility model;

[0018] Figure 3 It is an SEM image of the aramid nonwoven fabric in Example 1 of the utility model after acid treatment;

[0019] Figure 4 It is an SEM image of the aramid nonwoven fabric in Example 1 of the utility model after hydroentangling treatment.

[0020] Explanation of the reference numerals in the drawings:

[0021] 1 - Needling device; 2 - Pretreatment tank; 3 - First spraying device; 4 - Acid treatment tank; 5 - Second spraying device; 6 - Hydroentangling device; 7 - Drying device. Detailed Description of the Embodiments

[0022] In order to further explain the technical solution of the utility model, the utility model will be elaborated in detail below through specific embodiments.

[0023] The utility model discloses a surface fibrillation aramid nonwoven fabric treatment system, which includes a needling device 1, a pretreatment tank 2, a first spraying device 3, an acid treatment tank 4, a second spraying device 5, a hydroentangling device 6 and a drying device 7 arranged in sequence along the pipeline direction;

[0024] The needling device 1 is used to prepare aramid nonwoven fabric from the aramid fibers fed into it;

[0025] The pretreatment tank 2 is filled with a pretreatment liquid for cleaning the aramid nonwoven fabric;

[0026] The first spraying device 3 is used to wash the residual pretreatment liquid in the aramid nonwoven fabric;

[0027] The acid treatment tank 4 is filled with a chemical fiber opening reagent for impregnating the aramid nonwoven fabric;

[0028] The second spraying device 5 is used to wash the residual chemical fiber opening reagent in the aramid nonwoven fabric;

[0029] The hydroentangling device 6 performs hydroentangling processing on the aramid nonwoven fabric;

[0030] The drying device 7 is used to dry the aramid nonwoven fabric that has passed through the hydroentangling device 6.

[0031] The pretreatment liquid contained in the above-mentioned pretreatment tank 2 can be a mixed solution of acetone and ethanol; preferably, the mixing ratio of acetone to ethanol is 1:1.

[0032] The chemical fiber opening reagent contained in the above-mentioned acid treatment tank 4 is a 2-5 mol / L phosphoric acid solution, a 1-2 mol / L sulfuric acid solution, or a 0.5-2 mol / L hydrochloric acid solution. Using a strong acid with a lower concentration for acid treatment can generate a large number of short nanofibers on the fiber surface. On the one hand, it reduces the influence of strong acid corrosion on the fiber loss rate. On the other hand, in the subsequent hydroentangling process that can form longer nanofibers, the hydroentangling pressure of the hydroentangling device 6 can be reduced, further reducing the damage to the fibers caused by the high water pressure of hydroentangling.

[0033] The above-mentioned drying device 7 is a dryer.

[0034] The present utility model also discloses a method for treating a surface fibrillated aramid nonwoven fabric, applying the above-mentioned treatment system, which includes the following steps:

[0035] Step 1: Needle punching preparation of the aramid nonwoven fabric: The aramid fibers that are evenly laid out after opening and carding are fed into the needle punching device 1 through a conveying device such as a drafting machine for pre-needle punching processing to prepare the aramid nonwoven fabric.

[0036] Step 2: Pretreatment of the aramid nonwoven fabric: Immerse the aramid nonwoven fabric in the pretreatment liquid in the pretreatment tank 2 for cleaning to remove the oil stains and impurities adhered to the surface; then send it into the first spraying device 3 for washing to remove the residual pretreatment liquid.

[0037] Step 3: Acid treatment of the aramid nonwoven fabric: Immerse the pretreated aramid nonwoven fabric in the chemical fiber opening reagent in the acid treatment tank 4 and perform constant temperature treatment under preset temperature and time conditions; then send it into the second spraying device 5 for washing to remove the residual chemical fiber opening reagent.

[0038] Step 4, hydroentangling treatment of aramid nonwoven fabric: Feed the acid-treated aramid nonwoven fabric into the hydroentangling device 6 for hydroentangling processing. Continuously spray the aramid nonwoven fabric with water flow. Under the action of the water flow spraying, the fibrillation phenomenon of aramid fibers can be further enhanced.

[0039] Step 5, drying of aramid nonwoven fabric: Feed the hydroentangled aramid nonwoven fabric into the drying device 7 and dry it under preset temperature conditions.

[0040] In the above step 3, set the treatment temperature of the acid treatment tank 4 to 20 - 70 °C and the treatment time to 1 - 8 h.

[0041] In the above step 4, set the hydroentangling pressure of the hydroentangling device 6 to 25 - 30 MPa.

[0042] In the above step 5, set the drying temperature of the drying device 7 to 120 °C.

[0043] Through the above solution, the utility model can successfully activate the surface fibrillation of microfibers on the surface of the filter material by using chemical fibrillation reagents to treat conventional aramid nonwoven fabrics, and a large number of short nanofibers are generated on the fiber surface. With the repeated impact and rebound scattering of the high-pressure water flow in the hydroentangling process, the short nanofibers are split to form longer nanofibers. Compared with the single chemical fibrillation or mechanical fibrillation process, the utility model provides a composite process based on chemical acid treatment fibrillation and mechanical hydroentangling fibrillation. The fibers in the fibrillated aramid nonwoven fabric prepared by it have less damage and are more tightly entangled with each other. Therefore, the target product can have a higher tensile breaking strength to better meet the actual working conditions requirements. In addition, the structure and process flow of the utility model are relatively simple, the raw material cost is low, and the chemical fibrillation reagents can also be reused, which is suitable for mass production.

[0044] The following shows Embodiment 1 of the utility model.

[0045] Step 1, needle punching preparation of aramid nonwoven fabric: Feed the opened and carded aramid fibers evenly laid through a conveying device such as a drafting machine into the needle punching device 1 for pre-needle punching processing to prepare aramid nonwoven fabric.

[0046] Step 2, pretreatment of aramid nonwoven fabric: Immerse the aramid nonwoven fabric in the pretreatment tank 2, clean it in the pretreatment liquid of acetone and ethanol with a ratio of 1:1, and then feed it into the first spraying device 3 for cleaning to remove the residual pretreatment liquid.

[0047] Step 3. Acid treatment of the aramid nonwoven fabric: Immerse the pretreated aramid nonwoven fabric in the acid treatment tank 4, impregnate it in a 4 mol / L phosphoric acid solution, set the temperature at 70 °C, and impregnate for 2 h; then send it to the second spraying device 5 for cleaning to remove the residual phosphoric acid solution.

[0048] Step 4. Hydroentangling treatment of the aramid nonwoven fabric: Send the acid-treated aramid nonwoven fabric to a hydroentangling device 6 with a hydroentangling pressure of 27 MPa for hydroentangling processing.

[0049] Step 5. Drying of the aramid nonwoven fabric: Send the hydroentangled aramid nonwoven fabric to a drying device 7 for drying at 120 °C.

[0050] The data obtained through testing in the above Example 1 are as follows:

[0051]

[0052] As can be seen from the above table, after being treated by the method of the present invention, the dust removal efficiency of the aramid nonwoven fabric in Example 1 is greatly improved, and the tensile breaking strength remains basically unchanged.

[0053] In addition, for the SEM images of the aramid nonwoven fabric before and after treatment in Example 1, see Figures 2 to 4 , and it can be seen that a large number of nanofibers have been peeled off from the fiber surface.

[0054] The following shows Example 2 of the present utility model.

[0055] Step 1. Needle-punching preparation of the aramid nonwoven fabric: Feed the aramid fibers evenly spread after opening and carding into a needle-punching device 1 through a conveying device such as a drafting machine for pre-needle-punching processing to prepare the aramid nonwoven fabric.

[0056] Step 2. Pretreatment of the aramid nonwoven fabric: Immerse the aramid nonwoven fabric in the pretreatment tank 2, clean it in a pretreatment solution of acetone and ethanol at a ratio of 1:1, and then send it to the first spraying device 3 for cleaning to remove the residual pretreatment solution.

[0057] Step 3. Acid treatment of the aramid nonwoven fabric: Immerse the pretreated aramid nonwoven fabric in the acid treatment tank 4, impregnate it in a 1 mol / L hydrochloric acid solution, set the temperature at 25 °C (i.e., room temperature), and impregnate for 4 h; then send it to the second spraying device 5 for cleaning to remove the residual hydrochloric acid solution.

[0058] Step 4. Hydroentangling treatment of the aramid nonwoven fabric: Send the acid-treated aramid nonwoven fabric to a hydroentangling device 6 with a hydroentangling pressure of 25 MPa for hydroentangling processing.

[0059] Step 5, drying of the aramid nonwoven fabric: Feed the hydroentangled aramid nonwoven fabric into the drying device 7 and dry it at 120 °C.

[0060] The data obtained from the above-mentioned Example 2 through testing are as follows:

[0061]

[0062] As can be seen from the above table, after being treated by the method of the present utility model, the dust removal efficiency of the aramid nonwoven fabric in Example 2 is also greatly improved, and compared with that before treatment, the tensile breaking strength of the aramid nonwoven fabric decreases less, and it has a high strength retention rate.

[0063] The above embodiments do not limit the product form and style of the present utility model. Any appropriate changes or modifications made by those of ordinary skill in the art shall be regarded as not departing from the patent scope of the present utility model.

Claims

1. A surface fibrillated aramid nonwoven fabric processing system, characterized in that: It includes a needle puncture device, a pretreatment tank, a first spray device, an acid treatment tank, a second spray device, a water puncture device and a drying device which are sequentially arranged along the production line direction; The needle punching device is used to prepare aramid fibers fed therein into aramid nonwoven fabrics; The pretreatment tank contains a pretreatment liquid to clean the aramid nonwoven fabric; The first spray device is used to clean the residual pretreatment liquid in the aramid nonwoven fabric; The acid treatment tank contains a chemical fiber opening agent for impregnating the aramid nonwoven fabric; The second spray device is used to clean the chemical fiber opening agent remaining in the aramid nonwoven fabric; The spunlace device performs spunlace processing on the aramid nonwoven fabric; The drying device is used for drying the aramid nonwoven fabric that has passed through the hydroentanglement device.

2. The surface fibrillated aramid nonwoven fabric processing system according to claim 1, characterized in that: The drying device is a drying machine.

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