Composite filter cloth of plate-and-frame filter for filtering spinning solution

Abstract

The utility model relates to the technical field of filter cloth, in particular to composite filter cloth of a plate-and-frame filter for filtering spinning solution, which comprises a filter layer, an interception layer and a corrosion-resistant layer which are sequentially arranged, the filter material of the filter layer is cotton cloth, the filter material of the interception layer is non-woven fabric, and the filter material of the corrosion-resistant layer is PET (polyethylene terephthalate) fiber cloth. Through the composite design, the dirt holding rate of the filter cloth is improved, the impurity intercepting effect and the filtering efficiency of the filter cloth are improved, the service life of the filter cloth is prolonged, the filter cloth has remarkable advantages in application in acrylic fiber and carbon fiber precursor production processes, the problems that traditional filter cloth is aged, damaged and adhered to a plate and the like can be solved, the aged and decomposed filter cloth is prevented from forming impurities to pollute a spinning solution, and the product quality is improved. The filtering quality of the stock solution is ensured, the replacement frequency of the filter cloth is reduced, the overall production efficiency is improved, the production cost is reduced, and higher economic benefits are brought.

Description

Technical Field

[0001] This utility model belongs to the field of filter cloth technology, specifically, it relates to a composite filter cloth for a plate and frame filter press for filtering spinning solution. Background Technology

[0002] In the production process of carbon fiber and acrylic fiber precursor, the spinning solution must be filtered to remove insoluble impurities, ensuring the cleanliness of the solution and thus improving its spinnability to meet the requirements of continuous and homogenized spinning processes. Because the high-temperature solution contains highly polar organic solvents, the fiber filter cloth has high requirements; its corrosion resistance and interception accuracy must meet the needs of the production process.

[0003] Chinese Patent Publication No. CN201171941Y discloses a filter cloth for a filter press, comprising an upper layer of degreased and bleached cotton cloth, a lower layer of degreased and bleached cotton cloth, and a middle layer of pure cotton non-woven filter element. The upper layer of degreased and bleached cotton cloth is bonded to the middle layer of pure cotton non-woven filter element via an adhesive layer, and the lower layer of degreased and bleached cotton cloth is also bonded to the middle layer of pure cotton non-woven filter element via an adhesive layer. The adhesive layer is made of a mixture of refined cotton and an adhesive. In the prior art, the filter cloth material for filtering spinning raw materials is pure cotton. With prolonged use, the filter cloth will corrode, age, and decompose, resulting in the problem of filter cloth sticking to the filter equipment (such as plates, frames, and screens), which is difficult to clean and may even damage the filter equipment. The fallen aged filter cloth will form new system impurities, contaminating the raw material and reducing the purity of the raw material, thus affecting the subsequent spinning quality.

[0004] In view of this, this utility model is proposed. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a composite filter cloth for a plate and frame filter press for spinning solution filtration. This filter cloth is not easy to age and decompose, has a long service life, avoids the contamination of the raw solution by the fallen aged filter cloth, reduces the frequency of filter cloth replacement, and reduces production costs.

[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0007] A composite filter cloth for a plate and frame filter press for filtering spinning solution includes: a filter layer, an interception layer, and a corrosion-resistant layer arranged sequentially, wherein the filter material of the filter layer is cotton cloth, the filter material of the interception layer is non-woven fabric, and the filter material of the corrosion-resistant layer is PET fiber cloth.

[0008] In this invention, the filtration precision of the filter layer, interception layer, and corrosion-resistant layer is no greater than that of the preceding layer. The filtration precision of adjacent filter layers can be the same, or all three filter layers can have the same filtration precision. However, a more preferred solution is that the filtration precision of each layer gradually decreases. In the above technical solution, the filtration precision of the filter layer, interception layer, and corrosion-resistant layer gradually decreases.

[0009] The filtration precision of the filter layer, interception layer, and corrosion-resistant layer of this invention can also be the same, but a more preferred embodiment is that the filtration precision of each layer gradually decreases.

[0010] In the above technical solution, the filtration accuracy of the filter layer is 1-10um.

[0011] In the above technical solution, the filtering accuracy of the interception layer is 1-5µm.

[0012] In the above technical solution, the filtration accuracy of the corrosion-resistant layer is 1-3 μm.

[0013] In this invention, the average single fiber diameter of the filter layer, interception layer, and corrosion-resistant layer is not greater than that of the previous layer. The average single fiber diameter of two adjacent filter media layers can be the same, or the average single fiber diameter of all three filter media layers can be the same. However, a more preferred solution is that the average single fiber diameter of each layer gradually decreases.

[0014] In the above technical solution, the average diameter of a single fiber in the filter layer, interception layer, and corrosion-resistant layer gradually decreases.

[0015] In the above technical solution, the average diameter of a single fiber in the filter layer is 10-30 μm, the average diameter of a single fiber in the interception layer is 10-20 μm, and the average diameter of a single fiber in the corrosion-resistant layer is 10-15 μm.

[0016] This invention utilizes scientifically selected and rationally distributed filter media of different materials, arranging multiple layers of filter media from coarse to fine. Specifically, the filtration precision and / or average single fiber diameter of the filter layer, interception layer, and corrosion-resistant layer gradually decrease, forming a gradient filtration structure. Through this composite design, the filter cloth can first trap larger particles and then gradually filter smaller impurities, avoiding one-time clogging, extending the service life of the filter cloth, and effectively improving filtration efficiency.

[0017] The filter media in the filter layer is cotton cloth, primarily used to filter larger particles of impurities, serving as a primary filter while also possessing a high dirt-holding capacity. Its large pores can accommodate a large number of larger particles, making it less prone to clogging. The cotton cloth in the filter layer is needle-punched cotton, made from high-purity, high-quality cotton. A needle-punching process is used to thicken and compact the cotton cloth, increasing its thickness. The higher the purity of the raw material and the fewer impurities, the better the filtration effect.

[0018] The interception layer filter material is made of non-woven fabric, which further filters smaller particles that the upper layer failed to intercept, and at the same time can intercept a layer of short cotton fibers that fall off, playing a role in security filtration.

[0019] The corrosion-resistant filter media is made of PET fiber cloth, which performs fine filtration of tiny impurities to ensure the accuracy of the final filtration. At the same time, this layer material has the characteristics of corrosion resistance and non-aging, and can maintain good filtration performance for a long time.

[0020] In the above technical solution, the thickness of the filter layer is 5-10mm, the thickness of the interception layer is 0.2-1mm, and the thickness of the corrosion-resistant layer is 0.2-1mm.

[0021] In the above technical solution, the thickness of the filter layer is 5-8 mm, the thickness of the interception layer is 0.2 mm, and the thickness of the corrosion-resistant layer is 0.2 mm.

[0022] Depending on the condition of the solution to be filtered, multiple layers of cotton cloth can be selected as the filter layer, and / or multiple layers of non-woven fabric as the interception layer, and / or multiple layers of PET fiber cloth as the corrosion-resistant layer, in order to improve the filtration effect.

[0023] PET fiber cloth possesses strong chemical corrosion resistance and excellent high-temperature resistance, capable of withstanding the erosion of highly polar organic solvents such as dimethylacetamide. It also maintains stable physical properties at high temperatures, unlike traditional filter cloths which age, soften, or decompose, leading to impurities shedding or adhering to filtration equipment. The smooth surface of PET fiber cloth also prevents materials, adhesives, and impurities from adhering to it. Therefore, this invention offers significant advantages in the production processes of acrylic and carbon fiber precursors. In the production processes of acrylic and carbon fiber precursors, spinning solutions often contain highly polar organic solvents (such as dimethylacetamide). Traditional filter cloth materials (such as pure cotton) are easily corroded and aged. Using this invention to filter the spinning solution can ensure that the spinning solution can be thoroughly purified, reducing the impact on subsequent spinning processes. It can also prevent the filter cloth from adhering to the filtration equipment after long-term use, effectively solving the problems of filter cloth sticking to the plate and contaminating the spinning solution after aging. At the same time, it extends the service life of the filter cloth (≥200 days) and reduces the frequency of filter cloth replacement. This means that downtime can be reduced in the production process of acrylic and carbon fiber precursors, ensuring that the production line can operate continuously and stably for a longer period of time, reducing production costs and bringing higher economic benefits.

[0024] In the above technical solution, the filter layer, the interception layer, and the corrosion-resistant layer are fixed together on at least one side by sewing.

[0025] This invention can be used as filter cloth in plate and frame filters in carbon fiber production. When applied to a plate and frame filter, the corrosion-resistant layer is in direct contact with the filter screen of the plate and frame filter.

[0026] This invention allows filter media to be stacked together for direct use without additional fixing, or multiple layers of filter media to be fixed together by means such as sewing, edge binding, hot pressing, or gluing. This invention uses a sewing composite method to sequentially sew and fix the filter layer, interception layer, and corrosion-resistant layer together on at least one side. The sewing connection method is simple, has high connection strength, and does not affect the performance of the filter media.

[0027] By adopting the above technical solution, this utility model has the following beneficial effects compared with the prior art.

[0028] This invention has a higher dirt holding capacity, improves the effect of intercepting impurities and filtration, solves the problems of aging, damage and sticking to the plate of traditional filter cloth, and avoids the formation of impurities from aged and decomposed filter cloth that contaminate the spinning solution, thus ensuring the filtration quality of the solution.

[0029] This invention has a longer service life, reduces the frequency of replacement, improves overall production efficiency, reduces production costs, and brings higher economic benefits.

[0030] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings. Attached Figure Description

[0031] The accompanying drawings, as part of this utility model, are used to provide a further understanding of the present utility model. The illustrative embodiments and descriptions of the present utility model are used to explain the present utility model, but do not constitute an undue limitation of the present utility model. Obviously, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0032] Figure 1 This is a cross-sectional schematic diagram of the composite filter cloth;

[0033] Figure 2 This is a schematic diagram of the gradient filtration structure of the composite filter cloth;

[0034] Reference numerals: 1-Filter layer; 2-Interception layer; 3-Corrosion resistant layer.

[0035] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0037] like Figure 1 and Figure 2 As shown, a composite filter cloth for a plate and frame filter press for filtering spinning solution includes: a filter layer 1, an interception layer 2, and a corrosion-resistant layer 3 arranged sequentially. The average single fiber diameter and filtration accuracy of the filter layer 1, the interception layer 2, and the corrosion-resistant layer 3 gradually decrease, so that the composite filter cloth forms a gradient filtration structure.

[0038] Filter layer 1 is mainly used to filter larger particles of impurities, playing a primary filtration role. It also has a high dirt-holding capacity, with its large pores able to accommodate a large number of larger particles of impurities without easily clogging.

[0039] Interception layer 2 further filters smaller particles that were not intercepted by filter layer 1, and also intercepts a layer of short cotton fibers that have fallen off, thus playing a role in security filtration.

[0040] The corrosion-resistant layer 3 performs fine filtration of tiny impurities, ensuring the accuracy of the final filtration. At the same time, the filter material of this layer is PET fiber cloth, which has the characteristics of corrosion resistance and non-aging, and can maintain good filtration performance for a long time.

[0041] in:

[0042] The filtration accuracy of filter layer 1 is 1-10um, the average diameter of a single fiber is 10-30um, and the thickness is 5-10mm;

[0043] The filtration accuracy of the interception layer 2 is 1-5µm, the average diameter of a single fiber is 10-20µm, and the thickness is 0.2-1mm.

[0044] The corrosion-resistant layer 3 has a filtration accuracy of 1-3µm, an average single fiber diameter of 10-15µm, and a thickness of 0.2-1mm.

[0045] Example 1

[0046] (1) A cotton cloth with a thickness of 5 mm, a filtration accuracy of 3 μm, and an average single fiber diameter of 20 μm was used as the filter layer;

[0047] (2) A nonwoven fabric with a thickness of 0.5 mm, a filtration accuracy of 3 μm, and an average single fiber diameter of 20 μm is used as the interception layer;

[0048] (3) A PET fiber cloth with a thickness of 0.5 mm, a filtration accuracy of 1 μm, and an average single fiber diameter of 10 μm is used as a corrosion-resistant layer;

[0049] (4) Sew cotton cloth, non-woven cloth and PET fiber cloth together to form a composite filter cloth.

[0050] Example 2

[0051] (1) A cotton cloth with a thickness of 8 mm, a filtration accuracy of 3 μm, and an average single fiber diameter of 15 μm was used as the filter layer;

[0052] (2) A double-layer nonwoven fabric is used as the interception layer, wherein the thickness of each nonwoven fabric layer is 0.2 mm, the filtration accuracy is 1 μm, and the average diameter of a single fiber is 15 μm.

[0053] (3) A PET fiber cloth with a thickness of 0.2 mm, a filtration accuracy of 1 μm, and an average single fiber diameter of 12 μm is used as a corrosion-resistant layer;

[0054] (4) Sew cotton cloth, non-woven cloth and PET fiber cloth together to form a composite filter cloth.

[0055] Example 3

[0056] (1) A cotton cloth with a thickness of 6 mm, a filtration accuracy of 3 μm, and an average single fiber diameter of 25 μm was used as the filter layer;

[0057] (2) A nonwoven fabric with a thickness of 0.2 mm, a filtration accuracy of 2 μm, and an average single fiber diameter of 20 μm is used as the interception layer;

[0058] (3) A PET fiber cloth with a thickness of 0.2 mm, a filtration accuracy of 1 μm, and an average single fiber diameter of 15 μm is used as a corrosion-resistant layer;

[0059] (4) Sew cotton cloth, non-woven cloth and PET fiber cloth together to form a composite filter cloth.

[0060] Example 4

[0061] (1) A cotton cloth with a thickness of 6 mm, a filtration accuracy of 3 μm, and an average single fiber diameter of 25 μm was used as the filter layer;

[0062] (2) A nonwoven fabric with a thickness of 0.2 mm, a filtration accuracy of 2 μm, and an average single fiber diameter of 20 μm is used as the interception layer;

[0063] (3) A PET fiber cloth with a thickness of 0.2 mm, a filtration accuracy of 1 μm, and an average single fiber diameter of 15 μm is used as a corrosion-resistant layer;

[0064] (4) Sew cotton cloth, non-woven cloth and PET fiber cloth together to form a composite filter cloth.

[0065] Comparative Example 1

[0066] Prepare a regular filter cloth with a thickness of 5mm, a filtration accuracy of 3um, an average single fiber diameter of 15um, and made of pure cotton.

[0067] Comparative Example 2

[0068] Prepare a filter cloth for a filter press with an upper layer of degreased and bleached cotton cloth, a middle layer of pure cotton non-woven filter material, and a lower layer of degreased and bleached cotton cloth.

[0069] The upper degreased and bleached cotton cloth layer has a thickness of 5mm, a filtration accuracy of 3um, and an average single fiber diameter of 20um.

[0070] The thickness of the middle pure cotton non-woven filter layer is 0.2mm, the filtration accuracy is 1um, and the average diameter of a single fiber is 10um;

[0071] The lower layer of degreased and bleached cotton cloth is 0.5 mm thick, has a filtration accuracy of 3 μm, and an average single fiber diameter of 15 μm.

[0072] Summarize:

[0073] The filter cloth conditions of Examples 1-4 and Comparative Examples 1-2 are summarized in Table 1.

[0074] Table 1:

[0075]

[0076] experiment:

[0077] (1) The filter cloths obtained in Examples 1-4 and Comparative Examples 1-2 were installed on a plate and frame filter press to filter the carbon fiber spinning solution. The filter cloths removed after running online for 90 days and 200 days under the same conditions are shown in Table 2.

[0078] Table 2:

[0079]

[0080] in conclusion:

[0081] Experiments show that the traditional filter cloths in Comparative Examples 1-2 all showed signs of aging and damage after 90 days of online operation, resulting in a sticking problem, where the aged filter cloth adhered to the filter screen of the plate and frame filter press and was difficult to clean. The composite filter cloths in Examples 1-4 did not show signs of aging and corrosion after 200 days of high-temperature operation, nor did they exhibit sticking problems. This indicates that the service life of this invention is more than twice that of traditional filter cloths, and it also solves the problems of aged and detached filter cloths contaminating the spinning solution and filter cloth sticking to the filter screen.

[0082] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A composite filter cloth for a plate and frame filter press for filtering spinning solution, characterized in that, The composite filter cloth includes a filter layer, an interception layer, and a corrosion-resistant layer arranged sequentially, wherein the filter material of the filter layer is needle-punched cotton, the filter material of the interception layer is non-woven fabric, and the filter material of the corrosion-resistant layer is PET fiber cloth; the surface of the PET fiber cloth is smooth; the corrosion-resistant layer is in direct contact with the filter screen of the plate and frame filter press; the filtration accuracy and the average value of the single fiber diameter of the filter layer, interception layer, and corrosion-resistant layer gradually decrease.

2. The composite filter cloth of the plate and frame filter press for spinning solution filtration according to claim 1, characterized in that, The filtration precision of the filter layer is 1-10µm.

3. The composite filter cloth for a plate and frame filter press for spinning solution filtration according to claim 1, characterized in that, The filtering accuracy of the interception layer is 1-5µm.

4. The composite filter cloth of the plate and frame filter press for spinning solution filtration according to claim 1, characterized in that, The filtration accuracy of the corrosion-resistant layer is 1-3µm.

5. The composite filter cloth for a plate and frame filter press for spinning solution filtration according to claim 1, characterized in that, The average diameter of a single fiber in the filter layer is 10-30 μm, the average diameter of a single fiber in the interception layer is 10-20 μm, and the average diameter of a single fiber in the corrosion-resistant layer is 10-15 μm.

6. The composite filter cloth for a plate and frame filter press for spinning solution filtration according to any one of claims 1-5, characterized in that, The thickness of the filter layer is 5-10mm, the thickness of the interception layer is 0.2-1mm, and the thickness of the corrosion-resistant layer is 0.2-1mm.

7. The composite filter cloth for a plate and frame filter press for spinning solution filtration according to claim 6, characterized in that, The filter layer has a thickness of 5-8 mm, the interception layer has a thickness of 0.2 mm, and the corrosion-resistant layer has a thickness of 0.2 mm.

8. The composite filter cloth for a plate and frame filter press for spinning solution filtration according to any one of claims 1-5, characterized in that, The filter layer, interception layer, and corrosion-resistant layer are fixed together on at least one side by sewing.

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