Low-linear-density fusible polytetrafluoroethylene continuous filament and preparation method thereof

Abstract

The invention discloses a low-linear-density fusible polytetrafluoroethylene continuous filament and a preparation method thereof, and the preparation method comprises the following steps: adopting fusible polytetrafluoroethylene particles as a raw material, and preparing an initial fusible polytetrafluoroethylene filament through conventional screw melt extrusion; the initial fusible polytetrafluoroethylene filaments are conveyed to a composite hot drafting device, a multi-stage mechanical drafting device and a multi-channel hot air flow processing device are arranged in the composite hot drafting device, and fusible polytetrafluoroethylene drafting filaments are obtained through preparation; the fusible polytetrafluoroethylene filaments are conveyed to a sintering device, and low-linear-density fusible polytetrafluoroethylene continuous filaments are obtained; and winding and forming. The diameter of the fusible polytetrafluoroethylene continuous filaments prepared through the airflow mechanical composite drafting technology is smaller than 50 microns, the linear density is smaller than 5 dtex, the continuous length is larger than 8000 m, and fabric prepared from the continuous filaments through a conventional weaving technology can be used for corrosive liquid filtering materials including strong acid and strong oxidizing liquid filtering materials. The invention discloses strong solvent type liquid filtering materials such as chloroform.

Description

TECHNICAL FIELD

[0001] The present application relates to a polytetrafluoroethylene continuous filament preparation method, a low linear density fusible polytetrafluoroethylene continuous filament and a preparation method thereof, in particular to a low linear density fusible polytetrafluoroethylene continuous filament preparation method based on airflow mechanical composite drafting technology. BACKGROUND

[0002] The rapid development of industry brings great pressure to environmental protection, especially the semiconductor electroplating, chloroform, printing and dyeing industries, which not only consume a large amount of water resources, but also require higher requirements for water purification and harmless treatment for industrial development. The wastewater discharged by such industries is complex in composition, has strong corrosive, oxidizing and solvent properties, and if directly discharged into the environment, it will cause serious damage to water resources and soil. In the prior art, liquid filter materials are used to purify and treat wastewater discharged by such industries. The main structure of the liquid filter material is a non-woven material composed of a reinforced fabric base cloth and functional fibers, wherein the existing reinforced fabric base cloth is mainly made of woven tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (fusible polytetrafluoroethylene) filaments.

[0003] The existing fusible polytetrafluoroethylene filaments for corrosive liquid filter materials mainly rely on foreign imports and are expensive. The domestic fusible polytetrafluoroethylene filament preparation technology is large diameter and multi-filament composite. CN207549531U discloses a fusible polytetrafluoroethylene filament and multi-filament extrusion integrated device, which realizes multi-filament extrusion through the control of the spinning hole structure of the melt extrusion die and the heat stretching and cooling process. This technology has a long process flow and high requirements for the tensile strength of the continuous filament. The existing technology discloses a large-diameter PFA monofilament and its production method. The conventional screw technology is used to add an extrusion aid to PFA particles, and a PFA continuous filament with a diameter of >80μm is prepared by co-extrusion processing. This technology is not suitable for preparing low linear density fusible polytetrafluoroethylene filaments. SUMMARY

[0004] Polytetrafluoroethylene filament is widely used, but the existing technology discloses or sells large diameter high linear density filament, mainly because small diameter low density polytetrafluoroethylene filament is difficult to prepare, is easy to break, that is, the existing technology cannot realize the common promotion of small diameter low density and polytetrafluoroethylene filament length. The application discloses a low linear density fusible polytetrafluoroethylene continuous filament preparation method based on airflow mechanical composite drafting technology, avoids the problem that low linear density fusible polytetrafluoroethylene continuous filament is broken in mechanical thermal drafting, and the fusible polytetrafluoroethylene continuous filament prepared by the application has a diameter of less than 50 microns, a linear density of less than 5 dtex, and a continuous length of more than 10,000 meters, especially the prepared filament has good mechanical strength, and the fabric made of the continuous filament through a weaving process can be used as a corrosive liquid filtering material, including strong acid, strong oxidizing liquid filtering material, chloroform and other strong solvent type liquid filtering materials.

[0005] To achieve the above object, the application adopts the following technical scheme.

[0006] A low linear density fusible polytetrafluoroethylene continuous filament preparation method comprises the following steps: (1) preparing fusible polytetrafluoroethylene into initial fusible polytetrafluoroethylene filament; (2) preparing the initial fusible polytetrafluoroethylene filament through multi-stage mechanical drafting and multi-pass hot airflow treatment to prepare fusible polytetrafluoroethylene drafting filament; (3) sintering the fusible polytetrafluoroethylene drafting filament to prepare low linear density fusible polytetrafluoroethylene continuous filament.

[0007] In the application, the fusible polytetrafluoroethylene includes tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer; the fusible polytetrafluoroethylene is prepared into initial fusible polytetrafluoroethylene filament through screw melting extrusion; the diameter of the initial fusible polytetrafluoroethylene filament is 300-1000 microns, and the continuous length is greater than 8000 meters, preferably greater than 10000 meters.

[0008] In the application, one pass of hot airflow treatment is configured for each stage of mechanical drafting; the number of stages of multi-stage mechanical drafting is 2-6, and the drafting multiple is 2.0-10.0 times. Preferably, the number of stages of multi-stage mechanical drafting is 2-4, and the drafting multiple is 4.0-8.0 times.

[0009] In the application, the temperature of the hot airflow treatment is 140-240 DEG C, and the pressure is 0.5-1.5 MPa; the included angle formed by the hot airflow and the long axis of the initial fusible polytetrafluoroethylene filament is 20-80 DEG, and the movement direction of the hot airflow is the same as the movement direction of the initial fusible polytetrafluoroethylene filament.

[0010] In the application, the sintering adopts hot plate sintering technology, and the temperature is 150-350 DEG C.

[0011] In the present application, the low linear density fusible polytetrafluoroethylene continuous filament is prepared by sintering fusible polytetrafluoroethylene drawn filaments, and then is wound into a shape.

[0012] The present application discloses the low linear density fusible polytetrafluoroethylene continuous filament prepared by the above preparation method.

[0013] The present application discloses the application of the above low linear density fusible polytetrafluoroethylene continuous filament in preparing a filter material.

[0014] The present application discloses a filter material, and the preparation raw material of the filter material comprises the above low linear density fusible polytetrafluoroethylene continuous filament.

[0015] The present application discloses a filtering method, and the raw material comprising the above low linear density fusible polytetrafluoroethylene continuous filament is prepared into a filter material, and then is filtered. For example, the raw material comprising the above low linear density fusible polytetrafluoroethylene continuous filament is prepared into a filter material, and then the filter material is used to filter wastewater, so that the wastewater is purified.

[0016] The present application adopts fusible polytetrafluoroethylene particles with good melt flow performance as raw material, and an initial fusible polytetrafluoroethylene filament with a certain diameter is prepared by a conventional screw melting extrusion technology; the initial fusible polytetrafluoroethylene filament prepared above is transported to a composite hot drawing device, and a plurality of mechanical drawing and a plurality of hot air treatment devices are arranged in the composite device to prepare a fusible polytetrafluoroethylene drawn filament; the fusible polytetrafluoroethylene filament prepared by the composite drawing technology above is transported to a sintering device to prepare a low linear density fusible polytetrafluoroethylene continuous filament; and the low linear density fusible polytetrafluoroethylene continuous filament is wound into a shape.

[0017] Further, fusible polytetrafluoroethylene particles with good melt flow performance are used as raw material, the raw material is tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (also known as fusible polytetrafluoroethylene), the melt index of the raw material is 1-100 g / 10 min, and the particle diameter is less than 4 mm.

[0018] Further, an initial fusible polytetrafluoroethylene filament with a certain diameter is prepared by a conventional screw melting extrusion technology, for example, the number of screw melting heating zones is 3-8, the temperature is 350-400℃, the diameter of the initial fusible polytetrafluoroethylene continuous filament is 300-1000 μm, and the continuous length is greater than 8000 meters, preferably greater than 10000 meters.

[0019] Further, the prepared initial fusible polytetrafluoroethylene filament is transported to a composite hot drawing device, which is configured with multi-stage mechanical drawing and multi-channel hot air treatment device, to prepare fusible polytetrafluoroethylene drawn filament; in the composite hot drawing device, multi-stage mechanical drawing adopts multi-channel drawing rollers with different speeds, and a hot air treatment device is configured after each stage of mechanical drawing, the number of stages of multi-stage mechanical drawing is 2-6, and the filament drawing multiple is 2.0-10.0, and correspondingly, the hot air treatment is 2-6 channels.

[0020] Further, after the initial fusible polytetrafluoroethylene filament is transported to the composite hot drawing device, the composite device is configured with multi-stage mechanical drawing and multi-channel hot air treatment device to prepare fusible polytetrafluoroethylene drawn filament; the hot drawing temperature is 140-240 DEG C, the included angle between the hot drawing air flow and the long axis of the filament is 20-80 DEG, the movement direction of the hot drawing air flow is the same as that of the filament, the hot air flow is high-pressure hot air, the temperature is preferably 160-230 DEG C, and the pressure is 0.5-1.5 MPa.

[0021] Further, the fusible polytetrafluoroethylene filament prepared by the composite drawing technology is transported to a sintering device to prepare low linear density fusible polytetrafluoroethylene continuous filament; the sintering device adopts a hot plate sintering technology, the temperature is 150-350 DEG C, and the time is 0.5-1 min.

[0022] Further, winding forming, the tension of the continuous filament is <10 N, and the winding speed is 0.6-39 m / min.

[0023] The fusible polytetrafluoroethylene continuous filament prepared by the airflow mechanical composite drawing technology has a diameter of less than 50 microns, a linear density of less than 5 dtex, and a continuous length of more than 8000 meters, preferably more than 10000 meters, preferably, the fusible polytetrafluoroethylene continuous filament prepared by the airflow mechanical composite drawing technology has a diameter of 10-40 microns and a linear density of 2-4.5 dtex; further, the fabric made by weaving the above continuous filament can be used for corrosive liquid filtering material, including strong acid, strong oxidizing liquid filtering material, chloroform and other strong solvent type liquid filtering material.

[0024] This invention proposes a method for preparing low-linear-density fusible polytetrafluoroethylene (PTFE) continuous filaments based on airflow-mechanical composite drawing technology. The method comprises the following steps: Using conventional screw melt extrusion technology, fusible PTFE particles with high melt flow properties are fed into a screw extruder for conventional continuous melt extrusion. The melt flows through a spinneret to obtain initial fusible PTFE continuous filaments. These filaments are then conveyed to an airflow-mechanical composite thermal drawing device for multi-stage continuous drawing, followed by sintering and other processing to form the final product, which is then wound into shape. This invention, based on conventional screw extrusion technology, employs a high-pressure hot airflow combined with mechanical composite thermal drawing technology to draw the initial fusible PTFE continuous filaments to prepare low-linear-density fusible PTFE continuous filaments. The fusible polytetrafluoroethylene continuous filaments prepared by airflow mechanical composite stretching technology have a diameter ≤50μm, a linear density of less than 5dtex, and a continuous length >10000 meters. The fabrics made from these continuous filaments through weaving can be used as filtration materials for corrosive liquids, including filtration materials for strong acids, strong oxidizing liquids, and strong solvent-based liquids such as chloroform.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention combines conventional screw extrusion process with airflow combined with mechanical thermal stretching technology to achieve continuous stretching of fusible polytetrafluoroethylene filaments, thereby preparing fusible polytetrafluoroethylene filaments with low diameter and low linear density.

[0026] 2) This invention uses screw melt extrusion technology to continuously prepare initial fusible polytetrafluoroethylene filaments, which are then continuously processed by airflow mechanical composite thermal stretching technology to obtain low linear density fusible polytetrafluoroethylene continuous filaments with a continuous length of more than 10,000 meters.

[0027] 3) The present invention provides a method for preparing low linear density fusible polytetrafluoroethylene continuous filaments based on airflow mechanical composite drawing technology. The process is short, simple to operate, and has low energy consumption. The prepared low linear density fusible polytetrafluoroethylene continuous filaments can be used as materials for purifying corrosive industrial wastewater, which can reduce material costs. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall process of the present invention.

[0029] Figure 2 This is a schematic diagram of the process of the airflow mechanical composite stretching technology of the present invention.

[0030] Figure 3 These are the DSC curves of PFA filaments stretched 4 times at different temperatures.

[0031] Figure 4 This is a photograph of the actual product from Example 1. Detailed Implementation

[0032] This invention discloses a method for preparing low linear density fusible polytetrafluoroethylene continuous filaments, comprising the following steps: (1) Using fusible polytetrafluoroethylene particles as raw material, a certain diameter of initial fusible polytetrafluoroethylene filaments are prepared by conventional screw melt extrusion technology; (2) The initial fusible polytetrafluoroethylene filaments obtained above are transported to a composite hot drawing device, which is equipped with a multi-stage mechanical drawing and a multi-stage hot air flow treatment device to prepare fusible polytetrafluoroethylene drawn filaments. (3) The fusible polytetrafluoroethylene filaments prepared by the above composite drawing technology are transported to the sintering device to prepare low linear density fusible polytetrafluoroethylene continuous filaments. (4) Winding and shaping.

[0033] In step (1) of this invention, fusible polytetrafluoroethylene particles with good melt flow properties are used as raw materials. The raw material is a tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (also known as fusible polytetrafluoroethylene). The melt index of the raw material is 1~100g / 10min (320℃ / 5Kg), and the particle diameter is less than 4mm.

[0034] In step (2) of this invention, a certain diameter of initial fusible polytetrafluoroethylene filament is prepared by conventional screw melt extrusion technology. The number of screw melt heating zones is 3 to 8, the temperature is 350℃ to 400℃, the diameter of the initial fusible polytetrafluoroethylene continuous filament is 300 to 1000 μm, and the continuous length is >8000 meters.

[0035] In step (2) of this invention, the initial fusible polytetrafluoroethylene (PTFE) filament obtained in step (1) is transported to a composite hot drawing device. This composite device is equipped with multi-stage mechanical drawing and multi-stage hot air flow treatment devices to prepare fusible PTFE drawn filaments. In the composite hot drawing device, the multi-stage mechanical drawing uses multiple drawing rollers with different speeds. In each stage of mechanical drawing, a hot air flow treatment device is configured. The number of stages of multi-stage mechanical drawing is 2 to 6, and the filament drawing ratio is 2.0 to 10.0 times (the drawing ratio refers to the drawing ratio of each stage), for example, the total drawing ratio of the filament is 8 times. Preferably, in the multi-stage mechanical drawing, the drawing ratio of each stage is gradually increased to form a gradient drawing ratio increase.

[0036] In step (2) of this invention, the initial fusible polytetrafluoroethylene filament obtained in step (1) is transported to a composite hot drawing device. The composite device is equipped with a multi-stage mechanical drawing and a multi-stage hot air flow treatment device to prepare fusible polytetrafluoroethylene drawn filament. The hot drawing temperature is 140℃~240℃, the pressure is 0.5~1.5 MPa, the angle between the hot drawing air flow and the long axis of the filament is 20°~80°, and the direction of the hot drawing air flow is the same as the direction of the filament.

[0037] In step (3) of this invention, the fusible polytetrafluoroethylene drawn filaments obtained in step (2) are transported to a sintering device and sintered to obtain low linear density fusible polytetrafluoroethylene continuous filaments; the sintering device adopts hot plate sintering technology, with a temperature of 150℃~350℃ and a time of 0.5~1min.

[0038] In step (4) of this invention, the continuous filament is wound and the tension is <10N, and the winding speed is 0.6~39m / min.

[0039] This invention discloses a method for preparing low-linear-density fusible polytetrafluoroethylene (PTFE) continuous filaments based on airflow-mechanical composite drawing technology. The fusible PTFE continuous filaments prepared by airflow-mechanical composite drawing technology have a diameter ≤50μm, a linear density of less than 5dtex, and a continuous length >10000 meters. At the same time, the fabric made from the continuous filaments by weaving process can be used as a filter material for corrosive liquids, including filter materials for strong acids, strong oxidizing liquids, and strong solvent-based liquids such as chloroform.

[0040] In this invention, the low linear density fusible polytetrafluoroethylene continuous filament has the following characteristics: low linear density refers to a density of less than 5 dtex, preferably less than 4.5 dtex, further less than 4.0 dtex, and further less than 3.5 dtex; continuous filament refers to a single filament length greater than 8000 meters, preferably greater than 10000 meters. Furthermore, the diameter of the low linear density fusible polytetrafluoroethylene continuous filament is less than 50 μm, preferably not greater than 40 μm, for example, 10~30 μm.

[0041] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein. The raw materials used in the present invention are existing products, and the specific preparation operations and performance testing are all conventional techniques. Example 1

[0042] like Figure 1 As shown, a method for preparing low linear density fusible polytetrafluoroethylene continuous filaments based on airflow-mechanical composite drawing technology includes the following steps: (1) Initial fusible polytetrafluoroethylene filaments were obtained by conventional screw melt extrusion using fusible polytetrafluoroethylene granules with good melt flow properties as raw materials. The raw material was tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA, also known as fusible polytetrafluoroethylene, AP-201), with a melt index of 10 g / 10 min, which is an existing product. The screw had four melting heating zones with temperatures of 360℃, 370℃, 380℃ and 390℃, and a screw speed of 15 r / min. The diameter of the initial fusible polytetrafluoroethylene continuous filament was 400 μm and the strength was 0.121 cN / dtex. (2) The initial fusible polytetrafluoroethylene filaments obtained above are conveyed to the composite hot drawing device (see Figure 2 In this composite hot drawing device, multi-stage mechanical drawing employs multiple drawing rollers with different speed configurations. A hot airflow treatment device is configured after each stage of mechanical drawing. The number of stages of multi-stage mechanical drawing is 3, and the filament drawing ratio is 8 times. Specifically, the first stage drawing ratio is 2 times, the second stage drawing ratio is 2 times, and the third stage drawing ratio is 2 times. The hot airflow uses compressed hot air at a temperature of 140℃ and a pressure of 0.8 MPa. The angle between the hot drawing airflow and the long axis of the filament is 30°, and the direction of the hot airflow is the same as the direction of the filament. The initial input speed of the fusible polytetrafluoroethylene filament is 1.0. (3) The fusible polytetrafluoroethylene filaments prepared by the above composite drawing technology are transported to the sintering device to prepare low linear density fusible polytetrafluoroethylene continuous filaments; the sintering device adopts hot plate sintering technology, the temperature is 200℃ and the time is 45s; (4) Winding and forming, the tension of the continuous filament is 4N, and the winding speed is 4.5m / min.

[0043] The fusible polytetrafluoroethylene continuous filaments prepared by the above-mentioned airflow mechanical composite stretching technology have a linear density of 3.42 dtex and a continuous length of 12,000 meters. The fabrics made from them can be used as filter materials for corrosive liquids, including filter materials for strong acids, strong oxidizing liquids, and strong solvent-based liquids such as chloroform. Specifically, this is a conventional technology.

[0044] Example 2

[0045] Referring to Example 1, the hot air temperature in step (2) was changed, while the rest remained the same, to prepare low linear density fusible polytetrafluoroethylene continuous filaments (PFA filaments), with the following properties:

[0046] Figure 3 The DSC curves of PFA filaments at different temperatures with an 8-fold draw are shown. Example 3

[0047] Referring to Example 1, the hot air temperature and draw ratio in step (2) were changed, while the rest remained the same, to prepare a low linear density fusible polytetrafluoroethylene continuous filament with a linear density of 2.18 dtex and the following properties:

[0048] As can be seen, the present invention uses high-pressure hot air assisted mechanical drawing at 120℃-220℃, especially 140℃-200℃. This composite drawing can not only effectively prepare low linear density polytetrafluoroethylene filaments with a length of more than 10,000 meters, but also has good mechanical properties and is suitable for corrosive liquid filtration materials.

[0049] Comparative Example 1 Referring to Example 1, the hot airflow treatment is omitted, i.e., two-stage mechanical drawing at room temperature is performed, and everything else remains the same. The diameter of the prepared filament is 350 micrometers, which is not low linear density. Furthermore, two-stage mechanical drawing at room temperature is performed eight times, and the diameter of the prepared filament is 202 micrometers, which is not low linear density. However, filament breakage occurs during the production process, and the length of a single filament of 8000 meters cannot be achieved.

[0050] Comparative Example 2 Referring to Example 1, using atmospheric pressure hot airflow treatment (i.e., maintaining temperature but omitting high pressure, otherwise the process remains the same), the resulting filament diameter is 220 micrometers, which is not low linear density. Further, using atmospheric pressure hot airflow treatment with two stages of mechanical drawing (8 times), the resulting filament diameter is 113 micrometers, which is not low linear density, and the process results in filament breakage, failing to achieve a single filament length of 8000 meters.

[0051] Comparative Example 3 Referring to Example 1, only hot airflow treatment was used, i.e. mechanical stretching was omitted (the three sets of rollers had the same speed), and everything else was the same. The diameter of the prepared filament was 480 micrometers, which was not low linear density.

[0052] Comparison Example Referring to Example 1, a first-stage mechanical drawing was used, followed by a hot airflow treatment device. The drawing ratio was 8 times, and everything else was the same. The resulting filament had a diameter of 180 micrometers and was not low linear density.

[0053] In existing technologies, the diameter of mainstream polytetrafluoroethylene (PTFE) filaments all exceed 100 μm, and no products with a continuous length exceeding 8000 meters and a diameter less than 100 μm have been found. This invention employs a novel manufacturing process and discloses a method for preparing low-linear-density fusible PTFE continuous filaments based on airflow-mechanical composite drawing technology. The fusible PTFE continuous filaments prepared by airflow-mechanical composite drawing technology have a diameter ≤50 μm, a linear density below 5 dtex, and a continuous length >10000 meters. Furthermore, the fabrics made from these continuous filaments through a weaving process can be used as filtration materials for corrosive liquids, including strong acids, strong oxidizing liquids, and strong solvents such as chloroform.

[0054] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for producing a low linear density, melt-processable polytetrafluoroethylene continuous filament, characterized by, The method comprises the following steps: (1) preparing initial fusible polytetrafluoroethylene filaments from fusible polytetrafluoroethylene; (2) preparing fusible polytetrafluoroethylene drawn filaments by subjecting the initial fusible polytetrafluoroethylene filaments to multi-stage mechanical drawing and multi-pass hot air flow treatment; (3) preparing low linear density fusible polytetrafluoroethylene continuous filaments by sintering the fusible polytetrafluoroethylene drawn filaments.

2. The process for producing low linear density, melt-processable polytetrafluoroethylene continuous filaments according to claim 1, characterized in that, The fusible polytetrafluoroethylene comprises tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer; the fusible polytetrafluoroethylene is prepared into initial fusible polytetrafluoroethylene filaments by screw melting extrusion; the initial fusible polytetrafluoroethylene filaments have a diameter of 300-1000 μm and a continuous length of greater than 8000 meters.

3. The process for producing low linear density continuous melt-processable polytetrafluoroethylene filament according to claim 1, characterized in that, One pass of hot air flow treatment is configured for each stage of mechanical drawing; the number of stages of multi-stage mechanical drawing is 2-6, and the drawing multiple is 2.0-10.0 times.

4. The process for producing low linear density, melt-processable polytetrafluoroethylene continuous filaments according to claim 1, characterized in that, The temperature of the hot air flow treatment is 140-240 °C, and the pressure is 0.5-1.5 MPa; the included angle formed between the hot air flow and the long axis of the initial fusible polytetrafluoroethylene filaments is 20-80 °, and the movement direction of the hot air flow is the same as the movement direction of the initial fusible polytetrafluoroethylene filaments.

5. The process for producing low linear density, melt-processable polytetrafluoroethylene continuous filaments according to claim 1, characterized in that, The sintering adopts hot plate sintering technology, and the temperature is 150-350 °C.

6. The process for producing low linear density, melt-processable polytetrafluoroethylene continuous filaments according to claim 1, characterized in that, The low linear density fusible polytetrafluoroethylene continuous filaments have a diameter of less than 50 μm, a linear density of less than 5 dtex, and a continuous length of greater than 8000 meters.

7. Low linear density fusible polytetrafluoroethylene continuous filaments prepared by the method according to claim 1.

8. Use of the low linear density fusible polytetrafluoroethylene continuous filaments according to claim 7 in preparing filter materials.

9. A filter material, characterized by The filter materials are prepared from the low linear density fusible polytetrafluoroethylene continuous filaments according to claim 7.

10. A filtration method characterized by, Raw materials comprising the low linear density fusible polytetrafluoroethylene continuous filaments according to claim 7 are prepared into filter materials, which are then filtered.

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