CN114232109B - Method for preparing polyether ketone fiber based on nondestructive dissolution wet method - Google Patents

Abstract

The invention discloses a method for preparing a polyether ketone fiber based on a nondestructive dissolution wet method. The preparation method of the invention comprises the following steps: 1. dissolving the polyetherketoneketone in a fluorine-based or chlorine-based polar solvent at room temperature in a nondestructive manner to obtain a uniform polyetherketoneketone solution spinning solution; 2. carrying out wet spinning on the spinning solution, injecting the spinning solution into a coagulating bath through a needle head with a narrow diameter and a large length-diameter ratio for molding, and then carrying out drafting, drying and winding to obtain the as-spun polyether ketone fiber; 3. and carrying out multistage hot drawing on the as-spun polyether-ketone fiber, then winding and collecting, and carrying out high-temperature treatment and shaping to obtain the high-performance polyether-ketone fiber. The invention adopts fluorine-based or chlorine-based polar solvent to realize the nondestructive dissolution of the polyether ketone, so as to form uniform and stable colloid solution; in the spinning process, the polyether ketone forms a firm network structure under the shearing action, so that the shape and the volume of the fiber can be kept unchanged; the obtained polyether-ketone fiber has the excellent characteristics of light weight, high strength, high temperature resistance, flame retardance and the like.

Description

A method for preparing polyether ketone ketone fiber based on non-destructive dissolution wet method

technical field

The invention relates to a method for preparing polyether ketone ketone fibers based on a non-destructive dissolution wet method, and belongs to the technical field of preparation of functional thermal fibers.

Background technique

Polymer fibers are an important part of polymer materials and play a very important role in social life and industrial production. Among them, as a kind of special fiber, the high-temperature-resistant fiber that can be used for a long time above 180°C or maintain good physical properties for a certain period of time at a higher temperature has received high attention.

With the rapid development of my country's aerospace, fire protection, nuclear industry and other fields, the demand for high-temperature-resistant special fibers is increasing, and it is urgent to further optimize their comprehensive properties; while existing thermosetting resins have insufficient toughness, and high-temperature-resistant thermoplastic resins have fibers Problems such as difficulty in chemicalization limit the development of high-temperature-resistant special fibers.

Among the currently commercialized thermoplastic special engineering plastics, polyaryletherketone polymers have the highest heat resistance grade. Polyaryletherketone is a class of semi-crystalline thermoplastics with low density, high mechanical properties, high temperature thermal stability, electrical insulation and chemical corrosion resistance. In the polyaryletherketone family, polyetheretherketone and polyetherketoneketone are the most widely used. In comparison, polyether ketone ketone contains more ketone bonds, and there are differences in the proportion of p-benzene and m-benzene in the molecular structure, with higher glass transition temperature and melting temperature, wider thermal control window and better The mechanical properties have received more extensive attention in recent years. The development of high-temperature special fibers with high mechanical properties based on polyether ketone ketone is of great significance to the transformation and upgrading of my country's high-performance fiber industry, and will also have broad application space in many fields.

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The effect of meltspinning process parameters on the spinnability of polyetheretherketone.J.Appl.Polym.Sci.2012,126(5),1564；文献6：邓德鹏,李云龙,贾远超,王荣海,张清新,刘勇.静电纺丝制备聚醚酮酮超细纤维.工程塑料应用2016,44(4),44；文献7：栾加双,许治平,王贵宾,张梅,张淑玲,李永刚,盖须召,杨砚超,马亚莉.一种聚醚醚酮短纤纱及其制备方法.中国发明专利ZL201710052321.X)。From the perspective of polymer spinnability, because polyaryletherketone polymers generally have problems such as strong solvent resistance, high melting temperature, and poor melt fluidity, it is not only difficult to realize wet spinning, but also directly adopts melt spinning Technology also faces many difficulties. The current main solution is to reduce the melt viscosity by blending polyaryletherketone with inorganic lubricants, polyesters, etc. to improve processing performance, but the mechanical properties of the fibers are also reduced due to blending. Another method is to improve its dissolving ability by means of sulfonation, chloromethylation, ring-opening polymerization, multi-component copolymerization, etc., and use a solution method for spinning. However, the chemical modification of the polymer destroys its original structure, resulting in a significant decrease in the heat resistance, mechanical properties or chemical corrosion resistance of the polymer. Therefore, for a long time, the preparation method of polyaryletherketone fiber is still based on melt extrusion and its derivative process (such as melt electrospinning) (document 1: MHGDeeg.Process of making an aromaticpolyetherketone fiber product.US patent 1985, US4747988; Document 2: Wang Guibin, Zhang Haibo, Ren Dianfu, Zhang Yunhe, Guan Shaowei, Jiang Zhenhua, Zhang Shuling, Wu Zhongwen. Spinning grade polyether ether ketone resin special material and its preparation method. Chinese invention patent ZL200810050213.X; Document 3: Wang Guibin, Ye Guangdou, Zhang Shuling, Jiang Zhenhua, Chen Xun, Guan Shaowei, Zhang Yunhe, Zhang Haibo, Yang Yanhua, Wu Zhongwen. Preparation method of polyetheretherketone fiber by melt spinning and thermal stretching. Chinese invention patent ZL200810050363.0; Document 4: RIShekar, TMKotresh, PMDRao, K.Kumar.Properties of high modulus PEEK yarns for aerospace applications.J.Appl.Polym.Sci.2009,112(4),2497; Literature 5:V.

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The effect of meltspinning process parameters on the spinnability of polyetheretherketone. J.Appl.Polym.Sci.2012, 126(5), 1564; Literature 6: Deng Depeng, Li Yunlong, Jia Yuanchao, Wang Ronghai, Zhang Qingxin, Liu Yong. Electrospinning preparation Polyether ketone ketone superfine fiber. Engineering Plastics Application 2016, 44(4), 44; Literature 7: Luan Jiashuang, Xu Zhiping, Wang Guibin, Zhang Mei, Zhang Shuling, Li Yonggang, Gai Xuzhao, Yang Yanchao, Ma Yali. A Polyether ether ketone spun yarn and its preparation method. Chinese invention patent ZL201710052321.X).

In addition, for polyetherketoneketone fiber and polyetherketoneketone composite fiber, so far only Arkema France, Arkema Co., Ltd. (USA) and Teijin Aramid Co., Ltd. (Netherlands) have applied for related invention patents in China , wherein: Patent CN102333910A discloses a method for preparing polyether ketone ketone composite fibers by melt spinning, dispersing multi-walled nanotubes containing carbon, nitrogen, boron, phosphorus, silicon, tungsten and other elements into polyether ketone ketone In the matrix, polyether ketone ketone composite fibers are prepared by melt spinning; authorized patent 201080007055.5 provides a method for preparing composite fibers containing polyether ketone ketone and mineral nanotubes, and various mineral nanotubes are mixed by melt blending. The tube is mixed with the polyether ketone ketone matrix, and then the composite fiber is prepared by melt spinning; the patent CN110249083A is currently the only Chinese invention patent that uses wet spinning to prepare the polyether ketone ketone fiber, and it is PCT international patent WO 2018/087121 in China's application uses concentrated sulfuric acid to dissolve polyether ketone ketone to obtain a spinning stock solution, and makes the spinning stock solution pass through a spinneret into a coagulation bath to prepare polyether ketone ketone fibers. However, there are still a series of technical problems in this method that limit its development and application: 1) The dissolution of polyether ketone ketone in concentrated sulfuric acid is actually the sulfonation process of polymers (document 1: R.Y.M.Huang, P.Shao, C.M.Burns, X.Feng.Sulfonation of poly(ether etherketone)(PEEK):Kinetic study and characterization.J.Appl.Polym.Sci.2001,82(11),2651; Document 2: B.Li,T.Liu,Z.C.W.Tang , J.Jia, W.-H.Zhong.Novel hydration induced flexible sulfonated poly(etherketoneketone)foam with super dielectriccharacteristics.J.Mater.Chem.2011,21(35),13546), polyetherketoneketone has been A sulfonation reaction has occurred, which has a great impact on the properties of the fiber obtained by spinning; 2) The dissolution process of polyether ketone ketone in concentrated sulfuric acid needs to be supplemented by an additional mechanical mixing process. For example, the patent recommends the use of a kneader or Extruder is used to promote the mixing process, which means that it is still difficult to achieve uniform mixing or dissolution; 3) The spinning dope is preferably carried out at a temperature of 50 to 90 ° C. On the one hand, this temperature range will further promote the polyether ketone ketone Sulfonation, on the other hand, requires additional temperature control equipment, which brings difficulties to the stability of wet spinning; 4) there is residual acid in the polyether ketone ketone fiber obtained by wet spinning, which needs to be improved by increasing the temperature of the coagulation bath. 5) The uniformity of the obtained fiber structure is poor, and the mechanical strength is lower than 80MPa, which is difficult to be widely used. Based on the above problems, it is urgent to develop efficient and stable wet spinning to prepare high-performance PEEK fibers.

Contents of the invention

The technical problem solved by the present invention is: currently there is only related technology for preparing polyether ketone ketone (composite) fibers by melt spinning, and the wet spinning realized by using concentrated sulfuric acid is a sulfonation method based on polyether ketone ketone polymers. , the dissolved polyether ketone ketone is sulfonated polyether ketone ketone, so there is no related technology for wet spinning by non-destructive dissolution of polyether ketone ketone. In addition, the above spinning methods are carried out at high temperatures or require the introduction of a mechanical mixing process. Not only are the steps cumbersome and costly, but the resulting fibers also have problems such as poor structural uniformity, low strength, and poor performance.

In order to solve the above technical problems, the present invention provides a method for preparing polyether ketone ketone fibers based on non-destructive dissolution, comprising the following steps:

Step 1: Use fluorine-based or chlorine-based polar solvents to dissolve polyether ketone ketone without damage to obtain spinning dope;

Step 2: Wet spinning the spinning stock solution obtained in Step 1, injecting it into a coagulation bath for coagulation and molding, and then pre-drawing, drying, and winding to obtain as-spun polyether ketone ketone fibers;

Step 3: The as-spun polyether ketone ketone fiber obtained in step 2 is wound and collected after multi-stage thermal drawing, and then heat-treated and shaped to obtain a polyether ketone ketone fiber.

Preferably, in the polyether ketone ketone in the step 1, the molar ratio of the p-phenyl position structure to the ortho-phenyl position structure (referred to as the p-position and ortho-position structure ratio, or T/I ratio) is 50:50, 60: 40, 70:30, 80:20 or 100:0, the polyether ketone ketone is a powder with a particle size ≤ 300 μm.

Preferably, the fluorine-based polar solvent in step 1 is trifluoroacetic acid and/or 3,3,3-trifluoro-2,2-dimethylpropionic acid; the chlorine-based polar solvent is p-chloro At least one of phenol, dichloroacetic acid and dichloropropionic acid.

More preferably, the fluorine-based polar solvent is trifluoroacetic acid, and the chlorine-based polar solvent is p-chlorophenol.

Preferably, the process parameters for dissolving in step 1 are: stirring speed 1200-1800rpm, stirring time 6-12h, stirring temperature 25-50°C; the concentration of polyether ketone ketone in the spinning stock solution is 5-22wt% .

Preferably, the wet spinning in step 2 adopts a needle with a narrow diameter and a large aspect ratio, the inner diameter of which is 0.1-0.5mm, and the length is 50-100mm; the process parameters of the injection are: extrusion rate 0.05 ～2mL/min, extrusion temperature is 25～30℃.

Preferably, the coagulation bath in step 2 is water or ethanol, wherein, when trifluoroacetic acid, 3,3,3-trifluoro-2,2-dimethylpropionic acid, dichloroacetic acid, dichloropropane When acid is used as solvent, water is preferred, and when p-chlorophenol is selected as solvent, ethanol is preferred.

Preferably, the temperature of the coagulation bath in the step 2 is 5-40° C., and the time required for the molding is 0.5-2 minutes.

More preferably, the temperature of the coagulation bath is 25-30°C.

Preferably, the pre-drawing in the step 2 is specifically: taking the polyether ketone ketone fiber obtained by coagulation molding out of the coagulation bath and then passing through 3 to 5 guide rails for drafting, the drafting ratio is 1 to 2 times, and the drafting The time is 1 to 5 minutes, so that the fibers are naturally dried, pre-drawn and collected by winding.

Preferably, the thermal drawing in step 3 is to thermally draw the as-spun polyether ketone ketone fiber obtained in step 2 using a horizontal tube furnace, and the length of the furnace body of the horizontal tube furnace is 50-90 cm , the hot drawing adopts three-stage hot drawing, and the specific process parameters are: the first-stage drawing temperature is 200-220°C, the drawing ratio is 2-3.5 times, the second-stage drawing temperature is 230-250°C, the drawing The multiple is 1.5-2 times, the third-stage drawing temperature is 240-260°C, and the drafting multiple is 1.5-2 times.

Preferably, the temperature of the heat treatment in step 3 is 240-300° C., and the time is 1-5 hours.

More preferably, the temperature of the heat treatment is 250-280° C., and the time is 1.5-2 hours.

The present invention also provides the polyether ketone ketone fiber prepared by the above method for preparing polyether ketone ketone fiber based on non-destructive dissolution, the mass density of the polyether ketone ketone fiber is lower than 0.9 g/cm ³ , and the porosity is higher than 30 %, the tensile breaking strength is higher than 600MPa, the thermal weight loss temperature is higher than 450°C, and the flame retardant grade is V-0.

Design idea of the present invention is:

(1) The present invention uses fluorine-based or chlorine-based polar solvents to dissolve polyether ketone ketone without damage, realizing the true dissolution of polyether ketone ketone, avoiding the sulfonation reaction caused by dissolving polyether ketone ketone with concentrated sulfuric acid, The excellent physical properties of polyether ketone ketone can be fully maintained in the fiber;

(2) The polyether ketone ketone solution forms a firm network structure under the shearing action of the wet spinning process, combined with the rigidity of its molecule itself, making the polyether ketone ketone fiber forming process (solvent and polyether ketone ketone occur during the forming process) phase separation) can keep the fiber shape and volume unchanged, which is more conducive to the generation of phase separation-induced microporous structure;

(3) Polymer molecules in polyether ketone ketone fibers not only build a dense network structure, but also form a rich microporous structure, thus realizing the organic integration of many properties, such as light weight, high strength, high temperature resistance, flame retardant wait.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention dissolves polyether ketone ketone non-destructively with fluorine-based or chlorine-based polar solvents, and prepares it by adjusting the concentration of spinning stock solution, needle specification, extrusion rate, coagulation bath type, and pre-drawing rate in the wet spinning process. As-spun polyether ketone ketone fiber, and then heat-drawn and high-temperature heat-setting treatment to obtain high-performance polyether ketone ketone fiber, different from other polymers that shrink significantly in fiber volume during wet spinning, polyether ketone The unique molecular rigidity and entanglement characteristics of ketones keep the fiber volume unchanged during the phase separation process of fiber forming, thereby constructing a rich microporous structure in the fiber and further optimizing and regulating it during the thermal drawing process; the preparation of the present invention The obtained polyether ketone ketone fiber can simultaneously have excellent properties such as light weight, high strength, high temperature resistance, and flame retardancy.

2. Since polyarylether ketone polymers are generally difficult to dissolve, the related wet spinning process is very scarce, and its higher melting temperature also brings many difficulties to melt spinning. The present invention realizes polyether ketone The new breakthrough of ketone wet spinning has realized an efficient and stable preparation process. At the same time, the fiber microstructure has sufficient control space, which provides the possibility to develop various types of fiber products and has broad application prospects.

Description of drawings

Fig. 1 is the spinning stock solution of step 1 gained in the embodiment 1;

Fig. 2 is the as-spun polyether ketone ketone fiber that step 3 gains among the embodiment 1;

Fig. 3 is the heat-set polyether ketone ketone fiber of step 5 gained in the embodiment 1;

Fig. 4 is the scanning electron microscope picture of the cross section of the polyether ketone ketone fiber prepared in embodiment 1;

Fig. 5 is the mechanical test result of the polyether ketone ketone fiber prepared in embodiment 1;

Fig. 6 is the thermal weight loss test result of the polyether ketone ketone fiber prepared in embodiment 1 under air environment;

Fig. 7 is the flame retardant test result of the polyether ketone ketone fiber prepared in Example 1.

Detailed ways

In order to make the present invention more comprehensible, preferred embodiments are described in detail as follows.

Example 1

This embodiment provides a method for preparing polyether ketone ketone fibers based on a non-destructive dissolution wet method, which specifically includes:

1) First prepare a polyether ketone ketone solution, dissolve polyether ketone ketone (T/I ratio 60:40) in trifluoroacetic acid at room temperature (25°C), the concentration is 12.5wt%, stirring speed 1500rpm, stirring After 6 hours, a uniform and stable spinning solution was obtained, as shown in Figure 1.

2) Using an injection needle with an inner diameter of 0.15 mm and a length of 60 cm, inject the polyether ketone ketone solution into a pure water coagulation bath at the same room temperature at room temperature, and the extrusion rate is 0.2 mL/min. The time that the fiber passes in the coagulation bath is 50s.

3) Lead the solidified fiber out of the coagulation bath, pass through 5 guide rails, and carry out pre-drawing under the action of traction. The drafting ratio is 1.2 times, and the drafting time is 2 minutes. After drafting, it is directly collected on the reel to obtain natural fiber. Dry as-spun polyetherketoneketone fiber, as shown in Figure 2.

4) The as-spun polyether ketone ketone fiber is exported from the reel, subjected to thermal drawing treatment through a horizontal tube furnace, and then collected on another reel. A tube furnace with a length of 80cm is adopted, and three-stage (secondary) hot drawing is adopted, wherein the first-stage drawing temperature is 210°C, and the drafting ratio is 2 times, and the second-stage drafting temperature is 240°C, and the drafting ratio is 2 times , The third stage drawing temperature is 260°C, and the drawing ratio is 1.5 times.

5) Put the hot-drawn polyether ketone ketone fibers together with the reel into a hot oven for high-temperature heat-setting treatment. The heat-setting temperature is 280 ° C, and the heat-setting time is 1.5 hours to obtain heat-set polyether ketone Ketone fibers, as shown in Figure 3.

The polyether ketone ketone fiber obtained through the above steps has a uniform diameter of 52 μm, a mass density of 0.85 g/cm ³ (corresponding to a porosity of 34.6%), a tensile breaking strength of 650 MPa, and a thermal weight loss temperature higher than 455 ° C. It is flame retardant Grade V-0 grade. Figures 4 to 7 show the cross-sectional scanning electron microscope photos, mechanical test curves, weight loss test curves and flame retardant test results of the fibers.

Example 2

This embodiment provides a method for preparing polyether ketone ketone fibers based on a non-destructive dissolution wet method, which specifically includes:

1) First prepare a polyether ketone ketone solution, dissolve polyether ketone ketone (T/I ratio 60:40) in trifluoroacetic acid at a temperature of 40°C, the concentration is 22wt%, the stirring speed is 1800rpm, and the stirring time is 6h. A uniform and stable spinning dope is obtained.

2) Using an injection needle with an inner diameter of 0.5 mm and a length of 50 cm, inject the polyether ketone ketone solution into a pure water coagulation bath at a temperature of 40° C. at room temperature, and the extrusion rate is 2 mL/min. The elapsed time of the fiber in the coagulation bath was 2 min.

3) Lead the solidified fiber out of the coagulation bath, pass through 5 guide rails, and carry out pre-drawing under the action of traction. The drafting ratio is 1.1 times, and the drafting time is 2 minutes. After drafting, it is directly collected on the reel to obtain natural fiber. Dry as-spun polyetherketoneketone fibers.

4) The as-spun polyether ketone ketone fiber is exported from the reel, subjected to thermal drawing treatment through a horizontal tube furnace, and then collected on another reel. A tube furnace with a length of 80cm is adopted, and three (secondary) hot drawing is adopted, wherein the first-stage drawing temperature is 210°C, and the drafting ratio is 3 times, and the second-stage drafting temperature is 240°C, and the drafting ratio is 2 times , The third stage drawing temperature is 260°C, and the drawing ratio is 1.5 times.

5) Put the hot-drawn polyether ketone ketone fiber together with the reel into a hot oven for high-temperature heat setting treatment. The heat setting temperature is 280 ° C, and the heat setting time is 2 hours to obtain heat-set polyether ketone ketone fiber.

The polyether ketone ketone fiber obtained through the above steps has a diameter of 160 μm, a mass density of 0.87 g/cm ³ (corresponding to a porosity of 33.1%), a tensile breaking strength of 605 MPa, a thermal weight loss temperature higher than 455 ° C, and a flame-retardant grade of V -Level 0.

Example 3

This embodiment provides a method for preparing polyether ketone ketone fibers based on a non-destructive dissolution wet method, which specifically includes:

1) Prepare a polyether ketone ketone solution, dissolve polyether ketone ketone (T/I is 50:50) in p-chlorophenol at a temperature of 50°C, the concentration is 8.5wt%, the stirring speed is 1200rpm, and the stirring time is 12h, to obtain Uniform and stable wet spinning dope.

2) Same operation as step 2) in Example 1, except that the coagulation bath is ethanol.

3)-5): Same as steps 3)-5) in Example 1.

The polyether ketone ketone fiber obtained through the above steps has a diameter of 38 μm, a mass density of 0.84 g/cm ³ (corresponding to a porosity of 35.4%), a tensile breaking strength of 675 MPa, a thermal weight loss temperature higher than 455 ° C, and a flame-retardant grade of V -Level 0.

Example 4

This embodiment provides a method for preparing polyether ketone ketone fibers based on a non-destructive dissolution wet method, which specifically includes:

1) Prepare a polyether ketone ketone solution, dissolve polyether ketone ketone (T/I ratio 70:30) in p-chlorophenol at 50°C, the concentration is 12wt%, the stirring speed is 1800rpm, and the stirring time is 9h to obtain a uniform, Stable wet spinning dope.

2) Same operation as step 2) in Example 1, except that the coagulation bath is ethanol.

3)-5): Same as steps 3)-5) in Example 1.

The polyether ketone ketone fiber obtained through the above steps has a diameter of 59 μm, a mass density of 0.86 g/cm ³ (corresponding to a porosity of 33.8%), a tensile breaking strength of 685 MPa, a thermal weight loss temperature higher than 455 ° C, and a flame-retardant grade of V -Level 0.

Comparative example 1

1) Prepare a polyether ketone ketone solution, dissolve polyether ketone ketone (T/I ratio 60:40) in trifluoroacetic acid at room temperature, the concentration is 4.5wt%, the stirring speed is 1200rpm, and the stirring time is 6h to obtain a uniform , Stable spinning dope.

2) When the operation is the same as step 2) in Example 1, continuous spinning cannot be formed, and segmented polyetherketoneketone short fibers are obtained.

Comparative example 2

1) Same operation as step 1) in Example 1.

2) The operation is the same as that of step 2) in Example 1, except that the extrusion rate is 3mL/min. Under high-speed injection, the polyether ketone ketone fibers curl up, making it difficult to draw stably, and continuous spinning cannot be formed.

The foregoing is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any form and in essence. Several improvements and supplements are made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims (6)

1. A method for preparing a polyetherketoneketone fiber based on non-destructive dissolution, which is characterized by comprising the following steps:

step 1: adopting fluorine-based or chlorine-based polar solvent to dissolve the polyether ketone in a nondestructive manner to obtain spinning solution;

step 2: carrying out wet spinning on the spinning solution obtained in the step 1, injecting the wet spinning solution into a coagulating bath for coagulating and forming, and pre-drafting, drying and winding to obtain a primary spinning polyether ketone fiber;

step 3: winding and collecting the as-spun polyether-ketone fiber obtained in the step 2 after multistage hot drawing, and performing heat treatment and shaping to obtain the polyether-ketone fiber;

in the polyetherketoneketone in the step 1, the molar ratio of the para-benzene position structure to the ortho-benzene position structure is 50:50, 60:40, 70:30, 80:20 or 100:0, and the polyetherketoneketone is powder with the particle size less than or equal to 300 mu m;

the fluorine base solvent in the step 1 is trifluoroacetic acid and/or 3, 3-trifluoro-2, 2-dimethylpropionic acid; the chlorine base polar solvent is at least one of p-chlorophenol, dichloroacetic acid and dichloropropionic acid;

the dissolved technological parameters in the step 1 are as follows: stirring speed is 1200-1800 rpm, stirring time is 6-12 h, and stirring temperature is 25-50 ℃; the concentration of the polyether ketone in the spinning solution is 5-22 wt%;

the wet spinning in the step 2 adopts a needle head with the inner diameter of 0.1-0.5 mm and the length of 50-100 mm; the technological parameters of the injection are as follows: the extrusion rate is 0.05-2 mL/min, and the extrusion temperature is 25-30 ℃;

the mass density of the polyether ketone fiber prepared in the step 3 is lower than 0.9g/cm ³ The porosity is higher than 30%, the tensile breaking strength is higher than 600MPa, the thermal weight loss temperature is higher than 450 ℃, and the flame retardant grade is V-0.

2. The method for preparing polyetherketoneketone fibers based on non-destructive dissolution according to claim 1, wherein the coagulation bath in step 2 is water or ethanol.

3. The method for preparing the polyetherketoneketone fiber based on non-destructive dissolution according to claim 1, wherein the temperature of the coagulation bath in the step 2 is 5 to 40 ℃, and the time required for the molding is 0.5 to 2min; the pre-drafting specifically comprises the following steps: and (3) guiding the polyether-ketone fibers obtained by solidification forming out of a solidification bath, drawing the fibers through 3-5 guide rails, wherein the drawing multiple is 1-2 times, and the drawing time is 1-5 min, so that the fibers are naturally dried, and winding and collecting the fibers after pre-drawing.

4. The method for preparing the polyetherketoneketone fiber based on nondestructive dissolution according to claim 1, wherein the hot drawing in the step 3 is that the as-spun polyetherketoneketone fiber obtained in the step 2 is hot drawn by a horizontal tube furnace, the length of the furnace body of the horizontal tube furnace is 50-90 cm, the hot drawing adopts three-stage hot drawing, and the specific technological parameters are as follows: the first stage drawing temperature is 200-220 ℃, the drawing multiple is 2-3.5 times, the second stage drawing temperature is 230-250 ℃, the drawing multiple is 1.5-2 times, the third stage drawing temperature is 240-260 ℃, and the drawing multiple is 1.5-2 times.

5. The method for preparing the polyetherketoneketone fiber based on non-destructive dissolution according to claim 1, wherein the heat treatment setting temperature in the step 3 is 240-300 ℃ for 1-5 hours.

6. The polyetherketoneketone fiber prepared by the process for preparing polyetherketoneketone fibers based on non-destructive dissolution according to any one of claims 1 to 5, wherein the polyetherketoneketone fiber has a mass density of less than 0.9g/cm ³ The porosity is higher than 30%, the tensile breaking strength is higher than 600MPa, the thermal weight loss temperature is higher than 450 ℃, and the flame retardant grade is V-0.

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