A method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent

Abstract

The invention relates to the technical field of high-performance composite materials, and discloses a method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high-boiling point coagulant and efficient solvent recovery. The preparation method of the invention comprises: using a fluorine-based and / or chlorine-based polar solvent to dissolve short carbon fiber and polyetherketoneketone, and obtaining a homogeneous mixed solution after stirring; pouring the mixed solution into a high-boiling point coagulant, stirring to fully solidify the short carbon fiber / polyetherketoneketone, and obtaining a short carbon fiber / polyetherketoneketone composite block and a fluorine-based and / or chlorine-based polar solvent / high-boiling point coagulant mixed solution; washing, drying, and grinding the composite block to obtain a short carbon fiber / polyetherketoneketone composite powder; fractionating the solvent / coagulant mixed solution to obtain a reusable fluorine-based and / or chlorine-based polar solvent and a high-boiling point coagulant. The material of the invention provides a rapid and complete phase separation means, an effective solvent recovery strategy, and a high-performance composite powder for industrial preparation of composite powder by a solution method.

Description

Technical Field

[0001] The invention relates to the technical field of high-performance composite materials, and in particular to a method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high-boiling point coagulant and efficient recovery of a solvent. Background Art

[0002] With the rapid development of high-performance composite materials, the application of high-temperature resistant and high-strength composite materials in aerospace, atomic energy engineering, automotive parts, electronic appliances, and medical devices is increasing. In the application scenarios of structural parts, bearings, artificial bones, etc., injection molding and 3D printing are two important molding methods, and their main raw materials are powders and granules. For high-polarity and high-melt viscosity high-performance polymers such as polyetherketoneketone (PEKK) and polyphenylene sulfide (PPS), the current processing methods of composite powders mainly include mechanical blending / melt compounding, solution compounding, and in-situ compounding. Among them, the solution compounding method greatly reduces the viscosity of the mixture system, can achieve more sufficient pre-compounding, effectively avoids multiple high-temperature damage, simplifies the process to make it easier to industrially scale up, and is conducive to increasing the load of the reinforcement body. It has become an important means of composite powder processing. However, although the wet compounding process is simple and the compounding effect is good, it is difficult to completely remove the solvent by phase separation and the solvent recovery process is relatively complicated. How to achieve phase separation and achieve efficient recovery of the used solvent is an important issue for further improving the solution compounding process.

[0003] In addition to powder, the processing of other PEKK materials also involves solvent removal and recovery issues, such as: 1) Chinese invention patent ZL202111055042.1 uses a direct heating method to remove solvents to obtain carbon fiber / PEKK prepreg bundles; 2) Chinese invention patent ZL202210401927.0 uses ultrapure water, anhydrous ethanol and other low melting point solvents as coagulants to achieve phase separation, and obtains carbon fiber / PEKK composite membranes, which are then dried, ground and sieved to obtain composite powders; 3) Chinese invention patent application 202311709281.3 selects glacial acetic acid / glacial ultrapure water as coagulants, and vacuum filtration is performed to obtain the initial The first step is to achieve phase separation, and then obtain carbon nanotube / polyaryletherketone composite dry material after washing and drying; 4) Chinese invention patent applications 202310087414.1, 202310442837.0, and 202311395330.0 achieve complete phase separation of the PEKK membrane obtained by electrospinning / extrusion in anhydrous ethanol, deionized water or a mixed solution thereof to obtain a membrane material that can be used as cable insulation; and 5) Chinese invention patent application 202411255732.5 uses water or caustic soda solution as the first coagulation bath and ethanol, ether or acetone as the second coagulation bath for wet spinning to obtain high-strength PEKK fiber. The above processes are all removed by direct drying or soaking in a low-boiling point coagulant, which will produce a large amount of waste gas and waste liquid, causing environmental pollution, and the solvent and coagulant cannot be recycled and reused, the production cost is high, and it is difficult to truly apply it in industrial production.

[0004] Extraction-washing-drying is a commonly used phase separation method in chemical reactions, which can be introduced into the phase separation process of composite powders. On the one hand, extraction can be used to effectively remove the solvent, and on the other hand, the liquid after extraction can be fractionated to recover the solvent and coagulant for reuse, thereby reducing costs and reducing waste discharge. However, PEKK solution usually uses trifluoroacetic acid as a solvent, and the currently selected coagulants (ultrapure water, anhydrous ethanol, etc.) bring about a relatively slow extraction speed (usually by lowering the coagulant temperature to accelerate the extraction), and the boiling points of the two are close. During the extraction fractionation recovery process, the low-melting point coagulant will still mix with the volatile solvent, resulting in the recovery of The solvent cannot be reused.

[0005] Therefore, finding a suitable phase separation coagulant and further realizing the separation and recovery of solvent / coagulant are the keys to the large-scale application of solution-processed high-performance composite powders. Taking into account the two processes of phase separation and solvent recovery, a PEKK composite powder preparation method based on rapid phase separation of high-boiling point coagulants and efficient solvent recovery came into being: the significant difference in coagulant solubility and boiling point between PEKK and trifluoroacetic acid is used to achieve sufficient and rapid phase separation, and the significant difference in boiling point between trifluoroacetic acid solvent and coagulant is used to achieve reagent fractionation and recovery. This strategy can not only achieve efficient phase separation and reagent recovery and reuse, but also significantly reduce industrial costs and pollution caused by waste gas and waste liquid. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the shortcomings of the prior art, the present invention provides a method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high-boiling point coagulant and efficient recovery of a solvent, which solves the problems of incomplete phase separation and low efficiency in the existing solution method for preparing composite materials, and the increased cost and large discharge volume caused by the inability to separate the solution after extraction.

[0008] (II) Technical solution

[0009] The present invention provides a method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high-boiling point coagulant and efficient recovery of a solvent, comprising the following steps:

[0010] Step 1: Disperse / dissolve the chopped carbon fiber and polyetherketoneketone in a fluorine-based and / or chlorine-based polar solvent in a certain mass ratio, and stir thoroughly to obtain a uniformly dispersed chopped carbon fiber / polyetherketoneketone mixed solution;

[0011] Step 2: pouring the chopped carbon fiber / polyetherketoneketone mixed solution into the high boiling point coagulant and stirring to obtain a chopped carbon fiber / polyetherketoneketone composite block and a mixed solution of a fluorine-based and / or chlorine-based polar solvent and a high boiling point coagulant;

[0012] Step 3: washing, drying and grinding the chopped carbon fiber / polyetherketoneketone composite block to obtain chopped carbon fiber / polyetherketoneketone composite powder;

[0013] Step 4: fractionate the mixed solution of the fluorine-based and / or chlorine-based polar solvent and the high-boiling point coagulant to separate the two, so as to prepare for the subsequent solution preparation and the reuse of the mixed solution phase separation process.

[0014] Preferably, the chopped carbon fiber in step 1 is asphalt-based or polyacrylonitrile-based carbon fiber with a length of 1 to 5 mm; in the polyetherketoneketone, the molar ratio of the para-phenylene structure to the ortho-phenylene structure (referred to as the para-to-ortho structure ratio, or T / I ratio) is 50:50, 60:40, 70:30, 80:20 or 100:0, and the polyetherketoneketone is a powder with a particle size of ≤300 μm.

[0015] Preferably, the fluorine-based and / or chlorine-based polar solvent in step 1 is trifluoroacetic acid, 3,3,3-trifluoro-2,2-dimethylpropionic acid, chlorosulfonic acid, p-chlorophenol, dichloroethane, dichloroacetic acid and dichloropropionic acid.

[0016] More preferably, the fluorine-based and / or chlorine-based polar solvent is trifluoroacetic acid.

[0017] Preferably, in step 1, the mass ratio of the chopped carbon fiber to the polyetherketoneketone is 1:5-20, and the concentration of the chopped carbon fiber / polyetherketoneketone mixture is 5-12wt%.

[0018] Preferably, the dissolution process conditions in step 1 are: stirring at 25-50° C. and 1200-1800 rpm for 6-24 hours.

[0019] Preferably, the high boiling point coagulant in step 2 is ethylene glycol, propylene glycol, butanetriol, hexanol, or heptanol.

[0020] More preferably, the high boiling point coagulant is ethylene glycol.

[0021] Preferably, in step 2, the mass ratio of the mixed liquid to the coagulant is 1:1-5, and the stirring method is stirring with a handheld glass rod or stirring with a motor stirring paddle.

[0022] Preferably, the process parameters of the drying treatment in step 3 are: temperature 100-150°C, time 0.5-2h; the process parameters of the grinding are: crusher speed 20000rpm, the distance between the crusher blade and the bottom of the machine is 1cm, crushing temperature 25-50°C, and crushing time 5-25min.

[0023] Preferably, the process parameters of the fractionation treatment in step 4 are: fractionation temperature 50-150° C., fractionation stop mark: no droplets in the tail pipe.

[0024] (III) Beneficial technical effects

[0025] (1) The present invention is based on the fact that polyetherketoneketone is soluble in fluorine-containing or chlorine-containing polar solvents to realize wet preparation of polyetherketoneketone composite powder, and innovatively uses high-boiling point alcohol reagents to achieve two-phase separation of chopped carbon fiber / polyetherketoneketone and trifluoroacetic acid. Its technical route is to first prepare a mixed solution of chopped carbon fiber / polyetherketoneketone, and use the difference in solubility of chopped carbon fiber / polyetherketoneketone and trifluoroacetic acid in ethylene glycol to fully stir and completely dissolve trifluoroacetic acid in ethylene glycol. Different from traditional solvent removal processes such as direct distillation and adsorption drying, chopped carbon fiber / polyetherketoneketone composite blocks can be obtained efficiently and completely, thereby obtaining fully pre-compounded composite powder.

[0026] (2) The present invention uses a high-boiling-point alcohol solvent as a coagulant, which effectively avoids the mixing of other reagents into the trifluoroacetic acid recovered by fractionation and has an adverse effect on subsequent use. In addition, the present invention can achieve separation of the solvent and the coagulant at a relatively low temperature, and by recycling and reusing the solvent and the coagulant, the solvent cost in the solution method for preparing the composite material is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The mixed solution obtained in step 1 of Example 1.

[0028] Figure 2 It is the composite block obtained in step 2 of Example 1.

[0029] Figure 3 The chopped carbon fiber / polyetherketoneketone composite powder obtained in step 3 of Example 1.

[0030] Figure 4 This is the thermal gravimetric test result of the chopped carbon fiber / polyetherketoneketone composite powder obtained in Example 1 in an air environment. DETAILED DESCRIPTION

[0031] In order to make the present invention more clearly understood, a preferred embodiment is described in detail with reference to the accompanying drawings as follows:

[0032] like Figure 1-4 As shown, the present invention provides a method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high-boiling point coagulant and efficient recovery of a solvent.

[0033] Example 1

[0034] This embodiment provides a method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high boiling point coagulant and efficient recovery of a solvent, which specifically comprises the following steps:

[0035] Step 1: Disperse / dissolve 3 g of polyacrylonitrile-based chopped carbon fiber (3 mm) and 21 g of polyetherketoneketone in 176 g of trifluoroacetic acid, and stir at 1500 rpm for 15 h to obtain a uniformly dispersed chopped carbon fiber / polyetherketoneketone mixed solution, such as Figure 1 As shown;

[0036] Step 2: Pour the chopped carbon fiber / polyetherketoneketone mixture in step 1 into 600g of ethylene glycol, and stir with a glass rod until the chopped carbon fiber / polyetherketoneketone is completely solidified to obtain a chopped carbon fiber / polyetherketoneketone composite block ( Figure 2 ) and a trifluoroacetic acid / ethylene glycol mixture;

[0037] Step 3: Wash the chopped carbon fiber / polyetherketoneketone composite block obtained in step 2 and dry it in an oven at 100°C for 2h. Grind the dried composite material in a grinder at 20000rpm and 40°C for 10min to obtain chopped carbon fiber / polyetherketoneketone composite powder. Figure 3 , where the distance between the pulverizer blade and the bottom of the machine is set to 1 cm;

[0038] Step 4: The trifluoroacetic acid / ethylene glycol mixed solution obtained in step 2 is fractionally distilled at 70° C. until there are no droplets in the tail pipe, thereby achieving separation of the two, and finally obtaining trifluoroacetic acid that can be used for subsequent solution preparation and ethylene glycol that can be repeatedly used for mixed liquid phase separation.

[0039] Example 2

[0040] This embodiment provides a method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high boiling point coagulant and efficient recovery of a solvent, which specifically comprises the following steps:

[0041] Step 1: 2.4 g of polyacrylonitrile-based chopped carbon fibers (1 mm) and 21.6 g of polyetherketoneketone were dispersed / dissolved in 176 g of trifluoroacetic acid, and stirred at 1800 rpm for 12 h to obtain a uniformly dispersed chopped carbon fiber / polyetherketoneketone mixture;

[0042] Step 2: pour the chopped carbon fiber / polyetherketoneketone mixed solution in step 1 into 1000 g of heptanol, and stir with an electric stirring paddle until the chopped carbon fiber / polyetherketoneketone is completely solidified to obtain a chopped carbon fiber / polyetherketoneketone composite block and a trifluoroacetic acid / heptanol mixed solution;

[0043] Step 3: Wash the chopped carbon fiber / polyetherketoneketone composite block obtained in step 2 and dry it in an oven at 150° C. for 1 h, and grind the dried composite material in a grinder at 20,000 rpm and 25° C. for 30 min to obtain chopped carbon fiber / polyetherketoneketone composite powder, wherein the distance between the grinder blade and the bottom of the grinder is set to 1 cm;

[0044] Step 4: The trifluoroacetic acid / heptanol mixed solution obtained in step 2 is fractionally distilled at 90° C. until there are no droplets in the tail pipe, thereby achieving separation of the two for subsequent solution preparation and reuse in the mixed liquid phase separation process.

[0045] Performance test: The chopped carbon fiber / polyetherketoneketone composite powder obtained in Examples 1-2 was subjected to a thermal gravimetric test. The thermal stability of the composite powder was tested using a thermogravimetric analyzer. The specific procedure was: heating the temperature to 1000°C at a heating rate of 10°C / min in an air atmosphere. The results showed that the thermal gravimetric temperatures of the chopped carbon fiber / polyetherketoneketone composite powders obtained in Examples 1-2 were all around 550°C. The thermal gravimetric curve of the chopped carbon fiber / polyetherketoneketone composite powder obtained in Example 1 is shown in FIG. Figure 4 .

[0046] Comparative Example 1

[0047] Step 1: 3 g of polyacrylonitrile-based chopped carbon fiber (3 mm) and 21 g of polyetherketoneketone were dispersed / dissolved in 176 g of trifluoroacetic acid, and stirred at 20,000 rpm for 12 h to obtain a uniformly dispersed chopped carbon fiber / polyetherketoneketone mixed solution;

[0048] Step 2: Heat the chopped carbon fiber / polyetherketoneketone mixture in step 1 in a water bath, and perform solid-liquid phase separation and trifluoroacetic acid recovery by direct distillation. The resulting chopped carbon fiber / polyetherketoneketone composite block is heated unevenly, resulting in extremely hard blocks and areas that have not been completely phase-separated, which affects the subsequent powder preparation. In addition, due to the high concentration of the configured chopped carbon fiber / polyetherketoneketone mixture, the distillation speed is slow and the efficiency is low.

[0049] Comparative Example 2

[0050] Step 1: 3 g of polyacrylonitrile-based chopped carbon fiber (3 mm) and 21 g of polyetherketoneketone were dispersed / dissolved in 176 g of trifluoroacetic acid, and stirred at 20,000 rpm for 12 h to obtain a uniformly dispersed chopped carbon fiber / polyetherketoneketone mixed solution;

[0051] Step 2: Pour the chopped carbon fiber / polyetherketoneketone mixed liquid in step 1 into ethanol. The surface of the obtained chopped carbon fiber / polyetherketoneketone composite block is solidified, while the interior is still the chopped carbon fiber / polyetherketoneketone composite liquid. It must be broken apart one by one to achieve phase separation in ethanol, which is inefficient and has the defect of incomplete phase separation.

[0052] Step 3: washing, drying and grinding the chopped carbon fiber / polyetherketoneketone composite block to obtain chopped carbon fiber / polyetherketoneketone composite powder;

[0053] Step 4: fractionating the mixture of trifluoroacetic acid and ethanol, it is impossible to separate the two. Since the boiling points of the two are similar, the distilled product is still a mixed solution and cannot be reused.

[0054] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a polyetherketoneketone composite powder based on rapid phase separation of a high boiling point coagulant and efficient recovery of a solvent, characterized in that: The following steps are involved: Step 1: Disperse / dissolve chopped carbon fiber and polyetherketoneketone in a fluorine-based and / or chlorine-based polar solvent in a certain mass ratio, and stir thoroughly to obtain a uniformly dispersed chopped carbon fiber / polyetherketoneketone mixed solution; wherein the chopped carbon fiber is polyacrylonitrile-based or asphalt-based, and has a length of 1 to 5 mm; the molar ratio of the para-phenylene structure to the ortho-phenylene structure in the polyetherketoneketone is 50:50, 60:40, 70:30, 80:20 or 100:0, and a powder with a particle size of ≤300 μm is selected; Step 2: pouring the chopped carbon fiber / polyetherketoneketone mixed solution into the high-boiling point coagulant and stirring to obtain the chopped carbon fiber / polyetherketoneketone composite block and the mixed solution of the fluorine-based and / or chlorine-based polar solvent and the high-boiling point coagulant; wherein the stirring method is stirring with a handheld glass rod or stirring with a motor stirring paddle; Step 3: washing, drying and grinding the chopped carbon fiber / polyetherketoneketone composite block to obtain chopped carbon fiber / polyetherketoneketone composite powder; Step 4: fractionate the mixed solution of the fluorine-based and / or chlorine-based polar solvent and the high-boiling point coagulant to separate the two, so as to prepare for the subsequent solution preparation and the reuse of the mixed solution phase separation process.

2. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent as claimed in claim 1, characterized in that: The fluorine-based and / or chlorine-based polar solvent in step 1 is trifluoroacetic acid, 3,3,3-trifluoro-2,2-dimethylpropionic acid, chlorosulfonic acid, p-chlorophenol, dichloroethane, dichloroacetic acid and dichloropropionic acid.

3. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent as claimed in claim 1, characterized in that: In the step 1, the mass ratio of the chopped carbon fiber to the polyetherketoneketone is 1:5-20, and the concentration of the chopped carbon fiber / polyetherketoneketone mixture is 5-12wt%.

4. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent as described in claim 1, characterized in that: The dissolution process conditions in step 1 are: stirring at 25-50° C. and 1200-1800 rpm for 6-24 hours.

5. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient solvent recovery as described in claim 1, characterized in that: In step 2, the high boiling point coagulant is ethylene glycol, propylene glycol, butanetriol, hexanol, and heptanol; and the mass ratio of the mixed solution to the coagulant is 1:1-5.

6. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent as described in claim 1, characterized in that: The process parameters of the drying treatment in step 3 are: temperature 100-150° C., time 0.5-2 h.

7. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent as described in claim 1, characterized in that: The grinding process parameters in step 3 are: a grinding machine speed of 20,000 rpm, a distance of 1 cm between the grinding machine blade and the bottom of the machine, a grinding temperature of 25-50° C., and a grinding time of 5-25 min.

8. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent as described in claim 1, characterized in that: The process parameters of the fractionation treatment in step 4 are: fractionation temperature 50-150°C.

9. The method for preparing polyetherketoneketone composite powder based on rapid phase separation of high boiling point coagulant and efficient recovery of solvent as described in claim 1, characterized in that: The mark for stopping fractionation in step 4 is: no droplets in the tail pipe.

10. The chopped carbon fiber / polyetherketoneketone composite powder obtained by the preparation method based on rapid phase separation of a high boiling point coagulant and efficient recovery of a solvent as described in any one of claims 1 to 9.

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