Chopped carbon fiber reinforced polyphenylene sulfide pre-composite powder and preparation method thereof

Abstract

The invention discloses chopped carbon fiber reinforced polyphenylene sulfide pre-composite powder and a preparation method thereof. The preparation method comprises the following steps: adding the chopped carbon fibers into a homogeneous polyphenylene sulfide solution for dispersion, and obtaining a uniformly dispersed chopped carbon fiber / polyphenylene sulfide mixed solution by convection; adding a coagulating agent to separate the chopped carbon fiber / polyphenylene sulfide from the solvent, further washing off the solvent by using a suction filtration device, and finally drying in a vacuum oven to obtain chopped carbon fiber / polyphenylene sulfide composite powder; and crushing and sieving the chopped carbon fiber / polyphenylene sulfide composite powder to obtain the chopped carbon fiber / polyphenylene sulfide composite powder. According to the method, a high-pressure convection solvent thermal compounding process is adopted, the solubility of polyphenylene sulfide can be improved, the steps of dissolving, diffusing, infiltrating and the like are fused into a dynamic continuous process, and uniform dispersion of the carbon fibers and efficient and rapid compounding of the carbon fibers and polyphenylene sulfide are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of carbon fiber reinforced polyphenylene sulfide pre-composite powder and its preparation method, belong to polymer composite field. BACKGROUND

[0002] Driven by the growing demand in high-end application fields such as automotive, aerospace, medical, energy, the market of high temperature resistant special engineering resin is continuously rising. Compared with traditional thermoplastic resins, polyaryletherketone (PAEK), polyphenylene sulfide (PPS), polyimide (PI) and polysulfone (PSF) have become the key choice to meet these harsh applications due to their excellent high temperature stability and mechanical properties. Among them, PPS is known for its excellent thermal stability, with a melting point of about 285℃, and can be used at temperatures below 220℃ for a long time. In addition, PPS also has high mechanical strength, strong chemical corrosion resistance, excellent electrical insulation and flame retardance. Despite the many advantages of PPS, it also has obvious limitations, mainly manifested in brittle texture, insufficient toughness and weak impact resistance. These shortcomings in mechanical properties restrict the wide application of pure PPS resin, in order to effectively improve the mechanical properties, carbon fiber, with excellent heat resistance, high strength and rigidity, has become a commonly used and effective material to reinforce pure PPS resin. For example: literature Chukov D, Nematulloev S, Zadorozhnyy M, et al., Structure, Mechanical and Thermal Properties of Polyphenylene Sulfide and Polysulfone Impregnated Carbon Fiber Composites, Polymers 2019, 11(4), 684, after chemical treatment of carbon fiber and polyphenylene sulfide powder hot pressing, its tensile strength and modulus are greatly improved.

[0003] At present, the main composite method of carbon fiber reinforced polyphenylene sulfide is melt processing, for example, Chinese invention patent application 202411049878.4 first dips the carbon fiber in the molten polyphenylene sulfide resin, then performs layering and laying, and forms a laminated board after hot pressing; Chinese invention patent application 202111368686.6 puts short carbon fiber and polyphenylene sulfide, polytetrafluoroethylene and other materials into a double screw extruder for melt mixing and extrusion; in Chinese invention patent application 202411616441.4, carbon fiber is blended with polyphenylene sulfide and other materials, and carbon fiber reinforced PPS composite material is prepared by extrusion granulation, and then CF-PPS wire is prepared by melt spinning; the authorized Chinese invention patent ZL201710239469.4 blends short carbon fiber, PPS and processing aids, and then uses melt resin impregnation composite process to prepare PPS composite material granules. Although these melt processing methods can improve the strength of the material, the high melt temperature, high viscosity and strong surface tension of the resin make it difficult to ensure that the fiber and the resin form a fully combined interface, and it is also difficult to effectively prevent the agglomeration of carbon fiber in the matrix. Moreover, the surface modification of carbon fiber or the addition of other additives increases the processing complexity and cost. In fact, the problems encountered by PPS are common in many high-performance thermoplastic resins, such as polyether ketone ketone (PEKK) and polyether ether ketone (PEEK).

[0004] To this end, the solution method has become a new means to solve the problems of melt processing by achieving full compounding of the reinforcing body and the resin. For example, the authorized Chinese invention patent ZL202210401927.0 successfully realized the uniform and sufficient coating of PEKK resin on the surface of carbon fiber based on the breakthrough of its room temperature dissolution technology, effectively overcoming the problem of insufficient wetting in melt processing. The interfacial bonding strength and overall mechanical properties of the composite material prepared by this process and hot pressing are significantly improved. The successful practice of this method provides an important reference for the development of PPS composite system. However, PPS is almost insoluble at room temperature and can only be dissolved in some organic solvents at high temperature, such as NMP (N-methyl pyrrolidone) and 1-chloronaphthalene. However, even under high temperature conditions, the solubility of PPS is still limited. How to achieve efficient compounding of carbon fiber with PPS at low concentration has become a key challenge. SUMMARY

[0005] The problem to be solved by the present application is that the related process for preparing short carbon fiber / polyphenylene sulfide composite powder by solution method is difficult and costly at present, and it is difficult to achieve uniform coating of short carbon fiber and polyphenylene sulfide by using existing melt processing or mechanical mixing methods.

[0006] In order to solve the above problems, the application provides a high-pressure convection solvent thermal compounding process mode for manufacturing pre-compounded powder, realizing efficient and uniform pre-compounding of CF and PPS, and obtaining a mechanical performance excellent product through hot-pressing.

[0007] The technical scheme provided by the application to solve the above problems is as follows: A preparation method of short-cut carbon fiber reinforced polyphenylene sulfide pre-compounded powder, comprising the following steps: Step 1): dissolving polyphenylene sulfide by using an organic solvent to obtain a homogeneous polyphenylene sulfide solution; Step 2): adding short-cut carbon fibers into the homogeneous polyphenylene sulfide solution and dispersing, and obtaining a uniformly dispersed short-cut carbon fiber / polyphenylene sulfide mixed solution by using convection; Step 3): adding a coagulant into the short-cut carbon fiber / polyphenylene sulfide mixed solution to separate the short-cut carbon fiber / polyphenylene sulfide from the solvent, further washing the solvent by using a suction filtration device, and finally drying in a vacuum oven to obtain a short-cut carbon fiber / polyphenylene sulfide compounded powder; Step 4): crushing and sieving the short-cut carbon fiber / polyphenylene sulfide compounded powder to obtain a short-cut carbon fiber / polyphenylene sulfide compounded powder.

[0008] Preferably, in the step 1), the polyphenylene sulfide is selected from a granular material with a molecular weight of 20000-30000, and the organic solvent is NMP.

[0009] Preferably, in the step 1), the dissolving process conditions are as follows: in a closed container, the temperature is 200-220℃, the pressure is 1.1-1.3 MPa, and the dissolving time is 3-6 h; and the concentration of the obtained polyphenylene sulfide solution is 4-8 wt%.

[0010] Preferably, in the step 2), the short-cut carbon fibers are micron-level short-cut carbon fibers with a length of 1-3 mm; the mass ratio of the carbon fibers to the polyphenylene sulfide in the short-cut carbon fiber / polyphenylene sulfide mixed solution is 1:5-15; and the dispersion process conditions are as follows: 200-220℃, the pressure is 1.1-1.3 MPa, and the convection compounding time is 6-8 h.

[0011] Preferably, in the step 3), the coagulant is anhydrous ethanol and ultrapure water; and the drying process parameters are as follows: the first-stage drying temperature is 80-150℃, the high-vacuum state is maintained for 4-8 h, the second-stage drying temperature is 120-170℃, and the high-vacuum state is maintained for 2-4 h.

[0012] Preferably, in the step 4), the crushing process parameters are as follows: the speed of the crusher is 15000 rpm, the distance between the blades of the crusher and the bottom of the crusher is 0.75 cm, the crushing temperature is 20-50℃, and the crushing time is 10-20 min; and the mesh size of the sieve is 50 mesh.

[0013] The application further provides the short carbon fiber reinforced polyphenylene sulfide composite powder prepared by the preparation method.

[0014] The application further provides application of the short carbon fiber reinforced polyphenylene sulfide pre-composite powder, characterized in that the short carbon fiber reinforced polyphenylene sulfide pre-composite powder is placed in a mold, and a short carbon fiber / polyphenylene sulfide composite material is obtained through hot pressing.

[0015] Preferably, the process parameters of the hot pressing are as follows: a pressure of 2-15 MPa, a preheating temperature of 310-370 DEG C, a preheating time of 30-60 min, a pressure maintaining temperature of 310-370 DEG C, and a pressure maintaining time of 10-50 min.

[0016] The application realizes continuous dissolution and precipitation of PPS in NMP under limited dissolution conditions at a temperature close to the boiling point, and promotes continuous dissolution of PPS and rapid migration of PPS to the surface of carbon fibers under the action of convective mass transfer, so that the new carbon fiber pre-composite PPS powder is developed, and the technical bottleneck that the existing PEKK wet pre-composite is difficult to be applied to PPS is solved.

[0017] Compared with the prior art, the application has the following beneficial effects: 1、The application designs a "boiling point dissolution-convective compounding" wet processing system, and improves the compounding efficiency and quality. By controlling the reaction system in a high-pressure environment near the boiling point of NMP solvent, the boiling effect and the convective effect are creatively utilized, the solid-liquid interface is continuously updated, the dissolution kinetics process of PPS is greatly promoted, and the steps of dissolution, diffusion and infiltration are integrated into a dynamic continuous process, so that the uniform dispersion of carbon fibers and the efficient and rapid compounding of polyphenylene sulfide are realized, and the key bottleneck of low compounding efficiency of high-performance thermoplastic resin in the conventional wet process is overcome. In addition, a specific sealed reaction system is used to balance the temperature and pressure, so that the high-temperature volatilization of NMP solvent is effectively inhibited, and the system pressure is maintained in a safe and controllable range.

[0018] 2, The present application successfully develops a kind of carbon fiber reinforced polyphenylene sulfide pre-composite powder, the powder has the following obvious advantages: first, by optimizing composite process, higher carbon fiber load and more uniform dispersion state are realized, the problem of insufficient fiber and resin infiltration in traditional melt processing is solved, so that the composite material makes significant breakthrough in key mechanical properties such as strength.In addition, the powder has good processing adaptability, not only suitable for traditional hot pressing forming, but also expected to be applied in 3D printing and injection molding, and has good industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The preparation method provided by the present application is shown in the process flow chart; Figure 2 The actual picture of CF / PPS pre-composite powder prepared in Example 1 is shown in the figure; Figure 3 The scanning electron microscope picture of CF / PPS pre-composite powder prepared in Example 1 is shown in the figure; Figure 4 The actual picture of CF / PPS composite material prepared in Example 1 is shown in the figure; Figure 5 The scanning electron microscope picture of CF / PPS composite material tensile fracture section prepared in Example 1 is shown in the figure; Figure 6 The tensile curve mechanics diagram of CF / PPS composite material prepared in Example 1 is shown in the figure; Figure 7 The scanning electron microscope picture of CF / PPS pre-composite powder prepared in Comparative Example 2 is shown in the figure. DETAILED DESCRIPTION

[0020] In order to make the present application more obvious and easy to understand, the preferred embodiment is described in detail as follows, and the accompanying drawings are shown.

[0021] Example 1 A preparation method of chopped carbon fiber / polyphenylene sulfide composite material, comprising the following steps: Step 1: polyphenylene sulfide (particle size ≤100 μm) is dissolved in NMP at 220 ℃, 1.2 MPa, the concentration is 6wt%, the dissolution time is 6h, and the homogeneous polyphenylene sulfide solution is obtained; Step 2: according to the mass ratio of chopped carbon fiber to polyphenylene sulfide of 1:7, length 1mm chopped carbon fiber is added to the homogeneous polyphenylene sulfide solution, and the mixed solution of uniformly dispersed chopped carbon fiber / polyphenylene sulfide is obtained under the conditions of 220 ℃, 1.2 MPa and 8h of convection composite; Step 3: Add anhydrous ethanol to the chopped carbon fiber / polyphenylene sulfide mixture to precipitate the chopped carbon fiber / polyphenylene sulfide, and then further extract and filter to obtain a composite powder, which is placed in a vacuum oven and dried at 100°C for 5h and at 170°C for 4h.

[0022] Step 4: The dried chopped carbon fiber / polyphenylene sulfide pre-composite powder is crushed, the speed of the crusher is set to 15000rpm, the distance between the blades of the crusher and the bottom of the machine is set to 0.75cm, the crushing temperature is 30°C, and the crushing time is 10min, and then the powder is sieved through a 50 mesh sieve to obtain a chopped carbon fiber / polyphenylene sulfide composite powder, as shown in Figure 2 The scanning electron microscope (SEM) results are shown in Figure 3 It can be seen that the surface of the carbon fiber is uniformly coated with polyphenylene sulfide resin.

[0023] Step 5: 1g of the chopped carbon fiber / polyphenylene sulfide composite powder is weighed and placed in a mold, the mold is preheated at 0.5MPa and 330°C for 40min, and then pressure is maintained at 8MPa and 330°C for 50min to obtain a chopped carbon fiber / polyphenylene sulfide composite material, as shown in Figure 4

[0024] Example 2 A method for preparing a chopped carbon fiber / polyphenylene sulfide composite material, comprising the following steps: Step 1: Dissolve polyphenylene sulfide (particle size ≤100μm) in NMP at 210°C and 1.1MPa, with a concentration of 4wt%, for 4h to obtain a homogeneous polyphenylene sulfide solution; Step 2: Add chopped carbon fibers with a length of 3mm to the homogeneous polyphenylene sulfide solution at a mass ratio of 1:9, and then conduct convective compounding at 210°C and 1.1MPa for 8h to obtain a uniformly dispersed chopped carbon fiber / polyphenylene sulfide mixture; Step 3: Add anhydrous ethanol to the chopped carbon fiber / polyphenylene sulfide mixture to precipitate the chopped carbon fiber / polyphenylene sulfide, and then further extract and filter to obtain a composite powder, which is placed in a vacuum oven and dried at 110°C for 5h and at 170°C for 4h.

[0025] Step 4: The dried chopped carbon fiber / polyphenylene sulfide pre-composite powder is crushed, the speed of the crusher is set to 15000rpm, the distance between the blades of the crusher and the bottom of the machine is set to 0.75cm, the crushing temperature is 30°C, and the crushing time is 10min, and then the powder is sieved through a 50 mesh sieve to obtain a chopped carbon fiber / polyphenylene sulfide composite powder.

[0026] ​Step 5: 1 g of the short carbon fiber / polyphenylene sulfide composite powder was weighed into a mold, the mold was preheated at 0.5 MPa and 310 ℃ for 60 min, and then was kept at 8 MPa and 310 ℃ for 70 min, to obtain the short carbon fiber / polyphenylene sulfide composite material.

[0027] Comparative Example 1 An attempt was made to prepare a short carbon fiber / polyphenylene sulfide composite solution: Step 1: The polyphenylene sulfide (particle size ≤ 100 μm) was dissolved in NMP at 210 ℃ and 1.1 MPa, with a concentration of 4 wt%, for 4 h, to obtain a homogeneous polyphenylene sulfide solution; Step 2: The short carbon fiber with a length of 3 mm was added to the homogeneous polyphenylene sulfide solution at a mass ratio of 1:3, and was subjected to flow compounding at 210 ℃ and 1.1 MPa for 8 h. The short carbon fiber was difficult to disperse in the solution, and a uniform short carbon fiber / polyphenylene sulfide composite solution could not be obtained.

[0028] Comparative Example 2 A method for preparing a short carbon fiber / polyphenylene sulfide composite powder: Step 1: The polyphenylene sulfide (particle size ≤ 100 μm) was dissolved in NMP at 210 ℃, with a concentration of 6 wt%, for 6 h, to obtain a homogeneous polyphenylene sulfide solution; Step 2: The short carbon fiber with a length of 1 mm was added to the homogeneous polyphenylene sulfide solution at a mass ratio of 1:7, and was subjected to compounding at 210 ℃ and 1400 rpm for 8 h, to obtain a uniformly dispersed short carbon fiber / polyphenylene sulfide mixture; Steps 3-5: Same as 3-5 in Example 1.

[0029] The short carbon fiber / polyphenylene sulfide composite powder prepared through the above steps was characterized by a scanning electron microscope, and it was found that the carbon fiber was not fully and uniformly coated with the polyphenylene sulfide resin, and the particle size of the polyphenylene sulfide resin was large and was not completely dissolved, as shown in Figure 6 .

[0030] Performance Test: The short carbon fiber / polyphenylene sulfide composite powder obtained in Example 1-2 and Comparative Example 2 was subjected to a powder performance test, and the short carbon fiber / polyphenylene sulfide composite material obtained in Example 1-2 and Comparative Example 2 was subjected to a mechanical property test, and the results are shown in Table 1. As can be seen from the results in Table 1, the obtained short carbon fiber / polyphenylene sulfide composite sheet has excellent tensile mechanical properties.

[0031] Table 1

Claims

1. A method for preparing a pre-composite powder of short-cut carbon fiber reinforced polyphenylene sulfide, characterized in that, Includes the following steps: Step 1): Dissolve polyphenylene sulfide in an organic solvent to obtain a homogeneous polyphenylene sulfide solution; Step 2): Short-cut carbon fibers are added to the homogeneous polyphenylene sulfide solution for dispersion, and a uniformly dispersed short-cut carbon fiber / polyphenylene sulfide mixture is obtained by convection. Step 3): Add a coagulant to the short-cut carbon fiber / polyphenylene sulfide mixture to separate the short-cut carbon fiber / polyphenylene sulfide from the solvent. Then, use a vacuum filter to further wash away the solvent. Finally, dry it in a vacuum oven to obtain short-cut carbon fiber / polyphenylene sulfide composite powder. Step 4): Crush and sieve the chopped carbon fiber / polyphenylene sulfide composite powder to obtain chopped carbon fiber / polyphenylene sulfide composite powder.

2. The method for preparing short-cut carbon fiber reinforced polyphenylene sulfide precomposite powder as described in claim 1, characterized in that, In step 1), the polyphenylene sulfide is selected from granules with a molecular weight of 20,000 to 30,000, and the organic solvent is NMP.

3. The method for preparing the short-cut carbon fiber reinforced polyphenylene sulfide precomposite powder as described in claim 1, characterized in that, In step 1), the dissolution process conditions are: in a closed container, temperature 200~220℃, pressure 1.1~1.3MPa, dissolution time 3~6h; the concentration of the resulting polyphenylene sulfide solution is 4~8wt%.

4. The method for preparing the short-cut carbon fiber reinforced polyphenylene sulfide precomposite powder as described in claim 1, characterized in that, In step 2), the chopped carbon fibers are micron-sized chopped carbon fibers with a length of 1-3 mm; the mass ratio of carbon fibers to polyphenylene sulfide in the chopped carbon fiber / polyphenylene sulfide mixture is 1:5-15; the dispersion process conditions are: 200-220℃, pressure 1.1-1.3MPa, and convection compounding for 6-8 hours.

5. The method for preparing the short-cut carbon fiber reinforced polyphenylene sulfide precomposite powder as described in claim 1, characterized in that, In step 3), the coagulant is anhydrous ethanol and ultrapure water; the drying process parameters are: the temperature of the first stage of drying is 80~150℃, and the high vacuum state is maintained for 4~8h; the temperature of the second stage is 120~170℃, and the high vacuum state is maintained for 2~4h.

6. The method for preparing the short-cut carbon fiber reinforced polyphenylene sulfide precomposite powder as described in claim 1, characterized in that, The crushing process parameters in step 4) are: crusher speed 15000rpm, crusher blade distance from the bottom of the machine 0.75cm, crushing temperature 20~50℃, crushing time 10~20min; the sieve mesh specification is 50 mesh.

7. Short-cut carbon fiber reinforced polyphenylene sulfide composite powder prepared by the preparation method according to any one of claims 1-6.

8. The application of the short-cut carbon fiber reinforced polyphenylene sulfide precomposite powder according to claim 7, characterized in that, Short-cut carbon fiber reinforced polyphenylene sulfide pre-composite powder is placed in a mold and hot-pressed to obtain short-cut carbon fiber / polyphenylene sulfide composite material.

9. The application as described in claim 8, characterized in that, The hot pressing process parameters are: pressure 2~15MPa, preheating temperature 310~370℃, preheating time 30~60min, holding temperature 310~370℃, and holding time 10~50min.

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