Anti-static polyether-ether-ketone composite material and preparation method thereof

Abstract

The invention provides an anti-static polyether-ether-ketone composite material and a preparation method thereof, and relates to the technical field of polymer composites.According to the preparation method, carbon nanotubes and conductive carbon black are made to cooperatively construct a primary point + line three-dimensional conductive network through primary granulation, and high conductivity and low orientation are both considered; and continuous carbon fibers are added through secondary granulation and side feeding, so that the breakage of the carbon fibers is reduced to the greatest extent, the mechanical enhancement effect of the carbon fibers is guaranteed, the carbon fibers become bridges for connecting the conductive regions, and the conductivity is stabilized. According to the technical scheme, through the design of the filler morphology and the processing technology, macroscopic, uniform and microcosmic continuous dispersion of the conductive carbon filler is achieved to a certain extent, and balanced improvement of mechanical properties and electrical properties is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer composite materials, and particularly relates to an anti-static polyether ether ketone composite material and a preparation method thereof. BACKGROUND

[0002] Polyether ether ketone (PEEK) has become a key material in high-end manufacturing fields such as aerospace and electronics due to its excellent heat resistance, mechanical strength and chemical stability. However, its extremely high volume resistivity (usually > 10 5 Ω·cm) also causes the material to easily accumulate static electricity, thereby causing problems such as adsorbing dust, interfering with the operation of precision electronic equipment, and even posing a safety hazard in flammable and explosive environments. Therefore, there is an urgent industrial need to develop new composite materials that combine the excellent inherent performance of PEEK with durable and stable anti-static function.

[0003] Currently, the mainstream technical solution is to introduce carbon-based conductive fillers (such as carbon fibers, carbon nanotubes) into the PEEK matrix through blending to build a conductive network. However, this technical path faces two interrelated core technical bottlenecks: 1. Anisotropy and performance unevenness of the conductive network: During high-shear melt processing (such as extrusion, injection molding), fibrous fillers with high aspect ratio will be highly oriented along the flow direction under the action of flow field shear force. This leads to a significant anisotropy in the conductive performance of the composite material: the conductive path along the orientation direction is perfect, and the resistivity is low; while perpendicular to the orientation direction, the contact probability between fillers is greatly reduced, and the conductive path is difficult to form effectively, and the resistivity is significantly higher. As a result, the surface / volume resistivity of the product varies greatly in different parts and directions, the anti-static performance is unreliable and uneven, and the insulation in the thickness direction is too high, which cannot achieve effective static dissipation. 2. Conflict between high filler addition amount and degradation of matrix performance: In order to make up for the lack of vertical direction conductivity caused by filler orientation and ensure that the target resistivity is still achieved under complex flow field, the filler addition amount is often forced to be greatly increased. However, this causes a series of negative effects: on the one hand, the introduction of excessive fillers will sharply increase the melt viscosity of the composite system, leading to poor processing flowability and narrow molding window; on the other hand, excessive fillers act as stress concentration points, severely damaging the toughness of the PEEK matrix (such as a significant decrease in impact strength and elongation at break), and may affect other mechanical properties. In other words, it is difficult to balance excellent anti-static performance and good processability and matrix mechanical properties through simple physical blending.

[0004] Although existing technologies (such as master batch pre-dispersion method) can improve the initial dispersion state of the fillers to some extent, if the three-dimensional spatial distribution morphology of the fillers cannot be precisely regulated, the orientation is inhibited, and the interfacial interaction between the fillers and the matrix is strengthened, the technical problems derived from the orientation and high addition amount of the fillers cannot be fundamentally solved.

[0005] In view of this, it is necessary to design an improved antistatic polyetheretherketone composite material and its preparation method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an antistatic polyether ether ketone composite material and its preparation method.

[0007] To achieve the above-mentioned objectives, in a first aspect, the present invention provides an antistatic polyetheretherketone composite material comprising the following components by mass percentage:

[0008] Polyetheretherketone resin: 85.5-92%;

[0009] Carbon fiber: 5-10%;

[0010] Conductive filler: 3-4.5%;

[0011] The conductive filler is composed of carbon nanotubes and conductive carbon black, with the mass percentage of carbon nanotubes being 1.5-2% and the mass percentage of conductive carbon black being 1.5-2.5%.

[0012] Furthermore, the surface resistivity of the composite material is 10. 6 -10 9 Ω, tensile strength >185MPa, molding shrinkage rate 0.3-0.5%.

[0013] Secondly, the present invention provides a method for preparing an antistatic polyetheretherketone composite material, comprising the following steps:

[0014] S1. After uniformly mixing carbon nanotubes, conductive carbon black and PEEK resin, granulation is performed to obtain mixed resin particles.

[0015] S2. The mixed resin particles obtained in step S1 are fed into an extruder, and carbon fibers are added through the feeding component of the mixing section of the extruder for secondary granulation to obtain an antistatic polyether ether ketone composite material.

[0016] Preferably, the carbon fiber has a mass percentage of 5-10%, the carbon nanotube has a mass percentage of 1.5-2%, the conductive carbon black has a mass percentage of 1.5-2.5%, and the polyetheretherketone resin has a mass percentage of 85.5-92%.

[0017] Preferably, in step S1, the granulation temperature is 370-400℃.

[0018] Preferably, in step S2, the temperature of the secondary granulation is 370-400℃.

[0019] The beneficial effects of this invention are:

[0020] (1) Carbon nanotubes and conductive carbon black are initially dispersed and constructed into a "point + line" three-dimensional conductive pathway after one granulation. Compared with pure conductive carbon black, it has better conductivity, while compared with pure carbon nanotubes, it has lower orientation. The secondary granulation process further shears and disperses these two difficult-to-disperse conductive materials, further breaking up the agglomerates and obtaining a more uniform dispersion.

[0021] (2) Continuous carbon fibers are added by side feeding during the secondary granulation process. On the one hand, this reduces the breakage of carbon fibers during processing, increases the aspect ratio of carbon fibers in the composite material, and improves mechanical properties. On the other hand, carbon fibers are also conductive materials. Their dispersion in the composite material can link various conductive areas and further reduce the surface resistance fluctuation caused by uneven dispersion of carbon nanotubes. Finally, carbon fibers themselves have the characteristics of high strength and high modulus, which can further improve the mechanical properties of the material.

[0022] (3) All three fillers are carbon-based fillers. The cohesive energy between carbon materials is much greater than the adhesion energy between carbon materials and PEEK molecules, making agglomeration a more thermodynamically stable state. Therefore, during the secondary granulation process, small-sized carbon nanotubes and conductive carbon black will accumulate on the carbon fibers and tend to form a connected state, which is more conducive to achieving uniform conductivity. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to specific embodiments.

[0024] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the text, while other details that are not closely related to the present invention are omitted.

[0025] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0026] This invention provides a method for preparing an antistatic polyetheretherketone composite material, comprising the following steps:

[0027] S1. After uniformly mixing carbon nanotubes, conductive carbon black and PEEK resin, granulation is performed to obtain mixed resin particles.

[0028] S2. The mixed resin particles obtained in step S1 are fed into an extruder, and carbon fibers are added through the feeding component of the mixing section of the extruder for secondary granulation to obtain an antistatic polyether ether ketone composite material.

[0029] In some embodiments, the sum of the mass percentages of carbon nanotubes, conductive carbon black, PEEK resin, and carbon fiber is 100%. Specifically, the mass percentage of carbon fiber is 5-10%, the mass percentage of carbon nanotubes is 1.5-2%, the mass percentage of conductive carbon black is 1.5-2.5%, and the mass percentage of polyetheretherketone resin is 85.5-92%. In particular, to avoid the influence of impurities such as moisture in the raw materials on the preparation process, the carbon nanotubes, conductive carbon black, PEEK resin, and carbon fiber can be pre-dried, such as by drying at 140-200°C for 2-5 hours.

[0030] In some embodiments, the granulation temperature in step S1 is 370-400°C.

[0031] In some embodiments, the temperature of the secondary granulation in step S2 is 370-400°C.

[0032] The antistatic polyetheretherketone composite material and its preparation method proposed in this invention will be further described below with reference to specific embodiments:

[0033] Example 1

[0034] This embodiment provides a method for preparing an antistatic polyetheretherketone composite material, comprising the following steps:

[0035] S1. Carbon fiber (purchased from Guangzhou Carbon Composite Materials Co., Ltd., model H2550-12K), carbon nanotubes (purchased from Shandong Dazhan Nanomaterials Co., Ltd., model GT-300), conductive carbon black, and PEEK resin powder were dried at 150℃ for 3 hours. Then, 2 kg of carbon nanotubes, 1.5 kg of conductive carbon black, and 86.5 kg of PEEK resin powder were added to a mechanical mixer and mechanically mixed for 2 hours. The mixture was then granulated using a twin-screw extruder to obtain mixed resin granules.

[0036] S2. The mixed resin granules obtained in step S1 are fed back into a twin-screw extruder, and 10 kg of carbon fiber is uniformly added through the feeding assembly of the extruder's mixing section for secondary granulation to obtain antistatic polyetheretherketone composite material granules. It should be noted that, unless otherwise specified, the reagents and raw materials used in the embodiments of this invention can be obtained commercially.

[0037] Specifically, the twin-screw extruder of this embodiment includes a reverse-threaded element and a kneading block in its screw structure. The reverse-threaded element facilitates uniform mixing of the raw materials during the granulation process in step S1, while the kneading block promotes the dispersion of carbon fibers to ensure the uniformity of the composite material. The twin-screw extruder only needs to achieve the above objectives, and its structure can be adjusted as needed; therefore, a specific structural description is not given here. It should be noted that, unless otherwise specified, the raw materials used in the embodiments of this application can all be obtained through commercial purchase.

[0038] Example 2

[0039] The only difference between Example 2 and Example 1 is that the raw material mass in step S1 is different from that in Example 1, specifically 1.5 kg of carbon nanotubes, 2.5 kg of conductive carbon black, and 86 kg of PEEK resin powder. The other experimental parameters are the same as in Example 1, and will not be repeated here.

[0040] Example 3

[0041] The only difference between Example 3 and Example 1 is that the quality of the raw materials used is different from that in Example 1. Specifically, it consists of 2 kg of carbon nanotubes, 2.5 kg of conductive carbon black, 90.5 kg of PEEK resin powder, and 5 kg of carbon fiber. The other experimental parameters are the same as those in Example 1, and will not be repeated here.

[0042] Comparative Example 1

[0043] The only difference between Comparative Example 1 and Example 1 is that step S2 is omitted, that is, carbon fiber is not added and secondary granulation is not performed, and the mixed resin particles are directly used as composite material particles. The other experimental parameters are the same as those in Example 1, and will not be repeated here.

[0044] Comparative Example 2

[0045] The only difference between Comparative Example 2 and Example 1 is that carbon fiber is not added, and the raw material mass in step S1 is different from that in Example 1, specifically 2.5 kg carbon nanotubes, 1.5 kg conductive carbon black, and 96 kg PEEK resin powder. The other experimental parameters are the same as those in Example 1, and will not be repeated here.

[0046] Comparative Example 3

[0047] The only difference between Comparative Example 3 and Example 1 is that carbon fiber is not added, and the raw material mass in step S1 is different from that in Example 1, specifically 4.5 kg carbon nanotubes, 1.5 kg conductive carbon black, and 94 kg PEEK resin powder. The other experimental parameters are the same as those in Example 1, and will not be repeated here.

[0048] The properties of the composite material particles prepared under the processes and corresponding conditions of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1. Comparing the product performance parameters of Comparative Example 1 and Example 1, it can be found that the tensile strength of the product in Comparative Example 1 is significantly lower than that of the product in Example 1. This is due to the poor dispersion of carbon nanotubes. At the same time, the surface resistance fluctuation range of the material in Comparative Example 1 is also larger, which is due to the poor construction of micro-conductive pathways.

[0049] The surface resistance of the product in Comparative Example 2 is similar to that of Example 1, but its tensile strength is much lower. This is because: among the three fillers, carbon nanotubes have the best electrical conductivity, but due to the difficulty in dispersing nanoparticles, their sharing of material mechanical properties is far less than that of carbon fibers. Additionally, the material in Comparative Example 2 exhibits larger fluctuations in surface resistance and increased molding shrinkage. The surface resistance and tensile strength of the product in Comparative Example 3 are both lower than those in Comparative Example 2. This is because the aggregation of carbon nanotubes causes internal defects in the material. The higher the content of carbon nanotubes, the more severe the defects. This directly leads to the formation of carbon clusters within PEEK, making it difficult to establish conductive pathways and causing stress concentration, thus reducing the material's mechanical strength.

[0050] Table 1. Process and composite material particle performance results of Examples 1 to 3 and Comparative Examples 1 to 3

[0051]

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An antistatic polyether ether ketone composite material, characterized by, Comprise the following components by mass percentage: Polyether ether ketone resin: 85.5-92%; Carbon fiber: 5-10%; Conductive filler: 3-4.5%; The conductive filler is composed of carbon nanotubes and conductive carbon black, and the mass percentage of carbon nanotubes is 1.5-2%, and the mass percentage of conductive carbon black is 1.5-2.5%.

2. The composite material of claim 1, wherein, The surface resistance of the composite material is 10 6 -10 9 Ω, tensile strength > 185 MPa, and molding shrinkage is 0.3-0.5%.

3. A method for the production of the antistatic polyether ether ketone composite material according to claim 1 or 2, characterized in that Comprise the following steps: S1, after mixing carbon nanotubes, conductive carbon black and PEEK resin uniformly, granulation, prepared mixed resin particles; S2, the mixed resin particles prepared in step S1 are put into the extruder, and carbon fibers are added through the feeding assembly of the mixing section of the extruder, secondary granulation, prepared anti-static polyether ether ketone composite material.

4. The production method according to claim 3, characterized by, The mass percentage of carbon fiber is 5-10%, the mass percentage of carbon nanotube is 1.5-2%, the mass percentage of conductive carbon black is 1.5-2.5%, and the mass percentage of polyether ether ketone resin is 85.5-92%.

5. The preparation method according to claim 3, characterized in that, In step S1, the temperature of granulation is 370-400℃.

6. The preparation method according to claim 3, characterized in that, In step S2, the temperature of secondary granulation is 370-400℃.

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