Long carbon fiber reinforced conductive and heat-conducting polyphenylene sulfide composite material and preparation method thereof

Abstract

The invention discloses a long carbon fiber reinforced electric conduction and heat conduction polyphenylene sulfide composite material and a preparation method thereof, the composite material comprises the following components by mass: 40-80 parts of matrix resin, 5-40 parts of reinforced fiber, 5-20 parts of an electric conduction and heat conduction agent, and 0-5 parts of an auxiliary agent. According to the scheme, the continuous long carbon fibers and the compound electricity and heat conduction agent synergistically construct a perfect three-dimensional network, and high heat conduction (3.5-12 W / (mK)) and low resistivity (10-10 omegacm) are achieved under the condition of low filler content; through the long carbon fiber high retention length and an interface modification technology, the tensile strength reaches 150-320 MPa, the bending modulus is 15-40 GPa, and the mechanical property is excellent. Gradient temperature control and auxiliary agent compounding guarantee the processing stability, and the melt flow rate and formability are good; the thermal deformation temperature of the material is 200-260 DEG C, the material is stable in acid and alkali resistance and thermal aging, the adaptability to the environment of-40-200 DEG C is high, and the molding shrinkage rate is only 0.2%-0.8%. The system has multifunctional integration and wide scene adaptability, and is suitable for the fields of high-end electronics, automobiles, aerospace and the like.

Description

Technical Field

[0001] This invention relates to a long carbon fiber reinforced electrical and thermally conductive polyphenylene sulfide composite material and its preparation method. Background Technology

[0002] Polyphenylene sulfide (PPS), a high-performance crystalline engineering plastic, possesses excellent high-temperature resistance (melting point approximately 286℃), chemical corrosion resistance, flame retardancy, and mechanical strength, and is widely used in electronics, automotive manufacturing, aerospace, and other fields. With the increasing demand for multifunctional integrated materials in modern industry, PPS composite materials are required to maintain their original excellent properties while also possessing good electrical and thermal conductivity to address heat dissipation and static electricity accumulation issues during equipment operation.

[0003] In existing technologies, the main methods to improve the electrical and thermal conductivity of PPS composites include adding conductive and thermally conductive fillers (such as short carbon fibers, carbon black, graphite, etc.) and modifying the reinforcing fibers. However, these technical solutions have significant drawbacks:

[0004] (1) In the short fiber reinforced system, the short carbon fiber has a limited length, making it difficult to form a continuous conductive and thermally conductive path. A large amount of filler needs to be added to achieve the target performance, which leads to a decrease in material processing fluidity, an increase in cost, and a limited improvement in mechanical properties.

[0005] (2) In the long carbon fiber reinforcement technology, there are problems such as insufficient fiber impregnation, uneven dispersion of monofilaments, and weak interfacial bonding between fiber and PPS matrix, which lead to defects in the composite material, unstable electrical and thermal conductivity, and failure to fully utilize mechanical properties.

[0006] (3) It is difficult to construct a perfect three-dimensional network with a single conductive and thermally conductive agent, which has the problems of "high percolation threshold and performance improvement bottleneck". In addition, high filler content can easily lead to a decrease in the material's aging resistance and processing stability.

[0007] (4) During the processing, PPS resin is prone to thermal decomposition due to improper temperature control, and long carbon fibers are prone to breakage under shear force, which further affects the overall performance of the material. Summary of the Invention

[0008] The purpose of this invention is to provide a long carbon fiber reinforced conductive and thermally conductive polyphenylene sulfide composite material and its preparation method, so as to solve the technical problems existing in the background art.

[0009] This invention provides a polyphenylene sulfide composite material reinforced with long carbon fibers for electrical and thermal conductivity, comprising the following components by weight: 40-80 parts of matrix resin, 5-40 parts of reinforcing fibers, 5-20 parts of conductive and thermally conductive agent, and 0-5 parts of additives; wherein the matrix resin is polyphenylene sulfide (PPS) with a weight-average molecular weight of not less than 3.0 × 10⁻⁶. 5 The reinforcing fiber is a continuous long carbon fiber; the conductive and thermally conductive agent is one or more of high thermal conductivity graphite, high thermal conductivity carbon black, and carbon nanotubes; the additive is one or more of coupling agents, antioxidants, and processing aids.

[0010] In a preferred embodiment, the polyphenylene sulfide (PPS) is a high molecular weight linear polyphenylene sulfide or a cross-linked polyphenylene sulfide.

[0011] In a preferred embodiment, the continuous long carbon fiber is a pitch-based carbon fiber filament with a single filament diameter of 5-15 μm and a fiber bundle denier of 1000-3000 denier.

[0012] In a preferred embodiment, the composite system of the conductive and thermally conductive agent is a combination of high thermal conductivity graphite and carbon nanotubes, a combination of high thermal conductivity carbon black and carbon nanotubes, or a ternary combination of high thermal conductivity graphite, high thermal conductivity carbon black and carbon nanotubes, wherein the mass ratio of each component in the ternary combination is high thermal conductivity graphite: high thermal conductivity carbon black: carbon nanotubes = (3-5): (1-2): (0.5-1).

[0013] In a preferred embodiment, the coupling agent is silane coupling agent KH590, the antioxidant is a compound system of 1010 and 168 with a compound mass ratio of 1:1 to 1:2, and the processing aid is silicone powder; the total mass of the aids is 0.5-5 parts, wherein the coupling agent accounts for 30%-50% of the total mass of the aids.

[0014] A method for preparing a long carbon fiber reinforced electrical and thermally conductive polyphenylene sulfide composite material includes the following steps:

[0015] S1, Fiber pretreatment: Continuous long carbon fibers are drawn out from the yarn rack, the tension is adjusted by the tension control system, and then preheated by the preheating device to remove moisture from the fiber surface and keep the fiber straight.

[0016] S2, Melt Impregnation: The pre-molten polyphenylene sulfide resin and the continuous long carbon fiber pretreated in step S1 are introduced into the impregnation die. Under the temperature conditions of 265-290℃ and the preset pressure, turbulence is formed through the narrow flow channel in the die, and the fiber bundle is uniformly dispersed by passing around the tension roller in the die, ensuring that the resin fully covers and impregnates each carbon fiber filament.

[0017] S3, Cooling, Shaping and Pelletizing: The continuous fiber / PPS prepreg impregnated in step S2 is extruded from the die and immediately fed into a cooling water tank for curing and shaping. After being pulled by a traction machine, it is cut into pellets with a length of 6-18 mm by a precision pelletizer to obtain the composite material.

[0018] In a preferred embodiment, step S1 further includes surface modification treatment of continuous long carbon fibers: the preheated carbon fibers are immersed in a coupling agent aqueous solution with a mass concentration of 1%-3%, ultrasonically treated for 20-40 minutes, and then dried at 110-130°C to constant weight, and then the subsequent melt impregnation step is carried out.

[0019] In a preferred embodiment, the preheating temperature in step S1 is 80-120°C and the preheating time is 10-30 min; in step S2, the pressure inside the impregnation die is controlled at 5-15 MPa and the residence time of the fiber bundle inside the die is 3-10 s.

[0020] In a preferred embodiment, the preparation process of the molten polyphenylene sulfide resin in step S2 is as follows: the polyphenylene sulfide resin, conductive and thermally conductive agent and additives are added to the feed port of the twin-screw extruder in proportion, and after being mixed by temperature-controlled partitioning to form a uniform molten material, it is then conveyed to the impregnation die head to be composited with continuous long carbon fibers.

[0021] In a preferred embodiment, in step S2, a twin-screw extruder is used to provide molten polyphenylene sulfide resin. The temperature of the twin-screw extruder from the feed port to the die head is set in a gradient, specifically: Zone 1 270-275℃, Zone 2 285-290℃, Zone 3 295-300℃, Zone 4 300-305℃, Zone 5 295-300℃, Zone 6 290-295℃, Zone 7 290-295℃, Zone 8 290-295℃, and the die head 295-300℃, to ensure that the material is fully plasticized and does not undergo thermal decomposition.

[0022] The beneficial effects of the technical solution of this invention are:

[0023] This solution exhibits excellent electrical and thermal conductivity: continuous long carbon fibers form the main electrical and thermal conductivity pathways, and compounded electrical and thermal conductivity agents fill the gaps. With a total content of only 5-20 parts of electrical and thermal conductivity agents, the thermal conductivity of the composite material can reach 3.5-12 W / (m・K), and the volume resistivity is as low as 10⁻²-10² Ω・cm, which is far superior to the existing short fiber + single filler system.

[0024] The mechanical properties of this solution are outstanding: through tension control, preheating treatment and coupling agent modification, long carbon fibers maintain a high retention length of 6-18mm and axial parallel orientation in the composite material, significantly improving the interfacial bonding force, with tensile strength reaching 150-320MPa and flexural modulus reaching 15-40GPa, meeting the requirements for structural components.

[0025] This solution offers good processing stability: the gradient temperature control of the twin-screw extruder prevents thermal decomposition of PPS resin, silicone powder processing aids improve melt flowability, and the granules have excellent formability. They can be processed through conventional processes such as injection molding and extrusion, resulting in high production efficiency.

[0026] This solution exhibits strong environmental adaptability: the high-temperature resistance and chemical corrosion resistance of the PPS matrix, combined with the synergistic effect of antioxidants, ensures stable performance of the composite material during long-term use in environments ranging from -40°C to 200°C. It is resistant to acids, alkalis, and organic solvents, making it suitable for a wide range of applications. Detailed Implementation

[0027] The present invention will now be described in further detail. The embodiments of the invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0028] Example 1

[0029] 1. Composite material components (parts by mass)

[0030] Matrix resin: High molecular weight linear PPS (weight average molecular weight 3.2 × 10⁻⁶) 5 65 copies;

[0031] Reinforcing fiber: 20 parts of pitch-based continuous long carbon fiber (monofilament diameter 8μm, fiber bundle denier 2000 denier);

[0032] Conductive and thermally conductive agent: 10 parts of high thermal conductivity graphite + 2 parts of carbon nanotubes (mass ratio 5:1);

[0033] Additives: 1 part of silane coupling agent KH590 + 0.5 parts of antioxidant (1010:168=1:1) + 0.3 parts of silicone powder, totaling 1.8 parts.

[0034] 2. Preparation method

[0035] S1: Fiber pretreatment: Continuous long carbon fibers are drawn out, tension is controlled at 5N, and preheated at 80℃ for 20min; the preheated carbon fibers are immersed in a 2% KH590 aqueous solution, ultrasonically treated for 30min, and dried at 120℃ to constant weight.

[0036] S2: Preparation of molten material: PPS resin, conductive and thermally conductive agent and additives are added to a twin-screw extruder. The temperature gradient is set as follows: Zone 1 270℃, Zone 2 285℃, Zone 3 295℃, Zone 4 305℃, Zone 5 300℃, Zone 6 295℃, Zone 7 290℃, Zone 8 290℃, and the die head 300℃. After plasticizing and mixing, molten material is formed.

[0037] S3: Melt impregnation: Molten material and modified carbon fiber are introduced into the impregnation die head. The die head pressure is 8MPa and the fiber bundle residence time is 5s. Full impregnation is achieved through turbulent flow in the slit channel and dispersion by the tension roller.

[0038] S4: Cooling, shaping and pelletizing: After extrusion, the pellets are shaped in a cooling water tank, the traction machine speed is 2m / min, and the precision pelletizer cuts them into pellets with a length of 12mm.

[0039] Example 2

[0040] 1. Composite material components (parts by mass)

[0041] Matrix resin: Cross-linked PPS (weight average molecular weight 3.5 × 10⁻⁶) 5 50 copies;

[0042] Reinforcing fiber: 30 parts of pitch-based continuous long carbon fiber (monofilament diameter 12μm, fiber bundle denier 3000 denier);

[0043] Conductive and thermally conductive agent: 8 parts high thermal conductivity graphite + 4 parts high thermal conductivity carbon black + 1 part carbon nanotube (mass ratio 8:4:1).

[0044] Additives: 1.5 parts of silane coupling agent KH590 + 0.8 parts of antioxidant (1010:168=1:2) + 0.7 parts of silicone powder, totaling 3.0 parts.

[0045] 2. Preparation method

[0046] S1: Fiber pretreatment: tension controlled at 8N, preheated at 100℃ for 15min; soaked in 3% KH590 aqueous solution, ultrasonically treated for 40min, and dried at 130℃ to constant weight;

[0047] S2: Preparation of molten material: The temperature gradient of the twin screw is 275℃ in zone 1, 290℃ in zone 2, 300℃ in zone 3, 305℃ in zone 4, 290℃ in zone 5, 290℃ in zone 6, 295℃ in zone 7, 295℃ in zone 8, and 295℃ at the die head.

[0048] S3: Melt impregnation: Die head pressure 12MPa, fiber bundle residence time 8s;

[0049] S4: Cooling, shaping and pelletizing: Cut into pellets with a length of 15mm, and the other parameters are the same as in Example 1.

[0050] Example 3

[0051] 1. Composite material components (parts by mass)

[0052] Matrix resin: Linear PPS (weight average molecular weight 3.0 × 10⁻⁶) 5 75 copies;

[0053] Reinforcing fiber: 10 parts of pitch-based continuous long carbon fiber (5μm diameter per filament, 1000 denier per bundle);

[0054] Conductive and thermally conductive agent: 6 parts high thermal conductivity carbon black + 1 part carbon nanotubes (mass ratio 6:1).

[0055] Additives: 0.5 parts antioxidant (1010:168=1:1.5) + 0.5 parts silicone powder, totaling 1.0 part (without coupling agent).

[0056] 2. Preparation method

[0057] S1: Fiber pretreatment: tension controlled at 3N, preheated at 120℃ for 10min, no surface modification treatment;

[0058] S2: Preparation of molten material: The temperature gradient of the twin screw is 275℃ in zone 1, 290℃ in zone 2, 300℃ in zone 3, 305℃ in zone 4, 300℃ in zone 5, 295℃ in zone 6, 290℃ in zone 7, 290℃ in zone 8, and 300℃ at the die head.

[0059] S3: Melt impregnation: Die head pressure 5MPa, fiber bundle residence time 3s;

[0060] S4: Cooling, shaping, and pelletizing: Cut into 8mm long pellets, with other parameters the same as in Example 1.

[0061] Comparative Example 1 (Prior Art)

[0062] 1. Composite material components (parts by mass)

[0063] Matrix resin: Linear PPS (weight average molecular weight 3.0 × 10⁻⁶) 5 65 copies;

[0064] Reinforcing fiber: 20 parts of short carbon fibers (0.5 mm in length and 8 μm in diameter);

[0065] Electrical and thermal conductive agent: 12 parts of single high thermal conductivity graphite;

[0066] Additive: 0.3 parts silicone powder

[0067] 2. Preparation method

[0068] The compounding process was carried out using a conventional twin-screw extruder with a temperature gradient of 275-305℃. After extrusion, the pellets were cut into granules with a length of 3mm.

[0069] Performance testing

[0070] The composite material granules of Examples 1-3 and Comparative Example 1 were injection molded to prepare standard test strips, and their performance was tested according to the following standards:

[0071] Tensile strength: GB / T 1040.1-2006;

[0072] Flexural modulus: GB / T 9341-2008;

[0073] Thermal conductivity: GB / T 22588-2008;

[0074] Volume resistivity: GB / T 1410-2006;

[0075] Thermal aging stability: Tensile strength retention rate was tested after aging at 200℃ for 1000h.

[0076] The test results are shown in the table below:

[0077] Performance indicators Example 1 Example 2 Example 3 Comparative Example 1 Tensile strength (MPa) 245 302 186 128 Flexural modulus (GPa) 28.5 36.8 20.3 12.5 Thermal conductivity (W / (m・K)) 8.6 11.2 4.2 2.1 Volume resistivity (Ω·cm) <![CDATA[1.2×10 0 ]]> 8.5×10⁻¹ 3.6×10¹ 2.8×10³ Tensile strength retention rate after aging at 200℃ for 1000 hours (%) 92.3 94.1 88.7 76.5

[0078] The test results show that:

[0079] The composite materials of Examples 1-3 are significantly better than those of Comparative Example 1 in terms of tensile strength, flexural modulus, thermal conductivity and volume resistivity, which proves that the synergistic effect of continuous long carbon fibers and compounded conductive and thermally conductive agents can greatly improve the mechanical properties and electrical and thermal conductivity of the materials.

[0080] Example 2 (high long carbon fiber content + ternary composite conductive and thermally conductive agent + interface modification) has the best overall performance, with a thermal conductivity of 11.2 W / (m・K) and a tensile strength of 302 MPa, demonstrating the synergistic effect of component optimization and process improvement.

[0081] Example 3: No coupling agent was used for interface modification. The mechanical properties and thermal aging stability were slightly lower than those of Examples 1-2, which proves the important role of coupling agent in improving the interfacial bonding force between fiber and matrix.

[0082] Comparative Example 1, due to the use of short carbon fibers and a single conductive agent, is difficult to form a continuous network, resulting in poor electrical and thermal conductivity and mechanical properties, as well as insufficient thermal aging stability, further highlighting the superiority of the technical solution of this invention.

[0083] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A polyphenylene sulfide composite material reinforced with long carbon fibers for electrical and thermal conductivity, characterized in that, By weight, it includes the following components: 40-80 parts of matrix resin, 5-40 parts of reinforcing fiber, 5-20 parts of conductive and thermally conductive agent, and 0-5 parts of additives; The matrix resin is polyphenylene sulfide (PPS), with a weight-average molecular weight of not less than 3.0 × 10⁻⁶. 5 ; The reinforcing fiber is a continuous long carbon fiber; the conductive and thermally conductive agent is one or more of the following: high thermal conductivity graphite, high thermal conductivity carbon black, and carbon nanotubes; the additive is one or more of the following: coupling agent, antioxidant, and processing aid.

2. The polyphenylene sulfide composite material reinforced with long carbon fibers for electrical and thermal conductivity according to claim 1, characterized in that, The polyphenylene sulfide (PPS) is a high molecular weight linear polyphenylene sulfide or a cross-linked polyphenylene sulfide.

3. The polyphenylene sulfide composite material reinforced with long carbon fibers for electrical and thermal conductivity according to claim 1, characterized in that, The continuous long carbon fiber is a pitch-based carbon fiber filament with a single filament diameter of 5-15μm and a fiber bundle denier of 1000-3000.

4. The polyphenylene sulfide composite material reinforced with long carbon fibers for electrical and thermal conductivity according to claim 1, characterized in that, The composite system of the conductive and thermally conductive agent is a combination of high thermal conductivity graphite and carbon nanotubes, a combination of high thermal conductivity carbon black and carbon nanotubes, or a ternary combination of high thermal conductivity graphite, high thermal conductivity carbon black and carbon nanotubes. In the ternary combination, the mass ratio of each component is high thermal conductivity graphite: high thermal conductivity carbon black: carbon nanotubes = (3-5): (1-2): (0.5-1).

5. The polyphenylene sulfide composite material reinforced with long carbon fibers for electrical and thermal conductivity according to claim 1, characterized in that, The coupling agent is silane coupling agent KH590, the antioxidant is a compound system of 1010 and 168 with a compound mass ratio of 1:1 to 1:2, and the processing aid is silicone powder; the total mass of the aids is 0.5-5 parts, of which the coupling agent accounts for 30%-50% of the total mass of the aids.

6. A method for preparing a long carbon fiber reinforced conductive and thermally conductive polyphenylene sulfide composite material according to any one of claims 1-5, characterized in that, Includes the following steps: S1, Fiber pretreatment: Continuous long carbon fibers are drawn out from the yarn rack, the tension is adjusted by the tension control system, and then preheated by the preheating device to remove moisture from the fiber surface and keep the fiber straight. S2, Melt Impregnation: The pre-molten polyphenylene sulfide resin and the continuous long carbon fiber pretreated in step S1 are introduced into the impregnation die. Under the temperature conditions of 265-290℃ and the preset pressure, turbulence is formed through the narrow flow channel in the die, and the fiber bundle is uniformly dispersed by passing around the tension roller in the die, ensuring that the resin fully covers and impregnates each carbon fiber filament. S3, Cooling, Shaping and Pelletizing: The continuous fiber / PPS prepreg impregnated in step S2 is extruded from the die and immediately fed into a cooling water tank for curing and shaping. After being pulled by a traction machine, it is cut into pellets with a length of 6-18 mm by a precision pelletizer to obtain the composite material.

7. The method for preparing a long carbon fiber reinforced conductive and thermally conductive polyphenylene sulfide composite material according to claim 6, characterized in that, Step S1 also includes surface modification treatment of continuous long carbon fibers: the preheated carbon fibers are immersed in a coupling agent aqueous solution with a mass concentration of 1%-3%, ultrasonically treated for 20-40 minutes, and then dried at 110-130℃ to constant weight before proceeding with the subsequent melt impregnation step.

8. The method for preparing a long carbon fiber reinforced conductive and thermally conductive polyphenylene sulfide composite material according to claim 6, characterized in that, In step S1, the preheating temperature is 80-120℃ and the preheating time is 10-30min; in step S2, the pressure inside the impregnation die is controlled at 5-15MPa and the residence time of the fiber bundle inside the die is 3-10s.

9. The method for preparing a long carbon fiber reinforced conductive and thermally conductive polyphenylene sulfide composite material according to claim 6, characterized in that, The preparation process of molten polyphenylene sulfide resin in step S2 is as follows: polyphenylene sulfide resin, conductive and thermally conductive agent and additives are added to the feed port of twin screw extruder in proportion. After being plasticized and mixed at different temperature zones, a uniform molten material is formed, which is then conveyed to the impregnation die head and compounded with continuous long carbon fibers.

10. The method for preparing a long carbon fiber reinforced conductive and thermally conductive polyphenylene sulfide composite material according to claim 6, characterized in that, In step S2, a twin-screw extruder is used to supply molten polyphenylene sulfide resin. The temperature of the twin-screw extruder from the feed port to the die head is set in a gradient, specifically: Zone 1 270-275℃, Zone 2 285-290℃, Zone 3 295-300℃, Zone 4 300-305℃, Zone 5 295-300℃, Zone 6 290-295℃, Zone 7 290-295℃, Zone 8 290-295℃, and the die head 295-300℃, to ensure that the material is fully plasticized and does not undergo thermal decomposition.