High-strength, high-toughness and high-thermal-stability PA66 composite material and preparation method thereof

Abstract

This invention discloses a high-strength, high-toughness, and high-thermal-stability PA66 composite material and its preparation method. The PA66 composite material is composed of PA66 resin, modified chopped glass fiber, toughening agent, composite heat resistant agent, high-efficiency nucleating agent, color masterbatch, and lubricant. The preparation steps are as follows: Step (1): PA66 resin, composite heat resistant agent, high-efficiency nucleating agent, toughening agent, color masterbatch, and lubricant are mixed in a high-speed mixer to obtain a premix; Step (2): The premix is ​​added from the main feed port of a twin-screw extruder, and the modified chopped glass fiber is introduced from the side feed port of the twin-screw extruder. The side feed port is located after the melting section of the cylinder and before the vacuum exhaust port; after melt mixing and vacuum devolatilization, the material is extruded, cooled, and pelletized to obtain composite material particles. The PA66 composite material of this invention has high breaking strength, good toughness, and excellent long-term thermal stability, making it suitable for high-temperature and high-strength working conditions.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, and relates to a PA66 composite material and its preparation method. Specifically, it relates to a high-performance PA66 composite material with PA66 as the matrix and modified by a variety of functional additives, and its preparation method. Background Technology

[0002] PA66 is widely used in aerospace, automotive, and electronics industries due to its excellent mechanical properties, wear resistance, and self-lubricating properties. However, pure PA66 has limited tensile strength and a relatively low heat distortion temperature, making it prone to performance degradation under long-term use in high-temperature environments. This limits its application in high-temperature environments such as engine compartments.

[0003] Currently, glass fiber reinforcement is commonly used to improve the strength and heat resistance of PA66. However, simple glass fiber reinforcement leads to a decrease in material toughness, and under high heat loads, the material matrix is ​​prone to thermo-oxidative aging, resulting in a sharp decline in performance. Conventional single antioxidant systems cannot meet the stability requirements under long-term high temperatures. In existing technologies, how to achieve the optimal balance between high strength, high toughness, and high thermal stability through formulation design, and to realize stable and efficient industrial production, remains a technical challenge. Summary of the Invention

[0004] To address the common problems of "strong but not tough" or "insufficient thermal stability" in existing glass fiber reinforced PA66 materials, this invention provides a high-strength, high-toughness, and high-thermal-stability PA66 composite material and its preparation method. This material significantly improves its toughness while maintaining high breaking strength, and ensures excellent performance retention under long-term high-temperature conditions. Furthermore, it features a stable processing window, making it suitable for precision structural components with extremely high overall performance requirements. The PA66 composite material of this invention combines high breaking strength, good toughness, and excellent long-term thermal stability, making it suitable for high-temperature and high-strength applications.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A high-strength, high-toughness, and high-thermal-stability PA66 composite material, by weight, is composed of 50-65 parts PA66 resin, 25-38 parts modified chopped glass fiber, 3-10 parts toughening agent, 0.5-1.5 parts composite heat resistant agent, 0.1-0.6 parts high-efficiency nucleating agent, 0.5-2.0 parts color masterbatch, and 0.2-0.8 parts lubricant.

[0007] A method for preparing the above-mentioned high-strength, high-toughness, and high-thermal-stability PA66 composite material includes the following steps:

[0008] Step (1) Premixing: Place PA66 resin, composite heat resistant agent, high-efficiency nucleating agent, toughening agent, color masterbatch and lubricant in a high-speed mixer and mix for 3-5 minutes to obtain premix;

[0009] Step (2) Melt blending and extrusion granulation: The premixed material is added from the main feed port of the twin-screw extruder, and the modified chopped glass fiber is introduced from the side feed port of the twin-screw extruder. The side feed port is located after the melting section of the barrel and before the vacuum exhaust port. After melt blending and vacuum devolatilization, the material is extruded, cooled, and granulated to obtain composite material particles. The screw speed of the twin-screw extruder is 180~220 rpm, and the barrel temperature increases gradually from the feed port to the die head in the range of 245℃ to 280℃.

[0010] Application of the above-mentioned high-strength, high-toughness and high-thermal-stability PA66 composite material in the preparation of peripheral structural parts and housings for automobiles and aero-engines.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1. A triple synergistic effect of strength, toughness, and stability: PA66 EPR32D (high-strength matrix) + modified Taishan glass fiber (reinforcement) + POEFB521A (toughening) + HS01 (thermal stability) + CAV102 (crystallization optimization) constitute a precise synergistic system. This system, while ensuring high fracture strength, significantly improves the material's toughness (such as impact strength) through the introduction of POE, and through the synergistic effect of HS01 and CAV102, endows the material with unparalleled long-term thermal stability.

[0013] 2. Perfect Match Between Process and Formulation: The specific low-speed process of 200 rpm is highly compatible with the aforementioned multi-component system. Its gentle processing characteristics protect the structural integrity of functional components (especially glass fiber and POE), which is a key guarantee for achieving the final excellent performance and also makes the production process more stable and controllable.

[0014] 3. Directly usable end-use materials: By adding a specific color masterbatch JER6112, the materials are made to be the desired color when they leave the factory, avoiding performance fluctuations and quality risks that may be caused by downstream customers having to match colors again, thereby enhancing the added value and market competitiveness of the products. Detailed Implementation

[0015] The technical solution of the present invention will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0016] This invention provides a high-strength, high-toughness, and high-thermal-stability PA66 composite material, which, by weight, comprises the following components:

[0017] PA66 resin: 50~65 parts, preferably EPR32D (Shenma Industrial Co., Ltd.), whose high intrinsic viscosity provides good matrix bearing capacity.

[0018] Modified chopped glass fiber: 25-38 parts, preferably modified chopped glass fiber from Taishan Glass Fiber Co., Ltd., whose surface treatment agent has better compatibility with PA66 matrix, which is beneficial to improving interfacial bonding strength.

[0019] Toughening agent: 3-10 parts, preferably POE FB521A (Jia Yi Rong Polymer Co., Ltd.), specifically composed of maleic anhydride (MAH) grafted modified polyolefin elastomer. This toughening agent uses a semi-crystalline ethylene copolymer as the matrix, and maleic anhydride functional groups are grafted through reactive extrusion. The grafting rate is slightly higher than that of similar imported products, allowing it to maintain the excellent flexibility and elasticity of polyolefin elastomer while reacting with the terminal amino groups of PA66 to form a good interfacial bond. This effectively improves the room temperature and low temperature toughness of nylon materials, while maximizing the fluidity and processing stability of the system.

[0020] Composite heat resistant agent: 0.5~1.5 parts, preferably brand HS01 (Shanghai Ruijingcheng Functional Materials Co., Ltd.), composed of a primary antioxidant (hindered phenolic), a secondary antioxidant (phosphite), and a metal passivator in a weight ratio of 1~2:1~2:0.5~1. The primary antioxidant is preferably pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), used to capture free radicals; the secondary antioxidant is preferably tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), used to decompose hydrogen peroxide; the metal passivator is preferably N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexamethylenediamine, used to chelate and passivate metal ions introduced by glass fiber and processing. The combination of these three components produces a synergistic effect, significantly improving the long-term thermo-oxidative stability of the material.

[0021] Highly efficient nucleating agent: 0.1~0.6 parts, preferably CAV102 (Clariant Chemicals Ltd.), specifically composed of: calcium salt of long-chain saturated linear carboxylic acid (lignite), chemically named calcium lignite, with the chemical formula C... 28 H 55 CaO2 and CAV102 can promote the rapid crystallization of PA66 to form fine spherulites, thereby improving crystallinity, mechanical properties, and shortening the injection molding cycle. They also have lubricating and demolding effects.

[0022] Color masterbatch: 0.5~2.0 parts, preferably JER6112 (Shanghai Ruijingcheng New Material Technology Co., Ltd.). This color masterbatch carrier has good compatibility with PA66, avoiding performance degradation due to the addition of color masterbatch.

[0023] Lubricant: 0.2~0.8 parts, preferably calcium stearate S (Faji Chemicals (Zhangjiagang) Co., Ltd.), the specific component is calcium stearate, chemical name is calcium octadecanoate, molecular formula is Ca(C 18 H 35 O2)2. Calcium stearate S can reduce the internal friction between polymer molecular chains and the external friction between the polymer and the surface of the processing equipment during the processing of PA66, improve melt flowability, prevent melt fracture, and at the same time have a certain demolding effect without affecting the subsequent spraying and welding performance of the product.

[0024] A method for preparing the above-mentioned high-strength, high-toughness, and high-thermal-stability PA66 composite material includes the following steps:

[0025] Step (1) Premixing: Place PA66 resin, composite heat resistant agent, high-efficiency nucleating agent, toughening agent, color masterbatch and lubricant in a high-speed mixer and mix for 3 to 5 minutes at room temperature until uniform.

[0026] Step (2) Melt blending and extrusion granulation:

[0027] Equipment: Co-rotating twin-screw extruder.

[0028] Feeding method: The premixed material is added from the main feed port; the modified chopped glass fiber is introduced from the side feed port in the middle and rear of the melting section.

[0029] Core process parameters:

[0030] Temperature settings: The cylinder temperature gradually increases from the feed port to the die head within the range of 245℃ to 280℃. Zone 1: 245~250℃, Zone 2: 255~265℃, Zone 3: 265~270℃, Zone 4: 270~275℃, Zone 5: 275~280℃, and the die head temperature is 275~280℃.

[0031] Screw speed: 180~220 rpm, preferably 200 rpm (corresponding to a frequency of about 50Hz). This relatively low speed is one of the key process features of the present invention, and its advantages are: (1) reducing shear heat and preventing excessive degradation of heat-sensitive components such as PA66 and heat-resistant agents. (2) reducing mechanical shear damage to the glass fiber and toughening agent elastomer phase, better maintaining the glass fiber aspect ratio and elastomer particle morphology, thereby more effectively exerting its reinforcing and toughening effects. (3) moderately extending the melt residence time, which is conducive to the full dispersion and plasticization of each component.

[0032] Vacuum exhaust: A vacuum exhaust port is set after the glass fiber feed port, with a vacuum degree ≥ -0.08 MPa.

[0033] The composite material particles are obtained by extrusion through a die, water cooling, drying, and pelletizing.

[0034] This invention combines the synergistic compounding of specific grade functional additives with a low-speed and mild process, enabling the material to possess both excellent mechanical properties and long-term thermal stability. Its tensile modulus is >2400MPa, and its dimensional stability is ≤0.4% after 6 hours of heat aging at 220℃. It is particularly suitable for automotive, aerospace engine components and other fields with stringent requirements for comprehensive performance.

[0035] Example:

[0036] 1. Raw materials and equipment

[0037] PA66: EPR32D, Shenma Industry.

[0038] Glass fiber: Modified chopped glass fiber (such as T435 / B), Taishan glass fiber.

[0039] Toughening agent: POE FB521A, Jia Yi Rong.

[0040] Composite heat resistant agent: HS01, Shanghai Ruijingcheng.

[0041] Nucleating agent: CAV102, Clariant.

[0042] Color masterbatch: JER6112, Shanghai Ruijingcheng.

[0043] Lubricant: Calcium stearate S, hair-based chemicals.

[0044] Twin-screw extruder: length-to-diameter ratio 40:1~48:1.

[0045] Injection molding machines, tensile testing machines, impact testing machines, drying ovens, etc.

[0046] 2. Examples and Comparative Examples (parts by weight)

[0047]

[0048] 3. Performance Testing and Results

[0049]

[0050] Examples 1 and 2 demonstrate a perfect balance between high tensile modulus and high heat resistance. The addition of POE FB521A significantly improves toughness (elongation at break), while the complete heat resistance and nucleation system ensures thermal stability.

[0051] Comparative Example 1 (without toughening agent): It may have the highest tensile modulus, but its toughness is extremely poor (low elongation at break), making it a brittle material that cannot meet the requirements of complex stress-bearing components.

[0052] Comparative Example 2 (400 rpm high speed): The formulation was the same as in Example 1, but the speed was doubled. Its mechanical properties (especially tensile strength) and dimensional stability were lower than those of Example 1. This is because the high speed caused excessive shearing damage to the glass fiber and POE particles, and may have caused more severe thermal degradation, thus verifying the necessity of the 200 rpm low-speed process for protecting functional components and achieving optimal overall performance.

Claims

1. A high-strength, high-toughness, and high-thermal-stability PA66 composite material, characterized in that... The PA66 composite material, by weight, consists of 50-65 parts PA66 resin, 25-38 parts modified chopped glass fiber, 3-10 parts toughening agent, 0.5-1.5 parts composite heat resistant agent, 0.1-0.6 parts high-efficiency nucleating agent, 0.5-2.0 parts color masterbatch, and 0.2-0.8 parts lubricant.

2. The high-strength, high-toughness, and high-thermal-stability PA66 composite material according to claim 1, characterized in that... The toughening agent is a maleic anhydride-grafted modified polyolefin elastomer.

3. The high-strength, high-toughness, and high-thermal-stability PA66 composite material according to claim 1, characterized in that... The composite heat-resistant agent is composed of a primary antioxidant, an auxiliary antioxidant, and a metal passivator in a weight ratio of 1~2:1~2:0.5~1.

4. The high-strength, high-toughness, and high-thermal-stability PA66 composite material according to claim 3, characterized in that... The primary antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], the secondary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite, and the metal passivator is N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexamethylenediamine.

5. The high-strength, high-toughness, and high-thermal-stability PA66 composite material according to claim 1, characterized in that... The highly efficient nucleating agent is calcium lignite.

6. The high-strength, high-toughness, and high-thermal-stability PA66 composite material according to claim 1, characterized in that... The lubricant is calcium stearate.

7. A method for preparing a high-strength, high-toughness, and high-thermal-stability PA66 composite material according to any one of claims 1-6, characterized in that... The method includes the following steps: Step (1) Premixing: PA66 resin, composite heat resistant agent, high-efficiency nucleating agent, toughening agent, color masterbatch and lubricant are mixed in a high-speed mixer to obtain premix; Step (2) Melt blending and extrusion granulation: The premixed material is added from the main feed port of the twin-screw extruder, and the modified chopped glass fiber is introduced from the side feed port of the twin-screw extruder. The side feed port is located after the melting section of the cylinder and before the vacuum exhaust port. After melt blending and vacuum devolatilization, the material is extruded, cooled, and granulated to obtain composite material particles.

8. The method for preparing the high-strength, high-toughness, and high-thermal-stability PA66 composite material according to claim 7, characterized in that... In step (1), the mixing time is 3 to 5 minutes.

9. The method for preparing the high-strength, high-toughness, and high-thermal-stability PA66 composite material according to claim 7, characterized in that... In step (2), the screw speed of the twin-screw extruder is 180~220 rpm, and the barrel temperature increases gradually from the feed port to the die head in the range of 245℃ to 280℃.

10. The application of a high-strength, high-toughness and high-thermal-stability PA66 composite material as described in any one of claims 1-6 in the manufacture of peripheral structural parts and housings for automobiles and aero-engines.

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