A polyamide resin composition and a method for producing the same

Abstract

The present application provides a kind of polyamide resin composition and preparation method.The polyamide resin composition includes: long carbon chain polyamide resin, MXD6 polyamide resin, long carbon chain polyamide thermoplastic elastomer, high molecular weight maleic anhydride functionalized liquid polybutadiene, plasma surface treatment carbon fiber and optional auxiliary agent.The present application first uses plasma to treat carbon fiber, uses long carbon chain polyamide resin as matrix, simultaneously adds MXD6 polyamide resin, long carbon chain polyamide thermoplastic elastomer and high molecular weight maleic anhydride functionalized liquid polybutadiene, is prepared by twin-screw extrusion granulation rigid excellent, simultaneously has excellent elongation at break and drop hammer impact performance rigid and tough balanced polyamide composition of balance;Such excellent rigid and tough balanced polyamide composition is suitable for sports shoes sole carbon plate and other sports goods related load-bearing components.

Description

Technical Field

[0001] This invention belongs to the field of polyamide resins, and specifically relates to a polyamide resin composition and its preparation method. Background Technology

[0002] Carbon fiber plates in athletic shoes are lightweight, high-strength materials typically embedded in the sole to provide additional support and energy return. Originally developed for high-end running shoes, carbon fiber plates are now widely used in various athletic footwear, including basketball, tennis, and soccer shoes. Currently, carbon fiber plates are carbon fiber-reinforced thermosetting composites, primarily using thermosetting epoxy resins. The main process involves impregnating epoxy resin into carbon fibers and then thermosetting it. However, due to the permanent cross-linking nature of epoxy resin, the increasing use of carbon fiber plates leads to a significant environmental burden from the large number of retired products. Furthermore, the thermosetting process has a significant environmental impact, low molding efficiency, and high manufacturing costs.

[0003] Nylon 12 (PA12 for short) is a common name for polyamide 12, a long-chain nylon polymer and a special high-performance thermoplastic polymer. It possesses high impact strength, low water absorption, good dimensional stability, good toughness and flexibility, and excellent dielectric properties, abrasion resistance, heat resistance, chemical resistance, lubricity, and dyeability. It is mainly used in plastic alloys, automotive manufacturing, aircraft manufacturing, additive manufacturing (3D printing), electronic products, machinery, medical technology, and the oil and gas industry, making it highly irreplaceable. Nylon 12 itself also has good corrosion resistance and abrasion resistance. Carbon fiber reinforcement of PA12 can achieve high strength and high modulus while retaining toughness superior to that of carbon fiber reinforced thermosetting composites.

[0004] Carbon fiber reinforced thermoplastic composites are composite materials composed of a thermoplastic polymer matrix and carbon fiber reinforcement. Carbon fiber is a high-strength, high-modulus fiber material with excellent mechanical properties and lightweight characteristics. Combining carbon fiber with a thermoplastic polymer matrix can yield composite materials with high strength, high stiffness, low weight, certain toughness, and easy recyclability. The mechanical properties of the composite material are significantly affected by the surface treatment of the carbon fiber. Carbon fiber itself has strong inertness, resulting in poor bonding with the matrix material. Surface treatment can improve the surface activity of carbon fiber, strengthen the interfacial properties between carbon fiber and the matrix material, improve its adhesion to the matrix, and thus enhance the mechanical properties of the composite material.

[0005] Chinese invention patent CN103892492A discloses a method for preparing wrinkle-resistant suit fabric, which mainly improves the wrinkle resistance and drape of the woven fabric by treating wool fibers with low-pressure plasma.

[0006] Chinese invention patent CN117325485B discloses a carbon fiber reinforced polyamide composite material for wind turbine blades and its preparation method. This patent involves impregnating carbon fiber cloth with a polyamic acid solution, followed by solvent displacement in water. After displacement, the carbon cloth is removed and dried to obtain polyamic acid-coated carbon fiber cloth. The polyamic acid-coated carbon fiber cloth is then heated and cured, followed by carbonization to obtain modified carbon fiber cloth. Finally, the modified carbon fiber cloth and polyamide sheets are alternately stacked, hot-pressed, and cooled to obtain the final product. This invention constructs an interconnected network within the carbon fiber through in-situ carbonization of polyimide. Due to the stress-guiding effect of the carbon fiber interconnected network, the prepared composite material possesses better mechanical properties.

[0007] Chinese invention patent CN116655964B discloses a high-weather-resistant and high-rigidity polyamide composite material and its preparation process. This patent modifies acyl chloride long-cut carbon fibers sequentially with melamine and vinylphosphonic acid to obtain a modified filler; then, it modifies a semi-aromatic polyamide with mercaptomethacrylate monomer to obtain acrylate-grafted polyamide; finally, it mixes polyamide 410, short-cut carbon fibers, and acrylate-grafted polyamide, performs a single melt extrusion, and pelletizes to obtain raw material A; raw material A, polyamide 6, modified filler, polyvinylpyrrolidone, and benzoyl peroxide are mixed, subjected to a second melt extrusion, and pelletized to obtain the polyamide composite material. Chinese invention patent CN110423462B discloses a carbon fiber reinforced polyamide composite material product and its preparation method. This patent obtains surface-modified carbon fibers through thermoplastic sizing agent treatment, and its carbon fiber reinforced polyamide composite material product is obtained through a single mixing injection molding process.

[0008] Chinese invention patent CN 104845361B discloses a synergistic reinforcement of short-cut carbon fiber, nano-conductive carbon black / graphene, and its preparation method. The invention obtains a thermoplastic with low density, high strength, corrosion resistance, and excellent conductivity by activating the surface of short-cut carbon fiber, nano-conductive carbon black / graphene, and thermoplastic raw materials through in-situ reaction extrusion granulation. Summary of the Invention

[0009] To address the problems existing in the prior art, the present invention provides a polyamide resin composition and its preparation method, resulting in a high-modulus, high-strength carbon fiber reinforced thermoplastic polyamide nylon 12 resin.

[0010] A polyamide resin composition, comprising, by weight parts:

[0011] 40-75 parts of long-chain polyamide resin

[0012] 5-40 parts of plasma-treated carbon fiber

[0013] 10-40 parts of MXD6 polyamide resin

[0014] 4-10 parts of long-chain polyamide thermoplastic elastomer

[0015] 1-5 parts of high molecular weight maleic anhydride functionalized liquid polybutadiene

[0016] 0-3 parts of lubricant

[0017] Antioxidant 0-3 parts.

[0018] In this invention, the average number of carbon atoms Nc of each nitrogen atom in the long carbon chain polyamide resin is between 6 and 18, preferably 9 to 16;

[0019] Preferably, the long-chain polyamide resin includes any one or a combination of at least two of PA612, PA614, PA1012, PA11, PA12, PA1212, PA616 or PA618, with PA12 being the most preferred.

[0020] Preferably, the molar ratio of terminal carboxyl groups to terminal amino groups in the long-chain polyamide resin is 1 to 20, more preferably 3 to 15.

[0021] In this invention, the liquid polybutadiene is functionalized with maleic anhydride, and the maleic anhydride grafting rate is 5%-30%, preferably 5%-15%.

[0022] Preferably, the number-average molecular weight (Mn) of the high molecular weight maleic anhydride-functionalized liquid polybutadiene is greater than 4000 g / mol, more preferably 5000-7000 g / mol;

[0023] Preferably, the viscosity of the high molecular weight maleic anhydride functionalized liquid polybutadiene at 25°C is 1000-4000 dPa·s, and more preferably 1000-2500 dPa·s.

[0024] In this invention, the hard segment of the long-chain polyamide thermoplastic elastomer is an aliphatic long-chain polyamide, and the hard segment is selected from one or more of PA12, PA11, PA1212, PA1010, PA610, PA612, etc., preferably PA12; the soft segment of the long-chain polyamide thermoplastic elastomer is one or more of hydroxyl-terminated polytetrahydrofuran ether, polyethylene glycol, polypropylene glycol, copolyether glycol, polyether diamine, polyester, polycarbonate, polyolefin, polysiloxane, preferably polytetrahydrofuran ether;

[0025] Preferably, the molar ratio of polyamide hard segments to soft segments is 1:0.9 to 1.5;

[0026] In a preferred embodiment, the long-chain polyamide thermoplastic elastomer has a Shore hardness of 35-70D.

[0027] In this invention, the MXD6 polyamide resin is formed by the condensation reaction of MXDA and adipic acid, and the melting point of the resin is preferably 230℃-255℃, and its relative intrinsic viscosity is 2.5-3.8.

[0028] In this invention, the lubricant is one or more of the following: ethylene bis-stearamide, stearamide, oleamide, polyethylene wax, calcium stearate, zinc stearate, liquid, paraffin, and microcrystalline wax; preferably, the lubricant is one or more of the following: polyethylene wax, calcium stearate, and zinc stearate.

[0029] In this invention, the antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants, wherein the hindered phenolic antioxidants are selected from antioxidants 1098, 1010, and 1076, preferably antioxidant 1098; the phosphite antioxidants are selected from antioxidants 168, 626, and 619, preferably antioxidant 168.

[0030] Preferably, the antioxidant is a combination of hindered phenolic antioxidant and phosphite antioxidant in a ratio of 1:0.9-1.2. For example, in a specific embodiment, the mass ratio of hindered phenolic antioxidant to phosphite antioxidant is 1:1.

[0031] In this invention, the carbon fiber in the plasma surface-treated carbon fiber is selected from one or more of polyacrylonitrile-based carbon fiber, petroleum pitch-based carbon fiber, coal pitch-based carbon fiber, viscose-based carbon fiber, phenolic-based carbon fiber, vapor-grown carbon fiber, bacterial cellulose-based carbon fiber, cellulose-based carbon fiber and lignin-based carbon fiber, with polyacrylonitrile-based carbon fiber being preferred.

[0032] Preferably, the carbon fiber comprises one or more of chopped carbon fiber (length 1mm-10mm), long-cut carbon fiber (length 10mm-50mm), and continuous carbon fiber (length > 50mm or continuous fiber), with chopped carbon fiber being the most preferred.

[0033] Preferably, the plasma surface-treated carbon fiber is treated by one or more of atmospheric pressure plasma treatment, low pressure plasma treatment, pulsed plasma treatment, and remote plasma treatment, with low pressure plasma surface treatment being preferred.

[0034] Preferably, the gas used for plasma surface treatment of carbon fibers includes air, oxygen, nitrogen, argon, helium, hydrogen, methane, fluorine, nitrogen / hydrogen, air / hydrogen, air / hydrogen or other gases and gas mixtures, with argon being preferred;

[0035] Preferably, the plasma surface treatment process conditions for carbon fibers are a gas pressure of 50-70 Pa, a glow discharge power of 30-40 W, and a treatment time of 2-3 min.

[0036] A method for preparing a polyamide resin composition includes the following steps:

[0037] Long-chain polyamide resin, MXD6 polyamide resin, long-chain polyamide thermoplastic elastomer, optional lubricant, and optional antioxidant are mixed in proportion. High molecular weight maleic anhydride functionalized liquid polybutadiene is added to a plunger pump connected to the extruder. Plasma-surface-treated carbon fibers are added from the side feed port for extrusion granulation.

[0038] Preferably, before mixing the components, the long-chain polyamide thermoplastic elastomer and the long-chain polyamide resin are dried at 70-90°C for 4-6 hours; the MXD6 polyamide resin is dried at 150-160°C for 4-6 hours until the moisture content is reduced to ≤0.01wt%.

[0039] Preferably, the mixing process conditions include: mixing time of 3-10 min, rotation speed of 20-100 rpm, and temperature of 10-40℃.

[0040] Preferably, the extrusion process conditions include: extruder screw temperature of 210-250℃, more preferably 220-240℃, and screw speed of 200-600rpm, more preferably 220-300rpm.

[0041] The polyamide composition involved in this invention effectively improves the rigidity of nylon materials, approaching the tensile strength and modulus of carbon fiber reinforced thermosetting resins, while maintaining good toughness and improving its impact resistance. It is suitable for replacing thermosetting resin carbon plates in footwear applications and significantly improves production efficiency.

[0042] Compared to existing technologies, this invention has several advantages:

[0043] First, the present invention involves plasma activation treatment of the carbon fiber surface using plasma gas followed by blending and granulation with a polyamide composition. The surface of the carbon fiber after plasma treatment is etched and active groups of carboxyl, carbonyl, and hydroxyl are obtained. At the same time, the excellent flowability of MXD6 polyamide resin is introduced into the composition to increase the wettability of the carbon fiber surface and significantly improve the rigidity of the composition.

[0044] Secondly, the present invention uses long-chain polyamide resin as the matrix, and simultaneously adds long-chain polyamide thermoplastic elastomer and high molecular weight maleic anhydride functionalized liquid polybutadiene, forming an island structure between the fiber reinforcement materials to absorb impact energy, effectively reducing the damage of impact to the fibers, thereby increasing the toughness of the composition, and comprehensively achieving both high rigidity and good rigidity-toughness balance. Detailed Implementation

[0045] To facilitate researchers in the field to better understand the polyamide resin composition, preparation method, and properties prepared by the present invention, the present invention will be further described below with specific examples. However, this is only for further detailed description and is not intended to limit the scope of the present invention.

[0046] The sources of raw materials are shown in Table 1:

[0047] Table 1 Source of Raw Materials

[0048]

[0049] Performance testing shall be conducted in accordance with the standards in Table 2.

[0050] Table 2 Test Methods and Standards

[0051]

[0052] Examples and Comparative Examples

[0053] Preparation method of polyamide resin composition:

[0054] The process utilizes low-pressure plasma treatment in argon plasma gas with a pressure of 50-70 Pa, a glow discharge power of 30-40 W, and a treatment time of 2-3 min.

[0055] Raw materials were weighed according to the proportions in Tables 3 and 4. MXD6 was dried in a vacuum oven at 150℃ for 6 hours until its water content was reduced to ≤0.01wt%. Long-chain polyamide thermoplastic elastomer was dried at 70℃ for 6 hours; PA12 was dried at 90℃ for 4 hours. High molecular weight maleic anhydride functionalized liquid polybutadiene was heated to 50℃ and added to a plunger pump connected to the extruder. Long-chain polyamide resin, long-chain polyamide thermoplastic elastomer, MXD6 polyamide resin, optional antioxidant, and optional lubricant were added to a high-speed mixer and mixed for 5 minutes at 80 rpm and 30℃. The mixture was then fed into the extruder through the main feed port for extrusion granulation. Low-pressure plasma-treated carbon fibers were added through the side feed port for co-extrusion granulation. During extrusion, the extruder screw temperature was 230℃ and the screw speed was 260 rpm.

[0056] The properties of the materials were tested, and the results are shown in Tables 3 and 4.

[0057] Table 3. Examples and their performance tests

[0058]

[0059]

[0060] Table 4 Comparative examples and their performance tests

[0061]

[0062]

[0063] As shown in Tables 3 and 4, Examples 1-6 improve rigidity while maintaining a certain degree of toughness by adding plasma-treated carbon fiber, MXD6 polyamide resin, high molecular weight maleic anhydride-functionalized liquid polybutadiene, and long-chain polyamide thermoplastic elastomer. The polyamide composition provided by this invention possesses excellent rigidity while also exhibiting a good balance of rigidity and toughness with excellent elongation at break and drop-weight impact performance, making it suitable for a wide range of applications.

[0064] Although the invention has been described in detail above for illustrative purposes, it should be understood that such detailed description is merely for illustration, and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention, which is defined only by the claims.

Claims

1. A polyamide resin composition, comprising, by weight parts: 40-75 parts of long-chain polyamide resin Plasma surface treatment of carbon fibers, 5-40 parts. 10-40 parts of MXD6 polyamide resin, 4-10 parts of long-chain polyamide thermoplastic elastomer 1-5 parts of high molecular weight maleic anhydride-functionalized liquid polybutadiene. Lubricant 0-3 parts, Antioxidant 0-3 parts.

2. The polyamide resin composition according to claim 1, characterized in that, The long-chain polyamide resin has an average number of carbon atoms Nc per nitrogen atom of 6-18.

3. The polyamide resin composition according to claim 1, characterized in that, The long-chain polyamide resin includes any one or a combination of at least two of PA612, PA614, PA1012, PA11, PA12, PA1212, PA616, or PA618.

4. The polyamide resin composition according to claim 1, characterized in that, The molar ratio of terminal carboxyl groups to terminal amino groups in long-chain polyamide resins is 1 to 20.

5. The polyamide resin composition according to claim 3, characterized in that, The molar ratio of terminal carboxyl groups to terminal amino groups in long-chain polyamide resins is 3 to 15.

6. The polyamide resin composition according to claim 1, characterized in that, The number-average molecular weight of high molecular weight maleic anhydride-functionalized liquid polybutadiene is greater than 4000 g / mol.

7. The polyamide resin composition according to claim 6, characterized in that, The number-average molecular weight of high molecular weight maleic anhydride-functionalized liquid polybutadiene is 5000-7000 g / mol.

8. The polyamide resin composition according to claim 6 or 7, characterized in that, The grafting rate of maleic anhydride is 5%-30%.

9. The polyamide resin composition according to claim 8, characterized in that, The grafting rate of maleic anhydride is 5%-15%.

10. The polyamide resin composition according to claim 6 or 7, characterized in that, High molecular weight maleic anhydride functionalized liquid polybutadiene has a viscosity of 1000-4000 dPa·s at 25°C.

11. The polyamide resin composition according to claim 10, characterized in that, The viscosity of high molecular weight maleic anhydride-functionalized liquid polybutadiene is 1000-2500 dPa·s at 25℃.

12. The polyamide resin composition according to claim 1, characterized in that, The hard segment of the long-chain polyamide thermoplastic elastomer is an aliphatic long-chain polyamide, which is one or more of PA12, PA11, PA1212, PA1010, PA610, and PA612. The soft segment of the long-chain polyamide thermoplastic elastomer is one or more of hydroxyl-terminated polytetrahydrofuran ether, polyethylene glycol, polypropylene glycol, copolyether diol, polyether diamine, polyester, polycarbonate, polyolefin, and polysiloxane.

13. The polyamide resin composition according to claim 12, characterized in that, The molar ratio of hard segments to soft segments is 1:0.9 to 1.

5.

14. The polyamide resin composition according to claim 1, characterized in that, MXD6 polyamide resin is produced by the polycondensation reaction of MXDA and adipic acid. The melting point of MXD6 polyamide resin is 230℃-255℃, and its relative intrinsic viscosity is 2.5~3.

8.

15. The polyamide resin composition according to claim 1, characterized in that, The carbon fibers used in plasma surface-treated carbon fibers are selected from one or more of the following: polyacrylonitrile-based carbon fibers, petroleum pitch-based carbon fibers, coal tar pitch-based carbon fibers, viscose-based carbon fibers, phenolic-based carbon fibers, vapor-grown carbon fibers, bacterial cellulose-based carbon fibers, and lignin-based carbon fibers.

16. The polyamide resin composition according to claim 15, characterized in that, The carbon fiber is selected from one or more of chopped carbon fiber, long-cut carbon fiber, and continuous carbon fiber.

17. The polyamide resin composition according to claim 1 or 15, characterized in that, The plasma surface treatment method is selected from one or more of atmospheric pressure plasma treatment, low pressure plasma treatment, pulsed plasma treatment, and remote plasma treatment.

18. The polyamide resin composition according to claim 17, characterized in that, The process conditions for low-pressure plasma treatment are: plasma gas pressure of 50-70 Pa, glow discharge power of 30-40 W, and treatment time of 2-3 min.

19. The polyamide resin composition according to claim 1, characterized in that, The lubricant is one or more of the following: ethylene bis-stearamide, stearamide, oleamide, polyethylene wax, calcium stearate, zinc stearate, liquid paraffin, and microcrystalline wax; And / or: The antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants, wherein the hindered phenolic antioxidants are selected from antioxidants 1098, 1010, and 1076, and the phosphite antioxidants are selected from antioxidants 168, 626, and 619.

20. A method for preparing the polyamide resin composition according to any one of claims 1-19, characterized in that, Includes the following steps: Long-chain polyamide resin, MXD6 polyamide resin, long-chain polyamide thermoplastic elastomer, optional lubricant, and optional antioxidant are mixed in proportion. High molecular weight maleic anhydride functionalized liquid polybutadiene is added to a plunger pump connected to the extruder. Plasma-surface-treated carbon fibers are added from the side feed port for extrusion granulation.

21. The preparation method according to claim 20, characterized in that, The extruder screw temperature is 210-250℃, and the screw speed is 200-600rpm.

22. The preparation method according to claim 21, characterized in that, The extruder screw temperature is 220-240℃, and the screw speed is 220-300rpm.

23. The preparation method according to claim 20, characterized in that, Before mixing the raw materials, the MXD6 polyamide resin is dried at 150-160℃ for 4-6 hours until the moisture content drops to ≤0.01wt%.

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