High-wear-resistance and high-heat-resistance polyamide modified fiber composite material and preparation method thereof

Abstract

The invention provides a high-wear-resistance and high-heat-resistance polyamide modified fiber composite material and a preparation method thereof, and relates to the technical field of high polymer materials and composite modification.The preparation method comprises the steps that polytetrafluoroethylene and graphite are metered, and the mass ratio of the polytetrafluoroethylene to the graphite is 1: 1; the wear-resistant and heat-resistant functional additive premix is prepared by premixing polytetrafluoroethylene / graphite, a flaky inorganic filler, nano silicon dioxide and other wear-resistant and heat-resistant components, and then premixing the wear-resistant and heat-resistant functional additive premix with hexagonal boron nitride, the flaky inorganic filler and nano silicon dioxide, so as to obtain the wear-resistant and heat-resistant functional additive premix. The multi-phase functional filler is introduced and fully dispersed in sections in the twin-screw melt blending process, so that the multi-phase functional filler forms a uniform and stable composite system in a polyamide matrix, the wear resistance and heat resistance of the material are synergistically improved, and the service stability and consistency under the working condition of high-temperature friction are improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and their composite modification technology, specifically to a high wear-resistant and high heat-resistant polyamide modified fiber composite material and its preparation method. Background Technology

[0002] In existing technologies, polyamide materials are widely used in load-bearing and friction components such as gears, bushings, sliding bearings, and guide parts due to their good mechanical properties, chemical resistance, and processability. To improve their load-bearing capacity and dimensional stability, glass fiber, carbon fiber, aramid fiber, etc., are usually used for reinforcement, and inorganic fillers or solid lubricants are added to modify the material's wear resistance, friction characteristics, and heat distortion properties. At the same time, compatibilizers, coupling agents, or interface treatments are used to improve the bonding between the fibers and the polyamide matrix to obtain more stable overall performance.

[0003] However, under conditions of high speed, high load and significant frictional heat generation, existing polyamide fiber composite materials still cannot simultaneously achieve high wear resistance and high heat resistance: polyamide is prone to softening at higher temperatures and creep increases and thermo-oxidative aging, leading to increased wear and decreased fit accuracy; fiber-reinforced systems are prone to fiber exposure, pull-out and interface peeling during wear, causing fluctuations in the coefficient of friction and potentially exacerbating wear on mating parts. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high wear-resistant and high heat-resistant polyamide modified fiber composite material and its preparation method. The technical problem to be solved by this invention is: how to solve the problems of increased wear of polyamide under high speed and high load frictional heat generation, as well as frictional fluctuations caused by fiber exposure, pull-out and interface peeling, through a segmented feeding melt blending preparation process combined with wear-resistant and heat-resistant synergistic modification and interface reinforcement.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high wear-resistant and high heat-resistant polyamide-modified fiber composite material, comprising, by weight percentage: Polyamide matrix resin 52%-66%; Short-cut glass fiber 24%-28%; Polytetrafluoroethylene 1%-2%; Graphite 1%-2%; Hexagonal boron nitride 3%-5.5%; The flaky inorganic filler is 3.5%-6%, and the flaky inorganic filler is mica powder or talc powder; Nano-silica 0.8%-1.8%; 0.6%-1.2% of a reactive compatibilizer containing epoxy groups, wherein the reactive compatibilizer is an ethylene-acrylate-glycidyl methacrylate terpolymer or a styrene-acrylate copolymer containing epoxy groups; γ-aminopropyltriethoxysilane 0.15%-0.45%; The hindered phenolic antioxidant is 0.15%-0.3%, wherein the hindered phenolic antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]; The antioxidant phosphite is 0.05%-0.12%, wherein the antioxidant phosphite is tris(2,4-di-tert-butylphenyl) phosphite; Cuprous iodide 0.02%-0.05%; Potassium iodide 0.04%-0.1%; Polyethylene wax 0.1%-0.25%.

[0006] The present invention is further configured such that the polyamide matrix resin is composed of polyamide 66 and semi-aromatic polyamide, wherein the mass percentage of polyamide 66 is 34%-44% and the mass percentage of semi-aromatic polyamide is 18%-22%; the semi-aromatic polyamide is any one of PA6T / 66, PA6T / 6I or PA9T.

[0007] The present invention is further configured such that the chopped glass fiber is glass fiber treated with silane sizing.

[0008] The present invention is further configured such that the mass ratio of the polytetrafluoroethylene to the graphite is 1:1.

[0009] A method for preparing a high-wear-resistant and high-heat-resistant polyamide-modified fiber composite material, comprising: S1. Provides a polyamide matrix resin, chopped glass fiber, polytetrafluoroethylene, graphite, hexagonal boron nitride, sheet-like inorganic filler, nano-silica, a reactive compatibilizer containing epoxy groups, γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax; the polyamide matrix resin is dried to meet the moisture content requirements for melt blending; S2. The polytetrafluoroethylene and the graphite are metered and their mass ratio is 1:1. Then, they are premixed with the hexagonal boron nitride, the sheet-like inorganic filler and the nano-silica to obtain a wear-resistant and heat-resistant functional additive premix. S3. The dried polyamide matrix resin and the reactive compatibilizer containing epoxy groups are fed into the main feed port of a twin-screw extruder for melt plasticization. The wear-resistant and heat-resistant functional additive premix is ​​added and dispersed through the side feed port. The γ-aminopropyltriethoxysilane, the hindered phenolic antioxidant, the phosphite antioxidant, the cuprous iodide, the potassium iodide, and the polyethylene wax are added to the melt and mixed. In the downstream mixing section of the extruder, the chopped glass fibers are added through the side feed port to obtain a mixed melt. The epoxy groups of the reactive compatibilizer react with the polyamide matrix resin, and the γ-aminopropyltriethoxysilane couples and reinforces the glass fiber / polyamide interface to suppress fiber exposure, pull-out, and interface peeling during the wear process. S4. After vacuum devolatilization of the compounded melt, it is extruded into strips, cooled, and pelletized to obtain composite material granules; S5. Cool, screen and package the composite material granules to obtain the finished composite material.

[0010] The present invention is further configured such that, after the polyamide matrix resin is dried, the moisture content is not greater than 0.10 wt%; the moisture content is determined by Karl Fischer method.

[0011] The present invention is further configured such that the premixing is performed by a mixer with a speed of 800 r / min-1200 r / min and a mixing time of 3 min-8 min; and the polytetrafluoroethylene, graphite, hexagonal boron nitride, sheet-like inorganic filler, and nano-silica are added to the mixer in the order of addition to obtain the wear-resistant and heat-resistant functional additive premix.

[0012] The present invention is further configured such that the length-to-diameter ratio of the screw of the twin-screw extruder is 40-48, the set temperature of each temperature zone of the twin-screw extruder is 250℃-290℃, and the screw speed is 200r / min-350r / min.

[0013] The present invention is further configured such that the γ-aminopropyltriethoxysilane, the hindered phenolic antioxidant, the phosphite antioxidant, the cuprous iodide, and the potassium iodide are added to the melt and mixed before the chopped glass fibers are added, and the chopped glass fibers are added through a side feed port located at 0.65 to 0.80 times the effective length of the screw, in order to reduce the shear breakage of the chopped glass fibers during the mixing process and enhance the interfacial bonding of the glass fiber / polyamide.

[0014] The present invention is further configured such that the absolute pressure corresponding to the vacuum degree of the vacuum devolatilization is 5kPa-15kPa; after extrusion into strips, water cooling is used for cooling, the temperature of the cooling medium is 15℃-30℃, and the finished composite material is sealed and packaged using moisture-proof packaging material.

[0015] The beneficial effects of this invention are as follows: This invention premixes wear-resistant and heat-resistant components such as polytetrafluoroethylene / graphite, hexagonal boron nitride, sheet-like inorganic fillers, and nano-silica, and introduces and fully disperses them in stages during the twin-screw melt blending process, so that the multiphase functional fillers form a uniform and stable composite system in the polyamide matrix, thereby achieving a synergistic improvement in the wear resistance and heat resistance of the material, and improving the service stability and consistency under high-temperature friction conditions.

[0016] This invention employs a synergistic interfacial enhancement mechanism between a reactive compatibilizer containing epoxy groups and γ-aminopropyltriethoxysilane, combined with the feeding method of chopped glass fibers downstream of the extruder, to enhance the interfacial bonding of glass fiber / polyamide and reduce shear damage to fibers during processing. This effectively suppresses fiber exposure, pull-out, and interfacial peeling during the wear process, thereby further improving wear resistance and heat resistance while ensuring mechanical strength. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0018] Figure 1 This is a schematic diagram of the composite material composition of the present invention.

[0019] Figure 2 This is a schematic diagram showing the composition and proportion of the polyamide matrix resin of the present invention.

[0020] Figure 3 This is a flow chart of the premixing process for the wear-resistant and heat-resistant functional additives of this invention.

[0021] Figure 4 The figure shows a process flow diagram for the preparation of composite materials according to the present invention.

[0022] Figure 5 This is a schematic diagram of the feeding and mixing process of a twin-screw extruder according to the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Example 1

[0025] Please see Figures 1-5 This invention relates to a high-wear-resistant and high-heat-resistant polyamide-modified fiber composite material, comprising, by weight percentage: The polyamide matrix resin comprises 65.59%. The polyamide matrix resin is composed of polyamide 66 and semi-aromatic polyamide, with polyamide 66 accounting for 44% by mass and the semi-aromatic polyamide accounting for 21.59% by mass. The semi-aromatic polyamide is PA6T / 66.

[0026] 24% chopped glass fiber. The chopped glass fiber is glass fiber that has been sizing with silane.

[0027] 1% polytetrafluoroethylene.

[0028] Graphite 1%. The mass ratio of polytetrafluoroethylene to graphite is 1:1.

[0029] 3% hexagonal boron nitride.

[0030] The flaky inorganic filler accounts for 3.5%, and the flaky inorganic filler is mica powder.

[0031] Nano-silica 0.8%.

[0032] The reactive compatibilizer containing epoxy groups is 0.6%, and the reactive compatibilizer is a terpolymer of ethylene-acrylate-glycidyl methacrylate.

[0033] 0.15% γ-aminopropyltriethoxysilane.

[0034] The hindered phenolic antioxidant is 0.15%, and the hindered phenolic antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid].

[0035] The antioxidant phosphite is 0.05%, and the antioxidant phosphite is tris(2,4-di-tert-butylphenyl) phosphite.

[0036] Cuprous iodide 0.02%.

[0037] Potassium iodide 0.04%.

[0038] Polyethylene wax 0.1%.

[0039] A method for preparing a high-wear-resistant and high-heat-resistant polyamide-modified fiber composite material, comprising: S1. Provides a polyamide matrix resin, chopped glass fiber, polytetrafluoroethylene, graphite, hexagonal boron nitride, flake inorganic filler, nano-silica, reactive compatibilizer containing epoxy groups, γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax. The polyamide matrix resin is dried to meet the moisture content requirements for melt blending. After drying, the moisture content of the polyamide matrix resin is no more than 0.10 wt%. The moisture content is determined by the Karl Fischer method.

[0040] S2. Polytetrafluoroethylene (PTFE) and graphite are metered to a mass ratio of 1:1, and then premixed with hexagonal boron nitride, flake-shaped inorganic filler, and nano-silica to obtain a premix of wear-resistant and heat-resistant functional additives. Premixing is performed using a mixer at a speed of 800 r / min for 3 min. PTFE, graphite, hexagonal boron nitride, flake-shaped inorganic filler, and nano-silica are added to the mixer in the following order to obtain the wear-resistant and heat-resistant functional additive premix.

[0041] S3. The dried polyamide matrix resin and a reactive compatibilizer containing epoxy groups are melted and plasticized at the main feed port of a twin-screw extruder. A wear-resistant and heat-resistant functional additive premix is ​​added and dispersed through the side feed port. γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax are added to the melt and mixed. Short-cut glass fibers are added through the side feed port in the downstream mixing section of the extruder to obtain a mixed melt. This allows the epoxy groups of the reactive compatibilizer to react with the polyamide matrix resin, and γ-aminopropyltriethoxysilane to couple and reinforce the glass fiber / polyamide interface, inhibiting fiber exposure, pull-out, and interfacial delamination during the wear process. The twin-screw extruder has a screw length-to-diameter ratio of 40, a set temperature of 250°C for each temperature zone, and a screw speed of 200 r / min. γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide and potassium iodide are added to the melt and mixed before the chopped glass fibers are added. The chopped glass fibers are added through a side feed port located at 0.65 times the effective length of the screw to reduce shear breakage of the chopped glass fibers during the mixing process and enhance the interfacial bonding of glass fiber / polyamide.

[0042] S4. After vacuum devolatilization of the compounded melt, it is extruded into strips, cooled, and pelletized to obtain composite material granules. The absolute pressure corresponding to the vacuum degree of vacuum devolatilization is 5 kPa. After extrusion, the strips are cooled by water cooling at a temperature of 15°C. The finished composite material is sealed in moisture-proof packaging material.

[0043] S5. Cool, screen and package the composite material granules to obtain the finished composite material.

[0044] Even with relatively low levels of component content and process conditions, the system can still form a stable polyamide matrix reinforcement structure. The glass fiber and polyamide matrix establish a relatively stable interfacial bond through reactive compatibility and silane coupling. At the same time, the wear-resistant filler and solid lubricant components form a basic synergistic effect within the material, enabling the material to maintain good processing fluidity while possessing certain wear resistance and heat stability. This indicates that the performance of composite materials can still be effectively improved at low addition levels.

[0045] Example 2 Please see Figures 1-5 Based on Example 1, a high wear-resistant and high heat-resistant polyamide modified fiber composite material, by weight percentage, comprises: The polyamide matrix resin comprises 58.89%. The polyamide matrix resin is composed of polyamide 66 and semi-aromatic polyamide, with polyamide 66 accounting for 38.89% by mass and the semi-aromatic polyamide accounting for 20% by mass. The semi-aromatic polyamide is PA6T / 66.

[0046] 26% chopped glass fiber. The chopped glass fiber is glass fiber that has been sized with silane.

[0047] Polytetrafluoroethylene 1.5%.

[0048] Graphite 1.5%. The mass ratio of polytetrafluoroethylene to graphite is 1:1.

[0049] Hexagonal boron nitride 4.25%.

[0050] The flaky inorganic filler comprises 4.75%, and the flaky inorganic filler is mica powder.

[0051] Nano-silica 1.3%.

[0052] The reactive compatibilizer containing epoxy groups is 0.9%, and the reactive compatibilizer is a terpolymer of ethylene-acrylate-glycidyl methacrylate.

[0053] 0.3% γ-aminopropyltriethoxysilane.

[0054] The hindered phenolic antioxidant is 0.23%, and the hindered phenolic antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid].

[0055] The antioxidant phosphite is 0.09%, and the antioxidant phosphite is tris(2,4-di-tert-butylphenyl) phosphite.

[0056] Cuprous iodide 0.04%.

[0057] Potassium iodide 0.07%.

[0058] Polyethylene wax 0.18%.

[0059] A method for preparing a high-wear-resistant and high-heat-resistant polyamide-modified fiber composite material, comprising: S1. Provides a polyamide matrix resin, chopped glass fiber, polytetrafluoroethylene, graphite, hexagonal boron nitride, flake inorganic filler, nano-silica, reactive compatibilizer containing epoxy groups, γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax. The polyamide matrix resin is dried to meet the moisture content requirements for melt blending. After drying, the moisture content of the polyamide matrix resin is no more than 0.10 wt%. The moisture content is determined by the Karl Fischer method.

[0060] S2. Polytetrafluoroethylene (PTFE) and graphite are metered to a mass ratio of 1:1, and then premixed with hexagonal boron nitride, flake-shaped inorganic filler, and nano-silica to obtain a premix of wear-resistant and heat-resistant functional additives. Premixing is performed using a mixer at a speed of 1000 r / min for 5.5 min. PTFE, graphite, hexagonal boron nitride, flake-shaped inorganic filler, and nano-silica are added to the mixer in the following order to obtain the wear-resistant and heat-resistant functional additive premix.

[0061] S3. The dried polyamide matrix resin and a reactive compatibilizer containing epoxy groups are melted and plasticized at the main feed port of a twin-screw extruder. A wear-resistant and heat-resistant functional additive premix is ​​added and dispersed through the side feed port. γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax are added to the melt and mixed. Short-cut glass fibers are added through the side feed port in the downstream mixing section of the extruder to obtain a mixed melt. This allows the epoxy groups of the reactive compatibilizer to react with the polyamide matrix resin, and γ-aminopropyltriethoxysilane to couple and reinforce the glass fiber / polyamide interface, inhibiting fiber exposure, pull-out, and interfacial delamination during the wear process. The twin-screw extruder has a screw length-to-diameter ratio of 44, a set temperature of 270°C for each temperature zone, and a screw speed of 275 r / min. γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide and potassium iodide are added to the melt and mixed before the chopped glass fibers are added. The chopped glass fibers are added through a side feed port located at 0.73 times the effective length of the screw to reduce shear breakage of the chopped glass fibers during the mixing process and enhance the interfacial bonding of glass fiber / polyamide.

[0062] S4. After vacuum devolatilization of the compounded melt, it is extruded into strips, cooled, and pelletized to obtain composite material granules. The absolute pressure corresponding to the vacuum degree of vacuum devolatilization is 10 kPa. After extrusion, the strips are cooled by water cooling at a temperature of 17.5℃. The finished composite material is sealed in moisture-proof packaging material.

[0063] S5. Cool, screen and package the composite material granules to obtain the finished composite material.

[0064] When the functional components are in the middle ratio range, a more balanced synergistic structure is formed between the reinforcing phase, the lubricating phase and the heat-resistant filler, which ensures the mechanical support provided by the glass fiber reinforcement. Through the synergistic dispersion of various wear-resistant and heat-resistant fillers in the matrix, a stable functional network structure can be constructed, thereby achieving a good comprehensive balance between material strength, wear resistance and heat resistance stability, and exhibiting relatively stable and excellent overall performance.

[0065] Example 3 Please see Figures 1-5 Based on Examples 1 and 2, a high-wear-resistant and high-heat-resistant polyamide modified fiber composite material, by weight percentage, comprises: The polyamide matrix resin comprises 52.23%. The polyamide matrix resin is composed of polyamide 66 and semi-aromatic polyamide, with polyamide 66 accounting for 34% by mass and the semi-aromatic polyamide accounting for 18.23% by mass. The semi-aromatic polyamide is PA6T / 66.

[0066] 28% chopped glass fiber. The chopped glass fiber is glass fiber that has been sized with silane.

[0067] 2% polytetrafluoroethylene.

[0068] Graphite 2%. The mass ratio of polytetrafluoroethylene to graphite is 1:1.

[0069] Hexagonal boron nitride 5.5%.

[0070] The flaky inorganic filler accounts for 6%, and the flaky inorganic filler is mica powder.

[0071] Nano-silica 1.8%.

[0072] The reactive compatibilizer containing epoxy groups is 1.2%, and the reactive compatibilizer is an ethylene-acrylate-glycidyl methacrylate terpolymer.

[0073] 0.45% γ-aminopropyltriethoxysilane.

[0074] The hindered phenolic antioxidant is 0.3%, and the hindered phenolic antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid].

[0075] The antioxidant is 0.12% phosphite, and the antioxidant is tris(2,4-di-tert-butylphenyl) phosphite.

[0076] Cuprous iodide 0.05%.

[0077] Potassium iodide 0.1%.

[0078] Polyethylene wax 0.25%.

[0079] A method for preparing a high-wear-resistant and high-heat-resistant polyamide-modified fiber composite material, comprising: S1. Provides a polyamide matrix resin, chopped glass fiber, polytetrafluoroethylene, graphite, hexagonal boron nitride, flake inorganic filler, nano-silica, reactive compatibilizer containing epoxy groups, γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax. The polyamide matrix resin is dried to meet the moisture content requirements for melt blending. After drying, the moisture content of the polyamide matrix resin is no more than 0.10 wt%. The moisture content is determined by the Karl Fischer method.

[0080] S2. Polytetrafluoroethylene (PTFE) and graphite are metered to a mass ratio of 1:1, and then premixed with hexagonal boron nitride, flake-shaped inorganic filler, and nano-silica to obtain a premix of wear-resistant and heat-resistant functional additives. Premixing is performed using a mixer at a speed of 1200 r / min for 8 min. PTFE, graphite, hexagonal boron nitride, flake-shaped inorganic filler, and nano-silica are added to the mixer in the following order to obtain the wear-resistant and heat-resistant functional additive premix.

[0081] S3. The dried polyamide matrix resin and a reactive compatibilizer containing epoxy groups are melted and plasticized at the main feed port of a twin-screw extruder. A wear-resistant and heat-resistant functional additive premix is ​​added and dispersed through the side feed port. γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax are added to the melt and mixed. Short-cut glass fibers are added through the side feed port in the downstream mixing section of the extruder to obtain a mixed melt. This allows the epoxy groups of the reactive compatibilizer to react with the polyamide matrix resin, and γ-aminopropyltriethoxysilane to couple and reinforce the glass fiber / polyamide interface, inhibiting fiber exposure, pull-out, and interfacial delamination during the wear process. The twin-screw extruder has a screw length-to-diameter ratio of 48, a set temperature of 290℃ for each temperature zone, and a screw speed of 350 r / min. γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide and potassium iodide are added to the melt and mixed before the chopped glass fibers are added. The chopped glass fibers are added through a side feed port located at 0.80 times the effective length of the screw to reduce shear breakage of the chopped glass fibers during the mixing process and enhance the interfacial bonding of glass fiber / polyamide.

[0082] S4. After vacuum devolatilization of the compounded melt, it is extruded into strips, cooled, and pelletized to obtain composite material granules. The absolute pressure corresponding to the vacuum degree of vacuum devolatilization is 15 kPa. After extrusion, the strips are cooled by water cooling at a temperature of 30°C. The finished composite material is sealed in moisture-proof packaging material.

[0083] S5. Cool, screen and package the composite material granules to obtain the finished composite material.

[0084] When the content of each component and the processing parameters are at a high level, the content of reinforcing phase and functional filler in the system further increases. Various wear-resistant and heat-resistant fillers form a more obvious synergistic reinforcement and wear-resistant structure in the matrix. At the same time, through the interfacial reinforcement effect of reactive compatibilizers and coupling agents, a stronger interfacial bond is formed between glass fiber and polyamide matrix, thereby further improving the wear resistance and heat resistance stability of the material, and enhancing the structural stability of the material under high load or high temperature environment.

[0085] Example 4 This embodiment is used to evaluate the influence of changes in the formulation and process parameters of the present invention on the wear resistance, heat resistance, and mechanical properties of polyamide-modified fiber composites. Examples 1, 2, and 3 are designated as Experiment A, Experiment B, and Experiment C, respectively.

[0086] 1. Raw material preparation and drying control Weigh out the following components according to the formulas for Experiment A, Experiment B, and Experiment C: polyamide matrix resin, chopped glass fiber, polytetrafluoroethylene, graphite, hexagonal boron nitride, sheet-like inorganic filler, nano-silica, reactive compatibilizer containing epoxy groups, γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax.

[0087] The polyamide matrix resins in all three experiments were first dried, and the moisture content after drying was controlled to be no more than 0.10 wt%. The Karl Fischer method was used to determine the moisture content to eliminate the influence of moisture differences on melt blending and interfacial reactions.

[0088] Recipe settings: Experiment A used a combination with higher values ​​at the resin end and lower values ​​at the reinforcing and wear-resistant / heat-resistant functional components. Experiment B used a combination where each component was in the middle of the range. Experiment C used a combination with lower values ​​at the resin end and higher values ​​at the glass fiber and wear-resistant / heat-resistant functional components, forming a stepped comparison of the three values.

[0089] The specific weighing ratios for the three formulations shall be performed according to the values ​​listed in the claims of Experiment A, Experiment B, and Experiment C, respectively.

[0090] 2. Premixed wear-resistant and heat-resistant functional additives First, polytetrafluoroethylene and graphite are weighed in a 1:1 ratio and put into a mixer. Then, hexagonal boron nitride, flake inorganic filler and nano silica are added in sequence to prepare a wear-resistant and heat-resistant functional additive premix.

[0091] Experiment A used a mixer with a speed of 800 r / min and a mixing time of 3 min; Experiment B used a mixer with a speed of 1000 r / min and a mixing time of 5.5 min; Experiment C used a mixer with a speed of 1200 r / min and a mixing time of 8 min.

[0092] After premixing, visual inspection and sieving were performed on the three groups of premixed materials to check for obvious agglomeration and stratification, and the differences in mixing uniformity were recorded.

[0093] As the values ​​of the functional filler system gradually increase from ABC, it is more beneficial to increase the mixing intensity and mixing time to obtain a stable premixed dispersion state.

[0094] 3. Twin-screw melt blending and interface construction The dried polyamide matrix resin and reactive compatibilizer are added to the main feed port of the twin-screw extruder for melt plasticization.

[0095] The obtained premix is ​​added and dispersed through a side feed port, followed by the addition of γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide and polyethylene wax for mixing. Short glass fibers are then added through a side feed port in the mixing section downstream of the extruder to obtain the mixed melt.

[0096] The reactive compatibilizer's epoxy groups and the polyamide matrix were reactively compatible, and the coupling reinforcement of the glass fiber / polyamide interface by silane was achieved to suppress fiber exposure, pull-out, and interface delamination during the wear process.

[0097] To reflect the differences in process matching under the three value settings, the three sets of extrusion parameters are set as follows: Experiment A: Screw length-to-diameter ratio 40, temperature set at 250℃ for each zone, screw speed 200r / min; glass fiber was added at the side feed port at 0.65 times the effective length of the screw.

[0098] Experiment B: Screw length-to-diameter ratio 44, temperature set at 270℃ for each zone, screw speed 275r / min; glass fiber was side-fed at 0.73 times the effective length of the screw.

[0099] Experiment C: Screw length-to-diameter ratio 48, temperature set at 290℃ for each temperature zone, screw speed 350r / min; glass fiber was side-fed at 0.80 times the effective length of the screw.

[0100] In the three continuous and stable extrusion stages, the main machine torque, die head pressure, melt appearance and strip surface condition were recorded respectively, and samples were retained at the same sampling frequency.

[0101] As the values ​​of the reinforcing phase and the wear-resistant and heat-resistant functional components are increased from ABC, the process parameters are correspondingly increased, including the screw length-to-diameter ratio, the temperature zone, and the screw speed. At the same time, the glass fiber side feeding point is moved backward to reduce the risk of glass fiber breakage in the high-shear zone and enhance the interfacial bonding stability while ensuring dispersion and mixing.

[0102] 4. Vacuum devolatilization, cooling pelletizing and packaging All three groups of compounded melts were vacuum devoured, extruded into strips, water-cooled, and pelletized to obtain composite material granules: Experiment A: Vacuum devouring absolute pressure 5 kPa, cooling medium temperature 15℃; Experiment B: Vacuum devouring absolute pressure 10 kPa, cooling medium temperature 17.5℃; Experiment C: Vacuum devouring absolute pressure 15 kPa, cooling medium temperature 30℃.

[0103] After pelleting, the pellets are cooled, screened, and sealed for moisture-proof packaging. All three operations are kept consistent to avoid differences in post-processing that could introduce comparative bias.

[0104] 5. Performance Testing and Comparative Evaluation To evaluate the differences in the overall performance of the three groups of experimental samples, standard test specimens were prepared from the composite material granules obtained from Experiments A, B, and C on the same injection molding machine. After molding, the specimens were conditioned in a standard laboratory environment to ensure that the specimens were in a uniform state before performance testing was carried out.

[0105] Wear resistance test: The test was conducted using a pin-disc friction and wear tester.

[0106] During the test, the prepared sample is processed into a sample block of specified size and formed a friction pair with a standard steel disc. The friction and wear test is carried out under constant load and constant speed conditions.

[0107] After the test, the mass difference of the sample before and after the test was measured by electronic balance, and the wear amount and volume wear rate of the material were calculated. At the same time, the average friction coefficient during the friction process was recorded to evaluate the differences in wear resistance of the three groups of materials.

[0108] Mechanical property testing: Tensile properties were determined according to the standard for testing tensile properties of plastics. The test was conducted on an electronic universal testing machine, and the tensile strength and elongation at break of the material were recorded.

[0109] The bending performance was determined according to the plastic bending performance test standard, and the bending strength and bending modulus of the material were obtained by three-point bending.

[0110] Impact performance was tested using a cantilever beam impact testing machine. Notched specimens were subjected to impact tests, and the impact strength of the materials was recorded to evaluate the toughness differences of materials with different proportions.

[0111] Heat resistance test: evaluated by heat distortion temperature test.

[0112] The sample is placed in a heat distortion temperature tester, and a specified load is applied under constant temperature conditions. The temperature at which the sample produces a specified deformation is recorded. The corresponding temperature is used as the heat distortion temperature of the material to reflect the structural stability of the material in a high-temperature environment.

[0113] The performance of samples from three groups (Experiment A, Experiment B, and Experiment C) was tested and compared using the above testing methods. The test results show that all three groups of materials exhibit good wear resistance, mechanical properties, and heat resistance; however, as the formulation values ​​and processing parameters gradually increase, the material properties show certain differences.

[0114] Among them, Experiment A corresponds to the lower values ​​of the formula and process parameters. While ensuring the stability of the material molding, it can form a uniform composite structure. The material has good comprehensive mechanical properties, but the improvement in wear resistance and heat resistance is relatively limited.

[0115] Experiment B corresponds to the intermediate values ​​of the formulation and process parameters. The dispersion of each functional filler in the matrix is ​​more uniform, and the interfacial bonding between glass fiber and polyamide matrix is ​​more stable, resulting in a more balanced overall performance of the material in terms of wear resistance, heat resistance and mechanical properties.

[0116] Experiment C corresponds to higher values ​​of formulation and process parameters. The content of wear-resistant filler and reinforcing components in the system is further increased. Combined with stronger mixing and dispersion conditions, the composite system forms more obvious wear-resistant and heat-resistant structural characteristics, showing more outstanding effects in terms of wear resistance and heat resistance stability. However, the material processing stability and the degree of balance of comprehensive performance are slightly different compared with Experiment B.

[0117] In summary, the comparison shows that, within the formulation range and process conditions defined by this invention, different values ​​can all be used to prepare polyamide modified fiber composite materials with good wear resistance and heat resistance. Among them, the material exhibits more balanced overall performance under the intermediate value conditions.

[0118] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high-wear-resistant and high-heat-resistant polyamide-modified fiber composite material, characterized in that, By weight percentage, including: Polyamide matrix resin 52%-66%; Short-cut glass fiber 24%-28%; Polytetrafluoroethylene 1%-2%; Graphite 1%-2%; Hexagonal boron nitride 3%-5.5%; The flaky inorganic filler is 3.5%-6%, and the flaky inorganic filler is mica powder or talc powder; Nano-silica 0.8%-1.8%; 0.6%-1.2% of a reactive compatibilizer containing epoxy groups, wherein the reactive compatibilizer is an ethylene-acrylate-glycidyl methacrylate terpolymer or a styrene-acrylate copolymer containing epoxy groups; γ-aminopropyltriethoxysilane 0.15%-0.45%; The hindered phenolic antioxidant is 0.15%-0.3%, wherein the hindered phenolic antioxidant is pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]; The antioxidant phosphite is 0.05%-0.12%, wherein the antioxidant phosphite is tris(2,4-di-tert-butylphenyl) phosphite; Cuprous iodide 0.02%-0.05%; Potassium iodide 0.04%-0.1%; Polyethylene wax 0.1%-0.25%.

2. The high wear-resistant and high heat-resistant polyamide modified fiber composite material according to claim 1, characterized in that: The polyamide matrix resin is composed of polyamide 66 and semi-aromatic polyamide, wherein the mass percentage of polyamide 66 is 34%-44% and the mass percentage of semi-aromatic polyamide is 18%-22%; the semi-aromatic polyamide is any one of PA6T / 66, PA6T / 6I or PA9T.

3. The high wear-resistant and high heat-resistant polyamide modified fiber composite material according to claim 1, characterized in that: The chopped glass fibers are glass fibers that have undergone silane sizing treatment.

4. The high wear-resistant and high heat-resistant polyamide-modified fiber composite material according to claim 1, characterized in that: The mass ratio of the polytetrafluoroethylene to the graphite is 1:

1.

5. A method for preparing a high wear-resistant and high heat-resistant polyamide modified fiber composite material, used to prepare the high wear-resistant and high heat-resistant polyamide modified fiber composite material as described in any one of claims 1-4, characterized in that, include: S1. Provides a polyamide matrix resin, chopped glass fiber, polytetrafluoroethylene, graphite, hexagonal boron nitride, sheet-like inorganic filler, nano-silica, a reactive compatibilizer containing epoxy groups, γ-aminopropyltriethoxysilane, hindered phenolic antioxidant, phosphite antioxidant, cuprous iodide, potassium iodide, and polyethylene wax; the polyamide matrix resin is dried to meet the moisture content requirements for melt blending; S2. The polytetrafluoroethylene and the graphite are metered and their mass ratio is 1:

1. Then, they are premixed with the hexagonal boron nitride, the sheet-like inorganic filler and the nano-silica to obtain a wear-resistant and heat-resistant functional additive premix. S3. The dried polyamide matrix resin and the reactive compatibilizer containing epoxy groups are fed into the main feed port of a twin-screw extruder for melt plasticization. The wear-resistant and heat-resistant functional additive premix is ​​added and dispersed through the side feed port. The γ-aminopropyltriethoxysilane, the hindered phenolic antioxidant, the phosphite antioxidant, the cuprous iodide, the potassium iodide, and the polyethylene wax are added to the melt and mixed. In the downstream mixing section of the extruder, the chopped glass fiber is added through the side feed port to obtain a mixed melt. S4. After vacuum devolatilization of the compounded melt, it is extruded into strips, cooled, and pelletized to obtain composite material granules; S5. Cool, screen and package the composite material granules to obtain the finished composite material.

6. The method for preparing a high wear-resistant and high heat-resistant polyamide modified fiber composite material according to claim 5, characterized in that: After drying, the polyamide matrix resin has a moisture content of no more than 0.10 wt%; the moisture content is determined by the Karl Fischer method.

7. The method for preparing a high wear-resistant and high heat-resistant polyamide modified fiber composite material according to claim 5, characterized in that: The premixing is performed using a mixer with a speed of 800 r / min-1200 r / min and a mixing time of 3 min-8 min. The polytetrafluoroethylene, graphite, hexagonal boron nitride, flake inorganic filler, and nano-silica are added to the mixer in the following order to obtain the wear-resistant and heat-resistant functional additive premix.

8. The method for preparing a high wear-resistant and high heat-resistant polyamide modified fiber composite material according to claim 5, characterized in that: The twin-screw extruder has a screw length-to-diameter ratio of 40-48, and the set temperature for each temperature zone of the twin-screw extruder is 250℃-290℃, with a screw speed of 200r / min-350r / min.

9. The method for preparing a high wear-resistant and high heat-resistant polyamide modified fiber composite material according to claim 5, characterized in that: The γ-aminopropyltriethoxysilane, the hindered phenolic antioxidant, the phosphite antioxidant, the cuprous iodide, and the potassium iodide are added to the melt and mixed before the chopped glass fibers are added. The chopped glass fibers are added through a side feed port located at 0.65 to 0.80 times the effective length of the screw.

10. The method for preparing a high wear-resistant and high heat-resistant polyamide modified fiber composite material according to claim 5, characterized in that: The vacuum degree of the vacuum devolatilization corresponds to an absolute pressure of 5kPa-15kPa; after extrusion into strips, water cooling is used for cooling, with a cooling medium temperature of 15℃-30℃; the finished composite material is sealed and packaged using moisture-proof packaging material.

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