Polydopamine modified high-wear-resistance polyphenylene sulfide material and preparation method thereof

Abstract

The invention relates to the technical field of high polymer material preparation, in particular to a polydopamine modified high-wear-resistance polyphenylene sulfide material and a preparation method thereof. According to the polydopamine modified high-wear-resistance polyphenylene sulfide material, modified polydopamine is of a structure with molybdenum disulfide or graphite as a core and polydopamine as a shell. Molybdenum disulfide or graphite is modified through polydopamine, the activity of molybdenum disulfide or graphite is improved, then through the synergistic effect of added components such as glass fibers, ultra-high molecular weight polyethylene, an antioxidant and a lubricating agent, by improving dispersion of a wear-resistant filler in a polyphenylene sulfide base material, the wear resistance of the polyphenylene sulfide material is improved, and the wear resistance of the polyphenylene sulfide material is improved. Meanwhile, the comprehensive mechanical property of the material is improved, and the application of the material in wider fields is expanded.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material preparation, and in particular to a polydopamine-modified high-wear-resistant polyphenylene sulfide material and a preparation method thereof. Background Art

[0002] Polyphenylene sulfide (PPS) is a high-performance thermoplastic with excellent strength, rigidity, fatigue resistance, heat resistance, dimensional stability and chemical corrosion resistance. It is a special engineering plastic with excellent comprehensive performance and can be processed and formed in a variety of ways. However, due to its high crystallinity and brittleness, conventional polyphenylene sulfide cannot meet the requirements when used as friction parts such as piston rings, exhaust circulation valves and automotive internal parts. Therefore, it is necessary to prepare a polyphenylene sulfide material with excellent wear resistance.

[0003] Patent CN 102876039A, published on January 16, 2013, discloses a wear-resistant and high-toughness polyphenylene sulfide composite material and its preparation method. The wear-resistant PPS composite material is prepared by compounding glass fiber, carbon fiber, molybdenum disulfide and PTFE powder. However, due to poor dispersion of the wear-resistant filler, its wear resistance level cannot meet the requirements of long-term wear resistance.

[0004] Patent CN 110615988A, published on December 27, 2019, discloses a highly wear-resistant polyphenylene sulfide material and a preparation method thereof. It uses PPS as the base material, PA66 and a toughening agent, and selects short-cut carbon fiber and ultra-high molecular weight polyethylene powder for modification. However, since mechanical properties and wear resistance cannot be taken into account at the same time, and the raw materials of carbon fiber are expensive, it is still limited in some usage scenarios.

[0005] Patent CN 111057373B, published on June 28, 2022, discloses a PPS wear-resistant material and a preparation method thereof. The PPS wear-resistant material is prepared by grafting polytetrafluoroethylene with styrene to improve the compatibility of PTFE and PPS materials. However, the strength of the material is low and cannot meet some working conditions.

[0006] Therefore, how to prepare a polyphenylene sulfide material with excellent wear resistance and comprehensive mechanical properties is a technical problem that technicians in this field need to solve. Summary of the invention

[0007] In order to solve the above problem: how to prepare a polyphenylene sulfide material with excellent wear resistance and comprehensive mechanical properties, the present invention provides a polydopamine-modified high wear-resistant polyphenylene sulfide material and a preparation method thereof, and the technical scheme thereof is as follows: The present invention provides a polydopamine-modified high-wear-resistant polyphenylene sulfide material, which comprises, by weight: Polyphenylene sulfide 50-100 parts; 30~60 parts of glass fiber; Ultra high molecular weight polyethylene 5~10 parts; 2 to 10 parts of polydopamine modified wear-resistant particles; Antioxidant 0.1~0.5 parts; Lubricant 0.2~0.6 parts; The modified polydopamine has a structure with molybdenum disulfide or graphite as a core and polydopamine as a shell.

[0008] Preferably, the modified polydopamine is prepared by the following method: MoS2 or graphite is dispersed in a solution containing dopamine, tris(hydroxymethyl)aminomethane is used as a buffer, the weight ratio of polydopamine to MoS2 or graphite is controlled to be 1.5-2.2:1, mechanically stirred at 30-50°C for 6-12 hours, washed and filtered to obtain polydopamine-modified wear-resistant particles.

[0009] Preferably, the pH of the buffer solution is 8.0-9.0.

[0010] Preferably, the polyphenylene sulfide is linear polyphenylene sulfide or cross-linked polyphenylene sulfide.

[0011] More preferably, the polyphenylene sulfide is cross-linked polyphenylene sulfide.

[0012] Preferably, the melt index of the polyphenylene sulfide is 300, 500 or 1000.

[0013] Preferably, the melt index of the polyphenylene sulfide is 1000.

[0014] Preferably, the glass fiber is alkali-free untwisted roving glass fiber.

[0015] Preferably, the particle size of the ultra-high molecular weight polyethylene is 100-200 μm, and the viscosity-average molecular weight is 100-500w.

[0016] Preferably, the antioxidant is one or more of tris(2,4-di-tert-butylphenyl)phosphite, tetrakis(2,4-di-tert-butylphenyl-4,4-biphenyl)bisphosphate, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine or tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0017] Preferably, the lubricant is one or more of ethylene-acrylic acid copolymer, calcium stearate or lithium stearate.

[0018] The present invention also provides a method for preparing the polydopamine-modified high-wear-resistant polyphenylene sulfide material as described above, comprising the following steps: S1. Weigh polyphenylene sulfide, glass fiber, ultra-high molecular weight polyethylene, polydopamine-modified wear-resistant particles, antioxidant, and lubricant according to a weight ratio, add them into a high-speed mixer, and stir them continuously until they are uniform to obtain a premix; S2, putting the premix into a twin-screw extruder for melting, mixing and granulation, the processing temperature of the twin-screw extruder is 280-300°C, the feeding frequency is 10-30Hz, and the screw speed is 300-500rpm; then the extruded particles are dried at 100-130°C for 4-6h; S3. The extruded particles are molded into relevant strips on a horizontal injection molding machine, with an injection temperature of 300-320°C and a mold temperature of 130-160°C.

[0019] Compared with the prior art, the polydopamine-modified highly wear-resistant polyphenylene sulfide material provided by the present invention has the following advantages: The polydopamine-modified highly wear-resistant polyphenylene sulfide material of the present invention improves the activity of molybdenum disulfide or graphite by modifying molybdenum disulfide or graphite through polydopamine, and then improves the dispersion of wear-resistant fillers in the polyphenylene sulfide matrix through the synergistic effect of adding components such as glass fiber, ultra-high molecular weight polyethylene, antioxidants and lubricants, thereby not only improving the wear resistance of the polyphenylene sulfide material, but also improving the comprehensive mechanical properties of the material, thereby expanding its application in a wider range of fields.

[0020] In a preferred embodiment, the particle size of the ultra-high molecular weight polyethylene is 100-200 μm, and the viscosity average molecular weight is 100-500w, which can reduce the friction coefficient of the material surface and improve the wear resistance of the polyphenylene sulfide material. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In order to solve the problem of how to prepare a polyphenylene sulfide material with excellent wear resistance and comprehensive mechanical properties, the present invention provides a polydopamine-modified high wear-resistant polyphenylene sulfide material and a preparation method thereof, and the technical scheme thereof is as follows: A polydopamine-modified highly wear-resistant polyphenylene sulfide material, comprising, by weight: Polyphenylene sulfide 50-100 parts; 30~60 parts of glass fiber; Ultra high molecular weight polyethylene 5~10 parts; 2 to 10 parts of polydopamine modified wear-resistant particles; Antioxidant 0.1~0.5 parts; Lubricant 0.2~0.6 parts; The modified polydopamine has a structure with molybdenum disulfide or graphite as a core and polydopamine as a shell.

[0023] Furthermore, the modified polydopamine is prepared by the following method: MoS2 or graphite is dispersed in a solution containing dopamine, tris(hydroxymethyl)aminomethane is used as a buffer, the weight ratio of polydopamine to MoS2 or graphite is controlled to be 1.5-2.2:1, mechanically stirred at 30-50°C for 6-12 hours, washed and filtered to obtain polydopamine-modified wear-resistant particles.

[0024] Furthermore, the pH of the buffer solution is 8.0-9.0; further, the polyphenylene sulfide is linear polyphenylene sulfide or cross-linked polyphenylene sulfide.

[0025] Preferably, the polyphenylene sulfide is cross-linked polyphenylene sulfide. Compared with linear polyphenylene sulfide, the strength of the polyphenylene sulfide material can be improved when cross-linked polyphenylene sulfide is used in conjunction with other materials.

[0026] Furthermore, the melt index of the polyphenylene sulfide is 300, 500 or 1000.

[0027] Preferably, the melt index of the polyphenylene sulfide is 1000, which can shorten the molding cycle of the polyphenylene sulfide material and improve production efficiency during the processing.

[0028] Furthermore, the glass fiber is an alkali-free untwisted roving glass fiber, which has good bundling and ribbon-forming properties, can be quickly and thoroughly soaked in the resin, has no hairiness, and provides excellent mechanical properties for the polyphenylene sulfide material.

[0029] Furthermore, the particle size of the ultra-high molecular weight polyethylene is 100-200 μm. Within this range, it can not only provide better fluidity for the processing process, but also avoid the wear problem during the processing caused by too small particle size, thereby improving the mechanical properties of the polyphenylene sulfide material.

[0030] Furthermore, the viscosity average molecular weight of the ultra-high molecular weight polyethylene is 100~500w.

[0031] Furthermore, the antioxidant is one or more of tris(2,4-di-tert-butylphenyl)phosphite, tetrakis(2,4-di-tert-butylphenyl-4,4-biphenyl)bisphosphate, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine or tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester.

[0032] Furthermore, the lubricant is one or more of ethylene-acrylic acid copolymer, calcium stearate or lithium stearate.

[0033] A method for preparing a polydopamine-modified highly wear-resistant polyphenylene sulfide material comprises the following steps: S1. Weigh polyphenylene sulfide, glass fiber, ultra-high molecular weight polyethylene, polydopamine-modified wear-resistant particles, antioxidant, and lubricant according to a weight ratio, add them into a high-speed mixer, and stir them continuously until they are uniform to obtain a premix; S2, putting the premix into a twin-screw extruder for melting, mixing and granulation, the processing temperature of the twin-screw extruder is 280-300°C, the feeding frequency is 10-30Hz, and the screw speed is 300-500rpm; then the extruded particles are dried at 100-130°C for 4-6h; S3. The extruded particles are molded into relevant strips on a horizontal injection molding machine, with an injection temperature of 300-320°C and a mold temperature of 130-160°C.

[0034] It should be noted that those skilled in the art can adjust the specific preparation process according to actual conditions.

[0035] The present invention also provides the following embodiments and comparative examples: Example 1 By weight, 50 parts of cross-linked polyphenylene sulfide, 30 parts of glass fiber, 5 parts of ultra-high molecular weight polyethylene, 2 parts of polydopamine-modified wear-resistant particles, 0.1 parts of an antioxidant and 0.2 parts of a lubricant are mixed to obtain a mixture.

[0036] The mixture is added to a high-speed mixer and stirred continuously until uniform to obtain a premix, and the premix is ​​put into a twin-screw extruder for melt mixing and granulation.

[0037] Example 2 In parts by weight, 100 parts of cross-linked polyphenylene sulfide, 60 parts of glass fiber, 10 parts of ultra-high molecular weight polyethylene, 10 parts of polydopamine-modified wear-resistant particles, 0.5 parts of an antioxidant and 0.6 parts of a lubricant are mixed to obtain a mixture.

[0038] The remaining steps and operations are the same as those in Example 1.

[0039] Example 3 By weight, 75 parts of cross-linked polyphenylene sulfide, 45 parts of glass fiber, 7 parts of ultra-high molecular weight polyethylene, 6 parts of polydopamine-modified wear-resistant particles, 0.3 parts of an antioxidant and 0.4 parts of a lubricant are mixed to obtain a mixture.

[0040] The mixture is added to a high-speed mixer and stirred continuously until uniform to obtain a premix, and the premix is ​​put into a twin-screw extruder for melt mixing and granulation.

[0041] The remaining steps and operations are the same as those in Example 1.

[0042] Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that no polydopamine-modified wear-resistant particles are added, and the remaining steps and operations are the same as those in Example 3.

[0043] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that the cross-linked polyphenylene sulfide is replaced by linear polyphenylene sulfide, and the remaining steps and operations are the same as those of Example 3.

[0044] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that the wear-resistant particles are not subjected to polydopamine modification treatment, and the remaining steps and operations are the same as those of Example 3.

[0045] It should be noted that if no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in the field or the product instructions are used, and the reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased on the market.

[0046] The materials obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to performance tests, and the test methods were as follows: 1. Wear resistance test Refer to the national standard GB / T 3690 (300N load, 2m / s friction rate, 2h friction). Among them, the life refers to the wear time (in hours) of the sample under test when the wear amount is 1000mg; the wear rate is calculated as wear volume / (load×sliding distance) unit: 10~6mm3 / (N·m).

[0047] 2. Mechanical properties test Tensile strength test standard: ISO 527 (10mm / min test rate); Bending strength test standard: ISO 178 (2mm / min test rate).

[0048] The wear resistance and mechanical properties of the highly wear-resistant polyphenylene sulfide materials prepared in the above Examples 1 to 3 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 1: Table 1

[0049] As can be seen from Table 1, compared with Comparative Example 1 without adding modified polydopamine-modified wear-resistant particles and Comparative Example 3 with adding wear-resistant particles that are not modified with polydopamine, the life of Examples 1 to 3 is significantly improved, the wear amount and wear rate are significantly reduced, and the wear resistance is significantly improved; and the bending strength of Examples 1 to 3 is significantly enhanced, and the tensile strength of Examples 1 and 3 is significantly enhanced, and the comprehensive mechanical properties of the material are significantly improved. Comparative Example 2 uses linear polyphenylene sulfide. Compared with Comparative Example 2, the wear resistance of Examples 1 to 3 is significantly improved, indicating that the use of cross-linked polyphenylene sulfide can synergistically improve the wear resistance of polyphenylene sulfide materials. Comparing Example 3 with Comparative Example 3, the mechanical properties and wear resistance data of Comparative Example 3 are significantly lower than those of Example 3, mainly because the wear-resistant particles that are not modified with polydopamine are poorly dispersed when filled into polyphenylene sulfide, and agglomeration occurs.

[0050] In summary, the polydopamine-modified highly wear-resistant polyphenylene sulfide material of the present invention improves the activity of molybdenum disulfide or graphite by modifying molybdenum disulfide or graphite through polydopamine, and then improves the dispersion of wear-resistant fillers in the polyphenylene sulfide matrix through the synergistic effect of adding components such as glass fiber, ultra-high molecular weight polyethylene, antioxidants and lubricants, which not only improves the wear resistance of the polyphenylene sulfide material, but also improves the comprehensive mechanical properties of the material, thereby expanding its application in a wider field.

[0051] Although the terms such as polyphenylene sulfide, modified polydopamine and ultra-high molecular weight polyethylene are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly wear-resistant polyphenylene sulfide material modified with polydopamine, characterized in that: The components include, by weight: Polyphenylene sulfide 50-100 parts; 30~60 parts of glass fiber; Ultra high molecular weight polyethylene 5~10 parts; 2 to 10 parts of polydopamine modified wear-resistant particles; Antioxidant 0.1~0.5 parts; Lubricant 0.2~0.6 parts; The polydopamine modified wear-resistant particles have a structure with molybdenum disulfide or graphite as a core and polydopamine as a shell.

2. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 1, characterized in that: The polydopamine modified wear-resistant particles are prepared by the following method: MoS2 or graphite is dispersed in a solution containing dopamine, tris(hydroxymethyl)aminomethane is used as a buffer, the weight ratio of polydopamine to MoS2 or graphite is controlled to be 1.5-2.2:1, mechanically stirred at 30-50°C for 6-12 hours, washed and filtered to obtain polydopamine-modified wear-resistant particles.

3. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 2, characterized in that: The pH of the buffer solution is 8.0-9.

0.

4. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 1, characterized in that: The polyphenylene sulfide is linear polyphenylene sulfide or cross-linked polyphenylene sulfide.

5. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 1, characterized in that: The melt index of the polyphenylene sulfide is 300, 500 or 1000.

6. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 1, characterized in that: The glass fiber is alkali-free untwisted roving glass fiber.

7. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 1, characterized in that: The particle size of the ultra-high molecular weight polyethylene is 100-200 μm, and the viscosity average molecular weight is 100-500w.

8. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 1, characterized in that: The antioxidant is one or more of tris(2,4-di-tert-butylphenyl)phosphite, tetrakis(2,4-di-tert-butylphenyl-4,4-biphenyl)bisphosphate, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine or tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester.

9. The polydopamine-modified highly wear-resistant polyphenylene sulfide material according to claim 1, characterized in that: The lubricant is one or more of ethylene-acrylic acid copolymer, calcium stearate or lithium stearate.

10. A method for preparing the polydopamine-modified highly wear-resistant polyphenylene sulfide material according to any one of claims 1 to 9, characterized in that: The steps include: S1. Weigh polyphenylene sulfide, glass fiber, ultra-high molecular weight polyethylene, polydopamine-modified wear-resistant particles, antioxidant, and lubricant according to a weight ratio, add them into a high-speed mixer, and stir them continuously until they are uniform to obtain a premix; S2, putting the premix into a twin-screw extruder for melting, mixing and granulation, the processing temperature of the twin-screw extruder is 280-300°C, the feeding frequency is 10-30Hz, and the screw speed is 300-500rpm; then the extruded particles are dried at 100-130°C for 4-6h; S3. The extruded particles are molded into relevant strips on a horizontal injection molding machine, with an injection temperature of 300-320°C and a mold temperature of 130-160°C.

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