A heat-resistant polyethylene material and preparation method thereof

Abstract

The present invention relates to the technical field of heat-resistant materials, and specifically relates to a heat-resistant polyethylene material and a preparation method thereof, comprising the following raw materials: ultra-high molecular weight polyethylene, zirconia-zinc aluminate spinel (ZrO2-ZnAl2O4), modified graphdiyne, antioxidant, heat stabilizer, plasticizer, flame retardant, and ultraviolet light absorber. In the present invention, ultra-high molecular weight polyethylene, ZrO2-ZnAl2O4, and modified graphdiyne act through a synergistic effect. During the high-temperature radiation process, the polyethylene molecular chains form a firm three-dimensional network structure, providing a stable matrix support. The excellent chemical stability and oxidation resistance of ZrO2-ZnAl2O4 in a high-temperature environment effectively inhibit the thermal degradation reaction of polyethylene and extend the service life of the material. Modified graphdiyne helps to rapidly spread heat, improve the thermal stability of the material, and at the same time its layered structure has good lubricating properties, avoiding heat accumulation and material aging caused by frictional effects. Ultra-high molecular weight cross-linked polyethylene, ZrO2-ZnAl2O4, and modified graphdiyne form a multi-level protection system to jointly improve the thermal stability of the material.

Description

Technical Field

[0001] The invention relates to the technical field of heat-resistant materials, in particular to a heat-resistant polyethylene material and a preparation method thereof. Background Art

[0002] Polyethylene is one of the most common thermoplastics, with excellent chemical stability, good electrical insulation and processability. These advantages make polyethylene widely used in many fields such as pipelines, packaging, electronics, and medical treatment. However, the heat resistance of polyethylene is relatively poor, and its heat deformation temperature is usually between 60 and 90 ° C, which makes it easy to deform and age in high temperature environments, limiting its application in high temperature environments. For example, the application of polyethylene in vehicles, electronic product housings, home appliances, buildings, and piping systems often faces high operating temperatures. If it does not have sufficient heat resistance, polyethylene will soften, deform, or crack under high temperature conditions, resulting in product failure. In some special applications, such as automobiles, aerospace, military, high-end electronic equipment, and geothermal energy mining, polyethylene not only needs to have high mechanical strength and chemical stability, but also needs to withstand high temperature loads. Therefore, in order to expand the application field of polyethylene, it is crucial to improve its heat resistance. Enhancing the heat resistance of polyethylene not only improves the thermal stability of the material in high temperature environments, but also extends its service life in high temperature environments, maintains its original mechanical strength, maintains morphological stability, reduces processing defects caused by thermal deformation, thereby improving production efficiency and product quality, and further broadens the scope of application, which will bring greater growth space for the market demand for polyethylene. Summary of the invention

[0003] (1) Technical issues to be resolved

[0004] The purpose of the present invention is to provide a heat-resistant polyethylene material and a preparation method thereof, by optimizing the material formula of the heat-resistant polyethylene material, and combining modern nanotechnology and high-temperature radiation cross-linking technology to significantly improve the heat resistance of the polyethylene material, thereby expanding its application range in high-temperature environments and effectively improving its service life and comprehensive performance.

[0005] (2) Technical solution

[0006] To achieve the above object, on the one hand, the present invention provides a heat-resistant polyethylene material, comprising the following raw materials in parts by weight: 70-90 parts of ultra-high molecular weight polyethylene, 1-3 parts of modified graphene, 0.5-2 parts of antioxidant, 0.5-2 parts of heat stabilizer, 1-5 parts of plasticizer, 1-3 parts of flame retardant, and 0.5-2 parts of anti-ultraviolet agent;

[0007] The heat-resistant polyethylene material also includes:

[0008] Zirconia-zinc aluminum spinel (ZrO2-ZnAl2O4);

[0009] The weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3: (70-90);

[0010] The ZrO2-ZnAl2O4 particle size is 40-60 nm and the specific surface area is 100-120 m 2 / g.

[0011] Furthermore, the preparation method of ZrO2-ZnAl2O4 comprises:

[0012] S11. Dissolve zinc nitrate and aluminum nitrate in purified water under stirring, control the molar ratio of zinc nitrate and aluminum nitrate to be 1:2, slowly add ammonia solution after stirring for 0.5 to 1 h, adjust the pH value to 9 to 10, and continue stirring for 2 to 4 h to obtain a first mixed solution;

[0013] S12. The first mixed solution was aged at room temperature for 12 to 15 hours, and then the supernatant was removed. The solid was washed with purified water five times and then dried by blast drying at a temperature of 85 to 105° C. After drying for 12 to 14 hours, the solid was calcined in a muffle furnace at 500 to 600° C. for 4 to 6 hours to obtain ZnAl2O4, which was ground into powder for later use;

[0014] S13. Add ZnAl2O4 powder to purified water and perform ultrasonic treatment at a frequency of 40 to 50 kHz. After 1 to 2 hours of ultrasonic treatment, a ZnAl2O4 suspension is obtained. Dissolve zirconium nitrate in purified water under stirring and stir for 0.5 to 1 hour to obtain a zirconium nitrate solution.

[0015] S14. The zirconium nitrate solution was slowly added dropwise to the ZnAl2O4 suspension under stirring, and ammonia was slowly added dropwise after stirring for 0.5 to 1 h, and the pH value was adjusted to 9 to 10. The stirring was continued for 2 to 4 h to obtain a second mixed solution, and the molar ratio of zirconium nitrate to zinc nitrate was controlled to be (0.05 to 0.2):1;

[0016] S15. The second mixed solution is allowed to stand and age at room temperature for 12 to 15 hours, and then the supernatant is removed. The obtained solid is washed with purified water for 5 times and then dried by forced air at a drying temperature of 85 to 105°C. After drying for 12 to 14 hours, the solid is placed in a muffle furnace and calcined at 550 to 650°C for 4 to 6 hours to obtain ZrO2-ZnAl2O4, which is ground into powder for later use.

[0017] Furthermore, the preparation method of the modified graphyne comprises:

[0018] S21. Add graphyne powder to anhydrous ethanol and perform ultrasonic treatment at a frequency of 40 to 50 kHz. After ultrasonic treatment for 0.5 to 1 h, place in a tube furnace and dry under nitrogen protection at a temperature of 50 to 60 ° C. After drying for 12 to 14 h, obtain a graphyne intermediate and grind it into a powder for later use;

[0019] S22. Dispersing the graphyne intermediate in dimethylformamide under stirring and nitrogen protection, heating to 75-85°C, stirring for 0.5-1h, slowly adding n-butyl lithium and copper powder, and continuing to stir and react for 12-14h to obtain a third mixed solution, wherein the mass ratio of graphyne to n-butyl lithium is 1:(3-5);

[0020] S23. The third mixed solution is subjected to high-speed centrifugation at a speed of 10,000-12,000 rpm for 10-15 min. The separated solid is washed alternately with dimethylformamide and purified water for 5 times and then vacuum dried at a drying temperature of 55-65° C. After drying for 18-24 h, the modified graphyne is obtained and ground into powder for later use.

[0021] Furthermore, the modified gyne is obtained by modifying the surface of gyne with an alkyl group, and the particle size of the modified gyne is 30-50 nm, and the specific surface area is 450-500 m 2 / g.

[0022] Furthermore, the antioxidant is a compound of catechol, 2,6-di-tert-butyl-p-cresol and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the weight ratio of catechol, 2,6-di-tert-butyl-p-cresol and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is (1~2):(0.5~1):(0.2~0.4).

[0023] Furthermore, the heat stabilizer is a compound of zinc stearate and dibutyltin dilaurate, and the weight ratio of zinc stearate to dibutyltin dilaurate is (1-0.5): (1-1.5).

[0024] Furthermore, the plasticizer is one or more of dioctyl phthalate, diisononyl phthalate, calcium stearate, trimethyl phosphate and diisooctyl adipate.

[0025] Furthermore, the flame retardant is a compound of tin dioxide, brominated epoxy resin and sodium silicate, and the weight ratio of tin dioxide, brominated epoxy resin and sodium silicate is (1-2): (2-3): (5-6).

[0026] Furthermore, the anti-ultraviolet agent is one or more of 2-hydroxy-4-methoxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(2'-hydroxy-5'-methylphenyl).

[0027] On the other hand, based on the same inventive concept, the present invention also provides a method for preparing a heat-resistant polyethylene material, which is applied to the heat-resistant polyethylene material, comprising the following steps:

[0028] S31. Ultra-high molecular weight polyethylene, antioxidant, heat stabilizer, plasticizer, flame retardant and UV inhibitor were sequentially added to a high shear mixer, and the temperature was raised to 150-180°C and heated for 2-4 hours to obtain a first mixture;

[0029] S32. The ZrO2-ZnAl2O4 and modified graphene were added to the first mixture, and the high shear mixer was started at a speed of 4000 to 4500 rpm to obtain a second mixture after running for 20 to 30 min;

[0030] S33. The second mixture is poured into an extruder for granulation, and then a corresponding mold is used in an injection molding machine to prepare a desired shape. The extrusion temperature is controlled to be 190-220°C. The extruded material is subjected to high-temperature radiation cross-linking treatment using electron beam radiation with a radiation dose of 20-30 kGy. After treatment for 10-15 minutes, a heat-resistant polyethylene material is obtained.

[0031] The mechanism of action of the above raw material components is as follows:

[0032] In the heat-resistant polyethylene material, ultra-high molecular weight polyethylene, ZrO2-ZnAl2O4 and modified graphyne work together to improve the heat resistance of the material through synergistic effects. The viscosity-average molecular weight of ultra-high molecular weight polyethylene is greater than 1.5 million, and it has extremely high molecular weight and excellent mechanical properties. The strong intermolecular interaction of its ultra-long polymer chains can effectively resist the molecular chain slip and plastic deformation caused by high temperature. At the same time, during the high-temperature radiation cross-linking process, the polyethylene molecular chains undergo cross-linking reactions to form a more solid three-dimensional network structure, providing a stable matrix support for ZrO2-ZnAl2O4 and modified graphyne, so that both can be evenly dispersed in the polyethylene matrix. ZrO2-ZnAl2O4 is obtained by doping ZrO2 in the zinc aluminum spinel structure (ZnAl2O4). It has good thermal conductivity and can effectively disperse the heat inside the material to avoid heat accumulation, thereby improving the high temperature resistance of the material. ZrO2-ZnAl2O4 has excellent chemical stability and oxidation resistance in high temperature environment, which can effectively inhibit the oxidation and decomposition reaction of polyethylene at high temperature and prolong its service life. In addition, ZrO2-ZnAl2O4 has good compatibility with ultra-high molecular weight polyethylene. By enhancing the interfacial bonding force between the two, the mechanical properties and thermal stability of the material are further improved to avoid the structural damage of the material caused by thermal expansion. Glottyne is a two-dimensional material with a unique acetylenic bond structure. Modified graphyne is obtained by modification with alkylated groups. Modified graphyne exhibits excellent thermal conductivity. Its acetylenic group (C≡C) structure and layered arrangement are conducive to the rapid spread of heat, which can effectively conduct local heat to the entire material, thereby improving the thermal stability of the material. The alkylated groups on the surface of modified Graphyne further increase its compatibility with the ultra-high molecular weight polyethylene matrix, allowing the modified Graphyne to be more evenly dispersed in the matrix to avoid agglomeration. The good dispersibility also further enhances the overall thermal stability and mechanical properties of the material. In addition, the layered structure of modified Graphyne has good lubricity, which helps to reduce the friction coefficient inside the material and reduce the local heat generated by friction, thereby avoiding heat accumulation and material aging caused by friction. In short, in the cross-linked polyethylene matrix, ZrO2-ZnAl2O4 and modified Graphyne can be evenly dispersed in the matrix, effectively improving the overall thermal conductivity of the material, helping the material to evenly disperse heat under high temperature conditions and avoid local overheating. At the same time, modified Graphyne and ZrO2-ZnAl2O4 enhance the interfacial bonding force between the polyethylene matrix, thereby forming a stronger interfacial interaction and enhancing the overall structural stability of the material. In addition, the high temperature stability and antioxidant properties of ZrO2-ZnAl2O4 further enhance the stability of the material at high temperatures. The modified graphyne, through its good chemical stability, enables the material to maintain excellent performance at high temperatures and is not prone to thermal degradation. The interaction of the three forms a multi-level protection system, which jointly improves the thermal stability of the material.

[0033] The function of the antioxidant is to prevent the polyethylene material from being oxidized and degraded in a high temperature and oxygen environment, thereby extending the service life of the material. The antioxidant of the present invention is a compound of catechol, 2,6-di-tert-butyl-p-cresol and tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester. The catechol can absorb and neutralize free radicals to prevent the polyethylene from being oxidized at high temperatures. The 2,6-di-tert-butyl-p-cresol and tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester can delay the aging process of the polyethylene material by inhibiting the oxidation reaction, thereby improving the heat resistance and service life of the material.

[0034] The function of the heat stabilizer is to enhance the resistance of polyethylene to thermal degradation and discoloration caused by high temperature during processing and use. The heat stabilizer of the present invention is a compound of zinc stearate and dibutyltin dilaurate, wherein zinc stearate can form a complex with impurities such as chlorine and nitrogen in polyethylene, thereby effectively reducing the degradation of polyethylene caused by pyrolysis during heating, and dibutyltin dilaurate, as a metal salt heat stabilizer, can inhibit the thermal degradation of polyethylene under high temperature conditions, increase the processing stability of the material, and improve the thermal stability.

[0035] The role of plasticizers is to improve the flexibility and processing properties of polyethylene, especially at low temperatures, it can improve the processing and molding properties of the material. Dioctyl phthalate, diisononyl phthalate, calcium stearate, trimethyl phosphate and diisooctyl adipate are commonly used plasticizers. Plasticizers penetrate into the molecular chains of polyethylene, increase the degree of freedom between the molecular chains, and reduce the glass transition temperature of polyethylene, thereby improving the flexibility and ductility of the material.

[0036] The flame retardant is used to improve the flame retardancy of polyethylene materials, reduce their burning speed in fire, and prevent the spread of fire. The flame retardant of the present invention is a compound of tin dioxide, brominated epoxy resin and sodium silicate, wherein tin dioxide can react with oxygen at high temperature to form a stable tin oxide layer, thereby isolating oxygen and inhibiting combustion; brominated epoxy resin can release bromine free radicals through chemical reactions, block the propagation of free radicals in the combustion reaction, effectively reduce the chain reaction in the combustion process, and reduce the combustion rate; sodium silicate, as an inorganic flame retardant, can generate a protective shielding layer at high temperature to prevent flame propagation and reduce the generation of combustion gas.

[0037] The function of UV inhibitors is to improve the ability of polyethylene materials to resist UV degradation and prevent light aging caused by UV rays. 2-Hydroxy-4-methoxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(2'-hydroxy-5'-methylphenyl) are commonly used UV inhibitors. 2-Hydroxy-4-methoxybenzoate has the ability to absorb UV radiation and reduce its damage to the polyethylene molecular chain. 2-(2'-hydroxy-5'-methylphenyl)benzotriazole can protect polyethylene from oxidation and degradation caused by UV rays by absorbing UV rays and converting them into harmless heat energy. 2-(2'-hydroxy-5'-methylphenyl) can stabilize the molecular structure of the material and reduce the breakage and aging of the molecular chain under UV irradiation.

[0038] (3) Beneficial effects

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. Ultra-high molecular weight polyethylene, ZrO2-ZnAl2O4 and modified graphyne work through synergistic effects. During the high-temperature radiation cross-linking process, the polyethylene molecular chains undergo cross-linking reactions to form a strong three-dimensional network structure, providing a stable matrix support for ZrO2-ZnAl2O4 and modified graphyne.

[0041] 2. ZrO2-ZnAl2O4 has good thermal conductivity, excellent chemical stability and oxidation resistance in high temperature environment, and can effectively inhibit the oxidation and decomposition reaction of polyethylene at high temperature, thus extending the service life of the material;

[0042] 3. The acetylene structure and layered arrangement of modified graphyne help to quickly spread heat and improve the thermal stability of the material. Its layered structure has good lubrication properties, avoiding heat accumulation and material aging caused by friction.

[0043] 4. In the cross-linked polyethylene matrix, ZrO2-ZnAl2O4 and modified graphyne can be evenly dispersed in the matrix. The high temperature stability and antioxidant properties of ZrO2-ZnAl2O4 enhance the stability of the material at high temperatures. The modified graphyne, through its good chemical stability, enables the material to maintain excellent performance at high temperatures, forming a multi-level protection system to jointly improve the thermal stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the SEM image of ZrO2-ZnAl2O4 of Example 1 of the present invention;

[0045] Figure 2 This is the SEM image of the modified graphyne in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0047] The test equipment and preparations of the embodiments described below are as follows: electronic balance (Mettler), electric constant temperature water bath (Jiangsu Kedao), magnetic stirrer (Germany Aika), ultrasonic instrument (Beijing Kemeng), high-speed centrifuge (Guangzhou Jidi), vacuum drying oven (Shanghai Yiheng), tubular furnace (Shanghai Yuzhi), muffle furnace (Shanghai Yiheng Scientific Instrument), electric blast drying oven (Suzhou Geruida), high shear mixer (Nantong Fulake), extruder (Taizhou Kedi), scanning electron microscope (Germany Zeiss), specific surface area analyzer (Beijing Best Instrument Technology), heat deformation temperature meter (Chengde Jinjian), universal material testing machine (USA MTS), IZOD impact testing machine (Shanghai Xiangyi); chemicals and reagents were purchased from Sigma-Aldrich.

[0048] Example 1: This example discloses a heat-resistant polyethylene material, comprising the following raw materials in parts by weight: 80 parts of ultra-high molecular weight polyethylene, 2 parts of modified graphyne, 1.25 parts of antioxidant, 1.25 parts of heat stabilizer, 3 parts of plasticizer, 2 parts of flame retardant, 1.25 parts of anti-ultraviolet agent, the heat-resistant polyethylene material also includes ZrO2-ZnAl2O4, the weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3:80, the particle size of ZrO2-ZnAl2O4 is 40~60 nm, and the specific surface area is 100~120m 2 / g.

[0049] In the heat-resistant polyethylene material, ultra-high molecular weight polyethylene, ZrO2-ZnAl2O4 and modified graphyne work together to improve the heat resistance of the material through synergistic effects. The viscosity-average molecular weight of ultra-high molecular weight polyethylene is greater than 1.5 million, with extremely high molecular weight and excellent mechanical properties. Its ultra-long polymer chain has stronger intermolecular interactions such as van der Waals forces and hydrogen bonds, which makes the polyethylene have good structural stability and can effectively resist molecular chain slip and plastic deformation caused by high temperature. During the high-temperature radiation cross-linking process, the free radical reaction in the polyethylene molecular chain is induced by radiation. These free radicals will cause covalent bonds to form between the polyethylene molecular chains, so that the single molecular chains are connected together by covalent bonds, thereby forming a more solid three-dimensional network structure. The heat deformation temperature and thermal stability of the cross-linked polyethylene at high temperatures are greatly improved, providing a stable matrix support for ZrO2-ZnAl2O4 and modified graphyne, so that the two can be evenly dispersed in the polyethylene matrix to prevent them from agglomerating or precipitating in the material. ZrO2-ZnAl2O4 is obtained by doping ZrO2 in the zinc aluminum spinel structure (ZnAl2O4). Figure 1 This is the SEM image of ZrO2-ZnAl2O4. It can be seen that the particle size of ZrO2-ZnAl2O4 is uniform and the morphology is spherical. ZrO2-ZnAl2O4 has good thermal conductivity. When the material is affected by high temperature or heat source, ZrO2-ZnAl2O4 can quickly transfer the heat of these local areas to the entire material, so that the heat is evenly distributed, thereby improving the material's high temperature resistance and avoiding material performance degradation caused by local overheating. Especially at high temperatures, the material will not experience "thermal collapse", thereby maintaining good structural stability. Moreover, ZrO2-ZnAl2O4 has excellent chemical stability and oxidation resistance in high temperature environments. The ceramic structure of ZrO2-ZnAl2O4 can form a protective barrier in the polyethylene matrix, reducing the direct contact of oxygen with the molecular chains of polyethylene. It can also adsorb oxygen molecules in the air to prevent oxygen from reacting with polyethylene, thereby effectively inhibiting the oxidation and decomposition reactions of polyethylene at high temperatures and extending its service life. In addition, ZrO2-ZnAl2O4 has good compatibility with ultra-high molecular weight polyethylene. By enhancing the interfacial bonding between the two, the mechanical properties and thermal stability of the material are further improved, avoiding structural damage to the material due to thermal expansion. Glotyn is a two-dimensional material with a unique acetylenic bond structure. Modified Graphyne is obtained by modification with alkylated groups. Figure 2The SEM image of modified graphyne shows that the modified graphyne has a very obvious layered structure. Modified graphyne exhibits excellent thermal conductivity. The strong covalent nature of the carbon-carbon triple bond (C≡C) in the alkynyl structure allows electrons to flow freely in the structure, helping heat to spread rapidly. Its layered structure allows each layer to serve as a channel for heat conduction, allowing heat to diffuse rapidly on the plane and evenly disperse heat, thereby improving the overall thermal conductivity of the material. The alkylated groups on the surface of the modified graphyne also further increase its compatibility with the ultra-high molecular weight polyethylene matrix, allowing the modified graphyne to be more evenly dispersed in the matrix to avoid agglomeration, and good dispersibility further enhances the overall thermal stability and mechanical properties of the material. In addition, the layered structure of the modified graphyne has good lubricity, which helps to reduce the friction coefficient inside the material, reduce the friction between the molecular chains, and reduce the local heat generated by friction, thereby avoiding heat accumulation and material aging caused by friction. In summary, in the cross-linked polyethylene matrix, ZrO2-ZnAl2O4 and modified graphyne can be evenly dispersed in the matrix, effectively improving the overall thermal conductivity of the material, helping the material to evenly disperse heat under high temperature conditions and avoid local overheating. At the same time, modified graphyne and ZrO2-ZnAl2O4 enhance the interfacial bonding force between the polyethylene matrix and form a stronger interfacial interaction, thereby enhancing the overall structural stability of the material. In addition, the high temperature stability and antioxidant properties of ZrO2-ZnAl2O4 further enhance the stability of the material at high temperatures, and modified graphyne, through its good chemical stability, enables the material to maintain excellent performance at high temperatures and is not prone to thermal degradation. The interaction of the three forms a multi-level protection system that jointly improves the thermal stability of the material.

[0050] The preparation method of ZrO2-ZnAl2O4 comprises:

[0051] S11. Dissolve zinc nitrate and aluminum nitrate in purified water under stirring, control the molar ratio of zinc nitrate and aluminum nitrate to be 1:2, slowly add ammonia solution after stirring for 0.5 to 1 h, adjust the pH value to 9 to 10, and continue stirring for 2 to 4 h to obtain a first mixed solution;

[0052] S12. The first mixed solution was aged at room temperature for 12 to 15 hours, and then the supernatant was removed. The solid was washed with purified water five times and then dried by blast drying at a drying temperature of 85 to 105 ° C. After drying for 12 to 14 hours, it was placed in a muffle furnace at 500 to 600 ° C. and calcined for 4 to 6 hours to obtain ZnAl2O4 and ground into powder for standby use;

[0053] S13. Add ZnAl2O4 powder to purified water and perform ultrasonic treatment at a frequency of 40 to 50 kHz. After 1 to 2 hours of ultrasonic treatment, a ZnAl2O4 suspension is obtained. Dissolve zirconium nitrate in purified water under stirring and stir for 0.5 to 1 hour to obtain a zirconium nitrate solution.

[0054] S14. The zirconium nitrate solution was slowly added dropwise to the ZnAl2O4 suspension under stirring, and ammonia was slowly added dropwise after stirring for 0.5 to 1 h, and the pH value was adjusted to 9 to 10. The stirring was continued for 2 to 4 h to obtain a second mixed solution, and the molar ratio of zirconium nitrate to zinc nitrate was controlled to be (0.05 to 0.2):1;

[0055] S15. The second mixed solution is allowed to stand and age at room temperature for 12 to 15 hours, and then the supernatant is removed. The obtained solid is washed with purified water for 5 times and then dried by forced air at a drying temperature of 85 to 105°C. After drying for 12 to 14 hours, the solid is placed in a muffle furnace and calcined at 550 to 650°C for 4 to 6 hours to obtain ZrO2-ZnAl2O4, which is ground into powder for later use.

[0056] The preparation method of the modified Graphene comprises:

[0057] S21. Add graphyne powder to anhydrous ethanol and perform ultrasonic treatment at a frequency of 40 to 50 kHz. After ultrasonic treatment for 0.5 to 1 h, place in a tube furnace and dry under nitrogen protection at a temperature of 50 to 60 ° C. After drying for 12 to 14 h, obtain a graphyne intermediate and grind it into a powder for later use;

[0058] S22. Dissolve the graphyne intermediate in dimethylformamide under stirring and nitrogen protection, and heat to 75-85°C. After stirring for 0.5-1h, slowly add n-butyl lithium and copper powder, and continue stirring and reacting for 12-14h to obtain a third mixed solution, wherein the mass ratio of graphyne to n-butyl lithium is 1:(3-5);

[0059] S23. The third mixed solution is subjected to high-speed centrifugation at a speed of 10,000-12,000 rpm for 10-15 min. The separated solid is washed alternately with dimethylformamide and purified water for 5 times and then vacuum dried at a drying temperature of 55-65° C. After drying for 18-24 h, the modified graphyne is obtained and ground into powder for later use.

[0060] The modified Graphene is obtained by modifying the alkylation group on the surface of Graphene, and the particle size of the modified Graphene is 30-50 nm and the specific surface area is 450-500 m 2 / g.

[0061] The antioxidant is a compound of catechol, 2,6-di-tert-butyl-p-cresol and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], wherein the weight ratio of catechol, 2,6-di-tert-butyl-p-cresol and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is (1-2): (0.5-1): (0.2-0.4).

[0062] The heat stabilizer is a compound of zinc stearate and dibutyltin dilaurate, and the weight ratio of zinc stearate to dibutyltin dilaurate is (1-0.5): (1-1.5).

[0063] The plasticizer is one or more of dioctyl phthalate, diisononyl phthalate, calcium stearate, trimethyl phosphate and diisooctyl adipate.

[0064] The flame retardant is a compound of tin dioxide, brominated epoxy resin and sodium silicate, wherein the weight ratio of tin dioxide, brominated epoxy resin and sodium silicate is (1-2): (2-3): (5-6).

[0065] The anti-ultraviolet agent is one or more of 2-hydroxy-4-methoxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(2'-hydroxy-5'-methylphenyl).

[0066] A method for preparing a heat-resistant polyethylene material, applied to the heat-resistant polyethylene material, comprises the following steps:

[0067] S31. Ultra-high molecular weight polyethylene, antioxidant, heat stabilizer, plasticizer, flame retardant and UV inhibitor were sequentially added to a high shear mixer, and the temperature was raised to 150-180°C and heated for 2-4 hours to obtain a first mixture;

[0068] S32. The ZrO2-ZnAl2O4 and modified graphene were added to the first mixture, and the high shear mixer was started at a speed of 4000 to 4500 rpm to obtain a second mixture after running for 20 to 30 min;

[0069] S33. The second mixture is poured into an extruder for granulation, and then a corresponding mold is used in an injection molding machine to obtain a desired shape. The extrusion temperature is controlled to be 190-220°C. The extruded material is subjected to high-temperature radiation cross-linking treatment using electron beam radiation with a radiation dose of 20-30 kGy. After treatment for 10-15 minutes, a heat-resistant polyethylene material is obtained.

[0070] Example 2: This example discloses a heat-resistant polyethylene material, comprising the following raw materials in parts by weight: 70 parts of ultra-high molecular weight polyethylene, 1 part of modified graphyne, 0.5 parts of antioxidant, 0.5 parts of heat stabilizer, 1 part of plasticizer, 1 part of flame retardant, and 0.5 parts of anti-ultraviolet agent. The heat-resistant polyethylene material also includes ZrO2-ZnAl2O4, wherein the weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3:70, the particle size of ZrO2-ZnAl2O4 is 40-60 nm, and the specific surface area is 100-120 m 2 / g. The preparation method of ZrO2-ZnAl2O4 and modified graphyne in this embodiment is consistent with that in Example 1. The preparation method of a heat-resistant polyethylene material in this embodiment is consistent with that in Example 1.

[0071] Example 3: This example discloses a heat-resistant polyethylene material, comprising the following raw materials in parts by weight: 90 parts of ultra-high molecular weight polyethylene, 3 parts of modified graphyne, 2 parts of antioxidant, 2 parts of heat stabilizer, 5 parts of plasticizer, 3 parts of flame retardant, 2 parts of anti-ultraviolet agent, the heat-resistant polyethylene material also includes ZrO2-ZnAl2O4, the weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3:90, the particle size of ZrO2-ZnAl2O4 is 40-60 nm, and the specific surface area is 100-120 m 2 / g. The preparation method of ZrO2-ZnAl2O4 and modified graphyne in this embodiment is consistent with that in Example 1. The preparation method of a heat-resistant polyethylene material in this embodiment is consistent with that in Example 1.

[0072] Control group 1: The difference between this embodiment and embodiment 1 is that this embodiment does not contain ZrO2-ZnAl2O4. This embodiment discloses a heat-resistant polyethylene material, comprising the following raw materials in parts by weight: 80 parts of ultra-high molecular weight polyethylene, 2 parts of modified graphyne, 1.25 parts of antioxidant, 1.25 parts of heat stabilizer, 3 parts of plasticizer, 2 parts of flame retardant, and 1.25 parts of anti-ultraviolet agent. The preparation method of the modified graphyne of this embodiment is consistent with that of embodiment 1. The preparation method of a heat-resistant polyethylene material of this embodiment is consistent with that of embodiment 1.

[0073] Control group 2: The difference between this embodiment and embodiment 1 is that this embodiment does not contain modified graphyne. This embodiment discloses a heat-resistant polyethylene material, including the following raw materials in parts by weight: 80 parts of ultra-high molecular weight polyethylene, 1.25 parts of antioxidant, 1.25 parts of heat stabilizer, 3 parts of plasticizer, 2 parts of flame retardant, 1.25 parts of anti-ultraviolet agent, the heat-resistant polyethylene material also includes ZrO2-ZnAl2O4, the weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3:80, the particle size of ZrO2-ZnAl2O4 is 40~60 nm, and the specific surface area is 100~120 m2 / g. The preparation method of ZrO2-ZnAl2O4 in this embodiment is consistent with that in Example 1. The preparation method of a heat-resistant polyethylene material in this embodiment is consistent with that in Example 1.

[0074] Control group 3: The difference between this embodiment and embodiment 1 is that this embodiment does not contain an antioxidant. It includes the following raw materials in parts by weight: 80 parts of ultra-high molecular weight polyethylene, 2 parts of modified Graphene, 1.25 parts of thermal stabilizer, 3 parts of plasticizer, 2 parts of flame retardant, 1.25 parts of anti-ultraviolet agent, the heat-resistant polyethylene material also includes ZrO2-ZnAl2O4, the weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3:80, the particle size of ZrO2-ZnAl2O4 is 40~60 nm, and the specific surface area is 100~120m 2 / g. The preparation method of ZrO2-ZnAl2O4 and modified graphyne in this embodiment is consistent with that in Example 1. The preparation method of a heat-resistant polyethylene material in this embodiment is consistent with that in Example 1.

[0075] Control group 4: The difference between this embodiment and embodiment 1 is that this embodiment does not contain a heat stabilizer. It includes the following raw materials by weight: 80 parts of ultra-high molecular weight polyethylene, 2 parts of modified Graphene, 1.25 parts of antioxidant, 3 parts of plasticizer, 2 parts of flame retardant, 1.25 parts of anti-ultraviolet agent, the heat-resistant polyethylene material also includes ZrO2-ZnAl2O4, the weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3:80, the particle size of ZrO2-ZnAl2O4 is 40~60 nm, and the specific surface area is 100~120m 2 / g. The preparation method of ZrO2-ZnAl2O4 and modified graphyne in this embodiment is consistent with that in Example 1. The preparation method of a heat-resistant polyethylene material in this embodiment is consistent with that in Example 1.

[0076] Effect evaluation: Determination of the performance of heat-resistant polyethylene materials: (1) Heat deformation temperature test: The materials of each experimental group were made into thin sheets and heated under a constant pressure of 1.8 MPa. The deformation degree of the material at different temperatures was measured using a heat deformation temperature meter, and the deformation temperature of the materials of each experimental group was recorded; (2) Tensile performance test: The materials of each experimental group were subjected to a tensile test using a universal material testing machine at a high temperature of 100°C, and the tensile strength, elastic modulus and elongation at break of the materials of each experimental group were recorded; (3) Impact performance test: The IZOD impact testing machine was used to perform the experiment at a high temperature of 100°C, and the impact strength of the materials of each experimental group was recorded. Three parallel tests were set up for each experimental group, and the experimental results were averaged.

[0077]

[0078] Table 1 is the statistical results of the performance measurement of the heat-resistant polyethylene materials obtained in each experimental group. It can be seen from Table 1 that there are obvious differences in the performance of the heat-resistant polyethylene materials prepared in each experimental group. By comparing the performance of the heat-resistant polyethylene materials prepared in Examples 1 to 3 with those prepared in Control Groups 1 to 4, it can be found that, overall, the heat-resistant polyethylene materials prepared in Examples 1 to 3 have better performance, and the heat-resistant polyethylene material prepared in Example 1 has the best heat resistance, with a maximum heat deformation temperature of 142.5°C. The heat deformation temperature of ordinary polyethylene is usually between 60 and 90°C. A higher heat deformation temperature indicates that the material can maintain good shape and dimensional stability at high temperatures. The maximum tensile strength is 58 MPa, indicating that the material can not break or deform under a large external force. The maximum elastic modulus is 1110 MPa, indicating that the material has a small deformation and strong rigidity when subjected to force. By comparing Example 1 with Control Groups 1 to 2, it can be found that when ZrO2-ZnAl2O4 and modified graphene are added simultaneously when making the heat-resistant polyethylene material, the heat resistance of the material can be significantly improved.

[0079] Through the above experiments, the application effect of a heat-resistant polyethylene material in Example 1 of the present invention is remarkable. By optimizing the material formula, ZrO2-ZnAl2O4 and modified graphyne are added simultaneously during the production process, and combined with high-temperature radiation cross-linking treatment, the polyethylene molecular chain forms a firm three-dimensional network structure, which provides a stable matrix support for ZrO2-ZnAl2O4 and modified graphyne. The excellent chemical stability and oxidation resistance of ZrO2-ZnAl2O4 in high temperature environment effectively inhibit the thermal degradation reaction of polyethylene and extend the service life of the material. The modified graphyne helps to quickly spread heat and improve the thermal stability of the material. At the same time, its layered structure has good lubrication properties, which avoids heat accumulation and material aging caused by friction. The three form a multi-level protection system to jointly improve the thermal stability of the material.

[0080] Finally, it should be noted that: Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat-resistant polyethylene material, characterized in that: The invention comprises the following raw materials in parts by weight: 70 to 90 parts of ultra-high molecular weight polyethylene, 1 to 3 parts of modified graphene, 0.5 to 2 parts of antioxidant, 0.5 to 2 parts of heat stabilizer, 1 to 5 parts of plasticizer, 1 to 3 parts of flame retardant, and 0.5 to 2 parts of anti-ultraviolet agent; The heat-resistant polyethylene material also includes: Zirconia-zinc aluminum spinel (ZrO2-ZnAl2O4); The weight ratio of ZrO2-ZnAl2O4 to ultra-high molecular weight polyethylene is 3: (70-90); The ZrO2-ZnAl2O4 particle size is 40-60nm and the specific surface area is 100-120m 2 / g; The preparation method of ZrO2-ZnAl2O4 comprises: S11. Dissolve zinc nitrate and aluminum nitrate in purified water under stirring, control the molar ratio of zinc nitrate to aluminum nitrate to be 1:2, slowly add ammonia water dropwise after stirring for 0.5 to 1 hour, adjust the pH value to 9 to 10, continue stirring for 2 to 4 hours to obtain a first mixed solution; S12. The first mixed solution was aged at room temperature for 12 to 15 hours, and the supernatant was removed. The solid was washed with purified water five times and then dried by blast drying at a drying temperature of 85 to 105 ° C. After drying for 12 to 14 hours, it was placed in a muffle furnace at 500 to 600 ° C. and calcined for 4 to 6 hours to obtain ZnAl2O4 and ground into powder for standby use; S13. Add ZnAl2O4 powder to purified water and perform ultrasonic treatment at an ultrasonic frequency of 40 to 50 kHz. After 1 to 2 h of ultrasonic treatment, a ZnAl2O4 suspension is obtained. Dissolve zirconium nitrate in purified water under stirring and stir for 0.5 to 1 h to obtain a zirconium nitrate solution. S14. The zirconium nitrate solution was slowly added dropwise to the ZnAl2O4 suspension under stirring, and ammonia was slowly added dropwise after stirring for 0.5 to 1 h, and the pH value was adjusted to 9 to 10. After stirring for 2 to 4 h, a second mixed solution was obtained, and the molar ratio of zirconium nitrate to zinc nitrate was controlled to be (0.05 to 0.2): 1; S15. The second mixed solution was aged at room temperature for 12 to 15 hours, and then the supernatant was removed. The solid was washed with purified water five times and then dried by blast drying at a temperature of 85 to 105 ° C. After drying for 12 to 14 hours, it was placed in a muffle furnace at 550 to 650 ° C. and calcined for 4 to 6 hours to obtain ZrO2-ZnAl2O4 and ground into powder for standby use; The preparation method of the modified Graphene comprises: S21. Add graphyne powder to anhydrous ethanol and perform ultrasonic treatment at an ultrasonic frequency of 40 to 50 kHz. After ultrasonic treatment for 0.5 to 1 h, place in a tube furnace and dry under nitrogen protection at a drying temperature of 50 to 60 ° C. After drying for 12 to 14 h, a graphyne intermediate is obtained and ground into a powder for standby use; S22. The Graphene intermediate is dissolved in dimethylformamide under stirring and nitrogen protection, and the temperature is raised to 75-85° C., and after stirring for 0.5-1 h, n-butyl lithium and copper powder are slowly added, and the stirring reaction is continued for 12-14 h to obtain a third mixed solution, wherein the mass ratio of Graphene to n-butyl lithium is 1:(3-5); S23. The third mixed solution was subjected to high-speed centrifugation at a speed of 10000 to 12000 rpm for 10 to 15 min, and the separated solid was washed alternately with dimethylformamide and purified water five times and then vacuum dried at a drying temperature of 55 to 65 ° C. After drying for 18 to 24 h, the modified Graphene was obtained and ground into a powder for standby use; The modified Graphene is obtained by modifying the alkylation group on the surface of Graphene, and the particle size of the modified Graphene is 30 to 50 nm, and the specific surface area is 450 to 500 m 2 / g; Ultra-high molecular weight polyethylene cross-linked by high temperature radiation forms a polyethylene matrix, and ZrO2-ZnAl2O4 and modified graphyne are uniformly dispersed in the polyethylene matrix.

2. A heat-resistant polyethylene material according to claim 1, characterized in that: The antioxidant is a compound of catechol, 2,6-di-tert-butyl-p-cresol and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], wherein the weight ratio of catechol, 2,6-di-tert-butyl-p-cresol and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is (1-2): (0.5-1): (0.2-0.4).

3. A heat-resistant polyethylene material according to claim 1, characterized in that: The heat stabilizer is a compound of zinc stearate and dibutyltin dilaurate, and the weight ratio of zinc stearate to dibutyltin dilaurate is (1-0.5): (1-1.5).

4. A heat-resistant polyethylene material according to claim 1, characterized in that: The plasticizer is one or more of dioctyl phthalate, diisononyl phthalate, calcium stearate, trimethyl phosphate and diisooctyl adipate.

5. A heat-resistant polyethylene material according to claim 1, characterized in that: The flame retardant is a compound of tin dioxide, brominated epoxy resin and sodium silicate, wherein the weight ratio of tin dioxide, brominated epoxy resin and sodium silicate is (1-2): (2-3): (5-6).

6. A heat-resistant polyethylene material according to claim 1, characterized in that: The anti-ultraviolet agent is one or more of 2-hydroxy-4-methoxybenzoate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(2'-hydroxy-5'-methylphenyl).

7. A method for preparing a heat-resistant polyethylene material, used for preparing a heat-resistant polyethylene material as claimed in any one of claims 1 to 6, characterized in that: The method comprises the following steps: S31. Ultra-high molecular weight polyethylene, antioxidant, heat stabilizer, plasticizer, flame retardant, UV inhibitor are sequentially added to a high shear mixer, and the temperature is raised to 150-180°C, and heated for 2-4 hours to obtain a first mixture; S32. The ZrO2-ZnAl2O4 and modified graphene are added to the first mixture, and the high shear mixer is started at a speed of 4000 to 4500 rpm, and the second mixture is obtained after running for 20 to 30 min; S33. The second mixture is poured into an extruder, and the desired shape is obtained according to the corresponding mold. The extrusion temperature is controlled to be 190-220°C, and the extruded material is subjected to high-temperature radiation cross-linking treatment using electron beam radiation with a radiation dose of 20-30 kGy. After treatment for 10-15 minutes, a heat-resistant polyethylene material is obtained.

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