Polyethylene composition as well as preparation method and application thereof

Abstract

The invention relates to a polyethylene composition as well as a preparation method and application thereof, and belongs to the technical field of compositions of high-molecular compounds. The polyethylene composition disclosed by the invention is prepared from the following components in parts by weight: 74 to 100 parts of polyethylene, 0.2 to 10 parts of fluorinated elastomer, 1 to 10 parts of light aging resistant agent, 0.5 to 5 parts of lamellar inorganic filler, 0.5 to 3 parts of light screening agent, 0.1 to 0.5 part of antioxidant and 0.1 to 1 part of weather resistant agent, the light aging resistant agent is silicon dioxide immobilized hindered amine; the weather-resistant agent comprises an ultraviolet light absorber and a free radical capturing agent. The polyethylene composition can effectively improve the elongation at break attenuation after light aging and maintain good environmental stress cracking resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer composition technology, specifically to a polyethylene composition, its preparation method, and its application. Background Technology

[0002] Polyethylene (PE) possesses excellent chemical stability, high toughness, good electrical insulation, and processing properties, making it widely used in cable sheathing, electronic component packaging, pipes, and packaging materials. However, PE is susceptible to photoaging under prolonged outdoor exposure, leading to a significant decrease in its elongation at break. While adding UV-resistant agents can improve PE's resistance to photoaging, these agents are prone to migration and consumption in humid and hot environments (such as spraying), making it difficult to effectively improve the service life of PE materials. Furthermore, photoaging also affects PE crosslinking, post-crystallization, and molecular chain degradation, thereby increasing the risk of stress cracking in PE materials. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a polyethylene composition, its preparation method, and its application.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a polyethylene composition comprising, by weight, the following components: 74-100 parts polyethylene, 0.2-10 parts fluorinated elastomer, 1-10 parts photoaging resistant agent, 0.5-5 parts lamellar inorganic filler, 0.5-3 parts light shielding agent, 0.1-0.5 parts antioxidant, and 0.1-1 parts weather resistant agent; The photo-aging resistant agent is a silica-supported hindered amine, which includes silica, silane coupling agent and hindered amine; The weather-resistant agent includes ultraviolet light absorbers and free radical scavengers.

[0005] This invention uses polyethylene as the base resin and introduces fluorinated elastomers to reduce the crystallinity of polyethylene. This promotes the absorption and dispersion of local stress, thereby suppressing stress concentration at the interface between crystalline and amorphous regions, and reducing the generation and propagation of microcracks during aging. The fluorine in the fluorinated elastomers is used to improve hydrophobicity and oleophobicity, reducing the deterioration of the polyethylene composition's properties caused by the spraying environment. Simultaneously, combined with silica-supported hindered amines, this invention synergistically inhibits the extraction of antioxidants and weathering agents by the spraying environment, while also bonding or adsorbing the hindered amines onto the surface of silica particles. It can reduce the migration or volatilization of hindered amines and promote the uniform distribution of the active sites of hindered amines in the polyethylene matrix, thereby achieving high free radical capture efficiency under long-term aging conditions; while weathering agents and light shielding agents containing ultraviolet light absorbers and free radical scavengers can form a multi-layered light stabilizing effect, and synergistically construct a "shielding-absorption-capture" triple defense system with hindered amines; the combination of layered inorganic fillers and antioxidants can effectively inhibit thermal oxidation and block oxygen; the synergistic effect of each component can effectively inhibit the decrease in elongation at break of polyethylene composition after photoaging and maintain its good resistance to environmental stress cracking.

[0006] In the polyethylene composition of the present invention, polyethylene is the base resin, and the mass percentage of polyethylene is ≥45% based on the total mass of the polyethylene composition; the fluorinated elastomer is a copolymer (PFE) type elastomer with tetrafluoroethylene (TFE) and perfluoroethylene ether (PFVE) as the main monomers.

[0007] In some embodiments, the particle size D50 of the silica in the silica-supported hindered amine is from 1 μm to 10 μm, for example, it can be, but is not limited to, any or both of the following values: 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm. The particle size D50 of the silica can be determined with reference to GB / T 19077.1-2008 "Particle Size Analysis by Laser Diffraction".

[0008] In some embodiments, the weight parts of polyethylene in the polyethylene composition may specifically be, but are not limited to, any or both of the following ranges: 74 parts, 75 parts, 76 parts, 78 parts, 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, 90 parts, 92 parts, 94 parts, 96 parts, 98 parts, and 100 parts.

[0009] In some embodiments, the weight parts of the fluorinated elastomer in the polyethylene composition may specifically be, but are not limited to, any one or any two of the following values: 0.2 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, and 10 parts.

[0010] In some embodiments, the weight parts of the photo-aging resistant agent in the polyethylene composition may be, but are not limited to, any one or any two of the following: 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, and 10 parts.

[0011] In some embodiments, the weight parts of the lamellar inorganic filler in the polyethylene composition may be, but are not limited to, any one or any two of the following: 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, and 5 parts.

[0012] In some embodiments, the weight parts of the light-shielding agent in the polyethylene composition may be, but are not limited to, any one or any two of the following values: 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, and 3 parts.

[0013] In some embodiments, the weight parts of the antioxidant in the polyethylene composition may specifically be, but are not limited to, any one or any two of the following values: 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, and 0.5 parts.

[0014] In some embodiments, the weight parts of the weathering agent in the polyethylene composition may be, but are not limited to, any one or any two of the following values: 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, and 1 part.

[0015] In some embodiments, polyethylene includes at least one of high-density polyethylene, low-density polyethylene, and linear low-density polyethylene.

[0016] In some embodiments, the antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), and pentaerythritol tetrakis-3-lauryl thiopropionate (antioxidant 412S).

[0017] In a preferred embodiment of the polyethylene composition of the present invention, the hindered amine in the photo-aging resistant agent has a mass fraction of 10% to 30% relative to silica, for example, but not limited to, any or both of the following ranges: 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 23%, 22%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%. When the mass fraction of the hindered amine in the photo-aging resistant agent is within the above range, the hindered amine can be more uniformly anchored on the surface of silica particles, thereby better ensuring a high density of active sites to enhance the reaction rate and capture efficiency against free radicals, thus more effectively protecting the polyethylene molecular chains and better maintaining the elongation at break of the polyethylene composition after aging.

[0018] In some embodiments, the hindered amine is a hindered amine compound containing an NH, NR (where R is an alkane chain) or NOR (where R is an alkane chain) structure, including, but not limited to, at least one of poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) ester, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, saturated fatty acid, and 2,2,6,6-tetramethyl-4-piperidinyl ester.

[0019] In a preferred embodiment of the polyethylene composition of the present invention, the mass fraction of the silane coupling agent in the photo-aging resistant agent relative to silica is 5% to 20%, for example, but not limited to any one or both of the following ranges: 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 15%, 16%, 17%, 18%, 19%, and 20%. The silane coupling agent is located on at least a portion of the surface of silica, promoting uniform dispersion of silica-supported hindered amines in the polyethylene matrix while also enhancing the stability of the supported hindered amines, thereby better inhibiting migration or volatilization of the hindered amines during long-term use. When the mass fraction of the silane coupling agent relative to silica in the photo-aging resistant agent is within the above range, it not only further improves the compatibility of silica-supported hindered amines with polyethylene and their dispersion in polyethylene, but also ensures that the hindered amines are firmly anchored to silica to achieve better anti-migration and anti-volatilization properties.

[0020] In some embodiments, the silane coupling agent includes, but is not limited to, at least one of vinyl silane coupling agents, amino silane coupling agents, epoxy silane coupling agents, mercapto silane coupling agents, and methacryloxy silane coupling agents.

[0021] In a preferred embodiment of the polyethylene composition of the present invention, the silica-supported hindered amine is prepared by the following method: (1) Modify the surface of silica with a silane coupling agent to obtain modified silica; (2) The modified silica is reacted with a hindered amine to obtain silica-supported hindered amine.

[0022] Preferably, the silica, silane coupling agent and organic solvent are mixed evenly and then refluxed at high temperature to obtain modified silica; more preferably, the organic solvent is toluene, and the high temperature reflux is refluxed at 90°C to 110°C for 2 to 4 hours.

[0023] Preferably, the modified silica, hindered amine and organic solvent are mixed evenly and reacted at 55°C to 75°C for 4 to 6 hours to obtain silica-supported hindered amine.

[0024] In a preferred embodiment of the polyethylene composition of the present invention, the mass ratio of the ultraviolet absorber to the free radical scavenger is 1:0.8 to 1:1.2, preferably 1:0.9 to 1:1.1, and more preferably 1:1.

[0025] In some embodiments, the ultraviolet absorber includes, but is not limited to, at least one of benzotriazoles, benzophenones, and triazines.

[0026] In some embodiments, the free radical scavenger is preferably a hindered amine light stabilizer, including, but not limited to, at least one of UV-2020 (CAS No. 192268-64-7), UV-944 (CAS No. 70624-18-9), and UV-622 (CAS No. 65447-77-0).

[0027] In a preferred embodiment of the polyethylene composition of the present invention, the polyethylene composition further includes hydrogenated petroleum resin. The hydrogenated petroleum resin is a low molecular weight saturated hydrocarbon resin, which is compatible with polyethylene and can fill the free volume of the amorphous regions of polyethylene, reducing oxygen diffusion channels, thereby reducing oxygen permeability, improving the gas barrier properties of the polyethylene composition, and further improving the aging resistance of the polyethylene composition.

[0028] In a preferred embodiment of the polyethylene composition of the present invention, the mass ratio of the hydrogenated petroleum resin to the lamellar inorganic filler is 1:2 to 1:10, for example, but not limited to any one or both of the following: 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, and 1:10. When the mass ratio of the hydrogenated petroleum resin to the lamellar inorganic filler is within the above range, the hydrogenated petroleum resin and the lamellar inorganic filler can work synergistically better. This not only facilitates the formation of tortuous paths by the lamellar inorganic filler in the polyethylene matrix to prolong the diffusion path of oxygen molecules and reduce oxygen permeability, but also restricts the movement of molecular chains in the interfacial region of polyethylene to form a low-permeability zone, thereby significantly improving the gas barrier properties of the polyethylene composition and enhancing its aging resistance.

[0029] As a preferred embodiment of the polyethylene composition of the present invention, the polyethylene has a melt mass flow rate of 0.1 g / 10 min to 10 g / 10 min at 190°C and 2.16 kg (test standard is ISO 1133-1-2011), for example, but not limited to any one or any two of the following values: 0.1 g / 10 min, 0.2 g / 10 min, 0.4 g / 10 min, 0.6 g / 10 min, 0.8 g / 10 min, 1 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, and 10 g / 10 min.

[0030] In a preferred embodiment of the polyethylene composition of the present invention, the layered inorganic filler includes at least one of montmorillonite, magnesium hydroxide, and hydrotalcite, preferably montmorillonite. The particle size D50 of the layered inorganic filler can be determined with reference to GB / T19077.1-2008 "Particle Size Analysis by Laser Diffraction".

[0031] In some embodiments, the particle size D50 of the lamellar inorganic filler is from 2 μm to 22 μm, for example, but not limited to any or both of the following values: 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm.

[0032] In some embodiments, the lamellar inorganic filler is composed of at least two lamellar inorganic fillers with different particle sizes D50; preferably, the lamellar inorganic filler is composed of montmorillonite A with a particle size D50 of 15 μm to 17 μm and montmorillonite B with a particle size D50 of 19 μm to 21 μm; the mass ratio of montmorillonite A to montmorillonite B is 1:3 to 3:1, for example, but not limited to any one or both of 1:3, 1:2, 1:1, 2:1, and 3:1.

[0033] In a preferred embodiment of the polyethylene composition of the present invention, the light-shielding agent includes at least one of carbon black, titanium dioxide, zinc oxide, and cerium oxide.

[0034] In some embodiments, the titanium dioxide includes at least one of rutile titanium dioxide and anatase titanium dioxide, preferably rutile titanium dioxide.

[0035] In a preferred embodiment of the polyethylene composition of the present invention, the polyethylene composition further comprises 0.1 to 1 part by weight of a lubricant.

[0036] In some embodiments, the weight parts of lubricant in the polyethylene composition may specifically be, but are not limited to, any one or any two of the following values: 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, and 1 part.

[0037] In some embodiments, the lubricant includes, but is not limited to, at least one of erucamide, oleamide, EBS amides, PE wax, stearate, and pentaerythritol stearate.

[0038] Secondly, the present invention provides a method for preparing the above-mentioned polyethylene composition, comprising the following steps: uniformly mixing the components and melting and extruding to obtain a polyethylene composition.

[0039] Specifically, in the above preparation method, a twin-screw extruder can be used for melt extrusion, with a melt extrusion temperature of 160°C to 190°C and a screw speed of 400 rpm to 600 rpm.

[0040] Thirdly, the present invention provides an application of the above-mentioned polyethylene composition in the preparation of cable sheaths, electronic component encapsulation, pipes, and packaging materials.

[0041] Fourthly, the present invention provides an article made of the above-described polyethylene composition.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses polyethylene as the base resin and introduces fluorinated elastomers to reduce the crystallinity of polyethylene. This promotes the absorption and dispersion of local stress, thereby suppressing stress concentration at the interface between crystalline and amorphous regions, and reducing the generation and propagation of microcracks during aging. The fluorine in the fluorinated elastomers is used to improve hydrophobicity and oleophobicity, reducing the deterioration of the polyethylene composition's properties caused by the spraying environment. Simultaneously, combined with silica-supported hindered amines, this invention synergistically inhibits the extraction of antioxidants and weathering agents by the spraying environment, while also bonding or adsorbing the hindered amines onto the surface of silica particles. It can reduce the migration or volatilization of hindered amines and promote the uniform distribution of the active sites of hindered amines in the polyethylene matrix, thereby achieving high free radical capture efficiency under long-term aging conditions; while weathering agents and light shielding agents containing ultraviolet light absorbers and free radical scavengers can form a multi-layered light stabilizing effect, and synergistically construct a "shielding-absorption-capture" triple defense system with hindered amines; the combination of layered inorganic fillers and antioxidants can effectively inhibit thermal oxidation and block oxygen; the synergistic effect of each component can effectively inhibit the decrease in elongation at break of polyethylene composition after photoaging and maintain its good resistance to environmental stress cracking. Detailed Implementation

[0043] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0044] Unless otherwise specified, all other materials, reagents, etc. used in the examples and comparative examples are commercially available.

[0045] 1. Raw materials and reagents 1) Polyethylene Polyethylene 1, melt flow rate of 1g / 10min, grade HDPE 5000S, manufacturer: China National Petroleum Corporation; Polyethylene 2, melt flow rate of 8 g / 10 min, grade HDPE DMDA8008, manufacturer: China National Petroleum Corporation; Polyethylene 3, melt flow rate of 2 g / 10 min, grade LLDPE 7042 (Mao), China Petroleum & Chemical Corporation.

[0046] 2) Elastomers Fluorinated elastomer 1, grade PFE 60, manufacturer 3M; Fluorinated elastomer 2, grade PFE 132TB, manufacturer 3M; POE elastomer, grade POE 8137, manufactured by Dow Chemical.

[0047] 3) Light aging resistant agent Silica 1, with a particle size D50 of 2μm, is commercially available; Silica 2, with a particle size D50 of 4μm, is commercially available; Silane coupling agent 1 is an epoxy silane coupling agent (KH-560), commercially available; Silane coupling agent 2 is a vinylsilane coupling agent (A-171), commercially available; Hindered amine 1 is poly(4-hydroxyethyl-2,2,6,6-tetramethyl-1-piperidinol) ester, brand name UV-622, commercially available; Hindered amine 2 is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, brand name UV-770, commercially available; Hindered phenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], commercially available.

[0048] Table 1. Weight parts of each component in photoaging resistant agents 1 to 9 In Table 1, " / " indicates that there are no relevant parameters.

[0049] Photoaging resistant agents 1 to 9 are prepared by the following method: vacuum-dried silica is added to toluene solvent, ultrasonically dispersed, and then a silane coupling agent is added. The mixture is stirred and refluxed at 100°C for 3 hours. After the reaction is completed, it is extracted with acetone and vacuum dried at 75°C for 24 hours to obtain modified silica. Then, the modified silica and hindered amine (or hindered phenol) are added to tetrahydrofuran and stirred at 65°C for 5 hours. After drying, the photoaging resistant agent is obtained.

[0050] 4) Lamellar inorganic fillers and hydrogenated petroleum resin Montmorillonite 1, with a particle size D50 of 16μm, grade I.44P, manufactured by Beijing Yiwei Special Chemical Technology Development Co., Ltd. Montmorillonite 2, with a particle size D50 of 20μm, grade I.30P, manufactured by Beijing Yiwei Special Chemical Technology Development Co., Ltd. Magnesium hydroxide, particle size D50 is 3.5μm, grade 2500-G, manufacturer: Yingkou Hangsheng Technology Industry Co., Ltd. Hydrogenated petroleum resin, grade H-142W, manufacturer Eastman.

[0051] 5) Light shielding agent Titanium dioxide 1, particle size D50 is 0.22μm, grade R-103, manufacturer Chemours; Titanium dioxide 2, particle size D50 is 0.35μm, grade R-960, manufacturer Chemours; Carbon black, grade M717, manufacturer Cabot.

[0052] 6) Antioxidants The antioxidant is obtained by compounding antioxidant 1010 (commercially available) and antioxidant 168 (commercially available) in a certain mass ratio.

[0053] 7) Weather resistant agent Weather resistant agent 1 is 2-hydroxy-4-n-octyloxybenzophenone, brand name UV-531, commercially available; Weathering agent 2 is a hindered amine light stabilizer, brand name UV-2020, commercially available; Weather resistant agent 3 is 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxy-phenol, brand name UV-1577, commercially available.

[0054] 6) Lubricant The lubricant is calcium stearate, which is commercially available.

[0055] 2. Preparation method of the polyethylene composition of the present invention According to the formula, the components are mixed and then added to a twin-screw extruder for melt extrusion to obtain a polyethylene composition; wherein the temperature range of the twin-screw extruder is 160℃ to 190℃ and the screw speed is 500 rpm.

[0056] 3. Performance Testing 1) Light aging resistance test According to standard ISO 527-1-2019, the polyethylene compositions in each example and comparative example were injection molded into tensile test strips with a thickness of 1 mm. The tensile test strips of each example or comparative example were randomly divided into two groups, A and B. Group A was directly subjected to tensile testing (tensile rate of 50 mm / min) to obtain the initial elongation at break 'a'. Group B was first subjected to a light aging test (irradiation wavelength of 280 nm to 400 nm, irradiation intensity of 300 W / m). 2 After a cumulative irradiation dose of 300 kWh, a tensile test was performed (tensile rate of 50 mm / min) to obtain the elongation at break after aging, b; the elongation at break retention rate = b / a × 100%.

[0057] 2) Environmental stress cracking resistance test The polyethylene compositions in each embodiment and comparative example were made into specimens with dimensions of 38mm×13mm×3mm. The specimens were inserted into the groove of the bending fixture and bent into a U-shape. The test was conducted according to GB / T 1842-2008 "Environmental Stress Cracking Test Method for Polyethylene". The surface cracking was recorded after 500 hours of bending treatment. If no cracking occurred, it was recorded as "passed"; if cracking occurred, it was recorded as "failed".

[0058] Table 2 shows the weight parts and properties of each component in the polyethylene compositions of Examples 1 to 9. Table 3 shows the weight parts and properties of each component in the polyethylene compositions of Examples 10 to 18. Table 4 shows the weight parts and properties of each component in the polyethylene compositions of each comparative example. In Tables 2, 3 and 4, “ / ” indicates that there are no relevant parameters. In Table 4, “Silica 1 + Silane Coupling Agent 1 + Hindered Amine 1” means that a physical mixture of silica 1, silane coupling agent 1 and hindered amine 1 is directly added, and the mass ratio of silica 1, silane coupling agent 1 and hindered amine 1 is 100:15:20.

[0059] According to the data in Tables 2 to 4, the initial elongation at break of the polyethylene compositions in Examples 1 to 18 was all above 563%, and the elongation at break retention rate after the light aging test was all above 78%. At the same time, they all passed the stress cracking resistance test (500h), indicating that the polyethylene compositions of the present invention can effectively improve the attenuation of elongation at break after light aging and maintain good environmental stress cracking resistance.

[0060] As can be seen from Examples 1, 1, and 2, when the photo-aging agent lacks a silane coupling agent or a hindered amine, although it has little effect on the initial elongation at break and stress crack resistance of the polyethylene composition, it cannot effectively improve the attenuation of elongation at break after photo-aging, resulting in a significant reduction in the elongation at break retention rate. Meanwhile, as can be seen from Comparative Examples 3 and 4, using only UV absorbers or free radical scavengers as weathering agents is also difficult to effectively inhibit the attenuation of elongation at break of the polyethylene composition after photo-aging. Furthermore, as can be seen from Comparative Examples 5 and 6, the lack of fluorinated elastomers not only significantly reduces the elongation at break retention rate of the polyethylene composition after photo-aging but also significantly deteriorates its stress crack resistance. The lack of a photo-aging agent leads to a significant reduction in the elongation at break retention rate of the polyethylene composition after photo-aging. As can be seen from Comparative Example 7, directly adding a physical mixture of silica 1, silane coupling agent 1, and hindered amine 1 makes it difficult to exert the synergistic effect of the three and effectively improve the elongation at break retention rate of the polyethylene composition after photo-aging.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polyethylene composition, characterized in that, By weight, it includes the following components: Polyethylene 74-100 parts, fluorinated elastomer 0.2-10 parts, light aging resistant agent 1-10 parts, lamellar inorganic filler 0.5-5 parts, light shielding agent 0.5-3 parts, antioxidant 0.1-0.5 parts, weather resistant agent 0.1-1 parts; The photo-aging resistant agent is a silica-supported hindered amine, which includes silica, silane coupling agent and hindered amine; The weather-resistant agent includes ultraviolet light absorbers and free radical scavengers.

2. The polyethylene composition according to claim 1, characterized in that, The hindered amine in the photo-aging resistant agent has a mass fraction of 10% to 30% relative to silica.

3. The polyethylene composition according to claim 1, characterized in that, The silane coupling agent in the photo-aging resistant agent has a mass fraction of 5% to 20% relative to silica.

4. The polyethylene composition according to claim 1, characterized in that, The mass ratio of the ultraviolet absorber to the free radical scavenger is from 1:0.8 to 1:1.

2.

5. The polyethylene composition according to claim 1, characterized in that, The polyethylene composition also includes hydrogenated petroleum resin, wherein the mass ratio of the hydrogenated petroleum resin to the layered inorganic filler is 1:2 to 1:

10.

6. The polyethylene composition according to claim 1, characterized in that, The melt flow rate of the polyethylene at 190°C and 2.16 kg is 0.1 g / 10 min to 10 g / 10 min.

7. The polyethylene composition according to claim 1, characterized in that, The lamellar inorganic filler includes at least one of montmorillonite, magnesium hydroxide, and hydrotalcite; and / or, the light shielding agent includes at least one of carbon black, titanium dioxide, zinc oxide, and cerium oxide.

8. A method for preparing the polyethylene composition according to any one of claims 1 to 7, characterized in that, Includes the following steps: The components are mixed evenly and melt-extruded to obtain a polyethylene composition.

9. The use of the polyethylene composition according to any one of claims 1 to 7 in the preparation of cable sheaths, electronic component encapsulations, pipes, and packaging materials.

10. A component, characterized in that, Made from the polyethylene composition according to any one of claims 1 to 7.

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