CN117467056A - Polyethylene powder, preparation and application thereof, and method for improving wear resistance of polyethylene product - Google Patents
Polyethylene powder, preparation and application thereof, and method for improving wear resistance of polyethylene product Download PDFInfo
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- CN117467056A CN117467056A CN202311415130.7A CN202311415130A CN117467056A CN 117467056 A CN117467056 A CN 117467056A CN 202311415130 A CN202311415130 A CN 202311415130A CN 117467056 A CN117467056 A CN 117467056A
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- polyethylene
- polyethylene powder
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- -1 Polyethylene Polymers 0.000 title claims abstract description 119
- 239000004698 Polyethylene Substances 0.000 title claims abstract description 116
- 229920000573 polyethylene Polymers 0.000 title claims abstract description 116
- 239000000843 powder Substances 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 239000003054 catalyst Substances 0.000 claims abstract description 35
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000009826 distribution Methods 0.000 claims abstract description 9
- 230000000694 effects Effects 0.000 claims abstract description 7
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 30
- 239000005977 Ethylene Substances 0.000 claims description 30
- 238000012545 processing Methods 0.000 claims description 23
- 238000001125 extrusion Methods 0.000 claims description 20
- 238000006116 polymerization reaction Methods 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 17
- 239000003963 antioxidant agent Substances 0.000 claims description 16
- 238000001175 rotational moulding Methods 0.000 claims description 14
- 230000003078 antioxidant effect Effects 0.000 claims description 13
- 238000000465 moulding Methods 0.000 claims description 13
- VOITXYVAKOUIBA-UHFFFAOYSA-N triethylaluminium Chemical group CC[Al](CC)CC VOITXYVAKOUIBA-UHFFFAOYSA-N 0.000 claims description 13
- 239000001257 hydrogen Substances 0.000 claims description 11
- 229910052739 hydrogen Inorganic materials 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- CPOFMOWDMVWCLF-UHFFFAOYSA-N methyl(oxo)alumane Chemical compound C[Al]=O CPOFMOWDMVWCLF-UHFFFAOYSA-N 0.000 claims description 10
- 229910052723 transition metal Inorganic materials 0.000 claims description 8
- 150000003624 transition metals Chemical class 0.000 claims description 8
- 238000000071 blow moulding Methods 0.000 claims description 7
- 239000000155 melt Substances 0.000 claims description 7
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 claims description 5
- 239000000314 lubricant Substances 0.000 claims description 5
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 claims description 4
- IAQRGUVFOMOMEM-UHFFFAOYSA-N butene Natural products CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 claims description 4
- 238000010101 extrusion blow moulding Methods 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 239000012968 metallocene catalyst Substances 0.000 claims description 4
- MCULRUJILOGHCJ-UHFFFAOYSA-N triisobutylaluminium Chemical compound CC(C)C[Al](CC(C)C)CC(C)C MCULRUJILOGHCJ-UHFFFAOYSA-N 0.000 claims description 4
- 238000007731 hot pressing Methods 0.000 claims description 3
- 238000009700 powder processing Methods 0.000 claims description 3
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 3
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 3
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 claims description 2
- 239000000654 additive Substances 0.000 claims 2
- 239000006082 mold release agent Substances 0.000 claims 2
- 239000011261 inert gas Substances 0.000 claims 1
- 238000012360 testing method Methods 0.000 abstract description 7
- 238000000227 grinding Methods 0.000 abstract description 2
- 239000004570 mortar (masonry) Substances 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 49
- 239000000047 product Substances 0.000 description 43
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 40
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 31
- 229910052757 nitrogen Inorganic materials 0.000 description 20
- 239000007789 gas Substances 0.000 description 19
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 description 18
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 description 18
- 238000005299 abrasion Methods 0.000 description 14
- 238000003756 stirring Methods 0.000 description 14
- 238000001816 cooling Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 239000000498 cooling water Substances 0.000 description 6
- 239000000178 monomer Substances 0.000 description 6
- 239000012752 auxiliary agent Substances 0.000 description 5
- 239000007822 coupling agent Substances 0.000 description 5
- 238000004132 cross linking Methods 0.000 description 5
- 239000003431 cross linking reagent Substances 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- MGWAVDBGNNKXQV-UHFFFAOYSA-N diisobutyl phthalate Chemical compound CC(C)COC(=O)C1=CC=CC=C1C(=O)OCC(C)C MGWAVDBGNNKXQV-UHFFFAOYSA-N 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 239000011256 inorganic filler Substances 0.000 description 4
- 229910003475 inorganic filler Inorganic materials 0.000 description 4
- 229920000092 linear low density polyethylene Polymers 0.000 description 4
- 239000004707 linear low-density polyethylene Substances 0.000 description 4
- 238000004381 surface treatment Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 3
- 229920013716 polyethylene resin Polymers 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 3
- 235000021355 Stearic acid Nutrition 0.000 description 2
- BGYHLZZASRKEJE-UHFFFAOYSA-N [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxy]-2,2-bis[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxymethyl]propyl] 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate Chemical compound CC(C)(C)C1=C(O)C(C(C)(C)C)=CC(CCC(=O)OCC(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)=C1 BGYHLZZASRKEJE-UHFFFAOYSA-N 0.000 description 2
- 239000002216 antistatic agent Substances 0.000 description 2
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 description 2
- 239000008116 calcium stearate Substances 0.000 description 2
- 235000013539 calcium stearate Nutrition 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000000748 compression moulding Methods 0.000 description 2
- 238000005094 computer simulation Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- NKSJNEHGWDZZQF-UHFFFAOYSA-N ethenyl(trimethoxy)silane Chemical compound CO[Si](OC)(OC)C=C NKSJNEHGWDZZQF-UHFFFAOYSA-N 0.000 description 2
- 229920001973 fluoroelastomer Polymers 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Natural products C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 2
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 2
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 2
- SSDSCDGVMJFTEQ-UHFFFAOYSA-N octadecyl 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate Chemical compound CCCCCCCCCCCCCCCCCCOC(=O)CCC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 SSDSCDGVMJFTEQ-UHFFFAOYSA-N 0.000 description 2
- 239000012005 post-metallocene catalyst Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000008117 stearic acid Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- BIKXLKXABVUSMH-UHFFFAOYSA-N trizinc;diborate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]B([O-])[O-].[O-]B([O-])[O-] BIKXLKXABVUSMH-UHFFFAOYSA-N 0.000 description 2
- KOMNUTZXSVSERR-UHFFFAOYSA-N 1,3,5-tris(prop-2-enyl)-1,3,5-triazinane-2,4,6-trione Chemical compound C=CCN1C(=O)N(CC=C)C(=O)N(CC=C)C1=O KOMNUTZXSVSERR-UHFFFAOYSA-N 0.000 description 1
- 239000004712 Metallocene polyethylene (PE-MC) Substances 0.000 description 1
- 239000002262 Schiff base Substances 0.000 description 1
- 150000004753 Schiff bases Chemical class 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000012612 commercial material Substances 0.000 description 1
- 229920003020 cross-linked polyethylene Polymers 0.000 description 1
- 239000004703 cross-linked polyethylene Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 1
- 235000012438 extruded product Nutrition 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 229920001903 high density polyethylene Polymers 0.000 description 1
- 239000004700 high-density polyethylene Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000010128 melt processing Methods 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 238000006902 nitrogenation reaction Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- VPGLGRNSAYHXPY-UHFFFAOYSA-L zirconium(2+);dichloride Chemical compound Cl[Zr]Cl VPGLGRNSAYHXPY-UHFFFAOYSA-L 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
- C08K5/098—Metal salts of carboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/13—Phenols; Phenolates
- C08K5/134—Phenols containing ester groups
- C08K5/1345—Carboxylic esters of phenolcarboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/08—Copolymers of ethene
- C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
- C08L23/0815—Copolymers of ethene with aliphatic 1-olefins
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
The invention relates to a polyethylene powder, a preparation method and an application thereof, and a method for improving the wear resistance of polyethylene products, wherein the polyethylene powder is prepared by adopting a single-activity catalyst, the weight average molecular weight is 20 ten thousand-100 ten thousand, the molecular weight distribution Mw/Mn is less than or equal to 3.5, and the thousands of carbon short-chain branch number SCB is 1-80; the powder is prepared to obtain the entanglement degree C of the product under 21.6kg load and 190 ℃ with melt index MI of 0.01-20g/10min tan Can reach more than 10 percent. The average wear rate of the polyethylene product prepared by using the polyethylene powder disclosed by the invention is lower than 3.0% through a mortar grinding test, and the polyethylene product can be applied to the field with certain requirements on wear resistance.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and relates to polyethylene powder, a preparation method and an application thereof, and a method for improving wear resistance of a polyethylene product.
Background
With the rapid development of science and technology, the engineering technology world has certain requirements on the wear resistance of materials, and wear-resistant products can improve the service life of the products and endow the products with more excellent properties. At present, the wear resistance of the conventional polyethylene material is poor, and in order to enable the polyolefin material to have enough wear resistance, a great deal of literature and patents are available for enhancing the wear resistance of the polyethylene material by using some means.
The first most common method is to use ultra-high molecular weight polyethylene to replace polyethylene for preparing products, wherein the ultra-high molecular weight polyethylene has extremely excellent wear resistance and other excellent mechanical properties, but the processing is very difficult due to the large entanglement degree of molecular chains in the processing aspect, and conventional polyethylene processing equipment cannot process the ultra-high molecular weight polyethylene. The ultra-high molecular weight polyethylene can only be prepared into wear-resistant plates through hot pressing, if other sectional materials are to be obtained, the wear-resistant plates can be further processed after being blended and modified with HDPE and other auxiliary agents, and the processing efficiency is low, such as Chinese patent patents CN20201148416. X, CN201811178229.9, CN111320797B and the like.
The second type is to crosslink polyethylene, increase entanglement degree of polyethylene molecular chain and improve wear resistance of polyethylene. The crosslinking means can be mainly divided into two forms of adding a crosslinking agent in the extrusion process and directly crosslinking the surface of the product, such as Chinese patent No. CN112770789B, CN113045810B and the like. The method has certain limitation on the processing technology and the processed product, and meanwhile, the blending and crosslinking working section is additionally added, so that the surface crosslinking production efficiency is lower, and the overall cost is higher.
The third category is to add inorganic nano particles into polyethylene to improve the wear resistance of the surface of polyethylene products, such as the Chinese patent No. CN113045810B, CN 103756088B. The method can improve the wear resistance of the material to a certain extent, but the added filler needs to be subjected to compatibility treatment in advance, so that the cost is high, and the mechanical property of the final product can be influenced.
The fourth category is to combine the above methods, for example, such as mixing inorganic particles of a crosslinking agent into polyethylene, further crosslinking of ultra-high molecular weight polyethylene, or mixing ultra-high molecular weight polyethylene and an inorganic filler into polyethylene, for example, U.S. Pat. No. 3,979B 2, and Chinese patent No. 113980160B, CN102492213B, CN101463156B, CN 101735505B. The products prepared by the method are all oriented to occasions with extremely high wear resistance, and the products have high production cost and great difficulty, but can form better wear resistance.
Among the four means for improving the wear resistance of the polyethylene, the first means is to improve the wear resistance of the product by improving the structure of a polyethylene molecular chain, and the other three means are to improve the wear resistance of the polyethylene resin by modifying or processing the polyethylene resin. The improvement of the wear resistance of the three products depends in part on the modification and process improvement effects, and in part on the molecular chain structure of the processed resin raw material. Therefore, it is critical to be able to obtain polyethylene resins having abrasion resistant properties in their own right.
The first means is to obtain ultra-high molecular weight polyethylene by polymerization means, and although the wear resistance of the obtained resin product is greatly improved, the processability is greatly restricted, and when extrusion, rotational molding, blow molding and other processing and molding are carried out, the fluidity of the resin is required to be modified, so that the complexity and cost of product processing are greatly increased.
Disclosure of Invention
The invention aims to provide polyethylene powder, and preparation and application thereof, so as to solve the problems that the wear resistance of the existing polyethylene product is insufficient, particularly when the wear resistance of the product obtained by processing polyethylene through means such as extrusion, rotational molding, blow molding and the like is insufficient, the wear resistance of the product needs to be improved through means of modification or process improvement, and the product can be applied to the field with higher requirements on part of wear resistance.
The aim of the invention can be achieved by the following technical scheme:
one of the technical schemes of the invention provides polyethylene powder which is prepared by adopting a single-activity catalyst, wherein the weight average molecular weight is 20-100 ten thousand, the molecular weight distribution Mw/Mn is less than or equal to 3.5, and the thousands of carbon short-chain branch number SCB is 1-80; the melt index MI is 0.01-20g/10min at 190 ℃ under 21.6kg load. Degree of entanglement C of articles made from such polyethylene powder tan Can reach more than 10 percent.
Further, the single-activity catalyst is a metallocene catalyst or a transition metal catalyst. Such as a metallocene catalyst of tetramethyl cyclopentadiene zirconium dichloride (TMCP), a Schiff base single-site catalyst of bis [ N-cyclohexyl- (3-t-butylsalicylaldimine) ] zirconium dichloride (FI), an ActivCAT catalyst produced by GRACE company, a Post-metallocene catalyst of new generation developed and researched by Sanjing chemical company, japan and Dow chemical company.
The team of the invention carries out deep analysis on the molecular chain structure of polyethylene, and discovers that the entanglement degree of the molecular chain has great relevance with the wear resistance of the polyethylene. According to the characterization means of the entanglement degree of the polyethylene in the invention patent ZL201811419650.4, the calculated entanglement degree of the polyethylene product in the invention is set as C tan The team of the invention further prepares entanglement degree C of the ultra-high molecular weight polyethylene, the low molecular weight polyethylene and the polyethylene with the structure of the invention into the plate product tan The value is analyzed, and C of the plate product is obtained through calculation and simulation calculation tan The values are shown in FIG. 1 as a function of the molecular weight Mw and the molecular weight distribution Mw/Mw. From the figure, C can be found tan The value can be determined by color, C when Mw is low tan The value gradient separation direction is arrow 2, at this time, the C of the polyethylene plate tan The value is significantly affected by the molecular weight, whereas when the molecular weight is large, C tan The value separation direction gradually deviates to arrow 1 to illustrate C of the polyethylene plate tan The values are greatly affected by the molecular weight distribution. Based on the characteristics, the team screens C through computer simulation tan The Mw value is equivalent to 100 ten thousand ultra-high molecular weight polyethylene, but the Mw value is lower than 100 ten thousand, the corresponding Mw/Mn characteristic is obtained in the region, and the corresponding polyethylene molecular chain structure type is determined.
After the structure type of the polyethylene is confirmed, the polyethylene powder corresponding to the molecular chain structure of the computer simulation result is obtained by the team of the invention through a laboratory ethylene polymerization means, and the powder is processed into a corresponding polyethylene product through a post-processing technology. Surprisingly, it was found that C by testing the abrasion resistance of the respective articles tan The value has better correlation with the wear resistance of the polyethylene product, and simultaneously, the polyethylene which can prepare the product with better wear resistance is obtainedAlkene powder.
The second technical scheme of the invention provides a preparation method of polyethylene powder, the polyethylene powder can be obtained by polymerization in a polyethylene reactor, and the reactor is added with single-site catalyst, cocatalyst, ethylene, hydrogen, comonomer and other raw materials under the protection of anhydrous and anaerobic and full nitrogen, and polymerization is carried out at high temperature.
Further, the reactor is a slurry tank reactor, a slurry loop reactor, a gas phase fluidized bed reactor or a combination of the above reactors.
Further, the molecular weight of the polyethylene powder can be controlled by the amount of hydrogen added, and the amount of hydrogen added is 0 to 100ppm depending on the characteristics of the catalyst, and it should be noted that when the amount of hydrogen added is 0, it means that hydrogen is not added at this time, and preferably the amount of hydrogen added is not 0. The number of the carbon number methyl groups can be controlled by the addition amount of the comonomer, and the addition amount is 0-20% of the ethylene amount according to different catalyst characteristics. Similarly, when the addition amount of the comonomer is 0, it means that the comonomer is not added at this time, and preferably, the addition amount thereof is not 0.
Further, the comonomer may be an a-olefin such as propylene, butene, hexene, octene, etc.
Further, the auxiliary catalyst is auxiliary agents such as triethylaluminum, triisobutylaluminum, methylaluminoxane and the like. The molar ratio of the cocatalyst to the single site catalyst is 0 to 300, and preferably the cocatalyst is added in an amount other than 0.
Further, as the polymerization temperature increases, the weight average molecular weight of the polyethylene decreases. As the amount of hydrogen added increases, the weight average molecular weight of the polyethylene decreases greatly.
The weight average molecular weight Mw and the number of the thousands of carbon methyl groups of the obtained polyethylene powder can be controlled by the addition amount of the hydrogen and the comonomer, the molecular weight distribution value Mw/Mn of the polyethylene powder can be controlled by the selection of the catalyst and the type of the cocatalyst, and when the obtained polyethylene powder reaches the molecular structure parameter of the polyethylene powder in the technical scheme of the invention, the wear-resisting property close to the ultra-high molecular weight polyethylene can be obtained.
As the amount of hydrogen added increases, the molecular weight of the polyethylene powder will gradually decrease, and low molecular weight will increase the processability of the powder, but will decrease the abrasion resistance of the product obtained by processing the polyethylene powder.
The third technical scheme of the invention provides application of polyethylene powder, and the polyethylene powder is subjected to powder processing by hot press molding, extrusion molding, blow molding or rotational molding to obtain the wear-resistant product.
Further, in the hot press molding process, polyethylene powder is firstly mixed with an antioxidant and then is processed, the processing temperature is 180-200 ℃, and the hot press time is 30-90 min.
Further, in the extrusion molding process, polyethylene powder is firstly mixed with an auxiliary agent comprising an antioxidant, a release agent and a lubricant and then subjected to melt processing, and the processing temperature of a melting section is 180-240 ℃.
Further, in the blow molding process, polyethylene powder is firstly mixed with auxiliary agents including an antioxidant, a release agent and a lubricant and then processed, and the processing temperature of a melting section is 180-260 ℃.
Further, in the rotational molding process, polyethylene powder is firstly mixed with an antioxidant and then is processed, the processing temperature is 180-260 ℃, and the hot pressing time is 30-90 min.
Furthermore, in the processing process of the polyethylene powder, the addition amount of various auxiliary agents such as an antioxidant, a release agent, a lubricant and the like is lower than 1% of the total mass of the polyethylene powder.
The release agent used in the processing process of the polyethylene powder is one or more of titanate, fluororubber, stearate or aluminate compounds; the antioxidant is one or more of 1010, 168, B215, 1076, 3114 and 1135.
The fourth technical scheme of the invention provides a method for improving the wear resistance of a polyethylene product, which is finished by carrying out powder processing on polyethylene powder through hot press molding, extrusion molding, blow molding or rotational molding, wherein the polyethylene powder is prepared by adopting a single-activity catalyst, the weight average molecular weight is 20 ten thousand-100 ten thousand, the molecular weight distribution Mw/Mn is less than or equal to 3.5, and the number of thousands of carbon short-chain branches SCB is 1-80; the melt index MI is 0.01-20g/10min at 190 ℃ under 21.6kg load.
The invention obtains the polyethylene powder raw material with proper molecular chain structure through polymerization, the powder raw material has obviously excellent wear-resisting property compared with the traditional polyethylene, and can be directly processed by means of extrusion, rotational molding, blow molding and the like to obtain polyethylene products with certain wear resistance, and can also be modified or improved by means of technology to obtain polyethylene products with more excellent wear resistance.
Drawings
FIG. 1 shows calculated degree of entanglement C of molecular chains tan Relationship with Mw, mw/Mn values.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.
In the examples below, the metallocene polyethylene catalyst was an actgcat catalyst from GRACE.
The transition metal polyethylene catalyst is obtained by laboratory synthesis, and the synthesis means are as follows:
synthesis of carrier Mg 1:
n (methanol) n (original support Mg (OH) 2 ) The reaction flask was added =10:1, the temperature was raised to 100 ℃, diisobutyl phthalate, n (diisobutyl phthalate): n (original carrier Mg (OH) 2 ) =1:1, stirring at high speed of 500 rpm, reacting for 4h, and rapidly pressing the obtained mixture into a large amount of n-hexane at-15 ℃ to shape to obtain solid.
Heating the obtained solid to 60deg.C under nitrogen protection, and maintaining for 5 hr to obtain the required carrier Mg1 with average particle diameter of 150 μm and specific surface area of 450m 2 And/g. Catalyst loading: transition metal titanium Complex (structure: 33.6mg, 50. Mu. Mol,673 g/mol) prepared according to CN 202010061212.6 was dissolved in 10mL of toluene, triethylaluminum (0.1 mL, 100. Mu. Mol,1.0 was addedmol/L), stirring for 30 minutes at room temperature to obtain a catalyst solution; adding a carrier Mg1 (1.0 g), stirring for 1 hour at room temperature, filtering, washing with toluene, and vacuum drying to obtain a supported catalyst C1;
transition metal titanium complex:
characterization data for the polyethylene feed in the examples were obtained by the following method:
test method
The abrasion resistance of the polyethylene product is tested by adopting the method and equipment of GB 3960-83.
The polyethylene powder was tested for molecular weight and molecular weight distribution using the method and apparatus of ASTM D6474.
The remainder, unless specifically stated, is indicative of conventional commercial materials or processing techniques in the art.
Example 1
The polyethylene polymerization was carried out in a 2L batch kettle reactor. Firstly, the polymerization reaction kettle is replaced by nitrogen for a plurality of times, the air in the reaction kettle is removed, and then ethylene is replaced for a plurality of times. After the gas replacement is completed, nitrogen is introduced, and the normal hexane, the transition metal catalyst and the cocatalyst triethylaluminum, and the methylaluminoxane are pressed into the replaced reaction kettle through the nitrogen. 1.5L of n-hexane, 0.2g of catalyst, 0.5g of triethylaluminum and 0.3g of methylaluminoxane. Introducing ethylene into the transition metal, maintaining the set pressure at 0.8MPa, opening the reaction kettle, stirring, gradually heating the reaction kettle through heat conducting oil, and keeping the reaction for 2h when the temperature of the reaction kettle is raised to 80 ℃. 1% of octene monomer (i.e., 1% of the molar amount of ethylene, the same applies below) was added at the beginning of the reaction. And closing the entry of ethylene gas after the reaction is finished, cooling the ethylene gas by cooling water, removing the upper-layer n-hexane, and taking out the product. The obtained polyethylene powder has weight average molecular weight of 30 ten thousand, mw/Mn of 2.0, thousand carbon short-chain branch number SCB of 1-10 and MI of 4.6g/10min, antioxidant 1010, zinc stearate and calcium stearate are added into a mixing kettle to blend for 3min according to the proportion of 99.3%, 0.2%, 0.3% and 0.2% (weight proportion), and then the mixture is fed into a single screw extruder for polyethylene pipe extrusion. The temperature of the feeding section and the extrusion temperature of the single screw are respectively 60 ℃ and 190 ℃ and the rotating speed is 60 revolutions/min. The extruded pipe melt is drawn by a water cooling box to prepare the polyethylene pipe, and the extrusion rate of the pipe can reach 1-2m/min.
Testing the wear resistance of the polyethylene pipe, C tan The value was 15 and the wear rate was 2.4%.
Example 2
The polyethylene polymerization was carried out in a 2L batch kettle reactor. Firstly, the polymerization reaction kettle is replaced by nitrogen for a plurality of times, the air in the reaction kettle is removed, and then ethylene is replaced for a plurality of times. After the gas replacement is completed, nitrogen is introduced, and the n-hexane, the post-metallocene catalyst and the cocatalyst triisobutylaluminum and methylaluminoxane are pressed into the replaced reaction kettle through the nitrogen. 1.5L of n-hexane, 0.2g of catalyst, 0.5g of triethylaluminum and 0.3g of methylaluminoxane. Ethylene is introduced, the set pressure is kept at 0.9MPa, the reaction kettle is opened for stirring, the temperature of the reaction kettle is gradually increased through heat conduction oil, and the reaction is kept for 2h after the temperature of the reaction kettle is increased to 75 ℃.4% of butene monomer was added at the beginning of the reaction. And closing the entry of ethylene gas after the reaction is finished, cooling the ethylene gas by cooling water, removing the upper-layer n-hexane, and taking out the product. The obtained polyethylene powder has a weight average molecular weight of 50 ten thousand, mw/Mn of 2.6, a thousand carbon short-chain branch number SCB of 10-30, and MI of 1.2g/10min, antioxidant 176, fluororubber and zinc stearate are added into a mixing kettle to blend for 3min according to the proportion of 99.57%, 0.2%, 0.03% and 0.2% (weight ratio), and then the mixture is fed into a blow molding device to be blow molded. The blow molding process melt stage temperature was 210 ℃. The extrusion melt is extruded through a die to form a hollow member.
Testing the wear resistance of the medium space sampling, C tan The value was 27 and the wear rate was 1.2%.
Example 3
The polyethylene polymerization was carried out in a 2L batch kettle reactor. Firstly, the polymerization reaction kettle is replaced by nitrogen for a plurality of times, the air in the reaction kettle is removed, and then ethylene is replaced for a plurality of times. After the gas replacement is completed, nitrogen is introduced, and the normal hexane, the metallocene catalyst and the cocatalyst triethylaluminum, and the methylaluminoxane are pressed into the replaced reaction kettle through the nitrogen. 1.5L of n-hexane, 0.2g of catalyst, 0.5g of triethylaluminum and 0.3g of methylaluminoxane. Ethylene is introduced, the set pressure is kept at 1MPa, the reaction kettle is opened for stirring, the temperature of the reaction kettle is gradually increased through heat conduction oil, and the reaction is kept for 2h after the temperature of the reaction kettle is increased to 85 ℃. 20% of propylene monomer was added at the beginning of the reaction. And closing the entry of ethylene gas after the reaction is finished, cooling the ethylene gas by cooling water, removing the upper-layer n-hexane, and taking out the product. The obtained polyethylene powder has a weight average molecular weight of 20 ten thousand, mw/Mn of 3.5, a thousand carbon short-chain branch number SCB of 60-80 and MI of 6.1g/10min, and antioxidant B215 are added into a mixing kettle in a proportion of 99.8wt% and 0.2wt% for 3min, and then fed into rotational molding equipment for rotational molding. The temperature of the rotational molding processing melting section is 260 ℃.
Testing the abrasion resistance of the rotational molding part by sampling, C tan The value was 10 and the wear rate was 2.7%.
Example 4
The polyethylene polymerization was carried out in a 2L batch kettle reactor. Firstly, the polymerization reaction kettle is replaced by nitrogen for a plurality of times, the air in the reaction kettle is removed, and then ethylene is replaced for a plurality of times. After the gas replacement is completed, nitrogen is introduced, and the normal hexane, the transition metal catalyst and the cocatalyst triethylaluminum, and the methylaluminoxane are pressed into the replaced reaction kettle through the nitrogen. 1.5L of n-hexane, 0.2g of catalyst, 0.5g of triethylaluminum and 0.3g of methylaluminoxane. Ethylene is introduced, the set pressure is kept at 0.8MPa, the reaction kettle is opened for stirring, the temperature of the reaction kettle is gradually increased through heat conduction oil, and the reaction is kept for 2h after the temperature of the reaction kettle is increased to 83 ℃. Octene monomer 8% was added at the beginning of the reaction. And closing the entry of ethylene gas after the reaction is finished, cooling the ethylene gas by cooling water, removing the upper-layer n-hexane, and taking out the product. The obtained polyethylene has the weight average molecular weight of 100 ten thousand, the Mw/Mn of 3.0, the thousand carbon short-chain branch number SCB of 20-30 and the MI of 0.01g/10min, and the antioxidant 1076 are added into a mixing kettle in the proportion of 99.5wt% and 5wt% for 5min, and then are put into a molding die for sheet compression molding. The molding temperature was 220℃and the molding time was 60 minutes.
Sampling the molded plate for testing the wear resistance, C tan The value was 37 and the wear rate was 0.7%.
Comparative example 1
Firstly, carrying out surface treatment on aluminum oxide powder: firstly, heating ethanol to 60 ℃ in a three-neck flask, and then sequentially adding water and vinyltrimethoxysilane under stirring, wherein the molar ratio of water to coupling agent (namely vinyltrimethoxysilane) is 3:1, after the coupling agent is added for 1min, adding the aluminum oxide powder, wherein the mass ratio of the coupling agent to the aluminum oxide powder is 1:100, stirring was continued at 60℃for 30min. Then ethanol is distilled off at 60 ℃ firstly, and then the aluminum oxide powder is dried at 120 ℃ for 1h, so as to obtain the aluminum oxide powder with surface treatment for standby. The preparation of the polyolefin resin is then: the components of the system are premixed at high speed for 5min in a high-speed mixer, taken out and extruded in an extruder for granulation, the inlet temperature of the extruder is 60 ℃, the extrusion temperature is 200 ℃, then the extruder is dried at 80 ℃ for 1h, and finally the powder is ground to obtain the finished product powder, and the raw material is prepared according to the ratio shown in table 1, wherein the melt flow rate of LLDPE is 7.15g/10min, the Mw/Mn is more than 4, and the Mw is about 15 ten thousand. Wherein the UHMWPE has a flow rate of 0g/10min, a Mw/Mn of greater than 4, and a Mw of about 250 ten thousand.
The polyethylene modified material obtained in comparative example 1 gave a product having an abrasion rate of 2.9%.
Comparative example 2
The rotational molding grade crosslinked polyethylene wear-resistant composite material comprises the following raw materials in parts by weight:
firstly, carrying out surface treatment on molybdenum disulfide: a certain amount of coupling agent (namely DCP+TAIC) is weighed according to an experimental scheme, and a small amount of ethanol water solution is added to prepare a 20% concentration solution. The inorganic filler (namely molybdenum disulfide) is weighed according to the proportion, placed in a high-speed mixer, heated to 60 ℃ while being stirred at high speed, and the coupling agent solution is added dropwise by a dropper. And after the dripping is finished, continuously mixing at a high speed for 20min. Taking out the treated filler after mixing, and drying for 1h at 120 ℃ in a forced air drying box to obtain the inorganic filler with the surface treated; then the preparation of the wear-resistant composite material: mixing the linear low-density polyethylene, the ultra-high molecular weight polyethylene, the cross-linking agent and the auxiliary cross-linking agent uniformly, absorbing for 80-120 min at 85 ℃, adding the inorganic filler, the antioxidant and the like subjected to surface treatment, uniformly mixing by a high-speed mixer, extruding and granulating by a double-screw extruder at 190 ℃, drying for 2h at 80-90 ℃, and grinding to obtain the finished powder.
The melt flow rate of the linear low density polyethylene is 7.24g/10min, mw/Mn is more than 4, and other fillers, cross-linking agents and antioxidants are all commercially available. The LLDPE abrasion rate was 10.48% and the abrasion rate after modification was 7.83%.
Comparative example 3
An ultra-high molecular weight polyethylene pipe, which comprises the following raw materials in parts by weight: 80 parts of ultra-high molecular weight polyethylene (250 ten thousand, mw/Mn is greater than 4), 5 parts of clay, 2 parts of carbon black, 0.1 part of stearic acid, 0.1 part of zinc borate, 0.1 part of antistatic agent and 0.1 part of antioxidant.
The preparation method comprises the following steps:
(1) Weighing 80 parts of ultra-high molecular weight polyethylene, 5 parts of clay, 2 parts of carbon black, 0.1 part of stearic acid, 0.1 part of zinc borate, 0.1 part of antistatic agent and 0.1 part of antioxidant, and uniformly mixing and stirring to obtain a mixture, wherein the mixing and stirring speed is 35r/min, and the stirring time is 20min;
(2) Extruding the mixture in an extruder, wherein the temperature of each section of the extruder is 90 ℃, the temperature of each section of the extruder is 180 ℃, the temperature of each section of the extruder is 190 ℃, the temperature of each section of the extruder is 200 ℃, and the rotating speed of a host machine is 45r/min; the extruder pressure is 35Mpa;
(3) Cooling, cooling with 70deg.C water, and shaping.
The abrasion rate of the pipe obtained in the comparative example is 0.9%, but the extrusion speed of the pipe is relatively slow, about 1-2cm/min, and the extrusion speed of the pipe can reach 1-2m/min in the examples.
Comparative example 4
The polyethylene polymerization was carried out in a 2L batch kettle reactor. Firstly, the polymerization reaction kettle is replaced by nitrogen for a plurality of times, the air in the reaction kettle is removed, and then ethylene is replaced for a plurality of times. After the gas replacement is completed, nitrogen is introduced, and the N-hexane, the Z-N catalyst and the cocatalyst triisobutylaluminum are pressed into the replaced reaction kettle through the nitrogen. 1.5L of normal hexane, 0.2g of catalyst and 0.8g of triethylaluminum. Ethylene is introduced, the set pressure is kept at 0.9MPa, the reaction kettle is opened for stirring, the temperature of the reaction kettle is gradually increased through heat conduction oil, and the reaction is kept for 2h after the temperature of the reaction kettle is increased to 80 ℃.4% of butene monomer was added at the beginning of the reaction. And closing the entry of ethylene gas after the reaction is finished, cooling the ethylene gas by cooling water, removing the upper-layer n-hexane, and taking out the product. The obtained polyethylene with weight average molecular weight of 350 ten thousand, mw/Mn of 5.5, thousand carbon short-chain branch number SCB of 20-30 and MI of 0g/10min, antioxidant 1076 are added into a mixing kettle in a proportion of 99.5 percent to 5 percent for blending for 5 minutes, and then the mixture is put into a molding die for sheet material compression molding. The molding temperature was 220℃and the molding time was 60 minutes.
The molded sheet was sampled for abrasion resistance, with an abrasion rate of 1.0%.
Comparative example 5
The polyethylene polymerization was carried out in a 2L batch kettle reactor. Firstly, the polymerization reaction kettle is replaced by nitrogen for a plurality of times, the air in the reaction kettle is removed, and then ethylene is replaced for a plurality of times. After the gas replacement is completed, nitrogen is introduced, and the N-hexane, the Z-N catalyst and the cocatalyst triethylaluminum are pressed into the replaced reaction kettle through the nitrogen. 1.5L of normal hexane, 0.2g of catalyst and 0.8g of triethylaluminum. Ethylene is introduced, the set pressure is kept at 0.8MPa, the reaction kettle is opened for stirring, the temperature of the reaction kettle is gradually increased through heat conduction oil, and the reaction is kept for 2h after the temperature of the reaction kettle is increased to 80 ℃. 1% of octene monomer was added at the beginning of the reaction. And closing the entry of ethylene gas after the reaction is finished, cooling the ethylene gas by cooling water, removing the upper-layer n-hexane, and taking out the product. The obtained polyethylene powder has weight average molecular weight of 30 ten thousand, mw/Mn of 6.0, thousand carbon short-chain branch number SCB of 1-10, MI of 8.9g/10min, antioxidant 1010, zinc stearate and calcium stearate are added into a mixing kettle to blend for 3min according to the proportion of 99.3%, 0.2%, 0.3% and 0.2% (weight proportion), and then the mixture is fed into a single screw extruder for polyethylene pipe extrusion. The temperature of the single screw from the feeding section and the extrusion temperature are respectively 60 ℃,190 ℃ and the rotating speed is 60 revolutions per minute. The extruded pipe melt is drawn by a water cooling box to prepare the polyethylene pipe, and the extrusion rate of the pipe can reach 1-2m/min.
Testing the wear resistance of the polyethylene pipe, C tan The value was 6 and the wear rate was 7.4%.
As shown in the table, the polyethylene powder with proper molecular structure can be directly processed to obtain polyethylene products with abrasion rate lower than 3.0%, while the abrasion rate of the commercial polyethylene with the same molecular weight section is about 10.0%, and the abrasion resistance of the polyethylene powder is far better than that of the commercial polyethylene. Meanwhile, compared with an ultrahigh molecular weight polyethylene extruded product, the invention has low processing cost and high processing efficiency. Compared with the ultra-high molecular weight polyethylene plate, the wear resistance of the plate product with the molecular weight of 100 ten thousand can be even slightly better than that of the plate product prepared by the traditional ultra-high molecular weight polyethylene with the molecular weight of 350 ten thousand. Therefore, the polyethylene with the specific structure prepared by the invention has more excellent wear resistance than the similar products at present.
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.
Claims (10)
1. The polyethylene powder is characterized in that the polyethylene powder is prepared by a single-activity catalyst, the weight average molecular weight is 20-100 ten thousand, the molecular weight distribution Mw/Mn is less than or equal to 3.5, and the thousands of carbon short-chain branch number SCB is 1-80; the melt index MI is 0.01-20g/10min at 190 ℃ under 21.6kg load.
2. A polyethylene powder according to claim 1, wherein the single-site catalyst is a metallocene catalyst or a transition metal catalyst.
3. The method for preparing polyethylene powder according to claim 1 or 2, wherein a single-site catalyst, a cocatalyst, ethylene, hydrogen and a comonomer are added into a reactor which is anhydrous, anaerobic and full of inert gas protection, and polymerization is carried out at high temperature to obtain the objective polyethylene powder.
4. A process for the preparation of a polyethylene powder according to claim 3, wherein the hydrogen is added in an amount of 0 to 100ppm;
the addition amount of the comonomer is 0-20% of the molar amount of ethylene;
the molar ratio of the cocatalyst to the single-site catalyst is 0-300;
the comonomer is propylene, butene, hexene or octene;
the cocatalyst is triethylaluminum, triisobutylaluminum or methylaluminoxane.
5. Use of a polyethylene powder according to claim 1, wherein the polyethylene powder is powder processed by hot press molding, extrusion molding, blow molding or rotomolding to obtain a wear resistant article.
6. The method according to claim 5, wherein the polyethylene powder is processed after being blended with the antioxidant in the hot press molding process, the processing temperature is 180-200 ℃, and the hot press time is 30-90 min.
7. The method according to claim 5, wherein the polyethylene powder is melt-processed after being blended with additives including antioxidants, mold release agents and lubricants during extrusion, and the processing temperature in the melt section is 180-240 ℃.
8. The method according to claim 5, wherein the polyethylene powder is processed after blending with additives including antioxidants, mold release agents and lubricants during blow molding, and the melting stage is processed at 180-260 ℃.
9. The method according to claim 5, wherein the polyethylene powder is processed after being blended with the antioxidant in the rotational molding process, the processing temperature is 180-260 ℃, and the hot pressing time is 30-90 min.
10. A method for improving the wear resistance of a polyethylene product is characterized in that the method is completed by carrying out powder processing on polyethylene powder through hot press molding, extrusion molding, blow molding or rotational molding, wherein the polyethylene powder is prepared by adopting a single-activity catalyst, the weight average molecular weight is 20 ten thousand-100 ten-thousand, the molecular weight distribution Mw/Mn is less than or equal to 3.5, and the number of thousands of carbon short-chain branches SCB is 1-80; the melt index MI is 0.01-20g/10min at 190 ℃ under 21.6kg load.
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