CN115403688A - Polyethylene powder and molded body - Google Patents
Polyethylene powder and molded body Download PDFInfo
- Publication number
- CN115403688A CN115403688A CN202210549232.7A CN202210549232A CN115403688A CN 115403688 A CN115403688 A CN 115403688A CN 202210549232 A CN202210549232 A CN 202210549232A CN 115403688 A CN115403688 A CN 115403688A
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- CN
- China
- Prior art keywords
- polyethylene powder
- less
- polyethylene
- polymerization
- catalyst
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000004698 Polyethylene Substances 0.000 title claims abstract description 255
- -1 Polyethylene Polymers 0.000 title claims abstract description 245
- 229920000573 polyethylene Polymers 0.000 title claims abstract description 241
- 239000000843 powder Substances 0.000 title claims abstract description 237
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 23
- 238000005259 measurement Methods 0.000 claims abstract description 22
- 230000003647 oxidation Effects 0.000 claims abstract description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000001301 oxygen Substances 0.000 claims abstract description 19
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 19
- 230000006698 induction Effects 0.000 claims abstract description 16
- 239000002245 particle Substances 0.000 claims description 43
- 239000004711 α-olefin Substances 0.000 claims description 14
- 230000004584 weight gain Effects 0.000 claims 1
- 235000019786 weight gain Nutrition 0.000 claims 1
- 238000006116 polymerization reaction Methods 0.000 description 107
- 239000003054 catalyst Substances 0.000 description 71
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 54
- 239000002904 solvent Substances 0.000 description 50
- 238000000034 method Methods 0.000 description 49
- 239000011949 solid catalyst Substances 0.000 description 38
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 33
- 239000005977 Ethylene Substances 0.000 description 33
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 32
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 28
- 238000006243 chemical reaction Methods 0.000 description 28
- 239000007789 gas Substances 0.000 description 24
- 239000002002 slurry Substances 0.000 description 23
- 239000000243 solution Substances 0.000 description 21
- 230000000694 effects Effects 0.000 description 19
- 239000011777 magnesium Substances 0.000 description 19
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 description 18
- 230000006866 deterioration Effects 0.000 description 18
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 description 18
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- 238000004519 manufacturing process Methods 0.000 description 16
- 229910052751 metal Inorganic materials 0.000 description 15
- 239000002184 metal Substances 0.000 description 15
- 238000000465 moulding Methods 0.000 description 14
- 239000001257 hydrogen Substances 0.000 description 13
- 229910052739 hydrogen Inorganic materials 0.000 description 13
- 239000011575 calcium Substances 0.000 description 12
- 238000003756 stirring Methods 0.000 description 12
- 239000002994 raw material Substances 0.000 description 11
- 239000000654 additive Substances 0.000 description 10
- 238000001035 drying Methods 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 9
- 229910052749 magnesium Inorganic materials 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 8
- 230000002159 abnormal effect Effects 0.000 description 8
- 239000003426 co-catalyst Substances 0.000 description 8
- NNBZCPXTIHJBJL-UHFFFAOYSA-N decalin Chemical compound C1CCCC2CCCCC21 NNBZCPXTIHJBJL-UHFFFAOYSA-N 0.000 description 8
- 238000000926 separation method Methods 0.000 description 8
- 239000010936 titanium Substances 0.000 description 8
- MCULRUJILOGHCJ-UHFFFAOYSA-N triisobutylaluminium Chemical compound CC(C)C[Al](CC(C)C)CC(C)C MCULRUJILOGHCJ-UHFFFAOYSA-N 0.000 description 8
- 230000000996 additive effect Effects 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 6
- 238000000748 compression moulding Methods 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- 229910001873 dinitrogen Inorganic materials 0.000 description 6
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- 239000013585 weight reducing agent Substances 0.000 description 6
- 125000004432 carbon atom Chemical group C* 0.000 description 5
- 230000003749 cleanliness Effects 0.000 description 5
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- 238000003860 storage Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 239000011954 Ziegler–Natta catalyst Substances 0.000 description 4
- 238000007664 blowing Methods 0.000 description 4
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 description 4
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
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- 229910052791 calcium Inorganic materials 0.000 description 3
- 239000008116 calcium stearate Substances 0.000 description 3
- 235000013539 calcium stearate Nutrition 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
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- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 3
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- XWJBRBSPAODJER-UHFFFAOYSA-N 1,7-octadiene Chemical compound C=CCCCCC=C XWJBRBSPAODJER-UHFFFAOYSA-N 0.000 description 2
- VQOXUMQBYILCKR-UHFFFAOYSA-N 1-Tridecene Chemical compound CCCCCCCCCCCC=C VQOXUMQBYILCKR-UHFFFAOYSA-N 0.000 description 2
- AFFLGGQVNFXPEV-UHFFFAOYSA-N 1-decene Chemical compound CCCCCCCCC=C AFFLGGQVNFXPEV-UHFFFAOYSA-N 0.000 description 2
- CRSBERNSMYQZNG-UHFFFAOYSA-N 1-dodecene Chemical compound CCCCCCCCCCC=C CRSBERNSMYQZNG-UHFFFAOYSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- JRZJOMJEPLMPRA-UHFFFAOYSA-N 1-nonene Chemical compound CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 2
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 description 2
- HFDVRLIODXPAHB-UHFFFAOYSA-N 1-tetradecene Chemical compound CCCCCCCCCCCCC=C HFDVRLIODXPAHB-UHFFFAOYSA-N 0.000 description 2
- DCTOHCCUXLBQMS-UHFFFAOYSA-N 1-undecene Chemical compound CCCCCCCCCC=C DCTOHCCUXLBQMS-UHFFFAOYSA-N 0.000 description 2
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- RGSFGYAAUTVSQA-UHFFFAOYSA-N Cyclopentane Chemical compound C1CCCC1 RGSFGYAAUTVSQA-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 238000005481 NMR spectroscopy Methods 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
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- 239000012986 chain transfer agent Substances 0.000 description 2
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 description 2
- 230000001186 cumulative effect Effects 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000002845 discoloration Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- SNRUBQQJIBEYMU-UHFFFAOYSA-N dodecane Chemical compound CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 description 2
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- 229920001038 ethylene copolymer Polymers 0.000 description 2
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- 239000010408 film Substances 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
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- GWTMSNCNGOSQAD-UHFFFAOYSA-J hexane;tetrachlorotitanium Chemical compound [Cl-].[Cl-].[Cl-].[Cl-].[Ti+4].CCCCCC GWTMSNCNGOSQAD-UHFFFAOYSA-J 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 description 2
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- 238000000691 measurement method Methods 0.000 description 2
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- GDOPTJXRTPNYNR-UHFFFAOYSA-N methylcyclopentane Chemical compound CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 description 2
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- YVHUUEPYEDOELM-UHFFFAOYSA-N 2-ethylpropanedioic acid;piperidin-1-id-2-ylmethylazanide;platinum(2+) Chemical compound [Pt+2].[NH-]CC1CCCC[N-]1.CCC(C(O)=O)C(O)=O YVHUUEPYEDOELM-UHFFFAOYSA-N 0.000 description 1
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- 238000005245 sintering Methods 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 1
- ZRDRRLQUBZPUOP-UHFFFAOYSA-N trichloro(hydroxy)silane Chemical compound O[Si](Cl)(Cl)Cl ZRDRRLQUBZPUOP-UHFFFAOYSA-N 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
- 238000004383 yellowing Methods 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
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F110/00—Homopolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F110/02—Ethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
-
- 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
- C08L23/06—Polyethene
-
- 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
- C08F2500/00—Characteristics or properties of obtained polyolefins; Use thereof
- C08F2500/01—High molecular weight, e.g. >800,000 Da.
-
- 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
- C08F2500/00—Characteristics or properties of obtained polyolefins; Use thereof
- C08F2500/17—Viscosity
-
- 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
- C08F2500/00—Characteristics or properties of obtained polyolefins; Use thereof
- C08F2500/18—Bulk density
-
- 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
- C08F2500/00—Characteristics or properties of obtained polyolefins; Use thereof
- C08F2500/24—Polymer with special particle form or size
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/04—Homopolymers or copolymers of ethene
- C08J2323/06—Polyethene
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- Chemical & Material Sciences (AREA)
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- Chemical Kinetics & Catalysis (AREA)
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- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The present invention relates to a polyethylene powder and a molded article. The invention provides a polyethylene powder which has excellent molecular weight stability and can obtain a molded body with excellent whiteness and cleanness, and a molded body thereof. Polyethylene powder having an intrinsic viscosity of 3.0dl/g or more and less than 30.0dl/g and a heat flow of 0.03mW or more and less than 0.25mW after 60 minutes after switching to oxygen in an oxidation induction time measurement (150 ℃, under oxygen, sample mass 5 mg) according to ISO11357-6 (2018).
Description
Technical Field
The present invention relates to a polyethylene powder and a molded article.
Background
Polyethylene is easily melt-processed, and a molded article obtained using polyethylene is excellent in mechanical strength, chemical resistance, rigidity, and the like, and therefore has been used for various applications such as films, sheets, microporous films, fibers, foams, and sintered bodies.
In particular, ultrahigh molecular weight polyethylene has high practicability because it has high mechanical strength and excellent sliding properties and abrasion resistance.
However, the ultra-high-molecular-weight polyethylene has low fluidity even when melted at a temperature not lower than the melting point, and therefore it is difficult to use the ultra-high-molecular-weight polyethylene as pellets or powder. As a method for molding the ultrahigh molecular weight polyethylene powder, a compression molding method is known in which an ultrahigh molecular weight polyethylene powder is press-molded under heating and then cut into a shape to be used; a method of forming a sheet-like or filament-like product by dissolving it in a solvent such as liquid paraffin, stretching it, and removing the solvent (see, for example, patent documents 1 and 2).
On the other hand, in recent years, there has been an increasing demand for cleanability of chemical solutions, cleaning water, and the like used in manufacturing processes of displays, electronic components, various media devices, and the like.
For example, when ultra-high molecular weight polyethylene containing additives, impurities, and oligomers produced by degradation is used as a container for storing high-purity chemicals, ultrapure water, and the like (hereinafter, referred to as a contact object) or a filter for filtration, there is a problem that these substances may elute to contaminate or deteriorate the contact object.
In view of the above problems, as for a high-purity polyethylene resin material, for example, the following techniques are disclosed: a resin composition of ultra-high-molecular-weight polyethylene having an intrinsic viscosity of 10dl/g or more and 80dl/g or less and polyethylene having a molecular weight distribution (Mw/Mn) of 4 or less is a polyethylene resin material having a small content of low-molecular-weight components and excellent in cleanability (see, for example, patent document 3).
In addition, for example, the following techniques are disclosed: ultra-high molecular weight polyethylene having an intrinsic viscosity of 10dl/g or more and 60dl/g or less is excellent in cleaning property because it has a low chlorine content, inhibits corrosion of a molding machine, and does not require addition of a metal soap or the like as a neutralizer (for example, see patent document 4).
Documents of the prior art
Patent document
[ patent document 1] Japanese patent No. 6195403
[ patent document 2] Japanese patent application laid-open No. 2020-16007
[ patent document 3] Japanese patent application laid-open No. 2017-165938
[ patent document 4] Japanese patent application laid-open No. 2018-145412
Disclosure of Invention
Problems to be solved by the invention
In order to express excellent physical properties in a compression molded product of ultra-high molecular weight polyethylene powder, it is necessary to completely fuse the powder to each other and to perform compression processing at high temperature for a long time. Further, in recent years, the use of the above compression molded articles has increased in which higher strength and excellent dimensional accuracy are required, and there has been an increasing need to perform compression molding for a longer time and at a higher temperature than in the past and to perform annealing at a temperature not higher than the melting point for a long time in order to relax residual strain after molding. In addition, even when the ultra-high-molecular-weight polyethylene powder is used for a separator or a high-strength fiber, the undissolved powder is strictly managed, and therefore, in order to completely dissolve the ultra-high-molecular-weight polyethylene powder in a solvent, kneading is performed for a longer time and at a higher temperature than in the conventional case. In the above-mentioned various applications, ultrahigh molecular weight polyethylene excellent in detergency and whiteness is required.
However, the techniques disclosed in patent documents 1 and 2 have the following problems: in order to suppress deterioration of the ultra-high-molecular-weight polyethylene powder, a large amount of a neutralizing agent such as an antioxidant or calcium stearate is added, and then heating is performed to produce a molded article and high-strength fibers, and the molded article is poor in cleanability because the additive is eluted during use.
Patent document 3 describes that discoloration (yellowing), oxidative degradation, and the like due to titanium are suppressed, and that the composition is clean with a small amount of low-molecular-weight components, but does not describe degradation due to other metal components or the polymer structure of the ultra-high-molecular-weight polyethylene powder, and has a problem that a molecular weight is reduced or gelation occurs in a compression molding step of heating for a long time.
Patent document 4 describes that the chlorine content in the ultra-high-molecular-weight polyethylene powder is reduced, but there is a problem that the content of impurities such as catalyst residues is large, and there is no description about deterioration suppression, and there is a limitation on applications and uses requiring extremely strict cleanliness.
In view of the problems of the prior art, it is an object of the present invention to provide a polyethylene powder which has excellent stability of molecular weight and can give a molded article having excellent whiteness and cleanability, and a molded article thereof.
Means for solving the problems
The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that a polyethylene powder having a predetermined intrinsic viscosity and a predetermined heat flow in an oxidation induction time measurement can solve the above problems, and have completed the present invention.
Namely, the present invention is as follows.
[1]
A polyethylene powder having an intrinsic viscosity of 3.0dl/g or more and less than 30.0dl/g and
the heat flow of the polyethylene powder 60 minutes after switching to oxygen was 0.03mW or more and less than 0.25mW in the measurement of the oxidation induction time according to ISO11357-6 (2018) (150 ℃, under oxygen, sample mass 5 mg).
[2]
The polyethylene powder according to the above [1], wherein the content of Mg in the polyethylene powder is less than 10.0ppm.
[3]
The polyethylene powder according to the above [1] or [2], wherein the content of Ti in the polyethylene powder is less than 3.0ppm.
[4]
The polyethylene powder according to any one of the above [1] to [3], wherein the content of Al in the polyethylene powder is less than 8.0ppm.
[5]
The polyethylene powder according to any one of the above [1] to [4], wherein the content of the α -olefin in the polyethylene powder is less than 0.10 mol%.
[6]
The polyethylene powder according to any one of the above [1] to [5], wherein a maximum increase in weight of the polyethylene powder when heated at 200 ℃ for 1 hour in air is less than 2.0%.
[7]
The polyethylene powder according to any one of the above [1] to [6], wherein the total mass ratio of particles having a particle diameter of 106 μm or more and less than 212 μm in the polyethylene powder is 50% by mass or more and less than 75% by mass or less.
[8]
As described above [1]～[7]The polyethylene powder as claimed in any one of the preceding claims, wherein the polyethylene powder has a close bulk density of 0.50g/cm or more 3 And less than 0.65g/cm 3 And are each and every
A value (close bulk density/loose bulk density) obtained by dividing the close bulk density of the polyethylene powder by a loose bulk density is 1.05 or more and less than 1.30.
[9]
The polyethylene powder according to any one of the above [1] to [8], wherein a content of Ca in the polyethylene powder is less than 10ppm.
[10]
A molded article comprising the polyethylene powder according to any one of the above [1] to [9 ].
Effects of the invention
The present invention provides a polyethylene powder which has excellent stability of molecular weight and can give a molded article having excellent whiteness and cleanability, and a molded article thereof.
Detailed Description
Hereinafter, a mode for carrying out the present invention (hereinafter, also referred to as "the present embodiment") will be described in detail.
The following embodiments are examples for illustrating the present invention, and the present invention is not intended to be limited to the following. The present invention can be implemented by various modifications within the scope of the gist thereof.
[ polyethylene powder ]
The polyethylene powder of the present embodiment has an intrinsic viscosity of 3.0dl/g or more and 30.0dl/g or less, and a heat flow of 0.03mW or more and 0.25mW or less 60 minutes after switching to oxygen in the oxidation induction time measurement (5 mg of sample mass under oxygen at 150 ℃).
With the above configuration, the polyethylene powder of the present embodiment has excellent stability of molecular weight and can provide a molded article having excellent whiteness and cleanability.
The polyethylene powder of the present embodiment is a so-called ultra-high molecular weight polyethylene powder having an intrinsic viscosity of 3.0dl/g or more.
Examples of the polyethylene constituting the polyethylene powder of the present embodiment include, but are not limited to, ethylene homopolymers and copolymers of ethylene and other comonomers.
The other comonomer is not particularly limited, and examples thereof include α -olefins and vinyl compounds.
Examples of the α -olefin include, but are not limited to, α -olefins having 3 to 20 carbon atoms. Specifically, there may be mentioned: propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, etc.
Examples of the vinyl compound include but are not limited to vinylcyclohexane, styrene, and derivatives thereof.
Further, as another comonomer, a nonconjugated polyene such as 1, 5-hexadiene or 1, 7-octadiene may be used as necessary.
In the case where the polyethylene powder of the present embodiment is a copolymer, the copolymer may be a ternary random polymer.
One kind of other comonomer may be used alone, or two or more kinds may be used in combination.
The amount of the other comonomer is preferably 0.1 mol% or less, more preferably 0.08 mol% or less, and still more preferably 0.06 mol% or less, based on 100 mol% of the ethylene copolymer. By adjusting the amount of the other comonomer to 0.1 mol% or less, the formation of tertiary carbon which is likely to deteriorate can be reduced, and the formation of oligomers tends to be suppressed. In addition, the catalyst activity in the polymerization reaction tends to increase, and the amount of metal components of the catalyst residue tends to be easily suppressed.
The amount of the comonomer in the polyethylene can be confirmed by an infrared analysis method, an NMR method, or the like.
(intrinsic viscosity [. Eta. ])
The intrinsic viscosity [. Eta. ] of the polyethylene powder of the present embodiment is not less than 3.0dl/g and less than 30.0dl/g, preferably not less than 3.5dl/g and less than 28.0dl/g, and more preferably not less than 4.0dl/g and less than 26.0dl/g.
It should be noted that the intrinsic viscosity can be measured in decalin at 135 ℃.
When the intrinsic viscosity [ η ] is 3.0dl/g or more, the amount of low-molecular-weight components having poor oxidation/degradation resistance is small, and the molecular chains are inhibited from being broken or crosslinked due to degradation during molding, thereby tending to deteriorate the durability during molding into a molded article. In addition, the molded article obtained from the polyethylene powder of the present embodiment tends to have sufficient mechanical strength and abrasion resistance.
On the other hand, by the intrinsic viscosity [. Eta. ] being less than 30.0dl/g, the catalyst activity in the polymerization reaction tends to be increased, and the amount of the metal component of the catalyst residue tends to be easily suppressed. Further, since the molding processability is excellent, the fusion force between the polyethylene powders is increased, the mechanical strength is excellent, and the solubility of the polyethylene powder also tends to be high.
The intrinsic viscosity [ η ] of the polyethylene powder can be controlled within the above numerical range by appropriately adjusting the polymerization conditions described later and the like. Specifically, the intrinsic viscosity [ η ] can be controlled by allowing hydrogen as a chain transfer agent to be present in the polymerization system, changing the polymerization temperature, or the like.
The intrinsic viscosity [ η ] of the polyethylene powder of the present embodiment can be obtained as follows: solutions were prepared by dissolving polyethylene powder in decalin at different concentrations, measuring the solution viscosity at 135 ℃ of the solution, and extrapolating the reduced viscosity calculated from the measured solution viscosity to a concentration of 0. Specifically, it can be obtained by the method described in the examples described below.
(Heat flow 60 minutes after switching to oxygen in the Oxidation Induction time measurement)
The polyethylene powder of the present embodiment has a heat flow of 0.03mW or more and less than 0.25mW, preferably 0.04mW or more and less than 0.24mW, and more preferably 0.05mW or more and less than 0.23mW, 60 minutes after switching to oxygen gas, as measured according to the oxidation induction time of ISO11357-6 (2018) (150 ℃, under oxygen, 5mg of sample mass).
The heat flow 60 minutes after switching to oxygen in the measurement of the oxidation induction time tends to be 0.03mW or more, and a molded article having a high purity tends to be obtained.
On the other hand, the heat flow 60 minutes after switching to oxygen in the measurement of the oxidation induction time is less than 0.25mW, so that the polyethylene powder is less likely to be oxidized and deteriorated, the breakage or crosslinking of the molecular chain due to deterioration in molding processing is suppressed, a molded article having excellent deterioration durability is obtained when the molded article is produced, and a molded article having high whiteness tends to be obtained.
The heat flow in the measurement of the oxidation induction time is measured in accordance with ISO11357-6 (2018), and the heat release due to the oxidation reaction of polyethylene can be measured using a Differential Scanning Calorimeter (DSC) or the like. As a measurement method, the temperature of the test sample was raised in a nitrogen atmosphere, and then when 150 ℃ was reached, the atmosphere was switched to an oxygen atmosphere, and the heat flow after 60 minutes at a constant temperature of 150 ℃ was measured. The heat flow 60 minutes after the switching to oxygen gas in the measurement of the oxidation induction time at 150 ℃ is described in detail in the examples described later.
As a method of controlling the heat flow 60 minutes after switching to oxygen in the oxidation induction time measurement to be in the range of 0.03mW or more and less than 0.25mW, a method of producing polyethylene having a structure with few impurities that promote deterioration as a polyethylene structure that is less likely to deteriorate without adding an additive such as an antioxidant can be cited. Specifically, there may be mentioned: reducing the formation of tertiary carbon which is liable to deteriorate to a predetermined amount or less; reducing double bonds at the ends of polymer chains, which are generated by abnormal reactions and thermal deterioration during polymerization, to a predetermined amount or less; reducing metal components such as catalyst residues promoting oxidative deterioration and oligomer components generated by abnormal reaction to below a predetermined amount; and the like.
More specific examples of the method include the following methods: carrying out uniform continuous polymerization in a system in which ethylene gas, a solvent, a catalyst and the like are continuously supplied into a polymerization system, and unreacted ethylene gas and solvent are continuously discharged together with the produced polyethylene powder; alternately introducing a main catalyst and a cocatalyst from the same line to inhibit local rapid polymerization; a polymerization reaction adjusted to a high activity to thereby suppress the amount of metal components of the catalyst residue; a condenser for cooling the vaporized solvent and the like during the polymerization reaction by using a jacket so as not to charge the polyethylene powder, which is accompanied by the vaporized solvent and in which an abnormal reaction has occurred, into the polymerization reactor again; introducing ethanol into a buffer tank before separating the polyethylene powder from the solvent so that the ethanol is 10 mass% of the solvent amount, thereby removing metal components and oligomer components as much as possible; spraying steam of water and isopropyl alcohol (70 mass%/30 mass%) to the polyethylene powder after polymerization, and removing the volatilized solvent and hydrochloric acid gas generated from the catalyst while blowing nitrogen gas at a temperature of 100 ℃ to 110 ℃; and so on.
In general, in the production process of the polyethylene powder, the polyethylene powder is easily oxidized and deteriorated due to local abnormal reaction during polymerization reaction, insufficient purification, deterioration during drying, and the like, but the polyethylene powder of the present embodiment is mainly characterized by having a structure that is not easily oxidized and deteriorated.
(Mg content)
The Mg content in the polyethylene powder of this embodiment is preferably less than 10.0ppm, more preferably less than 8.0ppm, even more preferably less than 6.0ppm.
When the Mg content is less than 10.0ppm, oxidative deterioration of polyethylene can be effectively suppressed, and a decrease in molecular weight and gelation caused by crosslinking reaction can be more effectively suppressed. In addition, when a molded article is produced, the molded article has excellent deterioration durability, and the coloring and embrittlement of the molded article tend to be suppressed.
The Mg content can be controlled within the above numerical range by increasing the productivity of polyethylene per unit catalyst.
The productivity of polyethylene per unit catalyst can be controlled by adjusting the polymerization temperature, polymerization pressure, slurry concentration of the reactor when manufacturing polyethylene. That is, in order to increase the productivity of polyethylene per unit catalyst of polyethylene constituting the polyethylene powder of the present embodiment, it is possible to increase the polymerization temperature, increase the polymerization pressure, and/or increase the slurry concentration.
The catalyst to be used is not particularly limited, and a general ziegler-natta catalyst, a metallocene catalyst, or the like can be mentioned as a preferable catalyst.
As a method for improving the productivity of polyethylene per unit catalyst, the following methods can be cited: alternately introducing a main catalyst and a cocatalyst from the same line to inhibit local rapid polymerization; a condenser for cooling the vaporized solvent and the like in the cooling of the polymerization reaction by using a jacket so as not to charge the polyethylene powder, which has undergone an abnormal reaction with the vaporized solvent, into the polymerization reactor again; introducing ethanol into a buffer tank before separating the polyethylene powder from the solvent so that the ethanol is 10 mass% of the solvent amount, thereby removing metal components and oligomer components as much as possible; separating the polyethylene powder from the solvent by a centrifugal separation method, wherein the amount of the solvent contained in the polyethylene powder before drying is adjusted to 70 mass% or less relative to the mass of the polyethylene powder; and so on. The Mg content in the polyethylene powder can be measured by the method described in examples described later.
(Ti content)
The Ti content in the polyethylene powder of the present embodiment is preferably less than 3.0ppm, more preferably less than 2.5ppm, and further preferably less than 2.0ppm.
When the Ti content is less than 3.0ppm, oxidative deterioration of polyethylene can be effectively suppressed, and a decrease in molecular weight and gelation caused by a crosslinking reaction can be more effectively suppressed. In addition, when a molded article is produced, the molded article has excellent deterioration durability, and the coloring and embrittlement of the molded article tend to be suppressed.
As a method for adjusting the Ti content to less than 3.0ppm, the same method as the above-mentioned method for controlling the Mg content can be applied.
(Al content)
The Al content in the polyethylene powder of the present embodiment is preferably less than 8.0ppm, more preferably less than 7.0ppm, and further preferably less than 6.0ppm.
When the Al content is less than 8.0ppm, oxidative deterioration of polyethylene can be effectively suppressed, and a decrease in molecular weight and gelation caused by a crosslinking reaction can be more effectively suppressed. In addition, when a molded article is produced, the molded article has excellent deterioration durability, and the coloring and embrittlement of the molded article tend to be suppressed.
As a method for adjusting the Al content to less than 8.0ppm, the same method as the above-mentioned method for controlling the Mg content can be applied.
(content of alpha-olefin)
The content of the α -olefin in the polyethylene powder of the present embodiment is preferably less than 0.10 mol%, more preferably 0.08 mol% or less, and still more preferably 0.06 mol% or less, assuming that the ethylene copolymer is 100 mol%.
By adjusting the content of the α -olefin to less than 0.10 mol%, the formation of a tertiary carbon which is likely to deteriorate can be reduced, and the formation of oligomers tends to be suppressed. In addition, the catalyst activity in the polymerization reaction tends to increase, and the amount of metal components of the catalyst residue tends to be easily suppressed.
The content of α -olefin in the polyethylene powder can be measured by infrared analysis or NMR.
The content of the α -olefin in the polyethylene powder of the present embodiment can be controlled within the above numerical range by adjusting the amount of the α -olefin added to the polymerization reactor relative to the amount of ethylene added.
(maximum rate of increase in Oxidation weight)
The maximum increase in the oxidized weight of the polyethylene powder of the present embodiment when heated at 200 ℃ under air is preferably less than 2.0%, more preferably less than 1.9%, and still more preferably less than 1.8%.
When the maximum increase rate of the oxidized weight of the polyethylene powder is less than 2.0% at 200 ℃ under air heating, the initial oxidation of polyethylene tends to be suppressed, and the subsequent chain reaction decomposition tends to be less likely to occur. Further, the storage stability of the polyethylene powder tends to be improved.
When polyethylene is heated under air, an increase in weight due to oxidation as an initial reaction of deterioration occurs. As the weight increase rate is smaller, the subsequent decrease in molecular weight due to the cleavage of the molecular chain and gelation due to the crosslinking reaction tend to be suppressed. In addition, in the case of storing the polyethylene powder for a long period of time in summer, although the polyethylene powder is slightly deteriorated during storage, the polyethylene powder in which the initial oxidation reaction does not easily occur tends to have improved storage stability, and therefore, the smaller the maximum increase rate of the oxidized weight is, the more preferable.
As a method for controlling the maximum increase rate of the oxidized weight of the polyethylene powder in the range of less than 2.0% when heated at 200 ℃ under air, the following methods can be mentioned: carrying out a uniform continuous polymerization in a system in which ethylene gas, a solvent, a catalyst and the like are continuously supplied into a polymerization system, and unreacted ethylene gas and solvent are continuously discharged together with a produced polyethylene powder; alternately introducing a main catalyst and a cocatalyst from the same line to inhibit local rapid polymerization; a polymerization reaction which is adjusted to be highly active, thereby suppressing the amount of metal components of the catalyst residue; a condenser for cooling the vaporized solvent and the like during the polymerization reaction by using a jacket so as not to charge the polyethylene powder, which is accompanied by the vaporized solvent and in which an abnormal reaction has occurred, into the polymerization reactor again; introducing ethanol into a buffer tank before separating the polyethylene powder from the solvent so that the ethanol is 10 mass% of the solvent amount, thereby removing metal components and oligomer components as much as possible; spraying steam of water and isopropyl alcohol (70 mass%/30 mass%) to the polyethylene powder after polymerization, and blowing nitrogen gas at a temperature of 100 ℃ to 110 ℃ to completely remove the volatilized solvent and hydrochloric acid gas generated from the catalyst; and so on.
(Total mass ratio of particles having particle diameter of 106 μm or more and less than 212 μm)
The total mass ratio of the particles having a particle diameter of 106 μm or more and less than 212 μm in the polyethylene powder of the present embodiment is preferably 50% by mass or more and less than 75% by mass, more preferably 52% by mass or more and less than 73% by mass, and still more preferably 54% by mass or more and less than 71% by mass.
When the total mass ratio of particles having a particle diameter of 106 μm or more and less than 212 μm is 50% by mass or more, the amount of fine powder and coarse powder is small, and therefore, polyethylene powder having excellent powder flowability is obtained. In addition, when a solvent such as liquid paraffin and polyethylene powder are kneaded, generation of lumps due to fine powder and generation of dissolution residues due to coarse powder that is difficult to dissolve can be suppressed.
On the other hand, when the total mass ratio of the particles having particle diameters of 106 μm or more and less than 212 μm is less than 75% by mass, the particles are easily packed in a mold at the time of compression molding using a press or a ram extruder, and thus the molded article tends not to have a molding strain.
As a method of controlling the total mass ratio of particles having a particle diameter of 106 μm or more and less than 212 μm in the polyethylene powder of the present embodiment to be in a range of 50 mass% or more and less than 75 mass%, a method of using a catalyst having a small particle diameter distribution as a catalyst used for polymerization of polyethylene can be mentioned. Further, the mass ratio of the particle diameter of the polyethylene powder can be controlled by adjusting the conditions in obtaining polyethylene by polymerization. For example, by lowering the polymerization pressure or shortening the residence time in the reactor, the total mass ratio of particles having a particle diameter of 106 μm or more and less than 212 μm can be controlled.
The total mass ratio of particles having a particle diameter of 106 μm or more and less than 212 μm can be calculated as follows: when the powder is classified by sieving with sieves having mesh sizes of 300. Mu.m, 212. Mu.m, 150. Mu.m, 106. Mu.m, 75. Mu.m and 53. Mu.m, the total mass of the powders on the sieves of 106. Mu.m and 150. Mu.m is divided by the total mass of the powders.
(average particle diameter)
From the viewpoint of processability and handleability, the polyethylene powder of the present embodiment has a preferable average particle diameter of 500 μm or less, more preferably 400 μm or less, and still more preferably 300 μm or less. The particle diameter at which 50% by mass of the polyethylene powder remaining on each sieve obtained above is accumulated from the side having a smaller sieve opening size is an average particle diameter.
(compact bulk density)
The polyethylene powder of the present embodiment preferably has a close bulk density of 0.50g/cm or more 3 And less than 0.65g/cm 3 More preferably 0.52g/cm or more 3 And less than 0.63g/cm 3 More preferably not less than 0.54g/cm 3 And less than 0.61g/cm 3 。
The pass through compact packing density was 0.50g/cm 3 As described above, since the aggregate of the polyethylene powder and the irregularly shaped polyethylene powder are small and have a nearly spherical shape, the powder flowability is excellent, and when compression molding is performed using a press or a ram extruder, the polyethylene powder is easily packed in a mold at the highest density, and the molding strain is hardly left in a molded body.
On the other hand, the passing compact density is less than 0.65g/cm 3 The powder has excellent solubility, can be processed at a lower temperature in a short time, and tends to be a polyethylene powder having a higher purity.
The polyethylene powder of the present embodiment is controlled to have a close bulk density of 0.50g/cm or more 3 And less than 0.65g/cm 3 The method within the range of (1) includes a method of synthesizing the catalyst using a general Ziegler-Natta catalyst or a metallocene catalyst, and a method of synthesizing the catalyst using a catalyst described later is particularly preferable.
In addition, the close bulk density of the polyethylene powder of the present embodiment can be controlled within the above range by suppressing the amount of heat generated by the rapid polymerization reaction occurring in the production of the polyethylene powder.
Specific examples of the method include the following methods: carrying out uniform continuous polymerization in a system in which ethylene gas, a solvent, a catalyst and the like are continuously supplied into a polymerization system, and unreacted ethylene gas and solvent are continuously discharged together with the produced polyethylene powder; alternately introducing a main catalyst and a cocatalyst from the same line to inhibit local rapid polymerization; a condenser for cooling the vaporized solvent and the like during the polymerization reaction by using a jacket so as not to charge the polyethylene powder, which is accompanied by the vaporized solvent and in which an abnormal reaction has occurred, into the polymerization reactor again; and so on.
(compact bulk Density/Loose bulk Density)
The value obtained by dividing the close bulk density by the loose bulk density (close bulk density/loose bulk density) of the polyethylene powder of the present embodiment is preferably 1.05 or more and less than 1.30, more preferably 1.07 or more and 1.27 or less, and still more preferably 1.09 or more and 1.24 or less.
When the value obtained by dividing the compact bulk density by the loose bulk density is in the range of 1.05 or more and less than 1.30, the fluidity of the polyethylene powder is excellent, the generation of voids can be further suppressed at the time of compression molding, and the mechanical properties of the molded article can be further improved.
The loose bulk density is a density measured in a state where the powder is loosely packed (without tapping) in a container having a predetermined volume.
The dense packing density is a density measured in a state where a container of a predetermined volume filled with a powder is repeatedly dropped (tapped) from a certain height at a certain speed and is densely filled until the bulk density of the powder in the container becomes substantially constant. Specifically, the close bulk density and the loose bulk density can be measured by the methods described in the examples described later.
A polyethylene powder having a value obtained by dividing the close bulk density by the loose bulk density within the above range can be obtained by controlling the particle size distribution, particle shape, and the like.
(Ca content)
The Ca content in the polyethylene powder of the present embodiment is preferably less than 10.0ppm, more preferably less than 8.0ppm, and still more preferably less than 6.0ppm.
When the Ca content is less than 10.0ppm, the polyethylene powder is obtained with less Ca elution and higher purity, and can be suitably used for containers or the like that are resistant to impurity elution.
Examples of the method for controlling the Ca content in the polyethylene powder of the present embodiment to be less than 10.0ppm include a method using a catalyst containing no Ca, a method not including a neutralizing agent such as calcium stearate, and a method not including an additive containing Ca.
The Ca content in the polyethylene powder can be measured by the method described in examples described later.
[ Process for producing polyethylene powder ]
The polyethylene powder of the present embodiment can be produced by a conventionally known polymerization method.
Examples of the polymerization method include, but are not limited to, methods in which ethylene or a monomer containing ethylene is polymerized (copolymerized) by a slurry polymerization method, a gas phase polymerization method, or a solution polymerization method. The slurry polymerization method which can effectively remove the heat of polymerization is particularly preferred. In the slurry polymerization process, an inert hydrocarbon medium can be used as a medium.
The inert hydrocarbon medium is not particularly limited, and examples thereof include: aliphatic hydrocarbons such as propane, butane, isobutane, pentane, isopentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as ethyl chloride, chlorobenzene, and dichloromethane; and mixtures thereof, and the like.
In the polymerization step of the polyethylene powder, an inert hydrocarbon medium having 6 to 10 carbon atoms is preferably used. If the number of carbon atoms is 6 or more, the low molecular weight component produced by side reactions during ethylene polymerization or polyethylene deterioration is relatively easily dissolved, and can be easily removed in the step of separating polyethylene from the polymerization medium. On the other hand, if the number of carbon atoms is 10 or less, there is a tendency that the adhesion of polyethylene powder to the reaction tank is suppressed, and the operation can be stably performed industrially.
The polymerization temperature in the production process of the polyethylene powder of the present embodiment is preferably 30 ℃ to 100 ℃, more preferably 35 ℃ to 95 ℃, and still more preferably 40 ℃ to 90 ℃. When the polymerization temperature is 30 ℃ or higher, the activity of the catalyst tends to be improved, the metal component as a catalyst residue remaining in the polyethylene can be reduced, and the catalyst tends to be industrially efficiently produced. On the other hand, if the polymerization temperature is 100 ℃ or lower, the adhesion to the reaction vessel can be suppressed, and the generation of polyethylene powder in which an abnormal reaction occurs in the solvent accompanying the vaporization can be suppressed, and stable operation tends to be possible.
The polymerization pressure in the production process of the polyethylene powder is preferably normal pressure or more and 2.0MPa or less, more preferably 0.1MPa or more and 1.5MPa or less, and still more preferably 0.1MPa or more and 1.0MPa or less.
The polymerization reaction can be carried out by any of a batch type, a semi-continuous type, and a continuous type, and it is particularly preferable to carry out the polymerization continuously. By continuously supplying ethylene gas, a solvent, a catalyst, etc. into the polymerization system and continuously discharging the ethylene gas, the solvent, the catalyst, etc. together with the produced polyethylene powder, it is possible to suppress a local high-temperature state caused by a rapid ethylene reaction and to suppress deactivation and side reactions of the catalyst, which tends to be more stable in the polymerization system.
Further, the polymerization can be carried out in 2 or more steps with different reaction conditions.
In the production process of the polyethylene powder of the present embodiment, polyethylene is produced by using the catalyst component. Examples of the catalyst component include, but are not limited to, ziegler-natta catalysts, metallocene catalysts, and phillips catalysts.
As the ziegler-natta catalyst, for example, the ziegler-natta catalyst described in the specification of japanese patent No. 5767202 can be suitably used, and as the metallocene catalyst, for example, the metallocene catalysts described in japanese patent laid-open nos. 2006-273977 and 4868853 can be suitably used, but not limited thereto. The catalyst component used in the production process of the polyethylene powder according to the present embodiment may contain a co-catalyst such as triisobutylaluminum and Tebbe reagent.
The average particle diameter of the catalyst is preferably 0.1 to 20 μm, more preferably 0.2 to 16 μm, and still more preferably 0.5 to 12 μm. When the average particle diameter of the catalyst is 0.1 μm or more, problems such as scattering and adhesion of the obtained polyethylene powder tend to be prevented. In addition, when the average particle diameter of the catalyst is 20 μm or less, there is a tendency that the polyethylene powder becomes excessively large and is precipitated in the polymerization system or causes a problem such as clogging of a line in the post-treatment step of the polyethylene powder. The catalyst preferably has a narrow particle size distribution, and can be removed from fine and coarse particles by sieving, centrifugal separation, or cyclone separation.
In the production process of the polyethylene powder of the present embodiment, it is preferable that the main catalyst and the cocatalyst are introduced alternately from the bottom of the polymerization reactor using the same introduction line. The method of addition is not limited, and the following operation is preferably repeated: the solid catalyst component as the main catalyst was continuously added for 1 minute and then stopped for 1 minute, and the co-catalyst such as triisobutylaluminum was continuously added for 1 minute and then stopped for 1 minute. The catalytic reaction starts by the contact of the main catalyst with the co-catalyst, and by alternately adding the main catalyst and the co-catalyst from the same introduction line, the contact of the main catalyst and the co-catalyst at high concentrations immediately after the addition can be reduced, and polyethylene can be produced without causing a rapid reaction.
In the production process of the polyethylene powder of the present embodiment, it is preferable to introduce ethylene gas from the bottom of the polymerization reactor. Further, for example, as described in the specification of German patent application laid-open No. 3127133, the intrinsic viscosity of the obtained polyethylene powder can be controlled by allowing hydrogen gas to be present in the polymerization system or changing the polymerization temperature. Further, by adding hydrogen as a chain transfer agent to the polymerization system, the intrinsic viscosity can be controlled within an appropriate range. When hydrogen is added to the polymerization system, the molar fraction of hydrogen is preferably 0 mol% or more and 30 mol% or less, more preferably 0 mol% or more and 25 mol% or less, and still more preferably 0 mol% or more and 20 mol% or less.
In addition to the above-described components, the present embodiment may contain other known components useful for the production of polyethylene.
In the production process of the polyethylene powder of the present embodiment, the deactivation of the catalyst system after use is not particularly limited, and it is preferably performed in a buffer tank before centrifugal separation of the polyethylene powder and the solvent. Examples of the chemical agent for deactivating the catalyst system include, but are not limited to, oxygen, water, alcohols, glycols, phenols, carbon monoxide, carbon dioxide, ethers, carbonyl compounds, alkynes, and the like.
The deactivation of the catalyst system is preferably carried out by introducing the alcohol into the buffer tank so that the alcohol reaches 5 to 20 mass% of the solvent amount. By adding a predetermined amount of alcohol to an inert hydrocarbon medium having 6 to 10 carbon atoms and stirring the mixture, it is possible to efficiently extract a metal component as a catalyst residue, an oligomer component produced by a side reaction, and the like.
In the production process of the polyethylene powder of the present embodiment, the separation of the solvent from the polyethylene powder is performed after the polymerization reaction.
Examples of the solvent separation method include decantation, centrifugation, and filter filtration, and centrifugation is preferable from the viewpoint of high separation efficiency between the polyethylene powder and the solvent.
The amount of the solvent contained in the polyethylene powder after the separation of the solvent is not particularly limited, and is preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 50% by mass or less, relative to the total mass of the polyethylene powder. By adjusting the solvent contained in the polyethylene powder to 70 mass% or less, metal components, oligomer components, and the like contained in the solvent tend not to remain in the polyethylene powder.
In the production process of the polyethylene powder of the present embodiment, it is preferable to perform a drying treatment after the solvent is separated.
The drying temperature is preferably 80 ℃ to 150 ℃, more preferably 90 ℃ to 140 ℃, and still more preferably 100 ℃ to 130 ℃.
If the drying temperature is 80 ℃ or higher, effective drying can be performed. On the other hand, if the drying temperature is 150 ℃ or lower, the polyethylene powder can be dried in a state in which thermal deterioration is suppressed. In the drying step, it is preferable that the polyethylene powder after polymerization is sprayed with a mixture (20/80 to 80/20 mass%) of water and alcohols at a concentration of 10m 3 Drying is carried out while blowing an inert gas at a flow rate of not less than one hour to remove the volatilized solvent. It is preferable to spray an aqueous solution containing an alcohol having a higher volatility to effectively remove the volatile matter and dry the aqueous solution, because it is possible to reduce low molecular weight components generated by side reactions, hydrochloric acid generated by deactivation of the catalyst, and the like.
(additives)
The polyethylene powder of the present embodiment may contain other known components useful for the production of polyethylene powder in addition to the above-described components.
The polyethylene powder according to the present embodiment may further contain an additive such as a neutralizing agent.
The neutralizing agent is used as a chlorine scavenger or a molding aid contained in the polyethylene powder. The neutralizing agent is not particularly limited, and examples thereof include: stearates of alkaline earth metals such as calcium, magnesium, and barium. The content of the neutralizing agent is not particularly limited, but is preferably 1000ppm or less, more preferably 600ppm or less, and further preferably 200ppm or less based on the total amount of the polyethylene powder, and in the polyethylene powder of the present embodiment, since there is a possibility that the additive may elute when the polyethylene powder and the molded article containing the polyethylene powder are used, it is preferable not to use the additive.
The content of the additive contained in the polyethylene of the present embodiment can be determined as follows: additives in polyethylene powder were extracted by soxhlet extraction using Tetrahydrofuran (THF) for 6 hours, and the extract was separated and quantified by liquid chromatography.
The polyethylene powder of the present embodiment may be blended with polyethylenes having different intrinsic viscosities, molecular weight distributions, and the like, or may be blended with other resins such as low density polyethylene, linear low density polyethylene, polypropylene, polystyrene, and the like.
[ Molding article ]
The polyethylene powder of the present embodiment can be applied to various uses by various processing methods.
The molded article of the present embodiment can be produced by molding the polyethylene powder of the present embodiment, and the molded article is high in purity and excellent in heat resistance, and therefore can be suitably used as a microporous film, a fiber, a sheet-like or a block-like molded article.
Examples of such molded articles include: secondary battery separators, particularly lithium ion secondary battery separators, lead storage battery separators, high-strength fibers, and the like.
Further, the ultra-high molecular weight polyethylene has excellent characteristics of wear resistance, high slidability, high strength and high impact resistance, and can be used for gear wheels, rollers, curtain rails, guide rails for marble, lining sheets for storage silos for grains and the like, slip-increasing coatings for rubber products and the like, lining materials for heavy machinery such as ski materials, ski soles, trucks, forklifts and the like, by solid-state molding such as extrusion molding, press molding, cutting and the like, utilizing the characteristics of ultra-high molecular weight polyethylene as its characteristics.
The molded article obtained by sintering the polyethylene powder of the present embodiment can be used for, for example, a filter, a dust collecting material, a suction conveying sheet, and the like.
Further, the present invention can be suitably used for applications requiring cleanliness, such as containers for storing high-purity chemicals, ultrapure water, and the like (hereinafter, referred to as contact objects), and filters for filtration.
[ examples ]
The present embodiment will be described in detail below with reference to specific examples and comparative examples, but the present embodiment is not limited to the following examples and comparative examples.
The measurement methods of various physical properties and characteristics are as follows.
[ measuring method and evaluation method for various physical Properties and Properties ]
(1) measurement of intrinsic viscosity [. Eta. ])
To 20mL of decalin (containing 1g/L of 2, 6-di-t-butyl-4-methylphenol) was added 10mg of polyethylene powder, and the mixture was stirred at 150 ℃ for 2 hours to dissolve the polymer. The solution was measured for the drop time (ts) between calibration lines using a Cannon-Fenske viscometer in a constant temperature bath at 135 ℃. Similarly, 3-point solutions were prepared by changing the mass of the polyethylene powder, and the falling time was measured.
The falling time (tb) of only decalin without polyethylene powder added was measured as a blank. The reduced viscosities (. Eta.sp/C) of the polymers obtained by the following formula were plotted, respectively, to derive a linear equation of the concentration (. Eta.sp/C) and the reduced viscosity (. Eta.sp/C) of the polymer, and to obtain an intrinsic viscosity (. Eta.) extrapolated to a concentration of 0.
(ηsp/C)＝(ts/tb-1)/C
((2) Heat flow 60 minutes after switching to oxygen in the Oxidation Induction time measurement)
The heat flow 60 minutes after switching to oxygen in the oxidative induction time determination was determined by the oxidative induction time test according to ISO11357-6 (2018).
The measurement was carried out by using a differential scanning calorimeter (product name: DSC-60Plus, manufactured by Shimadzu corporation).
First, 5mg of alumina was placed in an aluminum pan for DSC measurement as a reference. It was placed on the left side of a DSC-60Plus oven, and on the right side of the oven was placed an aluminum pan into which 5mg (precision weighing) of polyethylene powder was placed. While nitrogen gas was flowed at 25 mL/min in the furnace, the temperature was raised from 40 ℃ to 150 ℃ at a temperature raising rate of 25 ℃/min, and the mixture was left standing for 5 minutes in this state, and then the nitrogen gas was switched to oxygen gas, and the measurement was started.
The sampling interval at the time of measurement was set to 0.5 second.
The value obtained by subtracting the heat flow at the time of switching nitrogen to oxygen from the heat flow after 60 minutes was taken as the heat flow after 60 minutes in the oxidation induction time measurement.
(3) contents of Mg, ti, al and Ca)
Polyethylene powder was decomposed under pressure using a microwave decomposition apparatus (model ETHOS TC, manufactured by Milestone General company), and the concentrations of elements of magnesium, titanium, aluminum, and calcium were measured as the metal contents in the polyethylene powder by ICP-MS (inductively coupled plasma mass spectrometer, model X series X7, manufactured by seimer feishell scientific) by an internal standard method.
((4) alpha-olefin content)
The alpha-olefin content of the polyethylene powder was determined according to the method disclosed in Macromolecules,10,773 (1977) of g.j. ray et al, using a method of reducing the ethylene content by mixing 13 The alpha-olefin content was calculated from the area intensity of a methylene carbon signal observed in a C-NMR spectrum.
Measurement device: ECS-500 manufactured by Nippon electronics Co., ltd
And (3) observing a nucleus: 13 C
observation frequency: 100.53MHz
Pulse width: 45 ° (7.5 microseconds)
Pulse program: single pulse dec
PD: 5 seconds
Measuring temperature: 130 deg.C
Cumulative number of times: 30000 times or more
Reference: PE (-eee-) signal, 29.9ppm
Solvent: o-dichlorobenzene-d 4
Sample concentration: 5 to 10% by weight
Dissolution temperature: 130-140 deg.C
(5) maximum rate of increase in oxidized weight)
Using a thermogravimetric analyzer (manufactured by perkin elmer, trade name "Pyris1 TGA"), at a sample weight: 5mg, oxygen flow: 10 mL/min, temperature elevation rate: the temperature was raised from room temperature to 200 ℃ at 30 ℃/min, and the temperature was maintained for 1 hour, and then the weight increase rate was measured. It was confirmed that the weight of the polyethylene powder increased most due to oxidation within about 30 minutes from the start of the measurement and then gradually decreased. The ratio of the maximum increase in weight was defined as the maximum rate of increase in oxidation weight.
(6) Total mass ratio of particles having particle diameters of 106 to 212 μm inclusive, average particle diameter)
The total mass ratio of particles having a particle diameter of 106 μm or more and less than 212 μm was measured as follows.
100g of polyethylene powder was weighed into a 200mL plastic cup, 1g of carbon black was added, and the mixture was sufficiently stirred with a spatula. The polyethylene powder after stirring was passed through a sieve having mesh sizes of 300. Mu.m, 212. Mu.m, 150. Mu.m, 106. Mu.m, 75. Mu.m, and 53 μm in accordance with JIS Z8801 to classify the powder. The ratio obtained by dividing the total mass of the powders on the sieves of 106 μm and 150 μm by the total mass of the powders was defined as the total mass ratio (mass%) of the particles having a particle diameter of 106 μm or more and less than 212 μm.
In addition, in a cumulative curve obtained by accumulating the mass of the polyethylene powder remaining on each sieve obtained at this time from the side having a smaller sieve opening size, the particle diameter at which 50 mass% is reached is taken as the average particle diameter.
(7) compact bulk Density/Loose bulk Density)
The measurements of the close bulk density and the loose bulk density were carried out using a powder tester PT-X type (manufactured by Mikroo K.K.).
Polyethylene powder was made to flow down to 100cm of stainless steel by vibrating the sample supply apparatus 3 In a cylindrical container, until the container was filled with the polyethylene powder, excess polyethylene powder was scraped off from the container using a blade, and the measured density was taken as a loose bulk density (g/cm) 3 )。
In addition, the stainless steel is made to be 100cm 3 The cylindrical container is covered with a cover, and the sample supplying device is vibrated to supply the sampleThe polyethylene powder was tapped under conditions of a stroke length (tap height) of 18mm, a tap speed of 60 times/min, and a tap frequency of 180 times while flowing down. Then, excess polyethylene powder was scraped off from the container using a blade, and the measured density was regarded as a close bulk density (g/cm) 3 )。
The value of the close bulk density/loose bulk density is obtained by dividing the measured value of the close bulk density measured in the above manner by the measured value of the loose bulk density measured in the above manner.
(whiteness of molded article (8))
A molded article was produced according to ISO11542-2 by preheating at 220 ℃ and 5MPa for 5 minutes and then heating and compressing at 220 ℃ and 10MPa for 45 minutes. Then, annealing was performed at 100 ℃ for 24 hours.
The whiteness of the molded article was measured according to the measurement standard CIE/ASTM E313-96 using a color difference meter CR-20 (manufactured by Konika Meinenda Co., ltd.) and evaluated.
The evaluation criteria are as follows.
Good particles 82300 and the whiteness of the molded article is 95 or more.
Delta 8230and the whiteness of the molded article is 90 to 95 inclusive.
X 8230and the whiteness of the molded article is less than 90.
The following results were obtained: the polyethylene powder of the examples had high whiteness, and was excellent in oxidation/deterioration resistance even when heated and compressed for a long time, and was free from discoloration and excellent in whiteness.
(9) molecular weight reduction rate in kneading)
A slurry liquid was prepared by mixing 30 parts by mass of polyethylene powder and 70 parts by mass of liquid paraffin, assuming that the total amount of polyethylene powder and liquid paraffin was 100 parts by mass.
The obtained slurry-like liquid was fed into a twin-screw extruder through a feeder and kneaded at 230 ℃ for 30 minutes, thereby obtaining a polyethylene gel. The resulting polyethylene gel was extruded from a T-die provided at the tip of an extruder, and immediately cooled and solidified by a casting roll cooled to 25 ℃ to form a gel-like sheet. The gel-like sheet was stretched to 7 × 7 times at 120 ℃ using a simultaneous biaxial stretcher, to thereby obtain a stretched film. Then, the stretched film was immersed in hexane, and the liquid paraffin was completely extracted and removed, followed by vacuum drying at 50 ℃ for 12 hours.
The molecular weight reduction was calculated by the following formula: the intrinsic viscosity of the raw material polyethylene powder minus the intrinsic viscosity of the stretched film is divided by the intrinsic viscosity of the raw material polyethylene powder, and the resultant value is multiplied by 100.
{ [ (intrinsic viscosity of polyethylene powder) - (intrinsic viscosity of stretched film) ]/(intrinsic viscosity of polyethylene powder) } × 100 (%)
The molecular weight reduction rate was evaluated according to the following criteria.
The evaluation criteria are as follows.
Good quality 823080, and the molecular weight reduction rate is 10% or less.
Delta 8230and the molecular weight reduction rate is greater than 10% and less than or equal to 15%.
X 8230and the molecular weight reduction rate is more than 15%.
((10) cleanliness
500mL of ultrapure water (purified using Trepure LV-10T (manufactured by Toray corporation) (registered trademark)) was charged into a 1L round glass container, and the container was covered with a cap, washed with shaking for 30 seconds, and then drained. This shaking cleaning was repeated 5 times.
The vessel was again filled with 500mL of ultrapure water, a molded body having a width of 2cm, a length of 15cm and a thickness of 4mm manufactured in accordance with ISO11542-2 was introduced thereinto, the lid was closed, the vessel was shaken for 30 seconds, and then drained. This shaking cleaning was repeated 5 times.
Next, 500mL of ultrapure water was added to a 1L round glass vessel containing the molded article, and the mixture was shaken at 70 ℃ for 4 weeks. After 4 weeks, 5mL of the solution was taken out of the filling water, and the number of fine particles having a particle size of 0.1 μm or more that had been leached out was measured by a particle counter (KL-22 (manufactured by RION Co., ltd.).
The number of fine particles contained in water was determined by the following equation, and this was defined as the degree of cleanliness.
The calculation formula and evaluation criteria are as follows.
Cleanliness: number of fine particles in water (one/mL) = { (number of counts (one)) × (amount of ultrapure water 100 (mL)) }/{ sampling amount 5 (mL) × container capacity 200 (mL) }
Good quality 823060%, less than 40/mL.
Delta 823040/mL and less than 70.
X 8230and 70 pieces/mL.
[ (preparation example) Synthesis of catalyst ]
(preparation of solid catalyst component [ A ]
1600mL of hexane was added to an 8L stainless steel autoclave which had been sufficiently purged with nitrogen. While stirring at 10 ℃ for 4 hours, 800mL of a 1mol/L titanium tetrachloride hexane solution and 800mL of a 1mol/L titanium tetrachloride hexane solution having a composition represented by the formula AlMg were added simultaneously 5 (C 4 H 9 ) 11 (OSiH) 2 Hexane solution of the indicated organomagnesium compound. After the addition, the temperature was slowly raised, and the reaction was continued at 10 ℃ for 1 hour.
After the reaction was completed, 1600mL of the supernatant was removed, and the reaction solution was washed 5 times with 1600mL of hexane, whereby a solid catalyst component [ A ] was prepared.
The amount of titanium contained in 1g of the solid catalyst component [ A ] was 3.05 mmol.
(preparation of solid catalyst component [ B ]
< (1) Synthesis of raw Material (b-1)
2000mL of 1mol/L Mg was charged into an 8L stainless steel autoclave sufficiently purged with nitrogen 6 (C 4 H 9 ) 12 Al(C 2 H 5 ) 3 The hexane solution (corresponding to 2000 mmol in terms of magnesium and aluminum) of (1) was added dropwise over 3 hours while stirring at 50 ℃ to 146mL of a 5.47mol/L n-butanol hexane solution, and after completion, the line was purged with 300mL of hexane. Then, stirring was continued at 50 ℃ for 2 hours. After the reaction was completed, the solution cooled to room temperature was used as the raw material (b-1). The raw material (b-1) was 0.704mol/L in terms of the total concentration of magnesium and aluminum.
< (2) Synthesis of raw Material (b-2)
2000mL of 1mol/L Mg was charged into an 8L stainless steel autoclave sufficiently purged with nitrogen 6 (C 4 H 9 ) 12 Al(C 2 H 5 ) 3 The hexane solution (equivalent to 2000 mmol in terms of magnesium and aluminum) was added dropwise to 240mL of a hexane solution of 8.33mol/L methylhydrogenpolysiloxane (manufactured by shin-Etsu chemical Co., ltd.) over 3 hours while stirring at 80 ℃ and after completion, the line was purged with 300mL of hexane. Then, stirring was continued at 80 ℃ for 2 hours. After the reaction was completed, the solution cooled to room temperature was used as the raw material (b-2). The raw material (b-2) was 0.786mol/L in terms of the total concentration of magnesium and aluminum.
< (3) (B-1) Synthesis of vector
Into an 8L stainless steel autoclave sufficiently purged with nitrogen, 1000mL of a 1mol/L hexane solution of hydroxytrichlorosilane was charged, 1340mL of a hexane solution of an organomagnesium compound of the raw material (b-1) (corresponding to 943 mmol of magnesium) was added dropwise at 65 ℃ over 3 hours, and the reaction was continued while stirring at 65 ℃ for 1 hour. After completion of the reaction, the supernatant was removed and washed 4 times with 1800mL of hexane to obtain (B-1) a carrier. The carrier was analyzed, and as a result, magnesium contained in an amount of 7.5 mmol per 1g of the solid.
< (4) preparation of solid catalyst component [ B ]
To 1970mL of a hexane slurry containing 110g of the above (B-1) carrier were added 103mL of a 1mol/L hexane solution of titanium tetrachloride and 131mL of the raw material (B-2) simultaneously over 3 hours while stirring at 10 ℃.
After the addition, the reaction was continued at 10 ℃ for 1 hour. After the completion of the reaction, the supernatant liquid was removed and washed 4 times with hexane to remove the unreacted raw material component, thereby preparing a solid catalyst component [ B ].
[ example 1]
(production of polyethylene)
Hexane, ethylene, 1-butene, hydrogen, and a catalyst were continuously supplied to a vessel type 300L polymerization reactor equipped with a stirring device.
Hexane was supplied at 80L/hr from the bottom of the polymerization reactor.
Ethylene gas was supplied from the bottom of the polymerization reactor to maintain the polymerization pressure at 0.3MPa.
1-butene and hydrogen were supplied to the gas phase portion in the upper part of the polymerization reactor in such a manner that the gas phase concentration of 1-butene relative to ethylene was 0.25 mol% and the gas phase concentration of hydrogen relative to ethylene and 1-butene was 11.2 mol%.
The solid catalyst component [ A ] and triisobutylaluminum as a co-catalyst were used as a catalyst. The solid catalyst component [ A ] was added at a rate of 0.2 g/hr and triisobutylaluminum was added at a rate of 10 mmol/hr alternately from the bottom of the polymerization reactor using the same introduction line. As the addition method, the following operations were repeatedly performed: the solid catalyst component [ A ] was continuously added for 1 minute and then stopped for 1 minute, and triisobutylaluminum was continuously added for 1 minute and then stopped for 1 minute.
The polymerization temperature was maintained at 78 ℃ by passing through a condenser which was cooled with a jacket and cooled with vaporized solvent and the like. In addition, a filter having a mesh size of 75 μm was provided in a pipe for returning the solvent cooled by the condenser to the polymerization reactor so that the polyethylene powder mixed in the solvent was not charged into the polymerization reactor again.
The catalyst activity was 12000 g-PE/g-solid catalyst component [ A ], and the slurry concentration was 27%.
The resulting polymerization slurry was continuously withdrawn into a flash tank with a stirring device so that the liquid level of the polymerization reactor was kept constant, and unreacted ethylene and hydrogen were separated.
Next, the polymerization slurry was continuously drawn out into a buffer tank with a stirring device so that the liquid level of the flash tank was kept constant. Ethanol was introduced into a buffer tank so that the ethanol reached 10 mass% of the solvent amount, and stirred for 1.5 hours.
Next, the polymerization slurry was continuously sent to a centrifuge so that the liquid level height of the buffer tank was kept constant, and the polyethylene was separated from the solvent and the like other than the polyethylene, thereby obtaining polyethylene powder. The content of the solvent and the like relative to the polyethylene in this case was 55%.
The isolated polyethylene powder was dried at 105 ℃ for 2 hours. It is noted thatSteam of water and isopropyl alcohol (70 mass%/30 mass%) was sprayed to the polyethylene powder after polymerization at a rate of 15m 3 The drying step was carried out while blowing nitrogen gas at a flow rate per hour to remove the volatilized solvent. With respect to the obtained polyethylene powder, powder which did not pass through the sieve was removed using a sieve having a mesh size of 425 μm, thereby obtaining polyethylene powder of example 1. The physical properties of the obtained polyethylene powder are shown in table 1.
[ example 2]
The polyethylene powder of example 2 was obtained in the same manner as in example 1 except that hydrogen gas was introduced so as to have a gas phase concentration of 10.6 mol% relative to ethylene without introducing 1-butene in the polymerization step and the solid catalyst component [ B ] was used in place of the solid catalyst component [ a ]. The catalyst activity was 12000 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 29%.
[ example 3]
The polyethylene powder of example 3 was obtained in the same manner as in example 1, except that the polymerization temperature was set to 76 ℃ and that hydrogen gas was introduced so that the gas phase concentration with respect to ethylene was 0.18 mol% without introducing 1-butene in the polymerization step. The catalyst activity was 16000 g-PE/g-solid catalyst component [ A ], and the slurry concentration was 28%.
[ example 4]
The polyethylene powder of example 4 was obtained in the same manner as in example 1, except that the polymerization temperature was set to 71 degrees centigrade, the polymerization pressure was set to 0.35MPa, hydrogen was introduced so that the gas phase concentration with respect to ethylene was 0.20 mol%, and the solid catalyst component [ B ] was used instead of the solid catalyst component [ a ] in the polymerization step. The catalyst activity was 20000 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 25%.
[ example 5]
The polyethylene powder of example 5 was obtained in the same manner as in example 4, except that 150ppm of calcium stearate was introduced into the polyethylene powder in the polymerization step. The catalyst activity was 20000 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 25%.
[ example 6]
The polyethylene powder of example 6 was obtained by the same operation as in example 1, except that the polymerization temperature was set to 65 ℃ and the polymerization pressure was set to 0.35MPa, that 1-butene was introduced so as to have a gas phase concentration of 0.35 mol% with respect to ethylene, that hydrogen was introduced so as to have a gas phase concentration of 0.01 mol% with respect to ethylene and 1-butene, that the solid catalyst component [ B ] was used instead of the solid catalyst component [ a ], and that ethanol was not introduced into the buffer tank in the polymerization step. The catalyst activity was 10000 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 25%.
[ example 7]
The polyethylene powder of example 7 was obtained in the same manner as in example 1 except that the polymerization temperature was set to 57 ℃ and the polymerization pressure was set to 0.36MPa in the polymerization step, and the solid catalyst component [ B ] was used instead of the solid catalyst component [ a ] without introducing 1-butene and hydrogen. The catalyst activity was 8000 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 20%.
Comparative example 1
A polyethylene powder of comparative example 1 was obtained in the same manner as in example 1, except that the polymerization temperature was set to 85 ℃ and the polymerization pressure was set to 0.90MPa, 1-butene was introduced so as to have a gas phase concentration of 3.7 mol% with respect to ethylene, and hydrogen was introduced so as to have a gas phase concentration of 24.2 mol% with respect to ethylene and 1-butene in the polymerization step. The catalyst activity was 50000 g-PE/g-solid catalyst component [ A ], and the slurry concentration was 27%.
Comparative example 2
The polyethylene powder of comparative example 2 was obtained in the same manner as in comparative example 1, except that the polymerization temperature was set to 85 ℃ and the polymerization pressure was set to 0.85MPa, and hydrogen gas was introduced so that the gas phase concentration with respect to ethylene was 33.2 mol% without introducing 1-butene in the polymerization step. The catalyst activity was 51000 g-PE/g-solid catalyst component [ A ], and the slurry concentration was 26%.
Comparative example 3
A polyethylene powder of comparative example 3 was obtained in the same manner as in example 1, except that 1-butene was introduced so that the polymerization temperature was 61 ℃ and the polymerization pressure was 0.32MPa and the gas phase concentration of ethylene was 6.5 mol%, and the solid catalyst component [ B ] was used instead of the solid catalyst component [ a ] without introducing hydrogen gas in the polymerization step. The catalyst activity was 10000 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 25%.
Comparative example 4
The polyethylene powder of comparative example 4 was obtained in the same manner as in example 1, except that 150ppm of pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ] was added as an antioxidant.
Comparative example 5
In the polymerization step, the polyethylene powder of comparative example 5 was obtained by the same operation as in example 1, except that the polymerization temperature was set to 45 ℃, the polymerization pressure was set to 0.28MPa, 1-butene was introduced so that the concentration of the gas phase with respect to ethylene was 0.35 mol%, hydrogen was introduced so that the concentration of the gas phase with respect to ethylene and 1-butene was 0.23 mol%, the solid catalyst component [ B ] was used in place of the solid catalyst component [ a ], the solid catalyst component [ B ] was introduced at a rate of 0.3 g/hr, triisobutylaluminum was introduced at a rate of 15 mmol/hr, and ethanol was not introduced into the buffer tank. The catalyst activity was 4500 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 35%.
Comparative example 6
A polyethylene powder of comparative example 6 was obtained in the same manner as in example 6, except that the solid catalyst component [ B ] and triisobutylaluminum as a co-catalyst were continuously added from separate introduction lines in the polymerization step and ethanol was not introduced into the buffer tank. The catalyst activity was 10000 g-PE/g-solid catalyst component [ B ], and the slurry concentration was 25%.
Comparative example 7
In the polymerization step, the solid catalyst component [ A ] was continuously added from a separate introduction line]And triisobutylaluminum as a co-catalyst, temperature-adjusted by jacket cooling only without using a condenser, sprayed with water alone without introducing ethanol into a buffer tank, and heated at 3m 3 A polyethylene powder of comparative example 7 was obtained in the same manner as in example 3, except that nitrogen gas was blown per hour. The catalyst activity was 14500 g-PE/g-solid catalyst constituent [ B ]]The slurry concentration was 28%.
Industrial applicability
The polyethylene powder of the present invention is excellent in molecular weight stability even under processing conditions under severer conditions, and a molded article containing the polyethylene powder is excellent in whiteness and cleanness, and therefore has high industrial applicability as a material for various films, sheets, microporous films, fibers, foams, pipes, and the like, which are required to have high purity.
Claims (10)
1. A polyethylene powder, wherein the intrinsic viscosity of the polyethylene powder is 3.0dl/g or more and less than 30.0dl/g, and
the heat flow of the polyethylene powder 60 minutes after switching to oxygen was 0.03mW or more and less than 0.25mW in the measurement of the oxidation induction time according to ISO11357-6 (2018) (150 ℃, under oxygen, sample mass 5 mg).
2. Polyethylene powder according to claim 1 wherein the Mg content of the polyethylene powder is less than 10.0ppm.
3. Polyethylene powder according to claim 1 or 2 wherein the content of Ti in the polyethylene powder is less than 3.0ppm.
4. Polyethylene powder according to any one of claims 1 to 3 wherein the Al content in the polyethylene powder is less than 8.0ppm.
5. Polyethylene powder according to any one of claims 1 to 4 wherein the content of alpha-olefin in the polyethylene powder is less than 0.10 mol%.
6. Polyethylene powder according to any one of claims 1 to 5 wherein the maximum weight gain of the polyethylene powder when heated at 200 ℃ for 1 hour in air is less than 2.0%.
7. The polyethylene powder according to any one of claims 1 to 6, wherein the total mass ratio of particles having a particle diameter of 106 μm or more and less than 212 μm in the polyethylene powder is 50% by mass or more and less than 75% by mass.
8. Polyethylene powder according to any one of claims 1 to 7 wherein the polyethylene powder has a close bulk density of 0.50g/cm or more 3 And less than 0.65g/cm 3 And are each and every
A value (close bulk density/loose bulk density) obtained by dividing the close bulk density of the polyethylene powder by a loose bulk density is 1.05 or more and less than 1.30.
9. Polyethylene powder according to any one of claims 1 to 8 wherein the Ca content of the polyethylene powder is less than 10ppm.
10. A molded article comprising the polyethylene powder according to any one of claims 1 to 9.
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| JP2021090003A JP2022182443A (en) | 2021-05-28 | 2021-05-28 | Polyethylene powder and compact |
| JP2021-090003 | 2021-05-28 |
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| JP6878841B2 (en) | 2016-03-11 | 2021-06-02 | 東ソー株式会社 | Separator made of ultra high molecular weight polyethylene composition |
| JP6195403B1 (en) | 2016-03-25 | 2017-09-13 | 旭化成株式会社 | Ultra high molecular weight ethylene copolymer powder and molded product using ultra high molecular weight ethylene copolymer powder |
| JP2018145412A (en) | 2017-03-07 | 2018-09-20 | 東ソー株式会社 | Ultra-high-molecular-weight polyethylene particle and molded body consisting of the same |
| JP7353066B2 (en) | 2018-07-13 | 2023-09-29 | 旭化成株式会社 | polyethylene fiber |
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- 2021-05-28 JP JP2021090003A patent/JP2022182443A/en active Pending
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- 2022-05-20 CN CN202210549232.7A patent/CN115403688A/en active Pending
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| US20150299903A1 (en) * | 2014-04-18 | 2015-10-22 | Asahi Kasei Chemicals Corporation | Polyethylene Powder for Fiber, Fiber, and Article |
| CN107438631A (en) * | 2016-03-25 | 2017-12-05 | 旭化成株式会社 | Ultra-high-molecular-weight polyethylene analog copolymer powder and the formed body for having used ultra-high-molecular-weight polyethylene analog copolymer powder |
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| WO2020179650A1 (en) * | 2019-03-01 | 2020-09-10 | 旭化成株式会社 | Polyethylene powder and shaped object obtained by shaping same |
| WO2020189443A1 (en) * | 2019-03-18 | 2020-09-24 | 旭化成株式会社 | Polyethylene powder and molded body thereof |
| CN112724302A (en) * | 2019-10-28 | 2021-04-30 | 住友化学株式会社 | Ethylene-alpha-olefin copolymer, process for producing the same, ethylene resin composition, and film |
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| JP2022182443A (en) | 2022-12-08 |
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