CN106589515B - Ethylene polymer composition with broad molecular weight distribution, process for producing the same and use thereof - Google Patents
Ethylene polymer composition with broad molecular weight distribution, process for producing the same and use thereof Download PDFInfo
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- CN106589515B CN106589515B CN201510683783.2A CN201510683783A CN106589515B CN 106589515 B CN106589515 B CN 106589515B CN 201510683783 A CN201510683783 A CN 201510683783A CN 106589515 B CN106589515 B CN 106589515B
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- 239000000203 mixture Substances 0.000 title claims abstract description 59
- 229920000573 polyethylene Polymers 0.000 title claims abstract description 38
- 238000009826 distribution Methods 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims abstract description 13
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 50
- 239000005977 Ethylene Substances 0.000 claims abstract description 50
- 229920000642 polymer Polymers 0.000 claims abstract description 41
- 238000004519 manufacturing process Methods 0.000 claims abstract description 26
- 238000012360 testing method Methods 0.000 claims abstract description 11
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 claims description 30
- 239000007789 gas Substances 0.000 claims description 30
- 239000001257 hydrogen Substances 0.000 claims description 23
- 229910052739 hydrogen Inorganic materials 0.000 claims description 23
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 21
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 239000003054 catalyst Substances 0.000 claims description 14
- 239000002002 slurry Substances 0.000 claims description 13
- 239000012530 fluid Substances 0.000 claims description 10
- 239000012190 activator Substances 0.000 claims description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 239000001294 propane Substances 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 230000001684 chronic effect Effects 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 239000010936 titanium Substances 0.000 claims description 5
- VOITXYVAKOUIBA-UHFFFAOYSA-N triethylaluminium Chemical compound CC[Al](CC)CC VOITXYVAKOUIBA-UHFFFAOYSA-N 0.000 claims description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 4
- SXSVTGQIXJXKJR-UHFFFAOYSA-N [Mg].[Ti] Chemical compound [Mg].[Ti] SXSVTGQIXJXKJR-UHFFFAOYSA-N 0.000 claims description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 238000006116 polymerization reaction Methods 0.000 abstract description 36
- 239000004711 α-olefin Substances 0.000 abstract description 12
- 125000004432 carbon atom Chemical group C* 0.000 abstract description 8
- 229920001577 copolymer Polymers 0.000 abstract description 5
- 229920001903 high density polyethylene Polymers 0.000 abstract description 2
- 239000004700 high-density polyethylene Substances 0.000 abstract description 2
- 229920001519 homopolymer Polymers 0.000 abstract description 2
- 239000012071 phase Substances 0.000 description 20
- -1 Polyethylene Polymers 0.000 description 13
- 239000004698 Polyethylene Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- 238000011065 in-situ storage Methods 0.000 description 6
- 239000000178 monomer Substances 0.000 description 6
- 239000000654 additive Substances 0.000 description 5
- 229910052723 transition metal Inorganic materials 0.000 description 5
- 150000003624 transition metals Chemical class 0.000 description 5
- 238000012685 gas phase polymerization Methods 0.000 description 4
- 239000002685 polymerization catalyst Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- VBICKXHEKHSIBG-UHFFFAOYSA-N 1-monostearoylglycerol Chemical compound CCCCCCCCCCCCCCCCCC(=O)OCC(O)CO VBICKXHEKHSIBG-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 239000012429 reaction media Substances 0.000 description 2
- RELMFMZEBKVZJC-UHFFFAOYSA-N 1,2,3-trichlorobenzene Chemical compound ClC1=CC=CC(Cl)=C1Cl RELMFMZEBKVZJC-UHFFFAOYSA-N 0.000 description 1
- 239000001692 EU approved anti-caking agent Substances 0.000 description 1
- UAUDZVJPLUQNMU-UHFFFAOYSA-N Erucasaeureamid Natural products CCCCCCCCC=CCCCCCCCCCCCC(N)=O UAUDZVJPLUQNMU-UHFFFAOYSA-N 0.000 description 1
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- 239000006057 Non-nutritive feed additive Substances 0.000 description 1
- 239000000026 Pentaerythritol tetranitrate Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- BGYHLZZASRKEJE-UHFFFAOYSA-N [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxy]-2,2-bis[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxymethyl]propyl] 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate Chemical compound CC(C)(C)C1=C(O)C(C(C)(C)C)=CC(CCC(=O)OCC(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)=C1 BGYHLZZASRKEJE-UHFFFAOYSA-N 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 125000005234 alkyl aluminium group Chemical group 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- ZXVOCOLRQJZVBW-UHFFFAOYSA-N azane;ethanol Chemical compound N.CCO ZXVOCOLRQJZVBW-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002902 bimodal effect Effects 0.000 description 1
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 description 1
- 239000008116 calcium stearate Substances 0.000 description 1
- 235000013539 calcium stearate Nutrition 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- UAUDZVJPLUQNMU-KTKRTIGZSA-N erucamide Chemical compound CCCCCCCC\C=C/CCCCCCCCCCCC(N)=O UAUDZVJPLUQNMU-KTKRTIGZSA-N 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 229920001973 fluoroelastomer Polymers 0.000 description 1
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 1
- YQEMORVAKMFKLG-UHFFFAOYSA-N glycerine monostearate Natural products CCCCCCCCCCCCCCCCCC(=O)OC(CO)CO YQEMORVAKMFKLG-UHFFFAOYSA-N 0.000 description 1
- SVUQHVRAGMNPLW-UHFFFAOYSA-N glycerol monostearate Natural products CCCCCCCCCCCCCCCCC(=O)OCC(O)CO SVUQHVRAGMNPLW-UHFFFAOYSA-N 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 229910052809 inorganic oxide Inorganic materials 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 238000001225 nuclear magnetic resonance method Methods 0.000 description 1
- 239000002667 nucleating agent Substances 0.000 description 1
- FATBGEAMYMYZAF-KTKRTIGZSA-N oleamide Chemical compound CCCCCCCC\C=C/CCCCCCCC(N)=O FATBGEAMYMYZAF-KTKRTIGZSA-N 0.000 description 1
- FATBGEAMYMYZAF-UHFFFAOYSA-N oleicacidamide-heptaglycolether Natural products CCCCCCCCC=CCCCCCCCC(N)=O FATBGEAMYMYZAF-UHFFFAOYSA-N 0.000 description 1
- 230000003534 oscillatory effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000000518 rheometry Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000012748 slip agent Substances 0.000 description 1
- WXMKPNITSTVMEF-UHFFFAOYSA-M sodium benzoate Chemical compound [Na+].[O-]C(=O)C1=CC=CC=C1 WXMKPNITSTVMEF-UHFFFAOYSA-M 0.000 description 1
- 235000010234 sodium benzoate Nutrition 0.000 description 1
- 239000004299 sodium benzoate Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- MCULRUJILOGHCJ-UHFFFAOYSA-N triisobutylaluminium Chemical compound CC(C)C[Al](CC(C)C)CC(C)C MCULRUJILOGHCJ-UHFFFAOYSA-N 0.000 description 1
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
Classifications
-
- 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
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/08—Copolymers of ethene
- C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
- C08L23/0815—Copolymers of ethene with aliphatic 1-olefins
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L9/00—Rigid pipes
- F16L9/12—Rigid pipes of plastics with or without reinforcement
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2203/00—Applications
- C08L2203/18—Applications used for pipes
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The invention discloses an ethylene polymer composition with wide molecular weight distribution, a production method and application thereof. The composition is multimodal in terms of molecular weight distribution and/or comonomer distribution, and the molecular weight distribution is 8-40; the composition comprises a component A and a component B, wherein the component A is a homopolymer of ethylene or a copolymer of ethylene and one or more alpha-olefins with 4-10 carbon atoms, and the component B is a copolymer of ethylene and one or more alpha-olefins with 4-10 carbon atoms, and the weight average molecular weight of the component B is higher than that of the component A. The present invention provides an ethylene polymer composition prepared by a stepwise process, a first polymerization zone and a second polymerization zone being connected in series, a polymer formed in the first polymerization zone being present in the second polymerization zone; the notch test result of the slow crack growth resistance of the ethylene polymer composition obtained by the invention exceeds 5000 hours, and the ethylene polymer composition can be used for preparing high-density polyethylene pipes.
Description
Technical Field
The invention belongs to the technical field of macromolecules, and particularly relates to an ethylene polymer composition with wide molecular weight distribution, a production method and application thereof.
Background
Polyethylene pipe materials are often used for various purposes, such as fluid transport, i.e. the transport of liquids or gases (e.g. water and natural gas), during which fluids can be pressurized. Moreover, the fluids delivered may have different temperatures, typically ranging from 0 ℃ to 50 ℃.
Due to the popularization and application of novel pipeline laying technologies such as trenchless construction and sand-free laying, higher requirements are provided for the capability of resisting the slow cracking of polyethylene materials possibly induced by defects, scratches and the like. Therefore, the resistance to Slow Crack Growth (SCG) as one of the key indicators of polyethylene pipe materials has become the focus of polyethylene pipe material manufacturers, pipe material manufacturers and gas operators in the research and development and evaluation of high-performance pipe materials.
Meanwhile, due to advances in polyethylene material technology and polymerization processes, polyethylene manufacturers are constantly developing materials with higher performance, driving the increase in the corresponding standard requirements, for example in the ISO4437-2007 edition, the requirement for resistance to Slow Crack Growth (SCG) has increased from 165 hours to 500 hours, which is also a standard for the european PE100+ association to evaluate PE100 pipe materials.
Disclosure of Invention
In order to overcome the disadvantages of the prior art, it is an object of the present invention to provide an ethylene polymer composition having a broad molecular weight distribution, a process for its production and its use. The ethylene polymer composition has simple production method and low cost, the obtained ethylene polymer has very reasonable balance between processability and mechanical property, the molecular weight distribution is wide, the notch test result of the slow crack growth resistance performance of the ethylene polymer composition exceeds 5000 hours, and the ethylene polymer composition can be used for preparing pipes.
The specific scheme of the invention is described as follows.
The present invention provides an ethylene polymer composition having a broad molecular weight distribution, which composition is a multimodal composition with respect to molecular weight distribution and/or comonomer distribution, having a weight average molecular weight of 100000-300000 g/mol, a molecular weight distribution defined by the ratio of weight average molecular weight to number average molecular weight of 8-40; the composition comprises a component A and a component B, wherein the component A is a homopolymer of ethylene or a copolymer of ethylene and one or more alpha-olefins with 4-10 carbon atoms, and the weight average molecular weight of the component A is 5000-50000 g/mol, and the component B is a copolymer of ethylene and one or more alpha-olefins with 4-10 carbon atoms, and the weight average molecular weight of the component B is higher than that of the component A; the content of component A is 40-60 wt% and the content of component B is 60-40 wt% based on the total amount of components A and B.
In the present invention, the weight average molecular weight of the ethylene polymer composition is preferably 150000-280000 g/mol; the molecular weight distribution defined by the ratio of the weight average molecular weight to the number average molecular weight is preferably 15 to 35. The comonomer content of the polymer composition is preferably 0.1 to 3 wt.%, preferably 0.5 to 3 wt.%.
In the present invention, the density of the ethylene polymer composition is from 0.941 to 0.960g/cm3Dynamic viscosity η measured at a frequency of 0.05rad/s2.7>220 kPa.S, shear thinning index SHI2.7/100The range of 55 to 100, under a constant load of 2.8MPa (4.4 MPa in the notched section) and at a temperature of 80 ℃, the PENT test according to ASTM F1473 can exhibit a time to failure of more than 5000h, preferably a time to failure of more than 7000h, more preferably of more than 7500 h.
In the present invention, it is preferable that the content of component A is 45 to 55% by weight and the content of component B is 55 to 45% by weight.
In the invention, the weight average molecular weight of the component A is preferably 8000-50000 g/mol. The weight average molecular weight of component B was 150000-900000 g/mol.
In the present invention, in the case of multimodal ethylene polymer compositions, the density of component A is from 0.950 to 0.990g/cm3(ii) the density of component B is lower than the density of component a; preferably, component A has a density of 0.955 to 0.990g/cm3The density of the component B is 0.900-0.950g/cm3。
In the invention, the component B has a comonomer content of 0.2-6 wt%, and the comonomer content in the component B is higher than that in the component A; preferably, component B has a comonomer content of 2 to 6 wt%, the comonomer content in component B being more than 2 wt% higher than the comonomer content in component A.
In the case of multimodal ethylene polymer compositions, the mixture of ethylene polymer components may be a mechanical blend or an in situ blend, or a mixture of a mechanical blend and an in situ blend, wherein a portion of the components are blended in situ and then mechanically blended with the other components of the composition. In situ blend means that the components are mixed together during the polymerization process of the composition described below. The meaning of the terms in situ blend and mechanical blend is well known in the art.
The composition of the present invention may be further mixed with other components. Such mixtures, i.e. blends, comprise the ethylene polymer composition as defined above as well as the other components as provided herein. The other components may be polymer components and/or additives, such as additives conventionally used in polymers. The choice and amount naturally depends on the end use. In the present invention, the ethylene polymer composition may contain additives and auxiliaries known in the art. It may therefore contain antioxidants and stabilizers, for example Irganox 1010 and Irgaphos 168 it may contain antistatic agents, for example ammonium ethoxide, ethoxylated amides and glycerol monostearate, anti-caking agents, for example talc or silica, slip agents, for example oleamide and erucamide, acid neutralizers, for example calcium stearate and zinc stearate, processing aids, for example fluoroelastomers, and nucleating agents, for example sodium benzoate. Suitable amounts of these additives are generally known in the art. Those skilled in the art will be able to select the appropriate additives and amounts thereof to achieve the desired properties of the composition and the pipe made therefrom.
The invention also provides a production method of the ethylene polymer composition with wide molecular weight distribution, which comprises the following steps:
(1) providing ethylene, hydrogen, a transition metal-containing component, and a trialkylaluminum activator in a first polymerization zone with or without an optional α -olefin comonomer of 4 to 10 carbon atoms, thereby forming component A; the transition metal component comprises a metal of group 4 or 5 of the periodic table system;
(2) providing ethylene, hydrogen, a polymerization catalyst and an alpha-olefin comonomer of 4 to 10 carbon atoms in a second polymerization zone to produce an ethylene polymer component B having a weight average molecular weight higher than the weight average molecular weight of component A;
wherein: the first polymerization zone and the second polymerization zone are connected in series, the polymer formed in the first polymerization zone being present in the second polymerization zone, component A representing 40 to 60% by weight and component B representing 60 to 40% by weight, based on the sum of the weights of components A and B.
The first polymerization zone is a loop reactor and the second polymerization zone is a gas phase reactor.
The invention further provides the use of an ethylene polymer composition having a broad molecular weight distribution for the preparation of polyethylene pipe.
The invention has the beneficial effects that: the preparation method is simple and low in cost, and the prepared ethylene polymer composition has wide molecular weight distribution and can be used for preparing high-density polyethylene pipes after the result of the slow crack growth resistance notch test exceeds 5000 hours.
Detailed Description
The present invention will be described in detail with reference to examples.
Production of the composition
The polymer compositions of the present invention can be produced by any polymerization method known in the art, such as slurry, solution or gas phase polymerization. The polymerization may be a single-stage or multistage polymerization.
The at least bimodal multimodal polymer composition can be produced by blending each of the components or a part of the components in situ during the polymerization process, or by mechanically blending two or more separately produced components in a manner known in the art.
In the present invention, the ethylene polymer composition is a multimodal polymer composition comprising components a and B, component a being an ethylene homo-or copolymer and component B being an ethylene copolymer, each component being produced by polymerising ethylene monomers, and one or more alpha-olefin comonomers, in the presence of a polymerisation catalyst in a single or multi-stage polymerisation process. Preferably, components a and B are produced in a multi-stage process using one or more polymerization reactors, which may be the same or different, such as at least any combination of slurry-slurry, gas-phase-gas-phase or slurry-gas-phase polymerization. Each step may be performed in parallel or sequentially using the same or different polymerization methods. In the sequential progression stage, components a and B can be produced in any order by conducting the polymerization in each step other than the first step, in the presence of the polymer component formed in the preceding step. Preferably, the catalyst used in the preceding step is also present in the subsequent polymerization step. Alternatively, a further catalyst (which may be the same or different from the catalyst used in the previous step) may be added in a subsequent step.
The catalyst is not critical, however, a Ziegler-Natta polymerization catalyst is preferably used. The catalyst includes a transition metal component and an activator.
Particularly preferred transition metal components include titanium halides, alkoxyalkyl magnesium compounds, and alkyl aluminum dihalides supported on inorganic oxide supports.
The activator is a compound capable of activating the transition metal component. Useful activators are especially aluminum alkyls and aluminum alkoxide compounds. Particularly preferred activators are aluminum alkyls, especially trialkylaluminums, such as trimethylaluminum, triethylaluminum and triisobutylaluminum.
Production of component A (Low molecular weight polymerization stage)
In the production of component A (low molecular weight polymerization stage), ethylene is homopolymerized or copolymerized with one or more alpha-olefin comonomers of 4 to 10 carbon atoms. The polymerization can occur in slurry, solution or gas phase.
The temperature within the polymerization reactor needs to be high enough to achieve an acceptable activity of the catalyst. On the other hand, the temperature should not exceed the softening temperature of the polymer. The temperature may be selected in the range of 50-110 deg.C, preferably 75-105 deg.C and more preferably 75-100 deg.C.
The pressure in the reactor can be selected to meet the desired objectives: to achieve the desired density of the reaction medium, to achieve the appropriate monomer concentration or to maintain the reactants in the reactor in the liquid phase. In slurry polymerization, suitable pressures are in the range of from 10 to 100bar, preferably from 30 to 80 bar. In the gas-phase polymerization, the pressure is from 5 to 50bar, preferably from 10 to 30 bar.
If component a is produced in a slurry, ethylene and an inert liquid diluent are introduced into the reactor along with the polymerization catalyst. Hydrogen is introduced into the reactor to control the weight average molecular weight of the polymer. In addition, comonomers can be used to control the density of the polymer. The exact amount of hydrogen and final comonomer addition is set by the type of catalyst used and the target weight average molecular weight and density. Suitably, the hydrogen to ethylene ratio in the feed stream phase is in the range of from 50 to 600mol/kmol and the comonomer to ethylene ratio is in the range of from 0 to 100mol/kmol, preferably from 0 to 50 mol/kmol. If the polymerization is carried out as a slurry polymerization, any suitable reactor type known in the art may be used. Continuous stirred tank reactors and loop reactors are examples of useful reactor type combinations. In particular, a loop reactor is preferred, since it is particularly advantageous to carry out the polymerization under so-called supercritical conditions above the critical temperature and pressure of the fluid.
Production of component B (high molecular weight polymerization stage)
In the production of component B (high molecular weight polymerization stage), ethylene is copolymerized together with one or more alpha-olefin comonomers having from 4 to 10 carbon atoms. The polymerization can occur in slurry, solution or gas phase.
The temperature within the polymerization reactor needs to be high enough to achieve an acceptable activity of the catalyst. On the other hand, the temperature should not exceed the softening temperature of the polymer. The temperature may be selected in the range of 50-110 deg.C, preferably 75-105 deg.C and more preferably 75-100 deg.C.
The pressure in the reactor can be selected to meet the desired objectives: to achieve the desired density of the reaction medium, to achieve the appropriate monomer concentration or to maintain the reactants in the reactor in the liquid phase. In slurry polymerization, suitable pressures are in the range of from 10 to 100bar, preferably from 30 to 80 bar. In the gas-phase polymerization, the pressure is from 5 to 50bar, preferably from 10 to 30 bar.
If the high molecular weight component B is produced in a gas phase reactor. In this case, a gas-phase fluid comprising monomer, inert gas, hydrogen and optionally comonomer is introduced into the reactor, where the polymerization takes place. Typically, the ratio of hydrogen to ethylene in the gas phase fluid is from 10 to 100mol/kmol and the ratio of comonomer to ethylene is from 10 to 200 mol/kmol.
The process for producing the above polymer composition therefore preferably comprises the step of polymerising ethylene monomer, optionally together with one or more comonomers, preferably alpha-olefin comonomer, in a slurry reactor, preferably a loop reactor, in the presence of a polymerisation catalyst to produce component a.
And optionally transferring the reaction product of the above step to a subsequent gas phase reactor.
In a gas phase reactor, polymerizing ethylene monomer, optionally one or more alpha-olefin comonomers, in the presence of the reaction product of the above step, producing component B to obtain the polymer composition of the present invention.
Use of a composition
The composition can be used to produce different types of articles. Particularly useful compositions are for making pipes, especially large bore gas pipes. The composition can be processed into large bore pipe with good sag resistance and high flow through. The obtained pipe has super-strong resistance to chronic crack growth, can be used for a long time, and has no defect and safety risk.
Description of the analytical methods
The weight average Molecular Weight (MW) and Molecular Weight Distribution (MWD) of the polyethylene product were determined on an AllianceGPC model 2000 Gel Permeation Chromatograph (GPC) instrument from Waters, USA, with a test temperature of 150 ℃, polystyrene as a standard, trichlorobenzene as a solvent, and a flow rate of 1.0 ml/min.
Melt flow index MFR2: the melt flow index MFR is determined according to ISO method 1133, measured at 190 ℃ under 2.16kg (corresponding to ASTM D1238, condition L).
Alpha-olefin content: the comonomer content is tested by adopting an infrared-nuclear magnetic resonance combined method, adopting a nuclear magnetic resonance method to determine a standard curve, adopting an IFS 66/S type infrared spectrum analyzer of Bruker Germany to test the infrared absorption spectrum of the polyethylene film according to GB/T6040-2002, and obtaining the comonomer content through the standard curve.
Density: the bulk density of the polymer product was tested according to ISO 1183 standard using a BHM-2 type density gradient column.
Dynamic viscosity and shear thinning index: dynamic rheology measurements were performed on compression moulded samples using a 25mm diameter plaque and a plaque with a 1.2mm gap under nitrogen atmosphere at 190 ℃ using a rheometer. Oscillatory shear experiments (ISO 67211) were carried out at frequencies of 0.05 to 300rad/s, in the range of strained linear viscosities.
Single notch creep test: the failure time of the polyethylene material was obtained by performing experiments according to ASTM F1473 on a self-made instrument set-up using compression molded samples under a constant load of 2.8MPa (gap segment of 4.4MPa) and at a temperature of 80 ℃.
Example 1
Propane, ethylene and hydrogen were introduced continuously in a loop reactor having a volume of 250 liters. In addition, a silica-supported titanium magnesium catalyst was introduced into the reactor along with a triethylaluminum apparatus, the molar ratio of aluminum in the activator to titanium in the solid component being 20. The loop reactor was operated at a temperature of 95 ℃ and a pressure of 55 bar. In the loop reactor the ethylene content in the fluid phase was 1.8 mol% and the hydrogen to ethylene ratio was 480 mol/kmol. The production rate of the polymer was 14.5 kg/h. The weight average molecular weight of the polymer produced in the loop reactor was 21771g/mol, the molecular weight distribution was 4.55, and the density was 0.979g/cm3。
The slurry was withdrawn from the loop reactor to a flash vessel where the pressure was reduced to 3 bar. The polymer was then directed to a fluidized bed gas phase reactor where additional ethylene, 1-hexene comonomer and hydrogen were also added as well as propane, nitrogen as inert gas. The gas phase reactor was operated at a temperature of 85 ℃ and a pressure of 20 bar. In the reactor, the ethylene partial pressure in the recycle gas was 1bar, the hydrogen to ethylene ratio was 20mol/kmol, and the 1-hexene to ethylene ratio was 35 mol/kmol. The production rate of the polymer in the gas phase reactor was 15.5kg/h so that the production ratio between the loop and the gas phase reactor was 48/52. The total production rate was 30 kg/h.
The final density of the polymer mass is 0.948 g-cm3Weight average molecular weight of 241346 and molecular weight distribution of 27 dynamic viscosity of η2.7Is 300 kPa.S and shear thinning index SHI2.7/210Is 80. The 1-hexene content in the polymer was 1.7% by weight. The failure time of the chronic crack resistance test is 5500 h.
Example 2
Propane, ethylene and hydrogen were introduced continuously in a loop reactor having a volume of 250 liters. In addition, a silica-supported titanium magnesium catalyst was introduced into the reactor along with a triethylaluminum apparatus, the molar ratio of aluminum in the activator to titanium in the solid component being 20. The loop reactor was operated at a temperature of 95 ℃ and a pressure of 55 bar. In the loop reactor the ethylene content in the fluid phase was 1.8 mol%, the ratio of hydrogen to ethylene was 480mol/kmol and the ratio of 1-hexene to ethylene was 5 mol/kmol. The production rate of the polymer was 13.8 kg/h. The weight average molecular weight of the polymer produced in the loop reactor was 23512g/mol, the molecular weight distribution was 4.64, and the density was 0.977g/cm3。
The slurry was withdrawn from the loop reactor to a flash vessel where the pressure was reduced to 3 bar. The polymer was then directed to a fluidized bed gas phase reactor where additional ethylene, 1-hexene comonomer and hydrogen were also added as well as propane, nitrogen as inert gas. The gas phase reactor was operated at a temperature of 85 ℃ and a pressure of 20 bar. In the reactor, the ethylene partial pressure in the recycle gas was 1bar, the hydrogen to ethylene ratio was 20mol/kmol, and the 1-hexene to ethylene ratio was 40 mol/kmol. The production rate of polymer in the gas phase reactor was 16.2kg/h so that the production ratio between the loop and the gas phase reactor was 46/54. The total production rate was 30 kg/h.
The final density of the polymer mass was 0.946g/cm3Weight average molecular weight of 256374 and molecular weight distribution of 29. dynamic viscosity of η2.7Is 320kPa · S and shear thinning index SHI2.7/210Is 85. The 1-hexene content in the polymer was 1.9% by weight. The failure time of the chronic crack resistance test is 5800 h.
Comparative example 1
The commercially available ethylene polymer compositions were analyzed for their resistance to chronic crack growth and a time to failure of 215 h.
Comparative example 2
Another commercially available ethylene polymer composition was analyzed for its resistance to chronic crack growth with a time to failure of 500 h.
Claims (2)
1. An ethylene polymer composition having a broad molecular weight distribution, characterized by: the composition is prepared by the following method, comprising the following steps: continuously introducing propane, ethylene and hydrogen into a loop reactor having a volume of 250 liters; additionally, a silica-supported titanium magnesium catalyst was introduced into the reactor along with triethylaluminum, the molar ratio of aluminum in the activator to titanium in the solid component being 20; operating the loop reactor at a temperature of 95 ℃ and a pressure of 55 bar; in the loop reactor, the ethylene content in the fluid phase was 1.8 mol%, the ratio of hydrogen to ethylene was 480 mol/kmol; the production rate of the polymer was 14.5 kg/h; the weight average molecular weight of the polymer produced in the loop reactor was 21771g/mol, the molecular weight distribution was 4.55, and the density was 0.979g/cm3；
Withdrawing slurry from the loop reactor to a flash vessel where the pressure is reduced to 3 bar; the polymer is then conducted to a fluidised bed gas phase reactor where additional ethylene, 1-hexene comonomer and hydrogen are added as well as propane and nitrogen as inert gases; the gas phase reactor was operated at a temperature of 85 ℃ and a pressure of 20 bar; in the reactor, the ethylene partial pressure in the recycle gas was 1bar, the ratio of hydrogen to ethylene was 20mol/kmol, and the ratio of 1-hexene to ethylene was 35 mol/kmol; the production rate of the polymer in the gas phase reactor was 15.5kg/h so that the production ratio between the loop and the gas phase reactor was 48/52. The total production speed is 30 kg/h;
the final density of the polymer mass was 0.948g/cm3Weight average molecular weight of 241346, molecular weight distribution of 27, dynamic viscosity of η2.7Is 300 kPa.S and shear thinning index SHI2.7/210Is 80; the 1-hexene content in the polymer was 1.7 wt%; the failure time of the chronic crack resistance test is 5500 h.
2. Ethylene with wide molecular weight distributionA polymer composition characterized by: the composition is prepared by the following method, comprising the following steps: continuously introducing 1-hexene, propane, ethylene and hydrogen into a loop reactor with a volume of 250 liters; in addition, a silica-supported titanium magnesium catalyst was introduced into the reactor along with triethylaluminum, with a molar ratio of aluminum in the activator to titanium in the solid component of 20. Operating the loop reactor at a temperature of 95 ℃ and a pressure of 55 bar; in the loop reactor, the ethylene content in the fluid phase was 1.8 mol%, the ratio of hydrogen to ethylene was 480mol/kmol, and the ratio of 1-hexene to ethylene was 5 mol/kmol; the production rate of the polymer was 13.8 kg/h; the weight average molecular weight of the polymer produced in the loop reactor was 23512g/mol, the molecular weight distribution was 4.64, and the density was 0.977g/cm3；
The slurry was withdrawn from the loop reactor to a flash vessel where the pressure was reduced to 3 bar. The polymer is then conducted to a fluidised bed gas phase reactor where additional ethylene, 1-hexene comonomer and hydrogen are added as well as propane and nitrogen as inert gases; the gas phase reactor was operated at a temperature of 85 ℃ and a pressure of 20 bar; in the reactor, the ethylene partial pressure in the recycle gas was 1bar, the hydrogen to ethylene ratio was 20mol/kmol, and the 1-hexene to ethylene ratio was 40 mol/kmol; the production rate of polymer in the gas phase reactor was 16.2kg/h so that the production ratio between the loop and the gas phase reactor was 46/54. The total production speed is 30 kg/h;
the final density of the polymer mass was 0.946g/cm3Weight average molecular weight of 256374, molecular weight distribution of 29, dynamic viscosity of η2.7Is 320kPa · S and shear thinning index SHI2.7/210Is 85; the 1-hexene content in the polymer was 1.9 wt%, and the failure time in the chronic crack resistance test was 5800 h.
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| CN101903479B (en) * | 2007-12-20 | 2014-05-21 | 北方科技有限公司 | Process for coating a pipe with high throughput using multimodal ethylene copolymer, and coated pipes obtained thereof |
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