CN115340619B - Low ash content ultra-high molecular weight polyethylene resin and preparation method thereof - Google Patents
Low ash content ultra-high molecular weight polyethylene resin and preparation method thereof Download PDFInfo
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- CN115340619B CN115340619B CN202110519165.XA CN202110519165A CN115340619B CN 115340619 B CN115340619 B CN 115340619B CN 202110519165 A CN202110519165 A CN 202110519165A CN 115340619 B CN115340619 B CN 115340619B
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- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 title claims abstract description 88
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 title claims abstract description 85
- 239000011347 resin Substances 0.000 title claims abstract description 57
- 229920005989 resin Polymers 0.000 title claims abstract description 57
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 238000006116 polymerization reaction Methods 0.000 claims description 78
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 42
- 239000005977 Ethylene Substances 0.000 claims description 42
- 239000003054 catalyst Substances 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 26
- 239000004711 α-olefin Substances 0.000 claims description 20
- 239000002904 solvent Substances 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 16
- 229920000642 polymer Polymers 0.000 claims description 13
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 claims description 6
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 claims description 6
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 6
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 claims description 6
- 238000001704 evaporation Methods 0.000 claims description 5
- 230000008020 evaporation Effects 0.000 claims description 5
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 5
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 5
- 239000011954 Ziegler–Natta catalyst Substances 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 4
- TVMXDCGIABBOFY-UHFFFAOYSA-N n-Octanol Natural products CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- MCULRUJILOGHCJ-UHFFFAOYSA-N triisobutylaluminium Chemical compound CC(C)C[Al](CC(C)C)CC(C)C MCULRUJILOGHCJ-UHFFFAOYSA-N 0.000 claims description 4
- VOITXYVAKOUIBA-UHFFFAOYSA-N triethylaluminium Chemical group CC[Al](CC)CC VOITXYVAKOUIBA-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims 1
- 238000009987 spinning Methods 0.000 abstract description 28
- 239000000835 fiber Substances 0.000 abstract description 23
- 230000002035 prolonged effect Effects 0.000 abstract description 4
- 239000012535 impurity Substances 0.000 abstract description 3
- 239000002184 metal Substances 0.000 abstract description 3
- 229910052751 metal Inorganic materials 0.000 abstract description 3
- 239000000203 mixture Substances 0.000 abstract description 2
- 238000006243 chemical reaction Methods 0.000 description 55
- 239000000843 powder Substances 0.000 description 21
- 230000008569 process Effects 0.000 description 16
- 239000004698 Polyethylene Substances 0.000 description 10
- -1 polyethylene Polymers 0.000 description 10
- 229920000573 polyethylene Polymers 0.000 description 10
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000000499 gel Substances 0.000 description 3
- 238000001891 gel spinning Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 125000005234 alkyl aluminium group Chemical group 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000037048 polymerization activity Effects 0.000 description 2
- 230000004224 protection Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 230000006750 UV protection Effects 0.000 description 1
- 229920010741 Ultra High Molecular Weight Polyethylene (UHMWPE) Polymers 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010035 extrusion spinning Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229920001903 high density polyethylene Polymers 0.000 description 1
- 229920006253 high performance fiber Polymers 0.000 description 1
- 239000004700 high-density polyethylene Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000011240 wet gel Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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- 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
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- 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
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F6/30—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising olefins as the major constituent
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
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Abstract
The application provides a low ash content ultra-high molecular weight polyethylene resin and a preparation method thereof. The ash content in the low ash content ultra-high molecular weight polyethylene resin is less than or equal to 80ppm, and the viscosity average molecular weight is 500-800 ten thousand. The ultra-high molecular weight polyethylene provided by the application has the advantages of uniform composition, high viscosity average molecular weight of 500-800 ten thousand, low ash content, low metal impurity content and the like. Therefore, when the fiber is used for spinning and the like, the uniformity of the yarn can be improved, the service life of a spinning process device is prolonged, and the strength and the service performance of a spinning product are improved.
Description
Technical Field
The application relates to synthesis of ultra-high molecular weight polyethylene resin, in particular to low ash ultra-high molecular weight polyethylene resin and a preparation method thereof.
Background
Ultra-high molecular weight polyethylene fibers (Ultra High Molecular Weight Polyethylene Fiber), also known as high-strength high-modulus polyethylene fibers, also known as extended chain polyethylene fibers (ECPE), are the third generation high performance fibers that were originally present in the early 90 s of the 20 th century, and the raw material is ultra-high molecular weight linear polyethylene. The ultra-high molecular weight linear polyethylene is the fiber with highest specific strength and specific modulus in the world at present, the molecular shape is a linear straightening chain structure, and the orientation degree is close to 100%; the fiber product has the characteristics of high strength, high modulus, high orientation degree, corrosion resistance, ultraviolet resistance, difficult abrasion, outstanding impact resistance, cutting resistance, toughness and the like, and is widely applied to special rope belts, fishing nets, sports equipment, various light soft bulletproof clothes, bulletproof helmets, riot shields, explosion-proof devices and other protective products.
There are two main routes of current UHMWPE fibers for industrial production: a high-volatility solvent dry gel spinning process route and a low-volatility solvent wet gel spinning process route.
The prior document (chinese patent No. cn2008011010402. X) provides a process that involves producing gel-spun ultra-high molecular weight polyethylene (UHMWPE) fibers with high tensile strength and improved creep rate, such gel-spun UHMWPE fibers being suitable for use in a variety of applications, such as ropes, medical devices, composite articles and ballistic resistant articles, which process focuses on gel spinning of ultra-high molecular weight polyethylene fibers, rather than on ultra-high molecular weight polyethylene fiber grade resins.
The prior document (Chinese patent CN 201010023179.4) provides a preparation method of high-strength high-modulus polyethylene fiber, which comprises the steps of mixing ultra-high molecular weight polyethylene powder with the molecular weight of 150-800 ten thousand with a solvent according to the mass ratio of 1-10:100, heating and stirring in a mixing kettle to fully dissolve the powder to obtain ultra-high molecular weight polyethylene solution, and naturally cooling to form gel blocks; taking out the gel block, crushing the gel block into granules, removing part of solvent to obtain an ultra-high molecular weight polyethylene spinning raw material with the solid content of 20-70 wt%, and inputting the prepared ultra-high molecular weight polyethylene spinning raw material into a screw for melt extrusion spinning to obtain the high-strength high-modulus polyethylene fiber. The patent mainly utilizes a method of blending an auxiliary agent to prepare fiber resin.
Ash is the sum of the content of the ultra-high molecular weight polyethylene fibers and the content of inorganic compounds such as nonflammable metals in the catalyst. Higher ash content means that the purity of the resin is lower, the melt can be broken in the spinning process when the cleanliness is poor and the ash content is too high, the resistance is large when the melt is filtered by the component, the pressure is uneven, the uniformity of yarn outlet is affected, the service life of the filter is shortened, the spinneret plate is easy to block, instant material dripping in the spinning process is caused to lead to yarn winding, and the strength of a spinning product and the service performance of the product are reduced. Therefore, in the spinning industry, the ash index of UHMWPE resin is highly required, and the ash index is desirably controlled below 100 PPm. No preparation method of ultra-high molecular weight polyethylene powder and how to reduce ash content in the base material are proposed in the prior literature. In view of the above, there is a need to provide a method capable of reducing ash in ultra high molecular weight polyethylene fibers.
Disclosure of Invention
The application mainly aims to provide a low-ash ultrahigh molecular weight polyethylene resin and a preparation method thereof, so as to solve the problem that the low-ash ultrahigh molecular weight polyethylene resin prepared by the existing method has higher ash content.
In order to achieve the above purpose, the application provides a low ash content ultra-high molecular weight polyethylene resin, wherein the ash content in the low ash content ultra-high molecular weight polyethylene resin is less than or equal to 80ppm, and the viscosity average molecular weight is 500-800 ten thousand.
Further, the particle diameter of the low ash ultra-high molecular weight polyethylene resin is 100-350 mu m, and the bulk density is 0.40-0.50 g/cm 3 。
The application also provides a preparation method of the low ash content ultra-high molecular weight polyethylene resin, which comprises the following steps: step S1, dividing ethylene into two parts, and carrying out a first polymerization reaction on the first part of ethylene in the presence of inert atmosphere, a main catalyst and a cocatalyst to obtain a first product system containing a first polymer, wherein the temperature of the first polymerization reaction is 50-60 ℃, the pressure is 0.3-0.6 MPa, the polymerization time is 1-2 h, and the addition amount of the ethylene in the step S1 is 20-50% of the total addition amount of the ethylene; and S2, carrying out a second polymerization reaction on the first product system and the rest of ethylene to obtain the low ash content ultra-high molecular weight polyethylene resin, wherein the temperature of the second polymerization reaction is 60-85 ℃, the pressure is 0.6-1.0 MPa, and the polymerization time is 0.5-2 h.
Further, the preparation method of the low ash ultra-high molecular weight polyethylene resin comprises the following steps: in the step S1, monitoring the molecular weight of the first polymer, and obtaining a first product system when the viscosity average molecular weight of the first polymer is 200-400 ten thousand; and monitoring a product system of the second polymerization reaction in the step S2, and obtaining the low ash ultrahigh molecular weight polyethylene resin when the viscosity average molecular weight of the product system of the second polymerization reaction is 500-800 ten thousand.
Further, an alpha-olefin is added during the second polymerization reaction; preferably, the alpha-olefin is selected from one or more of the group consisting of propylene, 1-butene, 1-pentene, 1-hexene and 1-octene.
Further, the alpha-olefin is used in an amount of not more than 2%, more preferably not more than 1%, by volume of the first product system.
Further, the temperature of the first polymerization reaction is 50-55 ℃ and the pressure is 0.3-0.5 MPa; the temperature of the second polymerization reaction is 75-85 ℃ and the pressure is 0.6-1.0 MPa.
Further, a solvent is added during both the first polymerization process and the second polymerization process.
Further, the main catalyst is a Ziegler Natta catalyst, preferably a catalyst of the Mg-Ti system; the cocatalyst is an alkylaluminum, preferably triethylaluminum and/or triisobutylaluminum.
Further, the preparation method of the low ash ultra-high molecular weight polyethylene resin comprises the following steps: the product system of the second polymerization reaction is subjected to flash evaporation and centrifugal drying in sequence.
Compared with the prior art which only comprises one polymerization reaction, the preparation method provided by the application comprises two continuous polymerization reactions, and only the main catalyst and the cocatalyst are added in the first polymerization reaction, so that the residence time of the catalyst can be greatly prolonged, the catalytic efficiency of the catalyst can be fully exerted, and the polymerization activity of the unit catalyst can be improved, therefore, the consumption of the catalyst and the cocatalyst can be reduced in the whole process, and the ultrahigh molecular weight polyethylene resin with lower ash content can be correspondingly prepared. Meanwhile, the molecular weight and toughness of the polyethylene can be greatly improved by limiting the reaction temperature, pressure and polymerization time of the first polymerization process and the second polymerization process and the use amount of ethylene in each step within the above ranges and adding alpha-olefin in the second polymerization process. In summary, by improving the existing technology and combining with the adjustment of the addition amount of ethylene, the polyethylene fiber with ultra-high molecular weight and high toughness is obtained, and the ash content is greatly reduced.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The present application will be described in detail with reference to examples.
As described in the background art, the low ash content ultra-high molecular weight polyethylene resin prepared by the prior method has the problem of high ash content and easy generation. In order to solve the technical problems, the application provides the low-ash ultrahigh molecular weight polyethylene resin, wherein the ash content in the low-ash ultrahigh molecular weight polyethylene resin is less than or equal to 80ppm, and the viscosity average molecular weight is 500-800 ten thousand.
The ultra-high molecular weight polyethylene provided by the application has the advantages of uniform composition, high viscosity average molecular weight of 500-800 ten thousand, low ash content, low metal impurity content and the like. Therefore, when the fiber is used for spinning and the like, the uniformity of the yarn can be improved, the service life of a spinning process device is prolonged, and the strength and the service performance of a spinning product are improved.
In order to further improve the overall properties of the spun article formed therefrom, it is preferable that the low ash ultra high molecular weight polyethylene resin is formed into pellets having a particle diameter of 100 to 350 μm and a bulk density of 0.40 to 0.50g/cm 3 。
The application also provides a preparation method of the low ash content ultra-high molecular weight polyethylene resin, which comprises the following steps: step S1, dividing ethylene into two parts, and carrying out a first polymerization reaction on the first part of ethylene in the presence of inert atmosphere, a main catalyst and a cocatalyst to obtain a first product system containing a first polymer, wherein the temperature of the first polymerization reaction is 50-60 ℃, the pressure is 0.3-0.6 MPa, the polymerization time is 1-2 h, and the addition amount of the ethylene in the step S1 is 20-50% of the total addition amount of the ethylene; and S2, carrying out a second polymerization reaction on the first product system and the rest of ethylene to obtain the low ash content ultra-high molecular weight polyethylene resin, wherein the temperature of the second polymerization reaction is 60-85 ℃, the pressure is 0.6-1.0 MPa, and the polymerization time is 0.5-2 h.
In the polymerization reaction process, ethylene is initially polymerized to form an ethylene prepolymer with low molecular weight in the first polymerization reaction process; then, in the second polymerization process, the ethylene prepolymer, ethylene and alpha-olefin are further polymerized to obtain an ultra-high molecular weight polyethylene resin.
Compared with the prior art which only comprises one polymerization reaction, the preparation method provided by the application comprises two continuous polymerization reactions, and the main catalyst and the cocatalyst are only added into the first polymerization reaction, so that the residence time of the catalyst can be greatly prolonged, the catalytic efficiency of the catalyst can be fully exerted, and the polymerization activity of the unit catalyst can be improved, therefore, the consumption of the catalyst and the cocatalyst can be reduced in the whole process, and the ultrahigh molecular weight polyethylene resin with lower ash content can be correspondingly prepared. Meanwhile, the molecular weight and toughness of the polyethylene can be greatly improved by limiting the reaction temperature, pressure and polymerization time of the first polymerization process and the second polymerization process and the amount of ethylene used in each step in the above ranges. In summary, by improving the existing technology and combining with the adjustment of the addition amount of ethylene, the polyethylene fiber with ultra-high molecular weight and high toughness is obtained, and the ash content is greatly reduced.
Optionally, the ethylene is added in an amount of 20%, 25%, 30%, 33.3%, 40%, 42.8%, 50% of the total amount of ethylene added in step S1.
Since the existing ultra-high molecular weight polyethylene resin is generally in the form of powder. In a preferred embodiment, the method of preparing the low ash ultra high molecular weight polyethylene resin comprises: in the step S1, monitoring the molecular weight of the first polymer, and obtaining a first product system when the viscosity average molecular weight of the first polymer is 200-400 ten thousand; and monitoring a product system of the second polymerization reaction in the step S2, and obtaining the low ash ultrahigh molecular weight polyethylene resin when the viscosity average molecular weight of the product system of the second polymerization reaction is 500-800 ten thousand. The content of the reactive oligomer of the second polymerization reaction can be greatly increased by defining the viscosity average molecular weight of the first polymerization product in the first polymerization reaction, so that the molecular weight of polyethylene can be further increased while reducing the particle size and bulk density of the ultra-high molecular weight polyethylene resin powder. Preferably, the first polymerization and the second polymerization are slurry polymerization processes, which may be carried out in a series of reaction vessels.
In a preferred embodiment, an alpha-olefin is also added during the second polymerization reaction. The addition of alpha-olefins is advantageous for further increasing the flexibility of the ultra-high molecular weight. Preferably, the above alpha-olefin is selected from one or more of the group consisting of propylene, 1-butene, 1-pentene, 1-hexene and 1-octene.
More preferably, the amount of alpha-olefin used during the second polymerization reaction is not more than 2%, more preferably not more than 1% by volume of the first product system.
In a preferred embodiment, the temperature of the first polymerization reaction is 50 to 55℃and the pressure is 0.3 to 0.5MPa; the temperature of the second polymerization reaction is 75-85 ℃ and the pressure is 0.6-1.0 MPa. Compared with other temperature and pressure ranges, the temperature and pressure of the first polymerization reaction and the second polymerization reaction are limited to the above ranges, which is favorable for further improving the reactivity of the catalyst and the cocatalyst, thereby being favorable for further improving the yield of the ultra-high molecular weight polyethylene resin.
In order to make the reaction raw materials more uniformly mixed while removing the reaction heat of the reaction process, a solvent is also added to the first polymerization process and the second polymerization process. Preferably, the solvent includes, but is not limited to, one or more of the group consisting of hexane, heptane, octane and decane. Compared with other solvents, the solvents have higher specific heat capacity, so that heat generated in the reaction process can be well removed, the generation risk of side reactions can be reduced, and the uniformity of molecular weight in polyethylene can be improved.
Preferably, during the first polymerization, the ethylene feed is 50 to 150kg/h; in the second polymerization process, the ethylene feeding amount is 200-650 kg/h.
In a preferred embodiment, the procatalyst is a ziegler natta catalyst, more preferably a Mg-Ti system catalyst (preferably prepared by the preparation method of chinese patent application 201610248520.3); the cocatalyst is an alkylaluminum, more preferably triethylaluminum and/or triisobutylaluminum.
In order to further reduce the impurities in the ultra-high molecular weight polyethylene product obtained in accordance with the present application, the product system of the second polymerization reaction is preferably subjected to flash evaporation and centrifugal drying in sequence.
The low ash ultra high molecular weight polyethylene resin can be used for fiber spinning.
The application is described in further detail below in connection with specific examples which are not to be construed as limiting the scope of the application as claimed.
Example 1
The preparation method of the low ash content ultra-high molecular weight polyethylene fiber-grade resin provided by the application comprises the following steps: at 20m 3 And (3) sequentially adding 6.5KG/h of triisobutylaluminum as a cocatalyst and 3KG/h of a supported Mg-Ti Ziegler-Natta catalyst into a hexane solvent, and stirring and mixing for 2 hours under the protection of nitrogen so as to uniformly disperse the catalyst in the solvent and obtain a catalyst dispersion liquid. The preparation method of the catalyst is shown in Chinese patent application 201610248520.3, example 1.
The catalyst dispersion liquid and fresh ethylene are continuously added into a first reaction kettle of a Hoechst high-density polyethylene process device connected in series through a metering pump for slurry polymerization, and the average residence time of materials in the reaction kettle is 1 hour, so that a first product system of a first polymerization product is obtained.
The first product system (150 kg/h) is subjected to flash evaporation to remove volatile components, and then enters a second reaction kettle (hexane solvent is added through a metering pump, the addition amount is two thirds of the volume of the polymerization kettle), ethylene and comonomer propylene are continuously introduced, no new catalyst is added into the second reaction kettle, and the average retention time of materials is 1.5 hours, so that a second product system is obtained; and carrying out flash evaporation, solid-liquid separation and drying on the second product system to obtain the low ash content ultra-high molecular weight polyethylene fiber level resin powder, which is marked as UHMWPE-1.
The specific production process control parameters of the reaction kettle are shown in table 1.
TABLE 1
| Process parameters | First reaction kettle | Second reaction kettle |
| Ethylene feed (kg/h) | 100 | 300 |
| Alpha-olefin (propylene) feed (kg/h) | 0 | 3 |
| Solvent (kg/h) | 200 | 200 |
| Still temperature (DEG C) | 50 | 60 |
| Cauldron pressure (MPa) | 0.3 | 0.6 |
| Viscosity average molecular weight of the first Polymer | 232 | \ |
Example 2
Substantially the same as in example 1, but with the following changes in the process parameters:
the ethylene feeding amount of the second reaction kettle is changed to 400kg/h;
the alpha-olefin feeding amount of the second reaction kettle is changed to 0;
the kettle temperatures of the first reaction kettle and the second reaction kettle are respectively controlled at 52 ℃ and 80 ℃.
The specific production process control parameters of the reaction kettle are shown in Table 2. The ultra-high molecular weight polyethylene powder for spinning was designated UHMWPE-2, and the test results are shown in Table 7.
TABLE 2
Example 3
Substantially the same as in example 1, but with the following changes in the process parameters:
the ethylene feeding amount of the second reaction kettle is changed to 500kg/h;
the kettle temperatures of the first reaction kettle and the second reaction kettle are respectively controlled at 53 ℃ and 75 ℃, and the addition amount of the solvent in the first reaction kettle and the second reaction kettle is respectively 150 and 200kg/h.
The specific production process control parameters of the reaction kettle are shown in Table 3. The ultra-high molecular weight polyethylene powder for spinning was designated UHMWPE-3 and the test results are shown in Table 7.
TABLE 3 Table 3
| Process parameters | First reaction kettle | Second reaction kettle |
| Ethylene feed (kg/h) | 130 | 500 |
| Alpha-olefin feed (kg/h) | 0 | 3 |
| Solvent (kg/h) | 150 | 200 |
| Still temperature (DEG C) | 53 | 75 |
| Cauldron pressure (MPa) | 0.4 | 0.9 |
| Viscosity average molecular weight of the first Polymer | 272 | \ |
Example 4
Substantially the same as in example 1, but with the following changes in the process parameters:
the ethylene feeding amount of the second reaction kettle is changed to 600kg/h;
the kettle temperatures of the first reaction kettle and the second reaction kettle are respectively controlled at 60 ℃ and 75 ℃, the addition amount of the solvent in the first reaction kettle and the second reaction kettle is respectively 300kg/h, and the kettle pressures of the first reaction kettle and the second reaction kettle are respectively 0.6MPa and 0.8MPa.
The specific production process control parameters of the reaction kettle are shown in Table 4. The ultra-high molecular weight polyethylene powder for spinning was designated UHMWPE-4 and the test results are shown in Table 7.
TABLE 4 Table 4
Example 5
Substantially the same as in example 1, but with the following changes in the process parameters:
the ethylene feeding amount of the first reaction kettle and the second reaction kettle is changed into 200kg/h and 400kg/h respectively;
the alpha-olefin feeding amount of the second reaction kettle is changed to 0;
the kettle temperatures of the first reaction kettle and the second reaction kettle are respectively controlled at 55 ℃ and 76 ℃, the addition amount of the solvent in the first reaction kettle and the second reaction kettle is respectively 300kg/h, and the kettle pressures of the first reaction kettle and the second reaction kettle are respectively 0.4MPa and 0.9MPa.
The specific production process control parameters of the reaction kettle are shown in Table 5. The ultra-high molecular weight polyethylene powder for spinning was designated UHMWPE-5 and the test results are shown in Table 7.
TABLE 5
Example 6
Substantially the same as in example 1, but with the following changes in the process parameters:
the ethylene feeding amount of the first reaction kettle and the second reaction kettle is respectively changed into 300kg/h and 400kg/h;
the alpha-olefin feeding amount of the second reaction kettle is changed to 0;
the temperature of the first reaction kettle and the second reaction kettle are respectively controlled at 50 ℃ and 75 ℃, and the kettle pressures of the first reaction kettle and the second reaction kettle are respectively 0.3MPa and 0.8MPa.
The specific production process control parameters of the reaction kettle are shown in Table 6, the prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-6, and the test results are shown in Table 7.
TABLE 6
Example 7
The differences from example 1 are: alpha-olefin is not added into the first reaction kettle and the second reaction kettle.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-7.
Example 8
The differences from example 1 are: the amount of alpha-olefin added was 4%.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-8.
Example 9
The differences from example 1 are: the first polymer had a viscosity average molecular weight of 500 ten thousand.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-9.
Example 10
The differences from example 1 are: the first polymer has a viscosity average molecular weight of 100 ten thousand.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-10.
Example 11
The differences from example 1 are: the amount of ethylene added in step S1 was 50% of the total amount of ethylene added.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-11.
Comparative example 1
The differences from example 1 are: the amount of ethylene added in step S1 was 10% of the total amount of ethylene added.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-12.
Comparative example 2
The differences from example 1 are: the amount of ethylene added in step S1 was 60% of the total amount of ethylene added.
The obtained ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-13.
Comparative example 3
The differences from example 1 are: the temperature of the first polymerization reaction is 40 ℃ and the pressure is 0.6MPa; the second polymerization reaction was carried out at a temperature of 90℃and a pressure of 1.4MPa.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-14.
Comparative example 4
The differences from example 1 are: the temperature of the first polymerization reaction is 60 ℃ and the pressure is 0.1MPa; the second polymerization reaction was carried out at a temperature of 70℃and a pressure of 0.4MPa.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-15.
Comparative example 5
The differences from example 1 are: the temperature of the first polymerization reaction is 75 ℃ and the pressure is 0.6MPa; the second polymerization reaction was carried out at a temperature of 50℃and a pressure of 0.3MPa.
The prepared ultra-high molecular weight polyethylene powder for spinning is marked as UHMWPE-16.
TABLE 7
From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:
as can be seen from comparing examples 1 to 11 and comparative examples 1 to 5, not only ultra-high molecular weight and high toughness polyethylene fibers were obtained by the method provided by the present application, but also ash content was greatly reduced.
It should be noted that the terms "first," "second," and the like in the description and in the claims are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those described herein.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (13)
1. The preparation method of the low ash content ultra-high molecular weight polyethylene resin is characterized in that the ash content in the low ash content ultra-high molecular weight polyethylene resin is less than or equal to 80ppm, the viscosity average molecular weight is 500-800 ten thousand, and the preparation method of the low ash content ultra-high molecular weight polyethylene resin comprises the following steps:
step S1, dividing ethylene into two parts, and carrying out a first polymerization reaction on a first part of ethylene in the presence of an inert atmosphere, a main catalyst and a cocatalyst to obtain a first product system containing a first polymer, wherein the temperature of the first polymerization reaction is 50-60 ℃, the pressure is 0.3-0.6 MPa, the polymerization time is 1-2 h, and the addition amount of ethylene in the step S1 is 20-50% of the total addition amount of ethylene;
and S2, carrying out a second polymerization reaction on the first product system and the rest of ethylene to obtain the low ash content ultra-high molecular weight polyethylene resin, wherein the temperature of the second polymerization reaction is 60-85 ℃, the pressure is 0.6-1.0 MPa, and the polymerization time is 0.5-2 h.
2. The method for producing a low ash ultra high molecular weight polyethylene resin according to claim 1, wherein the method for producing a low ash ultra high molecular weight polyethylene resin comprises:
monitoring the molecular weight of the first polymer in the step S1, and obtaining the first product system when the viscosity average molecular weight of the first polymer is 200-400 ten thousand;
monitoring the product system of the second polymerization reaction in the step S2, and obtaining the low ash ultrahigh molecular weight polyethylene resin when the viscosity average molecular weight of the product system of the second polymerization reaction is 500-800 ten thousand.
3. The method for producing a low ash ultra high molecular weight polyethylene resin according to claim 1 or 2, wherein an α -olefin is further added during the second polymerization reaction.
4. A method for producing a low ash ultra high molecular weight polyethylene resin according to claim 3, wherein said α -olefin is one or more selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene and 1-octene.
5. A method of preparing a low ash ultra high molecular weight polyethylene resin according to claim 3, wherein said α -olefin is used in an amount of not more than 2% by volume based on the volume percentage of said first product system.
6. The method of producing a low ash ultra high molecular weight polyethylene resin according to claim 5, wherein said α -olefin is used in an amount of not more than 1% by volume based on the volume percentage of said first product system.
7. The method for preparing a low ash ultra high molecular weight polyethylene resin according to claim 1, wherein the temperature of the first polymerization reaction is 50 to 55 ℃ and the pressure is 0.3 to 0.5MPa; the temperature of the second polymerization reaction is 75-85 ℃ and the pressure is 0.6-1.0 MPa.
8. The method for producing a low ash ultra high molecular weight polyethylene resin according to claim 1 or 2, wherein a solvent is added to both of the first polymerization process and the second polymerization process.
9. The method for producing a low ash ultra high molecular weight polyethylene resin according to claim 8, wherein said main catalyst is a ziegler natta catalyst;
the cocatalyst is aluminum alkyl.
10. The method for producing a low ash ultra high molecular weight polyethylene resin according to claim 9, wherein said main catalyst is a catalyst of Mg-Ti system.
11. The method for preparing a low ash ultra high molecular weight polyethylene resin according to claim 9, wherein the cocatalyst is triethylaluminum and/or triisobutylaluminum.
12. The method for producing a low ash ultra high molecular weight polyethylene resin according to claim 8, wherein the method for producing a low ash ultra high molecular weight polyethylene resin comprises: and carrying out flash evaporation and centrifugal drying on the product system of the second polymerization reaction in sequence.
13. The method for producing a low ash ultra high molecular weight polyethylene resin according to claim 1, wherein the particle size of the low ash ultra high molecular weight polyethylene resin is 100 to 350 μm and the bulk density is 0.40 to 0.50g/cm 3 。
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