CN117946315A - Method for preparing ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide - Google Patents
Method for preparing ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide Download PDFInfo
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- CN117946315A CN117946315A CN202410356562.3A CN202410356562A CN117946315A CN 117946315 A CN117946315 A CN 117946315A CN 202410356562 A CN202410356562 A CN 202410356562A CN 117946315 A CN117946315 A CN 117946315A
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- ethylene
- carbon dioxide
- tetrafluoroethylene
- supercritical carbon
- monomer
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 128
- 229920000840 ethylene tetrafluoroethylene copolymer Polymers 0.000 title claims abstract description 77
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 64
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 17
- 239000000178 monomer Substances 0.000 claims abstract description 66
- -1 ethylene, tetrafluoroethylene Chemical group 0.000 claims abstract description 46
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims abstract description 26
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 24
- 239000011737 fluorine Substances 0.000 claims abstract description 24
- 239000003999 initiator Substances 0.000 claims abstract description 23
- 239000012986 chain transfer agent Substances 0.000 claims abstract description 22
- 230000009471 action Effects 0.000 claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims description 48
- 238000006116 polymerization reaction Methods 0.000 claims description 46
- 239000005977 Ethylene Substances 0.000 claims description 45
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 41
- GVEUEBXMTMZVSD-UHFFFAOYSA-N 3,3,4,4,5,5,6,6,6-nonafluorohex-1-ene Chemical group FC(F)(F)C(F)(F)C(F)(F)C(F)(F)C=C GVEUEBXMTMZVSD-UHFFFAOYSA-N 0.000 claims description 35
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 claims description 33
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 claims description 21
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 11
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 claims description 8
- 238000002360 preparation method Methods 0.000 claims description 7
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 claims description 5
- RRZIJNVZMJUGTK-UHFFFAOYSA-N 1,1,2-trifluoro-2-(1,2,2-trifluoroethenoxy)ethene Chemical compound FC(F)=C(F)OC(F)=C(F)F RRZIJNVZMJUGTK-UHFFFAOYSA-N 0.000 claims description 4
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 4
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 4
- JLTDJTHDQAWBAV-UHFFFAOYSA-N N,N-dimethylaniline Chemical compound CN(C)C1=CC=CC=C1 JLTDJTHDQAWBAV-UHFFFAOYSA-N 0.000 claims description 4
- 125000000864 peroxy group Chemical group O(O*)* 0.000 claims description 4
- 230000008569 process Effects 0.000 claims description 4
- 239000012966 redox initiator Substances 0.000 claims description 4
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 4
- BLTXWCKMNMYXEA-UHFFFAOYSA-N 1,1,2-trifluoro-2-(trifluoromethoxy)ethene Chemical compound FC(F)=C(F)OC(F)(F)F BLTXWCKMNMYXEA-UHFFFAOYSA-N 0.000 claims description 2
- WUMVZXWBOFOYAW-UHFFFAOYSA-N 1,2,3,3,4,4,4-heptafluoro-1-(1,2,3,3,4,4,4-heptafluorobut-1-enoxy)but-1-ene Chemical compound FC(F)(F)C(F)(F)C(F)=C(F)OC(F)=C(F)C(F)(F)C(F)(F)F WUMVZXWBOFOYAW-UHFFFAOYSA-N 0.000 claims description 2
- UICXTANXZJJIBC-UHFFFAOYSA-N 1-(1-hydroperoxycyclohexyl)peroxycyclohexan-1-ol Chemical compound C1CCCCC1(O)OOC1(OO)CCCCC1 UICXTANXZJJIBC-UHFFFAOYSA-N 0.000 claims description 2
- DAVCAHWKKDIRLY-UHFFFAOYSA-N 1-ethenoxy-1,1,2,2,3,3,3-heptafluoropropane Chemical compound FC(F)(F)C(F)(F)C(F)(F)OC=C DAVCAHWKKDIRLY-UHFFFAOYSA-N 0.000 claims description 2
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 2
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 claims description 2
- 239000000539 dimer Substances 0.000 claims description 2
- 238000007599 discharging Methods 0.000 claims description 2
- FEZFGASTIQVZSC-UHFFFAOYSA-N nonanoyl nonaneperoxoate Chemical compound CCCCCCCCC(=O)OOC(=O)CCCCCCCC FEZFGASTIQVZSC-UHFFFAOYSA-N 0.000 claims description 2
- 230000000379 polymerizing effect Effects 0.000 claims description 2
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 claims description 2
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 2
- 235000010265 sodium sulphite Nutrition 0.000 claims description 2
- 125000002704 decyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 claims 1
- ZQMHJBXHRFJKOT-UHFFFAOYSA-N methyl 2-[(1-methoxy-2-methyl-1-oxopropan-2-yl)diazenyl]-2-methylpropanoate Chemical compound COC(=O)C(C)(C)N=NC(C)(C)C(=O)OC ZQMHJBXHRFJKOT-UHFFFAOYSA-N 0.000 claims 1
- 229920000642 polymer Polymers 0.000 abstract description 14
- 239000002904 solvent Substances 0.000 abstract description 9
- 239000012429 reaction media Substances 0.000 abstract description 5
- 239000003381 stabilizer Substances 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 3
- 230000001376 precipitating effect Effects 0.000 abstract description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 18
- 239000000047 product Substances 0.000 description 18
- 238000005086 pumping Methods 0.000 description 18
- 238000009826 distribution Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 239000007787 solid Substances 0.000 description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 229910052757 nitrogen Inorganic materials 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 239000011347 resin Substances 0.000 description 9
- 229920005989 resin Polymers 0.000 description 9
- 229920002313 fluoropolymer Polymers 0.000 description 6
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 6
- QHSJIZLJUFMIFP-UHFFFAOYSA-N ethene;1,1,2,2-tetrafluoroethene Chemical compound C=C.FC(F)=C(F)F QHSJIZLJUFMIFP-UHFFFAOYSA-N 0.000 description 5
- 239000004811 fluoropolymer Substances 0.000 description 5
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 5
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000007720 emulsion polymerization reaction Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 229920002620 polyvinyl fluoride Polymers 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 238000005345 coagulation Methods 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 239000004205 dimethyl polysiloxane Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000012844 infrared spectroscopy analysis Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001265 acyl fluorides Chemical class 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229920005603 alternating copolymer Polymers 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000012662 bulk polymerization Methods 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004512 die casting Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- WNAHIZMDSQCWRP-UHFFFAOYSA-N dodecane-1-thiol Chemical compound CCCCCCCCCCCCS WNAHIZMDSQCWRP-UHFFFAOYSA-N 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 239000003995 emulsifying agent Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- XUCNUKMRBVNAPB-UHFFFAOYSA-N fluoroethene Chemical compound FC=C XUCNUKMRBVNAPB-UHFFFAOYSA-N 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000010128 melt processing Methods 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- SNGREZUHAYWORS-UHFFFAOYSA-N perfluorooctanoic acid Chemical compound OC(=O)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F SNGREZUHAYWORS-UHFFFAOYSA-N 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 238000002390 rotary evaporation Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000000194 supercritical-fluid extraction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 238000004383 yellowing Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Landscapes
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The invention discloses a method for preparing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide, which comprises the following steps: under the action of an initiator and a chain transfer agent, ethylene, tetrafluoroethylene and a fluorine-containing third monomer are polymerized in a supercritical carbon dioxide medium to obtain an ethylene-tetrafluoroethylene copolymer; the chain transfer agent is polyfluorosiloxane. According to the invention, the polyfluoro siloxane is selected as the chain transfer agent for preparing the ethylene-tetrafluoroethylene copolymer in the supercritical carbon dioxide, the polyfluoro siloxane contains fluorine element and has a certain affinity effect with the ethylene-tetrafluoroethylene copolymer, and the siloxane chain segment of the polyfluoro siloxane is compatible with the supercritical carbon dioxide and plays a role of a stabilizer, so that the polymer is stably suspended in a solvent instead of precipitating out of the system. Solves the problems that when the supercritical carbon dioxide is used as a reaction medium to prepare the fluorine-containing polymer, the solubility of the fluorine-containing polymer in the medium is smaller and the molecular weight of the product is smaller.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and particularly relates to a method for preparing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide.
Background
ETFE (ethylene-tetrafluoroethylene) was an alternating copolymer of ethylene and tetrafluoroethylene, and was first developed by dupont in 1945. ETFE is the toughest fluoroplastic that has PTFE excellent heat, chemical and electrical insulation properties, while also having high light transmission, non-tackiness, good barrier properties, low creep, radiation resistance, high tensile strength, high flexural modulus, high impact strength, and better plasticity and processability. The method is mainly applied to the high-end application fields such as photovoltaic films, release films, building films, aerospace, nuclear industry, electric wires and cables, chemical industry corrosion prevention and the like.
In the polymerization process of ETFE resin, the process safety of emulsion polymerization is relatively high, the product is widely applied, but the post-treatment is complex, the problem of additive residue exists, and the performance of the product is affected. And with the increasing environmental requirements, PFOA used in emulsion polymerization is listed in the forbidden chemical list, the product application is limited, and the existing polymerization process faces substitution risks and challenges in the future. The solution polymerization method can produce ETFE resin with excellent performance and good processability, but the solution polymerization uses a large amount of fluorinated solvent in the production process, which causes a large amount of fluorinated solvent to volatilize to the atmosphere, resulting in waste of energy and serious environmental pollution. And a great disadvantage of the solution polymerization is that the ETFE resin has a relatively wide molecular weight distribution. Excessive low molecular weight resins can lead to more raw material loss and energy consumption for later devolatilization. When the devolatilization effect is poor, the problems of casting die casting, color change, product foaming, mold pollution and the like are brought to ETFE processing. While too high a molecular weight can introduce residual stress into the ETFE article leading to dimensional stability problems such as shrinkage, distortion, etc.
Therefore, the supercritical polymerization technology is in the spotlight, the preparation of fluoropolymers using SC-CO 2 as the reaction medium is mostly focused on amorphous fluoropolymers, and the preparation technology of fluoropolymers using SC-CO 2 as the reaction medium for crystallization is not mature. CN109810213a discloses a fluoropolymer under a water/supercritical carbon dioxide mixed system and a preparation method. The invention uses the water/supercritical carbon dioxide mixed system as a medium, can control the problems of heat and viscosity existing in bulk and solution polymerization, and improves the production efficiency. In addition, the fluorine-containing polymer prepared by the invention can be separated from an aqueous phase, has high product purity, simple post-treatment, small yellowing, low melt index and easy processing, and the molecular weight distribution coefficient (PDI) is generally between 1.5 and 2.5 and is smaller than various reported methods. However, mixed systems result in lower monomer concentrations, slower polymerization rates, lower equipment throughput and utilization, and lower polymer molecular weights due to lower monomer concentrations and transfer to solvent chains. CN103304720a discloses a preparation method of a polyvinyl fluoride copolymer in supercritical carbon dioxide, under the action of a free radical initiator, a vinyl fluoride monomer and other fluorine-containing monomers are contacted together in a polymerization medium of supercritical carbon dioxide and polymerized to obtain the polyvinyl fluoride copolymer. The preparation method provided by the invention realizes the melt processing of the polyvinyl fluoride copolymer and the improvement of the appearance and the performance of the product. However, the prepared fluorine-containing polymer has smaller solubility in the medium and low conversion rate due to no stabilizer.
It is generally known that supercritical carbon dioxide (Supercritical carbon dioxide, SC-CO 2) has the following advantages as a medium for polymerization compared to conventional polymerization media: (1) is nontoxic, low in cost, and fast in mass and heat transfer speed; (2) Toxic residual initiator and decomposition products can be easily removed by an SC-CO 2 extraction technology; (3) The dissolution capacity for monomers and polymers can be varied by adjusting the pressure and temperature thereof; (4) By utilizing the supercritical extraction technology, the product with high purity can be obtained at the same time.
However, as is clear from the above disclosed preparation method, supercritical carbon dioxide as a reaction medium for preparing fluoropolymers still has the following drawbacks in polymerization: the prepared fluorine-containing polymer has smaller solubility in a medium and small molecular weight of a product, so that a series of problems of coagulation, easy adhesion of the product to a kettle and a stirring paddle, difficult control of reaction temperature, wide molecular weight distribution and the like can be caused by the fact that the product is separated out of a system too early.
Disclosure of Invention
In order to solve the defects in the prior art, the invention discloses a method for preparing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide, which adopts the following technical scheme:
A process for preparing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide comprising the steps of: under the action of an initiator and a chain transfer agent, ethylene, tetrafluoroethylene and a fluorine-containing third monomer are polymerized in a supercritical carbon dioxide medium to obtain an ethylene-tetrafluoroethylene copolymer; the chain transfer agent is polyfluorosiloxane.
The invention selects the polyfluoro siloxane as the chain transfer agent, the polyfluoro siloxane contains fluorine element, has certain affinity with the ethylene-tetrafluoroethylene copolymer, and the siloxane chain segment of the polyfluoro siloxane is compatible with supercritical carbon dioxide to play a role of a stabilizer, so that the polymer is stably suspended in a solvent instead of precipitating out of the system. The ETFE product prepared by the method has larger molecular weight, narrower molecular weight distribution, higher yield strength and better tensile creep resistance and compression resistance, and the advantages are very important in extrusion, granulation, injection molding and other process applications. Compared with the existing solution polymerization and emulsion polymerization processes, the method has the advantages of simple post-treatment, no emulsifier residue and meeting the increasingly stringent environmental protection requirements. The solvent can be separated and recycled, so that the production cost is reduced.
Further, the polyfluoro siloxane is one or a combination of methyl acrylate end-capped poly (3, 3-trifluoropropyl) methyldiethyl siloxane, acrylic acid end-capped poly (3, 3-trifluoropropyl) methyldiethyl siloxane, methyl acrylate end-capped poly (perfluorodecyl trimethyl siloxane) and acrylic acid end-capped poly (perfluorodecyl trimethyl siloxane), and preferably, the polyfluoro siloxane is acrylic acid end-capped poly (perfluorodecyl trimethyl siloxane).
The polyfluoro siloxane has amphiphilic property, and besides the compatibility of the siloxane chain segment of the polyfluoro siloxane and supercritical carbon dioxide, the polyfluoro siloxane plays a role of a stabilizer, so that the polymer is stably suspended in a solvent instead of being precipitated out of a system, and single-end active groups participate in polymerization to play roles of anchoring and chain transfer. The molecular weight of ETFE can be further improved to make its molecular weight distribution narrower. The prepared ETFE copolymer has better performance. Among them, acrylic acid-terminated polyperfluorodecyl trimethylsiloxane is most effective.
Further, the initiator is one or a combination of azo initiator, peroxy initiator and redox initiator, preferably, the azo initiator is one or a combination of azobisisobutyronitrile, azobisisoheptonitrile and azobisisobutyronitrile; the peroxy initiator is one or a combination of perfluoro oxaacyl nonanoyl peroxide, hexafluoroepoxy dimer acyl fluoride peroxide and perfluoro diethyl peroxydicarbonate; the redox initiator is one or a combination of hydrogen peroxide/sodium sulfite, sodium persulfate/sodium bisulfite and cyclohexanone peroxide/N, N-dimethylaniline.
Further, the third monomer containing fluorine is one or a combination of perfluoro vinyl ether and perfluoroalkyl ethylene, preferably, the perfluoro vinyl ether is one or a combination of perfluoro n-propyl vinyl ether, perfluoro methyl vinyl ether and perfluoro ethyl vinyl ether; the perfluoroalkyl ethylene is one or a combination of perfluoromethyl ethylene and perfluorobutyl ethylene.
Further, the polymerization degree of the chain transfer agent is 5-20. The stability of ETFE in supercritical carbon dioxide can be changed by adjusting the polymerization degree of the chain transfer agent, so that the purpose of obtaining products with different solid contents is achieved, wherein the solid contents refer to the percentage of the mass of the obtained ETFE copolymer to the total mass of a system composed of the ETFE copolymer and the supercritical carbon dioxide medium after the reaction is finished.
Further, the initiator is used in an amount of 0.3-2% of the total mass of the polymerized monomers;
further, the amount of the chain transfer agent is 0.1-1% of the total mass of the polymerized monomers.
Further, the reaction temperature in the polymerization process is 35-80 ℃, the pressure is 8-20 MPa, and the time is 2-8 hours.
Further, the specific operation steps of polymerizing ethylene, tetrafluoroethylene and fluorine-containing third monomer in supercritical carbon dioxide medium under the action of an initiator and a chain transfer agent to obtain the ethylene-tetrafluoroethylene copolymer are as follows:
(1) Evacuating the reaction kettle, introducing carbon dioxide into the reaction kettle, wherein the ratio of the mass of the carbon dioxide to the total mass of the polymerized monomers is 0.5-5:1, heating the reaction kettle, and keeping the temperature in the reaction kettle at 35-80 ℃;
(2) Adding a chain transfer agent into a reaction kettle, introducing an initial mixed monomer until the pressure in the kettle is 8-20MPa, enabling carbon dioxide to be in a supercritical state, wherein the mole ratio of tetrafluoroethylene monomer in the initial mixed monomer is 75-90%, the mole ratio of ethylene monomer is 8-20%, the mole ratio of fluorine-containing third monomer is 1-5%, adding an initiator into the reaction kettle, and starting polymerization, wherein the use amount of the initiator is 0.3-2% of the total mass of polymerized monomers;
(3) Adding mixed monomers into a reaction kettle in the polymerization process to maintain the pressure in the kettle at 8-20MPa, wherein in the added mixed monomers, the molar ratio of tetrafluoroethylene monomer is 45-70%, the molar ratio of ethylene monomer is 25-50%, the molar ratio of fluorine-containing third monomer is 1-5%, carbon dioxide is in a supercritical state, reacting for 2-8 hours, and recovering or discharging carbon dioxide after cooling or depressurization to obtain the ethylene-tetrafluoroethylene copolymer.
The total mass of the polymerized monomer is the total mass of ethylene, tetrafluoroethylene and fluorine-containing third monomer which participate in the polymerization reaction, the total mass of ethylene, tetrafluoroethylene and fluorine-containing third monomer which are required to be consumed in the polymerization reaction can be calculated according to the solid content of ETFE copolymer which is required to be prepared in actual production, and the solid content of the ETFE copolymer is the percentage of the mass of the ETFE copolymer to the total mass of a system consisting of the supercritical carbon dioxide solvent and the ETFE copolymer after the reaction is completed.
The invention also discloses an ethylene-tetrafluoroethylene copolymer, which is prepared by adopting any one of the methods for preparing the ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide. Preferably, the ethylene-tetrafluoroethylene copolymer has a PDI of less than 2.0.
By adopting the technical scheme, the invention has the beneficial effects that:
According to the invention, the polyfluoro siloxane is selected as the chain transfer agent for preparing the ethylene-tetrafluoroethylene copolymer in the supercritical carbon dioxide, the polyfluoro siloxane contains fluorine element and has a certain affinity effect with the ethylene-tetrafluoroethylene copolymer, and the siloxane chain segment of the polyfluoro siloxane is compatible with the supercritical carbon dioxide and plays a role of a stabilizer, so that the polymer is stably suspended in a solvent instead of precipitating out of the system. Solves the problems that when the supercritical carbon dioxide is used as a reaction medium to prepare the fluorine-containing polymer, the solubility of the fluorine-containing polymer in the medium is smaller and the molecular weight of the product is smaller. The method also solves a series of problems of low solubility, easy coagulation and sedimentation caused by low molecular weight of the product, easy adhesion of the product to a kettle and a stirring paddle, difficult control of reaction temperature, wide molecular weight distribution and the like. The prepared ETFE copolymer has the advantages of larger molecular weight, narrower molecular weight distribution, higher yield strength and better tensile creep resistance and compression resistance.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The raw materials used in the examples and comparative examples were all common commercial products.
The test methods for each property of ETFE copolymers prepared in examples and comparative examples are as follows:
1. Melt index (MFI, g/10 min), according to the specification of GB/T3682.1-2018, wherein the test load is 5kg and the temperature is 297 ℃.
2. Melting point (Tm, DEG C), accurately weighing 10mg + -0.5 mg of sample according to the specification of GB/T19466.3-2004, heating to 320 ℃ at a heating rate of 20 ℃/min in nitrogen atmosphere, so that the ETFE resin is completely melted, and taking the melting peak top temperature as the melting point of the copolymer.
3. The tensile strength and the elongation at break are carried out according to the specification of GB/T2918-2018, wherein the test environment temperature is 23+/-2 ℃, the stretching speed is 50 mm/min+/-5 mm/min, the lengths of two ends of a clamp clamping sample are equal, and the clamp spacing is 24mm.
4. ETFE copolymer composition (mol%) as determined by infrared spectroscopic analysis.
5. Unstable end groups, as determined by infrared spectroscopic analysis.
6. ETFE oligomer content (wt%) 30g of the ETFE resin prepared in the examples or comparative examples and 300g of 1, 3-dichloro-1, 2, 3-pentafluoropropane were charged into a PTFE-lined pressure vessel, and heat treated in a furnace at 150℃for 12 hours. The pressure vessel was cooled to room temperature, a mixture of ETFE and 1, 3-dichloro-1, 2, 3-pentafluoropropane was filtered, and the amount of the extracted ETFE oligomer was measured by completely evaporating 1, 3-dichloro-1, 2, 3-pentafluoropropane contained in the filtrate by rotary evaporation.
7. PDI, obtained by dividing the weight average molecular weight of the ETFE copolymer by the number average molecular weight, wherein the weight average molecular weight, number average molecular weight, are both obtained by the rotorheological test.
8. Solids content (wt%) after the end of the reaction of the examples or comparative examples, the mass of ETFE copolymer is the ratio of the mass of ETFE copolymer to the total mass of recovered carbon dioxide.
Example 1
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 3 parts by mass of methyl acrylate-terminated poly (3, 3-trifluoropropyl) methyldiethylsiloxane with the polymerization degree of 5 into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Example 2
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 3 parts by mass of methyl acrylate-terminated poly (3, 3-trifluoropropyl) methyldiethylsiloxane with the polymerization degree of 20 into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Example 3
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 3 parts by mass of acrylic acid-terminated poly (perfluorodecyl) trimethylsiloxane with the polymerization degree of 5 into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Example 4
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 3 parts by mass of acrylic acid-terminated poly (3, 3-trifluoropropyl) methyldiethylsiloxane with the polymerization degree of 5 into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Example 5
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 3 parts by mass of methyl acrylate-terminated poly (perfluorodecyl) trimethylsiloxane with the polymerization degree of 5 into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Example 6
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 3 parts by mass of poly (perfluorodecyl) trimethylsiloxane with the polymerization degree of 5 into the kettle through the metering pump (without end capping). The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Example 7
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 3 parts by mass of vinyl-terminated poly (perfluorodecyl) trimethylsiloxane with the polymerization degree of 5 into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Comparative example 1
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of carbon dioxide into the reaction kettle through a metering pump, heating the reaction kettle to 70 ℃, and pumping 9 parts by mass of polydimethylsiloxane into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was added to the kettle by a compressor until the pressure was 11MPa, and then perfluorobutyl ethylene (tetrafluoroethylene/ethylene/perfluorobutyl ethylene molar ratio=82:17:1) was added. After the temperature and pressure were stabilized, 10 parts by mass of azobisisobutyronitrile was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 11MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/perfluorobutyl ethylene=51.3:46.8:1.9) through a metering pump, cooling after reacting for 6 hours, recovering carbon dioxide and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
Comparative example 2
And evacuating the 5L reaction kettle, replacing nitrogen for more than five times to ensure that the oxygen content is lower than 10ppm, pumping 2000 parts by mass of F113 into the reaction kettle through a metering pump, heating the reaction kettle to 50 ℃, and pumping 5 parts by mass of n-dodecyl mercaptan into the kettle through the metering pump. The tetrafluoroethylene/ethylene mixed monomer was fed into the kettle by a compressor until the pressure was 11MPa, and hexafluoropropylene was added (tetrafluoroethylene/ethylene/hexafluoropropylene molar ratio=82:16.8:1.2). After the temperature and pressure were stabilized, 10 parts by mass of methanol was added to start polymerization. Continuously adding mixed monomers of tetrafluoroethylene/ethylene through a compressor to maintain the system pressure at 2MPa in the polymerization process, continuously adding perfluorobutyl ethylene (molar ratio of tetrafluoroethylene/ethylene/hexafluoropropylene=51.3:46.8:1.9) through a metering pump, reacting for 3 hours, cooling, recovering F113 and unreacted monomers, and collecting materials to obtain the ETFE copolymer.
The properties of ETFE copolymers prepared in each example and comparative example are shown in table 1:
Table 1 shows the product properties of the examples/comparative examples
As can be seen from Table 1, the resins prepared in examples 1 to 7 have relatively excellent mechanical properties and relatively narrow molecular weight distribution, and in particular, the PDI of the ETFE copolymers prepared in examples 1 to 5 are all within 2; the absence of unstable end groups, as determined by infrared, with no significant absorption at 1777, 1812 and 1883cm -1, indicates that the absence of unstable carboxylic acid (-COOH 1777 and 1812cm -1) and acyl fluoride (-COF, 1883cm -1) end groups in the ETFE polymer prepared in SC-CO 2; the ETFE oligomer content was low, and in particular, the ETFE copolymers prepared in examples 1-5 generally had an oligomer content of less than 0.15wt%.
As is clear from examples 1 and 2, the purpose of increasing the solid content can be achieved by increasing the polymerization degree of the chain transfer agent.
From examples 1 and 3 to 7, it is known that the use of methyl acrylate-terminated poly (3, 3-trifluoropropyl) methyldiethylsiloxane, acrylic acid-terminated poly (3, 3-trifluoropropyl) methyldiethylsiloxane, methyl acrylate-terminated poly (perfluorodecyl trimethylsiloxane), and acrylic acid-terminated poly (perfluorodecyl trimethylsiloxane) as chain transfer agent can make the resin have better solid content, narrower molecular weight distribution and better resin properties than the use of non-terminal polyfluoro siloxane and other terminal polyfluoro siloxanes as chain transfer agent.
From examples 1 and 3 to 5, the acrylic acid-terminated poly (perfluorodecyl) trimethicone gives the best resin solids content, the narrowest molecular weight distribution and the best resin properties.
The resin prepared in comparative example 1, the chain transfer agent was polydimethylsiloxane, and the solid content of the prepared resin was low.
The resin prepared in comparative example 2 adopts a conventional solution polymerization mode, and has relatively wide molecular weight distribution, high oligomer content, low equipment utilization rate and about 10% of upper limit of solid content.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, those skilled in the art may still make modifications to the technical solutions described in the foregoing embodiments, or may make equivalent substitutions for some or all of the technical features thereof; such modifications and substitutions do not depart from the spirit of the invention, and are intended to be included within the scope of the appended claims and description.
Claims (10)
1. A process for preparing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide, comprising the steps of:
Under the action of an initiator and a chain transfer agent, ethylene, tetrafluoroethylene and a fluorine-containing third monomer are polymerized in a supercritical carbon dioxide medium to obtain an ethylene-tetrafluoroethylene copolymer;
The chain transfer agent is polyfluorosiloxane.
2. The method for producing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide according to claim 1, wherein: the polyfluorosiloxane is one or a combination of methyl acrylate end-capped poly (3, 3-trifluoropropyl) methyldiethyl siloxane, acrylic acid end-capped poly (3, 3-trifluoropropyl) methyldiethyl siloxane, methyl acrylate end-capped poly (perfluorodecyl trimethyl siloxane) and acrylic acid end-capped poly (perfluorodecyl trimethyl siloxane).
3. The method for producing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide according to claim 1, wherein: the polyfluoro siloxane is acrylic acid end-capped polyfluoro decyl trimethyl siloxane.
4. The method for producing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide according to claim 1, wherein: the initiator is one or the combination of azo initiator, peroxy initiator and redox initiator,
The azo initiator is one or a combination of azodiisobutyronitrile, azodiisoheptonitrile and dimethyl azodiisobutyrate;
The peroxy initiator is one or a combination of perfluoro oxaacyl nonanoyl peroxide, hexafluoroepoxy dimer acyl fluoride peroxide and perfluoro diethyl peroxydicarbonate;
The redox initiator is one or a combination of hydrogen peroxide/sodium sulfite, sodium persulfate/sodium bisulfite and cyclohexanone peroxide/N, N-dimethylaniline.
5. The method for producing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide according to claim 1, wherein: the third monomer containing fluorine is one or the combination of perfluoro vinyl ether and perfluoroalkyl ethylene,
The perfluoro vinyl ether is one or a combination of perfluoro-n-propyl vinyl ether, perfluoro methyl vinyl ether and perfluoro ethyl vinyl ether;
the perfluoroalkyl ethylene is one or a combination of perfluoromethyl ethylene and perfluorobutyl ethylene.
6. Process for the preparation of ethylene-tetrafluoroethylene copolymers in supercritical carbon dioxide according to claim 1 or 2, characterized in that: the polymerization degree of the chain transfer agent is 5-20;
the initiator is used in an amount of 0.3-2% of the total mass of the polymerized monomers;
The chain transfer agent is used in an amount of 0.1-1% of the total mass of the polymerized monomers.
7. The method for producing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide according to claim 1, wherein: the reaction temperature in the polymerization process is 35-80 ℃, the pressure is 8-20 MPa, and the time is 2-8 hours.
8. The method for producing an ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide according to claim 1, wherein: the specific operation steps of polymerizing ethylene, tetrafluoroethylene and fluorine-containing third monomer in supercritical carbon dioxide medium under the action of initiator and chain transfer agent are as follows:
(1) Introducing carbon dioxide into the reaction kettle after evacuating the reaction kettle, wherein the ratio of the mass of the carbon dioxide to the total mass of the polymerized monomers is 0.5-5:1, heating the reaction kettle, and keeping the temperature in the kettle at 35-80 ℃;
(2) Adding a chain transfer agent into a reaction kettle, introducing an initial mixed monomer until the pressure in the kettle is 8-20MPa, wherein the molar ratio of tetrafluoroethylene monomer in the initial mixed monomer is 75-90%, the molar ratio of ethylene monomer is 8-20%, the molar ratio of fluorine-containing third monomer is 1-5%, adding an initiator into the reaction kettle, wherein the dosage of the initiator is 0.3-2% of the total mass of polymerized monomers, and starting polymerization;
(3) In the polymerization process, adding mixed monomers into a reaction kettle to maintain the pressure in the kettle at 8-20MPa, wherein in the added mixed monomers, the molar ratio of tetrafluoroethylene monomer is 45-70%, the molar ratio of ethylene monomer is 25-50%, the molar ratio of fluorine-containing third monomer is 1-5%, reacting for 2-8 hours, and recovering or discharging carbon dioxide after cooling or depressurizing to obtain the ethylene-tetrafluoroethylene copolymer.
9. An ethylene-tetrafluoroethylene copolymer characterized in that: the method for preparing ethylene-tetrafluoroethylene copolymer in supercritical carbon dioxide according to any one of claims 1 to 8.
10. The ethylene-tetrafluoroethylene copolymer according to claim 9, wherein: the PDI is less than 2.0.
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| CN1242021A (en) * | 1996-12-23 | 2000-01-19 | 纳幕尔杜邦公司 | Polymerization of fluoromonomers in carbon dioxide |
| US20060235175A1 (en) * | 2005-04-15 | 2006-10-19 | Bilal Baradie | Synthesis and characterization of novel functional fluoropolymers |
| CN108239214A (en) * | 2016-12-27 | 2018-07-03 | 浙江蓝天环保高科技股份有限公司 | A kind of method that continuous polymerization in supercritical carbon dioxide prepares polyvinyl fluoride copolymer |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1242021A (en) * | 1996-12-23 | 2000-01-19 | 纳幕尔杜邦公司 | Polymerization of fluoromonomers in carbon dioxide |
| US20060235175A1 (en) * | 2005-04-15 | 2006-10-19 | Bilal Baradie | Synthesis and characterization of novel functional fluoropolymers |
| CN108239214A (en) * | 2016-12-27 | 2018-07-03 | 浙江蓝天环保高科技股份有限公司 | A kind of method that continuous polymerization in supercritical carbon dioxide prepares polyvinyl fluoride copolymer |
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