CN113402647B - Regulation and control method and synthesis method of synthetic EVA with controllable release of free radical, EVOH resin and synthesis method thereof - Google Patents
Regulation and control method and synthesis method of synthetic EVA with controllable release of free radical, EVOH resin and synthesis method thereof Download PDFInfo
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- CN113402647B CN113402647B CN202011626536.6A CN202011626536A CN113402647B CN 113402647 B CN113402647 B CN 113402647B CN 202011626536 A CN202011626536 A CN 202011626536A CN 113402647 B CN113402647 B CN 113402647B
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- 229920000219 Ethylene vinyl alcohol Polymers 0.000 title claims abstract description 101
- UFRKOOWSQGXVKV-UHFFFAOYSA-N ethene;ethenol Chemical compound C=C.OC=C UFRKOOWSQGXVKV-UHFFFAOYSA-N 0.000 title claims abstract description 96
- 239000004715 ethylene vinyl alcohol Substances 0.000 title claims abstract description 96
- 229920005989 resin Polymers 0.000 title claims abstract description 64
- 239000011347 resin Substances 0.000 title claims abstract description 64
- 238000001308 synthesis method Methods 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 title abstract description 45
- 150000003254 radicals Chemical class 0.000 title abstract description 28
- 239000002904 solvent Substances 0.000 claims abstract description 62
- 238000010438 heat treatment Methods 0.000 claims abstract description 53
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 51
- 239000003999 initiator Substances 0.000 claims abstract description 47
- 238000009826 distribution Methods 0.000 claims abstract description 31
- 230000001276 controlling effect Effects 0.000 claims abstract description 23
- 238000005227 gel permeation chromatography Methods 0.000 claims abstract description 18
- 230000001105 regulatory effect Effects 0.000 claims abstract description 17
- 230000002902 bimodal effect Effects 0.000 claims abstract description 13
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 108
- 238000006243 chemical reaction Methods 0.000 claims description 97
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 92
- 239000005977 Ethylene Substances 0.000 claims description 92
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 57
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 42
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 33
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 32
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 30
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 30
- 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 28
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 21
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 20
- 239000003054 catalyst Substances 0.000 claims description 20
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 20
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 19
- 239000002994 raw material Substances 0.000 claims description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 238000001556 precipitation Methods 0.000 claims description 18
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 16
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 12
- -1 amyl neodecanoate peroxide Chemical class 0.000 claims description 11
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 10
- 239000004327 boric acid Substances 0.000 claims description 10
- 238000010528 free radical solution polymerization reaction Methods 0.000 claims description 10
- 235000006408 oxalic acid Nutrition 0.000 claims description 10
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 10
- WFUGQJXVXHBTEM-UHFFFAOYSA-N 2-hydroperoxy-2-(2-hydroperoxybutan-2-ylperoxy)butane Chemical compound CCC(C)(OO)OOC(C)(CC)OO WFUGQJXVXHBTEM-UHFFFAOYSA-N 0.000 claims description 8
- 239000004342 Benzoyl peroxide Substances 0.000 claims description 8
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 claims description 8
- 235000019400 benzoyl peroxide Nutrition 0.000 claims description 8
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 8
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 7
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 claims description 7
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 7
- 239000003208 petroleum Substances 0.000 claims description 7
- 230000035484 reaction time Effects 0.000 claims description 7
- RPBWMJBZQXCSFW-UHFFFAOYSA-N 2-methylpropanoyl 2-methylpropaneperoxoate Chemical compound CC(C)C(=O)OOC(=O)C(C)C RPBWMJBZQXCSFW-UHFFFAOYSA-N 0.000 claims description 6
- 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 description 6
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 6
- RCEJCSULJQNRQQ-UHFFFAOYSA-N 2-methylbutanenitrile Chemical compound CCC(C)C#N RCEJCSULJQNRQQ-UHFFFAOYSA-N 0.000 claims description 5
- ZGPBOPXFOJBLIV-UHFFFAOYSA-N butoxycarbonyloxy butyl carbonate Chemical compound CCCCOC(=O)OOC(=O)OCCCC ZGPBOPXFOJBLIV-UHFFFAOYSA-N 0.000 claims description 5
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 5
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims description 4
- GJBRNHKUVLOCEB-UHFFFAOYSA-N tert-butyl benzenecarboperoxoate Chemical compound CC(C)(C)OOC(=O)C1=CC=CC=C1 GJBRNHKUVLOCEB-UHFFFAOYSA-N 0.000 claims description 4
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 claims description 3
- 239000000243 solution Substances 0.000 claims description 3
- 238000010189 synthetic method Methods 0.000 claims 1
- 239000005038 ethylene vinyl acetate Substances 0.000 abstract description 98
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 abstract description 98
- 230000000694 effects Effects 0.000 abstract description 18
- 230000002194 synthesizing effect Effects 0.000 abstract description 17
- 238000003786 synthesis reaction Methods 0.000 abstract description 11
- 230000000977 initiatory effect Effects 0.000 abstract description 9
- 230000015572 biosynthetic process Effects 0.000 abstract description 8
- 239000002131 composite material Substances 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 abstract description 3
- 239000000047 product Substances 0.000 description 29
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- 229920000642 polymer Polymers 0.000 description 14
- 239000007789 gas Substances 0.000 description 13
- 238000005481 NMR spectroscopy Methods 0.000 description 10
- 230000004888 barrier function Effects 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- 239000008367 deionised water Substances 0.000 description 8
- 229910021641 deionized water Inorganic materials 0.000 description 8
- 238000001035 drying Methods 0.000 description 8
- 239000012046 mixed solvent Substances 0.000 description 7
- 229910001220 stainless steel Inorganic materials 0.000 description 7
- 239000010935 stainless steel Substances 0.000 description 7
- 239000003502 gasoline Substances 0.000 description 6
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 4
- 230000001133 acceleration Effects 0.000 description 4
- 238000006136 alcoholysis reaction Methods 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 4
- WPPLKRDOKPISSC-UHFFFAOYSA-N pentyl 2,2-dimethylpropaneperoxoate Chemical compound CCCCCOOC(=O)C(C)(C)C WPPLKRDOKPISSC-UHFFFAOYSA-N 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 238000010526 radical polymerization reaction Methods 0.000 description 4
- 239000011541 reaction mixture Substances 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- FSRYENDEMMDKMT-UHFFFAOYSA-N butoxy ethaneperoxoate Chemical compound CCCCOOOC(C)=O FSRYENDEMMDKMT-UHFFFAOYSA-N 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 229910000027 potassium carbonate Inorganic materials 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- DTGWMJJKPLJKQD-UHFFFAOYSA-N butyl 2,2-dimethylpropaneperoxoate Chemical compound CCCCOOC(=O)C(C)(C)C DTGWMJJKPLJKQD-UHFFFAOYSA-N 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 238000000655 nuclear magnetic resonance spectrum Methods 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- ZLAJWQIJAVXCAT-UHFFFAOYSA-N pentyl 7,7-dimethyloctaneperoxoate Chemical compound CCCCCOOC(=O)CCCCCC(C)(C)C ZLAJWQIJAVXCAT-UHFFFAOYSA-N 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 238000005191 phase separation Methods 0.000 description 2
- 230000000379 polymerizing effect Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- DCKVNWZUADLDEH-UHFFFAOYSA-N sec-butyl acetate Chemical group CCC(C)OC(C)=O DCKVNWZUADLDEH-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VRHVJSKHTCZHDV-UHFFFAOYSA-N C(CCCCCC(C)(C)C)(=O)OOCC(C)(C)C Chemical compound C(CCCCCC(C)(C)C)(=O)OOCC(C)(C)C VRHVJSKHTCZHDV-UHFFFAOYSA-N 0.000 description 1
- 229920002978 Vinylon Polymers 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- HFUSECPXGUISGB-UHFFFAOYSA-N benzoyl benzenecarboperoxoate;2-tert-butylperoxy-2-methylpropane Chemical compound CC(C)(C)OOC(C)(C)C.C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 HFUSECPXGUISGB-UHFFFAOYSA-N 0.000 description 1
- UBAZGMLMVVQSCD-UHFFFAOYSA-N carbon dioxide;molecular oxygen Chemical compound O=O.O=C=O UBAZGMLMVVQSCD-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000013270 controlled release Methods 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006009 resin backbone Polymers 0.000 description 1
- 229920006126 semicrystalline polymer Polymers 0.000 description 1
- 238000012163 sequencing technique Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F210/02—Ethene
-
- 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
- C08F8/00—Chemical modification by after-treatment
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The invention provides an EVOH resin, and the gel permeation chromatography curve of the EVOH resin is in a double-peak form. The invention is based on the controllable release of initiator free radicals, and realizes the regulation and control of EVA structure, molecular weight and the like by regulating and controlling the feeding mode, the solvent effect, the pulse heating and the composite initiator according to the relation between the polymerization reaction dynamics characteristic and the free radical concentration, the generation rate and the initiation efficiency and the self-acceleration phenomenon. In particular, the prepared EVA is used for synthesizing EVOH (ethylene-vinyl alcohol copolymer) resin, and Gel Permeation Chromatography (GPC) test shows that EVOH resin with bimodal distribution can be obtained by the regulating method provided by the invention. The regulation and control method and the synthesis method for preparing EVA (ethylene-vinyl acetate copolymer) with controllable structure provided by the invention have the characteristics of strong controllability, mild condition, simplicity in operation and large-scale synthesis prospect.
Description
Technical Field
The invention belongs to the technical field of EVA and EVOH resin synthesis, and relates to a regulation and control method and a synthesis method of synthetic EVA, an EVOH resin and a synthesis method thereof, in particular to a regulation and control method and a synthesis method of synthetic EVA with controllable release of free radicals, and an EVOH resin and a synthesis method thereof.
Background
With the rapid development of the automobile industry, the consumption of fuel oil, particularly gasoline, is enormous, and the demand is still increasing exponentially year by year. However, the main component of gasoline is light hydrocarbon organic matters (VOC) which are easy to volatilize, and since the container for storing gasoline, such as an automobile tank, a transportation tank, a storage tank and the like, is made of metal, the barrier property to the VOC is poor, and particularly, after the volatilization of the gasoline forms a certain vapor pressure in the container, the volatile gasoline is easier to diffuse and permeate out of the container, thereby causing great harmful substances to people, environment and living beings. Therefore, VOC abatement is also a further important project following automotive exhaust abatement. With the method as a starting point, the barrier property of the gasoline container to light hydrocarbon organic matters is improved, VOC can be reduced, the environment is relieved, the oil utilization efficiency is improved, the cost is saved, and the resource waste is reduced. EVOH (ethylene-vinyl alcohol copolymer) is a semi-crystalline polymer material with excellent gas (such as oxygen, carbon dioxide and the like) barrier property and processability, and is used for oil containers in the form of interlayers or coatings to remarkably reduce the permeation of light hydrocarbon VOC. Industrially, EVOH is synthesized from ethylene and vinyl acetate as raw materials by preparing EVA by free radical initiated solution polymerization and alcoholysis. EVOH synthesis work was performed by Nanjing woodization (forest chemical industry communication, 1995, 6, 3-6; CN 91107038.9), and then related work was performed by Sichuan vinylon works, china petrochemical group (CN 201510184602.1; CN 201310125550.1). At present, EVOH products are mainly prepared by directly processing and modifying purchased EVOH resin, but the EVOH synthesis technology does not reach the industrialized production stage yet.
The excellent barrier property of EVOH benefits from the strong bonding effect between hydroxyl groups in molecules and intermolecular hydrogen bonds, the cohesive force is strong, molecular chains are closely stacked, and small molecules cannot permeate; on the other hand, the presence of ethylene segments imparts good processability to EVOH. At present, a great deal of reports are made on regulating and controlling the barrier property and the processing property of a polymer by controlling the ethylene content in EVOH, however, the problems of poor controllability of the polymerization process, poor linearity of a polymer structure and the like, such as low molecular weight of the polymer, uneven distribution of hydroxyl groups on a main chain or occurrence of branched chains, high branching degree or uncontrollable branching, and the like, finally result in low molecular weight of the EVOH, unstable batch and poor structural controllability.
Therefore, how to realize the controllable polymerization of ethylene and vinyl acetate has important significance for further improving the barrier property and the processability of EVOH and improving the product batch stability, and is one of the problems to be solved by a plurality of researchers with foreseeability in the field.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a method for controlling and synthesizing EVA, an EVOH resin and a method for synthesizing the same, and in particular, a method for controlling and synthesizing EVA with controllable release of free radicals. According to the EVA regulation and control method provided by the invention, ethylene and vinyl acetate are used as raw materials, EVA is prepared in a free radical solution polymerization system, and the EVA for preparing the EVOH can be better controllable by regulating and controlling the structure of the EVA through the controllable release of free radicals based on the relation between the polymerization reaction dynamics characteristic and the concentration, the generation rate and the initiation efficiency of the free radicals and the self-acceleration phenomenon.
The invention provides an EVOH resin, which is characterized in that the gel permeation chromatography curve of the EVOH resin is in a double-peak form.
Preferably, the weight average molecular weight of the first peak in the double peaks is 6.92-8.70 kg/mol;
the weight average molecular weight of the second peak in the double peaks is 4.38-7.15 kg/mol;
the molecular weight distribution PDI of the EVOH resin is 3.6-6.8;
the branching degree of the EVOH resin is 1000 CH/1000 CH 2 And 50 or less mid-branched chains.
The invention provides a regulation and control method for synthesizing EVA, which comprises the following steps:
a) Setting a feeding mode and a feeding sequence of ethylene and vinyl acetate based on the initiation speed of an initiator on the ethylene and the vinyl acetate;
b) Setting the selection, the number and the addition mode of the initiator based on the automatic acceleration effect of the free radical polymerization reaction;
c) Setting the type of solvent and/or the number of solvents based on the chain transfer constant of the solvent, the solubility of ethylene in the solvent, the solubility of vinyl acetate in the solvent and the distribution coefficient of ethylene in the vinyl acetate and the solvent, so as to regulate and control the structure and/or the molecular weight of the synthesized EVA;
when the number of the solvents is more than or equal to 2, the step c) further comprises a distribution coefficient of the vinyl acetate in the mixed solvent;
d) Setting a heating mode of the synthesis reaction based on the relation between the free radical generated by the initiator and the temperature;
the above steps of the regulation method are not in sequence.
The invention provides an EVA synthesis method based on the regulation and control method, which comprises the following steps:
1') adding ethylene, vinyl acetate and an initiator into a reaction device in batches and in sequence, and carrying out sectional polymerization reaction by pulse heating to obtain EVA;
wherein the solvent is added by one or more of adding independently, ethylene and solvent solution, vinyl acetate and solvent solution and initiator and solvent solution;
the raw materials for synthesizing EVA comprise ethylene, vinyl acetate, an initiator and a solvent.
Preferably, the batch sub-sequence is specifically:
firstly adding a certain amount of vinyl acetate, introducing ethylene with a certain pressure for polymerization reaction, heating, then adding a certain amount of vinyl acetate, and continuing the polymerization reaction;
or,
vinyl acetate is added, ethylene with a certain pressure is introduced, and a certain amount of ethylene is introduced after a certain time of polymerization reaction, so that the polymerization reaction is continued.
Preferably, the initiator is added before and/or after the addition of the vinyl acetate before the polymerization reaction takes place and/or before and/or after the addition of the ethylene before the polymerization reaction takes place;
The pulse heating is specifically heating to a certain temperature, cooling after staying for a certain time, heating after staying for a certain time, and sequentially repeating the heating, and controlling the temperature and the stay time.
Preferably, the polymerization comprises free radical solution polymerization;
the initiator comprises one or two of azodiisobutyronitrile, azodiisoheptonitrile, dimethyl azodiisobutyrate, azobis (2-methylbutyronitrile), hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide tert-butyl peroxide, methyl ethyl ketone peroxide, diisobutyryl peroxide, neopentyl peroxyneodecanoate, amyl peroxypivalate, butyl peroxyacetate and dibutyl peroxydicarbonate;
the solvent comprises one or more of n-hexane, petroleum ether, tetrahydrofuran, methanol, ethanol, propanol and the like as a solvent, and preferably one or more of n-hexane, petroleum ether, tetrahydrofuran, methanol and ethanol;
the volume ratio of the total amount of vinyl acetate to the solvent in the reaction device is (1-30): 1, a step of;
the total concentration of the initiator added in the polymerization reaction process is (2.2-9.8) multiplied by 10 -3 mol/L；
The temperature of the polymerization reaction is 45-125 ℃;
the polymerization reaction time is 2-8 hours;
The pressure of the polymerization reaction is 0.5-15 MPa;
the pressure was kept stable during the polymerization.
The invention provides a synthesis method of EVOH, which comprises the following steps:
1) Heating and mixing EVA and methanol, adding a catalyst for reaction, simultaneously adding methanol, keeping the EVA concentration in a reaction system constant, and then adjusting the pH value to precipitate to obtain the EVOH.
Preferably, the ethylene content in the EVA is 15-45mol%;
in the solution obtained by heating and mixing EVA and methanol, the molar concentration of EVA is 5% -35%;
the temperature of the heating and mixing is 50-120 ℃;
the mass ratio of the catalyst to the EVOH is (25-40): 1, a step of;
the catalyst is added for a plurality of times;
the times of the multiple times are 2-4 times;
the catalyst comprises one or more of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution and potassium carbonate solution;
the concentration of the catalyst is 20-100 g/L.
Preferably, the reaction time is 3-10 hours;
the regulator for regulating the pH value comprises one or more of boric acid, oxalic acid, acetic acid and citric acid;
the pH value is 5-8;
the concentration of the regulator is 0.5-1.5 mol/L;
the precipitation mode comprises precipitation in hot water;
The precipitation temperature is 55-95 ℃;
the time for precipitation is 20-80 min;
the EVA comprises EVA synthesized by the synthesis method according to any one of the technical schemes.
The invention provides an EVOH resin, and the gel permeation chromatography curve of the EVOH resin is in a double-peak form. Compared with the prior art, the invention is based on the research that EVOH (ethylene-vinyl alcohol copolymer) has excellent gas barrier property and processability, which depend on chain accumulation, molecular weight, main structure, branching degree and the like of the polymer, so that the barrier property and processability of EVOH depend not only on the content of ethylene in the polymer, but also on the distribution and position of hydroxyl groups, crystallization property of the polymer and the like. Whereas EVOH is prepared by alcoholysis of EVA (ethylene-vinyl acetate copolymer), so the controlled synthesis of EVA has a dominant effect on the performance of EVOH.
The invention provides a regulation and control method and a synthesis method for preparing EVA (ethylene-vinyl acetate copolymer) with a controllable structure, wherein the method is based on the controllable release of initiator free radicals, and realizes regulation and control on EVA structure, molecular weight and the like by regulating and controlling a feeding mode, a solvent effect, pulse heating and a composite initiator according to the relation between the polymerization reaction dynamic characteristics, the concentration of the free radicals, the generation rate and the initiation efficiency and the self-acceleration phenomenon. In particular, the prepared EVA is used for synthesizing EVOH (ethylene-vinyl alcohol copolymer) resin, and Gel Permeation Chromatography (GPC) test shows that EVOH resin with bimodal distribution can be obtained by the regulating method provided by the invention. The method has the characteristics of strong controllability, mild conditions, simple operation and large-scale synthesis prospect. The invention realizes the controllable polymerization of ethylene and vinyl acetate, regulates and controls the polymer structure, the hydroxyl distribution and the like, is beneficial to improving the high molecular weight of the polymer, improving the crystallization behavior (including crystal phase separation) of the polymer, and has important significance for further improving the barrier property and the processing property of EVOH and improving the batch stability of products.
Experimental results show that the EVA with the controllable release of free radicals prepared by the invention can obtain EVOH resin with high molecular weight, particularly bimodal distribution, through alcoholysis reaction.
Drawings
FIG. 1 is a DSC of a different EVOH resin;
FIG. 2 is a graph showing the effect of pressure on the solubility of ethylene in butanol and the reaction system;
FIG. 3 is a graph showing solubility parameters of different solvents;
FIG. 4 is a graph showing the effect of reaction temperature/pressure on monomer reactivity ratios;
FIG. 5 is a graph showing the effect of pressure and temperature on ethylene solubility;
FIG. 6 is a polymerization reaction profile in the present invention;
FIG. 7 is a nuclear magnetic resonance spectrum of EVA prepared in example 1 of the present invention;
FIG. 8 is a nuclear magnetic resonance spectrum of EVOH prepared in example 1 of the present invention;
FIG. 9 is a GPC chart of EVOH resin prepared in example 1 of the present invention;
FIG. 10 is a GPC chart of a bimodal distribution EVOH resin prepared in example 2 of the present invention;
FIG. 11 is a GPC chart of a bimodal distribution EVOH resin prepared in example 3 of the present invention;
FIG. 12 shows the characterization and calculation method of the branching degree of the EVOH resin prepared in accordance with the present invention 13 C NMR）；
FIG. 13 is an external view of an EVOH resin and film prepared according to the present invention.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention and are not limiting of the invention claims.
All the raw materials of the present invention are not particularly limited in their sources, and may be purchased on the market or prepared according to conventional methods well known to those skilled in the art.
The purity of all the raw materials of the invention is not particularly limited, and the invention preferably adopts industrial raw materials or EVA and EVOH with conventional purity requirements in the field of preparation.
All raw materials and processes of the invention, the brands or abbreviations of which belong to the conventional brands or abbreviations in the field of the related application are clear and definite, and according to the brands, abbreviations and the corresponding application, the raw materials and processes can be purchased from the market or prepared by the conventional method or realized by adopting the corresponding equipment.
The invention provides an EVOH resin, and the gel permeation chromatography curve of the EVOH resin is in a double-peak form.
In the present invention, the weight average molecular weight of the first peak in the double peaks is preferably 6.92 to 8.70kg/mol, more preferably 7.0 to 8.50kg/mol, still more preferably 7.2 to 8.3kg/mol, and still more preferably 7.5 to 8.0 kg/mol.
In the present invention, the weight average molecular weight of the second peak in the double peaks is preferably 4.38 to 7.15kg/mol, more preferably 4.5 to 7.0kg/mol, more preferably 4.8 to 6.8kg/mol, more preferably 5.0 to 6.5kg/mol, more preferably 5.3 to 6.2kg/mol, more preferably 5.5 to 6.0kg/mol.
In the present invention, the molecular weight distribution PDI (gel permeation chromatography) of the EVOH resin is preferably 3.6 to 6.8, more preferably 3.9 to 6.5, more preferably 4.2 to 6.3, more preferably 4.5 to 6.0, more preferably 4.8 to 5.7, more preferably 5.0 to 5.5.
In the present invention, the EVOH resin has a branching degree of 1000 CH/1000 CH 2 The number of mid-branched chains is preferably 50 or less, more preferably 40 or less, and still more preferably 30 or less.
In the present invention, the EVOH resin backbone structure is composed of ethylene and vinyl acetate by random copolymerization.
Referring to FIG. 1, FIG. 1 is a DSC chart of a different EVOH resin.
The invention provides a regulation and control method for synthesizing EVA, which comprises the following steps:
a) Setting a feeding mode and a feeding sequence of ethylene and vinyl acetate based on the initiation speed of an initiator on the ethylene and the vinyl acetate;
b) Setting the selection, the number and the addition mode of the initiator based on the automatic acceleration effect of the free radical polymerization reaction;
c) Setting the type of solvent and/or the number of solvents based on the chain transfer constant of the solvent, the solubility of ethylene in the solvent, the solubility of vinyl acetate in the solvent and the distribution coefficient of ethylene in the vinyl acetate and the solvent, so as to regulate and control the structure and/or the molecular weight of the synthesized EVA;
When the number of the solvents is more than or equal to 2, the step c) further comprises a distribution coefficient of the vinyl acetate in the mixed solvent;
d) Setting a heating mode of the synthesis reaction based on the relation between the free radical generated by the initiator and the temperature;
the above steps of the regulation method are not in sequence.
The invention sets the feeding mode and the feeding sequence of the ethylene and the vinyl acetate based on the initiation speed of the initiator on the ethylene and the vinyl acetate. Specifically, a certain amount of vinyl acetate is added first, ethylene with a certain pressure is introduced to carry out polymerization reaction, and a certain amount of vinyl acetate is added after heating, so that the polymerization reaction is continued. Or adding vinyl acetate, introducing ethylene with a certain pressure, polymerizing for a certain time, introducing a certain amount of ethylene, and continuing the polymerization.
The invention sets the selection, the number and the addition mode of the initiator based on the automatic acceleration effect of the free radical polymerization reaction.
In the present invention, the choice of the initiator is preferably a specific kind or a specific choice of the directing agent.
The invention sets the solvent type and/or the number of solvents based on the chain transfer constant of the solvent, the solubility of the ethylene in the solvent, the solubility of the vinyl acetate in the solvent and the distribution coefficient of the ethylene in the vinyl acetate and the solvent, thereby regulating and controlling the structure and/or the molecular weight of the synthesized EVA.
The solubility parameters of the different solvents are different (solvent effect 1)
When the number of the solvents is more than or equal to 2, the step c) further comprises a distribution coefficient of the vinyl acetate in the mixed solvent. Partition ratio in Mixed solvent (solvent Effect 2)
Wherein the distribution coefficient =。
In the present invention, the kind of the solvent preferably means a specific choice of the solvent.
In the present invention, when the number of solvents is 2 or more, it is preferable to refer to a mixed solvent of two solvents, and therefore, in this case, the partition coefficient of vinyl acetate in the mixed solvent is also included in the step c).
In the present invention, the solubility of the solvent is also related to the pressure of the reaction;
referring to fig. 2, fig. 2 is an effect of pressure on solubility of ethylene in butanol and the reaction system.
Referring to fig. 3, fig. 3 is a graph of solubility parameters for different solvents.
In the present invention, the control method preferably further comprises setting values of the reaction temperature and the pressure based on the influence relationship of the reaction and the pressure on the solubility.
Referring to fig. 4, fig. 4 is an effect of reaction temperature/pressure on monomer reactivity ratio.
Referring to fig. 5, fig. 5 is the effect of pressure and temperature on ethylene solubility.
The invention sets the heating mode of the synthesis reaction based on the relation between the free radical generated by the initiator and the temperature. Specifically, a pulse heating may be employed. In the invention, the pulse heating can be heating to a certain temperature, cooling after a certain time, heating after a certain time, and sequentially repeating the heating, and controlling the temperature and the residence time.
Referring to fig. 6, fig. 6 is a polymerization reaction characteristic in the present invention.
In the invention, the regulation method is provided, and the regulation method is in a stepwise form for convenience in description and illustration, so that no sequencing is adopted.
The invention provides an EVA synthesis method based on the regulation and control method, which comprises the following steps:
1') adding ethylene, vinyl acetate and an initiator into a reaction device in batches and in sequence, and carrying out sectional polymerization reaction by pulse heating to obtain EVA;
wherein the solvent is added by one or more of adding independently, ethylene and solvent solution, vinyl acetate and solvent solution and initiator and solvent solution;
the raw materials for synthesizing EVA comprise ethylene, vinyl acetate, an initiator and a solvent.
In the present invention, the synthetic raw material is an industrial grade raw material.
In the present invention, the batch sub-order may specifically be:
adding a certain amount of vinyl acetate, introducing ethylene with a certain pressure for polymerization reaction, heating, adding a certain amount of vinyl acetate, and continuing the polymerization reaction. Or adding vinyl acetate, introducing ethylene with a certain pressure, polymerizing for a certain time, introducing a certain amount of ethylene, and continuing the polymerization.
In the present invention, the initiator is added before and/or after the vinyl acetate is added before the polymerization reaction occurs.
And/or the number of the groups of groups,
before and/or after the addition of ethylene, the initiator is added before and/or after the polymerization reaction takes place.
In the invention, the pulse heating can be concretely heating to a certain temperature, cooling after a certain time of stay, heating after a certain time of stay, and sequentially repeating the heating, and controlling the temperature and the stay time.
In the present invention, the polymerization preferably includes radical solution polymerization.
In the present invention, the initiator preferably includes one or two of azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, azobis (2-methylbutyronitrile), hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide tertiary butyl ester, methyl ethyl ketone peroxide, diisobutyryl peroxide, amyl neodecanoate peroxide, amyl pivalate peroxide, butyl acetate peroxide and dibutyl peroxydicarbonate, more preferably azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, azobis (2-methylbutyronitrile), hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide tertiary butyl ester, methyl ethyl ketone peroxide, diisobutyryl peroxide, amyl neodecanoate peroxide, amyl pivalate peroxide, butyl acetate peroxide or dibutyl peroxydicarbonate.
In the present invention, the solvent preferably includes one or more of n-hexane, petroleum ether, tetrahydrofuran, methanol, ethanol, and propanol, more preferably n-hexane, petroleum ether, tetrahydrofuran, methanol, ethanol, or propanol.
In the present invention, the volume ratio of the total amount of vinyl acetate to the solvent in the reaction device is preferably (1 to 30): 1, more preferably (5 to 25): 1, more preferably (10 to 20): 1.
in the invention, the total concentration of the initiator added in the polymerization reaction process is preferably (2.2-9.8) x 10 - 3 The mol/L is more preferably (3.2 to 8.8). Times.10 -3 more preferably (4.2 to 7.8). Times.10 mol/L -3 more preferably (5.2 to 6.8). Times.10 mol/L -3 mol/L。
In the present invention, the polymerization reaction temperature is preferably 45 to 125 ℃, more preferably 55 to 115 ℃, more preferably 65 to 105 ℃, more preferably 75 to 95 ℃.
In the present invention, the polymerization reaction time is preferably 2 to 8 hours, more preferably 3 to 7 hours, and still more preferably 4 to 6 hours.
In the present invention, the reaction pressure is preferably derived from the pressure of the mixture of ethylene gas and protective gas or the pressure of ethylene gas. Specifically, the reaction pressure is preferably 0.5 to 15MPa, more preferably 2.5 to 13MPa, and even more preferably 5 to 10MPa.
In the present invention, the protective gas preferably includes nitrogen and/or an inert gas, more preferably nitrogen or an inert gas, and particularly may be nitrogen or argon.
In the present invention, the pressure is preferably kept stable during the polymerization reaction, more preferably kept constant.
In the present invention, the ethylene content in the EVA is preferably 15 to 45mol%, more preferably 20 to 40mol%, and still more preferably 25 to 35mol%.
The invention has the advantages that the integral technical scheme is complete and refined, the structure and the performance of the final product are better ensured, the steps provide a regulating and controlling method and a synthesizing method of the synthesized EVA with controllable release of free radicals, and the method can be concretely as follows:
ethylene and vinyl acetate are used as raw materials to prepare EVA in a free radical solution polymerization system, and the structure of the EVA is regulated and controlled through the controllable release of free radicals based on the relation between the dynamic characteristics of polymerization reaction and the concentration, the generation rate and the initiation efficiency of the free radicals and the self-acceleration phenomenon, and the EVA is used for preparing the EVOH.
Wherein the ethylene content in EVA is 15-45 mol%.
The structure, in particular the polymerization rate, the polymer molecular weight and the branching degree are controllable, in particular it is meant that EVOH with a bimodal distribution can be prepared. The raw materials of the invention are industrial grade raw materials.
The radical solution polymerization is carried out by using one or two of azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azodiisobutyrate, azobis (2-methylbutyronitrile), hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, diisobutyryl peroxide, amyl peroxyneodecanoate, amyl peroxypivalate, butyl peroxyacetate or dibutyl peroxydicarbonate as an initiator, preferably one or two of azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azodiisobutyrate, hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, diisobutyryl peroxide, amyl peroxyneodecanoate, amyl peroxypivalate, butyl peroxyacetate, more preferably one or two of azobisisobutyronitrile, azobisisoheptonitrile, hydrogen peroxide, ammonium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide, peroxyneodecanoate, amyl peroxypivalate, butyl peroxypivalate and butyl peroxypivalate.
One or more of n-hexane, petroleum ether, tetrahydrofuran, methanol, ethanol, propanol and the like is used as a solvent, preferably one or more of n-hexane, petroleum ether, tetrahydrofuran, methanol and ethanol, more preferably one or more of n-hexane, tetrahydrofuran, methanol and ethanol.
Solution polymerization was initiated in a 500ml stainless steel autoclave with a tetrafluoro liner to give EVA. Before the reaction, after the tightness of the reaction kettle is checked, the reaction kettle is heated to 100 ℃ for 30min, nitrogen is adopted for 3-5 times of replacement, and finally ethylene gas is adopted for 3-5 times of replacement. Cooling to below 40deg.C, and adding raw materials.
The invention is initiated by free radical, EVA is obtained by solution polymerization, and the EVA is realized by regulating and controlling a feeding mode, a solvent effect and pulse heating, and the invention specifically comprises the following steps:
(1) According to different initiating speeds of the initiator on ethylene and vinyl acetate, the raw materials are added into a reaction kettle in batches according to different sequences, and the method specifically comprises the following steps: firstly adding a certain amount of vinyl acetate, introducing ethylene under a certain pressure, heating, and then (continuously) adding a certain amount of vinyl acetate; or adding vinyl acetate, introducing ethylene with a certain pressure, reacting for a certain time, and introducing a certain amount of ethylene.
(2) The initiator is added into the reaction system in batches and in parts according to the automatic acceleration effect of the free radical polymerization reaction.
(3) According to different chain transfer constants in different solvents and different solubilities and distribution coefficients of ethylene and vinyl acetate in different solvents, a solvent or mixed solvent system is adopted to regulate and control the structure and molecular weight of the polymer.
(4) According to the dependency of the free radical generated by the initiator on the temperature, pulse heating, specifically heating to a certain temperature, cooling after staying for a certain time, heating after staying for a certain time, and sequentially repeating, and controlling the temperature and the stay time.
Controlling the volume ratio of the total amount of vinyl acetate to the solvent in the reaction system to be 1-30/1, preferably 3-28/1, and more preferably 5-25/1; the total amount of liquid added into the reaction kettle is 80-150 ml, preferably 90-140 ml, more preferably 95-135 ml; controlling the total concentration of the initiator to be 2.2-9.8x10 -3 mol/L, preferably 2.5 to 9.5X10 -3 The mol/L is more preferably 2.8 to 9.0X10 -3 mol/L; the polymerization reaction temperature is 45-125 ℃, preferably 50-120 ℃, more preferably 55-115 ℃; the reaction time is 2-8 hours, preferably 2.5-7.5 hours, more preferably 2.5-7.5 hours; the reaction pressure is 0.5 to 15MPa, preferably 1 to 13.5MPa, more preferably 2 to 12.5MPa. The pressure was kept constant during the reaction. And after the reaction is finished, drying the obtained EVA in a vacuum oven at 65 ℃ for later use.
The invention also provides a synthesis method of the EVOH, which comprises the following steps:
1) Heating and mixing EVA and methanol, adding a catalyst for reaction, simultaneously adding methanol, keeping the EVA concentration in a reaction system constant, and then adjusting the pH value to precipitate to obtain the EVOH.
In the present invention, the synthetic raw material is an industrial grade raw material.
In the present invention, the EVA preferably includes EVA synthesized by the synthesis method according to any one of the above technical schemes.
In the present invention, the ethylene content in the EVA is preferably 15 to 45mol%, more preferably 20 to 40mol%, and still more preferably 25 to 35mol%.
In the invention, in the solution obtained by heating and mixing EVA and methanol, the molar concentration of EVA is preferably 5% -35%, more preferably 10% -30%, and even more preferably 15% -20%.
In the present invention, the temperature of the heating and mixing is preferably 50 to 120 ℃, more preferably 60 to 110 ℃, more preferably 70 to 100 ℃, more preferably 80 to 90 ℃.
In the present invention, the mass ratio of the catalyst to the EVOH is preferably (25 to 40): 1, more preferably (28 to 38): 1, more preferably (30 to 35): 1.
in the present invention, the catalyst is preferably added in a plurality of times. Specifically, the number of times of the plurality of times is preferably 2 to 4 times, more preferably 3 to 4 times.
In the present invention, the catalyst preferably includes one or more of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution and potassium carbonate solution, more preferably sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution or potassium carbonate solution.
In the invention, the concentration of the catalyst is preferably 20-100 g/L, more preferably 30-90 g/L, more preferably 40-80 g/L, more preferably 50-70 g/L.
In the invention, the reaction time is preferably 3 to 10 hours, more preferably 4 to 9 hours, more preferably 5 to 8 hours, and more preferably 6 to 7 hours.
In the present invention, the pH adjusting agent preferably includes one or more of boric acid, oxalic acid, acetic acid and citric acid, more preferably boric acid, oxalic acid, acetic acid or citric acid.
In the present invention, the pH is preferably 5 to 8, more preferably 5.5 to 7.5, and even more preferably 6 to 7.
In the present invention, the concentration of the regulator is preferably 0.5 to 1.5mol/L, more preferably 0.7 to 1.3mol/L, and still more preferably 0.9 to 1.1mol/L.
In the present invention, the precipitation means preferably includes precipitation in hot water.
In the present invention, the temperature of the precipitation is preferably 55 to 95 ℃, more preferably 60 to 90 ℃, more preferably 65 to 85 ℃, more preferably 70 to 80 ℃.
In the invention, the time of precipitation is preferably 20 to 80min, more preferably 30 to 70min, and even more preferably 40 to 60min.
The invention has the advantages of complete and refined integral technical scheme, better ensuring the structure and performance of the final product, providing the application of EVA with controllable release of free radical in EVOH synthesis, and specifically comprising the following steps:
Dissolving EVA in methanol, controlling the EVA concentration to be 5-35%, setting the heating temperature to be 50-120 ℃, slowly adding 20-60 ml of catalyst into a reaction system in 2-4 equal parts after the reaction temperature is stable, and simultaneously, continuously adding methanol by using a constant-pressure dropping funnel to keep the EVA concentration of the system unchanged; the catalyst is a solution of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like, and the concentration is 20-100 g/L. After 3-10 hours of reaction, the pH value of the system is regulated to 5-8 by adopting solutions of boric acid, oxalic acid, acetic acid, citric acid (the concentration is 0.5-1.5 mol/L) and the like, the product is transferred into 1000ml of deionized water to be separated out, filtered, treated with hot water at 50-100 ℃ for 10-90 minutes and dried at 120 ℃.
Specifically, EVA is dissolved in methanol, and the EVA concentration is controlled to be 5-35%, preferably 10-30%, more preferably 12-28%; setting the heating temperature to be 50-120 ℃, preferably 55-115 ℃, and more preferably 60-110 ℃; after the reaction temperature is stable, slowly adding 2-4 equal parts of 20-60 ml (preferably 25-55 ml, more preferably 30-50 ml) of catalyst into the reaction system, and simultaneously, continuously adding methanol by using a constant-pressure dropping funnel to keep the EVA concentration of the system unchanged; the catalyst is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and other solutions, preferably sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate solutions, more preferably sodium hydroxide, potassium hydroxide and sodium carbonate solutions, and the catalyst concentration is 20-100 g/L, preferably 25-95 g/L, more preferably 30-90 g/L. The reaction is carried out for 3-10 hours, preferably 3.5-9.5 hours, more preferably 3.5-9.5 hours; the pH of the system is adjusted to 5-8, preferably 5.5-7.5, more preferably 6-7 by adopting solutions such as boric acid, oxalic acid, acetic acid, citric acid (the concentration is 0.5-1.5 mol/L, the concentration is preferably 0.8-1.3 mol/L, more preferably 1.0-1.2 mol/L) and the like; the solution is preferably boric acid, oxalic acid, acetic acid or citric acid solution, and more preferably boric acid, oxalic acid or acetic acid solution; transferring the product to 1000ml of deionized water for precipitation, filtering, treating with hot water at 50-100 ℃ for 10-90 min, preferably at 55-95 ℃, more preferably at 60-90 ℃, preferably at 20-80 min, more preferably at 25-75 min, and finally drying the obtained product at 120 ℃.
The invention provides a regulating and controlling method and a synthesizing method of synthetic EVA with controllable release of free radicals, and an EVOH resin and a synthesizing method thereof. The invention is based on the controllable release of initiator free radicals, and realizes the regulation and control of EVA structure, molecular weight and the like by regulating and controlling the feeding mode, the solvent effect, the pulse heating and the composite initiator according to the relation between the polymerization reaction dynamics characteristic and the free radical concentration, the generation rate and the initiation efficiency and the self-acceleration phenomenon. In particular, the prepared EVA is used for synthesizing EVOH (ethylene-vinyl alcohol copolymer) resin, and Gel Permeation Chromatography (GPC) test shows that EVOH resin with bimodal distribution can be obtained by the regulating method provided by the invention. The method has the characteristics of strong controllability, mild conditions, simple operation and large-scale synthesis prospect. The invention realizes the controllable polymerization of ethylene and vinyl acetate, regulates and controls the polymer structure, the hydroxyl distribution and the like, is beneficial to improving the high molecular weight of the polymer, improving the crystallization behavior (including crystal phase separation) of the polymer, and has important significance for further improving the barrier property and the processing property of EVOH and improving the batch stability of products.
Experimental results show that the EVA with the controllable release of free radicals prepared by the invention can obtain EVOH resin with high molecular weight, particularly bimodal distribution, through alcoholysis reaction.
In order to further illustrate the present invention, the following describes in detail a regulation and control method for synthesizing EVA, a synthesis method for synthesizing EVOH resin and a synthesis method thereof, which are provided by the present invention, but it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given only for further illustrating the features and advantages of the present invention, and not limiting the claims of the present invention, and the scope of protection of the present invention is not limited to the following examples.
Example 1
The tightness of 500ml stainless steel autoclave with tetrafluoro liner was checked, and the autoclave was heated to 100℃for 30 minutes, replaced with nitrogen 3 times and then with ethylene gas 3 times. Cooling the reaction kettle to below 40 ℃, adding 35ml of ethyl acetate, adding an initiator azodiisobutyronitrile and 10ml of ethanol into the reaction kettle, stirring while charging ethylene at 4.0MPa, heating to 75 ℃, continuously charging ethylene to keep the pressure of the reaction system stable, reacting for 1h, closing ethylene, mixing 40ml of vinyl acetate, 20ml of tetrahydrofuran and methyl ethyl ketone peroxide, adding the mixture into the reaction kettle through a high-pressure pump, and continuing to react for 3h (controlling the concentration of azodiisobutyronitrile and methyl ethyl ketone peroxide in the reaction system to be 2.8X10 respectively in the feeding process) -3 mol/L and 4.0X10 -3 mol/L). After the reaction, the reaction mixture was cooled to room temperature, the pressure was released, and the product was transferred to a vacuum oven and dried at 65℃to give EVA having an ethylene content of 32% (NMR, mol) and a nuclear magnetic resonance hydrogen spectrum as shown in FIG. 7.
Referring to fig. 7, fig. 7 is a nuclear magnetic hydrogen spectrum of EVA prepared in example 1 of the present invention.
Dissolving EVA in 200ml of methanol (the EVA concentration is 25 wt%), heating to 85 ℃, after the reaction temperature is stable, dividing 20ml of NaOH solution (the concentration is 65 g/L) into 4 equal parts, slowly adding the solution into a reaction system every 30min in sequence, and simultaneously, continuously adding methanol by using a constant-pressure dropping funnel, so as to keep the EVA concentration of the system unchanged; after the reaction is carried out for 6 hours, 1.0mol/L oxalic acid solution is adopted to adjust the pH value of the system to 6; then transferring the product to 1000ml deionized water for precipitation, filtering, treating the product with hot water at 80 ℃ for 70min, and drying the obtained product at 120 ℃ to obtain the EVOH resin. The Mn molecular weight was 13.2kg/mol, and the PDI distribution was 1.17, as shown in FIG. 8 and FIG. 9.
Referring to FIG. 8, FIG. 8 is a nuclear magnetic resonance hydrogen spectrum of EVOH prepared in example 1 of the present invention.
Referring to fig. 9, fig. 9 is a GPC diagram of the EVOH resin prepared in example 1 of the present invention.
Example 2
Check 500ml of non-fluorinated linerThe air tightness of the stainless steel high-pressure reaction kettle is improved to 100 ℃ for 30min, nitrogen is adopted for 5 times of replacement, and ethylene gas is adopted for 5 times of replacement. Cooling the reaction kettle to below 40 ℃, adding 80ml of ethyl acetate, adding an initiator azodiisobutyronitrile and 10ml of ethanol into the reaction kettle, stirring while charging 3.5MPa of ethylene, heating to 75 ℃, continuously charging ethylene to keep the pressure of the reaction system stable, reacting for 2 hours, closing ethylene, mixing hydrogen peroxide and 20ml of n-hexane, adding the mixture into the reaction kettle through a high-pressure pump, then continuously maintaining the pressure of the reaction system through ethylene, and continuously reacting for 3 hours (controlling the concentration of azodiisobutyronitrile and the concentration of hydrogen peroxide in the reaction system to be 3.6X10 respectively in the feeding process) -3 mol/L and 3.6X10 -3 mol/L). After the reaction was completed, the reaction mixture was cooled to room temperature, the pressure was released, and the product was transferred to a vacuum oven and dried at 65℃to give EVA having an ethylene content of 28% (NMR, mol).
EVA was dissolved in 200ml of methanol (EVA concentration 20 wt.%) and the temperature was raised to 75℃and after the reaction temperature had stabilized, 40ml of K was added 2 CO 3 The solution (the concentration is 25 g/L) is divided into 4 equal parts, and is slowly added into a reaction system at intervals of 30min in sequence, and meanwhile, methanol is continuously added by a constant-pressure dropping funnel, so that the EVA concentration of the system is kept unchanged; after 4h of reaction, adopting acetic acid solution with the concentration of 1.0mol/L to adjust the pH value of the system to 7; the product was then transferred to 1000ml deionized water to precipitate, filtered and treated with hot water at 60℃for 30min, and the resulting product was dried at 120℃to give a bimodal distribution of EVOH resin, as shown in FIG. 10.
Referring to FIG. 10, FIG. 10 is a GPC chart of a bimodal distribution EVOH resin prepared in example 2 of the present invention.
Example 3
The tightness of 500ml stainless steel autoclave with tetrafluoro liner was checked, and the autoclave was heated to 100℃for 30 minutes, replaced with nitrogen for 4 times and with ethylene gas for 4 times. Cooling the reaction kettle to below 40deg.C, mixing 10ml n-hexane, 10ml ethanol and initiator azodiisoheptonitrile and benzoyl peroxide, and adding into the reaction kettle (controlling the concentrations of azodiisoheptonitrile and benzoyl peroxide in the reaction system to be 5.5X10 respectively) -3 mol/L and 2.5X10 -3 mol/L), after charging ethylene at 3.0MPa,heating to 80 ℃ and keeping the pressure stable for 30min, closing ethylene, adding 115ml of ethyl acetate into a reaction kettle through a high-pressure pump, introducing ethylene to keep the pressure stable, stirring and reacting for 4h, cooling to room temperature, releasing the pressure, transferring the product to a vacuum oven, and drying at 65 ℃ to obtain EVA with the ethylene content of 17% (NMR, mol).
EVA was dissolved in 200ml of methanol (EVA concentration 20 wt.%) and heated to 90℃until the reaction temperature was stable, 30ml of Na was added 2 CO 3 The solution (the concentration is 50 g/L) is divided into 3 equal parts, and is slowly added into a reaction system at intervals of 30min in sequence, and meanwhile, methanol is continuously added by a constant-pressure dropping funnel, so that the EVA concentration of the system is kept unchanged; after the reaction is carried out for 6 hours, 1.0mol/L oxalic acid solution is adopted to adjust the pH value of the system to 6; the product was then transferred to 1000ml deionized water to precipitate, filtered, treated with hot water at 90℃for 60min, and the resulting product dried at 120℃to give a bimodal distribution of EVOH resin, as shown in FIG. 11.
Referring to FIG. 11, FIG. 11 is a GPC chart of a bimodal distribution EVOH resin prepared in example 3 according to the present invention.
Example 4
The tightness of 500ml stainless steel autoclave with tetrafluoro liner was checked, and the autoclave was heated to 100℃for 30 minutes, replaced with nitrogen 5 times and then with ethylene gas 5 times. After the reaction kettle is cooled to below 40 ℃, 90ml of ethyl acetate is added, then an initiator azodiisobutyronitrile, 15ml of methanol and 10ml of tetrahydrofuran are mixed and added into the reaction kettle, 3.2MPa of ethylene is filled while stirring, the temperature is raised to 70 ℃ for reaction for 0.5h, the temperature is reduced to 50 ℃ and kept for 0.5h, then the temperature is raised to 70 ℃ and kept for 1.5h, and then the initiator azodiisobutyronitrile and 10ml of methanol are mixed (the concentration of the azodiisobutyronitrile added for two times is respectively 4.0X10) -3 mol/L and 1.5X10 -3 mol/L), adding the mixture into a reaction kettle through a high-pressure pump, then cooling to 50 ℃, keeping the temperature for 0.5h, then heating to 70 ℃, introducing ethylene to keep the pressure of a reaction system constant, and continuing the reaction for 2h. After the reaction was completed, the reaction mixture was cooled to room temperature, the pressure was released, and the product was transferred to a vacuum oven and dried at 65℃to give EVA having an ethylene content of 22% (NMR, mol).
Dissolving EVA in 200ml of methanol (the EVA concentration is 15 wt%), heating to 75 ℃, after the reaction temperature is stable, dividing 40ml of KOH solution (the concentration is 40 g/L) into 4 equal parts, slowly adding the solution into a reaction system every 30min in sequence, and simultaneously, continuously adding methanol by using a constant-pressure dropping funnel, so as to keep the EVA concentration of the system unchanged; after the reaction is carried out for 6 hours, acetic acid solution with the concentration of 1.1mol/L is adopted to adjust the pH value of the system to 7; then transferring the product to 1000ml deionized water for precipitation, filtering, treating the product with hot water at 90 ℃ for 30min, and drying the obtained product at 120 ℃ to obtain the EVOH resin. The molecular weight Mn was 12.09 kg/mol and the distribution PDI was 6.76.
Example 5
The tightness of 500ml stainless steel autoclave with tetrafluoro liner was checked, and the autoclave was heated to 100℃for 30 minutes, replaced with nitrogen 3 times and then with ethylene gas 3 times. After the reaction kettle is cooled to below 40 ℃, 50ml of ethyl acetate is firstly added, then an initiator hydrogen peroxide and 10ml of ethanol are mixed and added into the reaction kettle, 2.0MPa of ethylene is filled while stirring, after the temperature is raised to 75 ℃, the reaction is carried out for 0.5h, the temperature is reduced to 50 ℃ and maintained for 0.5h, then 40ml of vinyl acetate, 10ml of ethanol and hydrogen peroxide are mixed and then added into the reaction kettle by a high-pressure pump (the concentration of the hydrogen peroxide added for two times is 3.5 multiplied by 10 respectively) -3 mol/L and 3.5X10 -3 mol/L), ethylene is introduced to adjust the reaction pressure to 4.0MPa, the temperature is raised to 75 ℃ and the pressure is kept stable, and the reaction is continued for 3 hours. After the reaction, cooling to room temperature, releasing the pressure, transferring the product to a vacuum oven, and drying at 65 ℃ to obtain EVA with the ethylene content of 35% (NMR, mol).
Dissolving EVA in 200ml of methanol (the EVA concentration is 25 wt%), heating to 80 ℃, after the reaction temperature is stable, dividing 40ml of NaOH solution (the concentration is 25 g/L) into 4 equal parts, slowly adding the solution into a reaction system every 30min in sequence, and simultaneously, continuously adding methanol by using a constant-pressure dropping funnel, so as to keep the EVA concentration of the system unchanged; after 4 hours of reaction, adopting 1.2mol/L boric acid solution to adjust the pH value of the system to 6; then transferring the product to 1000ml deionized water for precipitation, filtering, treating the product with hot water at 80 ℃ for 40min, and drying the obtained product at 120 ℃ to obtain the EVOH resin. The molecular weight Mn was 10.72 kg/mol and the distribution PDI was 6.53.
Example 6
500ml of the tape was inspected for tetrafluoroThe air tightness of the stainless steel high-pressure reaction kettle with the lining is improved to 100 ℃ for 30min, nitrogen is adopted for replacement for 5 times, and ethylene gas is adopted for replacement for 5 times. After the reaction kettle is cooled to below 40 ℃, 50ml of ethyl acetate is added, and then initiator azobisisobutyronitrile and hydrogen peroxide are mixed with 10ml of methanol and added into the reaction kettle (the concentration of the azobisisobutyronitrile and the hydrogen peroxide are controlled to be 1.5 multiplied by 10 respectively) -3 mol/L and 3.0X10 -3 mol/L), 2.0MPa of ethylene is filled while stirring, after the temperature is raised to 80 ℃, the ethylene is continuously filled to keep the pressure of the reaction system stable, after 2 hours of reaction, the ethylene is closed, 40ml of vinyl acetate, 10ml of ethanol and hydrogen peroxide are mixed with azobisisobutyronitrile (the concentration of the azobisisobutyronitrile and the concentration of the hydrogen peroxide are controlled to be 1.5X10 respectively) -3 mol/L and 3.0X10 -3 mol/L), adding the mixture into a reaction kettle through a high-pressure pump, then introducing ethylene to adjust the reaction pressure to 3.0MPa, keeping the reaction stable, and continuing the reaction for 2 hours. After the reaction was completed, the reaction mixture was cooled to room temperature, the pressure was released, and the product was transferred to a vacuum oven and dried at 65℃to give EVA having an ethylene content of 23% (NMR, mol).
Dissolving EVA in 200ml of methanol (the EVA concentration is 15 wt%), heating to 70 ℃, after the reaction temperature is stable, dividing 20ml of NaOH solution (the concentration is 35 g/L) into 4 equal parts, slowly adding the solution into a reaction system every 30min in sequence, and simultaneously, continuously adding methanol by using a constant-pressure dropping funnel, so as to keep the EVA concentration of the system unchanged; after 8h of reaction, adopting 1.0mol/L boric acid solution to adjust the pH value of the system to 6; then transferring the product to 1000ml deionized water for precipitation, filtering, treating the product with hot water at 85 ℃ for 60min, and drying the obtained product at 120 ℃ to obtain the EVOH resin. The molecular weight Mn is 14.51kg/mol and the distribution PDI is 5.90.
The EVOH resin prepared in example 6 of the present invention was characterized and calculated.
Referring to FIG. 12, FIG. 12 shows the characterization and calculation method of the branching degree of the EVOH resin prepared in accordance with the present invention 6 13 C NMR）。
Referring to fig. 13, fig. 13 is an external view of the EVOH resin and film prepared according to the present invention.
The above detailed description of a method for regulating and synthesizing a synthetic EVA with controlled release of free radicals, an EVOH resin and a method for synthesizing the same, provided by the present invention, applies specific examples herein to illustrate the principles and embodiments of the present invention, the above examples are provided only to assist in understanding the methods of the present invention and their core ideas, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems, and performing any incorporated methods. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims. The scope of the patent protection is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Claims (10)
1. An EVOH resin, characterized in that the gel permeation chromatography curve of the EVOH resin is bimodal;
the weight average molecular weight of the first peak in the double peaks is 6.92-8.70 kg/mol;
the weight average molecular weight of the second peak in the double peaks is 4.38-7.15 kg/mol;
the EVOH resin is prepared from EVA prepared by free radical solution polymerization;
the ethylene content in the EVA is 15-45mol%;
the synthetic method of the EVOH resin comprises the following steps:
1) Heating and mixing EVA and methanol, adding a catalyst for reaction, simultaneously adding methanol, keeping the EVA concentration in a reaction system constant, and then adjusting the pH value to obtain EVOH after precipitation;
the raw materials of the synthetic EVA comprise ethylene, vinyl acetate, an initiator and a solvent;
the EVA synthesis method comprises the following steps:
1') adding ethylene, vinyl acetate and an initiator into a reaction device in batches and in sequence, and carrying out sectional polymerization reaction by pulse heating to obtain EVA;
the polymerization is free radical solution polymerization;
the batch sub-sequence is specifically as follows:
firstly adding vinyl acetate, then introducing ethylene with a certain pressure, and after a certain period of polymerization, introducing a certain amount of ethylene, and continuing the polymerization;
Wherein the solvent is added by one or more of adding independently, ethylene and solvent solution, vinyl acetate and solvent solution and initiator and solvent solution;
the temperature of the polymerization reaction is 45-125 ℃;
the pressure of the polymerization reaction is 0.5-15 MPa.
2. The EVOH resin according to claim 1, wherein the EVOH resin has a molecular weight distribution PDI of 3.6 to 6.8;
the branching degree of the EVOH resin is 1000 CH/1000 CH 2 And 50 or less mid-branched chains.
3. EVOH resin according to claim 1, characterized in that the initiator is added before and/or after the addition of vinyl acetate before the polymerization reaction takes place and/or before and/or after the addition of ethylene before the polymerization reaction takes place.
4. The EVOH resin according to claim 1, wherein the pulse heating is specifically heating to a certain temperature, cooling after a certain residence time, heating after a certain residence time, and sequentially repeating the heating, controlling the temperature and residence time.
5. The EVOH resin according to claim 1, wherein the initiator comprises one or two of azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, azobis (2-methylbutyronitrile), hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, t-butyl benzoyl peroxide, methyl ethyl ketone peroxide, diisobutyryl peroxide, amyl neodecanoate peroxide, amyl pivalate peroxide, butyl acetate peroxide, and dibutyl peroxydicarbonate.
6. The EVOH resin according to claim 1, wherein the solvent comprises one or more of n-hexane, petroleum ether, tetrahydrofuran, methanol, ethanol, and propanol;
the volume ratio of the total amount of vinyl acetate to the solvent in the reaction device is (1-30): 1.
7. the EVOH resin of claim 1, wherein the total concentration of initiator added during the polymerization reaction is (2.2-9.8). Times.10 -3 mol/L；
The polymerization reaction time is 2-8 hours;
the pressure was kept stable during the polymerization.
8. The EVOH resin according to claim 1, wherein the molar concentration of EVA in the solution of EVA and methanol after heating and mixing is 5% to 35%;
the temperature of the heating and mixing is 50-120 ℃;
the mass ratio of the catalyst to the EVOH is (25-40): 1.
9. the EVOH resin according to claim 1, wherein the addition catalyst is added in multiple times;
the times of the multiple times are 2-4 times;
the catalyst comprises one or more of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution and potassium carbonate solution;
the concentration of the catalyst is 20-100 g/L.
10. The EVOH resin according to claim 1, wherein the reaction time in step 1) is 3 to 10 hours;
The regulator for regulating the pH value comprises one or more of boric acid, oxalic acid, acetic acid and citric acid;
the pH value is 5-8;
the concentration of the regulator is 0.5-1.5 mol/L;
the precipitation mode comprises precipitation in hot water;
the precipitation temperature is 55-95 ℃;
the precipitation time is 20-80 min.
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