CN114409834A - High molecular weight polyvinyl alcohol and preparation method thereof - Google Patents
High molecular weight polyvinyl alcohol and preparation method thereof Download PDFInfo
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- CN114409834A CN114409834A CN202210029883.3A CN202210029883A CN114409834A CN 114409834 A CN114409834 A CN 114409834A CN 202210029883 A CN202210029883 A CN 202210029883A CN 114409834 A CN114409834 A CN 114409834A
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- polyvinyl alcohol
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- ester polymer
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- 229920002451 polyvinyl alcohol Polymers 0.000 title claims abstract description 97
- 239000004372 Polyvinyl alcohol Substances 0.000 title claims abstract description 91
- 238000002360 preparation method Methods 0.000 title abstract description 15
- 238000007127 saponification reaction Methods 0.000 claims abstract description 65
- 238000000034 method Methods 0.000 claims abstract description 41
- 239000000178 monomer Substances 0.000 claims abstract description 33
- 229920001290 polyvinyl ester Polymers 0.000 claims abstract description 31
- 229920000642 polymer Polymers 0.000 claims abstract description 30
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 27
- 230000035484 reaction time Effects 0.000 claims abstract description 7
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 47
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 29
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 27
- 239000003054 catalyst Substances 0.000 claims description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 239000002904 solvent Substances 0.000 claims description 19
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 11
- 239000002105 nanoparticle Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 10
- 239000004408 titanium dioxide Substances 0.000 claims description 9
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 6
- 229910052753 mercury Inorganic materials 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 125000000129 anionic group Chemical group 0.000 claims description 3
- 125000002091 cationic group Chemical group 0.000 claims description 3
- 239000003960 organic solvent Substances 0.000 claims description 3
- 230000001678 irradiating effect Effects 0.000 claims 1
- 229920002689 polyvinyl acetate Polymers 0.000 abstract description 29
- 239000000126 substance Substances 0.000 abstract description 12
- 238000002834 transmittance Methods 0.000 abstract description 10
- 239000012535 impurity Substances 0.000 abstract description 6
- 239000007788 liquid Substances 0.000 abstract description 6
- 239000002699 waste material Substances 0.000 abstract description 6
- 239000004970 Chain extender Substances 0.000 abstract description 4
- 239000003995 emulsifying agent Substances 0.000 abstract description 4
- 238000010438 heat treatment Methods 0.000 abstract description 2
- 238000004904 shortening Methods 0.000 abstract 1
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 80
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 36
- 239000000243 solution Substances 0.000 description 23
- 238000006243 chemical reaction Methods 0.000 description 17
- 239000002585 base Substances 0.000 description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 9
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 6
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 5
- -1 azo compound Chemical class 0.000 description 5
- 239000011118 polyvinyl acetate Substances 0.000 description 5
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 4
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 4
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- UEEJHVSXFDXPFK-UHFFFAOYSA-N N-dimethylaminoethanol Chemical compound CN(C)CCO UEEJHVSXFDXPFK-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 3
- 239000003999 initiator Substances 0.000 description 3
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 3
- 150000003254 radicals Chemical class 0.000 description 3
- 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 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- UEEJHVSXFDXPFK-UHFFFAOYSA-O N-dimethylethanolamine Chemical compound C[NH+](C)CCO UEEJHVSXFDXPFK-UHFFFAOYSA-O 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000012972 dimethylethanolamine Substances 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 238000005227 gel permeation chromatography Methods 0.000 description 2
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 150000007524 organic acids Chemical class 0.000 description 2
- 150000001451 organic peroxides Chemical class 0.000 description 2
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 2
- 239000003505 polymerization initiator Substances 0.000 description 2
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- OWXJKYNZGFSVRC-NSCUHMNNSA-N (e)-1-chloroprop-1-ene Chemical compound C\C=C\Cl OWXJKYNZGFSVRC-NSCUHMNNSA-N 0.000 description 1
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- 125000003903 2-propenyl group Chemical group [H]C([*])([H])C([H])=C([H])[H] 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 239000004342 Benzoyl peroxide Substances 0.000 description 1
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 1
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 1
- 229920002978 Vinylon Polymers 0.000 description 1
- 238000004847 absorption spectroscopy Methods 0.000 description 1
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 1
- 125000002777 acetyl group Chemical class [H]C([H])([H])C(*)=O 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003377 acid catalyst Substances 0.000 description 1
- 150000001252 acrylic acid derivatives Chemical class 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 125000000751 azo group Chemical group [*]N=N[*] 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 238000012662 bulk polymerization Methods 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000012986 chain transfer agent Substances 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- LDHQCZJRKDOVOX-NSCUHMNNSA-N crotonic acid Chemical compound C\C=C\C(O)=O LDHQCZJRKDOVOX-NSCUHMNNSA-N 0.000 description 1
- 229910052805 deuterium Inorganic materials 0.000 description 1
- 125000004431 deuterium atom Chemical group 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000007720 emulsion polymerization reaction Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- NKSJNEHGWDZZQF-UHFFFAOYSA-N ethenyl(trimethoxy)silane Chemical compound CO[Si](OC)(OC)C=C NKSJNEHGWDZZQF-UHFFFAOYSA-N 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000003205 fragrance Substances 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 239000000499 gel Substances 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000010534 mechanism of action Effects 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- WXPWPYISTQCNDP-UHFFFAOYSA-N oct-7-en-1-ol Chemical compound OCCCCCCC=C WXPWPYISTQCNDP-UHFFFAOYSA-N 0.000 description 1
- 125000002347 octyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 239000000123 paper Substances 0.000 description 1
- HVAMZGADVCBITI-UHFFFAOYSA-M pent-4-enoate Chemical compound [O-]C(=O)CCC=C HVAMZGADVCBITI-UHFFFAOYSA-M 0.000 description 1
- 238000013032 photocatalytic reaction Methods 0.000 description 1
- QYUMESOEHIJKHV-UHFFFAOYSA-M prop-2-enamide;trimethyl(propyl)azanium;chloride Chemical compound [Cl-].NC(=O)C=C.CCC[N+](C)(C)C QYUMESOEHIJKHV-UHFFFAOYSA-M 0.000 description 1
- UIIIBRHUICCMAI-UHFFFAOYSA-N prop-2-ene-1-sulfonic acid Chemical compound OS(=O)(=O)CC=C UIIIBRHUICCMAI-UHFFFAOYSA-N 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000010557 suspension polymerization reaction Methods 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 239000012209 synthetic fiber Substances 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- LDHQCZJRKDOVOX-UHFFFAOYSA-N trans-crotonic acid Natural products CC=CC(O)=O LDHQCZJRKDOVOX-UHFFFAOYSA-N 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/12—Hydrolysis
-
- 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
- C08F2/00—Processes of polymerisation
- C08F2/46—Polymerisation initiated by wave energy or particle radiation
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- 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 a high molecular weight polyvinyl alcohol and a preparation method thereof, wherein the method comprises the steps of firstly polymerizing monomers by utilizing a photopolymerization method to obtain a polyvinyl ester polymer, and then carrying out saponification reaction on the polyvinyl ester polymer to obtain the high molecular weight polyvinyl alcohol with high molecular weight polymerization degree and excellent solution transmittance. The invention adopts the photopolymerization method to prepare the polyvinyl ester polymer, and the process does not contain chain extender or emulsifier, thereby not leaving impurities and shortening the reaction time. The photopolymerization method can reduce the amount of soluble substances in the PVAc saponification waste liquid and the amount of insoluble substances in the PVA solution obtained by saponification of the PVAc, thereby improving the transmittance of the PVA solution and reducing the aroma generated during heating, etc., as compared with the conventional polymerization method.
Description
Technical Field
The invention relates to the technical field of polyvinyl alcohol, and particularly relates to high molecular weight polyvinyl alcohol and a preparation method thereof.
Background
Polyvinyl alcohol is an important chemical raw material, and can be used for manufacturing polyvinyl acetal, gasoline-resistant pipelines, vinylon synthetic fibers, fabric treating agents, emulsifiers, paper coatings, adhesives, glue water and the like. The polymerization methods of polyvinyl alcohol known so far include solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, and the like. Polyvinyl ester polymers (PVAc) obtained by polymerizing vinyl acetate (VAc) are converted into industrially useful polyvinyl alcohol (PVA) by saponification. Among them, persulfate (e.g., potassium persulfate), azo compounds, azobisisobutyronitrile, and organic peroxides (benzoyl peroxide) are generally used as a polymerization initiator to participate in polymerization. There are researchers preparing ethylene and VAc by using a polymerization solvent of methanol or t-butanol and a radical initiator having a semi-hydroxyl group. The copolymer obtained by copolymerization can provide a film having excellent surface properties after the saponification reaction. There have also been studies showing that PVAc obtained by solution polymerization of VAc in the presence of certain organic acids or salts thereof can be saponified to give a PVA with an excellent pure white color. In addition, PVAc obtained by solution polymerization of VAc in the presence of a specific organic acid decreases the degree of polymerization of PVA after saponification.
However, when PVAc prepared by the above-mentioned conventional polymerization method is subjected to saponification, a large amount of soluble substances are contained in a waste liquid generated therefrom, which not only causes environmental pollution, but also causes an increase in treatment cost due to clogging of a filter during the treatment of the waste liquid. On the other hand, PVA is generally dissolved in a solvent (e.g., water) and used in the form of a solution. However, since the PVA obtained by the conventional method contains many insoluble substances insoluble in a solvent such as water, the aqueous PVA solution has a problem of a decrease in the transparency of the solution. In addition, PVA produced using a persulfate, an azo compound or an organic peroxide as a polymerization initiator has a problem that an aromatic property is generated when heating.
Disclosure of Invention
The purpose of the present invention is to provide a high-molecular-weight polyvinyl alcohol having a high-molecular-weight polymerization degree and excellent solution transmittance.
It is another object of the present invention to provide a process for producing a high molecular weight polyvinyl alcohol by a photopolymerization method and a saponification reaction, which can reduce not only the amount of soluble substances in a waste liquid resulting from saponification of PVAc and the amount of insoluble substances in a PVA solution, but also the fragrance and the like generated when the PVA is heated.
The technical problem to be solved by the invention is realized by adopting the following technical scheme.
The invention provides a preparation method of high molecular weight polyvinyl alcohol, which comprises the steps of polymerizing monomers by utilizing a photopolymerization method to obtain a polyvinyl ester polymer, and then carrying out saponification reaction on the polyvinyl ester polymer to obtain the high molecular weight polyvinyl alcohol, wherein the monomers comprise vinyl acetate.
The invention provides high molecular weight polyvinyl alcohol which is prepared by the preparation method, wherein the viscosity average polymerization degree of the high molecular weight polyvinyl alcohol is 50-30000, and the saponification degree is more than 60 mol%.
The high molecular weight polyvinyl alcohol and the preparation method thereof have the beneficial effects that:
the present invention can obtain a polyvinyl ester polymer by polymerizing monomers by a photopolymerization method, and then saponify the polyvinyl ester polymer to obtain a high molecular weight polyvinyl alcohol having a high molecular weight polymerization degree and an excellent solution transmittance. The process of preparing polyvinyl ester polymer by photopolymerization method does not contain chain extender or emulsifier, so that no impurities remain and the reaction time can be shortened. The photopolymerization method can reduce the amount of soluble substances in the PVAc saponification waste liquid, and also reduce the amount of insoluble substances in the PVA solution obtained by saponification of the PVAc, thereby improving the transmittance of the PVA solution and reducing the aroma generated when the PVA solution is heated, and the like, as compared with the conventional polymerization method.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a flow diagram of the preparation of a high molecular weight polyvinyl alcohol of the present invention;
FIG. 2 is a graph showing the relationship between the concentration of hydrochloric acid and the conversion rate of vinyl acetate;
FIG. 3 is a graph of hydrochloric acid concentration versus vinyl acetate polymerization rate.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The high molecular weight polyvinyl alcohols and the methods for preparing the same according to the embodiments of the present invention will be described in detail below.
Referring to fig. 1, an embodiment of the present invention provides a method for preparing high molecular weight polyvinyl alcohol, in which a photopolymerization method is used to polymerize monomers to obtain a polyvinyl ester polymer, and then the polyvinyl ester polymer is subjected to a saponification reaction to obtain high molecular weight polyvinyl alcohol, wherein the monomers include vinyl acetate. The vinyl acetate of the present invention can be obtained commercially, for example, from Tiande chemical Industrial control Co., Ltd.
The process of preparing the polyvinyl ester polymer by adopting the photopolymerization method does not contain a chain extender or an emulsifier, does not only leave impurities, and can also shorten the reaction time. After the polyvinyl ester polymer is prepared by the photopolymerization method, the polyvinyl ester polymer is saponified to prepare the high molecular weight polyvinyl alcohol with excellent transmissivity. The photopolymerization method can reduce the amount of soluble substances in the PVAc saponification waste liquid, and also reduce the amount of insoluble substances in the PVA solution obtained by saponification of the PVAc, thereby improving the transmittance of the PVA solution and reducing the aroma generated when the PVA solution is heated, and the like, as compared with the conventional polymerization method.
Further, in a preferred embodiment of the present invention, the monomer further comprises a comonomer copolymerizable with the vinyl acetate. Specifically, the comonomers include nonionic monomers, cationic monomers, and anionic monomers. Nonionic monomers include olefins (e.g., ethylene and propylene), hydroxy olefins (e.g., 7-octen-1-ol), (meth) acrylates (e.g., methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate), allyl compounds, allyl acetate, chloropropene, (meth) acrylonitrile, vinyltrimethoxysilane, and the like. Anionic monomers include itaconic acid, maleic anhydride, (meth) acrylic acid, fumaric acid, crotonic acid, (meth) allylsulfonic acid, and the like. The cationic monomer includes 3- (meth) acrylamide-propyltrimethylammonium chloride, and the like. It is to be understood that in the preferred embodiment of the present invention, the amount of comonomer in the monomer is minimized to obtain PVA of high purity. More preferably, the monomer is vinyl acetate.
Further, in a preferred embodiment of the present invention, the step of polymerizing the monomer by a photopolymerization method comprises: mixing titanium dioxide nanoparticles (TiO)2NPs), monomers, hydrochloric acid and water are put into a reactor, and the reactor is irradiated for 1.5-2.5 hours under a high-pressure mercury lamp, so that the polyvinyl ester polymer is obtained. Wherein the mass ratio of the titanium dioxide nanoparticles to the monomer to the hydrochloric acid is 1: 9-12: 0.09 to 0.1. The mass-to-volume ratio of the titanium dioxide nanoparticles to the water is: 1: 75-85 (g/mL). The molar concentration of the hydrochloric acid is 0.0025-0.005 mol/L. The invention takes titanium dioxide nano-particles as a photopolymerization initiator, and adds hydrochloric acid into a reactor to improve the photoinitiation efficiency, thereby remarkably improving the yield of PVAc. By adding hydrochloric acid at the molar concentrations described above, VAc is made to have a higher conversion and polymerization rate. The titanium dioxide nanoparticles and hydrochloric acid of the present invention can be obtained commercially, for example, titanium dioxide nanoparticles can be obtained from Ningbo Minoxidin New materials science and technology Co., Ltd, hydrochloric acid can be obtained from Longyan Tianmei trade Co., Ltd, and the like.
In the present invention, TiO2The ultraviolet wavelength range for nanoparticle action is 365nm, and the photopolymerization initiated by the nanoparticle depends on the structure of the reaction monomer. In particular, TiO2The mechanism of the NPs photocatalytic reaction is as follows:
in TiO2In NPs, when irradiated with ultraviolet rays, a pair of electrons is formed.
TiO2 hv h+(TiO2)+e-(TiO2)
Electrons undergo redox reactions in water, which rearrange the charge (formula):
h+(TiO2)+H2O→H++HO·
thus, HO acts as a radical initiator during photopolymerization.
The mechanism of action of HCl in water is shown below:
DCl→D++Cl-
D++H2O→HDO+H+
D++e-(TiO2)hv D.+
deuterium atoms are located at the end of the PVAc chain, and the reaction mechanism is as follows:
R˙+M→RM˙
RM˙+(n-1)M→R(M)n˙
wherein, R: free radical, M: VAc monomer, D: deuterium radicals.
Further, in a preferred embodiment of the present invention, the step of subjecting the polyvinyl ester polymer to saponification comprises:
primary saponification reaction: and dissolving the polyvinyl ester polymer in a first solvent containing a first base catalyst to carry out saponification reaction to obtain the polyvinyl alcohol. Wherein the first solvent is a solvent capable of dissolving the polyvinyl ester polymer, which comprises water, a lower alcohol, or a mixture thereof. The lower alcohol may be one selected from methanol, ethanol, propanol and butanol. Preferably, the first solvent is methanol. The polyvinyl ester polymer has higher solubility in methanol and lower methanol cost, thereby reducing the production cost of enterprises. The concentration of the polyvinyl ester polymer dissolved in methanol varies depending on the molecular weight, and the concentration of the polyvinyl ester polymer dissolved in methanol is 1 to 30 wt%.
The temperature of the primary saponification reaction is 20-80 ℃, and the reaction time is 30-120 min. Preferably, the temperature of the primary saponification reaction is 30 to 70 ℃. More preferably, the temperature of the primary saponification reaction is 40 to 60 ℃. When the reaction temperature is lower than 20 ℃, there is a problem that the saponification reaction is too late or polyvinyl alcohol having a very low saponification degree is produced. When the reaction temperature is more than 80 ℃, the viscosity rapidly increases and gelation occurs during saponification, side reactions of a saponification catalyst such as an alkali easily occur, and the polyvinyl alcohol easily changes its color.
Secondary saponification reaction: and dissolving the polyvinyl alcohol in a second solvent, and then adding a second base catalyst to carry out saponification reaction to obtain the high molecular weight polyvinyl alcohol. The second solvent is a solvent capable of completely dissolving the polyvinyl alcohol generated by the primary saponification reaction. The second solvent is selected from one of water, a water/alcohol mixture or an organic solvent/alcohol mixture. Wherein the alcohol may be selected from one of methanol, ethanol, propanol and butanol. Methanol is preferably used from the viewpoint of solubility and cost. The organic solvent is selected from solvents that can dissolve both polyvinyl ester and polyvinyl alcohol. Such as dimethyl sulfoxide (DMSO), Dimethylformamide (DMF), en-methylpyrrolidone (N) -methylpyrrolidone, dimethylacetamide, ethylenediamine, and the like. The first solvent and the second solvent of the present invention are both commercially available, and for example, methanol is available from tin-free three-in-one chemical company, ltd.
The temperature of the secondary saponification reaction is 40-120 ℃, and the reaction time is 30-120 min. Preferably, the temperature of the secondary saponification reaction is 50 to 100 ℃. More preferably, the temperature of the secondary saponification reaction is 60 to 90 ℃. When the reaction temperature is 40 ℃ or lower, the saponification reaction proceeds relatively late due to insufficient dissolution of the polyvinyl alcohol, the polyvinyl alcohol having a low saponification degree is produced, the catalyst is likely to cause problems such as side reactions, and the produced polyvinyl alcohol is also likely to be discolored.
The weight part ratio of the polyvinyl ester polymer to the first base catalyst to the second base catalyst is 100: 0.1-5: 1 to 20. Preferably, the first base catalyst and the second base catalyst are sodium hydroxide or potassium hydroxide. In general, an acid catalyst or an alkali catalyst can be used as a catalyst for the saponification reaction. However, the acid saponification method requires a high reactor material and has a low deoxidation speed, and therefore, the method selects an alkali catalyst as the catalyst for the saponification reaction. The base catalyst of the present invention is commercially available, and for example, sodium hydroxide is available from Cangzhou Henakawa chemical Co., Ltd.
The first base catalyst is used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polyvinyl ester polymer. Preferably, the first base catalyst is used in an amount of 0.5 to 4 parts by weight, and the second catalyst is used in an amount of 3 to 15 parts by weight. More preferably, the first base catalyst is used in an amount of 1 to 3 parts by weight, and the second base catalyst is used in an amount of 5 to 10 parts by weight. When the amount of the first base catalyst is less than 0.1 part by weight, there are problems that the saponification reaction is too late or polyvinyl alcohol having an extremely low saponification degree is produced. When the first base catalyst is used in an amount of more than 5 parts by weight, there are problems in that viscosity suddenly increases and gels and polyvinyl alcohol easily discolors during saponification. When the amount of the second base catalyst is less than 1 part by weight, there are problems that the saponification reaction is too late, polyvinyl alcohol having an extremely low saponification degree is produced, or the produced polyvinyl alcohol is liable to be discolored.
The saponification reaction of the present invention includes a primary saponification reaction and a secondary saponification reaction. Polyvinyl alcohol having less impurities can be obtained by the primary saponification, and then polyvinyl alcohol having excellent transmittance, a high degree of saponification and a high molecular weight can be prepared by subjecting PVA obtained by the primary saponification to the secondary saponification. It should be noted that the reaction conditions of the secondary saponification reaction may be the same as or similar to the primary saponification reaction.
The invention also provides high molecular weight polyvinyl alcohol which is prepared by the preparation method, wherein the viscosity-average polymerization degree of the high molecular weight polyvinyl alcohol is 50-30000, and the saponification degree is more than 60 mol%. Preferably, the high molecular weight polyvinyl alcohol has a viscosity average degree of polymerization of 1000 to 25000 and a degree of saponification of 70 to 99.9 mol%. More preferably, the viscosity average degree of polymerization of the high molecular weight polyvinyl alcohol is 2000 to 20000.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
The high molecular weight polyvinyl alcohol provided in this example was prepared according to the following steps:
preparation of PVAc: adding TiO into the mixture2NPs (1g/L), VAc (0.125mol/L) and 0.0025mol/L hydrochloric acid are put into a reactor80mL of water was added to the reactor, and the mixture was continuously irradiated with a 500W high-pressure mercury lamp for 2 hours to obtain polyvinyl acetate.
Preparation of high molecular weight PVA: 100g of polyvinyl acetate was completely dissolved in 1900g of methanol at 60 ℃ to obtain a first solution. 2g of sodium hydroxide was dissolved in 98g of methanol at 40 ℃ to obtain a second solution. Then, the second solution was added to the first solution at 40 ℃ to carry out a primary saponification reaction to obtain PVA.
NaOH was dissolved in normal temperature water to prepare a normal temperature alkaline aqueous solution having a pH of 12. Then, 1 mol% of PVA (degree of saponification: 99.00 mol%, mass% 25%) was added to the alkaline aqueous solution, and stirred in a two-stage impeller stirrer for 30min to perform a secondary saponification reaction. After the reaction is finished, carrying out primary washing by using distilled water at 15 ℃, then adding acetic acid to neutralize the alkaline aqueous solution, and carrying out secondary washing by using distilled water at 15 ℃ to obtain the high molecular weight polyvinyl alcohol.
Example 2
In this example, a high molecular weight polyvinyl alcohol is provided, prepared according to the procedure of example 1 and which differs from example 1 in that:
preparation of PVAc: adding TiO into the mixture2NPs (1g/L), VAc (0.125mol/L) and 0.005mol/L hydrochloric acid were put into a reactor and 80mL of water was added, followed by continuous irradiation with a 500W high-pressure mercury lamp for 2 hours to obtain polyvinyl acetate.
Example 3
In this example, a high molecular weight polyvinyl alcohol is provided, prepared according to the procedure of example 1 and which differs from example 1 in that:
preparation of PVAc: adding TiO into the mixture2NPs (1g/L), VAc (0.125mol/L) and 0.01mol/L hydrochloric acid were put into a reactor and 80mL of water was added, followed by continuous irradiation with a 500W high-pressure mercury lamp for 2 hours to obtain polyvinyl acetate.
Comparative example 1
This comparative example provides a polyvinyl alcohol, prepared according to the procedure of example 1, and which differs from example 1 in that:
preparation of PVAc: 35 wt% of VAc and a chain transfer agent TBA (t-butanol 3.5 wt%) were added to water and placed in a reactor, and potassium persulfate (KPS)/N, N-Dimethylethanolamine (DMEA), KPS (set to 0.5 wt% based on VAc) and hydroquinone solution (0.5g/L) were sequentially added to react for 8 hours to obtain PVAc, which was then washed and filtered, and then dried by gamma distillation at 40 ℃. Wherein, potassium persulfate (KPS)/N, N-Dimethylethanolamine (DMEA) is mixed according to the mass ratio of 1: 3. In the mixed solution, the mass percent of KPS is 1.75 wt%, the mass percent of N, N dimethyl ethanolamine is 5.25 wt%, and the mass percent of hydroquinone is 0.5 wt%.
Comparative example 2
This comparative example provides a polyvinyl alcohol, prepared according to the procedure of example 1, and which differs from example 1 in that:
preparation of PVAc: adding TiO into the mixture2NPs (1g/L) and VAc (0.125mol/L) were placed in a reactor and 80mL of water was added, followed by continuous irradiation with a 500W high pressure mercury lamp for 2 hours to obtain polyvinyl acetate.
Test example 1
This test example was conducted by measuring the weight average molecular weights and number average molecular weights of the high molecular weight polyvinyl alcohols of examples 1 to 3 and the polyvinyl alcohol of comparative example 1 by Gel Permeation Chromatography (GPC) analysis to determine the polymerization degrees thereof, measuring the solution transmittances at 400 to 600nm of the high molecular weight polyvinyl alcohols of examples 1 to 3 and the polyvinyl alcohol of comparative example 1 by ultraviolet-visible light absorption spectroscopy (UV-VIS) and measuring the impurity contents of the high molecular weight polyvinyl alcohols of examples 1 to 3 and the polyvinyl alcohol of comparative example 1 by inductively coupled plasma mass spectrometry (ICP-MS). The measurement results are shown in table 1:
TABLE 1 parameter Table for high molecular weight polyvinyl alcohol and polyvinyl alcohol
As can be seen from Table 1, the high molecular weight polyvinyl alcohols of examples 1-3 have higher purity and less than 1000ppm of impurities than the polyvinyl alcohol of comparative example 1. And the solution transmittance of the high molecular weight polyvinyl alcohol of example 3 was 99.8%, indicating that it had an excellent solution transmittance. The invention adopts a photopolymerization method to prepare PVAc, and the polymerization degree of the PVAc is not influenced by the chain extender, so that the high molecular weight polyvinyl alcohol which cannot be obtained by the conventional polymerization method can be prepared. As can be seen from Table 1, the polymerization degree of the high molecular weight polyvinyl alcohol of example 3 can reach 13200.
Test example 2
This test example was conducted to investigate the relationship between the concentration of hydrochloric acid and the monomer conversion rate by photopolymerization of vinyl acetate and hydrochloric acid of various concentrations. Wherein, Table 2 is a graph comparing the conversion and PVAc polymerization degrees of the high molecular weight polyvinyl alcohols of examples 1-3 and the polyvinyl alcohol of comparative example 2. FIG. 2 is a graph showing the relationship between the concentration of hydrochloric acid and the conversion rate of vinyl acetate. FIG. 3 is a graph of hydrochloric acid concentration versus vinyl acetate polymerization rate.
TABLE 2 graph comparing conversion and PVAc polymerization
As can be seen from table 2, the monomer conversion of vinyl acetate depends on the concentration of hydrochloric acid. Within a certain range, monomer conversion increases with increasing hydrochloric acid concentration. When the concentration of hydrochloric acid is 0.01mol/L, the monomer conversion rate reaches 98.3%, and the polymerization degree of PVAc reaches 15400.
As can be seen from fig. 2 and 3, the higher the conversion of VAc (fig. 2) and the higher the polymerization rate (fig. 3) as the hydrochloric acid concentration increases.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (10)
1. A method for preparing high molecular weight polyvinyl alcohol is characterized in that a photopolymerization method is utilized to polymerize monomers to obtain a polyvinyl ester polymer, and then the polyvinyl ester polymer is subjected to saponification reaction to obtain the high molecular weight polyvinyl alcohol, wherein the monomers comprise vinyl acetate.
2. The method of claim 1, wherein the monomers further comprise a comonomer copolymerizable with the vinyl acetate, the comonomer being selected from the group consisting of nonionic monomers, cationic monomers and anionic monomers.
3. The method for preparing high molecular weight polyvinyl alcohol according to claim 1, wherein the step of polymerizing the monomer by photopolymerization comprises:
and (3) putting the titanium dioxide nanoparticles, the monomer, hydrochloric acid and water into a reactor, and irradiating for 1.5-2.5 hours under a high-pressure mercury lamp to obtain the polyvinyl ester polymer.
4. The method for preparing high molecular weight polyvinyl alcohol according to claim 3, wherein the mass ratio of the titanium dioxide nanoparticles, the monomer and the hydrochloric acid is 1: 9-12: 0.09 to 0.1. The mass-to-volume ratio of the titanium dioxide nanoparticles to the water is: 1: 75-85 (g/mL).
5. The method according to claim 3, wherein the hydrochloric acid has a molar concentration of 0.0025 to 0.005 mol/L.
6. The method for producing a high molecular weight polyvinyl alcohol according to claim 1, wherein the step of subjecting the polyvinyl ester polymer to saponification comprises:
primary saponification reaction: dissolving the polyvinyl ester polymer in a first solvent containing a first base catalyst to carry out saponification reaction to obtain polyvinyl alcohol;
secondary saponification reaction: and dissolving the polyvinyl alcohol in a second solvent, and then adding a second base catalyst to carry out saponification reaction to obtain the high molecular weight polyvinyl alcohol.
7. The method for producing a high molecular weight polyvinyl alcohol according to claim 6, wherein the first solvent is a solvent capable of dissolving a polyvinyl ester polymer, the temperature of the primary saponification reaction is 20 to 80 ℃, and the reaction time is 30 to 120 min.
8. The method according to claim 6, wherein the second solvent is one selected from water, a water/alcohol mixture, and an organic solvent/alcohol mixture, and the temperature of the secondary saponification reaction is 40 to 120 ℃ and the reaction time is 30 to 120 min.
9. The method for preparing high molecular weight polyvinyl alcohol according to claim 6, wherein the weight part ratio of the polyvinyl ester polymer, the first base catalyst and the second base catalyst is 100: 0.1-5: 1 to 20.
10. A high molecular weight polyvinyl alcohol produced by the production method according to any one of claims 1 to 9, wherein the viscosity average degree of polymerization of the high molecular weight polyvinyl alcohol is 50 to 30000 and the degree of saponification is more than 60 mol%.
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