CN102020735B - Purification method of polyvinyl alcohol - Google Patents
Purification method of polyvinyl alcohol Download PDFInfo
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- CN102020735B CN102020735B CN200910190885.5A CN200910190885A CN102020735B CN 102020735 B CN102020735 B CN 102020735B CN 200910190885 A CN200910190885 A CN 200910190885A CN 102020735 B CN102020735 B CN 102020735B
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Abstract
The invention relates to a purification method of polyvinyl alcohol obtained by alkali catalysis on polyvinyl acetate. In the method, a solution in which polyvinyl alcohol is undissolved or difficult to be dissolved while residues of polyvinyl alcohol are soluble is taken as a solvent, and purification on polyvinyl alcohol is carried out. The invention requires no modification on the traditional mature and complete industrialized PVA preparation process, thus being beneficial to implementation of industrialization, and ash content of the polyvinyl alcohol purified by the method in the invention is close to or less than 0.1%; and the solvent required in the process for preparing polyvinyl alcohol from polyvinyl acetate by hydrolysis or the product obtained by the process is taken as a solvent for purification treatment of polyvinyl alcohol, the produced waste liquor can be merged into the original waste liquor recovery and purification system, the cost is effectively reduced, and the separation of the polyvinyl alcohol after being purified is convenient.
Description
Technical field
The present invention relates to a kind of purification process of polyvinyl alcohol, be specially adapted to the purification process of the polyvinyl alcohol that catalysis with alkaline polyvinyl acetate (PVA) obtains.
Background technology
Because polyvinyl alcohol (hereinafter referred to as PVA) is nontoxic, there is well water-soluble and good biocompatibility, much special purposes is had in fields such as medicine and lives, both at home and abroad to all very large (the UhrichK E of the demand of polyvinyl alcohol, Canizarro S M, et a1.Polymeric systems for control drug release [J] .ChemRev, 1999,99:3181-3198).Polyvinyl alcohol obtains mainly through acid system or alkali process hydrolysis polyvinyl acetate (PVA).Wherein, owing to there is a lot of shortcoming in Acid hydrolysis, as slow in speed of response, corrosive equipment, product are easily painted etc., less employing in the industrial production; The method that polyvinyl alcohol prepared by the alkali process hydrolysis polyvinyl acetate (PVA) being catalyzer with sodium hydroxide NaOH has that technique is simple, process safety, can the advantage such as continuous high-efficient production, be widely used in industrial production.But, traditional base catalysis technique, due to the existence of the factor such as kind and unavoidable side reaction of catalyzer, a certain amount of sodium-acetate and a small amount of catalyst n aOH can be contained in the finished product polyvinyl alcohol, this part residue makes product polyvinyl alcohol purity drop, affects performance and the use range of polyvinyl alcohol.Improve polyvinyl alcohol purity and can effectively improve polyvinyl alcohol quality, expand the range of application of polyvinyl alcohol.
At present, in reduction PVA product, the method for inorganic content, raising polyvinyl alcohol purity mainly contains following several:
1, take ammoniacal liquor as catalyzer (Steffenssen Otto, Johnsen Henry, Johnsen Reidar, Processfor the production of polyvinyl alcohol [P], DE948087,1956) prepare ashless component polyethylene alcohol.Because the alkalescence of ammonia is very weak, be difficult to catalytic hydrolysis polyvinyl acetate (PVA).Therefore, ammonia process is hydrolyzed the polyvinyl ester that can only be used for compared with facile hydrolysis, as poly-Monochloro Acetic Acid vinyl acetate, poly-vinyl dichloroacetate ester and polyvinyl formate etc., can not be used for catalysis polyvinyl acetate (PVA), not possess industrialized meaning.
2, be that high purity white polyvinyl alcohol prepared by catalyzer (Griffith Bowen, Alcoholysis of polyvinyl esters [P], US2464290,1949) with organic bases.Usual organic bases has higher toxicity and explosion hazard, and preparation is complicated, there is larger potential safety hazard, because which limit the industrial applications of the method.
3, potassium hydroxide KOH catalysis (Li Shengji work, Feng Baosheng translates, vinylon [M], Beijing: textile industry press, p249,1986) is adopted.Because the catalytic efficiency of KOH is higher than NaOH, and by product Potassium ethanoate (CH
3cOOK) solubleness in methyl alcohol is than sodium-acetate (CH
3cOONa) solubleness in methyl alcohol is large, therefore, uses KOH should be conducive to removing acetate from obtained PVA, thus obtains the polyvinyl alcohol of higher degree.But in fact because the consumption of KOH can not infinitely reduce and the molecular weight of KOH is greater than the molecular weight of NaOH (under the condition waiting alkali mol ratio acetate residual, use KOH to make catalyzer ash content and want high), simple use KOH substitutes NaOH and very effectively can not prepare the very high polyvinyl alcohol product of purity.
4, inorganic salt (Paul Halbig, Paul Wicht, Preparation ofpolyvinyl alcohol [P], US2940948,1960 in polyvinyl alcohol are removed in ion-exchange; Hayes Richard A, Removal of base residuesfrom poly (vinyl alcohol) reaction-slurries [P], US5425879,1995).This method can very effectively prepare highly purified PVA product under the condition not changing preparation technology in early stage, but when carrying out ion-exchange, first PVA must be dissolved (or being partly dissolved) in water, after metal ion to be removed, also the PVA of dissolving will be precipitated out again, energy consumption is very high, complex process, cost increases significantly, therefore in industrial application, has certain difficulty.
In addition, the above method needs the preparation of industrialization PVA technique to comparative maturity is perfect to make larger adjustment usually, has very large difficulty in actual applications.
Summary of the invention
The object of the present invention is to provide a kind of technique simple, effectively can remove the purification process of the polyvinyl alcohol of wherein residual inorganics.It need not change the preparation technology of polyvinyl alcohol, and just can reach by carrying out aftertreatment to obtained polyvinyl alcohol the effect reducing polyvinyl alcohol ash content.
The object of the present invention is achieved like this: a kind of purification process of polyvinyl alcohol, particularly for the polyvinyl alcohol that catalysis with alkaline polyvinyl acetate (PVA) is obtained, reduce the purification process of its ash content, its adopt polyvinyl alcohol insoluble or not easily molten wherein and in polyvinyl alcohol residue wherein solubleness large as solvent, purification process is carried out to polyvinyl alcohol.
Solvent or product that above-mentioned solvent is selected Vinyl Acetate Copolymer Ester hydrolysis to prepare to adopt in PVOH technique.
At least one in methyl alcohol, water, ethyl acetate selected by above-mentioned solvent; Especially the mixed solvent selecting first alcohol and water is good.
The temperature of above-mentioned purification process is 30 DEG C ~ 60 DEG C, usually conduct 10 ~ 60 minutes.
The treatment capacity of above-mentioned polyvinyl alcohol is: polyvinyl alcohol weight number and solvent volume portion rate are 10 ~ 50 parts: 50 ~ 90 parts.
Specifically, a kind of purification process of polyvinyl alcohol, it is at the temperature of 30 DEG C ~ 60 DEG C, 10 ~ 50 weight account polyethylene alcohol and 50 ~ 90 parts by volume solvent is stirred, and residue in polyvinyl alcohol is dissolved in a solvent; Then divide the solvent of molten residue of leaving away, more separating obtained polyvinyl alcohol is carried out drying; Wherein solvent is at least one in methyl alcohol, water, ethyl acetate.
Above-mentioned polyvinyl alcohol is particulate polyethylene alcohol, especially with through pulverizing and undried granule of polyvinyl alcohol is good.
If adopt first alcohol and water as solvent, both mixed volume ratios are 5: 1 is good.
The present invention has following advantage:
1, the present invention is the purification process that the polyvinyl alcohol obtained catalysis with alkaline polyvinyl acetate (PVA) carries out, and it does not need to do what adjustment to traditional comparatively ripe perfect preparation of industrialization PVA technique, is very beneficial for industrialized enforcement; And be close to 0.1% or lower through the ash content of the polyvinyl alcohol of the method for the invention purifying.
2. adopt methyl alcohol, water, ethyl acetate or their mixture as solvent, these solvents are also that Vinyl Acetate Copolymer Ester hydrolysis prepares solvent required in polyvinyl alcohol technique or product, therefore, the waste liquid adopting the present invention to produce can be incorporated to former devil liquor recovery, purification system, effectively reduces costs;
3. adopt methyl alcohol, water, ethyl acetate or their mixture as mixed solvent, can ensure to dissolve, when removing residual inorganics in polyvinyl alcohol, not dissolve polyvinyl alcohol, is conducive to the separation of polyvinyl alcohol after purifying.
Accompanying drawing explanation
Fig. 1 is that embodiment 4 gained polyvinyl alcohol is by infrared spectra spectrogram before and after the inventive method process;
Fig. 2 is that embodiment 4 gained polyvinyl alcohol is by XRD spectra before and after the inventive method process.
Embodiment:
Below by embodiment, the present invention is specifically described; what be necessary to herein means out is that the present embodiment is only used to further illustrate the present invention; can not be interpreted as limiting the scope of the invention, the person skilled in the art in this field can make some nonessential improvement and adjustment according to the content of foregoing invention.
On the whole, a kind of purification process of polyvinyl alcohol, it comprises the steps: at the temperature of 30 DEG C ~ 60 DEG C, and 10 ~ 50 weight account polyethylene alcohol and 50 ~ 90 parts by volume solvent are stirred 10 ~ 60 minutes, and the inorganics contained in polyvinyl alcohol is dissolved in a solvent; Then dividing leaves away is dissolved with the solvent of inorganic salt, then polyvinyl alcohol is carried out drying; Wherein solvent is at least one in methyl alcohol, water, ethyl acetate.
Embodiment 1: be distributed in the methyl alcohol of 75 parts by 25 parts of granule of polyvinyl alcohol (polymerization degree is 2400, and alcoholysis degree is 99%), stir 20min, then filter to isolate polyvinyl alcohol at 50 DEG C, dries at 60 DEG C, obtains high-purity polyvinyl alcohol.Measure polyvinyl alcohol ash content before and after process respectively according to national standard (GB 12010.7-89), the ash content of result display polyvinyl alcohol (polymerization degree is 2400, and alcoholysis degree is 99%) drops to 0.064% by before treatment 0.27%.
Embodiment 2: (polymerization degree is 2400 by 30 parts of granule of polyvinyl alcohol, alcoholysis degree is 99%) be distributed to the mixing solutions (methyl alcohol: water=5: 1 of the first alcohol and water of 70 parts, with volume basis) in, 30min is stirred at 40 DEG C, then polyvinyl alcohol is filtered to isolate, dry at 60 DEG C, obtain high-purity polyvinyl alcohol.Measure polyvinyl alcohol ash content before and after process respectively according to national standard (GB 12010.7-89), the ash content of result display polyvinyl alcohol (polymerization degree is 2400, and alcoholysis degree is 99%) drops to 0.043% by before treatment 0.27%.
Embodiment 3: be distributed in the ethyl acetate of 70 parts by 30 parts of polyvinyl alcohol (polymerization degree is 1700, and alcoholysis degree is 88%), stir 10min, then filter to isolate polyvinyl alcohol at 60 DEG C, dries at 60 DEG C, obtains high-purity polyvinyl alcohol.Measure polyvinyl alcohol ash content before and after process respectively according to national standard (GB 12010.7-89), the ash content of result display polyvinyl alcohol (polymerization degree is 1700, and alcoholysis degree is 88%) drops to 0.013% by before treatment 0.19%.
Certainly, in this example, also purification process can be carried out as solvent to polyvinyl alcohol by water.
Embodiment 4: (polymerization degree is 1700 by 20 parts of granule of polyvinyl alcohol, alcoholysis degree is 99%) be distributed to the methyl alcohol of 80 parts and the mixing solutions (methyl alcohol: ethyl acetate=9: 1 of ethyl acetate, with volume basis) in, 60min is stirred at 30 DEG C, then polyvinyl alcohol is filtered to isolate, dry at 60 DEG C, obtain high-purity polyvinyl alcohol.Measure polyvinyl alcohol ash content before and after process respectively according to national standard (GB12010.7-89), the ash content of result display polyvinyl alcohol (polymerization degree is 1700, and alcoholysis degree is 99%) drops to 0.12% by before treatment 0.4%.
With further reference to Fig. 1 and Fig. 2, find in FIG, undressed polyvinyl alcohol is at 1570cm
-1there is assorted peak at place, and polyvinyl alcohol is after treatment without this assorted peak, shows that the purity through processing PVA is improved; Find in fig. 2, before and after process, the XRD curve of polyvinyl alcohol almost overlaps, and shows to carry out on polyvinyl alcohol structure and the crystal property that purification process can not affect polyvinyl alcohol by the present invention program.
Claims (1)
1. a purification process for polyvinyl alcohol, is characterized in that: be 1700 by 20 parts of polymerization degree, alcoholysis degree be 99% granule of polyvinyl alcohol be distributed in the mixing solutions of 80 parts of methyl alcohol and ethyl acetate, methyl alcohol: ethyl acetate is 9:1, with volume basis; At 30 DEG C, stir 60min, then filter to isolate polyvinyl alcohol, dry at 60 DEG C, obtain high-purity polyvinyl alcohol.
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| CN200910190885.5A CN102020735B (en) | 2009-09-17 | 2009-09-17 | Purification method of polyvinyl alcohol |
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| CN102020735B true CN102020735B (en) | 2015-02-11 |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102863567B (en) * | 2011-07-07 | 2014-12-24 | 中国石油化工集团公司 | Preparation method of polyvinyl alcohol through low-alkali method |
| CN102617865A (en) * | 2012-03-22 | 2012-08-01 | 盛世泰科生物医药技术(苏州)有限公司 | Method for refining polyvinyl alcohol as pharmaceutic adjuvant for slow release control agent |
| CN103554314B (en) * | 2013-11-08 | 2015-12-02 | 安徽皖维集团有限责任公司 | Production method of high-purity polyvinyl alcohol |
| CN103709296B (en) * | 2013-12-30 | 2016-07-20 | 上海微谱化工技术服务有限公司 | The method extracting pure ethylene-ethylene vinyl-acetate copolymer |
| CN106279480B (en) * | 2015-06-09 | 2018-09-18 | 中国石油化工集团公司 | A kind of production method and device of polyvinyl alcohol |
| CN105837710A (en) * | 2016-03-31 | 2016-08-10 | 温州小伦包衣技术有限公司 | Preparation method for medicinal polyvinyl alcohol, and medicinal polyvinyl alcohol and application thereof |
| CN110590975A (en) * | 2018-06-12 | 2019-12-20 | 武汉武药科技有限公司 | Medicinal polyvinyl alcohol and preparation method thereof |
| CN110028602B (en) * | 2019-04-28 | 2021-09-10 | 安徽皖维高新材料股份有限公司 | Method for reducing impurity content in industrial polyvinyl alcohol |
| CN114409831A (en) * | 2022-01-02 | 2022-04-29 | 浙江尚能实业股份有限公司 | Method for purifying polyvinyl alcohol resin for diffusion source production |
| CN115873148B (en) * | 2022-12-21 | 2023-09-29 | 浙江瓯伦包衣技术有限公司 | Purification method and application of polyvinyl alcohol |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101092463A (en) * | 2006-12-18 | 2007-12-26 | 四川大学 | Method for preparing polyvinyl alcohol with low ash |
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| CN101092463A (en) * | 2006-12-18 | 2007-12-26 | 四川大学 | Method for preparing polyvinyl alcohol with low ash |
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