CN102108107A - Method for preparing polyvinyl alcohol with low polymerization degree - Google Patents
Method for preparing polyvinyl alcohol with low polymerization degree Download PDFInfo
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- CN102108107A CN102108107A CN 201110023154 CN201110023154A CN102108107A CN 102108107 A CN102108107 A CN 102108107A CN 201110023154 CN201110023154 CN 201110023154 CN 201110023154 A CN201110023154 A CN 201110023154A CN 102108107 A CN102108107 A CN 102108107A
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Abstract
The invention provides a method for preparing polyvinyl alcohol with low polymerization degree, which comprises: mixing a vinylacetate monomer and a methanol solvent in a mass ratio of (50-80):20, adding azodiisobutyronitrile serving as an initiator in an amount which is 0.05 to 0.5 percent based on the mass of the monomer, uniformly dripping aldehyde serving as a chain transfer agent in an amount which is 0.2 to 5 percent based on the mass of the monomer, and reacting for 2 to 5 hours at 50 to 71 DEG C to obtain polyvinyl acetate with low polymerization degree; dissolving the polyvinyl acetate in methanol to obtain polyvinyl acetate methanol solution at a concentration of 15 to 40 percent; and adding NaOH at 40 to 55 DEG C according to a NaOH to polymer molar ratio of 0.003 to 0.02, and performing alcoholysis for 10 to 90 minutes to obtain polyvinyl alcohol with low polymerization degree.
Description
Technical field
The present invention relates to the preparation method of polyvinyl alcohol, specifically is a kind of preparation method of polyvinyl alcohol with low degree of polymerization.
Background technology
Polyvinyl alcohol is a kind of important water-soluble high-molecular compound that grows up at the beginning of the 5O age in 20th century.Use very extensively, can be used to producd fibers, also can be used as chemical ﹠ blended fabric slurry, coating, tackiness agent, emulsifying agent, papermaking processing aid etc.Along with the continuous development of science and technology, urgent day by day to the demand of different polymerization degree, different alcoholysis degree polyvinyl alcohol.Find out that from a lot of researchs both domestic and external the PVA product is to the height two poles development, promptly the polymerization degree and alcoholysis degree are to higher and lower both direction development.The PVA product of these different polymerization degrees and alcoholysis degree has property, high added value and characteristics in short supply, and the PVA of low polymerization degree and alcoholysis degree is except that the general characteristic with conventional PVA (stable as solvability under water absorbability, ventilation property, nontoxicity, the high temperature), also has in the cold water advantages such as solvability is good, biodegradable.Therefore, purposes is widely being arranged aspect the non-fiber, as be used for industries such as paper conversion, tamanori, coating, film, medicine, makeup.The needs of environment in recent years protection particularly, Biodegradable material receives increasing concern just day by day.Though PVA is the environmentally degradable material in theory, its polymerization degree, alcoholysis degree, degree of crystallinity, tacticity etc. are all influential to biodegradability.The polymerization degree of PVA is low more, and its degradation rate is high more.Domestic polyvinyl alcohol range of product has only about 20, and based on high-polymerization degree, high alcoholysis degree product, seems very dull.Therefore, preparation low polymerization degree polyvinyl acetate (PVA) seems very urgent.
Because vinyl alcohol can not be with the unbound state stable existence, polyvinyl alcohol can not directly obtain from the vinyl alcohol polymerization.Many at present employing polyvinyl acetate (PVA) carry out solution alcoholysis preparation under base catalysis, promptly desire prepares polyvinyl alcohol oligomeric and degree, low alcoholysis level, must prepare the Vinyl Acetate Copolymer of low polymerization degree earlier.Xu Dongying (the synthetic Xu Dongying of the synthetic performance study of low polymerization degree, polyvinyl alcohol with low alcoholysis level---low polymerization degree polyvinyl acetate (PVA); Liao Zhengfu; The Su Tao synthon, 2005 03 phases) etc. be solvent with methyl alcohol, Diisopropyl azodicarboxylate is an initiator, adopts the right polyvinyl acetate (PVA) of radical polymerization synthesis of oligonucleotides, by regulating the volume proportion of raw material vinyl acetate and methyl alcohol, the polymerization degree that can regulate polyvinyl acetate (PVA).Mass ratio at Diisopropyl azodicarboxylate and vinyl acetate is 0. 2 %, during V (vinyl acetate): V (methyl alcohol)=50:50, reaction 4 h, can to obtain percent polymerization 87 %, the polymerization degree be 511 PVA.On forefathers' basis, (the preparation Zhang Qiaoling of polyvinyl alcohol with low degree of polymerization such as Zhang Qiaoling; Journey is former; Wang Wensheng; Thank imperial synthetic resins and plastics, 2008 25(4)) adopting vinyl acetate is monomer, select for use methyl alcohol as solvent, Diisopropyl azodicarboxylate make initiator, disulfide group ethanol is chain-transfer agent, with monomer vinyl acetate between to for plastic and solvent methanol with (60～80): 20 mass ratio mixes, adds the initiator Diisopropyl azodicarboxylate that accounts for monomer mass 0. 1 %～0.5 % and accounts for the chain-transfer agent disulfide group ethanol of monomer mass 0. 2 %～4 %, in 45～70 ℃ of reaction 2～4 h, make the low polymerization degree polyvinyl acetate (PVA) with the method for solution polymerization; Again the low polymerization degree polyvinyl acetate (PVA) is dissolved in and obtains the polyvinyl acetate (PVA) methanol solution that massfraction is 15 %～25 % in the methyl alcohol, add down massfraction 0. 5 %～3 %NaOH methanol solutions, alcoholysis 1～3 h that account for liquor capacity 10 %～25 % at 35～45 ℃, obtain the polymerization degree and be 50～500 PVA.
Usually, the preparation method of polyvinyl alcohol with low degree of polymerization is:
(1) the monomer vinyl acetate is mixed with the mass ratio of solvent methanol with 50 ~ 80:20;
(2) add the initiator Diisopropyl azodicarboxylate that accounts for monomer mass 0.05 ~ 0.5%;
(3) evenly drip the chain-transfer agent that accounts for monomer mass 0.2 ~ 5%,, make low polymerization degree according to vinyl acetate in 50 ~ 71 ℃ of reaction 2 ~ 5h;
(4) polyvinyl acetate (PVA) is dissolved in obtains 15 ~ 40% polyvinyl acetate (PVA) methanol solution in the methyl alcohol;
(5) in 40 ~ 55 ℃ of addings and polymkeric substance mol ratio be 0.003 ~ 0.02 NaOH, alcoholysis 10 ~ 90min makes polyvinyl alcohol with low degree of polymerization.
Depend merely on and reduce monomeric ratio, it is unpractical that the method for the methyl alcohol proportioning of increase solvent is applied to industrial production, because monomer conversion is too low, the solvent recuperation amount is excessive, production cost
Just higher.Use CCl4 also to have same problem as chain-transfer agent, promptly monomeric transformation efficiency is too low.If as chain-transfer agent,, needs to increase the Separation and Recovery operation, thereby increase production cost, and disulfide group ethanol has bigger because disulfide group ethanol is not easily separated with disulfide group ethanol
Toxicity has considerable influence to environment, and its foul smell can influence the organoleptic quality of product.Therefore operability, economy and the practicality of above-mentioned chain-transfer agent have much room for improvement.
Summary of the invention
The present invention has overcome the deficiency of prior art problem, provides a kind of manufacturing process simple, the method for preparing polyvinyl alcohol with low degree of polymerization that the chain-transfer agent separate easily reclaims.
The preparation method's of polyvinyl alcohol with low degree of polymerization provided by the invention characteristics are to utilize acetaldehyde as chain-transfer agent.
In the method provided by the invention, other steps are mixed the monomer vinyl acetate according to the method that provides in the prior art with the mass ratio of solvent methanol with 50 ~ 80:20; Add the initiator Diisopropyl azodicarboxylate that accounts for monomer mass 0.05 ~ 0.5%; Evenly drip the chain-transfer agent acetaldehyde that accounts for monomer mass 0.2 ~ 5%,, make the low polymerization degree polyvinyl acetate (PVA) in 50 ~ 71 ℃ of reaction 2 ~ 5h; Polyvinyl acetate (PVA) is dissolved in obtains 15 ~ 40% polyvinyl acetate (PVA) methanol solution in the methyl alcohol; In 40 ~ 55 ℃ of addings and polymkeric substance mol ratio is 0.003 ~ 0.02 NaOH, and alcoholysis 10 ~ 90min makes polyvinyl alcohol with low degree of polymerization.
Chain-transfer agent adopts acetaldehyde, and then the chain-transfer agent separate easily reclaims.In the polymeric kettle system, a large amount of acetaldehyde can reclaim by polymeric kettle top vapor condensation, and recycle, and a small amount of acetaldehyde is taken out of from the polymeric kettle bottom.The micro-acetaldehyde that side reaction produces in the production of carbide acetylene method polyvinyl alcohol can enter polymeric kettle along with Vinyl Acetate Monomer, the a small amount of acetaldehyde that comes out from the polymeric kettle bottom, enter polymerization process rectifying one tower and separate, therefore do not need to increase in addition the chain-transfer agent separating device from this top of tower; Chain-transfer agent acetaldehyde is controlled polymerization degree and polyvinyl acetate (PVA) monomer conversion height well, also is the percent polymerization height; Acetaldehyde is cheap with respect to other chain-transfer agent such as market value such as mercaptoethanol, 3-mercaptoethanol, has cost advantage as chain-transfer agent; Acetaldehyde is compared with other chain-transfer agents, and toxic is little, and is little to environmental influence.
Embodiment
Embodiment 1
Get the vinyl acetate between to for plastic 100g of purity 99.9%, methyl alcohol 54g adds in the there-necked flask of 400ml, adds the 0.12g Diisopropyl azodicarboxylate again, and stirring in water bath is heated to 62 ℃, drips chain-transfer agent acetaldehyde, drips 180min, keeps polyreaction 5h, stopped reaction.
Product is added methyl alcohol about 75 ℃, distill, obtain Vinyl Acetate Copolymer and methanol solution, add NaOH at 40～55 ℃ and carry out alcoholysis to remove Vinyl Acetate Monomer, continue 90min, stopped reaction, dry through washing, the polymerization degree of products therefrom is 300, percent polymerization 89%.
Embodiment 2
Get the vinyl acetate between to for plastic 100g of purity 99.9%, methyl alcohol 54g adds in the there-necked flask of 400ml, adds the 0.12g Diisopropyl azodicarboxylate again,, stirring in water bath is heated to 62 ℃, drips chain-transfer agent acetaldehyde, drips 240min, keeps polyreaction 5h, stopped reaction.
Product is added methyl alcohol about 75 ℃, distill, obtain Vinyl Acetate Copolymer and methanol solution, add NaOH at 40～55 ℃ and carry out alcoholysis to remove Vinyl Acetate Monomer, continue 90min, stopped reaction, dry through washing, the polymerization degree of products therefrom is 200, percent polymerization 85%.
According to the contrast of embodiment 1 and embodiment 2, with same reagent, increase the amount of chain-transfer agent acetaldehyde and prolong the dropping time, the products therefrom polymerization degree descends, and percent polymerization is more or less the same, and illustrates that such chain-transfer agent of use can well the controlled polymerization degree.
Embodiment 3
Get the vinyl acetate between to for plastic 100g of purity 99.9%, methyl alcohol 25g adds in the there-necked flask of 400ml, adds the 0.08g Diisopropyl azodicarboxylate again, stirring in water bath is heated to 62 ℃, drips chain-transfer agent acetaldehyde, and per minute drips 2-5 and drips, drip 150min, keep polyreaction 3h, stopped reaction.
Product is added methyl alcohol about 75 ℃, distill, obtain Vinyl Acetate Copolymer and methanol solution, add NaOH at 40～55 ℃ and carry out alcoholysis to remove Vinyl Acetate Monomer, continue 90min, stopped reaction, dry through washing, the polymerization degree of products therefrom is 380, percent polymerization 76.5%.
Embodiment 4
Get the vinyl acetate between to for plastic 100g of purity 99.9%, methyl alcohol 25g adds in the there-necked flask of 400ml, adds the 0.08g Diisopropyl azodicarboxylate again, stirring in water bath is heated to 62 ℃, drips chain-transfer agent acetaldehyde, and per minute drips 2-5 and drips, drip 120min, keep polyreaction 2.5h, stopped reaction.
Product is added methyl alcohol about 75 ℃, distill, obtain Vinyl Acetate Copolymer and methanol solution, add NaOH at 40～55 ℃ and carry out alcoholysis to remove Vinyl Acetate Monomer, continue 90min, stopped reaction, dry through washing, the polymerization degree of products therefrom is 350, percent polymerization 73.1%.
Claims (1)
1. the manufacture method of a polyvinyl alcohol with low degree of polymerization comprises adding the chain-transfer agent that accounts for monomer mass 0.2 ~ 5%, in 50 ~ 71 ℃ of reaction 2 ~ 5h, makes the low polymerization degree polyvinyl acetate (PVA), and it is characterized in that: described chain-transfer agent is an acetaldehyde.
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103897089A (en) * | 2014-04-01 | 2014-07-02 | 湖南省湘维有限公司 | Crystalloid modified polyvinyl alcohol with low viscosity and preparation method thereof |
| CN104558319A (en) * | 2013-10-22 | 2015-04-29 | 中国石油化工集团公司 | Method for improving forming of low-viscosity polyvinyl alcohol |
| CN109354641A (en) * | 2014-03-28 | 2019-02-19 | 辛色姆（英国）有限公司 | Prepare the application of the method, branched polymer and the polymer of branched polymer |
| CN111100222A (en) * | 2018-10-26 | 2020-05-05 | 中国石油化工股份有限公司 | Low-viscosity polyvinyl alcohol and preparation method thereof |
| CN111100230A (en) * | 2018-10-26 | 2020-05-05 | 中国石油化工股份有限公司 | Polyvinyl alcohol having excellent water solubility and method for producing same |
| CN111410706A (en) * | 2020-04-23 | 2020-07-14 | 安徽皖维高新材料股份有限公司 | Preparation method of polyvinyl alcohol with ultralow polymerization degree |
| CN111662401A (en) * | 2020-07-08 | 2020-09-15 | 安徽皖维高新材料股份有限公司 | Preparation method of polyvinyl alcohol with low polymerization degree |
| CN112545404A (en) * | 2020-12-08 | 2021-03-26 | 湖北魔洗高新材料制品有限公司 | Improved method for preparing PVA collodion cotton head with high-efficiency production |
| CN115260351A (en) * | 2022-01-11 | 2022-11-01 | 广安职业技术学院 | Method for preparing polyvinyl alcohol with polymerization degree of 80 by soap-free emulsion polymerization |
| CN115418145A (en) * | 2022-08-19 | 2022-12-02 | 复旦大学 | Water-based thermosetting coating based on polyvinyl alcohol resin with low alcoholysis degree and preparation method thereof |
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| CN101747459A (en) * | 2008-12-02 | 2010-06-23 | 卢金永 | Preparation method of dispersing agent of chemically modified polyvinyl alcohol |
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| EP1516889A1 (en) * | 2003-09-17 | 2005-03-23 | Kuraray Co., Ltd. | Polyvinyl alcohol based polymer and method of manufacturing the same |
| CN101054426A (en) * | 2007-04-27 | 2007-10-17 | 中北大学 | Method of preparing vinyl alcohol with low degree of polymerization |
| CN101177467A (en) * | 2007-11-28 | 2008-05-14 | 吴江市方霞企业信息咨询有限公司 | Method for preparing polyvinyl alcohol by vinyl acetate method |
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Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104558319A (en) * | 2013-10-22 | 2015-04-29 | 中国石油化工集团公司 | Method for improving forming of low-viscosity polyvinyl alcohol |
| CN104558319B (en) * | 2013-10-22 | 2017-12-26 | 中国石油化工集团公司 | A kind of method for improving the shaping of low viscosity polyvinyl alcohol |
| CN109354641A (en) * | 2014-03-28 | 2019-02-19 | 辛色姆（英国）有限公司 | Prepare the application of the method, branched polymer and the polymer of branched polymer |
| CN103897089A (en) * | 2014-04-01 | 2014-07-02 | 湖南省湘维有限公司 | Crystalloid modified polyvinyl alcohol with low viscosity and preparation method thereof |
| CN111100222B (en) * | 2018-10-26 | 2023-01-03 | 中国石油化工股份有限公司 | Low-viscosity polyvinyl alcohol and preparation method thereof |
| CN111100222A (en) * | 2018-10-26 | 2020-05-05 | 中国石油化工股份有限公司 | Low-viscosity polyvinyl alcohol and preparation method thereof |
| CN111100230A (en) * | 2018-10-26 | 2020-05-05 | 中国石油化工股份有限公司 | Polyvinyl alcohol having excellent water solubility and method for producing same |
| CN111410706A (en) * | 2020-04-23 | 2020-07-14 | 安徽皖维高新材料股份有限公司 | Preparation method of polyvinyl alcohol with ultralow polymerization degree |
| CN111662401A (en) * | 2020-07-08 | 2020-09-15 | 安徽皖维高新材料股份有限公司 | Preparation method of polyvinyl alcohol with low polymerization degree |
| CN112545404A (en) * | 2020-12-08 | 2021-03-26 | 湖北魔洗高新材料制品有限公司 | Improved method for preparing PVA collodion cotton head with high-efficiency production |
| CN112545404B (en) * | 2020-12-08 | 2022-05-17 | 湖北魔洗高新材料制品有限公司 | Improved method for preparing PVA collodion cotton head with high-efficiency production |
| CN115260351A (en) * | 2022-01-11 | 2022-11-01 | 广安职业技术学院 | Method for preparing polyvinyl alcohol with polymerization degree of 80 by soap-free emulsion polymerization |
| CN115260351B (en) * | 2022-01-11 | 2024-01-26 | 广安职业技术学院 | Method for preparing polyvinyl alcohol with polymerization degree of 80 by soap-free emulsion polymerization |
| CN115418145A (en) * | 2022-08-19 | 2022-12-02 | 复旦大学 | Water-based thermosetting coating based on polyvinyl alcohol resin with low alcoholysis degree and preparation method thereof |
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Application publication date: 20110629 |