Low-alcoholysis-degree polyvinyl acetate (PVA) continuous alcoholysis process

A technology of alcoholysis degree and alcoholysis, which is applied in the direction of chemical recycling, can solve the problems of wide distribution of alcoholysis degree, low production efficiency, high recycling cost, etc., and achieve the effect of reducing recycling cost, reducing neutralization cost and reducing usage

Inactive Publication Date: 2011-07-20
云南煤化工应用技术研究院有限公司 +1
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  • Summary
  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

However, the "belt method" has many disadvantages at the same time: firstly, the reaction temperature is generally lower than 50°C, and the reactants cannot be stirred during the reaction, so the reaction rate is very low; secondly, due to the limitation of the belt size and the low reaction rate The reason is that the production efficiency of the "belt method" is very lo

Method used

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  • Low-alcoholysis-degree polyvinyl acetate (PVA) continuous alcoholysis process
  • Low-alcoholysis-degree polyvinyl acetate (PVA) continuous alcoholysis process

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Embodiment 1

[0024] PVAc methanol solution and NaOH methanol solution are charged into tank 1 and tank 2 respectively, and pass through metering pump 3 and metering pump 4 respectively. Mass concentration is that the PVAc methanol solution of 30% is that the NaOH methanol solution of 0.5% is added in the prereactor 5 with the flow rate of 20kg / h and concentration with 8.4L / h, and the prereactor 5 temperature is 55 ℃, stirs and mixes 0.6 minute, After mixing evenly, add it to the reactive twin-screw extruder 6 for alcoholysis reaction. The temperature of the extruded product at the head of the twin-screw extruder 6 is 70°C, the residence time is 3 minutes, and the extruded product is white granular solid, then quickly put the extruded product into 0.7% acetic acid, stir and wash for 3-5 minutes, separate and dry to obtain PVA particles. The degree of polymerization of polyvinyl alcohol (PVA) is 200-5000. After testing, the degree of alcoholysis of the produced PVA granules is 88%, among wh...

Embodiment 2

[0026] Be that the PVAc methanol solution that mass concentration is 50% with the flow rate of 20kg / h and the NaOH methanol solution that concentration is 1.2% add in the prereactor 5 with the flow rate of 5.4L / h respectively, the prereactor 5 temperature is 55 ℃, stirring Mix for 2.5 minutes, mix evenly and add to reactive twin-screw extruder 6 to carry out alcoholysis reaction. It is a white granular solid, and the extruded product is quickly put into 0.7% acetic acid, stirred and washed for 3-5 minutes, separated and dried to obtain PVA particles. The degree of polymerization of polyvinyl alcohol (PVA) is 200-5000. After testing, the degree of alcoholysis of the produced PVA particles is 86%.

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Abstract

The invention discloses a novel polyvinyl acetate (PVA) continuous alcoholysis process. The process comprises the following steps of: adding polyvinyl acetate (PVAc) methanol solution and catalyst sodium hydroxide (NaOH) methanol solution into a prereactor according to a fixed amount and mixing quickly and uniformly; adding mixed solution into a reaction type double-screw extruder to perform an alcoholysis reaction; extruding from a machine head mould to obtain white granular products; and performing treatment of acid neutralization, drying and the like to obtain the final product. The process has the advantages of high reaction speed, high reaction capacity, controllable retention time of reactants, narrower retention time distribution, capability of continuous production and the like. Compared with the traditional process, the process also has the advantages of reducing the using amount of a solvent methanol and a catalyst NaOH, along with low recovery cost of the solvent and alkali and environmental friendliness. The low-alcoholysis-degree PVA product obtained by the process has narrow alcoholysis-degree distribution and stable properties.

Description

technical field [0001] The invention relates to a high molecular polymer production process, namely a continuous alcoholysis process for PVA with low alcoholysis degree. Background technique [0002] PVA is an important synthetic material, its performance is between rubber and plastic, and it is one of the few water-soluble polymers found so far. It is mainly used in the production of civilian clothing, industrial cord fabrics, filter cloths, Fishing nets, coatings, adhesives, emulsifiers, aviation and automotive safety glass, etc. According to the degree of alcoholysis, PVA can be divided into PVA with low degree of alcoholysis and PVA with high degree of alcoholysis. Low degree of alcoholysis PVA has high surface activity and low surface tension, and is widely used in PVC polymerization, rubber emulsion polymerization, emulsification technology, electronics industry and membrane material manufacturing. [0003] The traditional process generally adopts the "belt method" t...

Claims

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Application Information

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IPC IPC(8): C08F116/06C08F8/00C08F118/08
CPCY02P20/584
Inventor 尹伟杜丽梅贾朝阳娄晓鸣杨魁李侠张国强何振鹏贾海峰
Owner 云南煤化工应用技术研究院有限公司
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