Process for recovering high-purity N-methyl formamide from waste stripping solution

A technology of methylformamide and stripping solution, applied in the separation/purification of carboxylic acid amide, organic chemistry, etc., can solve the problems of limited use, difficulty in recovering high-purity products, low product quality, etc., and achieve negative impact and considerable economic value , The effect of high product yield

Active Publication Date: 2019-07-05
XINZHONGTIAN ENVIRONMENTAL PROTECTION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use effect of this group of solvents is good after mixing, and the industrial usage has been increasing, but the price is high, and it is difficult to recover high-purity products. If the waste liquid formed after use is directly discharged, it will cause environmental pollution and cause a great waste of resources.
[0003] The existing technology for recovering stripping liquid is mainly based on distillation technology, but what is recovered is often a mixed solvent, the product quality is low, and the use value is relatively low, so its use is greatly restricted
For the recovery of high-purity products of NMF and MDG, the group of waste stripping liquids, traditional r...

Method used

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  • Process for recovering high-purity N-methyl formamide from waste stripping solution

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] A kind of technique that reclaims high-purity N-methylformamide from waste stripping solution, its flow chart sees figure 1 shown, including the following steps:

[0022] (1) rectification: carry out rectification in the lightening rectification tower, the stripping liquid rectification of waste N-methylformamide and diethylene glycol methyl ether obtains the NMF crude product of mass concentration 80%;

[0023] (2) Melting crystallization: using a falling film crystallizer, use a chilled water control system to control the system temperature to -10°C~0°C, and distribute the molten NMF crude product at -10°C~-5°C from the feed liquid at the upper part of the crystallizer The device flows down along the inner wall of the crystallization tube, the frozen water and the molten material are kept circulating, and the temperature is lowered to -15~-10°C at a rate of 1°C / h to crystallize NMF, and the uncrystallized raffinate is collected and reused for rectification process; ...

Embodiment 2

[0029] A kind of technique that reclaims high-purity N-methylformamide from waste stripping solution, its flow chart sees figure 1 shown, including the following steps:

[0030] (1) rectification: carry out rectification in the lightening rectification tower, the stripping liquid rectification of waste N-methylformamide and diethylene glycol methyl ether obtains the NMF crude product of mass concentration 90%;

[0031] (2) Melting crystallization: using a falling film crystallizer, use a chilled water control system to control the system temperature to -10°C~0°C, and distribute the molten NMF crude product at -10°C~-5°C from the feed liquid at the upper part of the crystallizer The device flows down along the inner wall of the crystallization tube, the frozen water and the molten material are kept circulating, and the temperature is lowered to -15~-10°C at a rate of 5°C / h to crystallize NMF, and the uncrystallized raffinate is collected and reused for rectification process; ...

Embodiment 3

[0037] A kind of technique that reclaims high-purity N-methylformamide from waste stripping solution, its flow chart sees figure 1 shown, including the following steps:

[0038] (1) rectification: carry out rectification in the lightening rectification tower, the stripping liquid rectification of waste N-methylformamide and diethylene glycol methyl ether obtains the NMF crude product of mass concentration 85%;

[0039] (2) Melting crystallization: using a falling film crystallizer, use a chilled water control system to control the system temperature to -10°C~0°C, and distribute the molten NMF crude product at -10°C~-5°C from the feed liquid at the upper part of the crystallizer The device flows down along the inner wall of the crystallization tube, the frozen water and the molten material are kept circulating, and the temperature is lowered to -15~-10°C at a rate of 3°C / h to crystallize NMF, and the uncrystallized raffinate is collected and reused for rectification process; ...

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Abstract

The invention relates to the technical field of waste stripping solution recovery, and provides a process for recovering high-purity N-methyl formamide from a waste stripping solution. The process includes rectifying the waste stripping solution containing N-methyl formamide and diethylene glycol methyl ether to obtain a NMF crude product having a mass concentration of 80-90%; repeating 1-3 timesof melting and crystallization; performing partial melting, melting, melt liquid collection and cooling for crystallization to obtain high-purity NMF. A technique combining melting and crystallizationwith rectification is adopted so that a problem that high-purity NMF cannot be obtained through recovery is solved, and the process has advantages of simple procedures, low investment, short period,a high yield and a low cost. The obtained high-purity NMF is high in purity which can be electronic chemical purity that is 99.99%, thus overcoming a problem that purity of a product of rectificationonly can reach 90%.

Description

technical field [0001] The invention relates to the technical field of recovery of waste stripping liquid, in particular to a process for recovering high-purity N-methylformamide from waste stripping liquid. Background technique [0002] The rapid development of the domestic electronics manufacturing industry has greatly increased the use of electronic chemicals such as strippers. In the production process of electronic components such as liquid crystal display panels and semiconductor integrated circuits, it is necessary to use a stripping solution to remove the photoresist coated on the microcircuit protection area as a mask. The stripping solution used is usually made of organic amine and polar organic A mixture of solvents, a mixture of N-methylformamide (NMF) and diethylene glycol methyl ether (MDG) is one of them. This group of solvents has a good effect after mixing, and the industrial usage has been increasing. However, the price is high, and it is difficult to reco...

Claims

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Application Information

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IPC IPC(8): C07C231/24
CPCC07C231/24C07C233/03
Inventor 何睿鸣毛小英阳杨林辉荣左姣陈国平
Owner XINZHONGTIAN ENVIRONMENTAL PROTECTION
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