Preparation method of diphenylmethane series diamine and polyamine with low macromolecular impurity content

Abstract

The invention relates to a preparation method of diphenylmethane series diamine and polyamine with low macromolecular impurity content. According to the method, the content ratio of monomer formaldehyde in formaldehyde is controlled in 40-60wt% before aniline and the formaldehyde are reacted under the condition of an acid catalyst. Before the formaldehyde and the aniline or aniline hydrochloride are mixed, a state of formaldehyde water solution is changed, low-polymerized formaldehyde in water solution is depolymerized, the content of the monomer formaldehyde in the water solution is controlled to reach a more favorable range, macromolecular resin solid impurities generated in condensation reaction are decreased, blocking caused by aggregation of macromolecular polymers in a device and a pipeline is remarkable relieved in medium and long term continuous production processes of DAM is obviously relieved, and the content of macromolecular impurities in the DAM is decreased.

Description

technical field [0001] The invention belongs to the technical field of DAM preparation, and relates to a production method of higher-quality diphenylmethane series diamines and polyamines, in particular to a preparation of diphenylmethane series diamines and polyamines (DAM) with low macromolecule impurity content method. Background technique [0002] The preparation process of DAM is generally known, and it is conventionally carried out by reacting aniline and formaldehyde in the presence of an acidic catalyst in a continuous, semi-continuous or discontinuous process. This method is described in many patents and publications (see, for example, HJ. Twitchett, Chem. Soc. Rev. 3 (2), 209 pages (1974), M, V, Moore's Kirk-othmer Encycle. Chem. Technol. Third Edition, New York, 2, pp. 338-348 (1978)). In industrial production, aniline is usually reacted with hydrochloric acid first, and then formaldehyde is added to the reaction system to obtain DAM hydrochloride under acid-cat...

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Problems solved by technology

[0006] In the process of continuous production of DAM in large-scale industrial equipment, macromolecular resin-like solid substances are easily produced during the reaction process of acid-catalyzed aniline and formaldehyde. On the other hand, it will be brought into the product DAM, affecting the quality of DAM

In fact, it has been recognized that the above-mentioned solid product is mainly due to poor mechanical mixing of formaldehyde in the reaction process, and there is a local excess of formaldehyde relative to aniline, thereby producing a macromolecular resinous substance, which is difficult to dissolve in solvents such as aniline and hydrochloric acid. Blockage of equipment pipelines due to the presence of solid forms

[0007] In this regard, many patents at home and abroad have mentioned related technologies to improve this problem from the perspective of mechanical stirring or the reduction of the total proportion of formaldehyde to aniline. For example, EP2486975 (A1) discloses the use of a special mixer reactor in the preparation of MDA. , CN101279923A patent improved the mixing reaction equipment, CN106458844A patent carried out formaldehyde feeding operation and control improvement during start-up and shutdown, etc., the above-mentioned method controlled the generation of macromolecular resin impurities to a certain extent, and solved the problem of short-term and medium-term solid impurities. The problem of equipment blockage, but this kind of excessive polymerization product that is still continuously generated accumulates in the system in the form of solid suspension during the high-load and long-term operation of the production device, which will still affect the long-term continuous and smooth operation of the device and the quality of the product DAM make an impact

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