Polyester hyperdispersant and preparation thereof as well as preparation method of isocyanate

Abstract

The invention provides a polyester hyperdispersant and preparation thereof as well as a preparation method of isocyanate. The polyester hyperdispersant provided by the invention has the following structural formula (I): (the formula (I) is as shown in the description), wherein in the formula (I), R1 is the residue of diisocyanate with -NCO removed or the residue of polyisocyanate with -NCO removed, R2 is the residue of single-end hydroxyl polyethylene oxide with terminal hydroxyl removed, R3 is the residue of amino acid with -NH2 removed, and the amino acid comprises at least one chain segmentcontaining -COOH and at least one chain segment containing -NH2; and in the formula (I), m is more than 0 and less than or equal to 9, and n is more than 0 and less than or equal to 9. The polyesterhyperdispersant provided by the invention is introduced in a salification process in preparation of the isocyanate, so that the agglomeration phenomenon can be avoided, the flowability of a diamine hydrochloride solution is improved, and the production efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of isocyanate preparation, in particular to a polyester hyperdispersant and a preparation method thereof, and also to a method for preparing isocyanate using the polyester hyperdispersant. Background technique [0002] Aliphatic and cycloaliphatic diisocyanate (ADI) has become the research focus of major polyurethane companies and scientific research institutions around the world. Its products are widely used in coatings, car paints, Adhesives and medical materials and other fields. [0003] At present, the main way to prepare isocyanate is liquid phase phosgenation. The preparation of isocyanate by liquid phase phosgenation can be divided into cold and hot phosgenation and salt-forming phosgenation (referred to as salt-forming method). The cold and hot phosgenation method is to prepare the corresponding isocyanate through two stages of cold reaction and thermal reaction between primary amine and phosgene,...

AI Technical Summary

Problems solved by technology

Although high temperature and pressure can reduce the viscosity of hydrochloride and improve the conversion rate of salt formation and space-time efficiency, there are two defects: on the one hand, it is only suitable for diamines with high stability at high temperature, and it will seriously affect the salt formation and The color number of the photochemical solution; on the other hand, the salt formation rate is extremely fast at high temperature, so the heat transfer of the reactor and the wrapping of diamine should be considered

However, although this method can reduce the formation of by-products at low temperature and low concentration, the space-time yield is not high, and a large amount of solvent needs to be removed by distillation, which reduces its economical efficiency.

[0006] In summary, the main factor limiting the industrialization of the salt-forming liquid-phase phosgenation method is the low salt-forming concentration of the raw material diamine, which leads to the inability to improve the space-time benefit and economic benefit

In particular, due to the small molecular weight of short-chain aliphatic or alicyclic diamines in the salt-forming process, the viscosity of the obtained hydrochloride slurry increases rapidly, which brings about unfavorable conditions such as stirring, dispersing, and heat transfer difficulties, making it impossible to achieve higher concentration

For example, in the salt-forming process, if the concentration of diamine in the inert solvent is set to 6-10%, then the organic solvent in which the raw material amine is dissolved is mixed with hydrogen chloride gas, as the reaction proceeds, the hydrochloride The viscosity of the slurry rises rapidly. In the later stage of the reaction, the hydrochloride will form agglomerates on the bottom and wall of the kettle, and it is difficult to disperse it by stirring, resulting in a decrease in production efficiency.

[0007] Therefore, it is necessary to develop a new method for the preparation of isocyanate by salt-forming liquid phase phosgenation to solve the disadvantages of hydrochloride agglomeration, difficulty in dispersing, and low production efficiency.

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