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Method for continuously manufacturing toluene di-isocyanate

A technology of toluene diisocyanate and its manufacturing method, applied in the direction of urethane preparation, organic chemistry, etc., can solve the problems of increased side reactions, equipment abrasion, slow rate of isocyanate, etc., to reduce the amount of production, increase energy consumption, reduce Abrasive effect

Inactive Publication Date: 2010-03-17
SEDIN ENG +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the hydrogen chloride content is generally high in the recovered phosgene, reaching about 0.5% (mass fraction). If it is directly used in the phosgenation reaction, more organic amine hydrochloride will be produced.
This is unfavorable to the continuous and stable production of isocyanate: on the one hand, the amine hydrochloride is hard and will cause abrasion to the equipment; on the other hand, the amine hydrochloride continues to react to form isocyanate at a slow rate, and the temperature needs to be raised to speed up the reaction rate , which increases the extent to which side reactions occur
If the hydrogen chloride concentration in the recovered phosgene is reduced to a lower range to reduce the generation of organic amine hydrochloride, it will increase the energy consumption of the phosgene recovery system

Method used

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  • Method for continuously manufacturing toluene di-isocyanate
  • Method for continuously manufacturing toluene di-isocyanate
  • Method for continuously manufacturing toluene di-isocyanate

Examples

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Embodiment 1

[0043] This embodiment is a continuous production process of toluene diisocyanate (TDI) before improvement, specifically, toluene diamine and phosgene are only mixed in one step, and a jet reactor is used as the phosgenation reactor.

[0044]After heating the organic inert solvent o-dichlorobenzene (ODCB), dilute m-toluenediamine (m-TDA) to a mass concentration of 20%, and control the amount of heating so that the temperature of the m-toluenediamine solution is around 100-140°C. Similarly, fresh phosgene and recycled phosgene are made into a solution with a mass concentration of 40% by using heated o-dichlorobenzene, and the temperature is controlled at 80-100° C. The phosgene solution contains 0.44% hydrogen chloride in mass fraction. Control the molar ratio of amino group and phosgene in the toluenediamine to be 1:3, adjust the reaction temperature to be 100-110° C., and the absolute reaction pressure to be 1.5-1.8 MPa. The crude product of the phosgenation reaction is passe...

Embodiment 2

[0046] A continuous manufacturing method of toluene diisocyanate, comprising the steps of:

[0047] (1) After heating the organic inert solvent o-dichlorobenzene (ODCB), dilute m-toluenediamine (m-TDA) to a mass concentration of 20%, and control the amount of heating to dissolve the m-toluenediamine solution. In the phosgene refining tower, fresh phosgene and non-condensable gas from the top of the phosgenation reaction flasher and degassing tower are absorbed into 35% to 40% phosgene ortho-dichlorobenzene with heated o-dichlorobenzene Benzene solution, wherein the hydrogen chloride mass fraction is less than 0.1%, its temperature is controlled at 40-50 ° C, according to the molar ratio of amino group and phosgene in m-toluenediamine is 1: 2, the o-dichlorobenzene solution of m-toluenediamine Mix and react with phosgene o-dichlorobenzene solution with a mass content of less than 0.1% hydrogen chloride in a jet mixer, the reaction temperature is 50-60°C, and the absolute pressu...

Embodiment 3

[0052] A continuous manufacturing method of toluene diisocyanate, comprising the steps of:

[0053] (1) With an impingement flow mixer, the chlorobenzene solution of 5% toluenediamine with a mass concentration and the phosgene with a mass concentration of 5% to 10% that contain a mass fraction of 0.1% hydrogen chloride at a temperature of 40 to 50°C The chlorobenzene solution is pre-mixed and reacted, the reaction temperature is 70-80°C, the absolute reaction pressure is 0.5-0.7MPa, and the average residence time of the material in the impinging flow mixer does not exceed 10s; in the impinging flow mixer, toluene diamine The molar ratio of amino group and phosgene is 1:1.5;

[0054] (2) Input the reacted mixture into the high-shear reactor, and continue to add the low-temperature 140-160° C. Continue to mix and react in the phosgene chlorobenzene solution with a mass concentration of 0.5% hydrogen chloride of 40% to 45%, and control the reaction temperature to 130 to 140°C, t...

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Abstract

The invention discloses a method for continuously manufacturing toluene di-dsocyanate, comprising the following steps: (1) premixing a toluenediamine inert solvent solution with a phosgene inert solvent solution containing a hydrogen chloride with a mass fraction lower than 0.1 percent by a premixer and generating reaction; (2) importing the reacted mixture into a high shear reactor and refillingthe phosgene inert solvent solution containing the hydrogen chloride with the mass fraction lower than 0.5 percent to continue mixing and generating reaction; (3) leading materials in an outlet of thehigh shear reactor into detention equipment, continuing reacting at a temperature of 90-200 DEG C and an absolute pressure of 0.3-1.8 MPa until the solution turns transparent and a crude toluene di-isocyanatel is generated. The method for continuously manufacturing toluene di-dsocyanate is realized by mixing the phosgene with hydrogen chlorides in different contents with the toluenediamine step by step, thereby reducing the generation amount of low amine hydrochloride, improving the yield of the product toluene di-isocyanate and avoiding the addition of the energy consumption in refining phosgene recovering.

Description

technical field [0001] The present invention relates to a kind of continuous production method of toluene diisocyanate. Background technique [0002] Polyurethane materials have the characteristics of convenient modification, easy processing and molding, and simple construction, and are extremely widely used in various fields such as heat insulation, shockproof, sound insulation, cushion materials, packaging, and light structures. Isocyanate is an important monomer raw material in the polyurethane industry. The method of preparing isocyanate by phosgenation of primary amine has been reported many times in patents, and has been carried out on a large scale in industry, especially aromatic isocyanate TDI (toluene diisocyanate), The reactions that may occur during its preparation are as follows: [0003] [0004] [0005] TDI+urea→TDI biuret (7) [0006] TDI+TDI biuret → polyurea (8) [0007] Reaction (1), (2) is the main reaction to generate isocyanate, and the rest a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C265/14C07C263/04
Inventor 闫少伟李韡潘国平张金利李改英徐双庆崔晓曦辛峰韩优杨锦
Owner SEDIN ENG
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