Preparation method for hexamethylene diisocyanate biruet

A technology of hexamethylene diisocyanate and biuret is applied in the field of preparing HDI biuret with low free isocyanate monomer, which can solve the problem of unstable load of thin film evaporator, low yield of biuret structure and continuous industrialization. Not good and other problems, to achieve the effect of low free isocyanate monomer content, reduced scaling phenomenon, and easy control of the reaction

Active Publication Date: 2012-10-03
SOUTH CHINA UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] U.S. Patent US3124605 discloses a method for preparing HDI biuret by dripping method. The HDI biuret obtained by this method is transparent in color and has good compatibility with hydroxyl components, but there are still the following disadvantages: (1) Reaction system It is a heterogeneous reaction, the efficiency is low, and the reaction is not easy to control
Since water and diisocyanate monomers are difficult to dissolve in each other, when water is added dropwise to the two-phase interface, it cannot meet the requirement of a large excess of actual diisocyanate, and the reaction of this heterogeneous system will generate a large amount of insoluble white polyurea, and further It affects the occurrence of the main reaction, and the yield of the biuret structure is low
(2) The loss of water is particularly large
However, due to the introduction of high boiling point extractant and extraction entrainer, the load of the thin film evaporator is unstable, the continuity of industrialization is not good, the product quality is unstable, and the performance of the prepared coating film is also affected.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] A preparation method of hexamethylene diisocyanate biuret, which comprises the following steps:

[0035] (1) The azeotrope formed by mixing deionized water and cyclohexanone is heated to 30°C, kept warm, and set aside; the polar aprotic solvent cyclohexanone accounts for 10% of the azeotrope;

[0036] (2) Under the protection of nitrogen, first put the hexamethylene diisocyanate monomer into the reaction vessel and maintain the temperature at 90°C; add the azeotrope described in step (1) dropwise to the reaction via a peristaltic pump In the container, the dropping rate is 0.05g / min; after the dropping, continue to heat up to 110°C under stirring and react for 1h; then lower the temperature to below 35°C, cool and discharge the material to obtain hexamethylene diisocyanate biuret; The molar ratio of hexamethylene diisocyanate monomer to deionized water is 4:1;

[0037] (3) The hexamethylene diisocyanate biuret obtained in step (2) enters the first stage separation device and ...

Embodiment 2

[0039] A preparation method of hexamethylene diisocyanate biuret, which comprises the following steps:

[0040] (1) The azeotrope formed by mixing deionized water with polar aprotic solvents N,N-dimethylformamide and N,N-dimethylacetamide is heated to 100°C, kept warm, and set aside; The polar aprotic solvents N,N-dimethylformamide and N,N-dimethylacetamide (1:1) account for 70% of the azeotrope by mass;

[0041] (2) Under the protection of nitrogen, first put the hexamethylene diisocyanate monomer into the reaction vessel and maintain the temperature at 140°C; add the azeotrope described in step (1) dropwise to the reaction via a peristaltic pump In the container, the dropping rate is 0.20g / min; after the dropping, continue to heat up to 150°C for 4h under stirring; then lower the temperature to below 40°C, cool and discharge the HDI biuret; the hexamethylene group The molar ratio of diisocyanate monomer to deionized water is 10:1;

[0042] (3) The hexamethylene diisocyanate biure...

Embodiment 3

[0044] A preparation method of hexamethylene diisocyanate biuret, which comprises the following steps:

[0045] (1) The azeotrope formed by mixing deionized water and polar aprotic solvent 3-methyl-2-butanone, ethylene glycol ethyl ether acetate and ethylene glycol butyl ether acetate is heated to 70°C and kept warm, To be used; the polar aprotic solvent 3-methyl-2-butanone, ethylene glycol ethyl ether acetate and ethylene glycol butyl ether acetate (the volume ratio of the three is 1:1:2) accounts for the azeotrope The mass percentage of the material is 35%;

[0046] (2) Under the protection of nitrogen, first put the hexamethylene diisocyanate monomer into the reaction vessel and maintain the temperature at 120°C; add the azeotrope described in step (1) dropwise to the reaction via a peristaltic pump In the container, the dropping rate is 0.16g / min; after the dropping, continue to heat up to 200°C for 3h under stirring; then cool to below 40°C, cool and discharge the HDI biuret;...

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Abstract

The invention discloses a preparation method for hexamethylene diisocyanate biruet, according to the method, azeotrope formed by a mixture of deionized water and a polar aprotic solvent is heated into a temperature of 30-100 DEG C; hexamethylene diisocyanate monomer is put into a reactor, and the temperature is maintained at 90-140 DEG C; the azeotrope is dropped into the reactor at a dropping speed of 0.05-0.20g / min; the temperature is increased into 110-150 DEG C in a mixing state, and the azeotrope is reacted for 1-4h; the temperature is reduced below 40 DEG C for cooling and discharging; and the discharging material enters into a separation device for separating a solvent and hexamethylene diisocyanate biruet ingredient, and a solid content of hexamethylene diisocyanate biruet ingredient is adjusted between 50 percent and 90 percent by a diluent. According to the preparation method, new solvent is not needed for addition, production formula and operation process are not required to be changed, only the monomer of isocyanate and water are added to realize continuous production, and the real clean production is realized via zero-release.

Description

Technical field [0001] The present invention relates to a preparation method of hexamethylene diisocyanate (HDI) biuret, which is the most important polyisocyanate prepolymer in high-decorative polyurethane coatings for external use. Specifically, it is prepared by the dripping method of water azeotrope to prepare low free The HDI biuret method of isocyanate monomer. Background technique [0002] US Patent No. 3124605 discloses a method for preparing HDI biuret by dripping water. The HDI biuret obtained by this method is transparent in color and has good compatibility with hydroxyl components, but still has the following shortcomings: (1) Reaction system It is a heterogeneous reaction with low efficiency and the reaction is difficult to control. Since water and diisocyanate monomers are difficult to dissolve each other, when water drops are added to the two-phase interface, it cannot meet the requirement of a large excess of diisocyanate, and the reaction of this heterogeneous s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G18/79C07C275/62C07C273/18C09D175/04
Inventor 张心亚张鑫芳何勇黄洪殷代武王代民曹树潮梅慈云陈焕钦
Owner SOUTH CHINA UNIV OF TECH
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