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Method for preparing light-colored TDI (toluene diisocynate) based polyisocyanate composition curing agent with stable storage color number

A technology of toluene diisocyanate and polyisocyanate, which is applied in the field of polyisocyanate curing agent production, can solve the problems of making a decisive contribution and not pointing out the increase of color number, and achieve the effect of storage stability

Active Publication Date: 2019-08-02
WANHUA CHEM GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] Although these very complicated methods can produce higher purity and lighter color toluene diisocyanate and its polyisocyanate composition curing agent, it is still not pointed out which secondary components make a decisive contribution to the color number growth of the polyisocyanate composition storage process

Method used

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  • Method for preparing light-colored TDI (toluene diisocynate) based polyisocyanate composition curing agent with stable storage color number
  • Method for preparing light-colored TDI (toluene diisocynate) based polyisocyanate composition curing agent with stable storage color number

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] First, rectify the toluene diisocyanate product whose proportion of 2,4-toluene diisocyanate is 80%. During the rectification process, the temperature of the tower kettle is controlled at 155°C, the absolute pressure of the rectification tower is 4kPa, and the pressure drop is 3kPa. The temperature of the top condenser is 20°C, the cryogenic temperature is -3°C, and the reflux ratio is 4:1. A toluene diisocyanate raw material with a dichloroimine content of 3 ppm was obtained.

[0046] Trimethylolpropane was added dropwise to 7 times the mass of the above purified toluene diisocyanate fraction. The material reaction temperature is controlled at 60° C., and the reaction time is 16 hours; after the reaction is completed, the aging operation is performed, and the aging temperature is controlled at 70° C., and the aging time is 1 hour to obtain a prepolymer reaction liquid. Excess toluene diisocyanate monomer is removed by short-range thin film evaporation, the separation...

Embodiment 2

[0048] First, rectify the toluene diisocyanate product whose proportion of 2,4-toluene diisocyanate is 80%. During the rectification process, the temperature of the tower kettle is controlled at 155°C, the absolute pressure of the rectification tower is 4kPa, and the pressure drop is 3kPa. The temperature of the top condenser is 20°C, the cryogenic temperature is -3°C, and the reflux ratio is 4:1. A toluene diisocyanate raw material with a dichloroimine content of 3 ppm was obtained.

[0049] Prepare a mixture of trimethylolpropane and propylene glycol with a mass ratio of 4:1. Then the above mixture was added dropwise to 7 times the mass of the above purified toluene diisocyanate component. The material reaction temperature is controlled at 60° C., and the reaction time is 16 hours; after the reaction is completed, the aging operation is performed, and the aging temperature is controlled at 70° C., and the aging time is 1 hour to obtain a prepolymer reaction liquid. Excess...

Embodiment 3

[0051] First, rectify the toluene diisocyanate product whose proportion of 2,4-toluene diisocyanate is 80%. During the rectification process, the temperature of the tower kettle is controlled at 165°C, the absolute pressure of the rectification tower is 2kPa, and the pressure drop is 3kPa. The temperature of the top condenser is 20°C, the cryogenic temperature is -3°C, and the reflux ratio is 5:1. A toluene diisocyanate raw material with a dichloroimine content of 1.8 ppm was obtained.

[0052] Prepare a mixture of trimethylolpropane and diethylene glycol, the mass ratio of the two is 3:1. Then the above mixture was added dropwise to 6 times the mass of the above purified toluene diisocyanate component. The reaction temperature of the material is controlled at 55° C., and the reaction time is 18 hours; after the reaction is completed, the aging operation is performed, and the aging temperature is controlled at 65° C., and the aging time is 2 hours to obtain a prepolymer reac...

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Abstract

The invention provides a preparation method of a light-colored TDI (toluene diisocynate) based polyisocyanate composition curing agent with stable storage color number. The method comprises steps as follows: a) TDI is purified, and the content of dichloroimide substances is controlled to be not higher than 3 ppm; b) excessive TDI with the content of dichloramine not higher than 3 ppm and trimethylolpropane or a mixture of trimethylolpropane and small molecular dibasic alcohol are subjected to a reaction, a reaction liquid is prepared, and the polyisocyanate composition curing agent is obtainedthrough short-range film evaporation and solvent dilution. Composition obtained with the method can be used for a coating curing agent, the curing agent has the APHA color number smaller than 15 andis stable to store.

Description

technical field [0001] The invention relates to a method for preparing a curing agent for a toluene diisocyanate-based polyisocyanate composition with light color and stable storage color number, belonging to the field of polyisocyanate curing agent production. Background technique [0002] The toluene diisocyanate-based polyisocyanate composition is generally used as a coating curing agent, and has a wide range of applications in the fields of wood coatings and industrial coatings. Its preparation principle is based on the prepolymerization reaction of toluene diisocyanate (TDI) component and small molecule polyol to obtain the prepolymer reaction solution of terminal NCO group, and then remove the diisocyanate monomer and dilute to obtain the product. At present, the market demand for toluene diisocyanate-based polyisocyanate combined curing agent based on trimethylolpropane and its mixture with small molecule polyols is large, accounting for about 30% of the polyurethane ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G18/76C08G18/32
CPCC08G18/3206C08G18/7621
Inventor 金振宇彭华庆王艳丽张坤张宏科
Owner WANHUA CHEM GRP CO LTD
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