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Separation process of free monomer for polyurethane curing agent

The technology of a polyurethane curing agent and a separation method is applied in the field of separation and purification of isocyanate monomers, which can solve the problems of high energy consumption and narrow practicability, and achieve the effect of simple separation process and wide adaptability.

Inactive Publication Date: 2003-01-08
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] Aiming at the shortcomings of the prior art, the present invention provides an efficient and economical method for separating free monomers in polyurethane curing agents, to separate toxic free isocyanate monomers in polyurethane curing agents, and to overcome the narrow practicality and energy consumption of existing processes. High disadvantage

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0024] Adopting 3mol of toluene diisocyanate (TDI) and 1mol trimethylolpropane (TMP) to synthesize solid content is 45%, and free TDI content is the polyurethane coating curing agent of 7%, adopts xylene and butyl acetate as solvent; The curing agent is degassed at 160°C under normal pressure, then add 20% of the mixture of diethylene glycol butyl ether acetate and S-150 solvent, carry out molecular distillation at 180°C and 140Pa to obtain the product as solid content 98%, TDI content of 0.70% polyurethane curing agent. And compare the experimental results with the vacuum distillation at 180°C and 100 Pa for 30 minutes, as shown in Table 1. Table 1 shows that this process does not affect the physical properties of the curing agent while reducing the free TDI monomer.

[0025] project

[0026] Adopt 1mol polyester diol (relative molecular mass is 1000, hydroxyl content 3.30%) and the TDI reaction synthesis polyurethane prepolymer of 1.6mol, its relative molecular m...

example 3

[0028] The TDI trimer produced by a paint factory has a solid content of 45% and a residual free TDI monomer content of 2.5%. The manufacturer provided us with 500 kg of curing agent, and we processed the curing agent at 160°C and 1000Pa. Primary degassing, then adding 10% mixture of dibasic acid ester (DBE) and dibutyl phthalate, molecular distillation at 200°C, 120Pa to obtain a solid content of 99% and a free monomer content of 0.5% Diluted with xylene and butyl acetate, it is used as a curing agent for hydroxy alkyd resin. The hardness and adhesion of the coating film have not changed much compared with the original paint, while the impact resistance and gloss of the coating film have been compared. Great improvement, no free TDI monomer was detected in the construction environment.

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Abstract

A method of separation of the dissociative monomer in the polyamido ester solidifying agent, incldues the following steps: (1) get rid of the solvent in the solidifying agent; (2) add the extracting agent and the extractive smuggling agent to the solidifying agent, then make the molecular distillation and the distilled leaving is the solidifying agent; (3) dilute the solidifying agnet; compared with the chemical-reaction method and the vacuum-distilling method, this method can reduce the content of the dissociative monomer in the polyamido ester, at the same time it can't augment the relative molecular weight and the distribution of the relative molecular weight, and reduce the compatibility of the solidifying agent with the hydroxy ester; and the gained solid content can be optionally adjusted and even reach the weight of 80-100 % of the high solid content.

Description

technical field [0001] The invention relates to the separation and purification of high-viscosity heat-sensitive polymers, and is especially suitable for the separation and purification of residual free and toxic isocyanate monomers in polyurethane curing agents for coatings. Background technique [0002] Polyurethane coating film has beautiful appearance, high hardness, corrosion resistance and chemical resistance, and is one of the coating varieties with the best comprehensive performance. [0003] According to modern environmental protection requirements, polyurethane coatings must solve two technical problems. One is to increase the solid content and minimize the solvent content. The second is to reduce the free diisocyanate content in polyurethane curing agents, that is, to develop non-toxic curing agents. [0004] At present, my country's polyurethane curing agent has a single variety, low solid content, and high residual free diisocyanate monomer content (high toxici...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J11/02
Inventor 瞿金清黄洪陈焕钦
Owner SOUTH CHINA UNIV OF TECH
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