Preparation method of low-dissociation high-intermiscibility polyurethane curing agent

Abstract

The invention discloses a preparation method of a low-dissociation high-intermiscibility polyurethane curing agent. The method is as below: preparing the following raw materials by weight: (A) 40-70 parts of toluene diisocyanate or a mixture of two toluene diisocyanates, (B) 23-27 parts of a ester solvent with boiling point no higher than 200 DEG C, (C) 5-20 parts of trimethylol propane, (D) 1-20 parts of composite polyol ethers, (E) 0.1-0.2 part of an isocyanate trimerization catalyst and (F) 0.1-0.3 part of an isocyanate trimerization inhibitor; carrying out reactions at different temperature conditions to remove most dissociated toluene diisocyanate monomers; and then carrying out trimerization on the dissociated monomers under the effect of the catalyst to remove remaining dissociated toluene diisocyanate monomers. The prepared curing agent products has content of dissociated toluene diisocyanate reaching requirements of the latest national standard, and has the advantages of high solid content, low viscosity, good compatibility, good stability and unchanged paint film performance after paint preparation.

Description

technical field [0001] The invention relates to a preparation method of a polyurethane curing agent with low free and high compatibility. Background technique [0002] Among the high-solid 75 series polyurethane curing agents commonly used in the market, imported and domestic ones are the main ones. Imported products are especially represented by Bayer’s Desmodur L75. This type of product is usually produced by thin film evaporation, and the product is separated in the later stage by using high-end imported equipment-thin film still, so that the free toluene diisocyanate (TDI) in the final product is very low. (Usually below 0.5), so as to achieve the effect of environmental protection and low ionization. However, the equipment investment of thin film evaporation method is large, the technical difficulty is high, the control process is complicated, and the maintenance cost is also high, which is not acceptable to ordinary enterprises. [0003] At present, the technical lev...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for preparing a low-free high-compatibility polyurethane curing agent for the problems existing in the existing curing agent preparation method. The product prepared by this method has low free, low viscosity, high solid content and high compatibility. and other properties, effectively solving the technical problems of environmental protection, low ionization, low viscosity, high solid content, and high compatibility that are difficult for many domestic manufacturers to solve

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