Preparation method of environmental protection curing agent with good adhesion and yellowing resistance

Abstract

The present invention relates to a preparation method for an environmentally-friendly anti-yellowing curing agent with a good adhesive force. The preparation method comprises the following steps of: step 1, adding TDI into a solvent for dissolving, and adding a low molecular weight alcohol containing 1-3 hydroxyl groups for a prepolymerization reaction, wherein the low molecular weight alcohol accounts for 20%-35% of the total amount of the alcohol; step 2, after the prepolymerization reaction, adding HDI and the remaining low molecular weight alcohol containing 1-3 hydroxyl groups, and simultaneously adding a silanol for the prepolymerization reaction, wherein the molar ratio of TDI : HDI = 0. 5-1:1, and the molar ratio of the salinol: HDI=0.05-0.2:1; and step 3, after the prepolymerization reaction, adding a trimerization catalyst, continuously detecting contents of NCO (NCO%) and free TDI (TDI%), and when the content of NCO (NCO%) reaches 8.5% and the content of a free monomer is less than 0.5%, adding a polymerization inhibitor to terminate the reaction, and cooling for material unloading. According to the method of the present invention, a trimerization method is used for reducing the content of the free monomer, the process flow is simple, no large investment in equipment is needed, the production cost is low, the product performance fully fulfills the application requirements in the paint field, and is conductive to environmental protection and health; and when the curing agent is used in coatings, the paint film has good adhesive force with the substrate, and the recoating adhesive force is more excellent, and anti-yellowing and anti-weathering performance of the paint film is better.

Description

Technical field [0001] The invention discloses a curing agent field in coatings and adhesives, in particular to a preparation method of an environmentally friendly curing agent with good adhesion and resistance to yellowing. Background technique [0002] At present, in wood coatings, many of the substrates of the boards have not been well treated, and the incomplete polishing has led to the delamination of the primer or topcoat, which seriously affects the broadness of the product and makes the furniture factory increase Labor cost; because the treatment of free monomers after reaction is generally used in the world to separate unreacted monomers through thin-film evaporator evaporation or solvent extraction processes, but this method has high investment in production equipment, complex processes, and long production cycles. Problems such as high production costs; silicone is an organic-inorganic hybrid material with excellent heat resistance, weather resistance, water resistance...

AI Technical Summary

Problems solved by technology

[0002] At present, in wood coatings, many of the substrates of the boards have not been well treated, and the sanding is not thorough, which leads to the delamination of the primer or topcoat, which seriously affects the wide use of the product and increases the furniture factory. Labor costs; because the treatment of free monomers after reaction is generally separated from unreacted monomers through thin film evaporator evaporation or solvent extraction in the world, but this method requires high investment in production equipment, complex processes, and long production cycles. Problems such as high production costs; silicone is an organic-inorganic hybrid material with excellent heat resistance, weather resistance, water resistance and low surface tension