A secondary aqueous dispersion of hydroxyl-containing polyacrylate and its preparation method

Abstract

The invention relates to a waterborne hydroxyl-containing acrylic resin secondary dispersion and a preparation method thereof. The dispersion is prepared from the following components in parts by mass: 1-3 parts of co-solvent, 0.5-2 parts of carboxyl-containing monomer, 5-15 parts of hydroxyl-containing monomer, 15-35 parts of acrylate monomer, 5-15 parts of vinyl monomer, 0.5-1 part of initiator,0.5-2 part of neutralizing agent, and 48-55 parts of deionized water. The waterborne hydroxyl-containing acrylic resin secondary dispersion prepared by the preparation method of the invention adoptsa two-step polymerization process to arrange carboxyl in a copolymer to be at the end of the molecular chain of the copolymer, so that in a phase inversion process, the polymer can be more hydrophilically dispersed, and the waterborne hydroxyl-containing acrylic resin secondary dispersion can be prepared under an extremely low acid value.

Description

technical field [0001] The invention belongs to the technical field of coatings, in particular to a secondary dispersion of aqueous hydroxyl-containing acrylic resin and a preparation method thereof. Background technique [0002] Traditional solvent-based polyurethane coatings have been widely used in various fields due to their advantages such as strong adhesion, adjustable elasticity, high and low temperature resistance, solvent resistance, wear resistance, high gloss, and full coating film, but they contain toluene, Organic solvents such as xylene that are harmful to the environment and humans. Water-based polyurethane coatings have the advantages of non-toxic, non-flammable, non-polluting, energy-saving, etc., and are gradually replacing traditional solvent-based coatings, which is in line with the development direction of coatings. [0003] Water-based acrylic resin has the characteristics of excellent film-forming properties, good weather resistance, excellent color a...

AI Technical Summary

Problems solved by technology

[0005] In order to pursue dispersion and storage stability, most of the acrylate secondary dispersions (anionic type) introduce more carboxyl groups during synthesis, thereby increasing the acid value of the resin, resulting in the water resistance and alkali resistance of the hydroxy acrylic resin. The property decreases, and the increase of the acid value makes the viscosity of the dispersion larger, and the solid content cannot be increased

In the case of high acid value, the prepared polyurethane coating has poor water resistance and is only suitable for the preparation of amino baking paint

In order to reduce the viscosity of the system in Chinese patents CN101914185A and CN102850703A, more solvents were added during the reaction process, but they were not removed later, resulting in higher VOC content in the product

Chinese patent CN104356291A provides a kind of preparation method of water-based hydroxyacrylic resin with simple process, but its polymerization temperature is too low, and the amount of reactive diluent introduced is very little (less than 4%). In the case of a small amount of solvent added, it is very unlikely to be realized in actual production operations, and the storage stability of the resin is very poor due to the high viscosity of the resin and the inhomogeneity of neutralization and emulsification

In addition, at a lower reaction temperature, the reactivity of glycidyl tert-carbonate with carboxyl groups is low, and the residual glycidyl tert-carbonate will adversely affect the performance of resins and coatings

Chinese patents CN201610446235.2, CN201710503885.0 and CN201710562230.0 participate in the reaction by introducing reactive diluents to reduce the viscosity of the system, thereby increasing the solid content, but they cannot overcome the transformation of the dispersion from water-in-oil W / O type to The problem of sharp increase in viscosity in the oil-in-water O / W process, due to the low acid value of the resin, it is difficult to emulsify without high-speed dispersion when adding water, and even need to add a reactive emulsifier, which increases the production cost

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