Polyurethane pigment dispersing agent and method for preparing same

Abstract

The invention provides a method for preparing a polyurethane pigment dispersing agent. The method includes A), carrying out reaction on diisocyanate and dihydric alcohol to obtain polyurethane prepolymers; B), carrying out reaction on the polyurethane prepolymers, anionic hydrophilic monomers and non-ionic hydrophilic monomers to obtain intermediates; C), neutralizing the intermediates and carrying out reaction on the intermediates, end capping agents or chain extenders to obtain the polyurethane pigment dispersing agent. The non-ionic hydrophilic monomers are selected from a type or a plurality of types of trimethylolpropane polyethylene glycol monoethylether and trimethylolpropane polyethylene glycol propylene glycol monomethyl ether; the anionic hydrophilic monomers are selected from a type or a plurality of types of methylol carboxylic acid, amino acid, sulfamic acid and sulfamate. The method has the advantages that amphiphilic macromolecular polymers with comb structures are the specific non-ionic hydrophilic monomers, accordingly, the steric hindrance stability of molecular spaces can be improved, and the viscosity of the prepolymers can be lowered; the charge stability can be improved by the specific anionic hydrophilic monomers, and accordingly the polyurethane pigment dispersing agent is good in dispersion stability.

Description

technical field [0001] The invention relates to the field of materials, in particular to a polyurethane pigment dispersant and a preparation method thereof. Background technique [0002] At present, there are two main types of water-based pigment dispersants, one is low-molecular surfactants; the other is high-molecular dispersants. Examples include styrene maleic anhydride polymers, polymers containing linear alkyl hydrophobic segments and carboxylic acid hydrophilic segments. The mechanism of dispersion stability is mainly to use various polar groups or non-polar groups to combine with the surface of pigments such as hydrophobic bonding, hydrogen bonding, and dispersion induction, and to use the steric hindrance and charge repulsion of dispersant molecules to play a role. Stabilization, through the external force of dispersion and grinding, the pigment forms a stable dispersion system in the water-based system. [0003] Low-molecular surfactants are used as dispersants. ...

AI Technical Summary

Problems solved by technology

Excessively large molecular weight dispersants will cause bridge flocculation during application, resulting in reduced paint gloss and hiding properties

[0005] In the prior art, in order to control the molecular weight, solvent polymerization is often used, which is polluting and unsafe

Polyurethane polymer dispersant is a new type of dispersant, but this kind of dispersant has problems in the stability of pigment dispersion fineness due to its small steric hindrance

At the same time, the existing polyurethane synthesis uses an organotin catalyst, which is poor in environmental protection; and in the conventional polyurethane synthesis process, due to the need to use a solvent to reduce the viscosity of the prepolymer, the environmental protection is poor; polyurethane dispersants mostly use non-ionic hydrophilic groups, Lack of charge stabilization, resulting in poor fineness stability of pigment dispersions, and poor dispersion stability for polar inorganic pigments