Preparation and application method of a cathodic electrophoretic coating additive with good edge coating effect

Abstract

The invention relates to a method for preparing and using a cathodic electrophoretic coating additive with good edge coating effect. First, the amino-epoxy resin is obtained by performing a ring-opening reaction with a resin having a plurality of epoxy groups and an organic amine compound ; followed by adding monofunctional epoxy, reacting with the hydroxyl groups on the epoxy resin to graft, forming a modified epoxy resin with a branched structure; finally dispersing in acidic pure water to form a cationic microgel water dispersion body. The water dispersion is added into the prefabricated epoxy emulsion to obtain an electrophoretic emulsion, and mixed with electrophoretic black paste and pure water in a reasonable proportion to obtain a cathodic electrophoretic coating. Use this electrophoretic coating to apply electrophoretic coating on phosphating cold-rolled steel sheets. After heat curing, the thickness of the paint film is 18-20 microns, and the neutral salt spray can reach more than 1000 hours. Fog test 168H, the number of rust points is less than 15.

Description

technical field [0001] The invention relates to the field of cathodic electrophoretic paint, in particular to a method for preparing and using a cathodic electrophoretic paint additive with good edge coating effect. Background technique [0002] During the stamping process of auto parts, there will be edges and sharp corners. When the auto parts are undergoing cathodic electrophoretic deposition, these sharp edges are due to the existence of tip discharge phenomenon, and the solid components of the coating are concentrated on the sharp edges. Electrophoresis The original corner coverage is good when painting. However, during baking, due to the effect of the surface tension of the paint on the sharp edge, the thickness of the paint becomes thinner. At the same time, because of the heat flow of the paint film at a certain temperature, it is easy to shrink the edge, which eventually leads to the corrosion resistance of the product edge. Weak, sharp edges are prone to corrosion...

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Problems solved by technology

The molecular chain obtained by this method is linear, although the smoothness of the coating film is improved, but the effect of improving the corrosion resistance of the edge is not good

[0004] In addition, the patent notification number CN110437665A discloses a cathodic electrophoretic coating anticorrosion additive and a preparation method thereof, which is composed of a sharp-edged shrinkage-inhibiting additive and an anti-corrosion functional group additive, wherein the sharp-edge shrinkage-inhibiting additive is The anti-corrosion functional group additive is 5% to 15% of the cathodic electrophoretic paint emulsion in weight percentage, and this method requires more auxiliary agents The amount of addition, and the combination of various additives, are prone to defects such as poor compatibility and poor paint stability.

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