Cationic Electrodeposition Coating for Adhesion and Rust Prevention

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Solution Overview

Problem

Existing cationic electrodeposition coating compositions lack sufficient adhesion and hydrophobicity, which are crucial for effective rust prevention.

Innovation Solution

A cationic electrodeposition coating composition comprising an aminated epoxy resin with a molecular weight distribution of 2.7 or less and a rate of elongation of 0.1 to 4.5%, combined with a blocked polyisocyanate curing agent, to enhance adhesion and hydrophobicity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional aminated epoxy resin is used in cationic electrodeposition coating, then the coating can be formed, but the adhesion and hydrophobicity are insufficient

Engineering Contradiction:
ImproveadhesionVSAvoidmolecular weight distribution control
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by strictly controlling the molecular weight distribution (Mw/Mn ≤ 2.7) of the aminated epoxy resin and the rate of elongation (0.1-4.5%) of the coating film. These precise parameter specifications transform the conventional approach into a controlled process that achieves both good adhesion and hydrophobicity simultaneously, resolving the technical contradiction between improving coating performance and maintaining manufacturing feasibility.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional aminated epoxy resin is used in cationic electrodeposition coating, then the coating can be formed, but the hydrophobicity (blocking property) is insufficient

Engineering Contradiction:
ImprovehydrophobicityVSAvoidmolecular weight distribution control
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent resolves this contradiction by implementing precise parameter control: molecular weight distribution (Mw/Mn ≤ 2.7) and rate of elongation (0.1-4.5%). These parameter specifications ensure that the coating film achieves adequate hydrophobicity and blocking property while remaining manufacturable through controlled synthesis processes of the aminated epoxy resin.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the molecular weight distribution of aminated epoxy resin is reduced to 2.7 or less, then adhesion and corrosion resistance improve, but the synthesis process becomes more complex

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidsynthesis process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent addresses this contradiction by establishing clear parameter thresholds (Mw/Mn ≤ 2.7, rate of elongation 0.1-4.5%) that guide the synthesis process. By converting the complex quality requirement into specific measurable parameters, the patent simplifies process control and monitoring while ensuring the aminated epoxy resin achieves the desired molecular uniformity for optimal corrosion resistance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex qualitative assessment of synthesis quality with quantitative parameter measurement and control. Instead of relying on complex mechanistic understanding of side reactions, the invention uses measurable parameters (molecular weight distribution ratio and rate of elongation) to objectively control and verify the synthesis outcome, simplifying the overall process complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The composition achieves improved adhesion and hydrophobicity, resulting in enhanced corrosion resistance and rust prevention properties.

Implementation Method 1

the aminated epoxy resin is an aminated epoxy resin obtained by reacting an amine compound with an epoxy resin

Methodology Applied
Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

applying the cationic electrodeposition coating composition to a steel sheet

Methodology Applied
Scientific EffectElectrostatic Deposition: Electrostatic Deposition

Data Source

PatentUS12540249B2Cationic electrodeposition coating composition
Publication Date: 2026.02.03 NIPPON PAINT AUTOMOTIVE COATINGS

AI summary

The present invention provides a cationic electrodeposition coating composition with a rust prevention property enhanced by improving the adhesion and the blocking property of a coating film obtained from a cationic electrodeposition coating composition as compared with conventional ones. The present invention provides a cationic electrodeposition coating composition including an aminated epoxy resin and a blocked polyisocyanate curing agent, wherein the aminated epoxy resin is an aminated epoxy resin obtained by reacting an amine compound with an epoxy resin, the aminated epoxy resin has a molecular weight distribution of 2.7 or less, and a rate of elongation of an electrodeposition coating film formed by applying the cationic electrodeposition coating composition to a steel sheet such that a cured film thickness is 20 μm, followed by baking at 160° C. for 15 minutes, is 0.1 to 4.5%.