Zirconium Pretreatment Coating Copper Chelation

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Solution Overview

Problem

Current zirconium-based pretreatment coating compositions for metal substrates face issues with copper deposition, leading to reduced performance in corrosion resistance and paint adhesion, and have limited pot life, resulting in increased scrap rates and manufacturing costs due to line stoppages and the need for environmentally harmful heavy metal-based coatings.

Innovation Solution

A zirconium-based pretreatment coating composition with a copper chelating agent, such as tartaric acid, is used to control copper deposition on metal substrates, maintaining corrosion resistance and enhancing paint adhesion while extending the pot life of the coating bath by maintaining a copper to zirconium atomic ratio of 1.1 or less, allowing for longer immersion times without performance degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If zirconium-based pretreatment coating composition is used to replace heavy metal-based coatings, then environmental harm is reduced, but copper deposition occurs leading to reduced corrosion resistance and paint adhesion

Engineering Contradiction:

Improveenvironmental harm from heavy metal wasteVSAvoidcorrosion resistance and paint adhesion

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The harmful element (copper) is selectively removed from the coating composition through chelating agents that bind copper ions, preventing their deposition on the metal substrate while maintaining the beneficial zirconium-based coating properties

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Chelating agents act as intermediary substances that selectively bind to copper ions in the coating bath, preventing copper deposition while allowing zirconium and other beneficial metals to form the protective coating on the substrate

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If zirconium-based pretreatment coating composition is used, then environmentally friendly coating is achieved, but pot life is limited leading to increased scrap rates

Engineering Contradiction:

Improveenvironmental harm from heavy metal wasteVSAvoidpot life and scrap rate

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The coating composition includes copper chelating agents that continuously monitor and control copper ion levels in the bath, maintaining optimal coating performance throughout extended pot life and preventing degradation that would lead to scrap

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The composition parameters are optimized by controlling the ratio of copper chelating agent to zirconium content, ensuring stable coating performance over extended periods and maximizing pot life while maintaining quality standards

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If copper is present in zirconium-based coating composition, then coating formation is facilitated, but copper to zirconium atomic ratio exceeds 1.1 reducing paint adhesion

Engineering Contradiction:

Improvecoating formationVSAvoidpaint adhesion

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The copper to zirconium atomic ratio is precisely controlled to remain at or below 1.1 through the use of copper chelating agents, optimizing both coating formation characteristics and subsequent paint adhesion performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Copper chelating agents serve as intermediaries that regulate copper ion availability during coating formation, enabling controlled copper incorporation that facilitates coating formation while preventing excessive copper deposition that would harm paint adhesion

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively improves paint adhesion and maintains corrosion resistance, reducing scrap rates and manufacturing costs by extending the pot life of the coating bath and allowing for broader substrate compatibility without the need for heavy metal-based coatings.

Implementation Method 1

a copper chelating agent, such as tartaric acid, is used to control copper deposition on metal substrates

Methodology Applied

Scientific EffectChelation:

Implementation Method 2

a zirconium-based conversion coating deposited on a metal substrate by contact with a working bath containing dissolved zirconium

Methodology Applied

Scientific EffectConversion coating:

Data Source

PatentUS10094026B2Metal pretreatment composition containing zirconium, copper, and metal chelating agents and related coatings on metal substrates

Publication Date: 2018.10.09 HENKEL KGAA

AI summary

Disclosed is a zirconium-based metal pretreatment coating composition that includes a metal chelator that chelates copper in the metal pretreatment coating composition and thereby improves adhesion of paints to a metal substrate coated with the pretreatment coating composition and the chelating agent is present in a sufficient amount to ensure that in the deposited pretreatment coating on the metal substrate the average total atomic % of copper to atomic % of zirconium is equal to or less than 1.1. The pretreatment coating composition is useful for treating a variety of metal substrates.