Electrocoat binder with carboxylate and ester groups
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Solution Overview
Problem
The existing industrial coating processes for metal substrates in automotive manufacturing require a phosphating pretreatment step, which is costly and complex, and does not provide adequate corrosion protection without additional treatments.
Innovation Solution
An electrocoat coating composition with a binder containing a carboxylate group separated by 2 to 4 carbons from an ester group and a phosphorylated resin, which can be electrodeposited onto unphosphated metal substrates, providing enhanced corrosion protection by forming a coordinate bond with the metal substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphating pretreatment is applied to metal substrates, then corrosion protection and adhesion are improved, but process complexity and manufacturing costs increase
Solution Approach 1:
The patent combines the phosphating pretreatment function and the electrocoat adhesion function into a single electrocoat composition. The binder contains both phosphorous-containing groups (for corrosion protection through coordinate bonding with metal) and carboxylate/ester groups (for adhesion), eliminating the need for separate phosphating and coating steps while maintaining both protection and adhesion benefits
Solution Approach 2:
The electrocoat composition is designed to perform multiple functions simultaneously: corrosion protection through phosphorous groups, adhesion through carboxylate/ester groups, and film formation through the binder system. This multi-functional coating replaces the traditional multi-step process (cleaning, phosphating, rinsing, coating) with a single electrocoat application step
2Reliability
If phosphating pretreatment is applied to metal substrates, then corrosion protection is improved, but manufacturing costs increase
Solution Approach 1:
The patent combines the phosphating pretreatment function and the electrocoat adhesion function into a single electrocoat composition. The binder contains both phosphorous-containing groups (for corrosion protection through coordinate bonding with metal) and carboxylate/ester groups (for adhesion), eliminating the need for separate phosphating and coating steps while maintaining both protection and adhesion benefits
Solution Approach 2:
The patent extracts the essential function of phosphating pretreatment (corrosion protection through metal coordination) and incorporates it directly into the electrocoat binder system. By taking out the phosphating step from the process sequence and integrating its function into the coating composition, the patent eliminates equipment and operational costs associated with separate phosphating lines
3Reliability
If phosphate pretreatment steps are included in the coating process, then corrosion protection is enhanced, but processing time increases
Solution Approach 1:
The patent combines the phosphating pretreatment function and the electrocoat adhesion function into a single electrocoat composition. The binder contains both phosphorous-containing groups (for corrosion protection through coordinate bonding with metal) and carboxylate/ester groups (for adhesion), eliminating the need for separate phosphating and coating steps while maintaining both protection and adhesion benefits
Solution Approach 2:
The phosphorous-containing groups in the binder are pre-positioned to provide corrosion protection upon deposition, eliminating the need for preliminary phosphating treatment. The binder composition is designed beforehand to contain both corrosion protection mechanisms and adhesion mechanisms, ready to function simultaneously when applied
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
This approach eliminates the need for phosphating pretreatment, reducing costs and simplifying the coating process while achieving superior corrosion protection and adhesion, as the carboxylate/ester groups enhance the effectiveness of phosphorous-containing groups in the coating.
Implementation Method 1
This is especially advantageous when the coating is applied as an anticorrosive coating onto a substrate having an irregular surface, such as a motor vehicle body. The even, continuous coating layer over all portions of the metallic substrate provides maximum anticorrosion effectiveness.
Implementation Method 2
A carboxylate group in proximity to an ester group on the binder, which may be produced by reaction of a hydroxyl group on the binder with a cyclic anhydride, unexpectedly enhances the effectiveness of phosphate or phosphonic acid ester groups of the binder in corrosion protection of a metal substrate by its interaction with the metal substrate surface.
Data Source
AI summary
An aqueous electrodeposition coating composition comprising a cathodically electrodepositable binder, the binder comprising a phosphorylated resin and a carboxyl group separated by from 2 to 4 carbons from an ester group, provides corrosion protection equivalent to that obtained by the conventional phosphate pretreatment-electrodeposition coating process.