Chromium Surface Lacquer Adhesion via Cathodic Phosphonate Treatment
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Solution Overview
Problem
The adhesion between a chromium surface, particularly an electroplated chromium surface, and a lacquer is insufficient, leading to delamination and blistering, and existing methods fail to improve adhesion while maintaining the optical properties of the chromium surface.
Innovation Solution
A wet-chemical method involving an aqueous solution with phosphorous compounds and passing an electrical current through the chromium surface, using phosphorous compounds like 1—P(O)(OR2)(OR3) and R1—O—P(O)(OR2)(OR3), where R1 is a C1 to C12 alkyl group, and R2 and R3 are selected from specific residues, to enhance adhesion without altering the chromium surface's appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an adhesion promoting agent is applied to a chromium surface, then the adhesion between chromium surface and lacquer is improved, but the optical appearance of the chromium surface is compromised
Solution Approach 1:
The patent applies cathodic polarization (changing the electrical potential parameter) during the treatment to control the surface chemistry and morphology. This allows the chromium surface to be modified in a way that promotes adhesion while preserving the shiny optical appearance, resolving the contradiction between improving adhesion and maintaining optical properties
Solution Approach 2:
The patent uses an aqueous solution containing specific compounds (such as phosphonic acid esters or carboxylic acids) as intermediaries that facilitate adhesion promotion. These compounds act as mediators between the chromium surface and the lacquer, enabling strong bonding without requiring direct contact or modification that would compromise the optical appearance
2Reliability
If conventional adhesion promoting agents are used on chromium surfaces, then adhesion is improved, but delamination and blistering occur
Solution Approach 1:
The patent replaces mechanical adhesion promotion methods (such as surface abrasion or chemical etching that create micro-roughness) with an electrochemical approach using cathodic polarization. This substitution allows adhesion promotion through controlled surface chemistry modification rather than mechanical disruption, preventing delamination and blistering while maintaining coating integrity
Solution Approach 2:
By controlling the electrical potential parameter during the treatment process, the patent achieves uniform surface modification that promotes adhesion without creating the micro-roughness or chemical changes that lead to delamination and blistering. The parameter control ensures stable coating integrity
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 method significantly improves the adhesion between the chromium surface and the lacquer, as demonstrated by water resistance and cross-cut tests, while maintaining the shiny and decorative appearance of the chromium surface.
Implementation Method 1
contacting said substrate with an aqueous solution comprising at least one phosphorous compound according to formulae 1 and/or 2... while passing an electrical current through said substrate, at least one anode and the aqueous solution wherein said substrate serves as the cathode
Data Source
AI summary
The present invention concerns a method for increasing the adhesion between a chromium surface and a lacquer wherein said chromium surface is contacted with an aqueous solution comprising at least one phosphorous compound according to formulae R1—P(O)(OR2)(OR3) 1 and R1—O—P(O)(OR2)(OR3) 2 wherein R1 is a C1 to C12 alkyl group, linear, branched or cyclic comprising at least one polar residue and R2 and R3 are independently selected from the group consisting of hydrogen, lithium, sodium, potassium, ammonium and C1 to C4 alkyl while passing an external electrical current through said substrate and at least one anode wherein said substrate serves as the cathode.