Silicon-Based Non-Cr Passivating Composition for Metal Surfaces
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Solution Overview
Problem
Current non-Cr passivating compositions face limitations in achieving high surface energy, corrosion resistance, solvent resistance, boiling water resistance, heat resistance, and darkening resistance, while also suffering from issues like shrinkage, irritating odors, and limited shelf life due to low compatibility and high costs of surfactants and hydrophilic blocked polyisocyanates.
Innovation Solution
An aqueous non-Cr passivating composition comprising a silicon-containing compound and a water-borne polymer, specifically a combination of polyurethane resin and polyacrylate resin, which forms a passivation layer with enhanced surface energy and improved resistance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If polyether-modified polyacrylates are added to increase surface energy, then surface energy increases, but shrinkage occurs and irritating odors are released
Solution Approach 1:
The patent changes the chemical composition parameters by using silicon-containing compounds (such as silanes) instead of polyether-modified polyacrylates. The silicon-containing compound undergoes hydrolysis and condensation reactions to form a passivation layer with high surface energy (40-50 dyne/cm) without causing shrinkage or releasing irritating odors, thus resolving the contradiction between improving surface energy and avoiding harmful effects.
2Illumination intensity
If hydrophilic blocked polyisocyanates are used to increase surface energy, then surface energy increases, but resistance against boiling water deteriorates and cost increases
Solution Approach 1:
The patent replaces hydrophilic blocked polyisocyanates with silicon-containing compounds. The silicon-containing compound forms a inorganic-organic hybrid passivation layer that simultaneously achieves high surface energy (40-50 dyne/cm) and excellent resistance against boiling water, heat, and corrosion, eliminating the trade-off between surface energy and boiling water resistance.
3Illumination intensity
If acidic systems with pH 3-5 are used to achieve high surface energy, then surface energy increases, but adhesion to articles pretreated with high pH degreasing agents decreases
Solution Approach 1:
The patent adjusts the pH parameter of the passivation composition to be neutral or slightly basic (pH 7-9), matching the high pH degreasing agents used in pretreatment. The silicon-containing compound forms a passivation layer with high surface energy (40-50 dyne/cm) that maintains excellent adhesion to articles pretreated with high pH degreasing agents, resolving the contradiction between surface energy and adhesion.
4Illumination intensity
If surfactants are added to increase surface energy, then surface energy increases, but shelf life of the composition shortens
Solution Approach 1:
The patent replaces organic surfactants with silicon-containing compounds that form an inorganic-organic hybrid passivation layer. The silicon-containing compound maintains composition stability during storage and achieves high surface energy (40-50 dyne/cm) after passivation, significantly extending the shelf life of the composition while maintaining the desired surface energy.
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 provides excellent storage stability and resistance against corrosion, solvent, boiling water, heat, and darkening, while maintaining good repaintability and adhesion, thus overcoming the limitations of existing technologies.
Implementation Method 1
The silicon-containing compound undergoes hydrolysis and condensation reactions to form a passivation layer
Implementation Method 2
The silicon-containing compound undergoes hydrolysis and condensation reactions to form a passivation layer
Implementation Method 3
The excellent adhesion between the passivation layer and the protection layer is of great importance
Data Source
AI summary
Disclosed herein is an aqueous non-Cr passivating composition including, on the basis of the weight of the non-Cr passivating composition: (a) 5 to 20% by weight of a silicon-containing compound; and (b) 5 to 15% by weight of a water-borne polymer, which is selected from the group consisting of a polyurethane resin, an epoxy resin, a polyacrylate resin and the combination thereof. Further disclosed herein are a metal with a surface passivated by the aqueous non-Cr passivating composition and an article having a metallic surface passivated by the aqueous non-Cr passivating composition, and a process for passivating a metallic surface with the aqueous non-Cr passivating composition.