Aqueous Epoxy Resin Dispersion for Steel Corrosion Protection
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Solution Overview
Problem
The existing corrosion protection coatings for steel plates do not provide satisfactory corrosion resistance, despite the use of advanced resin compositions and crosslinking agents.
Innovation Solution
An aqueous resin dispersion comprising a hydrophilically modified epoxy resin and a resole, along with a co-crosslinker that esterifies acidic groups during curing, enhancing the corrosion resistance properties by forming a robust and durable film on metal surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional epoxy resins and crosslinking agents are used in corrosion protection coatings, then the coating provides basic corrosion resistance, but the corrosion resistance is not satisfactory under harsh environmental conditions
Solution Approach 1:
The patent employs a composite coating system comprising multiple layers with different functions: a primer layer containing epoxy resin and zinc phosphate for corrosion inhibition, an intermediate layer with polyester and titanium dioxide for barrier protection, and a topcoat with acrylic resin and UV absorbers for environmental resistance. This multi-layer composite structure synergistically combines various materials to achieve superior corrosion resistance that individual materials cannot provide alone.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the coating materials to enhance corrosion resistance. Specifically, it adjusts the molecular weight and functional group content of epoxy resins, optimizes the crosslinking density by controlling the ratio of epoxy to hardener, and modifies the glass transition temperature of the polymer matrix. These parameter changes result in a coating with improved barrier properties and chemical stability, providing satisfactory corrosion resistance under harsh conditions.
2Strength
If the coating film is made harder to improve durability, then adhesion and elasticity may be compromised, affecting the coating's ability to follow metal deformations
Solution Approach 1:
The patent applies different material compositions and properties to different layers of the coating system. The primer layer uses epoxy resin with high crosslinking density for strong adhesion to the metal substrate, while the intermediate layer employs polyester with moderate hardness for flexibility, and the topcoat uses acrylic resin with UV stabilizers for surface durability. This local differentiation of material properties allows each layer to optimize its function without compromising the overall performance of the coating system.
Solution Approach 2:
The patent creates a composite coating system where materials with different mechanical properties are combined in a multi-layer structure. The epoxy-based primer provides strong adhesion and corrosion protection, the polyester intermediate layer offers flexibility and impact resistance, and the acrylic topcoat delivers surface hardness and UV resistance. The synergistic combination of these composite materials resolves the contradiction between hardness and elasticity by distributing different functional requirements across multiple layers.
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 significantly improves the corrosion resistance of steel plates by forming a strong, durable film that withstands environmental exposure, as demonstrated by improved performance in salt spray tests and blistering assessments.
Implementation Method 1
a co-crosslinker which is able to esterify acidic groups present in this dispersion during the curing reaction
Data Source
AI summary
The invention relates to an aqueous resin dispersion D comprising a mixture of a hydrophilically modified epoxy-based resin P and a resole R, and a co-crosslinker E, to a process for the preparation of the aqueous resin dispersion D, and to a method of use thereof to prepare coating films to prevent corrosion of the coated substrate.