Zirconium Pretreatment Agent for Thick Coating Adhesion
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Solution Overview
Problem
Existing chemical conversion treatment agents for metal substrates before paint application do not adequately provide coating films with excellent adhesion, salt water resistance, and impact resistance, particularly for thick films exceeding 30 μm, and there is a lack of investigation into the optimal ratios of amino group-containing silane coupling agents and polyallylamine in these treatments.
Innovation Solution
A pretreatment agent containing zirconium, fluorine, and a predetermined ratio of amino group-containing silane coupling agents and polyallylamine, along with optional metal elements like aluminum, zinc, or magnesium, is used to enhance the adhesion and resistance properties of the coating film, with specific mass content ranges for each component to ensure optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a chemical conversion treatment agent containing zirconium, titanium or hafnium is used instead of chromate or zinc phosphate agents, then environmental compatibility is improved, but adhesion and corrosion resistance of the coating film may deteriorate
Solution Approach 1:
The patent uses a composite chemical conversion treatment agent containing multiple metal elements (zirconium, titanium, or hafnium) combined with fluorine and silicon. This composite formulation achieves both environmental compatibility by replacing chromium and phosphate, and maintains reliable adhesion and corrosion resistance through the synergistic effects of the multiple components forming a complex conversion film on the metal substrate
Solution Approach 2:
The patent specifies precise compositional parameters for the conversion agent, including the presence of zirconium/titanium/hafnium at specific concentrations, fluorine content, and silicon-containing compounds. By controlling these chemical parameters and ratios, the treatment achieves optimal balance between environmental safety and coating performance
2Reliability
If the coating film thickness is increased to more than 30 μm to improve protection, then adhesion and corrosive substance-blocking capability are improved, but coating film stripping occurs due to stress
Solution Approach 1:
The patent applies a chemical conversion treatment as a preliminary step before paint coating. This conversion treatment creates a preparatory layer on the metal substrate that pre-establishes strong chemical bonds and reduces internal stress, enabling the subsequent thick coating film (>30 μm) to maintain adhesion and resist stripping while providing enhanced protection
Solution Approach 2:
The chemical conversion film acts as an intermediary layer between the metal substrate and the thick paint coating. This intermediate layer, formed by zirconium/titanium/hafnium fluoride compounds, serves as a stress-absorbing buffer that prevents direct stress transmission from the thick coating to the substrate, thereby preventing film stripping while maintaining protection capability
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 proposed pretreatment agent achieves excellent adhesion, salt water resistance, and impact resistance for coating films, even at thicknesses of 30 μm or more, by imparting flexibility and enhancing the chemical conversion film's properties, thereby preventing coating film stripping and improving overall film quality.
Implementation Method 1
the surface of the metal substrate is, before forming a coat, chemically treated to forma chemical conversion film
Implementation Method 2
a chemical conversion treatment agent that comprises at least one selected from a group consisting of zirconium, titanium and hafnium, fluorine, and an amino group-containing silane coupling agent
Data Source
AI summary
The pretreatment agent for use before forming a coat by paint application of the present invention contains (A) one or more metal elements selected from a group consisting of zirconium, titanium and hafnium, (B) fluorine, (C) one or more coupling agents selected from an amino group-containing silane coupling agent, its hydrolyzate, and its polymer, and (D) a component of at least one of an allylamine and a polyallylamine, in which the ratio by mass of the coupling agent (C) to the component (D), (C/D) is 1 or more. The coating method by paint application of the present invention includes a chemical conversion treatment step of chemically treating a metal substrate with the pretreatment agent, and a step of forming a coat by paint application on the chemically-treated metal substrate. When a coating film is formed through forming a coat by paint application on the surface of a metal substrate that has been pretreated according to the present invention, the coating film can have excellent adhesion, salt water resistance and impact resistance.