Acrylic-Silane Coating Composition for Multilayer Antifouling Adhesion
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Solution Overview
Problem
Conventional silicone-based antifouling coating materials require a two-pack curable type epoxy-based coating material as an undercoat, necessitating quick application and leading to issues with adhesion when applied on old antifouling coating films due to the high hardness of the epoxy-based coating, which can break the lower layer with lower hardness.
Innovation Solution
A coating composition containing a specific amount of acrylic resin with defined acid and hydroxyl values, combined with an epoxy group-containing silane coupling agent, forms a coating film with good adhesion to both epoxy-based undercoat and silicone-based antifouling coating materials, addressing the adhesion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a two-pack curable type epoxy-based coating material is used as an undercoat layer, then adhesion to the substrate is improved, but the high coating film hardness causes the lower layer to break when a self-polishing antifouling coating film is applied
Solution Approach 1:
The patent introduces a specific undercoat composition containing acrylic resin (A) with controlled acid value (10-35 mgKOH/g) and hydroxyl value (10-200 mgKOH/g), along with epoxy group-containing silane coupling agent (B) at 6-25% by mass in solid content, as an intermediary layer between the substrate and the self-polishing antifouling coating film. This intermediary undercoat provides both substrate adhesion and compatibility with the upper antifouling layer, preventing breakage while maintaining bonding strength.
Solution Approach 2:
The patent modifies the chemical parameters of the undercoat by precisely controlling the acid value and hydroxyl value of the acrylic resin, and the content of epoxy group-containing silane coupling agent. These parameter changes create an undercoat with optimized chemical composition that ensures compatibility with both the substrate and the upper antifouling coating layer, resolving the contradiction between adhesion strength and layer integrity.
2Strength
If a two-pack curable type epoxy-based coating material is used as an undercoat layer, then adhesion to the substrate is improved, but work restrictions increase due to the requirement to apply the silicone-based antifouling coating material quickly
Solution Approach 1:
The specially formulated undercoat acts as a stable intermediary layer that does not require immediate overcoating. Its controlled chemical composition (acrylic resin with specific acid and hydroxyl values, plus epoxy silane coupling agent) provides sufficient open time and working window, allowing application of the silicone-based antifouling coating material without urgent time constraints while maintaining strong substrate adhesion.
3Strength
If a two-pack curable type epoxy-based coating material is used as an undercoat layer on an old antifouling coating film, then adhesion to the old film is attempted, but the high hardness of the epoxy-based coating causes the old antifouling coating film to break
Solution Approach 1:
When applying over an old self-polishing antifouling coating film, the patent adjusts the undercoat composition parameters by controlling the acid value (10-35 mgKOH/g) and hydroxyl value (10-200 mgKOH/g) of the acrylic resin, and epoxy silane coupling agent content (6-25% by mass). This creates chemical compatibility with the softer old coating layer, ensuring adhesion without causing breakage, while still providing adequate bonding to the substrate beneath.
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 achieves strong adhesion between the undercoat and upper layers, ensuring durability and effectiveness of the antifouling coating film.
Implementation Method 1
a coating composition containing an acrylic resin (A) having a specific acid value and hydroxyl value, and further containing a specific amount of an epoxy group-containing silane coupling agent (B)
Data Source
AI summary
Provided is a coating composition that forms a coating film having good adhesion to both an epoxy-based undercoat coating film and an old antifouling coating film that is a lower layer, and having good adhesion to an antifouling coating film formed from a silicone-based antifouling coating material that is an upper layer. A coating composition containing an acrylic resin (A) having an acid value and an epoxy group-containing silane coupling agent (B), in which the acid value of the acrylic resin (A) is 10 mgKOH/g or more and 35 mgKOH/g or less and a hydroxyl value of the acrylic resin (A) is 10 mgKOH/g or more and 200 mgKOH/g or less, a content of the acrylic resin (A) in solid content of the coating composition is 25% by mass or more and 50% by mass or less, and a content of the epoxy group-containing silane coupling agent (B) in the solid content of the coating composition is 6% by mass or more and 25% by mass or less.