Thermosetting Powder Coating for Crack Resistance
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Solution Overview
Problem
Epoxy resin powder coating materials lack sufficient crack resistance during bending processing, especially in severe environments like cold regions, and exhibit sagging issues during application, compromising their workability and heat resistance.
Innovation Solution
A thermosetting powder coating material composition comprising a bisphenol type epoxy resin with an epoxy equivalent weight of 600-800 g/eq, a bisphenol type phenol resin curing agent, and a combination of an imidazole compound and an amine-epoxy adduct-type compound as curing agents, without a rubber-modified epoxy resin, to enhance plasticity, heat resistance, and crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional epoxy resin powder coating material is used, then heat resistance is sufficient, but crack resistance during bending processing is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the epoxy resin system by selecting specific epoxy resins with epoxy equivalent weights of 600-800 g/eq and controlling the curing agent ratio (D2/D1 between 1.0-3.7), which optimizes the crosslinking structure to achieve both flexibility for crack resistance and thermal stability for heat resistance
Solution Approach 2:
The patent creates a composite curing system by combining two types of curing agents (D1 and D2) with different chemical characteristics, where D1 provides baseline curing and D2 enhances plasticity and crack resistance, resulting in a synergistic effect that maintains both heat resistance and bending flexibility
2Ease of operation
If the coating material is applied in powder state and heated to melt, then coating is achieved, but sagging occurs reducing workability
Solution Approach 1:
The patent optimizes the molecular weight and epoxy equivalent weight parameters of the base resin to control the melting behavior and viscosity characteristics, ensuring the coating material maintains appropriate flow properties during application and curing without excessive sagging
3Strength
If the coating film is formed on bus bar, then insulation is provided, but plasticity for bending is insufficient
Solution Approach 1:
The patent adjusts the epoxy equivalent weight parameter to a specific range (600-800 g/eq) that balances the crosslinking density and molecular chain flexibility, providing sufficient plasticity for bending applications while maintaining the protective and insulating properties required for bus bar applications
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 coating material achieves high plasticity and heat resistance, preventing cracks at low temperatures and during thermal aging, while maintaining workability and preventing sagging, thus ensuring effective bending processing and long-term thermal stability.
Implementation Method 1
a compound (D) for activating (C), wherein (D1) and (D2) are included as (D)... (D1) an imidazole compound... (D2) an amine-epoxy adduct-type compound
Implementation Method 2
it is applied in a powder (solid) state to a surface of an object to be coated and, then, heated to melt (liquidate) the powder and, furthermore, heated to form a film (solidate)
Data Source
AI summary
There is provided a thermosetting powder coating material capable of forming a cured product having excellent workability at coating and high plasticity as well as heat resistance, resulting in heat resistance and crack resistance at bending processing. (A) denotes a bisphenol type epoxy resin having epoxy equivalent weight of 600 to 800 g/eq (not including 800 g/eq), (B) a rubber-modified epoxy resin, (C) a bisphenol type phenyl resin curing agent (D) a compound for activating (C), (D1) an imidazole compound and (D2) an amine-epoxy adduct type compound. The thermosetting powder coating material is composed of a finely pulverized composition. The composition comprises (A), (C) and (D) but does not comprise (B). (D) comprises (D1) and (D2), and a weight ratio of (D2) with respect to (D1) is 1.0 or more and 3.7 or less when (D1) is 1.