Caprolactone-Modified Hyperbranched Polyester Coating for Scratch Resistance
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Solution Overview
Problem
High glossy coatings for automobiles, particularly black colors, suffer from increased fine scratches over time, leading to reduced gloss, transparency, and increased haze, with existing urethane clear paints offering poor scratch resistance and compromising impact and flexibility when silica is used.
Innovation Solution
A coating composition comprising caprolactone-modified hyperbranched polyester polyol, first and second acrylic resins, and a solvent, along with additives like wetting agents and light stabilizers, which forms a scratch-resistant and high-strength coating layer when applied with a curing agent, enhancing elasticity, impact resistance, and self-restoration properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If urethane clear paint is used for high glossy coating, then the coating has excellent strength, but it has poor scratch resistance due to high glass transition temperature of resins
Solution Approach 1:
The patent changes the glass transition temperature parameter of the resin from high (conventional urethane) to low (below -50°C) to fundamentally alter the coating's mechanical properties, enabling both high strength and excellent scratch resistance by allowing molecular chains to move and self-repair scratches at room temperature
2Object-affected harmful factors
If silica is added to increase coating strength and prevent scratches, then scratch resistance improves, but impact resistance and flexibility are lowered
Solution Approach 1:
The patent extracts and eliminates silica and other inorganic fillers from the coating formulation, relying instead on a specially designed low glass transition temperature polymer resin system that provides scratch resistance through molecular chain mobility rather than through inorganic reinforcement, thereby maintaining flexibility and impact resistance
Solution Approach 2:
The patent changes the fundamental approach from inorganic reinforcement to organic polymer design by adjusting the glass transition temperature parameter to below -50°C, creating a flexible yet scratch-resistant coating system without compromising impact resistance
3Illumination intensity
If high glossy coating is applied to automobile exterior, then appearance quality improves, but fine scratches increase over time causing gloss reduction and haze increase
Solution Approach 1:
The patent creates a self-healing coating system where the low glass transition temperature resin automatically repairs fine scratches through molecular chain movement and reorganization at room temperature, eliminating the need for external intervention and maintaining gloss and transparency over time
Solution Approach 2:
The patent changes the glass transition temperature parameter to below -50°C, transforming the coating from a static, scratch-prone surface to a dynamic, self-repairing surface that maintains its optical properties by continuously adapting at the molecular level
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 composition effectively restores scratches, provides excellent water, acid, and heat resistance, while maintaining high gloss and strength, improving the durability and appearance of automobile exterior coatings.
Implementation Method 1
an isocyanate curing agent, wherein the caprolactone-modified hyperbranched polyester polyol has an acid value of 10 mg/KOH or less, a hydroxyl group content of 6% to 8%, and a weight average molecular weight of 1,000 to 2,000
Data Source
AI summary
A coating composition may include 5 wt % to 20 wt % of a caprolactone-modified hyperbranched polyester polyol, the caprolactone-modified hyperbranched polyester polyol obtained from polyhydric alcohol including caprolactone triol, 30 wt % to 50 wt % of a first acrylic resin, the first acrylic resin having a hydroxyl group, 15 wt % to 25 wt % of a second acrylic resin, the second acrylic resin having a hydroxyl group and having a glass transition temperature higher than that of the first acrylic resin, and an extra solvent.