Acrylic Resin Coating with Side Chain Hydroxyls for Scratch Resistance
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Solution Overview
Problem
Conventional coating films, such as acryl-isocyanate-based and polysiloxane-based films, lack sufficient scratch resistance, leading to surface damage when exposed to strong external forces like sand during car washing and running, and struggle to balance hardness and adhesion.
Innovation Solution
A coating composition comprising acrylic resin with both short and long side chain hydroxyl groups and a polyisocyanate prepolymer, with optional polylactonepolyol, is used to create a multilayered coating film that enhances scratch resistance by combining adequate hardness and elasticity, allowing the film to flex and restore its original surface state under impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crosslinking density is increased to enhance hardness and scratch resistance, then scratch resistance is improved, but adhesion decreases and cracks are induced due to increased strain during curing
Solution Approach 1:
The invention changes the chemical composition parameters by introducing specific side chain hydroxyl groups (a1 and a2) into the acrylic resin structure and controlling their ratios, along with adjusting the isocyanate group to hydroxyl group ratio, to achieve optimal crosslinking density that balances hardness and adhesion
Solution Approach 2:
The invention creates a composite molecular structure within the acrylic resin by combining different hydroxyl group types (short side chain a1 and long side chain a2) in specific ratios, resulting in a material that exhibits both high hardness and good adhesion properties
2Strength
If the hardness of the coating film is increased to improve scratch resistance, then scratch resistance is improved, but the coating film becomes brittle and cannot withstand strong external forces without internal damage
Solution Approach 1:
The invention modifies the molecular structure parameters by introducing side chain hydroxyl groups with specific chain lengths and controlling their ratios, which adjusts the flexibility and impact resistance of the coating film while maintaining adequate hardness
Solution Approach 2:
The invention creates local flexibility within the coating film structure through the introduction of long side chain hydroxyl groups (a2) that can provide elastic deformation capacity, while the overall film maintains hardness through the crosslinking network formed by isocyanate groups
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 achieves extremely high scratch resistance, preventing surface damage from strong external forces and maintaining durability, even when rubbed by a cloud of sand, while maintaining weather resistance and adhesion.
Implementation Method 1
a coating composition comprising acrylic resin (A) having a short side chain hydroxyl group (a1) and a long side chain hydroxyl group (a2) and polyisocyanate prepolymer (C)
Data Source
AI summary
An object of the present invention is to provide a coating composition for forming a coating film having extremely high scratch resistance which could not be achieved up to now, concretely, such a degree of scratch resistance that even if the surface of a coating film is rubbed under strong external force by a cloud of sand flying and others while car washing and running, the surface can endure it. As a means of achieving this object, the coating composition according to the present invention comprises acrylic resin (A) having a short side chain hydroxyl group (a1) and a long side chain hydroxyl group (a2) and polyisocyanate prepolymer (C) as essential components and, as the need arises, further comprises polylactonepolyol (B), wherein the content ratio of the short side chain hydroxyl group (a1) to the long side chain hydroxyl group (a2), the total hydroxyl value of the short side chain hydroxyl group (a1) and the long side chain hydroxyl group (a2), the solid content ratio of the acrylic resin (A) to the polylactonepolyol (B), and the amount of the polyisocyanate prepolymer (C) being combined are in their respective specific ranges.