Aqueous Multilayer Soft-Touch Coating for Low-VOC Wear Resistance
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Solution Overview
Problem
Conventional soft-touch coatings for 3C products contain high levels of VOCs, pose health risks due to solvent vaporization, and have fire hazards, necessitating the development of water-borne coatings with low VOC content and improved safety.
Innovation Solution
A multi-layer coating system comprising a first coating layer formed from an acrylic resin and hydroxyl functional acrylic resin, and a second coating layer formed from an aliphatic hydroxyl functional polyester polyurethane and water dispersible polycarbonate diol resin, which are applied to form a substrate coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional solvent-containing soft-touch coatings are used, then good hand feeling and fingerprint-proof effect are achieved, but VOC content becomes excessively high (600-800 g/L)
Solution Approach 1:
The patent changes the fundamental parameter of the coating system from solvent-based to water-based formulation. The first coating layer uses water-dispersible acrylic resin and the second coating layer uses water-dispersible polyester polyurethane, transforming the continuous phase from organic solvent to water, thereby reducing VOC content while maintaining coating performance
Solution Approach 2:
The patent employs a composite multi-layer coating system where the first coating layer (acrylic resin-based) provides adhesion and primer functions, while the second coating layer (polyester polyurethane-based) provides the soft-touch effect and fingerprint resistance. This composite approach allows each layer to be optimized for specific functions while both using water-based formulations to control VOC content
2Object-generated harmful factors
If water-borne coatings are used to reduce VOC, then health and safety improve, but coating performance and hand feeling may deteriorate
Solution Approach 1:
The patent uses a composite two-layer coating system where the first layer (water-based acrylic resin) provides adhesion and substrate preparation, while the second layer (water-based polyester polyurethane) delivers the desired soft-touch effect and fingerprint resistance. This composite structure ensures that water-based formulation can achieve both low VOC and high performance
Solution Approach 2:
The patent optimizes the formulation parameters of water-based coatings by selecting specific water-dispersible polymers with appropriate molecular weights, hydroxyl values, and curing ratios. The use of hydroxyl-functional acrylic resin and polyester polyurethane with controlled glass transition temperatures ensures the coating achieves good hand feeling and fingerprint-proof effect while maintaining water-based low-VOC characteristics
3Strength
If multi-layer coating system is applied, then adhesion and wear resistance improve, but coating complexity increases
Solution Approach 1:
The patent divides the coating system into two distinct functional layers: the first coating layer (acrylic resin-based) serves as an adhesive primer providing substrate bonding, while the second coating layer (polyester polyurethane-based) provides the soft-touch effect and wear resistance. This segmentation allows each layer to be optimized for its specific function, improving overall performance while keeping the formulation relatively simple
Data Source
AI summary
The present invention provides a multi-layer coating system comprising: (a) a first coating layer formed from a first coating composition; and (b) a second coating layer applied directly over at least a portion of the first coating layer and formed from a second coating composition. The present invention further provides a substrate coated with the multi-layer coating system.