Aqueous Polyurethane Basecoat for Flexible Substrates
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Solution Overview
Problem
Current coatings for flexible substrates, such as shoe soles, face challenges in achieving a balance between high optical quality, mechanical resistance, and flexibility, particularly in resisting abrasion and stone chips, while also being environmentally friendly.
Innovation Solution
Aqueous two-component basecoat comprising a polyurethane resin with specific hydroxyl and acid numbers, a polyurethane dispersion with high gel content, and hydrophilically modified polyisocyanate, applied directly to the substrate for thermal-chemical curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied to flexible foam substrates to achieve high optical quality and mechanical resistance, then the visual appearance and durability are improved, but the flexibility and elasticity of the substrate are compromised
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the chemical composition parameters of the coating system. Specifically, it uses polyurethane resins with controlled hydroxyl numbers (15-100 mg KOH/g) and acid numbers (10-50 mg KOH/g), along with specific polyisocyanate compounds, to create a coating that achieves both mechanical resistance and flexibility through optimized chemical parameters
Solution Approach 2:
The patent employs composite materials by combining multiple components in a multi-component system: polyurethane resin, polyisocyanate compound, and water, forming a complex coating composition that integrates the benefits of different materials to achieve both durability and flexibility simultaneously
2Strength
If a coating is applied to achieve high mechanical resistance against abrasion and stone chips, then the durability is improved, but the flexibility required for deformation stress resistance is reduced
Solution Approach 1:
The patent uses parameter changes by selecting polyurethane resins with specific hydroxyl numbers (15-100 mg KOH/g) and acid numbers (10-50 mg KOH/g), which control the coating's mechanical properties to achieve both strength and flexibility through optimized chemical composition parameters
Solution Approach 2:
The patent introduces water as an intermediary component in the coating system. Water acts as a flexible agent that maintains the coating's elasticity and ability to deform with the substrate while still providing mechanical resistance, preventing the coating from becoming too rigid
3Reliability
If conventional coatings are used to achieve good mechanical properties, then durability is improved, but environmental friendliness is worsened
Solution Approach 1:
The patent replaces traditional organic solvent-based coating systems with an aqueous-based system. By using water instead of organic solvents as the liquid carrier, the coating achieves good mechanical properties while eliminating the harmful environmental effects associated with organic solvent evaporation and disposal
Solution Approach 2:
The patent changes the fundamental parameter of the coating system from organic solvent-based to water-based. This parameter change enables the coating to maintain mechanical stability while improving environmental friendliness, as water is environmentally benign and can be easily disposed of or evaporated without harmful effects
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 solution provides coatings with excellent optical quality, high mechanical resistance, and flexibility, enhancing the durability of substrates against external mechanical influences like abrasion and stone chips, while maintaining a favorable ecological profile.
Implementation Method 1
applied directly to the substrate for thermal-chemical curing
Implementation Method 2
at least one aqueous dispersion (2) containing water and a polyurethane resin portion
Data Source
AI summary
The invention relates to an aqueous two-component base paint (b) containing (b.1) a main component containing (1) at least one polyurethane resin with a hydroxyl number of 15 to 100 KOH/g and an acid number of 10 to 50 mg KOH/g, (2) at least one aqueous dispersion containing water and a polyurethane resin content consisting of at least one polyurethane resin, wherein the polyurethane content has a gel content of at least 50%, a glass transition temperature below -20 °C, and a melt transition temperature below 100 °C, and (3) at least one dying and/or effect-producing pigment, said at least one pigment (3) being used in the form of at least one pigment paste which contains at least one polyurethane resin (1) as the paste resin, and (b.2) a curing component containing (4) at least one hydrophilically modified polyisocyanate (4) with an isocyanate content of 8% to 18%.