Multilayer Coating for Flexible Substrates
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Solution Overview
Problem
Current methods for producing multilayer coatings on substrates fail to achieve a balance between high optical quality, mechanical resistance, and flexibility, particularly on flexible substrates like foam materials used in the footwear industry, where abrasion and stone chip resistance are critical.
Innovation Solution
A process involving a two-component aqueous basecoat and clearcoat composition, using a polyurethane resin with specific properties and a hydrophilically modified polyisocyanate, applied in a wet-on-wet manner to create a multilayer coating that enhances both optical appearance and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a coating is applied to achieve high optical quality and matting effect, then the visual appearance is enhanced, but the mechanical resistance and flexibility may be compromised
Solution Approach 1:
The patent employs a two-component coating system combining polyurethane resin with hydrophilically modified polyisocyanate. This composite material formulation enables simultaneous achievement of high optical quality, matting effect, and mechanical resistance. The specific component ratios and chemical composition create a synergistic effect where neither component alone could provide all required properties.
Solution Approach 2:
The patent specifies precise parameter ranges for the coating components, including polyurethane resin with hydroxyl number of 20-40 mg KOH/g and acid number of 10-30 mg KOH/g, and polyisocyanate with isocyanate content of 8-18 wt.%. By optimizing these chemical parameters, the coating achieves the desired balance between optical properties and mechanical resistance.
2Adaptability or versatility
If a coating is applied to achieve high flexibility on flexible substrates, then the coating can withstand deformation stresses, but the mechanical resistance to abrasion and stone chips may be reduced
Solution Approach 1:
The two-component system creates a composite coating structure where the polyurethane resin provides flexibility and the hydrophilically modified polyisocyanate enhances mechanical resistance. The chemical interaction between components forms a crosslinked network that simultaneously delivers both flexibility for deformation accommodation and resistance to external mechanical attacks.
Solution Approach 2:
The coating exhibits different property profiles in different aspects: high flexibility in terms of deformation capability and high mechanical resistance in terms of abrasion and stone chip resistance. This local quality differentiation is achieved through the specific molecular structure and crosslinking density of the composite coating system.
3Object-generated harmful factors
If a two-component aqueous coating composition is used, then ecological profile is improved, but the process complexity increases
Solution Approach 1:
The patent employs an aqueous-based coating system instead of organic solvent-based systems, using water as the dispersion medium. This hydraulic approach replaces harmful organic volatiles with water, significantly improving the ecological profile. The aqueous dispersion contains the polyurethane resin and other components in water, enabling eco-friendly application and drying processes.
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 resulting multilayer coating exhibits excellent optical quality, high matting effect, and enhanced mechanical resistance and flexibility, making it suitable for applications requiring durability and aesthetic appeal, such as shoe soles.
Implementation Method 1
a base component (b.1) and a hardener component (b.2), wherein the base component (b.1) contains (1) at least one polyurethane resin with a hydroxyl number of 15 to 100 mg 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 portion consisting of at least one polyurethane resin, the polyurethane resin portion having a gel content of at least 50%, having its glass transition at a temperature of less than -20 °C, having its melting transition at a temperature of less than 100 °C, and having a proportion of the polyurethane resin in the dispersion of 15 to 60% by weight, based on the total amount of the dispersion, and (3) at least one color and/or effect pigment, and (b.2) a hardener component containing (4) at least one hydrophilically modified polyisocyanate with an isocyanate content of 8 to 18% by weight
Data Source
AI summary
The present invention relates to a method for producing a multilayer coating (M) on a substrate (S), which comprises the following steps: (I) producing a base coat (B) on the substrate by applying an aqueous base coating (b) to the substrate (S), wherein the base coating is a two-component coating composition, and (II) producing a varnish coat (K) directly on the base coat (B) by applying an aqueous varnish (k) directly to the base coat (B), wherein the varnish is a two-component coating composition. The present invention also relates to the multilayer coatings thus produced and to the use thereof.