Radiation-Curable Water-Based Coating for Wrinkle-Free Color Sampling
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Solution Overview
Problem
Existing low VOC or zero VOC water-based polyurethane coatings for color sampling display products face challenges in providing mechanical integrity and aesthetic appeal on untreated paper substrates, as they tend to cause wrinkling, buckling, or curling due to water absorption, and require impractical industrial hygiene measures for reactive diluents.
Innovation Solution
A radiation-curable acrylic coating composition is applied to an untreated paper substrate, comprising a water-based polymer and a support polymer, cured using electron beam radiation to form an interpenetrating network of crosslinks, which maintains mechanical integrity and prevents unwanted substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If water-based polyurethane coatings are applied to untreated paper substrates, then VOC content is reduced, but the paper substrate wrinkles, buckles or curls due to water absorption
Solution Approach 1:
The patent changes the chemical composition parameters of the coating system by using a hybrid formulation combining water-based polyurethane dispersion with reactive diluents (acrylates or vinyl ethers). This parameter change allows the coating to maintain low VOC content while achieving rapid curing that prevents water-induced substrate deformation
Solution Approach 2:
The patent replaces the traditional thermal drying mechanism with radiation-curable (UV or electron beam) curing. This substitution enables rapid crosslinking of the coating film before water can penetrate and deform the paper substrate, thereby maintaining substrate shape integrity while keeping VOC content low
2Ease of operation
If reactive diluents are used to reduce viscosity of pre-crosslinked polyurethane, then coating applicability is improved, but industrial hygiene measures become extensive and impractical
Solution Approach 1:
The patent modifies the molecular weight and functional group parameters of the reactive diluents, selecting acrylates or vinyl ethers with appropriate chain lengths and reactivity. This parameter optimization achieves adequate viscosity reduction for coating application while maintaining safety profiles that do not require extensive industrial hygiene measures
3Strength
If pre-crosslinked polyurethane is prepared with large amount of monomers, then crosslinking density is improved, but prepolymer blend viscosity becomes highly viscous and cannot be easily dispersed in water
Solution Approach 1:
The patent segments the crosslinking process into two stages: first forming a water-dispersible polyurethane prepolymer with moderate crosslinking density, then adding reactive diluents that provide additional crosslinking functionality. This segmentation allows the prepolymer to remain sufficiently fluid for water dispersion while achieving high final crosslinking density through the second stage
Solution Approach 2:
The patent creates a composite coating system combining water-based polyurethane dispersion with reactive diluent components. This composite formulation achieves high crosslinking density through the synergistic interaction between the polyurethane prepolymer and reactive diluents, while maintaining adequate viscosity for dispersion and application
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 a color sampling display product with mechanical integrity and aesthetic appeal, preventing substrate wrinkling or curling while minimizing VOC content and industrial hygiene concerns, and achieving rapid curing rates.
Implementation Method 1
using electron beam radiation to cure the applied coating composition onto the first surface of the paper substrate, thereby forming an interpenetrating network of crosslinks between the one or more polymers in the coating composition
Data Source
AI summary
A color sampling display product is provided that includes a radiation-curable water-based coating composition applied to a substrate, and shows mechanical integrity and aesthetic appeal.