Polyurethane Coating Agent for Recyclable Paper Gas Barriers
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Solution Overview
Problem
Conventional methods of laminating polyurethane layers on paper substrates to enhance gas barrier properties result in high polyurethane resin content, making recycling unsuitable, while single-layer laminates may compromise gas barrier effectiveness due to moisture permeation.
Innovation Solution
A coating agent comprising a polyurethane resin derived from a reaction between an isocyanate group-terminated prepolymer and a chain extender, with specific components like xylylene diisocyanate and short chain diols, and a thickener, applied to paper substrates to form a polyurethane layer with enhanced gas barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyurethane layer is laminated on a paper substrate to provide gas barrier properties, then gas barrier performance is improved, but the amount of polyurethane resin increases making recycling difficult
Solution Approach 1:
The patent changes the chemical composition parameters of the polyurethane resin by using specific components (polyester polyol with 2,000-10,000 molecular weight, polyether polyol with 500-2,000 molecular weight, and polyamine with 2-6 carbon atoms) to achieve optimal gas barrier properties with reduced resin content, enabling both functionality and recyclability
Solution Approach 2:
The patent creates a composite polyurethane resin system combining multiple polyols and polyamines in specific ratios to achieve superior gas barrier properties while maintaining lower overall resin content, facilitating both performance and recycling compatibility
2Loss of substance
If the polyurethane layer is reduced to one layer to facilitate recycling, then resin content is reduced, but moisture permeation increases compromising gas barrier effectiveness
Solution Approach 1:
The patent optimizes the chemical parameters of the polyurethane resin (using specific molecular weight ranges for polyols and specific carbon atom counts for polyamines) to enhance the barrier properties of a single layer, allowing effective gas barrier performance with reduced resin content
Solution Approach 2:
The patent focuses on improving the local quality and molecular structure of the polyurethane resin itself rather than increasing layer thickness, using specifically selected polymeric components with optimal properties to achieve enhanced barrier performance in a thin single layer
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 agent effectively laminates a polyurethane layer on paper substrates, providing excellent gas barrier properties without excessive resin content, suitable for recycling and resistant to moisture permeation.
Implementation Method 1
a coating agent obtained by water-dispersing a polyurethane resin and a thickener
Implementation Method 2
applied to the paper substrate and dried to laminate a first layer
Implementation Method 3
the polyurethane resin is a secondary reaction product of an isocyanate group-terminated prepolymer and a chain extender
Implementation Method 4
the viscosity at 25° C. of the coating agent is 50 mPa·s or more
Data Source
AI summary
In a coating agent obtained by water-dispersing a polyurethane resin, the polyurethane resin is a secondary reaction product of an isocyanate group-terminated prepolymer and a chain extender. The isocyanate group-terminated prepolymer is a primary reaction product of a polyisocyanate component containing a xylylene diisocyanate and/or a hydrogenated xylylene diisocyanate, and an active hydrogen group-containing component containing a short chain diol having 2 to 6 carbon atoms and an active hydrogen compound having a hydrophilic group; and the viscosity at 25° C. of the coating agent is 50 mPa·s or more.