Coating Agent Gas Barrier Adhesion High Humidity
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Solution Overview
Problem
Existing gas barrier films face challenges in maintaining both excellent gas barrier properties and adhesion strength, especially in high-humidity environments, and have short usable times due to rapid curing agent reactions.
Innovation Solution
A coating agent comprising an acid group-containing polyurethane resin, a polyamine compound, an inorganic layered mineral, and an epoxy compound, which forms coating films with enhanced gas barrier properties and adhesion strength, and has a longer usable time due to slow-reacting epoxy compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic layered minerals are added to improve gas barrier property, then gas barrier property is improved, but adhesion strength and coating film cohesion strength are degraded
Solution Approach 1:
The patent uses a composite coating film comprising a water-soluble polymer, an aqueous polyurethane resin, and an inorganic layered mineral. The water-soluble polymer forms a matrix that binds the inorganic layered minerals, creating a composite structure that maintains both gas barrier properties and adhesion strength. The polyurethane resin component specifically addresses adhesion to base films while the inorganic layers provide the barrier function.
Solution Approach 2:
The patent specifies precise compositional parameters: the water-soluble polymer content is 30-80 mass% of total solids, the aqueous polyurethane resin is 10-50 mass%, and the inorganic layered mineral is 10-30 mass%. These parameter ranges are optimized to balance gas barrier performance with adhesion and cohesion strength, resolving the contradiction between these properties.
2Strength
If curing agents are added to improve adhesion strength, then adhesion strength is improved, but usable time is significantly shortened due to rapid reactions
Solution Approach 1:
The patent removes the need for separate curing agents by incorporating polyamine compounds directly into the aqueous polyurethane resin formulation. The polyamine groups react with isocyanate groups during film formation at controlled rates, providing adhesion enhancement without requiring additional curing agents that would cause rapid reactions and shorten usable time.
Solution Approach 2:
The polyamine compound acts as an intermediary that mediates between the polyurethane resin and the base film, providing adhesion enhancement through controlled chemical reactions. This intermediary approach allows for gradual reaction and adhesion development without the rapid reaction associated with traditional curing agents.
3Reliability
If metal foils or metal-deposited films are used to achieve excellent gas barrier property, then gas barrier property is improved, but stretching property deteriorates causing cracks
Solution Approach 1:
The patent uses a flexible polymer-based coating film instead of rigid metal foils or metal-deposited films. The water-soluble polymer and polyurethane resin matrix provides flexibility and stretchability, allowing the coating to deform without cracking while maintaining the gas barrier function through the laminated inorganic layered mineral structure.
Solution Approach 2:
The coating film is a composite material combining organic polymers (water-soluble polymer and polyurethane resin) with inorganic layered minerals. This composite structure provides both the flexibility of polymers and the gas barrier properties of inorganic layers, eliminating the brittleness of metal-based barriers.
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 achieves excellent gas barrier properties and sufficient adhesion strength in high-humidity environments, with a longer usable time, ensuring stable performance and improved lamination strength for packaging applications.
Implementation Method 1
gas barrier property that does not depend on humidity
Implementation Method 2
a coating agent which exhibits an excellent gas barrier property even in high-humidity atmospheres, can be used to form coating films having sufficient adhesion strength to other materials or sufficient coating film cohesion strength
Data Source
AI summary
A coating agent includes, as principal components: an aqueous polyurethane resin (A) including a polyurethane resin having an acid group and a polyamine compound, a water-soluble polymer (B), an inorganic layered mineral (C), and a compound (D) having an epoxy group.