Laminating Adhesive Composition With Low Free Monomer Migration
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Solution Overview
Problem
Solvent-based laminating adhesives with high levels of free monomeric isocyanate pose safety and regulatory challenges, particularly in food packaging applications, necessitating a high-performing adhesive with excellent adhesion, fast curing, and low aromatic species migration.
Innovation Solution
A solvent-based adhesive composition comprising an isocyanate component with less than 1 wt.% aromatic-based isocyanate and an isocyanate reactive component containing phosphate ester polyol and polyester polyol, which reduces aromatic species migration while maintaining adhesion and curing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic isocyanate is used in solvent-based laminating adhesives, then adhesion performance and curing speed are improved, but free monomer level increases compromising safety and food safety
Solution Approach 1:
The patent changes the chemical composition parameters by using aliphatic and cycloaliphatic isocyanates instead of aromatic isocyanates, thereby reducing the free monomer level while maintaining adhesion performance and curing speed through optimized component ratios and molecular structure selection
Solution Approach 2:
The patent employs a composite adhesive system combining multiple polyol components (polyester polyol, polyether polyol, and hydroxyl-functionalized compound) with polyisocyanate, creating a multi-component formulation that achieves both low free monomer content and high performance through synergistic interactions among components
2Productivity
If aromatic isocyanate is used to achieve fast curing, then curing speed is improved, but aromatic species migration increases violating regulatory standards
Solution Approach 1:
The patent changes the chemical nature of isocyanate from aromatic to aliphatic and cycloaliphatic types, fundamentally altering the molecular structure to eliminate aromatic rings and their associated migration issues while preserving the reactive functionality needed for fast curing through optimized NCO index and component formulation
3Strength
If high levels of free monomeric isocyanate are present, then adhesion performance is improved, but operation safety and food safety are compromised
Solution Approach 1:
The patent optimizes the free monomer content parameter by selecting appropriate polyisocyanate molecular weights and structures (aliphatic and cycloaliphatic) that inherently provide lower free monomer levels, while compensating for any performance loss through adjusted component ratios and the inclusion of reactive diluents that participate in the curing reaction
Solution Approach 2:
The patent introduces hydroxyl-functionalized compounds and polyols as intermediary substances that react with isocyanate groups to form urethane linkages, thereby reducing free monomeric isocyanate content while maintaining adhesion strength through the formation of crosslinked polymer networks that provide mechanical bonding
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 adhesive achieves strong bond strength and fast curing with minimal migration of undesirable aromatic amines, meeting safety and regulatory standards for food packaging applications.
Implementation Method 1
The isocyanate component and the isocyanate reactive component are combined in a predetermined ratio, thereby forming a curable adhesive composition
Implementation Method 2
The solvent is evaporated from the applied adhesive composition
Data Source
AI summary
A solvent based adhesive composition comprising at least one isocyanate component comprising an aromatic-based isocyanate wherein the weight of the free monomeric isocyanate is less than 1 wt. % based on the weight of the isocyanate component, and at least one isocyanate reactive component comprising at least one phosphaste ester polyol is disclosed. A procedure for making the adhesive as well as a laminate partially made from the adhesive and a procedure for making the laminate are also disclosed.