Polyurethane Binder System Alkoxylated Diamine Curing
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Solution Overview
Problem
Two-component polyurethane binder systems used in food packaging face issues with toxic migration of monomeric polyisocyanates, leading to contamination and anti-sealing effects, requiring lengthy storage times to ensure compliance with regulatory limits, and existing solutions compromise on reactivity, pot life, or complexity.
Innovation Solution
A binder system utilizing a special polyol mixture containing at least one alkoxylated diamine to harden isocyanate-terminated polyurethane prepolymers, allowing for rapid chemical curing and minimizing migration of primary aromatic amines, while maintaining a long pot life for ease of processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional isocyanate-terminated polyurethane prepolymers with high concentrations of isocyanate monomers are used, then adhesive strength and bonding performance are improved, but migration of primary aromatic amines increases and curing time extends
Solution Approach 1:
The patent changes the chemical parameters of the hardener component by using alkoxylated diamines with specific molecular weights (50-500 g/mol) and alkoxylate ratios (1-10), which fundamentally alters the curing kinetics and migration behavior of the system, enabling rapid curing with minimal PAA migration
Solution Approach 2:
The patent creates a composite binder system combining isocyanate-terminated polyurethane prepolymers with alkoxylated diamine hardeners, where the synergistic interaction between components achieves both high adhesive strength and rapid curing with low migration
2Speed
If conventional metal catalysts or amine catalysts are used to accelerate curing, then curing speed is improved, but pot life is reduced and processing becomes difficult
Solution Approach 1:
The patent employs alkoxylated diamines that function as both hardener and curing accelerator, sacrificing some of the diamine's reactivity to achieve rapid curing without requiring separate catalyst systems, thereby maintaining long pot life for easy processing
Solution Approach 2:
The patent optimizes the molecular weight and alkoxylate ratio parameters of the diamine hardener to achieve ideal pot life characteristics, balancing reactivity for fast curing with stability during processing
3Object-affected harmful factors
If the amount of aromatic polyisocyanates is reduced to prevent migration, then toxicity is reduced, but reactivity is reduced and catalysts are required
Solution Approach 1:
The patent uses alkoxylated diamines as intermediary compounds that facilitate rapid curing of isocyanate prepolymers through a controlled reaction mechanism, enabling the system to achieve full cure with minimal free isocyanate and PAA migration without requiring additional catalysts
4Strength
If monomeric polyisocyanates migrate and react with fatty acid amides, then adhesive bonding is improved, but anti-seal effect occurs preventing uniform seal seams
Solution Approach 1:
The patent performs preliminary curing of the binder system using alkoxylated diamines to convert free isocyanate groups into bonded urea linkages before the lamination process, preventing subsequent migration and anti-seal effects during sealing operations while maintaining adhesive strength
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 binder system achieves rapid curing and low migration of primary aromatic amines, ensuring food packaging compliance within a shorter storage time, with a suitable pot life for industrial use, and produces strong adhesive bonds between various substrates.
Implementation Method 1
Upon contact with moisture, the isocyanate groups of the migrates are continuously converted to amino groups, transforming aromatic polyisocyanates into so-called primary aromatic amines (PAAs)
Implementation Method 2
A binder system utilizing a special polyol mixture containing at least one alkoxylated diamine to harden isocyanate-terminated polyurethane prepolymers, allowing for rapid chemical curing
Implementation Method 3
ensuring food packaging compliance within a shorter storage time, with a suitable pot life for industrial use, and produces strong adhesive bonds between various substrates
Data Source
AI summary
The present invention relates to a binder system which contains an isocyanate-terminated polyurethane prepolymer as the resin component and a polyol mixture as the curing agent, said polyol mixture containing at least one alkoxylated diamine. The invention also relates to the use of the binder system as an adhesive/sealing material, in particular as a laminating adhesive for food packaging.