One-Component Polyurethane Adhesive for Fast Film Lamination Curing
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Solution Overview
Problem
Existing one-component polyurethane adhesives based on aliphatic diisocyanates cure too slowly and are not suitable for high-temperature food contact and medical retort applications, while those with increased catalyst concentrations lead to quality issues and reduced open time.
Innovation Solution
A one-component polyurethane adhesive composition comprising an isocyanate terminated prepolymer, formed from a reaction mixture of toluene diisocyanate and polyether polyol, without a curing catalyst, which is storage stable and achieves rapid curing suitable for film lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aliphatic diisocyanates are used in one-component polyurethane adhesives, then toxicity and volatility are reduced, but curing speed becomes too slow for film lamination applications
Solution Approach 1:
The patent changes the chemical parameter by using aromatic polyisocyanates instead of aliphatic diisocyanates, which fundamentally alters the reaction rate. Aromatic polyisocyanates provide significantly faster curing speeds while maintaining acceptable safety profiles, directly resolving the contradiction between safety and curing speed.
Solution Approach 2:
The patent creates a composite adhesive system combining aromatic polyisocyanates with specific polyols and catalysts. This composite formulation achieves optimal balance between curing speed, adhesion properties, and safety characteristics, allowing fast curing without excessive toxicity or volatility.
2Speed
If catalyst concentration is increased to accelerate curing of aliphatic diisocyanate-based adhesives, then curing speed improves, but storage stability deteriorates due to secondary reactions
Solution Approach 1:
The patent changes the fundamental approach by switching from aliphatic diisocyanates to aromatic polyisocyanates. This parameter change allows the use of lower catalyst concentrations while achieving faster curing speeds, thereby maintaining storage stability. The aromatic polyisocyanate system inherently provides better stability characteristics that prevent excessive secondary reactions.
Solution Approach 2:
The patent employs a disposable catalyst system where the catalyst is present in low concentrations and is consumed during the curing process. This approach allows rapid curing without long-term stability issues, as the catalyst does not remain in excess to cause prolonged secondary reactions during storage.
3Speed
If catalyst concentration is increased to accelerate curing, then curing speed improves, but open time is reduced to unacceptable levels
Solution Approach 1:
The patent changes the chemical composition by using aromatic polyisocyanates with optimized catalyst concentrations. This parameter optimization allows the adhesive to maintain fast curing speeds while preserving sufficient open time for proper film assembly and lamination operations. The aromatic polyisocyanate system provides a more favorable kinetic profile that balances curing speed and open time.
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 composition provides excellent curing and open time, ensuring quick adhesion and stability for flexible film packaging, particularly in high-temperature food contact and medical retort applications.
Implementation Method 1
In the presence of atmospheric moisture, they cure in 10 to 60 minutes in the present of catalysts
Data Source
Figure 1
AI summary
The present invention relates to a one-component polyurethane adhesive composition for film lamination, in particular in food flexible packaging. Further, the present invention relates to method of manufacturing a laminate by using the one-component polyurethane adhesive composition and the laminate obtainable by the described method.