Cyclic Carbonate Polyurethane Coatings for Food Containers
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Solution Overview
Problem
Current container coating compositions using polyurethanes derived from polyisocyanates pose health risks and are difficult to work with, leading to reluctance in using them for food-contact applications, while alternatives like bisphenol A-based epoxy resins are perceived as harmful to human health.
Innovation Solution
A coating composition featuring a film-forming resinous material formed from the reaction product of a cyclic carbonate group-containing material and a polyamine, optionally with a curing agent and liquid diluent, which is applied to containers to provide a safe, adhesive, and flexible coating that is free from the drawbacks of polyisocyanates and bisphenol A-based polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyisocyanates are used to make polyurethanes as replacements for bisphenol A-containing polymers, then the coating can provide good overall properties, but the coating poses health risks and is difficult to work with
Solution Approach 1:
The patent extracts and eliminates the harmful polyisocyanate component from the polyurethane synthesis process. Instead of using polyisocyanates, the invention uses alternative chemistry (cyclic carbonates reacting with water or alcohols) to produce the desired polyurethane coating without the toxic intermediary, thereby maintaining coating performance while removing health risks
Solution Approach 2:
The patent introduces cyclic carbonate compounds as intermediary substances that can be safely handled and stored. These cyclic carbonates serve as safe precursors that convert to the necessary polyurethane components during the coating process, replacing the dangerous polyisocyanate intermediaries while maintaining the desired coating properties
2Reliability
If polyisocyanates are used to make polyurethanes, then the coating can provide good overall properties, but the coating is difficult to work with
Solution Approach 1:
The patent removes the problematic polyisocyanate component from the formulation, eliminating the associated handling difficulties, safety precautions, and processing complications while retaining the beneficial coating properties through alternative chemical pathways
3Reliability
If bisphenol A-based epoxy resins are used for container coatings, then the coating has good adhesion and flexibility, but the coating is perceived as harmful to human health
Solution Approach 1:
The patent extracts and eliminates bisphenol A from the coating formulation entirely, replacing it with alternative polymer chemistry (polyurethanes from cyclic carbonates) that achieves the same functional properties (adhesion, flexibility, durability) without the health concerns associated with bisphenol A exposure
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 solution provides a safe, effective, and flexible coating for food and beverage containers that is free from health hazards associated with polyisocyanates and bisphenol A, ensuring good adhesion and resistance to degradation, while being suitable for food contact.
Implementation Method 1
a film-forming resinous material comprising a functional group-containing reaction product of: (i) a cyclic carbonate group-containing material, (ii) a polyamine
Data Source
AI summary
A coating composition for application to the surface of a container comprising:(a) a film-forming resinous material comprising a functional group-containing reaction product of:(i) a cyclic carbonate group-containing material,(ii) a polyamine;(b) a curing agent reactive with functional groups of (a);(c) a liquid diluent.