Formaldehyde-Free Microcapsule Wall via Melamine-Aldehyde Polymerization
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Solution Overview
Problem
There is a need for formaldehyde-free core-shell microcapsules that offer superior stability and performance in perfumery applications, as existing formaldehyde-based microcapsules contain residual formaldehyde due to unreacted precursors or decomposition, posing regulatory concerns and unsatisfactory performance in industrial applications.
Innovation Solution
A process for preparing formaldehyde-free core-shell microcapsules involving the reaction of melamine or a mixture of melamine with C1-4 compounds, glyoxal, C4-6 2,2-dialkoxyethanal, and a protic acid catalyst, followed by forming an oil-in-water dispersion with specific cross-linkers and optional additives, to create microcapsules with enhanced stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If formaldehyde-based aminoplast microcapsules are used, then stability and product delivery performance are improved, but residual formaldehyde content increases causing regulatory concerns
Solution Approach 1:
The patent removes formaldehyde from the microcapsule wall composition while maintaining the aminoplast structure. The wall is formed using melamine and alternative aldehydes (acetaldehyde, propionaldehyde, butyraldehyde) or ketones (acetone, butanone) instead of formaldehyde, thereby extracting the harmful substance while preserving the functional benefits of formaldehyde-based aminoplast microcapsules.
Solution Approach 2:
The patent combines melamine with alternative aldehydes or ketones to form a new aminoplast polymer composition that merges the structural advantages of melamine-formaldehyde with the safety benefits of formaldehyde-free alternatives. This creates a hybrid material that achieves both regulatory compliance and performance requirements.
2Object-affected harmful factors
If formaldehyde-free microcapsules are prepared using prior art methods, then residual formaldehyde is eliminated, but stability performance deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the microcapsule wall by changing the aldehyde/ketone component while maintaining the melamine base. This parameter change eliminates formaldehyde while the specific ratios and combinations of alternative aldehydes/ketones are optimized to restore and enhance stability performance.
Solution Approach 2:
The patent creates a composite aminoplast material combining melamine with multiple alternative aldehydes and ketones. This composite approach allows the material to achieve both formaldehyde-free status and improved stability through the synergistic effects of different molecular components in the polymer structure.
3Object-affected harmful factors
If melamine and alternative aldehydes/ketones are reacted to form microcapsule walls, then formaldehyde-free microcapsules are produced, but manufacturing complexity increases
Solution Approach 1:
The patent develops a universal microencapsulation process that can use melamine with various alternative aldehydes and ketones interchangeably. The same general reaction conditions, catalyst systems, and processing parameters apply regardless of which specific alternative aldehyde or ketone is used, simplifying manufacturing despite the variety of possible formulations.
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 resulting microcapsules demonstrate superior stability and performance compared to prior art formaldehyde-free microcapsules, ensuring effective delivery of volatile compounds like perfumes while meeting regulatory requirements by eliminating residual formaldehyde.
Implementation Method 1
preparing an oligomeric composition comprising the reaction product of, or obtainable by reacting together: a polyamine component in the form of melamine or of a mixture of melamine and at least one C1-4 compound comprising two NH2 functional groups; an aldehyde component in the form of a mixture of glyoxal, a C4-6 2,2-dialkoxy-ethanal and optionally a glyoxalate; and a protic acid catalyst
Implementation Method 2
at least a cross-linker selected amongst: A) C4-C12 aromatic or aliphatic di- or tri-isocyanates and their biurets, triurets, trimers and trimethylol propane-adduct; and/or B) a di- or tri-oxiran compounds
Implementation Method 3
preparing an oil-in-water dispersion, wherein the droplet size is comprised between 1 and 600 μm, and comprising: an oil; a water medium; at least an oligomeric composition as obtained in step 1); at least a cross-linker; heating said dispersion; cooling said dispersion
Data Source
AI summary
The present invention relates to water-dispersible core-shell microcapsules essentially free of formaldehyde. In particular it concerns core-shell microcapsules having a shell obtained by reacting polyisocyanates or polyoxirans cross-linkers and oligomeric compositions which are the reaction products between a polyamine component and a particular mixture of glyoxal and a C4-6 2,2-dialkoxy-ethanal. The present invention also utilizes the invention's core-shell microcapsules as part of a perfuming composition or of a perfuming consumer product.