Positively Charged Microcapsule Shell for Fragrance Deposition
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Solution Overview
Problem
Current encapsulated perfume compositions fail to achieve effective deposition while maintaining good olfactive performance, with existing methods using toxic and corrosive agents for imparting a permanent positive charge to microcapsules, which is not commercially acceptable.
Innovation Solution
The development of encapsulated fragrance compositions featuring core-shell microcapsules with a positively charged shell formed from a mixture of difunctional polyisocyanates and a polyfunctional amine or alcohol, stabilized with a positively charged polymeric colloidal stabilizer, which remains constant and does not wash out, ensuring both stability and olfactive performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent positive charge is imparted to microcapsules using existing methods (e.g., dimethyl sulfate), then deposition on substrates is enhanced, but the process becomes toxic, corrosive, and commercially unacceptable
Solution Approach 1:
The invention extracts and eliminates the toxic quaternization step (dimethyl sulfate treatment) from the microcapsule modification process. Instead, it uses a cationic polymer coating applied to pre-formed microcapsules, achieving the same deposition enhancement without the harmful agents.
Solution Approach 2:
The invention introduces a cationic polymer as an intermediary substance that mediates between the microcapsule surface and the substrate. This polymer layer provides the positive charge needed for enhanced deposition without requiring direct contact with toxic quaternizing agents.
2Reliability
If microcapsules are coated with cationic polymers to achieve positive charge, then deposition is improved, but the stability and olfactive performance may be compromised
Solution Approach 1:
The invention optimizes parameters including the molecular weight of the cationic polymer (10,000-1,000,000), the amount of polymer added (0.1-10 times the weight of the microcapsule), and the pH conditions during coating to achieve the desired balance between positive charge density and olfactive performance stability.
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 microcapsules with a stable positive charge and excellent olfactive performance, enhancing deposition on surfaces without using toxic agents, thus addressing the commercial acceptability and effectiveness issues of prior art.
Implementation Method 1
the shell comprises a reaction product of a mixture of at least two at least difunctional polyisocyanates with a polyfunctional amine or alcohol
Implementation Method 2
the shell is formed around droplet of core material that is stabilized with a positively charged polymeric colloidal stabilizer
Implementation Method 3
the mixture of the at least two polyisocyanetes comprises at least one nonionic polyisocyanate and at least one anionically modified polyisocyanate
Data Source
AI summary
The invention relates to an encapsulated fragrance composition comprising at least one microcapsule dispersed in a dispersion medium, said at least one microcapsule comprising a fragrance oil core and a positively charged shell, which comprises a reaction product of at least one at least difunctional anionically modified isocyanate with an amine or alcohol, preferably a polyamine, and wherein the shell is formed around droplet of core material that is stabilized with a positively charged colloidal stabilizer. Furthermore, the invention relates to a process of formation of said encapsulated fragrance compositions.