Cross-Linked Polyurea and Polyurethane Capsules for Controlled Release
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Solution Overview
Problem
Existing polyurea and polyurethane capsules face issues such as low olfactory intensity, low stability, high toxicity, and poor deposition on target surfaces, with a need for improved mechanical strength and controlled release profiles in consumer products like laundry and personal care items.
Innovation Solution
A method involving the preparation of polyurea or polyurethane capsules through emulsifying an oil phase with a polyisocyanate and an aqueous phase with a cross-linking agent, followed by curing and purification, using specific cross-linking agents and capsule formation aids to enhance stability and deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polycondensation methods are used to prepare polyurea or polyurethane capsules, then the capsules can be formed with basic structural integrity, but the resulting capsules exhibit low olfactory intensity, low stability, high toxicity, and poor deposition on target surfaces
Solution Approach 1:
The patent changes the chemical parameters of the capsule wall by introducing cross-linking agents (polyamines or polyols) that react with the polyisocyanate to form polyurea or polyurethane networks with different molecular structures and properties. This cross-linking modifies the polymerization degree, network density, and chemical composition, thereby reducing toxicity while enhancing stability and mechanical strength
Solution Approach 2:
The patent creates composite capsule walls by combining polyisocyanate with cross-linking agents (polyamines for polyurea or polyols for polyurethane) to form multi-component polymer systems. These composite structures integrate the benefits of different materials: the structural framework from polyisocyanate, the stability and reduced toxicity from cross-linked networks, and improved surface properties for better deposition
2Ease of manufacture
If conventional polycondensation methods are used, then capsules can be formed, but they exhibit poor deposition on target surfaces
Solution Approach 1:
The patent modifies surface parameters of the capsules by controlling the cross-linking density and chemical composition of the capsule wall. The cross-linked polyurea or polyurethane networks create specific surface energies, roughness, and chemical functionalities that enhance adhesion to target surfaces like fabric or skin, while maintaining overall structural stability
Solution Approach 2:
The patent creates local quality differences within the capsule structure by having a core containing the active material (fragrance, pesticide, etc.) and a shell with cross-linked polyurea or polyurethane walls that have different properties optimized for specific functions: the core protects the active material while the cross-linked shell provides stability, controlled release, and improved surface deposition
3Duration of action of moving object
If standard polycondensation is used, then capsules can be prepared, but they show low olfactory intensity and poor controlled release profiles
Solution Approach 1:
The patent implements periodic or controlled release mechanisms through the cross-linked polyurea or polyurethane capsule walls. The network structure allows for gradual diffusion of active materials over time, creating sustained release profiles that extend the duration of action while controlling the rate and timing of release, thereby improving both longevity and effectiveness
Solution Approach 2:
The patent uses thin, cross-linked polyurea or polyurethane capsule walls that provide flexible yet stable encapsulation. These thin films allow for controlled permeation and diffusion of active materials while maintaining structural integrity, enabling sustained release over extended periods and enhancing olfactory intensity through controlled vapor release
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 method results in capsules with high perceived olfactory intensity, prolonged stability, low toxicity, and improved deposition on surfaces, suitable for consumer products like shampoos, conditioners, and fabric softeners.
Implementation Method 1
the polycondensation reaction will take place. Thus, the small droplets of the water-immiscible phase will be surrounded by the capsule wall formed by polycondensation of the isocyanate and the polyalcohol or polyamine as starting materials
Implementation Method 2
If the active material to be encapsulated is hydrophobic, it will be included in the water-immiscible phase, thereafter the two phases are mixed by high shear mixing to form an oil-in-water emulsion
Data Source
AI summary
Polyurea capsule compositions. A subset of these compositions contain a plurality of capsules and a capsule formation aid, in which each of the capsules contains a polyurea wall and an oil core; the polyurea wall is formed of a reaction product of a polyisocyanate and a cross-linking agent in the presence of the capsule formation aid; and the oil core contains an active material. The polyisocyante, cross-linking agent, and capsule formation aids are described herein. Also disclosed are methods of preparing polyurea capsule compositions, as well as consumer products containing one of these compositions.