Microencapsulating Reactive Blowing Agents via In-Situ Polymerization
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Solution Overview
Problem
Current microencapsulation methods, such as single-shell processes using Complex Coacervation and In-Situ Polymerization, are inadequate for fully encapsulating reactive materials like methyl hydrogen silicone fluid, resulting in unencapsulated core material, leaky shells, and early reaction with other components, leading to poor shelf-life and handling issues.
Innovation Solution
A single-shell microencapsulation process via In-Situ Polymerization, where a difficult-to-encapsulate core material is suspended within a protective secondary core material, which is then encapsulated in a final polymerized shell, utilizing parameters like hydrophobicity differences to ensure complete protection and stability, allowing for the formation of dry, free-flowing microcapsules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-shell microencapsulation processes (Complex Coacervation or In-Situ Polymerization) are used to encapsulate reactive core materials like methyl hydrogen silicone fluid, then the process complexity is reduced, but the encapsulation effectiveness deteriorates resulting in unencapsulated core material, leaky shells, and poor shelf-life
Solution Approach 1:
The invention divides the encapsulation process into two distinct stages: first forming a protective pseudo-shell layer around the core material, then performing In-Situ Polymerization to create the final shell. This segmentation allows each stage to optimize for its specific function, achieving complete encapsulation without requiring complex multi-layer deposition processes.
Solution Approach 2:
The protective pseudo-shell layer is formed in advance before the In-Situ Polymerization step. This preliminary action protects the reactive core material during subsequent processing and ensures complete encapsulation by providing a stable substrate for the final shell formation, eliminating the need for complex multi-step deposition.
2Reliability
If multiple-layer shell deposition or multiple-process microencapsulation is performed to improve encapsulation effectiveness, then the reliability of encapsulation increases, but the process complexity and number of steps greatly increase
Solution Approach 1:
The invention merges the protective shell formation and final encapsulation into a single integrated two-stage process. The protective pseudo-shell layer and the final polymerized shell work together as a unified encapsulation system, achieving complete protection without requiring separate multi-layer deposition steps.
Solution Approach 2:
The encapsulation system uses composite structure combining the protective pseudo-shell layer (from core material and protective agents) with the final polymerized shell. This composite approach provides superior encapsulation effectiveness compared to single-material shells, while maintaining process simplicity through the two-stage methodology.
3Ease of operation
If conventional single-shell microencapsulation methods are used for reactive core materials, then the handling ease is improved, but the shelf-life deteriorates due to early reaction with other components
Solution Approach 1:
The protective pseudo-shell layer acts as a cushioning barrier formed beforehand to protect the reactive core material from premature reaction with other formulation components. This preliminary protection maintains both handling ease and extends shelf-life by preventing early expansion or degradation.
4Reliability
If the core material is highly reactive (e.g., methyl hydrogen silicone fluid), then the functional performance is improved, but the difficulty of encapsulation increases limiting available chemical microencapsulation processes
Solution Approach 1:
The protective pseudo-shell layer serves as an intermediary between the highly reactive core material and the external environment. This intermediate layer enables the use of simple In-Situ Polymerization for encapsulation by mediating the interaction between the reactive core and shell-forming agents, avoiding the need for complex processes like Complex Coacervation.
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
This method effectively encapsulates reactive materials, providing improved shelf-life and handling properties, preventing premature reaction with other components, and enabling their use in formulations like expandable sealants and adhesives with enhanced sealing and adhesion properties.
Implementation Method 1
the core material is at least slightly more hydrophobic than the protective secondary core material
Implementation Method 2
a single microencapsulation process is performed via In-Situ Polymerization
Data Source
AI summary
A method for microencapsulating a core material, such as a blowing agent, in a single shell which has demonstrated to be challenging to microencapsulate as an individual component with a single-shell wall deposition using conventional techniques. Single-shell microcapsules of the blowing agent can be formed, minimizing steps involved in the present microencapsulation technique. Also, microcapsules formed by this method provide increased performance in end-use products, including but not limited to characteristics such as product shelf-life, ease of use, and greater expansion properties. A method of making a coating formulation including the microcapsules is further provided, as well as a fastener including the coating.