Ionic Acrylate Microcapsule Slurry Leakage Resistance
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Solution Overview
Problem
Existing aqueous microcapsule suspensions face issues with storage stability due to leakage of the oil core and require pressure to release the oil phase, while also lacking resistance to oil phase leakage during storage.
Innovation Solution
An aqueous slurry containing oily medium-filled microcapsules with an ionic acrylate copolymer shell that forms around the oily medium, allowing for leak resistance during storage and spontaneous release upon drying without pressure, formed through a process involving a water-soluble mono-functional acrylate monomer and a multi-functional acrylate monomer in an emulsion polymerization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microcapsule suspensions are used, then the oil phase can be released upon pressure application, but the microcapsules leak oil core during storage and require pressure to release the oil phase
Solution Approach 1:
The patent changes the chemical composition parameters of the capsule wall by using specific copolymers (polyvinyl alcohol crosslinked with boron or persulfate ions) that exhibit different properties in aqueous versus dry states. This parameter change enables the wall to be permeable to oil during storage but impermeable when dry, automatically controlling oil release based on moisture content rather than requiring external pressure
Solution Approach 2:
The capsule wall properties are made dynamic rather than static - the polymer structure changes its permeability characteristics in response to environmental conditions (presence or absence of water). The wall transitions from a leak-resistant state in aqueous suspension to an oil-release state upon drying, providing adaptive functionality without external intervention
2Ease of operation
If polyvinyl alcohol crosslinked microcapsules are used, then automatic oil release occurs upon drying, but the storage stability of the suspension deteriorates due to oil core leakage
Solution Approach 1:
The patent applies different functional characteristics to different aspects of the capsule system: the capsule wall provides leak resistance during storage while maintaining the capability for automatic release upon drying. The crosslinking density and polymer composition are optimized to create localized properties that satisfy both contradictory requirements at different stages of product lifecycle
Solution Approach 2:
The capsule wall is designed with pre-established protective properties that prevent oil leakage during storage under aqueous conditions. The crosslinked polyvinyl alcohol structure provides a protective barrier during storage that is temporarily activated to prevent leakage, and then deactivates or transforms upon drying to enable automatic release
3Stability of the object's composition
If water-soluble vinyl monomer microcapsules are used, then stable homogenous dispersion is achieved, but the microcapsules require pressure to rupture and release the oil phase
Solution Approach 1:
The patent transforms the static capsule wall structure into a dynamic system that responds to environmental changes. The polyvinyl alcohol crosslinked structure maintains stability in aqueous dispersion but undergoes a transformation upon drying that enables automatic oil release without requiring external pressure application
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 achieves minimal leakage of the oily medium during storage, with less than 1% release in four weeks, and complete or near-complete release of the oily medium within six hours after drying, enhancing storage stability and application efficacy.
Implementation Method 1
Such microcapsules have been formed by interfacial polymerization wherein one monomer is in the oil phase and the other is in the aqueous phase. One phase is dispersed as droplets in the other and then polymerization proceeds at the oil-water interface to form a shell wall around the droplet.
Implementation Method 2
The microcapsules have an ionic acrylate copolymer that can provide for beneficial leak resistance of the oily-medium and yet can release the oily medium upon drying/removal of the aqueous medium.
Data Source
AI summary
An aqueous slurry composition containing microcapsules dispersed in an aqueous medium. The microcapsules contain an ionic acrylate copolymer shell encapsulating an oily medium. Upon drying, the microcapsules release the oily medium. The slurry is useful in delivering a variety of water-insoluble substances via an aqueous medium including cosmetic or agricultural agents.