Microencapsulated DCOIT Biocide Shell Permeability Control
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Solution Overview
Problem
Existing microencapsulated compositions of isothiazolone derivatives, such as DCOIT, face challenges with solubility issues in seawater and xylene, leading to instability and premature release, which affects their efficacy as biocides in marine antifouling coatings.
Innovation Solution
The development of microencapsulation processes using oil-in-water emulsion systems with hydrophilic shell materials that are impermeable to xylene but permeable to seawater, allowing for controlled release of DCOIT, incorporating partially hydrolyzed polyvinyl alcohol and phenolic resin, and dual-walled microcapsules with specific shell thickness and dopants to enhance stability and bio-efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If DCOIT is encapsulated in microcapsules for incorporation into marine paints, then in-can stability is improved, but the capsules must be essentially impermeable to xylene to prevent DCOIT leakage and reaction with paint binders
Solution Approach 1:
The patent employs microcapsule shells with controlled permeability characteristics that are essentially impermeable to xylene while maintaining flexibility for gradual release in aqueous environments. The shell material and thickness are specifically designed to prevent DCOIT leakage during paint storage and application.
Solution Approach 2:
The patent optimizes shell thickness and material composition parameters to achieve the desired permeability profile. By adjusting these parameters, the capsules maintain stability in xylene-based paints while enabling controlled release in seawater environments.
2Reliability
If the microcapsule shell is made permeable to seawater for gradual DCOIT release, then antifouling effectiveness is improved, but DCOIT may be leached away too quickly if the shell is too permeable to water
Solution Approach 1:
The patent carefully controls shell thickness and material hydrophilicity parameters to achieve optimal water permeability. This enables gradual DCOIT release over extended periods while preventing premature leaching that would render the paint vulnerable to microbial attack.
Solution Approach 2:
The microcapsule shells utilize porous or semi-permeable structures with controlled pore sizes and hydrophilic characteristics. These structures allow selective permeability to water molecules while maintaining mechanical integrity and controlling the release rate of DCOIT.
3Productivity
If hydrophilic shell materials are used to enhance saltwater release, then release rate is improved, but the capsules must remain impermeable to xylene for in-can stability
Solution Approach 1:
The patent creates microcapsule shells with locally optimized properties where hydrophilic regions facilitate water permeability and release, while the overall shell structure maintains xylene impermeability. This local quality differentiation enables simultaneous achievement of stability and controlled release.
Solution Approach 2:
The patent employs composite shell materials or multi-layer structures that combine hydrophilic components for water permeability with xylene-resistant barriers. This composite approach allows the shell to exhibit selective permeability - impermeable to xylene but permeable to water.
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 improved in-can stability and sustained release of DCOIT in marine environments, reducing leaching and interaction with paint binders, while maintaining antifouling effectiveness over an extended period.
Implementation Method 1
gradually release DCOIT to the surface of the marine coating in the presence of water and more particularly saltwater
Implementation Method 2
microencapsulation processes based upon oil-in-water emulsion systems
Implementation Method 3
DCOIT is an oily material with very low solubility in water that is liquid at temperatures at above about 40° C.
Implementation Method 4
The microcapsule shell or wall material is designed to be essentially impermeable to xlyene... The microcapsule shell should also be permeable to seawater
Data Source
AI summary
The present invention relates to microencapsulated compositions of isothiazolone derivatives and other water insoluble biocides or antifouling agents. In particular, the present invention relates to microencapsulated 4,5 dichloro 2 n-octyl-3(2H)-isothiazolone(DCOIT), useful in marine antifouling coatings and paints.