Microcapsules Reducing OIT Leaching via Composite Melamine-Formaldehyde Shells
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Solution Overview
Problem
Existing microencapsulated biocides, particularly those containing 2-n-octyl-4-isothiazolin-3-one (OIT), suffer from significant leaching issues, which affect their effectiveness and durability in technical materials.
Innovation Solution
The development of microcapsules using a melamine-formaldehyde polymer as the capsule material, incorporating OIT and/or 3-iodo-2-propynyl-butyl-carbamate (IPBC) with specific weight ratios, which reduces the leaching behavior of OIT and maintains biocidal efficacy by slow release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OIT is enclosed in microparticles made of resin, then biocidal protection is provided, but leaching behavior of OIT is significant
Solution Approach 1:
The patent uses composite capsule material consisting of melamine-formaldehyde polymer combined with other polymers (acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, or carboxymethyl cellulose) to create a multi-component shell that reduces OIT leaching while maintaining biocidal protection. This composite structure provides synergistic effects that prevent OIT release more effectively than single polymers.
Solution Approach 2:
The patent optimizes specific parameters including the weight ratio of melamine-formaldehyde polymer to other polymers (1:4 to 4:1), capsule particle size (0.3 to 100 μm, preferably 5 to 80 μm), and OIT content (0.1 to 10% by weight based on capsule weight) to achieve reduced leaching behavior while maintaining effective biocidal activity.
2Reliability
If capsule wall material is reduced to increase active ingredient content, then biocidal effectiveness is improved, but leaching behavior worsens
Solution Approach 1:
The patent maintains optimal leaching behavior even with reduced capsule wall material by precisely controlling the composition ratio within the composite material and the OIT content percentage, allowing higher active ingredient loading without proportionally increasing leaching.
Solution Approach 2:
The multi-polymer composite structure provides enhanced barrier properties that allow thinner wall sections while maintaining leaching resistance, enabling higher OIT content to be encapsulated effectively.
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 microcapsules exhibit improved leaching behavior and prolonged action, allowing for effective protection of technical materials with reduced active ingredient usage, while maintaining high biocidal effectiveness against a broad spectrum of fungi.
Implementation Method 1
The term melamine-formaldehyde polymers preferably refers to resins in which melamine has been polycondensed with formaldehyde under suitable conditions
Implementation Method 2
the leaching behavior of OIT from the microparticles can be significantly reduced... the active ingredient remains in the material so that it can be used in correspondingly low concentrations. In practical use, the biocide is released only slowly.
Data Source
AI summary
Microcapsules containing a) at least one melamine-formaldehyde polymer as capsule material and b) at least b1) OIT and b2) propiconazole and/or 3-iodo-2-propynyl butylcarbamate (IPBC) as biocide, characterized in that the weight ratio of OIT to the sum of propiconazole and/or IPBC is 5 : 1 to 1 : 5, preferably 1 : 1 to 1 : 5, in particular 1 : 1.5 to 1 : 3.