Microcapsules Containing Algicide and Melamine-Formaldehyde Polymer

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Solution Overview

Problem

Existing microencapsulation methods for biocides like diuron in coating compositions face challenges with high leaching rates and environmental pollution due to water solubility, leading to reduced algae-toxic effects and stability issues.

Innovation Solution

The development of microcapsules containing biocides such as diuron, encapsulated with a melamine-formaldehyde polymer, using a process involving deposition, thermal treatment, and addition of urea to enhance stability and reduce leaching, with specific conditions for pH, temperature, and composition to achieve optimal particle size and leaching rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If water-soluble algicides like diuron are used in exterior paints, then the algicidal effect is initially effective, but the algicide leaches out upon contact with water, reducing long-term protection and causing environmental pollution

Engineering Contradiction:

Improvealgicidal effectivenessVSAvoidalgicide leaching

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The algicide is segmented into individual microcapsules, each containing a controlled amount of active substance. This segmentation allows the algicide to be released in controlled amounts from each capsule rather than all at once, reducing leaching while maintaining effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The algicide is nested within the microcapsule structure, with the active substance enclosed inside a protective polymer shell. This nested configuration prevents direct contact between the water-soluble algicide and external water, eliminating leaching while preserving the algicidal effect until controlled release is triggered.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Loss of substance

If microencapsulation is used to reduce algicide leaching, then environmental pollution and leaching are reduced, but high levels of free formaldehyde are generated, complicating commercial use

Engineering Contradiction:

Improvealgicide leachingVSAvoidfree formaldehyde

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The formaldehyde content is controlled by adjusting the formaldehyde-to-melamine ratio in the polymer synthesis, maintaining it below 0.5 wt% through precise parameter control of the encapsulation process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The formaldehyde that would normally be a harmful byproduct is converted into a beneficial crosslinking agent during polymer synthesis, forming stronger polymer bonds that improve capsule stability while minimizing free formaldehyde residue through controlled reaction conditions.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If high concentrations of biocides are applied to prevent mold growth and ensure stability, then protection effectiveness is improved, but environmental pollution increases

Engineering Contradiction:

Improveprotection effectivenessVSAvoidenvironmental pollution

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The biocide is released periodically from the microcapsules rather than all at once, providing sustained low-level protection. This periodic release mechanism maintains effective concentrations over time while using lower overall biocide amounts, reducing environmental pollution.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The biocide is pre-loaded into microcapsules at controlled concentrations during manufacturing, allowing for precise dosing and distribution. This preliminary action ensures that only the necessary amount of biocide is applied and released over time, improving protection efficiency while minimizing environmental impact.

Inventive Principle:

Principle #10Preliminary action

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 resulting microcapsules exhibit significantly reduced leaching rates (0.1-3.0 ppm after 24 hours) and prolonged durability, maintaining effective algae-toxicity and stability, allowing for longer protection of coating compositions with lower biocide concentrations.

Implementation Method 1

a process involving deposition, thermal treatment, and addition of urea to enhance stability

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

microcapsules containing an algicide and a melamine-formaldehyde polymer

Methodology Applied

Scientific EffectPolymerization: Chemical Bonding

Implementation Method 3

significantly reduced leaching rates (0.1-3.0 ppm after 24 hours) and prolonged durability

Methodology Applied

Scientific EffectControlled release: Diffusion Barrier

Data Source

PatentEP2993982B1Microcapsules containing an algicide and a melamine-formaldehyde polymer

Publication Date: 2019.07.17 LANXESS DEUTSCHLAND GMBH

AI summary

The present invention relates to microcapsules containing one or more biocides such as in particular algicides and at least one melamine-formaldehyde polymer, a method for the production thereof, and the use thereof for protecting technical materials.