Hydrophobic Polyurethane Coating for Water-Soluble Active Ingredient Crystals
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Solution Overview
Problem
Current methods for encapsulating water-soluble active ingredients in solid crystalline form fail to provide a stable, uniformly coated, and reproducible hydrophobic layer, leading to issues like leaching and reduced effectiveness under humid conditions.
Innovation Solution
A process involving the uniform distribution of active ingredient crystals in an organic solvent with a dispersing aid, followed by the addition of a polymer former and crosslinking agent to form a polyurethane layer, ensuring a defined and reproducible coating that reduces water solubility and prevents leaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-soluble active ingredients are formulated as stable suspensions, then application effectiveness is improved, but recrystallization occurs when temperature changes and leaching occurs under humid conditions
Solution Approach 1:
The patent introduces a hydrophobic coating layer as an intermediary barrier between the water-soluble active ingredient and the external environment. This coating prevents direct contact between water and the active ingredient, thereby preventing leaching while maintaining suspension stability. The coating acts as a protective mediator that allows the active ingredient to remain in solid crystalline form without dissolving under humid conditions.
Solution Approach 2:
The patent changes the physical-chemical parameters of the active ingredient by coating it with hydrophobic materials. This coating modifies the surface properties and reduces water solubility without changing the bulk crystalline structure. The coating thickness and composition are controlled to achieve the desired balance between stability and controlled release.
2Duration of action of moving object
If mechanical compaction is used to address solubility issues, then water absorption is delayed, but solubility cannot be significantly influenced
Solution Approach 1:
The hydrophobic coating serves as an intermediary layer that provides both mechanical barrier properties and chemical hydrophobicity. This allows precise control over solubility parameters while achieving the desired delay in water absorption. The coating thickness and composition can be precisely controlled to achieve target solubility reduction.
3Reliability
If coating in fluidized bed or coating pans is used, then hydrophobic layer is formed, but coating mass distribution is inhomogeneous and overall coating thickness is limited
Solution Approach 1:
The patent replaces mechanical coating methods (fluidized bed, coating pans) with a chemical approach using polymeric MDI and crosslinking agents. The coating is formed through chemical reaction rather than mechanical application, ensuring uniform distribution and controlled thickness. The in-situ polymerization and crosslinking process ensures homogeneous coating mass distribution throughout the particle.
Solution Approach 2:
The patent creates a composite coating structure combining polymeric MDI, crosslinking agents, and hydrophobic additives. This composite approach provides both uniform distribution and enhanced hydrophobic properties. The crosslinked polymer network ensures homogeneous coating while the hydrophobic components provide the necessary water repellency.
4Reliability
If microencapsulation in aqueous environment is used, then encapsulation is achieved, but water-soluble active ingredients are dissolved and escape encapsulation
Solution Approach 1:
The patent uses a hydrophobic coating as an intermediary barrier that prevents water from reaching the water-soluble active ingredient. This coating layer acts as a protective mediator that maintains encapsulation stability while preventing dissolution. The hydrophobic nature of the coating ensures water repellency and prevents leaching.
Solution Approach 2:
The patent changes the hydrophobicity parameter of the coating to match the requirements for preventing water-soluble ingredient dissolution. By optimizing the hydrophobic character of the coating (through selection of polymeric MDI and crosslinking agents), the patent achieves stable encapsulation without ingredient dissolution.
5Reliability
If reverse phase encapsulation is used, then aqueous phase is inner phase, but active ingredients must be dissolved in water-immiscible solvent or molten solution
Solution Approach 1:
The patent uses a hydrophobic coating as an intermediary that eliminates the need for complex dissolution procedures. The coating provides a stable barrier that prevents water from reaching the active ingredient, thereby simplifying the manufacturing process. No dissolution in water-immiscible solvents or molten solutions is required.
Solution Approach 2:
The patent changes the approach from requiring dissolution in water-immiscible solvents to using a hydrophobic coating barrier. This parameter change in the coating's hydrophobicity allows the active ingredient to remain in its original form without requiring dissolution, thereby simplifying manufacturing.
6Reliability
If matrix encapsulation is used, then active ingredient particles are enclosed in solid form, but crushing process partially exposes previously protected particles
Solution Approach 1:
The patent uses a hydrophobic coating as an intermediary protective layer that remains intact during handling. This coating prevents the active ingredient particles from being exposed during crushing or mechanical treatment. The coating's adherence to the particle surface ensures protection is maintained throughout the manufacturing process.
Solution Approach 2:
The patent changes the protection mechanism from physical enclosure (matrix encapsulation) to chemical hydrophobic coating. This coating approach provides superior protection against exposure during mechanical processing, as the coating remains intact and adherent to the particle surface.
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 process achieves a significant reduction in water solubility and delayed release of the active ingredient, maintaining effectiveness and stability even under humid conditions, as demonstrated by the examples with acetamiprid coatings.
Implementation Method 1
adding a polymer former to the solution, optionally in a second organic solvent, whereby the viscosity of either the solution to be added or the solution obtained is optionally adjusted by adding a suitable auxiliary agent, and adding a crosslinking agent with at least two functional groups in a third organic solvent to the resulting solution, whereby the viscosity of either the solution to be added or the solution obtained is adjusted, if necessary, by adding a suitable auxiliary agent
Implementation Method 2
adding a crosslinking agent with at least two functional groups in a third organic solvent to the resulting solution, whereby the viscosity of either the solution to be added or the solution obtained is adjusted
Implementation Method 3
providing a coating, the coating at least reducing the water solubility of the coated particles in a defined manner, but above all delaying it until the desired effect of the active ingredient is achieved
Implementation Method 4
uniformly distributing the crystals of an active ingredient in a first organic solvent with the addition of a dispersing aid in an anhydrous process
Data Source
AI summary
The invention relates to a method for production of concentrates of water-soluble active agents, wherein, in a waterless method using solid active agents as starting materials, the crystals of an active agent are uniformly distributed in a first organic solvent to which a dispersing agent is added, the viscosity of the solution thus obtained is adjusted as applicable by a suitable auxiliary agent, a polymer creator is added to the solution thus obtained, in a second organic solvent as applicable, wherein the viscosity of either the solution to be added or the solution to be obtained is adjusted by the addition of a suitable auxiliary agent, and a crosslinking agent having at least two functional groups in a third organic solvent is given to the obtained solution, wherein the viscosity of either the added or obtained solution is in turn adjusted by the addition of a suitable auxiliary agent and the polymer creator is selected from the group comprising low-viscosity polymethylene-polyphenylisocyanate, preferably having an average NCO content of 25-35, particularly preferably 30-32%, and mixtures thereof.