Solvent Resistant Microcapsules via Polyisocyanate Interfacial Polymerization
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Solution Overview
Problem
Capsules used in laser markable compositions often have limited temperature and solvent resistance, leading to unwanted color formation and restricted application in laminated materials, as they can rupture under minor solvent exposure or high lamination temperatures.
Innovation Solution
The development of microcapsules with improved solvent and heat resistance is achieved through interfacial polymerization using a polyisocyanate and a compound containing reactive hydrogen, forming a robust polymer shell, specifically utilizing polyisocyanate derivatives like isocyanurate and polyamines, and optimizing the preparation process with elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capsules are used in laser markable compositions, then encapsulation function is achieved, but solvent resistance is poor leading to capsule rupture
Solution Approach 1:
The patent changes the chemical composition parameters of the capsule shell by using polyisocyanate derivatives (isocyanurate-based) instead of conventional isocyanate polymers. This chemical parameter change results in a shell with superior solvent resistance that prevents capsule rupture while maintaining the encapsulation function for leuco dyes and developing agents.
Solution Approach 2:
The patent employs composite material structure by combining polyisocyanate derivative with specific multifunctional amines to create a hybrid polymer shell. This composite approach produces a capsule shell that integrates the high solvent resistance of polyisocyanurate with the functional properties needed for laser marking applications.
2Reliability
If capsules are used in laser markable compositions, then encapsulation function is achieved, but temperature resistance is poor leading to capsule rupture at high lamination temperatures
Solution Approach 1:
The patent changes the thermal stability parameters of the capsule shell by selecting polyisocyanate derivatives with higher thermal resistance characteristics. This parameter change enables the capsule shell to withstand high lamination temperatures without rupturing, while still allowing controlled rupture during laser marking to release the encapsulated compounds.
Solution Approach 2:
The patent designs a capsule shell that is intentionally made to be temperature-sensitive within a controlled range - stable during storage and handling but capable of controlled rupture during laser marking. The polyisocyanate derivative provides this controlled behavior, remaining intact during lamination but rupturing when exposed to laser energy.
3Adaptability or versatility
If conventional capsule shells are used, then ease of manufacture is maintained, but solvent and heat resistance are limited restricting applications
Solution Approach 1:
The patent modifies the polymerization parameters and material selection to use polyisocyanate derivatives that can be incorporated into existing capsule formation processes. By adjusting the chemical parameters of the shell material rather than changing the fundamental manufacturing approach, the patent maintains ease of manufacture while significantly improving solvent and heat resistance for expanded applications.
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 enhanced solvent resistance and mechanical strength, preventing unwanted color formation and allowing for higher lamination temperatures without capsule rupture, thus expanding their application in laser markable compositions and materials.
Implementation Method 1
The development of microcapsules with improved solvent and heat resistance is achieved through interfacial polymerization using a polyisocyanate and a compound containing reactive hydrogen, forming a robust polymer shell
Implementation Method 2
Upon infrared laser exposure, a rupture of the capsules may result in a reaction between the leuco dyes and the developing agents, which then triggers colour formation
Data Source
AI summary
A composition comprising a capsules having an improved solvent and heat resistance. The capsules are prepared via interfacial polymerization between a polyisocyanate comprising at least 1 substituted or unsubstituted arylene or heterearyl group and a compound including an active hydrogen. Such capsules comprising a leuco dye may be used in laser markable compositions.