Silane-Crosslinked Microcapsules for High-Temperature Core Retention
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Solution Overview
Problem
Existing microcapsules fail to retain hydrophobic core materials under high temperatures and pressures, particularly during the spinning of fibers, and often rely on formaldehyde condensation products that have drawbacks such as reduced impermeability and potential for formaldehyde release.
Innovation Solution
Microcapsules with a polymeric shell formed from 1-20% polymerizable silane compound, 1-94% hydrophobic mono-functional ethylenically unsaturated monomer, and 5-98% poly-functional ethylenically unsaturated monomer, incorporating a hydrophilic polymer covalently bonded to the shell for enhanced strength and impermeability, which improves retention of the core material under harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If melamine formaldehyde resin shell is used to encapsulate hydrophobic liquid, then the shell is impervious and durable, but it becomes less impermeable at elevated temperatures and may release formaldehyde
Solution Approach 1:
The patent changes the chemical composition parameters of the shell by using polyfunctional ethylenically unsaturated monomers (divinyl benzene, ethoxylated bisphenol A diacrylate, propoxylated neopentyl glycol diacrylate, tris 2-hydroxyethyl) isocyanurate triacrylate, and alkane diol diacrylate) instead of melamine formaldehyde resin. This chemical parameter change enables the shell to maintain its impermeability and structural integrity at elevated temperatures up to 150°C or higher, while avoiding formaldehyde release issues.
2Reliability
If conventional polymeric shells are used for microcapsules, then they provide basic encapsulation, but they cannot withstand high temperatures and pressures during fiber spinning
Solution Approach 1:
The patent creates a composite shell structure by combining polyfunctional ethylenically unsaturated monomers with specific cross-linking agents and optional additives like silane compounds and metal salts. This composite material approach produces a shell with enhanced thermal resistance and mechanical strength that can withstand fiber spinning conditions (temperatures up to 150-350°C and high pressures) while reliably retaining the hydrophobic core material.
3Loss of substance
If the shell is made impermeable to retain core material, then core retention is improved, but the shell may not withstand high pressures during processing
Solution Approach 1:
The patent applies local quality by creating a shell with non-uniform cross-linking density and composition. The shell contains polyfunctional ethylenically unsaturated monomers with different functional groups that create regions of varying density and flexibility. This local variation in shell properties allows the structure to be sufficiently impermeable to prevent core material loss while having enough flexibility and strength distribution to withstand high processing pressures without catastrophic failure.
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 retention of the core material under elevated temperatures and high pressures, maintaining integrity during fiber spinning and other harsh treatments without using formaldehyde condensation products, ensuring durability and stability.
Implementation Method 1
The shell is formed from hydrophobic mono functional ethylenically unsaturated monomer, polyfunctional ethylenically unsaturated monomer
Implementation Method 2
1 to 20% by weight of polymerisable silane compound
Implementation Method 3
polymerisable silane compound
Implementation Method 4
incorporating a hydrophilic polymer covalently bonded to the shell
Data Source
AI summary
A microcapsule comprising a core containing a hydrophobic liquid or wax and a polymeric shell formed from: i) 1 to 20% by weight of polymerizable silane compound, ii) 1 to 94% by weight of hydrophobic mono functional ethylenically unsaturated monomer, iii) 5 to 98% by weight of polyfunctional ethylenically unsaturated monomer, and iv) 0 to 60% by weight of other mono functional monomer(s), wherein components (i), (ii), (iii) and (iv) total 100%, and in which the microcapsule also includes a hydrophilic polymer which is covalently bonded to the microcapsule. The invention includes a process for the manufacture of particles and the use of particles in articles, such as fabrics, and coating compositions, especially for textiles.