Organo Onium Curative for Transparent Fluoroelastomers
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Solution Overview
Problem
Fluoroelastomers face challenges with undesirable metal residues from organotin catalysts and lack of rheology control in cure systems, and most are cured into colored or opaque materials with high compression set, especially at high temperatures.
Innovation Solution
A curative composition comprising a cation and an anion of specific formulas, which form triazine crosslinks in perfluoroelastomers, providing improved rheology control and clear, transparent fluoropolymer articles with low compression set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If organotin catalysts are used for curing fluoroelastomers, then curing efficiency is improved, but undesirable metal residues are left in the cured product
Solution Approach 1:
The patent removes the harmful organotin catalyst from the curing system and replaces it with an organo onium salt curative. This extraction of the harmful element (metal catalyst) eliminates metal residues while maintaining curing functionality through an alternative chemical mechanism involving triazine crosslink formation.
Solution Approach 2:
The patent employs ammonia-generating compounds as a temporary curative system that decomposes during curing to release ammonia, which then facilitates triazine crosslink formation. The curative itself is consumed in the process, leaving no persistent harmful residues, unlike organotin catalysts that remain as metal contaminants.
2Ease of manufacture
If conventional cure systems are used in fluoroelastomers, then curing is achieved, but rheology control during processing is insufficient
Solution Approach 1:
The patent modifies the chemical parameters of the curative system by using organo onium salts with specific structures (Formula I) and controlling the nitrogen-containing cure site monomer content (0.1-5 mol%). These parameter changes enable precise rheology control during processing while maintaining effective curing, addressing both manufacturability and processability.
3Strength
If most known fluoroelastomers are cured, then crosslinking is achieved, but the cured materials become colored or opaque
Solution Approach 1:
The patent uses ammonia-generating compounds as a temporary curative that decomposes during curing to release ammonia gas. This transient curative mechanism enables crosslinking without leaving colored byproducts, as the ammonia escapes and the final cured product contains only the transparent triazine crosslinked network.
Solution Approach 2:
The patent creates an inert curing environment by using organo onium salts that do not introduce colored contaminants during the curing process. The curative system operates in a chemically inert manner that prevents discoloration, maintaining the optical clarity of the fluoroelastomer while achieving effective crosslinking.
4Temperature
If fluoroelastomers are cured to achieve crosslinking, then thermal resistance is improved, but compression set increases at high temperatures
Solution Approach 1:
The patent optimizes the composition parameters by incorporating nitrogen-containing cure site monomers at controlled levels (0.1-5 mol%) and using specific organo onium salt structures. These parameter changes create a crosslinked network with optimal density and distribution, achieving high thermal resistance while maintaining low compression set through improved network uniformity.
Solution Approach 2:
The patent creates a composite crosslinked structure by combining the fluoroelastomer matrix with triazine crosslinks formed through the organo onium salt curative system. This composite network structure integrates the base polymer with the crosslinked framework, achieving both high-temperature stability and low compression set through synergistic material properties.
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 curative composition effectively generates triazine crosslinks in perfluoroelastomers, offering superior high-temperature performance, transparency, and reduced compression set, making them suitable for harsh chemical and high-temperature applications.
Implementation Method 1
generates triazine crosslinks in perfluoroelastomers
Data Source
AI summary
A curative composition comprising a cation and an anion of the formula Anq−Qpm+, wherein m, n, p, and q are positive integers, wherein m*p=n*q, wherein Qm+ is an organo onium, and Aq− is an anion, provided that at least one Aq− is selected from the formula:wherein each R independently is H, halo, alkyl, aryl, aralkyl, or cycloalkyl, and which also may be halogenated, fluorinated, or perfluorinated, wherein two or more of R and R′ groups may together form a ring, wherein each R group independently may contain one or more heteroatom(s), wherein R′ can be the same as R, with the proviso that R′ cannot be halo. Also provided are a fluoropolymer composition including this curative, a method of making a fluoropolymer, and fluoropolymer articles containing curable or cured fluoropolymer compositions.