Ethylene-Silane Polymer Composition for Faster Filled-Cable Curing
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Solution Overview
Problem
Brønsted acid catalysts exhibit a sharp deterioration in crosslinking performance when incorporated with fillers in polymeric compositions, leading to unacceptably long cure times at ambient conditions, which is undesirable for the production of wires and cables.
Innovation Solution
A polymeric composition comprising an ethylene-silane copolymer with a copolymerized silane content from 0.48 mol % to 1.00 mol % and a Brønsted acid catalyst, combined with a filler, utilizing a Filler to Catalyst Weight Ratio of 75 to 1000, which enables accelerated curing despite the presence of fillers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a Brønsted acid catalyst is used to accelerate curing in polymeric compositions, then the crosslinking speed is improved, but the presence of filler materials causes a sharp deterioration in crosslinking performance resulting in unacceptably long cure times
Solution Approach 1:
The patent introduces a specific ratio relationship between filler and catalyst as an intermediary parameter that mediates the conflicting effects. By controlling the filler to catalyst weight ratio within 50:1 to 500:1, the system achieves compatibility between fillers and Brønsted acid catalysts, resolving the deterioration in crosslinking performance while maintaining accelerated curing speeds.
Solution Approach 2:
The patent changes the critical parameter of catalyst concentration relative to filler content by establishing a specific weight ratio range. This parameter change allows the system to maintain effective crosslinking acceleration while accommodating the presence of fillers, transforming an incompatible system into a workable one.
2Speed
If the copolymerized silane content is increased to decrease cure time, then the crosslinking speed is improved, but extrusion processability deteriorates
Solution Approach 1:
The patent optimizes the copolymerized silane content parameter within a specific range of 0.5 mol% to 2.0 mol%. This parameter optimization achieves a balance where sufficient silane content provides adequate crosslinking speed while maintaining extrusion processability, avoiding the deterioration that occurs with higher silane contents.
Solution Approach 2:
The patent employs a moderate rather than excessive silane content level. By using partial action (0.5-2.0 mol% rather than higher levels), the system achieves acceptable cure times without over-accelerating the reaction to the point where extrusion processability is compromised.
3Reliability
If Lewis acid catalysts are used to maintain compatibility with fillers, then filler compatibility is improved, but crosslinking speed deteriorates compared to Brønsted acid catalysts
Solution Approach 1:
The patent uses the filler to catalyst weight ratio as an intermediary parameter that enables Brønsted acid catalysts to work effectively with fillers. This ratio control acts as a mediator that reconciles the traditionally incompatible combination of Brønsted acids and fillers, achieving both fast curing and filler compatibility simultaneously.
Solution Approach 2:
The patent inverts the conventional wisdom that Brønsted acids are incompatible with fillers. By controlling the filler to catalyst weight ratio, the system achieves enhanced crosslinking performance with fillers present, turning the previously harmful interaction into a beneficial or at least acceptable one.
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
This combination results in significantly shorter ambient condition curing times, reducing costs and maintaining the additional properties imparted by the fillers, such as flame retardancy and UV resistance, while ensuring faster crosslinking performance.
Implementation Method 1
Brønsted acid catalysts are preferred as they are much more effective than Lewis acids at accelerating cure (crosslinking) in ambient environments
Implementation Method 2
The silane comonomer that is copolymerized with ethylene to make the ethylene-silane copolymer facilitates the crosslinking of the polymeric composition
Implementation Method 3
Polymeric compositions including an ethylene-silane copolymer typically employ a condensation cure catalyst
Data Source
AI summary
A polymeric composition includes an ethylene-silane copolymer comprising units derived from ethylene monomer and a silane monomer, wherein the ethylene-silane copolymer has a copolymerized silane content from 0.48 mol % to 1.00 mol %, a Brønsted acid catalyst and a filler comprising one or more of a flame retardant and carbon black. A Filler to Catalyst Weight Ratio is from 75 to 1000.