Silicone Rubber Cable Insulation Low Smoke Release
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Solution Overview
Problem
Silicone polymers used in energy and telecommunications cables emit thick white smoke when burning, failing to meet safety standards for fire behavior and smoke release, and compromising mechanical and dielectric properties.
Innovation Solution
A crosslinkable silicone rubber composition is developed, using a combination of a crosslinkable silicone polymer, inorganic filler, platinum-based compound, and magnesium oxide, where the inorganic filler is less than 50% by mass and magnesium oxide is between 1-3% by mass, crosslinked using an organic peroxide, to create a polymer layer with improved ignition retardancy and reduced smoke release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicone polymer is used as insulating or protective layer material, then good mechanical and dielectric properties are achieved, but thick white smoke is emitted during combustion
Solution Approach 1:
The patent converts the harmful smoke-emitting combustion of silicone polymer into a beneficial low-smoke combustion process by adding magnesium oxide. The MgO catalyzes the decomposition of silicone polymer to produce silicon carbide and carbon instead of traditional smoke, transforming a harmful combustion characteristic into a beneficial one while maintaining the base material's mechanical and dielectric properties.
Solution Approach 2:
The patent changes the chemical composition parameters of the silicone polymer by incorporating specific amounts of magnesium oxide (0.1-5 wt%) and controlling inorganic filler content (≤50 wt%). This parameter modification alters the combustion behavior to reduce smoke release while preserving the mechanical and dielectric properties required for cable insulation and protection.
2Reliability
If inorganic filler is increased to improve fire resistance, then ignition delay properties are enhanced, but smoke release properties deteriorate
Solution Approach 1:
The patent optimizes the parameter balance by limiting inorganic filler to ≤50 wt% and adding magnesium oxide at 0.1-5 wt%. This specific parameter combination achieves both ignition delay (fire resistance) and low smoke release, resolving the contradiction between these two fire safety requirements that cannot be satisfied by inorganic filler alone.
Solution Approach 2:
The patent creates a composite material system combining silicone polymer, inorganic filler (≤50 wt%), and magnesium oxide (0.1-5 wt%). This composite approach allows the inorganic filler to provide ignition delay while magnesium oxide simultaneously controls smoke release, achieving both fire safety requirements through material composition rather than relying on inorganic filler alone.
3Object-generated harmful factors
If conventional flame retardant additives are added to reduce smoke, then smoke release is reduced, but mechanical and dielectric properties deteriorate
Solution Approach 1:
Instead of using conventional flame retardant additives that compromise mechanical and dielectric properties, the patent uses magnesium oxide to convert the combustion process itself into a low-smoke reaction. The MgO catalyzes decomposition to produce silicon carbide and carbon, achieving smoke reduction through beneficial combustion chemistry rather than harmful additives, thus preserving the polymer's mechanical and dielectric 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 composition significantly reduces smoke release during combustion, maintaining mechanical and dielectric properties while releasing at least half as much carbon dioxide fumes as comparative compositions, and demonstrates a synergistic effect with platinum and magnesium oxide.
Implementation Method 1
the use of a compound based on platinum and a judiciously chosen quantity of MgO presents a synergistic effect on the smoke release index in the event of combustion
Implementation Method 2
said crosslinked polymer layer being obtained from a silicone rubber composition resulting from the crosslinking, by an organic peroxide under the action of heat
Data Source
AI summary
The present invention relates to a power and/or telecommunication cable comprising at least one insulating layer and/or at least one outer protective sheath (or at least one layer playing the dual role of insulation and protective sheath), obtained from a crosslinkable silicone rubber composition comprising at least one crosslinkable silicone polymer, at least one inorganic filler, at least one platinum-based compound and magnesium oxide, and wherein the amount of inorganic filler is less than or equal to 50% by mass and the amount of magnesium oxide (MgO) varies from 1 to 3% by mass.