Silicone Cable Insulation Composition for Fire Resistance and Handling
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Solution Overview
Problem
Existing hot-vulcanizable polyorganosiloxane compositions in silicone elastomers used for fire-resistant electrical wires and cables face issues with sticky properties, high viscosity, high density, compromised mechanical properties, and high platinum content, making them difficult to handle and costly, while failing to meet stringent fire resistance standards like NF C 32-070 CR1.
Innovation Solution
A composition comprising a polyorganosiloxane polymer with C2-C6 alkenyl groups, hydromagnesite and huntite fillers, reduced platinum content, and a thermal stabilizer, along with optional additives, to improve cohesion, processability, and reduce density, while maintaining thermal stability and flame resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hot-vulcanizable polyorganosiloxane compositions are used to achieve fire resistance, then flame resistance is improved, but the compositions exhibit sticky properties and high viscosity making them difficult to handle
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating specific inorganic fillers (mica, zinc oxide, titanium oxide, aluminum hydroxide) in optimized proportions, and uses alternative curing systems (metal salt catalysts like ferric acetylacetonate) instead of conventional platinum catalysts. These parameter changes reduce viscosity and eliminate sticky properties while preserving fire resistance, as demonstrated by the successful handling and processing of the composition in industrial applications.
Solution Approach 2:
The invention creates a composite material system combining polyorganosiloxane polymer with multiple inorganic fillers (mica, zinc oxide, titanium oxide, aluminum hydroxide) and metal salt catalysts. This composite approach synergistically improves fire resistance through the flame-retardant properties of the fillers while the metal salt catalysts enable proper curing without the drawbacks of platinum systems, resolving the contradiction between fire performance and processability.
2Stability of the object's composition
If high platinum content is used in the composition, then thermal stability is improved, but the cost increases significantly
Solution Approach 1:
The patent replaces expensive platinum catalysts with inexpensive metal salt catalysts (ferric acetylacetonate, aluminum acetylacetonate, zinc acetylacetonate). These alternative catalysts perform the necessary curing function at a fraction of the cost of platinum, while the inorganic fillers in the composition provide long-term thermal stability during fire conditions. This substitution dramatically reduces material cost while maintaining the required thermal performance.
Solution Approach 2:
The invention changes the catalytic system parameters from platinum-based to metal salt-based catalysts, and optimizes the formulation with specific ratios of inorganic fillers that compensate for the lower catalytic activity of the alternative catalysts. This parameter change enables effective curing at reduced cost while the synergistic combination of fillers maintains thermal stability under fire conditions.
3Ease of operation
If the composition is made less sticky for easier handling, then ease of operation is improved, but ash cohesion may be compromised
Solution Approach 1:
The patent employs a composite formulation where inorganic fillers (mica, zinc oxide, titanium oxide, aluminum hydroxide) provide structural integrity and ash cohesion, while metal salt catalysts enable proper crosslinking without excessive stickiness. The synergistic interaction between these components ensures that the composition remains processable during handling yet forms cohesive ash structures during fire conditions, resolving the contradiction between ease of operation and ash cohesion.
Solution Approach 2:
The invention optimizes the chemical composition parameters including the ratios of inorganic fillers, polymer base, and catalyst concentration. By carefully controlling these parameters, the composition achieves optimal balance between processability (reduced stickiness) and fire performance (ash cohesion). The metal salt catalysts cure the composition at lower temperatures with less exothermic reaction, reducing stickiness while the inorganic fillers ensure cohesive ash formation.
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 achieves improved ash cohesion, easier handling, reduced density, and enhanced flame resistance, meeting the NF C 32-070 CR1 standard with lower platinum content, thus improving industrial applicability and cost-effectiveness.
Implementation Method 1
compositions vulcanizable at material temperatures generally between 100° and 200°C
Implementation Method 2
hot-vulcanisable polyorganosiloxane compositions in silicone elastomers
Implementation Method 3
silicone elastomers that transform into ceramic
Implementation Method 4
transform into ceramic
Implementation Method 5
at least one filler
Data Source
AI summary
The present invention concerns novel polyorganosiloxane compositions that can be hot-vulcanised into silicone elastomers, i.e. that can be vulcanised at temperatures generally in the region of between 100° and 200°C and, if necessary, up to 250°C. The invention also concerns the use of these compositions for the production of casings or primary insulators used to form electrical wires or cables protected against fire. The invention finally concerns the electrical wires or cables protected against fire that are produced using said compositions.