LSOH Cable Outer Layer to Prevent Fire Dripping
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Solution Overview
Problem
Existing flame-retardant electrical cables face challenges in achieving reduced dripping when exposed to high temperatures, while maintaining good mechanical properties and workability, especially in extrusion processes.
Innovation Solution
The use of a modified montmorillonite with micrometric particle dimensions in the outermost layer of the cable, combined with a low smoke zero halogen (LSOH) flame-retardant polymer composition, enhances flame-retardant properties and resistance to dripping without compromising mechanical properties or workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substantial amounts of inorganic filler are introduced to obtain satisfactory flame retarding effect, then flame retardancy is improved, but mechanical properties and workability are significantly worsened
Solution Approach 1:
The patent changes the particle size parameter of the inorganic filler from conventional large particles to micrometric particles (1-10 μm), and optimizes the filler content to 30-70 parts per 100 parts of polymer. This parameter optimization achieves satisfactory flame retardancy while maintaining good mechanical properties and extrusion workability, resolving the contradiction between flame safety and manufacturing ease
Solution Approach 2:
The patent uses a composite filler system combining micrometric inorganic hydroxide particles with a polyolefin matrix, creating a optimized composite material that balances flame retardant performance with mechanical integrity and processability, avoiding the need for excessive filler loading
2Reliability
If substantial amounts of inorganic filler are introduced to obtain satisfactory flame retarding effect, then flame retardancy is improved, but mechanical properties are significantly worsened
Solution Approach 1:
The patent optimizes the particle size parameter of inorganic filler to micrometric range (1-10 μm), which provides sufficient flame retardant effect at lower filler concentrations (30-70 parts per 100 parts polymer), thereby preserving the mechanical strength and flexibility of the cable insulation while achieving required fire safety performance
3Reliability
If flame-retardant fillers are added to enhance effectiveness against flame progression, then flame retardancy is improved, but dripping containment is barely impacted
Solution Approach 1:
The patent optimizes the particle size parameter of inorganic filler to micrometric range (1-10 μm), which provides sufficient flame retardant effect at lower filler concentrations (30-70 parts per 100 parts polymer), thereby preserving the mechanical strength and flexibility of the cable insulation while achieving required fire safety performance
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 proposed solution significantly reduces or eliminates dripping during fires, improves flame-retardant performance, and maintains good mechanical properties and workability, making it suitable for low-voltage applications and compliance with stringent international standards.
Implementation Method 1
The present disclosure relates to a flame-retardant electric cable having a core comprising at least one electric conductor, an electrically insulating coating, and an outermost layer made from a substantially thermoplastic, low smoke zero halogen (LSOH) flame-retardant polymer composition filled with inorganic fillers, in particular filled with magnesium hydroxide and/or aluminium hydroxide and/or calcium carbonate and/or titanium dioxide and/or barium sulphate and/or silica and/or modified montmorillonite having micrometric particle dimensions
Implementation Method 2
the production of flame-retardant cables is currently directed towards the use of halogen-free and low-smoke materials (LSOH) using polyolefin-based compositions for the insulating layer (e.g. polyethylene and/or polyethylene copolymers, optionally cross-linked) filled with inorganic hydroxides fillers, such as magnesium hydroxide and/or aluminium hydroxide, which confer flame-retardant properties to the insulating layer
Data Source
Figure 1~2
AI summary
A flame-retardant electric cable (10;20) having a core comprising at least one electric conductor (11), an electrically insulating coating (12) and an outermost layer (13a;14) made from a substantially thermoplastic, low smoke zero halogen flame-retardant polymer composition comprising: a) a polymeric base made of at least one polyethylene homopolymer or copolymer having a density of 0.94 g/cm3 at most; b) 60-64% by weight of a metal hydroxide; c) at least 2% by weight of an ammonium coated montmorillonite having average particle dimensions of from 5 to 20 µm; and d) a polysiloxane. Such a cable has improved reaction to fire performances, especially reduced dripping or absence of dripping during burning, which render it compliant with the requirements of the more recent international standards.