Self-Extinguishing Cable Coating for Drip-Free Flame Retardance
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Solution Overview
Problem
Current flame-retardant cables require high quantities of fillers like magnesium hydroxide and aluminium hydroxide to achieve effective flame retardation, leading to increased viscosity, decreased productivity, and impaired mechanical properties, while still allowing for the formation of flaming droplets during fires, which complicates certification and safety standards.
Innovation Solution
A low smoke zero halogen (LSOH) flame-retardant cable with a polymer composition comprising less than 170 phr of metal hydroxide, 1 to 10 phr of phyllosilicate clay, at least 1 phr and less than 10 phr of melamine or its derivatives, and an alkali or alkaline-earth metal carbonate, which prevents dripping and maintains mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high quantities of metal hydroxide fillers (170-200 phr) are used to achieve effective flame retardation and self-extinguishing properties, then the flame-retardant performance is improved, but the viscosity of the material increases considerably leading to decreased extrusion speeds and drop in productivity
Solution Approach 1:
The patent changes the concentration parameter of metal hydroxide fillers from the conventional high range (170-200 phr) to a reduced range (100-150 phr), while compensating with optimized amounts of other flame-retardant additives to maintain effective flame-retardant performance at lower filler quantities, thereby reducing viscosity and improving extrusion speed
Solution Approach 2:
The patent uses a composite flame-retardant system combining metal hydroxide fillers with specific amounts of flame-retardant additives (melamine derivatives, phosphorus compounds, nitrogen compounds) to achieve effective flame retardation with reduced filler content, avoiding the viscosity problems associated with high filler loads
2Reliability
If high quantities of flame-retardant fillers (170-200 phr) are used to achieve satisfactory flame propagation retarding properties, then the flame-retardant effectiveness is improved, but the mechanical properties of the resulting cable deteriorate substantially
Solution Approach 1:
The patent reduces the filler content parameter from 170-200 phr to 100-150 phr and optimizes the distribution and types of flame-retardant additives to maintain flame propagation resistance while preserving the mechanical integrity and flexibility of the cable insulation
Solution Approach 2:
The patent employs a composite formulation combining metal hydroxide fillers with flame-retardant additives (melamine derivatives, phosphorus compounds) that provide flame propagation resistance without the excessive filler loading that would compromise mechanical properties
3Reliability
If great amounts of flame-retardant filler are used to prevent formation of flaming droplets during fire, then the self-extinguishing properties are improved, but the mechanical features of the cable are impaired, manufacturing cost increases and manufacturing difficulty increases
Solution Approach 1:
The patent optimizes the filler content parameter to 100-150 phr (reduced from conventional 170-200 phr) and adjusts the types and amounts of flame-retardant additives to achieve self-extinguishing properties and prevent flaming droplet formation without requiring excessive filler that would complicate manufacturing
Solution Approach 2:
The patent uses a composite flame-retardant system with metal hydroxide fillers combined with flame-retardant additives (melamine derivatives, phosphorus compounds, nitrogen compounds) that achieves self-extinguishing performance and prevents droplet formation at manageable filler levels, maintaining ease of manufacturing
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 solution effectively prevents flaming droplets during fires, meets stringent certification standards, and ensures good workability and mechanical properties, particularly in extrusion processes, without the need for excessive filler amounts.
Implementation Method 1
a cable, either electric or optical or hybrid, exhibits improved flame-retardant and self-extinguishing properties, particularly a substantially null dripping under fire, when it is provided with a coating layer made of a polymer composition comprising at least one metal hydroxide as flame-retardant filler and a specific combination of flame-retardant aids in specific amount ranges
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 (e.g. polyethylene and/or polyethylene copolymers, optionally cross-linked) filled with inorganic hydroxide fillers, such as magnesium hydroxide and/or aluminium hydroxide, which confer flame-retardant properties to a cable coating layer
Data Source
AI summary
A flame-retardant cable having a core is disclosed. The cable contains at least one conductor and a coating made from a low smoke zero halogen flame-retardant polymer composition. The polymer composition contains a halogen free base polymer added with a) less than 170 phr of at least one metal hydroxide; b) from 1 to 10 phr of a phyllosilicate clay; c) at least 1 phr and less than 10 phr of melamine or a derivative thereof; and d) an alkali or alkaline-earth metal carbonate. The cable has improved reaction to fire performances especially in that no dripping occurs during burning, which renders it compliant with the requirements of the more recent international standards.