Flame-Retardant Air-Jetted Micro-Cable Outer Sheath
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Solution Overview
Problem
Current flame retardant air-blown microcables face challenges in achieving both good mechanical performance and effective flame retardancy, particularly in maintaining mechanical integrity with thin jackets while ensuring low smoke generation and acid value during fires, which is crucial for optical cables in densely packed networks.
Innovation Solution
The development of a flame retardant air-blown microcable utilizing an outer sheath composed of inorganic metal hydroxides, such as aluminum or magnesium hydroxide, combined with specific polymer components like ethylene-vinyl acetate copolymer and linear low-density polyethylene, along with a synergistic flame retardant like ammonium polyphosphate, to achieve a thin, high-performance, low-smoke, and halogen-free material that ensures excellent mechanical and flame retardant properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the molding thickness is increased to ensure flame retardant effect, then the flame retardant performance is improved, but the mechanical performance cannot be ensured
Solution Approach 1:
The patent changes the chemical composition parameters of the outer sheath material by incorporating specific flame retardant additives (metal hydroxides, nitrogen-containing compounds) and optimizing the polymer blend ratios. This allows achieving effective flame retardancy through chemical composition rather than increasing thickness, thus maintaining mechanical performance while improving fire safety
Solution Approach 2:
The patent creates a composite material system by combining multiple polymers (polyethylene, polypropylene, EVA) with flame retardant additives (metal hydroxides, ammonium polyphosphate) and coupling agents. This composite approach provides both the required mechanical strength and effective flame retardant properties within an optimized thickness range of 0.7-1.3mm
2Volume of moving object
If the molding thickness is decreased to achieve small thickness requirement, then the thickness requirement is met, but the flame retardant effect becomes poor
Solution Approach 1:
The patent optimizes the concentration and type of flame retardant additives in the composition. By using synergistic combinations (metal hydroxides with nitrogen-containing compounds) and optimizing their content ratios, the material achieves high flame retardant efficiency at reduced thickness, meeting both the thin-profile requirement and fire safety standards
Solution Approach 2:
The patent enhances the flame retardant properties locally within the polymer matrix by distributing flame retardant additives and coupling agents throughout the material. This creates zones of enhanced fire resistance throughout the outer sheath, achieving effective protection even at reduced overall thickness
3Reliability
If conventional flame retardant materials are used, then the flame retardant effect is improved, but the smoke quantity and heat release increase
Solution Approach 1:
The patent employs metal hydroxides (aluminum hydroxide, magnesium hydroxide) as flame retardants. These compounds decompose endothermically when exposed to fire, absorbing heat and releasing water vapor instead of promoting combustion. This converts what could be harmful thermal energy into a cooling effect, reducing both smoke generation and heat release while maintaining flame retardancy
Solution Approach 2:
The decomposition of metal hydroxides releases water vapor and creates a diluting effect that displaces oxygen and reduces the concentration of flammable gases and smoke particles. This creates a locally inert atmosphere around the burning material, suppressing combustion and reducing harmful smoke and heat release
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 solution provides optical cables with enhanced mechanical performance, low smoke generation, and reduced acid value during fires, meeting category C bunched combustion requirements and maintaining high light transmittance, while also improving air-blowing efficiency and reducing production and maintenance costs.
Implementation Method 1
the flame retardant is inorganic metal hydroxide; for example, the flame retardant is one or more selected from the group consisting of aluminum sodium hydroxide and aluminum hydroxide; in one or more embodiments, the flame retardant is inorganic magnesium hydroxide
Implementation Method 2
an outer sheath (6) is clad on an outer surface of the stranded loose tube, wherein the outer sheath (6) is further filled therein with a cable paste (7)
Data Source
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AI summary
A flame retardant air-blown microcable, comprising a central reinforcement member (1), wherein a loose tube (2) is stranded on an outer surface of the central reinforcement member (1), an optical fiber unit (4) and a first water blocking substance are provided in the loose tube (2), wherein the optical fiber unit (4) is an optical fiber bundle, the first water blocking substance is a water-blocking fiber paste, an outer sheath (6) is clad on an outer surface of the stranded loose tube (2), and the outer sheath (6) is further filled therein with a cable paste (7). The outer sheath (6) comprises following components: 50-60 parts of ethylene-vinyl acetate copolymer EVA, linear low-density polyethylene LLDPE, flame retardant, synergistic flame retardant, plasticizer, lubricant, coupling agent, compatilizer, antioxidant, carbon black, and amide slipping agent. It has a small preparation thickness, effectively ensuring the mechanical performances, and has good flame-retardant performance, ensuring excellent performances of the optical cable such as meeting requirement of category C bunched combustion, high light transmittance, and a low acid value.