Dual-Layer Jacketing for Plastic Optical Fiber Flame Retardance
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Solution Overview
Problem
Existing plastic optical fiber (POF) cables face challenges in achieving high flame retardance without compromising processability, as methods involving inorganic flame retardants require high concentrations, leading to surface roughness and reduced resin strength, and fluorine-based resins can cause melt fracture and adhesion issues, making it difficult to strip the jacketing layer.
Innovation Solution
A POF cable design featuring a dual-layer jacketing system, where the inner layer consists of a copolymer of olefin and a (meth)acrylic compound and the outer layer is a fluorine-based resin with 50% or more fluorine content, allowing for easy stripping and maintaining high flame retardance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic flame retardants are used to achieve high flame retardance, then flame retardance is improved, but surface roughness increases and resin strength decreases
Solution Approach 1:
The patent introduces a specific resin composition as an intermediary layer between the POF and the outer sheath. This intermediate resin layer (containing 20-80 mass% of a specific polymer) acts as a mediator that provides flame retardance without the surface roughness and strength reduction problems caused by inorganic flame retardants. The intermediary layer transfers the flame retardant function while maintaining surface quality and mechanical strength.
2Reliability
If fluorine-based resin is used as outer sheath to improve flame retardance, then flame retardance is improved, but melt fracture occurs causing surface roughness
Solution Approach 1:
The patent employs a composite material structure where the outer sheath consists of fluorine-based resin combined with specific additives and modifiers. This composite formulation (containing fluorine-based resin with specific glass transition temperature and molecular weight, along with 3-20 mass% of specific polymer) maintains the excellent flame retardance of fluorine-based resin while suppressing melt fracture and surface roughness through the synergistic effect of the composite components.
3Reliability
If fluorine-based resin is used as outer sheath to improve flame retardance, then flame retardance is improved, but adhesion to POF increases making stripping difficult
Solution Approach 1:
The patent segments the sheath structure into distinct functional layers: an inner resin layer with specific adhesion properties and an outer fluorine-based resin layer with flame retardance properties. This segmentation allows the inner layer to provide controlled adhesion for easy stripping while the outer layer delivers high flame retardance, resolving the contradiction between these two requirements.
4Manufacturing precision
If covering speed is reduced or molding temperature is raised to prevent melt fracture in fluorine-based resin, then surface roughness is reduced, but optical properties of POF are deteriorated
Solution Approach 1:
The patent optimizes specific parameters of the resin composition, including glass transition temperature (Tg: -50°C to 0°C) and molecular weight (50,000 to 200,000), along with the addition of specific polymers (20-80 mass%). These parameter changes enable the resin to maintain low viscosity and good flow characteristics at normal processing conditions, preventing melt fracture and surface roughness without requiring temperature increases that would damage POF optical properties.
Data Source
AI summary
Provided is a plastic optical fiber cable including a plastic optical fiber 12 comprising of a core 11A and a cladding 11B, and a jacketing layer covering the plastic optical fiber 12, in which the jacketing layer includes at least two layers of an inner layer 13 and an outer layer 14, the inner layer 13 is formed of a resin comprising of a copolymer of ethylene and a (meth)acrylic compound, and the outer layer 14 is formed of a fluorine-based resin. A plastic optical fiber cable excellent in flame retardance, appearance, and processability at the time of use is obtained from the plastic optical fiber cable described above.