Optical Fiber Cable Dual-Layer Sheath Flame Retardance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing optical fiber cables struggle to balance flame retardance with sufficient strength, as materials with high flame retardance typically have low Young's modulus and reduced strength.

Innovation Solution

The optical fiber cable features a dual-layer sheath structure, where the outer layer is made of a material with a density of 1.4 g/cm3 or more and an oxygen index of 36 or more for high flame retardance, while the inner layer has a density less than 1.4 g/cm3 for maintaining cable strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a material with high flame retardance is used for the sheath, then flame retardance is improved, but strength decreases

Engineering Contradiction:

Improveflame retardanceVSAvoidsheath strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The sheath is divided into two distinct layers: an inner layer and an outer layer. The inner layer (density < 1.4 g/cm³) provides structural strength and flexibility, while the outer layer (density ≥ 1.4 g/cm³, oxygen index ≥ 36) provides flame retardance. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between strength and flame retardance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sheath uses a composite structure combining two materials with different density characteristics. The inner layer uses a material with lower density for strength, while the outer layer uses a material with higher density and higher oxygen index for flame retardance. This composite approach enables simultaneous achievement of both strength and flame retardance properties.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If the density of the sheath material is increased to improve flame retardance, then flame retardance is improved, but cable flexibility and ease of installation deteriorate

Engineering Contradiction:

Improveflame retardanceVSAvoidcable flexibility

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The sheath is segmented into an inner layer with lower density (maintaining flexibility) and an outer layer with higher density (providing flame retardance). The inner layer's lower density material ensures the cable remains flexible and easy to install, while the outer layer's higher density material provides the required flame retardance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the sheath have different density characteristics tailored to their specific functions. The inner layer has lower density for flexibility and handling, while the outer layer has higher density for flame retardance. This local differentiation of material properties resolves the contradiction between flexibility and flame retardance.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250147253A1Optical fiber cable

Publication Date: 2025.05.08 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

An optical fiber cable includes: a plurality of optical fibers; and a sheath provided around the plurality of optical fibers. The sheath includes an inner layer provided outside the plurality of optical fibers, and an outer layer provided outside the inner layer. A density of a material used for the outer layer is 1.4 g/cm3 or more, and a density of a material used for the inner layer is less than 1.4 g/cm3. An oxygen index of the material used for the outer layer is 36 or more.