Multimodal Cable Jacket Composition for Low Shrinkage and High ESCR
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Solution Overview
Problem
Current cable jacket compositions for high-density fiber optic cables face challenges in achieving low shrinkage, high environmental stress cracking resistance (ESCR), and improved processability while maintaining mechanical strength and hardness, with existing solutions often compromising on these properties.
Innovation Solution
A multimodal olefin copolymer composition with a density of 0.935-0.960 g/cm³ and a melt flow rate (MFR) of 2.2-10.0 g/10 min, combined with a MgCl₂-supported catalyst process involving two main polymerization stages, is used to create a cable jacket with ESCR of at least 2000 hours and shrinkage of 0.70% or lower, incorporating a bimodal polymer mixture of low and high molecular weight ethylene homopolymers or copolymers with 1-butene as a comonomer, and optionally including conductive fillers like carbon black.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cable jacket compositions are used, then mechanical strength and hardness are maintained, but shrinkage is high and environmental stress cracking resistance is poor
Solution Approach 1:
The patent uses a composite polymer composition consisting of at least two different polyethylene resins with distinct density and molecular weight characteristics. This composite approach combines the high ESCR of higher density polyethylene with the low shrinkage properties of lower density polyethylene, achieving both improved reliability and manufacturing precision simultaneously
Solution Approach 2:
The patent systematically varies key parameters including density (0.915-0.955 g/cm³ range), molecular weight distribution (bimodal with specific MFR ranges), and compositional ratios of different polyethylene resins. By optimizing these parameters, the composition achieves the dual goal of high ESCR and low shrinkage without compromising mechanical properties
2Manufacturing precision
If high density polyethylene is used to reduce shrinkage, then shrinkage decreases, but environmental stress cracking resistance deteriorates
Solution Approach 1:
The patent creates a balanced composite system where lower density polyethylene (providing low shrinkage) and higher density polyethylene (providing high ESCR) are combined in specific ratios. This composite material approach allows the final composition to exhibit both low shrinkage and high environmental stress cracking resistance simultaneously, overcoming the limitations of using either resin alone
3Ease of manufacture
If multimodal polymer mixture is used to improve processability, then processability enhances, but mechanical strength may be compromised
Solution Approach 1:
The patent optimizes the molecular weight distribution by incorporating a bimodal structure with specific MFR ranges (0.5-5.0 g/10min for higher density component, 5.0-20.0 g/10min for lower density component). This parameter optimization ensures the polymer has appropriate flow characteristics for excellent processability while maintaining sufficient mechanical strength through the higher molecular weight fraction
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 achieves superior properties in terms of shrinkage, ESCR, and processability, reducing cable shrinkage to 0.70% or lower while maintaining mechanical strength and hardness, enhancing the performance of cable jacket compositions for high-density fiber optic cables.
Implementation Method 1
a MgCl2-supported catalyst prepared according to a method comprising the steps of: a) providing solid carrier particles of MgCl2*m OH adduct; b) pre-treating the solid carrier particles of step a) with a compound of Group 13 metal; c) treating the pre-treated solid carried particles of step b) with a transition metal compound of Group 4 to 6
Data Source
AI summary
The present invention relates to a cable jacket composition comprising a multimodal olefin copolymer, said copolymer having density of 0,935-0,960 g/cm3 and MFR2 of 2.2-10.0 g/10 min and said composition having ESCR of at least 2000 hours and a cable shrinkage of 0.70% or lower. The invention further relates to the process for preparing said composition and its use as outer jacket layer for a cable, preferably a communication cable, most preferably a fiber optic cable.