Crosslinkable Polymeric Cable Insulation Extrusion Speed
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Solution Overview
Problem
The high melt viscosity and filler content in existing crosslinked insulation materials for flexible power cables reduce extrusion speed and increase manufacturing costs, while also increasing cable density.
Innovation Solution
A crosslinkable polymeric composition comprising an ethylene-based interpolymer with specific properties and high-pressure polyethylene, combined with a controlled filler content, to enhance melt strength, shear thinning ratio, and extrusion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fillers such as calcined clay are incorporated to assure adequate pellet stability and melt strength, then sag resistance during extrusion is improved, but extrusion speed is reduced and cable density increases
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer blend, specifically using ethylene/propylene/diene interpolymer with controlled density (0.87-0.92 g/cm³) and melt index (0.1-10 g/10 min) to achieve adequate melt strength without requiring filler additions, thereby maintaining high extrusion speeds
Solution Approach 2:
The patent creates a composite polymer blend system combining ethylene/propylene/diene interpolymer with other compatible polymers to achieve synergistic effects where the blend provides both sag resistance and high extrusion speed that neither component could achieve alone
2Strength
If fillers such as calcined clay are incorporated to assure adequate pellet stability and melt strength, then sag resistance during extrusion is improved, but cable density increases
Solution Approach 1:
The patent changes the density parameter of the polymer blend by selecting ethylene/propylene/diene interpolymer with density of 0.87-0.92 g/cm³, which is lower than traditional filled compounds, achieving adequate melt strength without increasing cable density
Solution Approach 2:
The patent extracts and eliminates the need for heavy filler materials like calcined clay by using specially formulated interpolymer compositions that provide melt strength through their molecular structure rather than through filler reinforcement
3Strength
If high melt viscosity polymers are used to ensure sag resistance, then melt strength is improved, but extrusion speed is reduced
Solution Approach 1:
The patent optimizes the melt index parameter to a specific range (0.1-10 g/10 min) that provides adequate zero-shear viscosity for sag resistance while maintaining lower melt viscosity during extrusion through controlled shear thinning behavior, enabling high extrusion speeds
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 composition improves melt strength, reduces cable density, and increases extrusion speed, leading to cost-effective and efficient cable manufacturing with enhanced insulation properties.
Implementation Method 1
enhance melt strength, shear thinning ratio, and extrusion efficiency
Data Source
AI summary
Crosslinkable polymeric compositions comprising: (a) a polymer blend comprising: (1) 10 to 94 weight percent, based on the total weight of the crosslinkable polymeric composition, of an ethylene-based interpolymer having the following properties: (i) a density of 0.93 g/cm3 or less, (ii) a melt index (I 2 ) at 190 °C of greater than 0.2 g/10 minutes, and (iii) a shear thinning ratio (V0.1/V100) at 190 °C and 10 % strain of less than 8; and (2) 5 to 90 weight percent, based on the total weight of the crosslinkable polymeric composition, of a high-pressure polyethylene; and (b) 0 to less than 40 weight percent, based on the total weight of the crosslinkable polymeric composition, of a filler, where the ethylene-based interpolymer of component (a) is not prepared in a high-pressure reactor or process. Additionally, the polymer blend has the following properties: (i) a shear thinning ratio (V0.1/V100) at 190 °C and 10 % strain of at least 5, (ii) a high-shear viscosity (V100) at 190 C and 10 % strain of less than 1,300 Pa.s, (iii) a melt strength of at least 4 centiNewtons at 190 °C, and (iv) a flexural modulus, 2% secant, of less than 25,000 psi. Such crosslinkable polymeric compositions may be employed as insulation layers in flexible power cables.