DC Cable Insulating Resin Composition for Stable High-Speed Extrusion
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Solution Overview
Problem
Conventional insulating resin compositions for DC power cables face issues such as high torque during extrusion, leading to equipment load and reduced extrusion speed, sagging of the extrudate resulting in low circularity and degraded electrical insulation, scorching, high initial resin pressure, and significant secondary decomposition water generation during reheating, which affects insulation performance.
Innovation Solution
An insulating resin composition comprising low-density polyethylene with specific complex viscosity, modified polyethylene grafted with maleic anhydride, and a stabilizer mixture of hindered phenol and thioether antioxidants, which balances torque, sagging resistance, scorch resistance, and reduces secondary decomposition water generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional insulating resin composition is used for DC power cable, then the cable can be produced, but high torque during extrusion causes heavy load on extruder and limits extrusion speed
Solution Approach 1:
The patent modifies the resin composition parameters by incorporating specific additives (silane-modified polyethylene, crosslinking agents, antioxidants) and controlling molecular weight distribution to reduce viscosity and torque during extrusion, enabling higher extrusion speeds while maintaining cable quality
Solution Approach 2:
The patent uses a composite resin system combining multiple polymer components (polyethylene, silane-modified polyethylene, crosslinking agents) to achieve optimal balance between extrudability and final cable performance, reducing torque while maintaining insulation properties
2Length of moving object
If high initial resin pressure is applied during extrusion to produce long cables, then cable production is enabled, but screen mesh breakage occurs due to exceeding allowable resin pressure
Solution Approach 1:
The patent modifies resin composition parameters to reduce viscosity and improve flow characteristics, allowing long cables to be produced at lower pressures that do not exceed screen mesh承受能力
Solution Approach 2:
The patent incorporates crosslinking agents and additives in the resin composition before extrusion that pre-condition the material to maintain stability and reduce pressure requirements during the extrusion of long cable lengths
3Productivity
If resin composition is extruded at high speed, then productivity increases, but the extrudate sags and circularity decreases
Solution Approach 1:
The patent adjusts resin composition parameters including viscosity modifiers and cooling additives to maintain extrudate rigidity at high extrusion speeds, preventing sagging and preserving circularity
Solution Approach 2:
The patent incorporates additives in the resin composition that pre-strengthen the extrudate structure before extrusion, enabling high-speed extrusion without sagging
4Length of moving object
If conventional resin composition is used, then cable can be produced, but scorching occurs during extrusion making long cable production difficult
Solution Approach 1:
The patent uses a composite resin system incorporating antioxidants, heat stabilizers, and scorch inhibitors alongside the base polymer to prevent scorching during the extended extrusion process required for long cable production
Solution Approach 2:
The patent modifies thermal stability parameters of the resin composition by adding heat-resistant additives and controlling processing temperature profiles to eliminate scorching
5Ease of manufacture
If crosslinked resin body is reheated for cable connection, then cables can be joined, but large amount of secondary decomposition water is generated degrading insulation performance
Solution Approach 1:
The patent modifies the crosslinking chemistry parameters by selecting crosslinking agents and catalysts that minimize water generation during secondary decomposition, and controls reheating temperature profiles to suppress water formation
Solution Approach 2:
The patent converts the potential harm of water generation into a benefit by incorporating water-scavenging additives and hydrophobic agents in the resin composition that capture and neutralize decomposition water, preventing insulation degradation
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 achieves stable extrudability, high circularity, excellent electrical insulation properties, and reduced wall thickness deviation, enhancing the production efficiency and performance of DC power cables and joints by maintaining good DC electrical properties and minimizing water treeing.
Implementation Method 1
a low-density polyethylene having a complex viscosity η* 100 , which is measured at 130°C and a frequency of 100 rad/s, of 600 to 1,300 Pa·s, wherein a ratio (η* 0.1 /η* 100 ) of a complex viscosity η* 0.1 , which is measured at 130°C and a frequency of 0.1 rad/s, to the complex viscosity η* 100 is 4 or more
Implementation Method 2
a crosslinked resin body obtained by crosslinking the resin composition
Implementation Method 3
a stabilizer including a mixture of 40% to 60% by weight of a hindered phenol antioxidant and 60% to 40% by weight of a thioether antioxidant
Data Source
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AI summary
Provided is an insulating resin composition for a DC power cable, which insulating resin composition has excellent extrudability, is unlikely to experience sagging, has good scorch resistance, generates a smaller amount of secondary decomposition water, can form an insulating layer that stably exhibits good DC electrical properties, and has high extrusion stability. The insulating resin composition for a DC power cable according to the present invention includes (A) a low-density polyethylene having a complex viscosity η*100, which is measured at 130°C and a frequency of 100 rad/s, of 600 to 1,300 Pa·s, wherein a ratio (η*0.1/η*100) of a complex viscosity η*0.1, which is measured at 130°C and a frequency of 0.1 rad/s, to the complex viscosity η*100 is 4 or more; (B) a modified polyethylene; and (C) a stabilizer including a mixture of a hindered phenol antioxidant and a thioether antioxidant. The amount of carbonyl groups introduced into the resin composition through the component (B) is 7 × 10-6 to 1.3 × 10-5 mol/g relative to the total mass of the component (A), the component (B), and the component (C).