Power Cable Insulating Resin Composition for Water Tree Suppression

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Solution Overview

Problem

Existing insulating resins for electric power cables, such as crosslinked polyethylene (XLPE), are not recyclable and suffer from water tree growth and increased dielectric loss tangent due to the addition of hydrophilic molecules to suppress water tree growth, which degrades cable performance.

Innovation Solution

A non-crosslinked insulating resin composition comprising polypropylene, an elastomer, a modified monomer graft resin, and a water tree retardant, which suppresses water tree growth and reduces dielectric loss tangent, allowing for recyclability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hydrophilic molecule is added to suppress water tree growth, then water tree growth is suppressed, but the dielectric loss tangent increases

Engineering Contradiction:

Improvewater tree growth suppressionVSAvoiddielectric loss tangent

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the molecular weight parameter of the hydrophilic molecule (polyethylene glycol) to a specific high range (10,000-1,000,000), which fundamentally alters how the additive interacts with the resin system. This parameter change allows the additive to suppress water tree growth while minimizing dielectric loss tangent increase, resolving the contradiction between reliability improvement and energy loss.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite resin composition by combining polypropylene (main resin) with high molecular weight polyethylene glycol (hydrophilic additive) and optionally other polymers. This composite approach allows the system to achieve both water tree suppression and acceptable dielectric properties by leveraging the synergistic effects of different materials with complementary characteristics.

Inventive Principle:

Principle #40Composite materials

2Reliability

If XLPE is used for insulation, then water tree growth can be suppressed by adding hydrophilic molecules, but the cable becomes non-recyclable

Engineering Contradiction:

Improvewater tree suppressionVSAvoidrecyclability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using crosslinked polyethylene (XLPE) and attempting to add recyclability through additives, the patent inverts the approach by starting with recyclable polypropylene as the base resin. This fundamental inversion allows the cable insulation to be recyclable while still achieving water tree suppression through the high molecular weight polyethylene glycol additive.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If polypropylene is used as a thermoplastic insulating resin, then recyclability is achieved, but water tree occurs similarly to XLPE

Engineering Contradiction:

ImproverecyclabilityVSAvoidwater tree resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces high molecular weight polyethylene glycol as an intermediary substance that mediates between the polypropylene resin and water. This intermediary absorbs and disperses moisture uniformly throughout the resin, preventing moisture concentration at interfaces where water trees would normally initiate and propagate, thereby providing water tree resistance to the recyclable polypropylene insulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively suppresses water tree growth and decreases dielectric loss tangent, enhancing recyclability and power transmission efficiency while maintaining cable integrity.

Implementation Method 1

hydrophilic molecules, e.g., polyethylene glycols, are added to hydrophobic polyethylene. Since moisture uniformly disperses in the XLPE resin by way of the hydrophilic molecules such as polyethylene glycols, the concentration of moisture on the interface of the foreign substances and voids is curbed

Methodology Applied

Scientific EffectHydrophilic molecule absorption: Absorption (physical)

Implementation Method 2

even if a polypropylene which is a thermoplastic resin, since the addition of a hydrophilic molecule increases the dielectric loss tangent (tan δ) of the resin, the electric power transmission efficiency of the electric power cable declines

Methodology Applied

Scientific EffectDielectric loss: Dielectric

Data Source

PatentUS20250215202A1Insulating resin composition for electric power cable and electric power cable

Publication Date: 2025.07.03 FURUKAWA ELECTRIC CO LTD

AI summary

This insulating resin composition for electric power cable includes a component (a), a component (b), a component (c), and a component (d), in which the component (a) is polypropylene, the component (b) is an elastomer, the component (c) is at least one type of resin selected from a resin (c1) and a resin (c2), the resin (c1) being a resin in which at least one type of modified monomer selected from unsaturated organic acid and derivative thereof is grafted, and the resin (c2) being at least one type of ethylene-based copolymer selected from an ethylene-acrylate copolymer, ethylene-acrylic acid copolymer, and ethylene-vinyl acetate copolymer, and the component (d) is a water tree retardant.