Silicone Composition for Power Cable Tracking Resistance

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Solution Overview

Problem

Silicone rubber compositions used for power cable connections face issues with tracking resistance and mechanical strength, particularly when exposed to outdoor conditions, leading to erosion and reduced lifespan, despite the need for high aluminum hydroxide content which compromises mechanical properties.

Innovation Solution

A silicone composition comprising a raw rubber-like organopolysiloxane with alkenyl groups, silica powder, platinum or platinum compounds, an organic silicon compound with a nitrogen-containing group and unsaturated hydrocarbon, benzotriazole, and an aromatic hydrocarbon group-containing organopolysiloxane, which provides excellent tracking resistance and mechanical strength without relying on aluminum hydroxide.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large content of aluminum hydroxide is added to improve tracking resistance, then electrical insulation property is improved, but mechanical strength is worsened

Engineering Contradiction:

Improvetracking resistanceVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters by replacing aluminum hydroxide with a specific combination of silica powder (5-100 parts by mass) and titanium oxide (0.1-5 parts by mass) relative to 100 parts by mass of organopolysiloxane. This parameter substitution maintains tracking resistance while preserving mechanical strength properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite filler system combining silica powder and titanium oxide in specific proportions. This composite approach provides both the electrical insulation and tracking resistance needed while avoiding the mechanical strength degradation caused by aluminum hydroxide alone.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If silicone rubber is used outdoors, then good restorability and sealing properties are achieved, but tracking occurs under leakage current leading to erosion

Engineering Contradiction:

ImproverestorabilityVSAvoidtracking and erosion

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces titanium oxide as an intermediary substance that mediates between the silicone rubber matrix and the environmental factors causing tracking. The titanium oxide particles (0.1-5 parts by mass) work synergistically with silica powder to prevent leakage current tracking while maintaining the rubber's elastic recovery properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the compositional parameters by incorporating specific amounts of benzotriazole (0.01-0.5 parts by mass) and the silica-titanium oxide filler system. These parameter changes enhance resistance to outdoor environmental factors including UV radiation and leakage current, preventing erosion while preserving restorability.

Inventive Principle:

Principle #35Parameter changes

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 small tensile permanent strain, high tensile and tear strength, and superior high-voltage electrical insulation, effectively preventing erosion progression and ensuring the integrity of power cable connections.

Implementation Method 1

5 to 100 parts by mass of silica powder having a specific surface area of 50 m2 or more per 100 parts by mass of the organopolysiloxane (A), 0.1 to 5 parts by mass of titanium oxide per 100 parts by mass of the organopolysiloxane (A)

Methodology Applied

Scientific EffectPhysical barrier effect:

Implementation Method 2

platinum or a platinum compound, an organic silicon compound with a nitrogen-containing group and unsaturated hydrocarbon

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 3

an organic silicon compound with a nitrogen-containing group and unsaturated hydrocarbon, benzotriazole

Methodology Applied

Scientific EffectChemical stability:

Implementation Method 4

superior high-voltage electrical insulation, effectively preventing erosion progression

Methodology Applied

Scientific EffectDielectric property: Dielectric

Data Source

PatentEP3473661B1Silicone composition, a cured silicone rubber product and a power cable

Publication Date: 2022.10.05 SHIN ETSU CHEMICAL CO LTD

AI summary

The present invention provides a silicone composition comprising components (A) to (F); (A) 100 parts by mass of a raw rubber-like, at 25 degrees C, organopolysiloxane having at least two alkenyl groups each bonded to a silicon atom; (B) 5 to 100 parts by mass of silica powder having a specific surface area of 50 m2/g or more; (C) platinum or a platinum compound in an amount of 1 to 1,000 ppm by mass as a platinum atom, relative to the mass of component (A); (D) 0.01 to 5 parts by mass of a compound selected from an organic silicon compound having a nitrogen-containing organic group and an unsaturated hydrocarbon group, and benzotriazole and a derivative thereof; (E) an addition reaction curing agent other than said component (C), or an organic peroxide in an effective amount to cure the composition, and (F) 0.01 to 5 parts by mass of an aromatic hydrocarbon group-containing organopolysiloxane represented by the general formula (1) wherein a proportion of the number of the monovalent aromatic hydrocarbon group to the total number of the substituents R1, R2 and R3 is 41 % or more and less than 46 %.