Mica Tape Insulation Catalyst Mixture for Rotating Machines

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Solution Overview

Problem

Conventional insulation coils face issues with shortened shelf life and reduced heat resistance due to the use of imidazole compounds as curing catalysts, leading to premature hardening and lowered glass transition temperatures, respectively.

Innovation Solution

Employing a mixture of epoxy adduct imidazole and zinc naphthenate as curing catalysts, which exhibit low catalytic activity at room temperature but high activity at elevated temperatures, preventing premature curing and enhancing heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an ordinary imidazole compound is used as curing catalyst, then the binder resin curing reaction occurs causing hardening of the mica tape, but the shelf life of the mica tape is shortened

Engineering Contradiction:

Improveinsulation reliabilityVSAvoidshelf life of mica tape

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical parameters of the curing catalyst by selecting specific compounds (2-methylimidazole or 2-ethyl-4-methylimidazole) with controlled catalytic activity. These compounds provide sufficient catalytic function for epoxy resin curing while having reduced activity toward binder resin, thereby extending shelf life while maintaining insulation reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent accepts that the mica tape has a limited shelf life (short-living) but optimizes it to be commercially viable. By using imidazole compounds that balance catalytic activity and stability, the shelf life is extended to a practical duration without compromising the ultimate insulation performance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Productivity

If zinc naphthenate is used as curing catalyst, then the gel time is shortened, but the glass transition temperature of the cured product is lowered causing deterioration of heat resistance

Engineering Contradiction:

Improvecuring speedVSAvoidglass transition temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent changes the chemical parameters of the curing catalyst to imidazole compounds that provide optimal balance between gel time and glass transition temperature. These compounds achieve sufficiently short gel time for production efficiency while maintaining high glass transition temperature for heat resistance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different catalyst characteristics to different functional requirements: the imidazole compound provides localized catalytic action sufficient for epoxy curing (productivity) while maintaining overall system stability for heat resistance. The catalyst's molecular structure is selected to achieve local optimization of both properties.

Inventive Principle:

Principle #3Local quality

3Reliability

If the binder resin is cured during preservation, then the mica tape hardens, but the conductor taping workability is deteriorated

Engineering Contradiction:

Improveinsulation reliabilityVSAvoidconductor taping workability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the chemical parameters of the curing system by selecting imidazole compounds with specific catalytic characteristics. These compounds maintain low reactivity during preservation (keeping the tape flexible and workable) while providing sufficient catalytic activity during the intended curing process to ensure insulation reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent designs the curing catalyst to remain dormant during preservation and activation only during the intended curing process. The imidazole compound is selected to not trigger premature binder resin curing, thereby preserving workability until the actual manufacturing stage when curing is desired.

Inventive Principle:

Principle #10Preliminary action

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

This combination prolongs the shelf life of insulating mica tapes, prevents epoxy resin composition run-off during curing, and achieves a cured product with high glass transition temperature, ensuring improved heat resistance and insulation reliability.

Implementation Method 1

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS8314342B2Winding applied single vacuum pressure impregnation insulation system, a winding applied global vacuum pressure impregnation insulation system and an electrical rotating machine having said insulation systems

Publication Date: 2012.11.20 MITSUBISHI GENERATOR CO LTD

AI summary

The present invention is designed to provide an insulation coil with high insulation reliability using a dry mica tape, an integral impregnation coil and a mica tape for the electrical rotating machines using these coils, said mica tape having a long shelf life and capable of preventing run-off of the impregnating epoxy resin composition during curing, with the cured product of said epoxy resin composition being high in heat resistance. It is also envisaged to provide a single insulation coil using a mica tape containing epoxy adduct imidazole as an epoxy resin curing catalyst or a mica tape containing a mixture of epoxy adduct imidazole and zinc naphthenate. An integral impregnation coil made by using said insulation coil and an epoxy resin composition, and the electrical rotating machines using such coils are also provided.