Rubber Composition Balancing Aged Tackiness and Crack Resistance

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Solution Overview

Problem

Existing rubber compositions face issues with deteriorated tackiness after aging, particularly when using cobalt acetylacetonate, which affects the adhesion and crack resistance of rubber articles.

Innovation Solution

A rubber composition comprising an elastomer matrix with polyisoprene, a reinforcing filler, cobalt acetylacetonate, and a fatty acid with over 10% unsaturated fatty acid, in specific proportions, enhances tackiness and crack resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If cobalt acetylacetonate is used in rubber composition, then breaking properties are improved, but tackiness after aging deteriorates

Engineering Contradiction:
Improvebreaking propertiesVSAvoidtackiness after aging
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

A fatty acid is introduced as an intermediary substance between cobalt acetylacetonate and the elastomer matrix. The fatty acid content is controlled at 0.1-2.0 phr to mediate the interaction, preventing cobalt acetylacetonate from deteriorating tackiness after aging while preserving its breaking property enhancement

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The composition parameters are precisely controlled: cobalt acetylacetonate at 0.1-2.0 phr, fatty acid at 0.1-2.0 phr with more than 10% unsaturated fatty acid content, and polyisoprene at more than 50 phr. These parameter optimizations resolve the contradiction by finding the balanced range where both breaking properties and aged tackiness are improved

Inventive Principle:
Principle #35Parameter changes

2Strength

If cobalt acetylacetonate is used to enhance breaking properties, then initial tackiness may be maintained, but adhesion and crack resistance are affected

Engineering Contradiction:
Improvebreaking propertiesVSAvoidcrack resistance
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The fatty acid acts as a protective intermediary that shields the elastomer matrix from the harmful effects of cobalt acetylacetonate on crack resistance. By controlling the fatty acid content at 0.1-2.0 phr, the composition maintains crack resistance while still benefiting from improved breaking properties

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The potentially harmful effect of cobalt acetylacetonate on crack resistance is converted into a benefit through the addition of fatty acid. The fatty acid transforms the negative interaction into a positive outcome where both breaking properties and crack resistance are improved simultaneously

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP4210970B1A rubber composition
Publication Date: 2025.08.06 MICHELIN & CO (CIE GEN DES ESTAB MICHELIN)

AI summary

A rubber composition is based on an elastomer matrix, a reinforcing filler, a cobalt acetylacetonate and a fatty acid based on more than 10% by weight an unsaturated fatty acid per 100% by weight of the fatty acid.