Iron-Aluminum Zinc Oxide for Moist-Heat Steel Cord Adhesion

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Solution Overview

Problem

Existing rubber compositions for pneumatic tires lack sufficient adhesion between steel cords and vulcanized rubber, particularly in maintaining peel force over time, especially under moist heat conditions.

Innovation Solution

Incorporating zinc oxide with specific metallic compositions, specifically containing 15 ppm to 100 ppm of iron and 40 ppm to 100 ppm of aluminum, or an iron-to-aluminum ratio of 0.2 to 2.3, into the rubber composition to enhance the peel force from steel cords, utilizing either the American or French process for zinc oxide production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional zinc oxide is added to rubber composition, then basic vulcanization function is achieved, but peel force from steel cord is insufficient

Engineering Contradiction:
Improvepeel forceVSAvoidadhesion durability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention changes the metallic composition parameters of zinc oxide by controlling the content of iron (15-100 ppm) and aluminum (40-100 ppm) impurities. This parameter optimization transforms conventional zinc oxide into a specialized additive that significantly enhances peel force and adhesion durability between rubber and steel cord.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality by introducing specific metallic impurities (iron and aluminum) in controlled amounts into the zinc oxide structure. These localized metallic components create enhanced interaction sites at the rubber-steel cord interface, improving adhesion without affecting the bulk properties of the rubber composition.

Inventive Principle:
Principle #3Local quality

2Strength

If zinc oxide with high purity is used, then rubber composition stability is maintained, but peel force improvement is insufficient

Engineering Contradiction:
Improvepeel forceVSAvoidzinc oxide purity
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention redefines the purity parameters of zinc oxide by establishing optimal ranges for metallic impurities rather than demanding complete purity. By specifying iron content at 15-100 ppm and aluminum content at 40-100 ppm, the invention transforms the purity concept from a minimization target to an optimized parameter that enhances performance.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If conventional rubber composition is used, then basic tire performance is achieved, but adhesion between steel cord and vulcanized rubber deteriorates under moist heat conditions

Engineering Contradiction:
Improveadhesion durabilityVSAvoidmoist heat degradation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention converts the typically harmful effect of moist heat on adhesion into a beneficial condition by using zinc oxide with specific metallic composition. The iron and aluminum components in the optimized zinc oxide create a protective interaction at the rubber-steel cord interface that prevents degradation under moist heat, transforming environmental stress into a condition that demonstrates enhanced durability.

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

Data Source

PatentUS20240092997A1Zinc oxide, rubber composition for rubber-steel cord composites, and pneumatic tire
Publication Date: 2024.03.21 TOYO TIRE CORP

AI summary

A rubber composition comprising a zinc oxide which comprises aluminum and iron. The zinc oxide's content of the iron is preferably 15 ppm or more and 100 ppm or less and the zinc oxide's content of the aluminum is 40 ppm or more and 100 ppm or less. The zinc oxide's ratio of a content of the iron to a content of the aluminum is preferably 0.2 to 2.3. The zinc oxide's content of the iron is preferably 15 ppm or more and 80 ppm or less. The rubber composition is used for rubber-steel cord composites.