Retreaded Tire Rubber Composition Aggregate Control
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Solution Overview
Problem
Conventional retreaded tire rubber compositions do not adequately reduce aggregates that cause rubber cracks, leading to insufficient resistance against crack growth, which is critical for durable and safe tires, especially for heavy-duty applications like aircraft tires.
Innovation Solution
A rubber composition with a specific aggregate density distribution, incorporating zinc oxide, fatty acid, and zinc salt of fatty acid, where the integrated value of white areas by particles for diameter 29 µm or more is 15% or less, and the total content of these components is between 2 and 13 parts by weight per 100 parts of rubber, significantly reducing fracture nucleuses and enhancing crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rubber compositions are used for retreaded tires, then production cost and environmental load reduction are achieved, but aggregate formation occurs which reduces resistance against crack growth
Solution Approach 1:
The patent applies parameter changes by precisely controlling the total content of zinc oxide, fatty acid, and zinc salt of fatty acid to be 2-13 parts by weight per 100 parts by weight of rubber. This specific compositional parameter range prevents aggregate formation while maintaining crack resistance, directly resolving the contradiction between reliability and harmful aggregate formation.
Solution Approach 2:
The patent uses a composite material approach by combining zinc oxide, fatty acid, and zinc salt of fatty acid in specific proportions within the rubber composition. This composite system works synergistically to prevent aggregate formation while enhancing resistance against crack growth, transforming the harmful aggregate formation into a beneficial composite structure.
2Reliability
If aggregates are reduced in rubber composition, then crack resistance should improve, but conventional techniques do not describe the mechanism or sufficient reduction
Solution Approach 1:
The patent establishes precise parameter thresholds for aggregate control, specifying that the integrated value of white areas by particles for diameter of 29 µm or more must be 15% or less of the integrated value of white areas by particles for diameter from 3 to 57 µm. This quantitative parameter control achieves both crack resistance improvement and manufacturing precision.
Solution Approach 2:
The patent replaces mechanical aggregate reduction methods with a chemical composition control approach. By optimizing the chemical composition (zinc oxide, fatty acid, zinc salt of fatty acid ratios), the patent achieves aggregate control without relying on mechanical processing, thereby improving both crack resistance and manufacturing precision simultaneously.
3Strength
If zinc salt of fatty acid content is increased to improve crack resistance, then fracture nucleuses increase forming aggregates, but precise control within 2-13 parts by weight prevents this
Solution Approach 1:
The patent applies parameter changes by defining a specific quantity range for zinc salt of fatty acid (2-13 parts by weight per 100 parts by weight of rubber). Within this parameter range, the zinc salt provides sufficient fracture resistance while preventing excessive aggregate formation. This precise parameter control resolves the contradiction between strength improvement and quantity control.
Solution Approach 2:
The patent uses fatty acid and zinc oxide as intermediary substances that mediate between zinc salt of fatty acid and the rubber matrix. These intermediaries help distribute the zinc salt uniformly, preventing aggregate formation while maintaining fracture resistance, thus resolving the contradiction between strength and quantity.
Data Source
AI summary
The purpose of the present invention is to provide a retreaded tire including a case rubber using a rubber composition for tires which has a specific aggregate density and a specific composition to prevent the formation of aggregates having a relatively large particle diameter causing cracks in a rubber. Thus, a retreaded tire having high resistance against crack growth, in particular, a heavy-duty retreaded tire including one for aircrafts is provided. The retreaded tire of the present invention is characterized by including a case rubber obtained from a rubber composition in which, the integrated value of white areas by particles for diameter of 29 µm or more is 15% or less of the integrated value of white areas by particles for diameter from 3 to 57 µm in an examoination of a cross-section of the rubber composition with a dispergrader based on ASTM D7723. The rubber composition contains zinc oxide, a fatty acid, and a zinc salt of fatty acid in a total amount of 2 parts by weight or more but less than 13 parts by weight per 100 parts by weight of the rubber.