Rubber Composition Mixing Process for Tire Tread Fatigue Resistance

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Solution Overview

Problem

Existing rubber compositions for vulcanized tires, particularly tire treads, face challenges in improving bending fatigue resistance due to insufficient interaction between carbon black and rubber, and the previous techniques fail to effectively incorporate silica, leading to deteriorated workability and dispersibility.

Innovation Solution

A method involving a two-step mixing process where a diene rubber, carbon black, and dihydrazide compound react initially without silica to enhance their interaction, followed by the addition of silica to maintain strong interaction between the diene rubber and carbon black, ensuring improved dispersibility and bending fatigue resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a dihydrazide compound is blended with reinforcing-filler and rubber to heighten dispersibility, then the interaction between carbon black and rubber is improved, but the workability of the rubber composition is deteriorated

Engineering Contradiction:
Improveinteraction between carbon black and rubberVSAvoidworkability of rubber composition
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The dihydrazide compound is caused to react with carbon black in advance during the first mixing step before silica is added in the second mixing step. This preliminary reaction establishes strong interaction between carbon black and rubber while avoiding the hindering effect of silica, thereby maintaining good workability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The mixing process is divided into two distinct steps: first mixing carbon black with diene rubber and dihydrazide compound without silica to establish strong interaction, then adding silica in the second mixing step. This segmentation allows each component to be incorporated optimally without interfering with the carbon black-rubber interaction.

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If silica is added to the rubber composition to improve dispersibility, then the dispersibility of reinforcing-filler is enhanced, but the reaction between dihydrazide compound and carbon black is hindered by silanol groups

Engineering Contradiction:
Improvedispersibility of reinforcing-fillerVSAvoidinteraction between carbon black and rubber
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The dihydrazide compound reacts with carbon black in advance during the first mixing step before silica is introduced. This preliminary action ensures that the carbon black-rubber interaction is established while the dihydrazide compound is still reactive and not hindered by silanol groups from silica.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The addition of silica is separated into a second mixing step, occurring after the carbon black-dihdrazide-rubber reaction has already taken place. This temporal and procedural segmentation prevents silanol groups from interfering with the carbon black-dihdrazide interaction while still achieving good silica dispersibility.

Inventive Principle:
Principle #1Segmentation

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 method produces a rubber composition with strong interaction between diene rubber and carbon black, resulting in vulcanized rubber with enhanced bending fatigue resistance and improved endurance for tire treads.

Implementation Method 1

a dihydrazide compound reacts with a diene-based polymer and a carbon black to contribute to an improvement in interaction between the diene rubber and the carbon black

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

reaction between a dihydrazide compound and a carbon black is hindered by the interaction between silanol groups present in the silica surface, and the dihydrazide compound

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 3

a second mixing step of adding a silica to the kneaded product yielded through the first mixing step, and then mixing the silica with the kneaded product

Methodology Applied
Scientific EffectMechanical mixing and dispersion:

Data Source

PatentUS9296873B2Method for producing rubber composition
Publication Date: 2016.03.29 TOYO TIRE CORP

AI summary

A method for producing a rubber composition, comprising a first mixing step of causing a diene rubber, a carbon black, and a dihydrazide compound to react with each other in the presence of no silica while the three of the diene rubber, the carbon black, and the dihydrazide compound are kneaded, and a second mixing step of adding a silica to the kneaded product yielded through the first mixing step, and then mixing the silica with the kneaded product.