Heavy-Duty Tire Cap-Base Rubber Layout for Grip and Rolling Loss

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Solution Overview

Problem

Conventional methods for improving tire fuel efficiency, wet grip performance, abrasion resistance, chipping resistance, and tear resistance are limited, particularly for heavy-duty tires, as micronized carbon black can deteriorate dispersibility and abrasion resistance.

Innovation Solution

A heavy-duty tire design featuring a cap rubber layer with a specific rubber composition including isoprene-based rubber and styrene-butadiene rubber, and a base rubber layer with controlled loss tangent, combined with a silica network for enhanced strength and hydrophilicity, along with a specific thickness distribution and silane coupling agent, to achieve balanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If carbon black is micronized to improve abrasion resistance, then abrasion resistance is improved, but dispersibility deteriorates

Engineering Contradiction:
Improveabrasion resistanceVSAvoiddispersibility
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent changes the particle size parameter of carbon black from micronized to ultra-fine (average primary particle size 0.01 to 0.05 μm), which simultaneously improves abrasion resistance and maintains dispersibility. This parameter optimization resolves the contradiction between wear resistance and material distribution uniformity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite rubber composition combining ultra-fine carbon black with specific rubber components (natural rubber, S-SBR, E-SBR, BR) and silane coupling agents. This composite structure ensures both high abrasion resistance through fine carbon black reinforcement and good dispersibility through compatible rubber matrix and coupling agents.

Inventive Principle:
Principle #40Composite materials

2Reliability

If silica content is increased to improve wet grip performance, then wet grip performance is improved, but processing complexity increases

Engineering Contradiction:
Improvewet grip performanceVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces silane coupling agents as intermediaries between silica and rubber components. These coupling agents facilitate the interaction between hydrophilic silica and hydrophobic rubber, improving wet grip performance while simplifying processing by enabling better dispersion and bonding without complex manufacturing steps.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent optimizes silica particle size parameters (average primary particle size 0.01 to 0.1 μm) and controls silica content within specific ranges (10-50 parts by weight per 100 parts rubber component). This parameter optimization achieves high wet grip performance while maintaining manageable processing complexity.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If rolling resistance is reduced to improve fuel efficiency, then fuel efficiency is improved, but wet grip performance may deteriorate

Engineering Contradiction:
Improvefuel efficiencyVSAvoidwet grip performance
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent carefully balances the loss tangent (tan δ) at 70°C within the range of 0.04 to 0.08, which simultaneously reduces rolling resistance for improved fuel efficiency and maintains adequate wet grip performance. This precise parameter control resolves the contradiction between energy efficiency and safety performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite system combining ultra-fine carbon black, silica, and specific rubber components that work together to achieve low rolling resistance while maintaining wet grip. The synergistic interaction of these materials allows independent optimization of fuel efficiency and wet grip performance.

Inventive Principle:
Principle #40Composite materials

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 tire exhibits improved fuel efficiency, wet grip performance, abrasion resistance, chipping resistance, and tear resistance with a good balance, as demonstrated by specific performance indices and test results.

Implementation Method 1

a rubber composition comprising a rubber component and silica

Methodology Applied
Scientific EffectSilica network formation:

Implementation Method 2

8 to 18 parts by mass of a sulfide-based silane coupling agent

Methodology Applied
Scientific EffectSilane coupling: Chemical Bonding

Implementation Method 3

a tan δ of the base rubber layer within a predetermined range

Methodology Applied
Scientific EffectViscoelasticity: Viscoelasticity

Data Source

PatentEP3960494B1Heavy duty tire
Publication Date: 2023.11.01 SUMITOMO RUBBER INDUSTRIES LTD
  • EP3960494B1 patent drawingFigure 1
  • EP3960494B1 patent drawingFigure 2
  • EP3960494B1 patent drawing

AI summary

An object of the present invention is to provide a heavy duty tire having improved fuel efficiency, wet grip performance, abrasion resistance, chipping resistance, and tear resistance with good balance. The heavy duty comprises a carcass (12) extending from a tread part (22) through a sidewall part (6) to a bead core of a bead part and a belt layer (18) arranged outside in a tire radial direction of the carcass and inside of the tread part, wherein the tread has a cap rubber layer (30) and a base rubber layer (28), the cap rubber layer comprises a predetermined rubber component and silica and the loss tangent tan δ of the base rubber layer is within a predetermined range.