Tire Rubber Composition with Modified Liquid Diene Rubber

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Solution Overview

Problem

Pneumatic tires face challenges in achieving satisfactory dry grip, wet grip, ice grip, and steering stability while maintaining abrasion resistance, as existing solutions often compromise on processability and long-term performance due to the use of high glass transition temperature rubbers and carbon black or silica, which affect flexibility and durability.

Innovation Solution

A tire rubber composition comprising a solid rubber with a low glass transition temperature, a modified liquid diene rubber with specific functional groups, and a filler such as silica or carbon black, which enhances mechanical strength, flexibility, and grip performance by improving the dispersion and reinforcement of fillers within the rubber matrix.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high glass transition temperature rubbers and large amounts of carbon black are used to enhance dry grip performance, then dry grip performance is improved, but viscosity increases and processability deteriorates

Engineering Contradiction:

Improvedry grip performanceVSAvoidprocessability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the glass transition temperature parameter of the rubber from high-Tg (conventional SBR) to low-Tg (not more than -10°C), and modifies the carbon black particle size parameter to ultra-fine range (5-100 nm). These parameter changes enable achieving high dry grip performance while maintaining acceptable viscosity and processability through the synergistic effect of low-Tg rubber providing flexibility and ultra-fine carbon black providing reinforcement without excessive thickening.

Inventive Principle:

Principle #35Parameter changes

2Strength

If carbon black or silica is added to enhance abrasion resistance, then abrasion resistance is improved, but processability deteriorates

Engineering Contradiction:

Improveabrasion resistanceVSAvoidprocessability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the particle size parameter of carbon black to ultra-fine range (5-100 nm) and uses silica as an alternative filler. Ultra-fine particles provide superior reinforcement efficiency and abrasion resistance at lower loading levels compared to conventional carbon black, thereby improving abrasion resistance while minimizing the viscosity increase and maintaining better processability.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If softeners such as oils are added to enhance flexibility, then flexibility is improved, but dry grip performance, wet grip performance, and abrasion resistance are insufficient

Engineering Contradiction:

ImproveflexibilityVSAvoidgrip performance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent replaces softeners (oils) with a composite system consisting of low-Tg solid rubber and ultra-fine fillers (carbon black 5-100 nm and silica). The low-Tg rubber provides flexibility through its molecular structure rather than plasticization, while the ultra-fine fillers provide reinforcement. This composite approach achieves flexibility without the performance penalties associated with oil softeners, maintaining grip performance and abrasion resistance.

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 rubber composition achieves excellent abrasion resistance, dry grip, wet grip, and ice grip performance, along with enhanced steering stability, while maintaining good processability and preventing long-term property deterioration.

Implementation Method 1

a modified liquid diene rubber (B) having a functional group derived from a silane compound

Methodology Applied

Scientific EffectSilane crosslinking: Chemical Bonding

Implementation Method 2

20 to 200 parts by mass of a filler (C)... improving the dispersion and reinforcement of fillers within the rubber matrix

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 3

a solid rubber (A) having a glass transition temperature (Tg) of not more than -10°C... enhancing the flexibility of tires at low temperatures

Methodology Applied

Scientific EffectGlass transition:

Data Source

PatentEP3677637B1Tire rubber compositions

Publication Date: 2023.03.01 KURARAY CO LTD

AI summary

The invention provides a tire rubber composition capable of giving crosslinked products having excellent properties including mechanical strength such as abrasion resistance, a crosslinked product of the composition, and a tire tread, a bead filler, a tire belt and a pneumatic tire which each partially include the composition or the crosslinked product and which each exhibit satisfactory dry grip performance plus excellent wet grip performance and ice grip performance and can attain enhanced steering stability. The tire rubber composition includes 100 parts by mass of a solid rubber (A) having a glass transition temperature (Tg) of not more than -10°C, 0.1 to 50 parts by mass of a modified liquid diene rubber (B) having a functional group derived from a silane compound with a specific structure, and 20 to 200 parts by mass of a filler (C), the modified liquid diene rubber (B) satisfying the following (i) to (iv): (i) the weight average molecular weight (Mw) is not less than 1,000 and less than 15,000, (ii) the vinyl content is not more than 70 mol%, (iii) the average number of the functional groups per molecule of the modified liquid diene rubber (B) is 1 to 20, and (iv) the glass transition temperature (Tg) is not more than 0°C.