Functionalized Rubber Mixture for Tire Tread Balance

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Solution Overview

Problem

Existing tire tread compositions face challenges in achieving a balance between improved winter properties, abrasion resistance, rolling resistance, and wet grip without compromising on processing ease, as traditional approaches often result in trade-offs between these performance metrics.

Innovation Solution

A sulfur-crosslinkable rubber mixture featuring a rubber blend of high molecular weight and low molecular weight solution-polymerized diene polymers, functionalized with groups like epoxy, hydroxy, and silane sulfide, combined with a specific vulcanization system, enhances processing and performance by optimizing filler-polymer interaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silica replaces carbon black in rubber mixtures to improve wet grip and dry braking, then wet grip and dry braking are improved, but rolling resistance deteriorates

Engineering Contradiction:
Improvewet gripVSAvoidrolling resistance
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent uses functionalized polymers with specific molecular weights and glass transition temperatures to modify the rubber mixture parameters. The low molecular weight functionalized polymer (5-50 phr) with Tg of -100 to -50°C changes the viscoelastic properties of the mixture, enabling optimization of the silica-rubber interface and reduction of hysteresis losses, thereby improving rolling resistance while maintaining wet grip performance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite rubber mixture system combining high molecular weight polymer, low molecular weight functionalized polymer, silica filler, and sulfur vulcanization system. This composite approach allows the functionalized polymer to act as a bridge between silica and the polymer matrix, improving filler dispersion and interaction while balancing wet grip and rolling resistance properties

Inventive Principle:
Principle #40Composite materials

2Reliability

If silica replaces carbon black in rubber mixtures to improve wet grip and dry braking, then wet grip and dry braking are improved, but abrasion behavior deteriorates

Engineering Contradiction:
Improvewet gripVSAvoidabrasion resistance
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The functionalized polymer with specific molecular weight (5-50 phr) and glass transition temperature (-100 to -50°C) modifies the rubber mixture parameters to enhance filler-polymer interaction. This improves the durability of the tread compound by creating stronger bonds at the silica-rubber interface, thereby improving abrasion resistance while maintaining wet grip

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite system combines functionalized polymer, silica, and sulfur vulcanization to create a durable tread compound. The functional groups on the polymer chains interact with silica surface, creating a reinforced composite structure that resists abrasion while maintaining wet grip performance

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If functionalized polymer with low molecular weight is added to improve processing and performance, then processing behavior is improved, but the complexity of the rubber blend increases

Engineering Contradiction:
Improveprocessing behaviorVSAvoidrubber blend complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The functionalized polymer is designed with specific parameters (molecular weight, glass transition temperature, functional group content) that enable it to perform multiple functions: improving processing behavior through lower viscosity, enhancing filler interaction through functional groups, and contributing to vulcanization. This parameter optimization reduces the need for additional processing aids, effectively managing complexity

Inventive Principle:
Principle #35Parameter changes

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 rubber mixture exhibits improved winter properties, abrasion resistance, and rolling resistance while maintaining wet grip, with enhanced processing behavior even at high filler content, achieving a significant balance between these competing performance factors.

Implementation Method 1

The polymer B acts similarly to a plasticizer. This good processing behavior was even evident in mixtures with a high degree of filling and a high plasticizer content

Methodology Applied
Scientific EffectPlasticization:

Implementation Method 2

at least one of the polymers A or B has at least one of the polymers A or B at the chain end and/or along the polymer chain and/or in a coupling center with at least one group selected from epoxy groups, hydroxy groups, carboxy groups, silane sulfide groups

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 3

a sulfur-crosslinkable rubber mixture containing a rubber blend... a vulcanization system... the molar ratio of accelerator to sulfur (accelerator/sulfur ratio) being 0.18 to 5

Methodology Applied
Scientific EffectVulcanization: Chemical Bonding

Data Source

PatentEP3500440B1Sulfur-crosslinkable rubber mixture and vehicle tire
Publication Date: 2021.10.06 CONTINENTAL REIFEN DEUTSCHLAND GMBH

AI summary

The invention relates to a sulfur-crosslinkable rubber mixture, containing: a rubber blend of at least one high-molecular-weight, solution-polymerized diene polymer A and at least one low-molecular-weight, solution-polymerized polymer B, wherein at least one of the polymers A or B is functionalized at the chain end and/or along the polymer chain and/or in a coupling center with at least one group selected from epoxy groups, hydroxy groups, carboxy groups, silane-sulfide groups, amino groups, siloxane groups, organosilicon groups, phthalocyanine groups, and from alkoxysilyl groups containing amino groups, and a vulcanization system, which contains at least one accelerator and elemental sulfur and/or at least one sulfur-donating substance, wherein the molar ratio of accelerator to sulfur is 0.18 to 5, wherein the total molar quantity of sulfur consists of elemental sulfur and the sulfur released by the sulfur-donating substances.