Sulfur-Crosslinkable Rubber Mixture for Tire Rolling Resistance

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Solution Overview

Problem

Existing sulfur-crosslinkable rubber mixtures for vehicle tires face challenges with poor storage stability and processability due to reactive functional groups, leading to fluctuations in rolling resistance and tire properties.

Innovation Solution

A sulfur-crosslinkable rubber mixture comprising diene rubber with a weight average molecular weight of 100,000 to 5,000,000 g/mol and a butadiene-based functionalized polymer with a weight average molecular weight of 1000 to 20,000 g/mol, where the polymer is branched via an organic group with functional groups, reducing reactivity and improving storage stability and processability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If functionalized polymers with chain-end functional groups are used to improve rolling resistance, then rolling resistance behavior is improved, but storage stability deteriorates due to high reactivity

Engineering Contradiction:
Improverolling resistanceVSAvoidstorage stability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent segments the functional groups from the polymer chains by using a separate multifunctional compound (crosslinking agent) that contains multiple reactive groups. This crosslinking agent acts as a bridge between polymer chains, providing the desired network structure without requiring highly reactive chain-end functional groups, thus improving storage stability while maintaining rolling resistance performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a multifunctional crosslinking agent as an intermediary substance that mediates the crosslinking process. This intermediary contains multiple reactive groups that can react with unsaturation in the rubber matrix, forming a three-dimensional network without requiring the polymer chains themselves to be highly reactive, thereby resolving the contradiction between reactivity and storage stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If functionalized polymers with high reactivity are used to achieve improved rolling resistance, then rolling resistance is improved, but processability deteriorates due to fluctuations in mixture properties

Engineering Contradiction:
Improverolling resistanceVSAvoidprocessability
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent separates the functionalization function from the polymer chains and assigns it to a dedicated multifunctional crosslinking agent. This segmentation allows for better control of the crosslinking process and more consistent mixing behavior, as the crosslinking agent can be added in controlled amounts and reacts predictably with the rubber matrix, improving processability while maintaining the desired rolling resistance performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameters of the crosslinking system by using a multifunctional crosslinking agent with controlled reactivity and multiple functional groups. This allows for adjustment of the crosslinking density and network structure, providing better control over the vulcanization process and resulting in more consistent mixture properties and improved processability.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If branched polymers are used to improve processability, then processability is improved, but molecular weight distribution control becomes more difficult

Engineering Contradiction:
ImproveprocessabilityVSAvoidmolecular weight distribution
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent uses a multifunctional crosslinking agent as an intermediary to create the branched and crosslinked structure in the rubber matrix. This approach allows for controlled introduction of branches and crosslinks without requiring complex branched polymer synthesis, thereby maintaining precise control over molecular weight distribution while achieving improved processability through the resulting network structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution results in improved rolling resistance, handling behavior, and consistent tire properties, including resistance to crack formation, abrasion, and braking performance, while maintaining or enhancing winter properties and reducing production complexity.

Implementation Method 1

a sulfur-crosslinkable rubber mixture containing at least one diene rubber and at least one butadiene-based functionalized polymer

Methodology Applied
Scientific EffectSulfur crosslinking: Chemical Bonding

Implementation Method 2

the polymer is branched via at least one organic group containing at least one functional group, so that two or more butadiene-based polymer chains are attached to the at least one organic group

Methodology Applied
Scientific EffectBranching effect:

Data Source

PatentEP2987813B1Sulphur linkable natural rubber mixture and vehicle tyre
Publication Date: 2018.12.26 CONTINENTAL REIFEN DEUTSCHLAND GMBH

AI summary

The invention relates to a sulfur-crosslinkable rubber compound comprising at least one butadiene-based functionalized polymer with a weight-average molecular weight (Mw) according to GPC of 500 to 45,000 g/mol, and a vehicle tire incorporating the sulfur-crosslinkable rubber compound in at least one component. The polymer is branched via at least one organic group comprising at least one functional group, such that two or more butadiene-based polymer chains are attached to the at least one organic group.