High Cis Block Copolymers for Tire Wear and Hysteresis Control

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Solution Overview

Problem

Existing methods for producing high 1,4-cis block copolymers of polybutadiene and polyisoprene lack control over polymer microstructure and are complicated by self-termination reactions, making it difficult to achieve high cis-content polymers suitable for tire components with optimal wear resistance and low-temperature properties.

Innovation Solution

A method involving a lanthanide-based catalyst system, including a lanthanide-containing compound, aluminoxane, and an organoaluminum compound, is used to polymerize 1,3-butadiene and isoprene, allowing for the production of block copolymers with a cis content of at least 90%, which are then vulcanized with a filler and curing agent to create tire components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If anionic polymerization techniques are used to prepare block copolymers, then block copolymers can be readily produced, but the polymer microstructure control is poor resulting in low or medium cis-1,4-linkage content

Engineering Contradiction:

Improveease of block copolymer productionVSAvoidcis-1,4-linkage content control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the polymerization parameters by switching from anionic polymerization to coordination polymerization using lanthanide-based catalysts. This parameter change enables precise control over the cis-1,4-linkage content, achieving greater than 90% cis-1,4 microstructure while maintaining block copolymer production capability.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If coordination-catalysis techniques are used to prepare high cis-1,4-linkage content polymers, then polymer microstructure control is improved, but the process becomes complicated with self-termination reactions making block copolymer preparation difficult

Engineering Contradiction:

Improvecis-1,4-linkage content controlVSAvoidpolymerization process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a specific intermediary system consisting of lanthanide-based catalysts combined with aluminoxane co-catalysts and chain transfer agents. This intermediary system mediates the polymerization process to prevent self-termination reactions while maintaining high cis-1,4-linkage content control, thereby simplifying the overall process for block copolymer preparation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a well-established coordination polymerization mechanism that has been successfully copied and adapted from homopolymerization to block copolymerization. By using the same lanthanide-based catalyst system with modified conditions, the proven microstructure control is replicated in the block copolymer synthesis, reducing process complexity.

Inventive Principle:

Principle #26Copying

3Strength

If high cis-1,4-linkage content is achieved in block copolymers, then wear resistance and mechanical properties are improved, but the polymerization process becomes more difficult to control

Engineering Contradiction:

Improvewear resistance and mechanical propertiesVSAvoidpolymerization process control difficulty

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent systematically changes multiple polymerization parameters including catalyst selection (lanthanide-based), co-catalyst type (aluminoxane), chain transfer agent presence, temperature, and monomer feed ratios. These coordinated parameter changes enable simultaneous achievement of high cis-1,4-linkage content (greater than 90%) for improved wear resistance and mechanical properties, while maintaining controllable polymerization processes.

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 resulting block copolymers exhibit enhanced wear resistance and low hysteretic loss, making them suitable for tire components with improved mechanical properties and temperature performance.

Implementation Method 1

Coordination-catalysis techniques allow for better control of the polymer microstructure and may be used to prepare polymers with a high cis-1,4-linkage content

Methodology Applied

Scientific EffectCoordination polymerization: Catalysis

Implementation Method 2

Polymers prepared with anionic initiators display living characteristics in that the polymer chains possess living ends that are capable of reacting with additional monomer for further chain growth

Methodology Applied

Scientific EffectLiving polymerization: Catalysis

Data Source

PatentUS11884767B2High cis-1,4 block copolymers of polybutadiene and polyisoprene

Publication Date: 2024.01.30 BRIDGESTONE CORP

AI summary

A vulcanizable composition comprising rubber component, a filler, and a curing agent, where the rubber component includes a block copolymer of polybutadiene and polyisoprene, and where the block copolymer has a cis content of at least 90%.