Isobutylene Elastomer Blends for Durable Tire Innerliners

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Solution Overview

Problem

Halogenated butyl rubbers used for tire innerliners face limitations in aged property retention, aged hardening, and flex fatigue, necessitating the improvement of their physical properties.

Innovation Solution

A composition comprising halobutyl rubber blended with a C4-C7 isoolefin, non-halogenated alkylstyrene, and halogenated alkylstyrene, where the non-halogenated and halogenated alkylstyrenes cumulatively constitute 3 wt% to 15 wt% of the elastomer composition, and the halogenated alkylstyrene is present at 0.1 mol% to 2 mol% relative to the non-halogenated alkylstyrene, enhancing the properties of the resulting elastomer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pure halogenated butyl rubber is used for innerliners, then air retention is improved, but aged property retention and flex fatigue resistance deteriorate

Engineering Contradiction:

Improveair retentionVSAvoidaged property retention

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent applies composite materials by blending halogenated butyl rubber with at least one other butyl rubber component having dissimilar microstructure. This creates a multi-phase composite system where the halogenated component provides air retention while the dissimilar microstructure component improves aged property retention and flex fatigue resistance, resolving the contradiction between these properties.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by introducing components with dissimilar microstructures into the halogenated butyl rubber matrix. The different microstructural regions provide localized functional improvements - the halogenated regions maintain air retention while the dissimilar microstructure regions enhance durability and aging resistance, allowing both properties to coexist.

Inventive Principle:

Principle #3Local quality

2Strength

If halogenated butyl rubber is used for innerliners, then adhesion behavior is improved, but flex fatigue resistance deteriorates

Engineering Contradiction:

Improveadhesion behaviorVSAvoidflex fatigue resistance

Core Design Contradiction:

StrengthVSDuration of action of moving object

Solution Approach 1:

The patent uses composite materials by combining halogenated butyl rubber (providing adhesion) with other butyl rubber components of dissimilar microstructure (providing flex fatigue resistance). This composite approach allows the adhesion benefits of halogenation to be retained while the microstructural differences mitigate flex fatigue deterioration.

Inventive Principle:

Principle #40Composite materials

3Reliability

If halogenated butyl rubber is used for innerliners, then impermeability to air and water is improved, but aged hardening increases

Engineering Contradiction:

Improveimpermeability to air and waterVSAvoidaged hardening

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies composite materials by blending halogenated butyl rubber (providing impermeability) with other butyl rubber components of dissimilar microstructure (mitigating aged hardening). The composite system maintains the barrier properties while the microstructural differences reduce the tendency toward excessive hardening during aging.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12252563B2Isobutylene-containing compositions and articles made thereof

Publication Date: 2025.03.18 EXXONMOBIL ENG & TECH CO

AI summary

An elastomer composition can comprise a C4 to C7 isoolefin; a non-halogenated alkylstyrene; a halogenated alkylstyrene; and optionally a diolefin, wherein the C4 to C7 isoolefin is not the same as the diolefin. Optionally, the elastomer composition can be blended with a butyl rubber and/or a halobutyl rubber. Such blends that also comprise additives may be suitable for producing tire components such as innerliners.