Rubber Composition Tackifier Molecular Weight Control

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Solution Overview

Problem

In rubber compositions for pneumatic tires, the addition of a large amount of tackifier leads to premature curing and cracking on the surface, disrupting the blooming of wax and enhancing ultraviolet ray-induced cracking, while also affecting adhesion to rolls.

Innovation Solution

A rubber composition comprising diene rubber, a tackifier with a weight average molecular weight of 1,500 to 2,500, and a wax with a specific carbon number distribution, where the wax content is lower than the tackifier, ensuring the wax blooms before the tackifier reaches the surface, thereby improving adhesion and suppressing cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a large amount of tackifier is added to improve adhesion to rolls, then adhesion to rolls is improved, but the tackifier moves to the rubber surface prior to wax and causes cracking

Engineering Contradiction:

Improveadhesion to rollsVSAvoidsurface cracking resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the molecular weight parameter of the tackifier resin to a specific range (1,500 to 2,500) to control its migration behavior. This parameter adjustment allows the tackifier to provide sufficient adhesion to rolls while preventing premature migration to the rubber surface that would cause cracking.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system combining specifically selected tackifier resin (with controlled molecular weight) and wax in defined proportions. This composite approach allows the tackifier and wax to work synergistically, where the wax can bloom on the surface to prevent cracking while the tackifier provides adhesion without premature migration.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If a large amount of tackifier is added, then adhesion to rolls is improved, but blooming of wax is disturbed and ultraviolet ray-induced cracking accelerates

Engineering Contradiction:

Improveadhesion to rollsVSAvoidultraviolet ray cracking

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent adjusts the molecular weight parameter of the tackifier to control its migration rate and interaction with wax. By setting Mw in the range of 1,500 to 2,500, the tackifier maintains adhesion performance while allowing wax to bloom properly on the surface, thereby preventing ultraviolet ray-induced cracking.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The wax acts as an intermediary substance between the tackifier and the external environment (ultraviolet rays). The patent ensures proper wax blooming by controlling tackifier properties, allowing the wax to form a protective film on the rubber surface that shields against ultraviolet radiation while the tackifier provides underlying adhesion.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If wax content is increased to prevent cracking, then ozone resistance is improved, but adhesion to rolls deteriorates

Engineering Contradiction:

Improveozone resistanceVSAvoidadhesion to rolls

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent formulates a composite system with optimized ratios of tackifier resin and wax. This composite approach allows the wax to provide ozone resistance through surface blooming while the tackifier resin provides adhesion to rolls, achieving both functions simultaneously without compromising either property.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the molecular weight parameter of the tackifier to optimize the balance between adhesion and wax blooming. This parameter adjustment enables the use of adequate wax content for ozone protection while maintaining strong adhesion to rolls through the specially selected tackifier properties.

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 solution effectively prevents cracking from ultraviolet rays and enhances adhesion to rolls while maintaining ozone resistance and appearance quality, even with a high tackifier content.

Implementation Method 1

The wax blooms on the surface of a rubber after vulcanization to form a coating film of a wax on the surface of a rubber

Methodology Applied

Scientific EffectBlooming:

Implementation Method 2

the tackifier moves to the surface of a rubber prior to a wax and cures thereon

Methodology Applied

Scientific EffectMigration:

Implementation Method 3

the tackifier moves to the surface of a rubber prior to a wax and cures thereon

Methodology Applied

Scientific EffectCuring:

Data Source

PatentUS9796836B2Rubber composition and pneumatic tire

Publication Date: 2017.10.24 TOYO TIRE CORP

AI summary

A rubber composition comprising a diene rubber, a tackifier comprising a resin having a weight average molecular weight of from 1,500 to 2,500, and a wax is disclosed. The wax contains from 20.0 to 40.0 mass % of a linear saturated hydrocarbon having from 25 to 30 carbon atoms, from 8.0 to 18.0 mass % of a linear saturated hydrocarbon having from 35 to 40 carbon atoms, and from 1.0 to 6.0 mass % of a linear saturated hydrocarbon having 45 or more carbon atoms. The amount of the tackifier added is larger than the amount of the wax added.