Transparent Rubber Shoe Sole Composition Yellowing Stability

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Solution Overview

Problem

Conventional transparent rubber compositions for shoe soles suffer from unsatisfactory transparency, high cost, and yellowing issues, particularly at high temperatures and during storage, while also lacking adequate wear resistance and maintaining tensile strength and hardness.

Innovation Solution

A rubber composition incorporating a solution polymerized styrene butadiene rubber (SBR) and styrene butadiene styrene (SBS) thermoplastic rubber with a total styrene content of at least 35% by weight, along with a controlled amount of crosslinking agent, silane coupling agent, and silica, to enhance transparency, wear resistance, and yellowing stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional transparent rubber compositions are used for shoe soles, then transparency is achieved, but yellowing occurs during storage and at high temperatures

Engineering Contradiction:
ImprovetransparencyVSAvoidyellowing stability
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters by specifying a polymer blend containing 70-90 parts by weight isoprene rubber, 5-30 parts by weight high-cis butadiene rubber, and 5-30 parts by weight solution polymerized styrene butadiene rubber, along with specific antioxidant packages (mixed phenolic antioxidants and mixed phosphite antioxidants) to achieve both transparency and yellowing stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite rubber composition by blending multiple rubber types (isoprene rubber, high-cis butadiene rubber, solution polymerized styrene butadiene rubber) with specific additives (fumed silica, organic peroxides, antioxidants) to achieve synergistic effects that simultaneously provide transparency, wear resistance, and yellowing stability

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If conventional transparent rubber compositions are used, then cost is reduced, but wear resistance is insufficient

Engineering Contradiction:
ImprovecostVSAvoidwear resistance
Core Design Contradiction:
Quantity of substanceVSStrength

Solution Approach 1:

The patent develops a composite material system combining isoprene rubber, high-cis butadiene rubber, and solution polymerized styrene butadiene rubber with fumed silica and crosslinking agents to achieve both cost-effectiveness and superior wear resistance through synergistic interactions among components

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the compositional parameters including the weight ratios of different rubbers, silica content (1-5 parts by weight based on total rubber), and crosslinking agent content to achieve the desired balance between wear resistance and cost

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If conventional transparent rubber compositions are used, then transparency is achieved, but yellowing occurs during shoe making and distribution

Engineering Contradiction:
ImprovetransparencyVSAvoidstorage stability
Core Design Contradiction:
Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent incorporates antioxidant packages (mixed phenolic antioxidants and mixed phosphite antioxidants) and crosslinking agents in advance during composition formulation to prevent yellowing during subsequent storage and processing operations, addressing the degradation issue before it occurs

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent modifies the chemical composition by specifying precise ranges for antioxidants, crosslinking agents, and rubber blend ratios to enhance the stability parameter, ensuring the composition resists yellowing during extended storage periods and high-temperature processing

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 composition achieves superior yellowing stability at both high and room temperatures, excellent transparency, and improved wear resistance while maintaining tensile strength and hardness, making it suitable for shoe sole production.

Implementation Method 1

a crosslinking agent

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

a silane coupling agent

Methodology Applied
Scientific EffectSilane coupling: Chemical Bonding

Data Source

PatentUS11118037B2Rubber composition for shoe sole and molded article comprising the same
Publication Date: 2021.09.14 FINE CHEM CO LTD

AI summary

Provided is a rubber composition for a shoe sole. The rubber composition includes: an elastic polymer including a styrene butadiene rubber (SBR) and a styrene butadiene styrene (SBS) thermoplastic rubber; and a crosslinking agent. The total styrene content of the elastic polymer is at least 35% by weight.