Injection-Molded Elastomer Composition for Precise Mold Surface Replication

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Solution Overview

Problem

Existing injection molded articles made from elastomer compositions often fail to accurately reflect the molding surface of the forming mold due to poor fluidity, leading to issues with appearance and precision in complex-shaped products like shoe parts.

Innovation Solution

The use of a specific elastomer composition comprising a blend of styrene-based thermoplastic elastomers with varying molecular weights and structures, including a first styrene-based thermoplastic elastomer with a mass average molecular weight of 300,000 or more and a second styrene-based thermoplastic elastomer with crystalline polyethylene blocks, enhances fluidity and surface reflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional elastomer composition is used for injection molding, then the material can be processed, but the fluidity is poor and the molding surface cannot be precisely reflected

Engineering Contradiction:

Improvesurface reflection precisionVSAvoidfluidity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent uses a composite elastomer composition containing multiple thermoplastic elastomers (styrene-based, polyolefin-based, and polyester-based) with different molecular weights and structures. This composite approach combines the advantages of each elastomer type to achieve both good fluidity for mold replication and adequate mechanical properties, resolving the contradiction between manufacturing precision and ease of manufacture.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent specifies precise compositional parameters including the types of thermoplastic elastomers, their molecular weights, and content ratios (e.g., styrene-based elastomer 30-70 parts, polyolefin-based elastomer 10-50 parts, polyester-based elastomer 5-30 parts). By optimizing these parameters, the composition achieves the right balance between fluidity for surface replication and processability.

Inventive Principle:

Principle #35Parameter changes

2Strength

If high molecular weight elastomer is used to improve strength, then the material strength increases, but the fluidity during injection molding deteriorates

Engineering Contradiction:

Improvematerial strengthVSAvoidfluidity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent divides the elastomer composition into multiple segments with different molecular weights and types. Instead of using a single high molecular weight elastomer, it combines multiple elastomers including those with lower molecular weights to maintain fluidity while incorporating higher molecular weight components for strength, thus resolving the contradiction between strength and fluidity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

By creating a composite system of multiple thermoplastic elastomers with varying molecular weights, the patent achieves a synergistic effect where lower molecular weight elastomers provide fluidity and higher molecular weight elastomers provide strength, simultaneously satisfying both requirements.

Inventive Principle:

Principle #40Composite materials

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

This composition allows for the production of injection molded articles with smooth, transparent surfaces that precisely replicate the molding surface, reducing the need for additional surface treatments and improving the appearance and production ease of shoe parts.

Implementation Method 1

injecting the elastomer composition in a heated and molten state into a cavity of a forming mold

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

injecting the elastomer composition in a heated and molten state into a cavity of a forming mold

Methodology Applied

Scientific EffectInjection: Injector

Implementation Method 3

allowing the elastomer composition filled in the cavity to cool and set

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS12552925B2Injection molded article and shoe

Publication Date: 2026.02.17 ASICS CORP

AI summary

Provided is an injection molded article composed of an elastomer composition including: a plurality of styrene-based thermoplastic elastomers that include a first styrene-based thermoplastic elastomer that is a block polymer having a mass average molecular weight of 300,000, and a second styrene-based thermoplastic elastomer that is a block polymer having a polyethylene block exhibiting crystallinity; and a plasticizer.