TPU Outsole Viscosity Control for Adhesive-Free eTPU Bonding

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Solution Overview

Problem

The conventional manufacture of shoe soles, particularly those involving expanded thermoplastic polyurethane (eTPU) particles, faces challenges in bonding with rubber outsoles without using adhesives, leading to unsatisfactory products due to melting, deformation, or bleeding of the TPU outsole material.

Innovation Solution

A method involving loading a pre-manufactured TPU article with an additive to increase viscosity or undergoing an annealing process, combined with loading eTPU particles into a mold and connecting them using an interconnecting medium like pressurized steam, to prevent undesirable deformation during molding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a TPU outsole is molded together with expanded TPU particles using steam or other energy transferring media, then adhesive-free bonding is achieved, but the TPU outsole material melts, deforms and bleeds leading to unsatisfactory products

Engineering Contradiction:

Improveadhesive-free bondingVSAvoidoutsole deformation

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by modifying the TPU outsole material properties through additives that increase viscosity or through annealing treatment that raises the melting onset temperature. These parameter changes allow the outsole to withstand the thermal energy of steam molding without melting or deforming, while still enabling bonding with eTPU particles.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs preliminary action by performing annealing treatment on the TPU outsole before the molding process, or by pre-incorporating viscosity-increasing additives into the outsole material. This preliminary preparation ensures the outsole has the necessary thermal stability before encountering the energy transferring media during bonding.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If adhesives are used to bond eTPU particle midsoles to rubber outsoles, then bonding is achieved, but environmental and worker health hazards increase due to solvents or other substances in adhesives

Engineering Contradiction:

ImprovebondingVSAvoidenvironmental and health hazards

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the chemical bonding mechanism of adhesives with a physical/thermal bonding mechanism using steam or other energy transferring media. This substitution eliminates the need for harmful adhesive substances while achieving reliable bonding between the eTPU particles and the outsole through controlled melting and fusion.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent enables the materials themselves to perform the bonding function without external adhesives. The eTPU particles and TPU outsole bond through their own material properties when exposed to energy transferring media, with the outsole material providing both the bonding interface and the structural integrity.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If the TPU outsole material viscosity is increased through additives or annealing, then melting and deformation during molding are prevented, but manufacturing process complexity increases

Engineering Contradiction:

Improveoutsole structure definitionVSAvoidmaterial processing steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent modifies fundamental material parameters (viscosity and melting temperature) of the TPU outsole through additives or annealing. These parameter changes are integrated into the material formulation or pre-processing stages, allowing the standard molding process to proceed without additional complexity while achieving the desired structural definition.

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

This approach effectively prevents melting and deformation of the TPU outsole, allowing for the production of high-quality shoe soles with well-defined structures and improved bonding between eTPU particles and TPU outsoles, reducing environmental and health hazards associated with adhesive use.

Implementation Method 1

connecting the particles with each other and to the pre-manufactured TPU article by providing an interconnecting medium

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

a material comprising an additive to increase the viscosity

Methodology Applied

Scientific EffectViscosity increase:

Implementation Method 3

a material which has been annealed

Methodology Applied

Scientific EffectAnnealing: Annealing

Data Source

PatentUS11964445B2Method for the manufacture of a shoe sole, shoe sole, and shoe with pre-manufactured TPU article

Publication Date: 2024.04.23 ADIDAS AG

AI summary

Described are a method for the manufacture of a shoe sole, the sole manufactured by the method, and a shoe including the sole. The method includes loading a pre-manufactured article comprising thermoplastic polyurethane (TPU) material into a mold; loading pellets of an expanded thermoplastic polyurethane (eTPU) material into said mold; and connecting the pellets with each other and to the pre-manufactured TPU article by providing an interconnecting medium, wherein the material of the pre-manufactured TPU article either comprises an additive to increase the viscosity of the material of the pre-manufactured TPU article, or has been annealed.