Metal-Particle Plastic for Orthopedic Skin Patches

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Solution Overview

Problem

Plastic materials used in medical and orthopedic applications discolor due to UV radiation and contact with sweat, leading to an unsightly appearance, and increasing pigment content to counteract this often compromises mechanical properties, which are crucial for these applications.

Innovation Solution

Incorporating finely divided metal particles, such as aluminum or its alloys, magnesium, bronze, titanium, and platinum, into plastic materials, along with silver as an antibacterial agent, to minimize discoloration while maintaining material properties and aesthetics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If pigment content is increased to counteract discoloration, then discoloration is concealed, but mechanical properties deteriorate

Engineering Contradiction:
Improvediscoloration concealmentVSAvoidmechanical properties
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent introduces metal particles as an intermediary substance that mediates between the conflicting requirements of discoloration concealment and mechanical property preservation. The metal particles provide optical coverage against discoloration while maintaining material integrity, unlike pigments which compromise mechanical properties when used in high concentrations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the material composition parameter by replacing organic pigments with inorganic metal particles. This parameter change allows achieving discoloration concealment through different physical mechanisms (metallic reflection vs. pigment absorption) that do not adversely affect mechanical properties.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If silver is added for antibacterial effect, then antibacterial protection is improved, but discoloration increases due to silver sulfide formation

Engineering Contradiction:
Improveantibacterial effectivenessVSAvoidaesthetic appearance
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent converts the harmful effect of silver sulfide formation (black discoloration) into a beneficial aesthetic feature by selecting dark-colored metal particles that make the discoloration imperceptible. The harm of silver oxidation is transformed into an acceptable visual outcome through strategic color matching.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent employs color change strategy by choosing metal particles with specific colors (black, dark gray, bronze) that mask the discoloration caused by silver sulfide formation. This color selection makes the antibacterial silver content visually acceptable or even aesthetically pleasing.

Inventive Principle:
Principle #32Color changes

3Ease of manufacture

If light-colored plastic is used for aesthetics, then visual appeal is improved, but discoloration becomes more noticeable

Engineering Contradiction:
Improvevisual appealVSAvoiddiscoloration visibility
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces metal particles as an intermediary that protects light-colored plastics from discoloration visibility. The metal particles provide optical coverage that masks yellowing and discoloration while preserving the light color aesthetic, acting as a protective layer between the plastic and environmental degradation.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 allows for effective concealment of discoloration with significantly reduced pigment content, preserving the mechanical properties and visual appeal of the materials, even in moisture-permeable plastics, without compromising the antibacterial effectiveness of silver.

Implementation Method 1

the colored plastic part becomes darker over time due to the absorption of light from both effects, the intended effect of the color pigment and the unwanted discoloration

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

The antibacterial effect of silver is attributed to the silver ions, which are easily formed in contact with the skin through skin fluids and perspiration. During use, the silver partially oxidizes.

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentEP2391674B1Use of finely dispersed metal particles in a material, a skin patch and an orthopedic article
Publication Date: 2016.01.06 OTTO BOCK HEALTHCARE GMBH

AI summary

The invention relates to a material which is provided for use in direct contact with the skin of a user and which contains a percentage in silver that is finely dispersed in said material. The material is provided with a content in another metal that is finely dispersed in the material in addition to the silver content. The metals of the group including aluminum, magnesium, zinc, bronze, titanium and platinum are suitable either individually or in combination and in amounts between 0.1 and 1% by weight. The use of the metal particles is also suitable to conceal discolorations in a pigmented or dyed synthetic material when the material is used in air or on the skin. The metal particles do not impair the properties of the material. The material can be used to produce skin patches of any kind, especially for use in orthopedics.