Orthopedic Cushion Coating via Volatile Extraction and CVD
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Solution Overview
Problem
Existing methods fail to apply a uniform, thin, and effectively adherent friction-reducing coating to orthopedic cushions made of filled elastomers, elastomer gels, or polyurethane materials, leading to non-uniform deposition, adhesion issues, and premature wear.
Innovation Solution
A process involving pretreatment to extract volatile constituents from the surface of fully polymerized polyurethane cushions, followed by a nonpolar polymer coating application using chemical or physical gas-phase deposition, ensuring secure adhesion and maintaining mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a friction-reducing coating is applied to increase slip capability, then the slip capability is improved, but the coating layer thickness becomes relatively high and impairs the properties of the liner material
Solution Approach 1:
The patent changes the parameters of the coating process by using chemical vapor deposition (CVD) to deposit poly(para-xylylene) coating at controlled thicknesses of 1-10 micrometers. This parameter change enables thin, uniform coatings that provide slip capability without impairing the liner material properties, resolving the contradiction between slip capability and coating thickness control.
2Ease of manufacture
If known CVD or PVD coating processes are used on flexible polyurethanes and polyurethane gels, then coating is attempted, but the results show non-uniform deposition, variations in layer thickness, heterogeneity, cracking, and large areas of non-adhesion
Solution Approach 1:
The patent introduces a specific intermediary substance - poly(para-xylylene) deposited via CVD process - that acts as a mediator between the coating equipment and the flexible polyurethane substrate. This intermediary coating method provides uniform deposition and strong adhesion without the defects of direct coating approaches, resolving the contradiction between ease of manufacture and coating reliability.
3Ease of operation
If the coating is applied to provide slip capability, then the friction is reduced, but the coating may crack and show premature wear under severe mechanical loads
Solution Approach 1:
The patent employs a thin film coating of poly(para-xylylene) deposited by CVD process. This thin film structure is flexible enough to accommodate the mechanical deformation of the liner during use while maintaining coating integrity. The thin film provides slip capability and resists cracking and premature wear under severe mechanical loads, resolving the contradiction between slip capability and coating durability.
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 achieves a uniformly adherent, thin friction-reducing coating that enhances slip capability without impairing the cushion material's functionality, even under severe mechanical loads, and extends the lifespan of the orthopedic cushions.
Implementation Method 1
Said coating is applied by chemical vapor-phase deposition (CVD)
Implementation Method 2
the fully polymerized polyurethane cushion is subjected to at least one pretreatment step in which volatile constituents are extracted from the surface
Data Source
AI summary
The invention relates to an orthopedic cushion made from a filled elastomer or softened thermoplastics and can be provided with a thin friction-reducing coating made from a non-polar, non-hydrophilic slip-increasing polymer coating namely poly(para-xylene). According to the invention, the above can be achieved by means of a method in which the polymerized polyurethane cushion is subjected to at least one pretreatment step in which volatile components are removed to such an extent as to be able to be immediately coated.