Multiphase Vinyl Primer for Coiled Wires
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Solution Overview
Problem
Medical instruments, particularly guide wires and catheters, face challenges with high frictional resistance during insertion into body cavities, leading to difficulties in smooth operation and potential tissue trauma, with existing coatings either being too thick, lacking sufficient adhesion, or failing to maintain lubricity over time.
Innovation Solution
A coating system comprising a primer and a curable topcoat, where the primer is an aqueous multiphase vinyl polymer with a glass transition temperature range that provides excellent adhesion, elasticity, and intercoat adhesion, allowing for a lubricious, hydrophilic surface that reduces friction and maintains flexibility even when bent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If silicone oil or Teflon coating is applied to reduce friction, then frictional resistance decreases, but the coating fails to retain lubricity over time
Solution Approach 1:
The patent applies a composite coating system consisting of a polyurethane base layer combined with a hydrophilic lubricious topcoat layer. This composite structure integrates the adhesion and mechanical properties of polyurethane with the low-friction, lubricity-retaining properties of hydrophilic materials, solving the problem of silicone oil and Teflon coatings failing to maintain lubricity over time.
Solution Approach 2:
The patent modifies the surface properties by applying a hydrophilic topcoat that changes the surface energy and wettability parameters. This hydrophilic modification enables the surface to retain lubricity through water-based lubrication mechanisms, fundamentally changing how the surface maintains low friction compared to traditional hydrophobic coatings.
2Strength
If polyurethane coating is applied directly on metal surface, then adhesion improves, but the coating layer must be thick which diminishes the metal diameter
Solution Approach 1:
The patent segments the coating into two distinct functional layers: a thin polyurethane primer layer (0.5-5 microns) that provides adhesion to the metal substrate, and a hydrophilic topcoat layer that provides lubricity. This segmentation allows each layer to be optimized for its specific function with minimal thickness, preserving the metal wire diameter while achieving both adhesion and lubricity.
Solution Approach 2:
The patent applies different material properties to different locations in the coating structure. The polyurethane layer is applied locally at the metal-coating interface to provide adhesion, while the hydrophilic topcoat is applied at the outer surface to provide lubricity. This local differentiation of material properties allows thin layers to achieve multiple functions without compromising the metal diameter.
3Strength
If thick polyurethane layer is applied to ensure adequate performance, then cohesive forces improve, but the metal diameter is reduced and flexibility is compromised
Solution Approach 1:
The patent divides the coating system into a thin polyurethane adhesive layer and a hydrophilic lubricious topcoat layer. This segmentation eliminates the need for thick polyurethane layers, as the adhesive layer only needs to be sufficient for bonding (0.5-5 microns), while the topcoat provides the lubricity function. The result is a coating system that maintains flexibility and does not compromise metal diameter.
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 coating system effectively reduces frictional resistance, ensuring smooth insertion and operation of medical devices, while maintaining adhesion and wear resistance, making it suitable for use in cardiovascular and neurointerventional procedures.
Implementation Method 1
a primer coating composition... comprising a multiphase vinyl polymer... provides excellent adhesion
Implementation Method 2
a lubricious, hydrophilic surface... reduces friction
Data Source
AI summary
Disclosed is a method to provide a metal wire with a coating system comprising a primer and a topcoat, particularly a hydrophilic, lubricious topcoat. The method comprises applying directly onto the wire metal a primer coating composition, which is an aqueous coating composition comprising a multiphase vinyl polymer, the polymer comprising a first phase having a Tg in the range of from −20° C. to 40° C. and a hard phase having a Tg in the range of from 25° C. to 120° C. The primer has good adhesion to both the metal surface and the topcoat, and provides the eventual coating system with, inter alia, a good flexibility.