Flame-Treated Silicone-Polyurethane Bonding for Implants
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Solution Overview
Problem
The challenge lies in effectively bonding silicone-based materials to polyurethane components for long-term implantable medical devices, as silicone's low surface energy and polyurethane's instability under in-vivo conditions hinder strong adhesion, and existing methods like primers and glues fail to provide a durable bond.
Innovation Solution
The process involves flame treating the silicone surface to create oxides that react with isocyanate groups in polyurethane, forming a strong bond between the two materials, enhancing adhesion and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silicone surface is treated with primer or glue, then adhesive properties improve, but bond durability deteriorates under in-vivo conditions
Solution Approach 1:
The patent applies flame treatment to fundamentally change the surface parameters of silicone by introducing oxygen-containing functional groups and increasing surface energy. This transforms the silicone surface from low surface energy (poor adhesion) to high surface energy (good adhesion), enabling strong and durable bonds with polyurethane under in-vivo conditions without requiring primers or glues
Solution Approach 2:
The patent replaces mechanical/chemical bonding methods (primers, glues) with a physical surface modification method (flame treatment). The flame treatment creates a permanently modified surface layer with enhanced chemical reactivity, substituting the need for additional bonding agents and creating a more reliable direct bond between silicone and polyurethane
2Strength
If polyurethane is used for high abrasion resistance, then mechanical properties improve, but biostability deteriorates under in-vivo conditions
Solution Approach 1:
The patent creates a localized interface zone at the silicone-polyurethane bond where flame treatment generates a surface layer with enhanced properties. This local modification at the bonding interface provides both strong adhesion and improved biostability, allowing the polyurethane to maintain its abrasion resistance while the treated interface resists degradation under in-vivo conditions
3Ease of manufacture
If silicone surface energy is kept low for mould release, then ease of manufacture improves, but adhesive properties deteriorate
Solution Approach 1:
The patent applies flame treatment as a preliminary surface preparation step before bonding silicone to polyurethane. This preliminary action permanently modifies the silicone surface to high surface energy state, creating optimal adhesion conditions for subsequent bonding operations. The low surface energy property is temporarily used for mould release during manufacturing, then flame treatment is applied to enable strong bonding in the next manufacturing stage
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 method significantly improves the adhesive properties of silicone-polyurethane bonds, resulting in biostable, abrasion-resistant, and mechanically robust biomaterials suitable for long-term implantable medical devices.
Implementation Method 1
flame treating a surface of the silicone or silicone based material
Implementation Method 2
bonding the polyurethane to the flame treated surface of the silicone or silicone based material
Data Source
AI summary
The invention relates to a process for bonding a silicone or silicone based material to a polyurethane and use of the bonded silicone-polyurethane in the manufacture of biomaterials, devices, articles or implants, in particular long term implantable medical devices in the fields of cardiology, orthopedics, plastic surgery and gastroenterology. The process involves the steps of (a) flame treating a surface of the silicone or silicone based material and (b) bonding the polyurethane to the flame treated surface of the silicone or silicone based material.