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Chris Lines Managing Director Dyne Technology Ltd

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Solving the Problems of Adhesion in Medical Device Manufacture © Dyne Technology 2013

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© Dyne Technology 2013

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1. What are the ideal surface properties needed to ensure optimum adhesion is achieved? 2. Why is achieving good adhesion to commonly used plastics like Polyethylene, Polypropylene just so difficult? 3. How do we improve adhesion? 3 Questions © Dyne Technology 2013

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What are the ideal surface properties needed to ensure optimum adhesion is achieved? Question 1 © Dyne Technology 2013

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© Dyne Technology 2013 Rough Wetting Etched Clean Chemically Attractive Oil free Neutral Polar Active Non-Porous Porous Abraded Smooth Ideal surface to bond to is……???? Scratched Flat Absorbent Dry

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© Dyne Technology 2013 Ideal Surface Clean Dry Dust Free Smooth Non- Porus Wettable Polar Ideal surface to bond to is……

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© Dyne Technology 2013

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Why is achieving good adhesion to commonly used plastics like Polyethylene, Polypropylene just so difficult? Question 2 © Dyne Technology 2013

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© Dyne Technology 2012

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Ideal Surface Clean Dry Dust Free Smooth Non- Porus Wettable Polar Ideal surface to bond to is…… © Dyne Technology 2013

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Ideal Surface Clean Dry Dust Free Smooth Non- Porus Wettable Polar Ideal surface to bond to is…… © Dyne Technology 2013

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© Dyne Technology 2013 Surface wetting Non wetting Wetting

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Surface Energy, Surface Tension & Wetting Low surface energy material Liquid does not “wet” the surface High surface energy material Liquid “wets” the surface © Dyne Technology 2013

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Measuring Surface Energy – Contact angle Contact angle of < 90º denotes a High Surface Energy Liquid wets the surface. Contact angle of > 90º denotes a Low Surface Energy Liquid does not wet the surface. Surface energy of the solid material can be calculated if the contact angles are measured using at least two different liquids with known properties. © Dyne Technology 2013

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Typical surface energy levels (untreated material) PTFE 18 – 20 mN/m (Dynes/cm²) PP 29 – 32 mN/m PE 30 – 33 mN/m PA 33 – 46 mN/m ABS 34 – 42 mN/m PVC 35 – 42 mN/m PC 43 – 46 mN/m Surface Energy - Typical Material Values Additives tend to lower the Surface Energy of materials © Dyne Technology 2013

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Surface Energy – Polar and Dispersive 0 10 20 30 40 50 60 70 80 PTFE - untreated PP - untreated PE - untreated ABS - untreated PA6 - untreated Polar component Dispersive component For illustration only – materials can vary widely mN/m (Dynes/cm) © Dyne Technology 2013

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© Dyne Technology 2013

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How do we improve adhesion? Question 3 © Dyne Technology 2013

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© Dyne Technology 2012 Needle hubs

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Needle Pull out force (N) Component: 1ml barrel Barrel material: Cyclo Olefin Polymer (COP) Adhesive: UV cured Adhesion test: Zwick / Roell – pull test © Dyne Technology 2013

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Typically the Surface Energy of the substrate will need to exceed the Surface Tension of the ink, coating or adhesive by at least 10 - 15 Dynes/cm² (mN/m). Surface Energy Required © Dyne Technology 2013

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 Typical required treatment levels: Solvent based printing 36 to 42 Dynes/cm² Water based inks 40 to 46 Dynes/cm² UV inks 40 to 54 Dynes/cm² Laminating and coating 50 + Dynes/cm² Solvent based paints 38 to 52 Dynes/cm² Water based paints 46 to 60 Dynes/cm² Surface Energy - Typical Treatment Levels  Surface energy is critically important to many bonding, printing, coating and converting operations. © Dyne Technology 2013

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Surface Energy - Polarity A material with low polar energy will not strongly attract inks, coatings or adhesives to its surface. Somewhat polar materials include ABS and Nylon (PA6), the properties of these can be improved by surface treatment. Non-Polar materials include Teflon, Polypropylene, Polyethylene and often need surface treatment before adhesion will occur! © Dyne Technology 2013

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Surface Energy – Polar and Dispersive (After Treatment) 0 10 20 30 40 50 60 70 80 Polar component Dispersive component For illustration only – materials can vary widely mN/m (Dynes/cm) © Dyne Technology 2013

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Surface Treatment Choices Chemical: Primers, Etching Corona: High Frequency, Low Frequency Plasma: Vacuum, Atmospheric, Flame © Dyne Technology 2013

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Corona, Plasma what’s the difference? Some people use the term ”Plasma” as a single term for any kind of electrically powered discharge. Plasma has become a buzz word! The difference between Corona & Plasma is simple: © Dyne Technology 2013

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Corona, Plasma what’s the difference? Plasma has little or no high voltage potential present in the discharge. It is simply an ionised gas. Corona has a high voltage potential present in the discharge. You can see the discharge filliments. © Dyne Technology 2013

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Corona Discharge © Dyne Technology 2013

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 A visible electrical discharge which occurs when a high voltage (5kV or more) is applied to a pointed or small diameter electrode in proximity to an electrical ground.  The resulting electrical discharge is known as a “Corona Discharge”  This corona discharge will cause partial ionization of the surrounding atmosphere and can be used for surface modification. Corona, what is it? © Dyne Technology 2013

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Vacuum Plasma Treating © Dyne Technology 2013

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Plasma is loosely described as an electrically neutral medium of positive and negative particles or as an “ionised gas”. “Ionised” refers to the presence of one or more free electrons which are not bound to an atom or molecule. Plasma is considered to be the 4th state of matter after solid, liquid and gas. Plasma, what is it? © Dyne Technology 2013

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 Using a vacuum pump most of the air is removed from a sealed chamber. Vacuum Plasma, how is it made?  When the chamber pressure reaches the required level the remaining air is subjected to a strong electrical field that ionises most of its atoms.  The resulting super ionised air occupies the chamber for a pre-determined time and can be used for surface modification. © Dyne Technology 2013

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Plasma Chamber Access Door Typical 2 tray unit shown. Actual number and size of trays to be selected by customer Plasma Chamber Control Panel Vacuum Plasma Treating – Typical unit © Dyne Technology 2013

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Vacuum Plasma Treating – Laboratory unit © Dyne Technology 2013

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Load parts Activate process Plasma treating Unload parts Vacuum Plasma – machine operation © Dyne Technology 2013

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Vacuum Plasma Treating of Catheters © Dyne Technology 2013

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Atmospheric Plasma © Dyne Technology 2013

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 Gas (usually compressed air) is passed through a cylinder and nozzle assembly. Atmospheric Plasma, what is it?  As the air passes through the cylinder it is subjected to a strong electrical field that ionises most of its atoms.  The resulting super ionised air is ejected through the nozzle tip and can be used for surface modification. © Dyne Technology 2013

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Plasma Treating Theory – Surface Activation Before Plasma Treating Non polar, non wetting surface Oxygen activated, polar and wettable surface After Plasma Treating Oxygen During Plasma Treating © Dyne Technology 2013

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Treatment of Injection Mouldings Improve adhesion and quality of bonding, coating and printing processes. © Dyne Technology 2013

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Corona Treatment of Catheter products Improve adhesion and quality of bonding and coating processes. © Dyne Technology 2013

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Corona Treatment of Ostomy Products Improve adhesion and quality of bonding and printing processes. © Dyne Technology 2013

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Corona Treatment of Culture Flasks Improve performance and quality of coating and wetting processes. © Dyne Technology 2013

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Remember this?....... Component: 1ml barrel Barrel material: Cyclo Olefin Polymer (COP) Adhesive: UV cured Adhesion test: Zwick / Roell – pull test © Dyne Technology 2013

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PLASMA TREATED BARRELS Component: 1ml barrel Barrel material: Cyclo Olefin Polymer (COP) Adhesive: UV cured Adhesion test: Zwick / Roell – pull test UNTREATED BARRELS The Problem of Adhesion - Solved! © Dyne Technology 2013

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Solving the Problems of Adhesion © Dyne Technology 2013