Oliver-Tolas Healthcare Packaging A leading provider of sterile barrier packaging for medical device and pharmaceutical customers around the world Pouching Die-cutting Cleanroom manufacturing Printing Slitting Hand assembly Adhesive formulation Xhale hot melt SealScience - water based Osurance (zone coated) water based and hot melt Pouches Lids Rollstock
HealthPack Europe A Comparative Analysis of Medical Packaging Adhesive Technologies Abstract: A comparative analysis of medical device packaging adhesive technologies will be presented: hot melt, water-based, and resin systems. Each technology s materials and processes will be described. Representative data on adhesive transfer, sealability, peel strength, porosity, and creep resistance will be given, followed by a discussion of advantages and disadvantages for each technology. Richard L. Brady, PhD Technology Manager December 4, 2012
Introduction Heat Seal Polymers Heat Seal Mechanisms Review Materials and Processes Water Based Adhesive Coating Hot Melt Coating Resin Based Peelables Comparative Data Advantages and Disadvantages Summary Outline
Introduction - Heat Seal Polymers Heat Seal Polymers Thermoplastics (vs. Thermosets) High molecular weight No residual monomer safe No chemical reaction not curing No shelf life issues Fast seal - melt/flow
Introduction - Heat Seal Polymers Thermoplastics Semi-crystalline Crystalline and amorphous regions Polyethylene and many PE copolymers Ethylene - vinyl acetate (EVA) Flow above melting point Amorphous No crystallinity VAE s (vinyl acetate - ethylene copolymers) Flow above glass transition temperature (T g )
Semi-Crystalline
Amorphous
Introduction - Heat Seal Mechanisms Adhesive Peel Separates between the interface of the two webs heat sealed together
Heat Seal Mechanisms Cohesive Peel The adhesive layer splits when peeled
Frequently Asked Question What do you mean by cohesive strength? Cohesive strength is the bond of the adhesive to itself as opposed to adhesive strength which is the bond of the adhesive to another material. Peelable adhesives are often formulated to be adhesively strong (good bond to Tyvek and PETG/EVA etc.), but to fail cohesively.
Water Based Adhesive Coating Adhesive ingredients are blended together in a large attritor that is charged with ceramic media. (typical batch time 60 90 min. @ 32% - 40% solids) High molecular weight polymers such as EVA and VAE s Resins for specific substrate adhesion Waxes for anti-blocking and split control Some materials are specially blended for high performance applications. Blend / Coat Cool - Dried Hot
Ethylene Vinyl Acetate (EVA) Polymers
Resins
Waxes
Methods of Application Air knife Coat - Overall Coating Gravure Coat Overall or Zone Coated Silkscreen - Zone Coated Automatic Manual
Air Knife Process Fitz mill (to pre-grind resins and waxes) Attritor Supply Tanks Side tank and Coating Pan Air knife Oven Coating weight typically (3-11 lbs./ream)
Air Knife Process Characteristics Coating uniformity on various substrates smooth (film) or rough (Tyvek ) Consistent coat weight delivery throughout the run Coat weight easily changed for various products by adjusting air-knife pressure Aesthetic appeal smooth coating (non grit / non tacky) Ability to coat various substrates (film, paper, foil, Tyvek, non-wovens)
Zone Coating Methods Zone Coated Lids & Rollstock Adhesive is applied only to seal area Device is not in contact with adhesive Gravure and Print Process Sheet Fed Die Cut Materials
Gravure Coat and Print Process One reverse station for printing (eye mark) Multiple coating stations ( 4-8 lbs./ream ) Roll to roll for FFS applications
Materials and Processes - Hot Melt Coating Adhesive ingredients are blended together in an extruder and heated tank (between 3 and 8 components) Polymers (usually EVA) for strength Resins for adhesion to specific substrates Waxes for blocking resistance, viscosity control, split Additives for opacity, color, resistance to oxidation 100% solids. Liquid at 300 F.
Hot Melt Gravure Coating Technology Melt Coat Cool (quickly) Coating temperatures are 250 325 F Some substrates (Tyvek ) start to melt at 265 F Machine speeds are 250 to 350 feet per min. Exposure to heat is kept to a minimum (0.04 seconds maximum) Many different patterns are possible Tooling is a key component in controlling coating weight (from 3 to 50 lbs./3000 sq. ft.)
Gravure Coating Process (Hot Melt Coating)
Gravure Coating Technology Characteristics Gravure coating allows for discrete dot (pattern) placement Adhesive coating is limited to the engraved pattern Other areas of the substrate are left open for porosity Coating weights of 3 to 50 lbs./3msf possible Coating weights can be controlled by tooling Normal weights of 10-16# Patterns can be used for texture as well as functionality Hot melt gravure does not require a drying operation Hot melt coating equipment is usually smaller than comparable water-based coating equipment
Variations in Dot Coating (35% coverage) 30 Sec. Gurley (50% dot coverage) 30 sec. Gurley (60% dot coverage) 33 sec. Gurley (smoothed) 65 sec. Gurley
Variations in Pattern Coating Honeycomb Pattern Grid Pattern
A Magnified View
Frequently Asked Questions How big are the dots? Approximately 0.00012 sq in or 0.076 sq mm. How many dots per inch? 65 x 65 = 4225 per square inch. 608,400 per square foot. 100 billion per 14,000 ft roll If you are blocking off 55% of the surface, why don t you lose 55% of the porosity? Air flow will always seek the easiest path, so it will go around barriers (like dots).
Peelable Films Early films based on polybutylene-polyolefin blend technology The incompatibility of the 2 polymers comprising the sealant layer lowers the cohesive strength and allows cohesive split Peelable sealants are incorporated into extruded films, generally by coextrusion; often then laminated (adhesive or extrusion lamination) to provide additional functionality Peelable structures also by extrusion coating
Sealant Film
Autoclave Sealant
Adhesive Transfer Sealablility Peel Strength Porosity Resistance to Creep Comparative Data
Adhesive Transfer
peak seal strength lb/in Sealability/Peel Strength Tyvek to Flexible Forming webs 2.5 2.0 1.5 1.0 0.5 0.0 230 240 250 260 270 Seal Temperature F hot melt coated Tyvek to EVA/Ionomer/EVA Waterbased coated Tyvek to EVA/ionomer/EVA Uncoated Tyvek to Sealant forming web
seconds Porosity Gurley Porosity for Pouches 125 100 75 50 25 0 35 55 29 Hot Melt Coated Tyvek Water-based Coated Tyvek Uncoated 1073B Tyvek
Time till seal failure (min) Resistance to Creep 37 High Temperature & Humidity Creep at 50 C & 60 C /96%RH under 200 gram load Sealed to PETG 120 90 60 30 0 Hot Melt coated Tyvek Water-Based coated Tyvek PET/Sealant Film 50 C 60 C
Advantages and Disadvantages Water Based Advantages White and consistent transfer Humidity creep resistance at 60C Versatility, ease of coating Disadvantages Porosity not as good as hot melt or uncoated
Advantages and Disadvantages Hot Melt Advantages Good porosity (partial coverage of dots) Low sealing Temperature Flat seal strength profile Disadvantages Creep resistance vs. water-based
Advantages and Disadvantages Sealant Film Advantages No coating process required Disadvantages Can be more sensitive to sealing parameter variation than coated materials narrower seal window Seal transfer not as consistent as coated materials can get stringing Tend to require longer dwell times for sealing so not as good for FFS
Summary The three main adhesive technologies for medical device packaging are hot melt coating, water-based coating, and resinbased systems. Hot melt coatings maintain porosity closer to the uncoated material than water-based coating. This is achieved by a dot coating. Hot melt coatings can utilize low seal temperatures and have flat seal curves. Coated systems tend to exhibit better seal transfer than peelable resin systems, with water-based coating giving the most distinct transfer. Water based coatings exhibit better creep resistance than the other two technologies.
Summary Water-based technology can be zone coated by both gravure and silk screen processes. Peelable resin systems tend to be more sensitive to sealing parameter variation,with higher activation temperatures. Peelable resin systems tend to require longer machine dwell times for sealing than coated systems, thus are better suited for platen systems vs. FFS.
Dispos-a-vent, DotCoat, ISOTECH Bag, LogoTint, Oliver-Tolas, Osurance, Ovantex, SealScience, VisiSeal, WaterMark and Xhale are trademarks or registered trademarks of Oliver-Tolas Healthcare Packaging. DuPont and Tyvek are trademarks or registered trademarks of DuPont.