Pressure Sensitive Adhesive Tapes for Sales and Marketing Professionals Tape University Basics May 12, 2009 Adhesives Larry K. Post North American Technical Services & Strategic Account Technology Manager Ashland, Inc. Dublin, OH

Larry K. Post More than 30 years in PSA tape industry Specializing in solution, emulsion and radiation cure PSA adhesives B.S. and M.S. in chemistry from Wright State University Graduate research on synthesis and polymer characterization of new polymerizable herbicide monomers Larry K. Post North American Technical Services & Strategic Account Technology Manager Ashland, Inc. Dublin, OH

Types of Adhesives Liquid Adhesives Solid Adhesives Calendered (Rubber) Hot Melt (Thermoplastic Elastomers) Reactive (Acrylic and Silicone) Radiation Cured Water Based (Rubber and Acrylics) Solvent (Acrylic, Rubber, and Silicone)

Common PSAs Natural Rubber Synthetic Rubber Acrylic Adhesives Silicone Adhesives

Rubber Based Adhesives Elastomer Natural and Synthetic Rubbers (Butyl, Styrene Butadiene, Polyisoprene, Thermoplastic Elastomers) Tackifiers Natural (Rosin, Rosin Salts and Esters) Synthetic Hydrocarbons(C5, C9, Polyterpenes) Fillers Clay, Calcium Carbonate, Talc and Silica Plasticizing Oil Polybutene Naphthenic Oils Anti-oxidants Cross Linking Agents Flame Retardants Colorants Deodorants

Performance Characteristics and Features Multi-component systems requires intensive processing Natural and synthetic components Applied as 100% solids and from solutions Cost effective Good tack and adhesion to a variety of surfaces including low surface energy surfaces Good shear strength Duct, and some Packaging and Masking Tapes are based on Natural Rubber

Performance Characteristic Shortcomings Fair Chemical, UV and Oxidation Resistance Poor Elevated Temperature Resistance Moderate Useful Life Time Requires Extensive Processing (except hot melt)

Rubber vs. Thermoplastic Rubber Adhesives Similarities Differences Natural rubber adhesives have higher operating temperatures Natural rubber can be chemically crosslinked vs. physical crosslinks for thermoplastic rubber Thermoplastic rubber adhesives melt Natural rubber adhesives require intensive mixing Tackifiers Anti-oxidants Fillers Oils Same formulating principles Can be coated as 100% solids or from solution

Natural Rubber Tackification 1400 1200 1000 800 600 400 200 Natural Rubber Tackification From Handbook of PSA Technology 3rd Edition, pg. 265, edited by Don Satas, Satas & Associates, Rhode Island © 1999. Fig. 13-3 Effect of resin concentration on peel adhesion (X), tack (*) and shear resistance (0) for hydrocarbon resin in natural rubber

Synthetic Adhesives Acrylic Adhesives Silicone Adhesives 2-Ethyl Hexyl Acrylate, Butyl Acrylate and co-monomers Cross Linker Silicone Adhesives Dimethyl and Diphenyl Dimethyl Silicones Catalyst (Platinum or Peroxide)

Acrylic PSA Features Colorless-excellent clarity Balanced shear, adhesion and tack Low Tg Excellent resistance to thermal and UV degradation Excellent aging characteristics Broad temperature performance range Good resistance to non-polar solvents Water resistant Non-corrosive Easily formulated Biocompatible (ISO 10993) Sterilizable (EtO & Radiation) chemistry

Solution Acrylics Good balance of properties; generally higher performance than emulsion acrylics Coater ready Mechanically stable Viscosity controlled by solvent & solids Newtonian rheology Solvent management UL foil tape, mounting tapes, and transfer tapes

Packaging tape largest application for emulsion acrylics Polymerized in water (surfactant needed) Good properties similar to solution acrylics but typically lower adhesion, tack and shear. Stabilize emulsion from biological attack Some sensitive to water Environmentally safe Less expensive than solution acrylics Packaging tape largest application for emulsion acrylics

Effect of Crosslinking and Molecular Weight on Mechanical Properties From Advances in Pressure Sensitive Adhesive Technology, Don Satas, p. 3, © 1989, Satas & Associates, RI.

Silicone Adhesives’ Features Wide temperature use range up to 500F Biocompatible (ISO 10993) Sterilizable (EtO and Radiation) Resistant to moisture, UV, oxidation, chemical and biological attack Excellent electrical insulation properties Adheres to difficult to bond to substrate such as polyimides and fluoropolymers Clean removability

Silicone Adhesives have…. Better resistance to moisture, microbes, UV, chemicals, and oxidation Broader temperature use range Lower adhesion and tack at room temperature, but better properties at temperature extremes More expensive …than acrylic and rubber based adhesives

Applications for Silicone PSAs Printed Circuit Board Mask Solder Mask Electrical Insulating Tapes Silicone to Silicone Bonding Applications (Splicing Tape) Low Friction Tape Plasma Spray Tape Medical Applications

MQ Silicate Tackifier Resin Silicone PSA Compositions MQ Silicate Tackifier Resin From T. Mitchell Dow Corning Presentation, February 2002

Properties of Adhesives Rubber Adhesives Acrylic & Silicone Adhesives Chemistry Molecular Weight Degree of Chain Entanglement Degree of Cross Linking Tg Chemistry Molecular Weight Rubber:Resin:Filler:Oil Ratio Degree of Cross linking Tg Physical properties and fitness for use are governed chemistry, molecular weight, crosslink density, and additives

Considerations for Adhesive Selection Environment Temperature of Application and Use Relative Humidity Exposure to Sunlight, Water, Chemicals Application Machine or Hand Applied Speed of unwind or liner removal Pressure of application Time for bond formation Functionality Surface (Chemistry, Texture and Cleanliness) Barrier Properties Removable residue free, repositionable or permanent Leachable Materials FDA compliant (skin and food) Regulatory compliant Material and Performance specifications Life Time Cost Chemistry and Process determine adhesive properties which combined drive COST!

Performance Comparison TACK and PEEL: Rubber>Acrylic>Silicone COHESIVE STRENGTH at ELEVATED TEMPERATURE: Silicone>Acrylic>Rubber STABILITY: Silicone>Acrylic>Rubber TEMPERATURE RANGE: Silicone>Acrylic>Rubber COST: Silicone>Acrylic>Rubber Convertibility Silicone>Acrylic>Rubber

How Things “Stack-Up” * High to low surface energy silicones, poor to low surface energy ethylenes J Johnston - Personal communication

How do you know which adhesive to use? Factors to Consider Surfaces Application Functional Properties Service Temperature Thermal Resistance Chemical Resistance Barrier Properties Durability Construction Cost The selection of the type of adhesive is determined by understanding the functional properties required, application technique and cost.