Comparison of Elastomers Vs. Silicone for Medical Devices

COMPARISON OF ELASTOMERS VS. SILICONE FOR MEDICAL DEVICES

Mark Hammond General Manager GW Silicones TOPICS OF DISCUSSION

•Review of Medical Elastomers •Medical Elastomers Processing •Liquid Silicone (LSR) vs High Consistency Silicone (HCR) •Liquid Silicone Tooling and Advantages •Multi-Material Molding

©2012 GW Plastics. All Rights Reserved. Proprietary & Confidential. GW PLASTICS OVERVIEW • Founded in 1955 • Financially strong, privately held company • Fortune 500® customer profile • Precision injection molding core competency • Thermoplastics and Liquid Silicone Rubber (LSR) • Focus on healthcare contract manufacturing • Clean room molding and assembly • Internal tooling and validation capability in the United States and China • RJG certified mold validation center • Highly standardized, fully automated facilities • Global quality systems – ISO 9001, ISO 13485, ISO 14001 • FDA registered

• Rubber is considered an elastic solid or a highly viscous fluid • The polymeric chains are long and flexible resulting in an entangled mass of chains which are chemically attached • When deformation occurs these tangled chains uncoil and then recoil when the force is removed so this gives rubber it’s “elastic” properties

• The long flexible polymeric chains of rubber when heated react with the vulcanizing agent –Sulfur or Peroxide catalyst for traditional elastomers –Platinum catalyst for Liquid Silicone • The vulcanizing agents facilitate the chemical crosslinking of the polymeric chains • These chains become permanently set in the presence of heat and do not soften in the presence of subsequent heating • Rubber is a “Thermoset” material

• Nitrile (Buna-N) –Resistance to oils with good balance of properties • Medical EPDM –Good resistance to acids and solvents • Butyl –Excellent low permeability to gases • Polyisoprene (synthetic natural rubber) –Excellent tear resistance

•Once set a thermoplastic material will soften when heated (and eventually liquefy) and harden when cooled. •This process is reversible and repeatable. •This allows for recycling and reusing molded materials which is a large advantage for thermoplastic materials. •Thermoset materials will not degrade with temperature so once a product is molded it cannot be easily converted back to a base material for re-processing.

• It’s a copolymer containing both thermoplastic and thermoset materials. • Fully cured thermoset particles are dispersed throughout a continuous thermoplastic matrix. • End result is a flexible material that is processed as a thermoplastic material. • Has limitations for flexibility and resistance to compression set especially at high and low temperature. • Lots of development from the material manufacturers to increase engineering properties of flexible plastic materials

• Material prepared in pre-weighed slugs and placed in each cavity. • Plates are brought together under tonnage compressing material.

• Pre-weighed slug of material is placed in “pot.” • Plates are pressed together transferring material through gates into cavity.

• Continuous rubber strip is pulled into screw of molding machine by screw rotation. • Normal injection molding cycle.

• Chemically inert, odorless, tasteless, and stainless; • Bacterial resistant and easy to clean and sterilize; • Biocompatible and short/long-term implantable; • Easily colored or 3rd stream additives possible; • Temperature flexible – 140°F to 600°F; • Fatigue and compression set resistant; • Chemical resistant; • High Elongation 100 - 900%; • Can have insulating or conductive electrical characteristics.

Source: The Freedonia Group Inc. • Medical was the fastest growing end market for silicones from 2001 to 2011 as a percentage. • Continued strong and steady growth in medical products shipments will drive advances in silicone demand • Silicones % growth will outpace medical products overall, taking share from competitive materials such as conventional rubber and PVC.

•Quicker cure times because of platinum cure system. •Off-the-shelf materials commercially available to anyone. •Material consistency. •Consistent raw material pricing. •Ease of processing for fabricator. –Ability to mold flashless and automatic using good molds. •Ease of overmolding plastic materials using self adhesive grades. •Liquid Silicone is easily colored •3rd stream additives such as anti microbial agents or “self lube”

•Higher degree of air permeation vs some elastomers. •High co-efficient of friction and surface tension.

•It’s a unique material relative to plastics. •It requires special equipment and expertise to be properly executed. •Anyone can “buy” their way into LSR molding but keeping molds running and executing as intended for the long run requires dedication and commitment from the organization.

©2012 GW Plastics. All Rights Reserved. Proprietary & Confidential. MULTI-MATERIAL MOLDING Why 2-Shot Liquid Silicone Rubber (LSR)? •Because it is possible – complex molded parts with finer detail and tighter tolerances. • Efficiency – eliminates adhesives and post-assembly operations. • Quality – Minimal part handling reduces contamination potential. • Cost – Process flow simplification. • Engineering Properties – Unique material combinations for more design and performance options.

©2012 GW Plastics. All Rights Reserved. Proprietary & Confidential. MULTI-MATERIAL MOLDING DESIGN CONSIDERATIONS •Thermal resistance of plastic substrate. •Chemical or mechanical bond of silicone to substrate. •Shrink and expansion of plastic substrate. •Method of part transfer from plastic to silicone cavity.

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•Liquid silicone is not a direct replacement for all elastomers in all applications. •Liquid silicone can offer pricing and quality advantages for OEM’s. •You should work with experienced silicone molders because of the skill set required for molding silicone. •TPE’s can work for specific applications but don’t try to “force it”. •Silicone pricing can be competitive with TPE if executed properly. •Look at new materials available on the market and don’t always use existing qualified materials