Film star
Medical applications for polyolefin films by Sunil Inamdar, Polyzen director of technology
Polyolefins in medical applicationsPolyolefins are used extensively in the medical industry due to relatively low cost and unique performance properties, including chemical resistance, inertness, and light weight. The two most common polyolefins, polyethylene (PE) and polypropylene (PP), are used in applications ranging from syringes to storage bags.A hallmark of polyolefins is their ease of melt processing. Polyolefins can be extruded, blow moulded, injection moulded, and thermoformed. However, bonding polyolefin components can be challenging. Adhesives and solvents are largely ineffective due to the outstanding chemical resistance of these polymers. While heat bonding is a preferred alternative, unique thermal characteristics of polyolefins can present challenges for precision welding of medical devices.
Film-based polyolefin constructionsMedical bags, protective sleeves, wound care, and numerous other applications have been constructed from polyolefin films for years. In recent times there has been increasing demand for polyolefin replacement of polyvinyl chloride (PVC) films due to concerns about toxicity and plasticizer leaching. Low density PE film does not require plasticisers to achieve comparable flexibility to PVC and is more economical than some ethylene vinyl acetate (EVA) or thermoplastic polyurethane (TPU) alternatives.Film-based medical constructions, such as bags or sleeves, require welding film. This is most commonly done using radio frequency (RF) thermal heating. Polyolefins can be more difficult to RF weld than PVC; however, multi-layer polyolefin films that incorporate polymers with improved welding performance have been used to overcome this limitation. New grades of polyolefins have also been developed in recent years, specifically to improve welding.The challenge of film welding polyolefins has been further complicated by medical device companies decreasing wall thicknesses in film-based constructions. Thinner walls reduce product weight which can improve functionality, handling and environmental impact when disposed. However, thinner walls require greater precision in welding to avoid overheating seams.Material selection, film thickness and weld quality are interrelated variables in these applications. It is not uncommon for development to include multiple iterations between materials and processes. Since early stage development requires evaluation of polymer candidates through the entire process of film extrusion and RF welding it is advantageous to have these processes in close proximity. This can speed development time and overall time to market by reducing time between iterations.
Comprehensive development partner modelIn today’s highly competitive medical marketplace, innovation and speed to market is essential to survival. Many medical companies are focusing on new product designs and are relying on outside vendors to provide material recommendations and processing expertise. At the same time, these companies are seeking to reduce the number of qualified vendors. Modern suppliers are being challenged to provide comprehensive technologies that support the entire product life cycle, from prototype to production.
Polyzen provides an excellent example for modern vendors of film-based medical constructions. The company offers expertise in polymers and custom formulations that minimizes development time by selecting the right material to meet performance and process requirements.For film extrusion, Polyzen offers comprehensive capabilities that include flat die extrusion, co-extrusion, coating and laminations, and multi-layer constructions. Extrusion equipment is designed to produce films in widths up to 52 inches (132 cm) and thicknesses ranging from 0.0005 to 0.070 inches (0.0127 to 1.778 mm), with in-line x-ray gauge reporting. All of these processes can be performed in a class 10,000 cleanroom environment.
Within the same facility Polyzen offers precision RF film welding utilising dielectric heat to seal very thin, hairline seams. This process can weld two or more layers of thin films together when making low pressure balloons, bags, and barrier sleeves for medical device assemblies. It is also a versatile process that can be used for welding low volume prototype quantities and high volume production levels.