Elastomer Aids Technology, Eliminates Solvent, Adhesive

Creating successful medical applications that deliver effective, safe and accurate patient solutions often requires forging partnerships with the right mix of technological knowhow. Natvar, a Tekni-Plex company and a manufacturer of extruded products for the medical market, and Gentex Corporation, manufacturer of colorless laser welding technologies, recently partnered to develop the Sure Bond tubing solution. This tubing with Gentex's Clearweld additive technology enables medical tubing to be laser welded to transparent medical components used in intravenous therapy, hemodialysis, cardiovascular, urinary drainage, catheterization, neonatal, and angioplasty applications.

The Clearweld additive eliminates the need for solvent or adhesive bonding, which often leaves behind residual bonding material. In addition, laser welded medical tubing helps eradicate the quality challenges that can occur when connecting a tube to a lure (connector), including leaking, occlusions, and crazing that might compromise a medical product's proper function. The ability to laser weld also creates a number of processing efficiencies, including a faster cycle time and reduced consumables. For example, with less bond surface area needed to weld, component manufacturers have the potential to reduce up to 50% in the amount of lure material needed in their applications.

Key to the success of the project was the role of Eastman Chemical Co., who applied its medical plastics expertise and assisted both companies in the selection of its Ecdel elastomer as the outer layer of Natvar's 252 tri-layer tubing used for the delivery of unstable medications. The elastomer is the material critical in ensuring that the Sure Bond layer is clear, has optimal joint strength, and has excellent product integrity.

"Gentex's Clearweld additive technology allows our medical tubing to be laser welded to other medical parts without compromising product performance," says Bob Donohue, divisional director of technologies for Natvar. "Gentex's proprietary technology and Eastman's Ecdel (a copolyester elastomer, COPE) medical plastics solution guarantees our customers are getting the best-performing medical tubing on the market." The Clearweld additive technology is based on speciallydesigned organic absorbers. It enables a clear-to-clear weld that provides the necessary clarity and visibility medical personnel need when monitoring fluids being administered to patients via specialized tubing.

The Sure Bond manufacturing process incorporates near infrared-absorbing colorless additives that are compounded into a thermoplastic before they are extruded into medical tubing. These light-absorbing additives focus laser energy at a wavelength of 808nm to 1,090nm, converting it to heat. Localized heating at the interface of the lure and tube produce strong (60 lb to 70 lb), hermetically sealed welds with minimal thermal and mechanical stress or presence of particulates. The Clearweld technology produces a far superior bond than solvent or adhesive bonding, and creates assembly line efficiencies.

Market advantage

Clearweld technology has brought the tube-joining process of clear-to-clear parts to the next level. The Clearweld additive technology is non-invasive to the fluid path and can be used effectively within the high pressure injector tubing market. Sure Bond tubing withstands pressures better and helps avoid catastrophic bond failure during intense surgical procedures. As a result, Sure Bond medical tubing is a more robust, effective product that can be used for a variety of patient-care products.

"Our goal was to create tubing products that provided our customers with a solution to their bonding issues, effectively meeting the needs of a wide range of medical markets," states Donohue.