Eastman’s Tritan targets renal market

Eastman Chemical Co.'s (Kingsport, TN) Tritan copolyester suite has added a fourth grade for the medical market, with the latest version targeting renal-care products. In addition to chemical resistance to blood and lipids, the new grade avoids environmental stress cracking when exposed to chemical agents, including isopropyl alcohol, disinfectants, and bonding solvents.

Eastman's Kieran Smith told PlasticsToday that as medical facilities combat hospital acquired infections (HAI), especially now that many insurers, and even Medicare and Medicaid, have refused to cover charges relating to HAIs, they are turning to ever more aggressive cleaners.

To prove the wherewithal of its latest Tritan, MX811, Eastman used a visual display. Four injection molded test plaques had a screw drilled through them using a torque wrench to ensure they were under the same amount of pressure. The test plaques, which where made from a lipid-resistant polycarbonate (PC), acrylic, general-purpose PC, and Tritan, where soaked in Virex TB cleaner and, save for the Tritan sample, all showed varying degrees of crazing and cracking after only a few hours. In addition to chemical resistance under applied stress, Eastman looked at resistance in residual stress, with more good performance from Tritan.

Besides its BPA-free appeal over PC, Tritan offers good flow characteristics, is suitable for solvent bonding, and does not requiring annealing. Eastman also said the new Tritan MX811 copolyester draws interest for its ability to withstand higher processing temperatures, which is key when it replaces PC.

In terms of melt flow rate (MFR), MX811's MFRs ranged from 10 to 12, compared to an MFR of 6-7 for lipid-resistant PC, 16 for standard PC, and 20-22 for high-flow PC.

The first acute renal care market manufacturer to utilize the new Tritan is Minntech Corp., which applies the material in  its Hemocor HPH Hemoconcentrators and Renaflo II Hemofilters, with the first device used as a fluid-removal device in cardio bypass surgery, and the latter applied in intensive care units for treatment of acute renal failure, including fluid removal and kidney stabilization. Both devices will be available following regulatory submission and approval

In the two years since Tritan was introduced into the medical market, Dante Rutstrom, VP and general manager Eastman's specialty plastics business, said the material has made steady inroads into the sector. "In the medical market, products take a long time to develop, and it can take a long time to gain acceptance of the materials," Rutstrom said. "We've been pleased with Tritan's progress so far." The initial push for Tritan was in North America and Europe, but Eastman, is now pushing the material into Asia and Latin America.

Tritan is suitable for gamma, e-beam radiation, and ethylene oxide (EtO) sterilization, promising superior optical clarity after sterilization compared with PC and polyolefins.