Plásticos y Materias Primas S.A. (PyMPSA), part of the PiSA Farmacéutica Mexicana group, manufactures medical devices and components for use in hospitals and healthcare facilities throughout Mexico and around the world. They have been leaders in the healthcare device industry for more than a quarter century.

Fig. 1 – Thermoplastic elastomer compounds were coextruded with a radiopaque component for epidural catheters.

One reason for their long-term success in a highly competitive industry is their ability to listen to, and act upon, feedback from their customers. When PyMPSA started hearing from doctors that some patients were complaining about the comfort of the catheter included in a multi-component epidural catheter kit, they took the comments seriously.

“Some doctors were saying, ‘it’s too hard’ or ‘it’s not comfortable for the patient.’ These were not good responses,” explained Oscar Gloria, R&D Manager at PyMPSA. “The catheter, which was designed to be easy to handle, might need to be inserted for several hours and it must be comfortable.”

Initially, another firm manufactured the nylon catheter in the kit for PyMPSA, a material PyMPSA had yet to process inhouse. Long an expert processor of PVC and similar plastics, PyMPSA took redesigning the catheter as an opportunity to expand their manufacturing capabilities and begin processing another resin. This move allowed them to reclaim “ownership” of the vital component, and, most importantly for long-term success, improve their brand’s quality and comfort.

Immediate Material Challenges

PyMPSA knew a polyamide-based thermoplastic elastomer (TPE) could be a challenging material to process. Exacerbating the challenge for their catheter application was the need to extrude two materials together—one for a radiopaque “stripe” that allows doctors to visualize the catheter in the body under fluoroscopy—combined with a second resin to form the tube shaped device.

Processing problems immediately developed, as apparent incompatibilities with the co-extruded materials caused turbulences in the extrusion process, producing air bubbles in the plastic, along with inconsistent properties. As is common, they turned to their material suppliers for assistance.

“In my experience, most resin suppliers just want to give you the materials they have on the shelf. They give you a list, and say ‘try this, then try this, then try this,’” said Gloria. “But we quickly got tired of guessing and testing things that didn’t work. It was a waste of our time and resources. We wanted to get materials that were made specifically for our application that had a good chance of working right away. But none of our existing suppliers could do that.”

Finding a Custom Compounder

Fortunately, at a subsequent trade show, they met representatives from thermoplastics compounder RTP Company, known for creating custom engineered plastics for individual applications requiring color, conductive, elastomeric, flame retardant, structural, wear resistance, or other specialized properties.

“RTP Company said that custom developing a pair of complementary thermoplastic elastomer compounds with a coextrudable radiopaque component for our application would not be a problem,” said Gloria. “We gave them our product specifications and let them get to work.”

Working with a local RTP Company sales engineer in Mexico and product development engineer Sean Cumiskey at RTP Company’s regional manufacturing facility in Ft. Worth, TX, quickly produced results for PyMPSA, noted Gloria, with RTP Company delivering material samples that, ultimately, solved their processing challenges. “It was just a few weeks, definitely less than a month,” Gloria recalled.

The key to success, according to Cumiskey, is being able to effectively communicate and understand technical issues from the customer’s perspective. Then, he said, we can then quickly apply our knowledge to create custom compounds to address those issues and meet the requirements of the application.

“What was initially discussed for this application were compounds based in identical resins, keeping one unfilled and adding a radiopaque modifier to the other,” explained Cumiskey. “But the addition of fillers often has effects beyond those intended, changing the compound’s modulus and melt-viscosity, along with radiopacity. Basically, the mismatch of material flexibilities and melt-viscosities would lead to processing problems when you try to extrude them together in a manufacturing process.”

Selecting a resin and additives from the company’s database of raw materials with a history of biocompatible compliance helped ensure successful ISO 10993 biocompatibility testing of the final product by PyMPSA. (See Figure 1)

Cumiskey sought to match the relative flexibilities and melt characteristics of the filled and unfilled materials to ensure that they processed easily together in the continuous co-extrusion process and successfully produced “tubing” for the epidural catheter. The result: two custom engineered RTP 2900 Series polyether block amide (PEBA) thermoplastic elastomer compounds were quickly sent to PyMPSA for evaluation.

Materials + Processing = Success

Getting the right material proved to be only one part of the challenge, efforts were also needed to optimize the coextrusion manufacturing process at PyMPSA’s facility. Exceeding the expectations of Gloria and his team, including PyMPSA design engineer Claudia Mancilla Ramirez and extrusion engineer Liliana Díaz, the supplier quickly stepped up to help on the processing end. An RTP Company processing expert worked onsite, side-by-side with the PyMPSA team to fine-tune process parameters and get things working perfectly.

Adding a Little Color

Now that they had a taste of their new partner’s capabilities, PyMPSA had another challenge for RTP Company: could they now provide the compounds in different colors so that PyMPSA could visually differentiate different diameter catheters for fast and easy identification in the procedure room?

Here again, the supplier’s custom compounding expertise was able to provide a solution. “There are a lot of variables to take into account to ensure success in the coloring process of a compound,” said Cumiskey. “It’s not just a matter of adding effective and accurate pigments, but also ensuring that the colorants don’t change other properties, such as those related to regulatory compliance, processability, or the quality of the finished product.”

RTP Company’s color formulations were on the mark, and PyMPSA was soon able to deliver different gauge catheters designated with white, blue and pink colors. Gloria noted that, while PyMPSA had offered colored products before, the RTP Company approach was new to them, and far preferable to how they were handling color previously.

“Before, we would buy a color masterbatch and pour it into the process,” Gloria said. “Now, RTP Company delivers the color, as well as the radiopaque additive, built right into the resin pellet, so we don’t have to mix things anymore. This saves us time and money, and helps us deliver a better product for the customer.”

Helping Build Market Share

PyMPSA’s innovative new catheter design is winning high marks from doctors and patients alike, for its outstanding performance as well as its improved comfort. In fact, according to Gloria, the company’s new epidural catheter kit, marketed under PiSA’s SET ESPICAT brand, has become far and away the market leader in Mexico for both private and government healthcare facilities.

“This is a result of many improvements we made to the kit, but there is no doubt that the catheter is the heart of it, and that RTP Company’s outstanding custom compounding and processing expertise helped bring our design to life,” said Gloria.

For Cumiskey, and his colleagues at RTP Company, they say that it’s all in a day’s work. “We hear all the time that most resin producers are not experts in compounding and they leave it alone because it can be so complicated. But custom compounding is what we do, and we enjoy helping customers meet their application challenges, and help them build their success in the marketplace,” he said. “It may not be typical, but we think it’s a great way to do business.”

The article was written by Josh Blackmore, Medical Marketing Manager, RTP Company, Winona, MN. For more information, Click Here  For more information on Plásticos y Materias Primas, part of the PiSA Farmacéutica Mexicana group, visit .