Minnesota Rubber and Plastics

Challenge

Develop a trocar seal material meeting four critical properties.

Trocars are surgical instruments placed in the body during laparoscopy. The trocar’s seals prevent air from escaping the abdominal cavity while creating an access point for surgical instruments to pass through. The seals also maintains air pressure to provide the surgeon with a clean viewing area during surgery.

An existing Minnesota Rubber & Plastics customer was developing a new trocar seal. Their selected material was failing to work as needed. Of primary concern, some of the more aggressive surgical instruments would catch on the material during insertion, often tearing the seal. This reduced the physician’s control over the instruments, disrupted their view of the surgical area and increased potential risk to the patient.

The customer turned to Minnesota Rubber & Plastics to provide a better material for their new seal. The material needed to be tough and tear resistant to withstand a variety of instruments, including scissors, dissectors and graspers. The material also needed to maintain a minimum compression set to ensure consistent performance over the lifetime of the product. Critically the material needed a low coefficient of friction (CoF) to support accurate manipulation of instruments and prevent the snags and tearing that occurred with the original material.

Solution

A custom formulation and process for easier production.

Minnesota Rubber & Plastic’s Advanced Material Group (AMG) began work on a formulation that would meet the multiple properties required. The AMG formulation library, and the AMG team’s experience with high-performance trocar applications, accelerated the identification of an existing material that closely met the needs of the customer.

The material selected was a polyisoprene (synthetic natural rubber). Polyisoprene has very high elongation (+700%) and tear strength. It snaps back quickly and has good compression-set resistance. It is difficult to cut and, once cut, the cut does not easily propagate.

Using the existing polyisoprene as a base, the team customized the formula to match all of the customer’s performance requirements, except for the low CoF.

During development of the custom material, the AMG team determined an advanced secondary process utilizing our proprietary Quniton® surface modification technology could be used to lower the CoF on the seal while improving the manufacturing process. Plus, this secondary process helped to maximize the other properties required from the material while keeping costs down.

In addition to the secondary process, the AMG team drew from their extensive manufacturing experience to improve the customer’s seal geometry. The design took advantage of the new material’s properties and helped ensure a consistently reliable product could be manufactured at scale.