Improvement of catheter tip morphology by mold material used for tip-forming process

As interventional procedures using catheters have rapidly developed, accordingly, the incidence of polymeric embolization is also increasing, with the main cause being the flash generated during tip forming of the catheter. This study has performed to change the material of the mold used to form catheter tips to prevent flash, which is a cause of polymeric embolism. The tip-forming performance and the flash generation according to the main parameters of the tip-forming process were analyzed: power, heating, cooling time, and insertion pressure. In addition, we observed the effect of flash suppression according to temperature sensitivity by changing the mold material considering thermal conductivity and electrical resistivity. In particular, considering the glass transition temperature of HDPE (high-density polyethylene), which is applied to sheath and dilator catheters, the most stable tip forming proceeds when the temperature near the tip inside the mold was about 130°C. We verified experimentally and numerically that the temperature of the pins comprising the mold plays an important role in flash generation and confirmed that the viscosity of the polymer melts is lower at 120°C than at 90°C of the pin, and flash is minimized because of the shear-thinning behavior of the polymer melts.