Surgical Tubings Using Natural Rubber Latex by Extrusion Process

Manufacturer: We intend to manufacture medical/surgical tubings from natural rubber latex. These are for transfusion, anaesthetic apparatus, tourniquets, etc. Please explain what the process would entail.


John Woon (Senior Latex and Rubber Consultant): I suggest you try extrusion with heat sensitised latex compound. A prevulcanised latex is preferred to post-vulcanisable latex compound. The ammonia must first be reduced to  pH to 7.0 - 7.5. You might have to use formaldehyde solution for this. This is followed by  the addition of a heat sensitising agent one good example of which is Polyvinyl methy ether.

Once your latex is heat sensitised, it must be stored at temperature below 20°C to prolong its shelf life.

The latex from a tank at a constant head is then pass through a glass extrusion tube (in which there is a glass rod) through gravity. The extrusion tube is being heated in a jacket with hot water and maintained at a  50°C to 60°C.

The extrudate ( i.e. tubing) emerges from the outlet of the glass extrusion tube in a firmly gelled state and is allowed to go into a tray where it is leached, dried and vulcanised (if necessary). Details of latex formulation, compounding, pH adjustment and the extrusion equipment set-up have been sent to you separately.

For short tubings you could use the simpler coagulant dipping process.