Resorbable plastic implants production - by extruding rectangular poly-L-lactide cross=section and stretching it within specific temp. range to acquire high mechanical strength

摘要

Resorbable plastic implants are produced by drawing off the material at above its melting pt. from an extruder and increasing the strength of the material at elevated temps. by stretching the extrusion; it is stretched immediately after being drawn off and before it has cooled to below its stretching temp.. The stretching stage pref. uses poly-l-lactide as the resorbable polymer. The method is partic. intended for implants for osteosynthesis. The components of the polymer concerned are mixed together in the reaction extruder to form the polymer which is expressed as a rod from a die e.g. with a rectangular cross-section. The extrusion is drawn off by the rollers at the rate of extrusion. Further rollers apply tension as they run at a higher speed. The extrusion is thus stretched. All the rollers are below the m.pt. of the extrusion but above its crystallisation pt.; using poly-l-lactide this is stretching at between 105 and 160 deg.C. A perforating device with roller cools the product which can also be shaped as required. The material is then cut to length. ADVANTAGE - The procedure provides products with high mechanical strength.