PROCESS FOR PRODUCTION OF HEAT-RESISTANT HOLLOW ARTICLES MADE OF POLYLACTIC ACID-CONTAINING RESIN

摘要

The invention provides a process for the production of heat-resistant hollow articles which is free from deformation of injection moldings or failures in withdrawing them from the mold. The injection of a polylactic acid-containing resin is conducted by using a mold (1) which comprises a female die (3) having a concave (2), a male die (5) having a convex (4), and a stripper plate (7) having an edge-forming part (6) and in which a cavity (8) enclosed by the concave (2), the convex (4) and the edge-forming part (6) is formed, heating the mold (1) in such a way that the temperatures of the surfaces fronting the cavity (8) become the crystallization temperature of the resin, and injecting the resin into the cavity (8) through a gate (9). The temperature of the resin injected into the cavity (8) is determined with an infrared temperature sensor (12), and the male die (5) and the stripper plate (7) are moved in such directions that they leave the female die (3), when the temperature of the resin lies between the temperature (T<SUB>1</SUB>) at which the heat resistance is developed and the temperature (T<SUB>2</SUB>) at which the withdrawal becomes impossible. Air is introduced between the inside surface of a hollow article (A) and the convex (4) of the male die (5) to conduct mold release. Then, the stripper plate (7) is moved toward the hollow article (A) to thereby withdraw the article (A) from the mold (1).