Abstract: Method of production of a reflector wall having a core of thermosetting material enclosed in a skin of thermoplastic material, by two-material injection molding. Between a concave mold face having projecting points and a convex mold face, a thermoplastic skin material and a thermosetting core material having a polycondensation temperature greater than the plasto-elasticity temperature of the thermoplastic skin material are successively injected, while holding a temperature intermediate between the two temperatures; the points cause in the skin material interruptions permitting the emergence of the core material to the concave mold face, in localised zones of this in which open vents; the polycondensation of the core material and the hardening of the skin material is successively caused.

Abstract: The invention relates to a headlamp reflector for an automobile vehicle manufactured by injection molding according to the coinjection process using poly(alkylene terephthalate) having a viscosity number (DIN 16,779) of between 60 and 180 cm.sup.3 /g. It is characterized by the fact that the core contains some 15 to 75% by weight of hematite, at least 75% of the hematite having a particle size less than 70 .mu.m. Good mechanical strength and good behavior in respect of temperature.

Abstract: A method and apparatus for the production of parts made from plastics material using an injection press in which the mould cavity is defined by a mould surface Sca and the surface Sve of a movable piston. Firstly, the material is introduced into the mould cavity and during injection, the piston is kept stationary for a time to form a rough mould and then retracted to form a parison. Secondly, after injection has been completed the piston is advanced again, and maintained in position while cooling takes place. Thirdly, the mould is opened and the part ejected.

Abstract: The process for producing a shaped article comprising a polythene terephthalate (PETP) core containing from 0 to 50% of mineral fillers and a covering layer of a second thermoplastics material having a softening point below that of the PETP. The second material and the PETP are injected one after the other into a mould which is maintained at a temperature below the crystallization point of the PETP having regard to its fillers. The second material injected in the first phase acts as a thermal buffer slowing down temperature equalization between the PETP injected in the second injection phase and the mould, thus ensuring the required properties in the PETP core.