Method for manufacturing disk-shaped information carriers

In a method for manufacturing disk-shaped information carriers with a high storage density which can be optically read out, of the type manufactured out of transparent synthetics employing a molding press equipped with at least one pressing matrix, the press havng a compression form comprised of separable mold halves which can be moved towards one another and both of which have means for heating and cooling during the pressing cycle, wherein the improvement comprises:

• said mold halves each being provided with an annular ridge, the ridges lying opposite one another so as to form a squeezing gap when the mold is closed and serving as an outer boundary for the hollow space of the mold at which material can flow through the gap;
• preheating the transparent synthetic material to a temperature significantly greater than the initial pressing temperature of the compression form;
• injecting an excess of the preheated material than is required for the finished product into the compression form via a central aperture in one of the mold halves so as to form a lump of material;
• pressing the lump of material by closing the compression form to obtain a squeezing gap width with a magnitude equal to several tenths of the thickness of the finished storage disk, said squeezing gap maintaining a pressure in the pressed material while permitting excess material to squeeze therethrough, said pressing step being initiated prior to the termination of the injecting step;
• cooling the compression form, said cooling step being initiated prior to the termination of the pressing step;
• and
• the pressing and cooling steps chronologically proceeding in an internal sequence which approximates an exponential function so that along with the use of the squeezing gap condensation bubbles and double diffraction effects due to frictional and shearing forces are substantially avoided.