Abstract: A process for cooling a heated polymer film by applying to both surfaces of the heated film, a cooling liquid adapted for wetting contact with the film surfaces. The viscosity of the layers of liquid adhering to the film surfaces is significantly reduced to facilitate removal of such liquid layers. The viscosity can be reduced by significantly raising the temperature of the adhering liquid layers after the film has been sufficiently cooled or by changing the adhering liquid to a different liquid of lower viscosity. Preferably, the liquid layers are removed for the film surfaces by conveying the liquid carrying film upwardly to cause the liquid layers to each form into a generally triangular shape with the vertex extending upwardly and blowing air stream downwardly against each such vertex.

Abstract: A process of cooling a heated polyethylene terephthalate film by applying cooling liquid to both surfaces of the heated film and, after the temperature of the film has decreased sufficiently, removing the cooling liquid from the film, wherein the cooling liquid has a pH value between 6 and 3.

Abstract: A method and device for longitudinally stretching polymeric film, characterized by the strict isolation of the tensioning operation from the heating and the cooling operations of the film, by the symmetrical heating and cooling of the film, and by carrying out the heating of the film in two stages, namely preheating by means of diffused IR-radiation, and a full heating, preferably along a line, by means of bundled IR-radiation. The film stretched in this manner meets high standards of flatness and surface quality, and is subject to minimum waste losses and is especially useful in the photographic field.