Abstract: In a process for the production of hollow bodies from thermoplastic material by blow molding, an additional body is disposed inside the hollow body by being carried on a holding means which is joined to the inside surface of the wall of the hollow body. The additional body is disposed on the holding means at a spacing from the inside surface of the wall of the hollow body while that surface is subjected to a treatment with a treatment medium, so that the treatment medium has adequate access to the wall of the hollow body in the region of the additional body. After termination of the treatment the additional body is then moved on the holding means into a final position in which it is disposed at least closely adjacent to or in contact with the inside surface of the wall of the hollow body.

Abstract: A process for the production of a laminate of thermoplastic material with a multi-layer wall by co-extrusion provides that added to the material for forming at least one of the layers of the laminate is a substance which makes it possible for that layer to be rendered recognizable in the laminate by the action of physical and/or chemical means. The added substance may be a fluorescing, phosphorescing or luminescing substance so that the layer containing that substance can be rendered visible in the wall of the laminate by the action of UV radiation of appropriate wavelength.

Abstract: In producing hollow bodies by blow molding from thermoplastic material, a preferably tubular preform is firstly formed, and is then expanded within the blowing mold under the effect of an inert gas under high pressure, until it bears entirely against the inside surface of the blowing mold. Thereafter, a reaction gas such as fluorine is introduced into the hollow body under a considerably lower pressure, while the hollow body is still in the mold, to treat the internal surface of the hollow body to render it impervious to gas and/or liquid. After the reaction has elapsed, a flushing and cooling gas is introduced into the hollow body and is then removed from the blowing mold after the hollow body has sufficiently set.

Abstract: In producing hollow bodies by blow molding from thermoplastic material, a preferably tubular preform is firstly formed, and is then expanded within the blowing mold under the effect of an inert gas under high pressure, until it bears entirely against the inside surface of the blowing mold. Thereafter, a reaction gas such as fluorine is introduced into the hollow body under a considerably lower pressure, while the hollow body is still in the mold, to treat the internal surface of the hollow body to render it impervious to gas and/or liquid. After the reaction has elapsed, a flushing and cooling gas is introduced into the hollow body and is then removed from the blowing mold after the hollow body has sufficiently set.

Abstract: The conventional process of manufacturing hollow bodies with multi-layer walls using extrusion and blow molding techniques is improved by first making a preform of a thermoplastic carrier layer with an adhesive layer on one or both sides and then applying the additional layer or layers to the adhesive layer(s) in a separate operation. The additional layer(s) has properties different from the carrier layer and serves as an insulation or barrier layer to shield the carrier layer from substances to be contained by or which will surround the hollow body. Among other advantages, the improved process allows recycling of waste and surplus preform material, stronger heat-seal seams in the hollow bodies, less complicated extrusion equipment and more economic use of expensive barrier layer materials.