Abstract:
Methods of making oxidation and wear resistant polymeric materials using peroxide cross-linking and high temperature melting process are disclosed. A multiple step procedure for enabling the manufacturing of such material without size limitations is also disclosed.
Abstract:
A method of molding a component includes the steps of providing a plurality of fibers, applying the fibers with a low temperature sizing to form a plurality of sized fibers, forming a preform from the plurality of sized fibers, placing the preform in a mold, and de-sizing the preform by heating the mold to an initial temperature that is sufficient to break down the low temperature sizing to a gaseous phase. A molding apparatus is also disclosed.
Abstract:
The processes and resins of the present invention allow the extrusion of polymer products, such as polymer films, that have a reduced occurrence of surface aberrations, e.g., surface melt fracture and/or haze bands and/or haze. Preferably, the polymer products produced in accordance with the present invention are substantially free of surface aberrations even when manufactured under conditions of high sheer stress such as those conditions that occur at commercial production rates. In part, the present invention provides processes for polymer extrusion wherein the resins employed are treated using heat in an atmosphere sufficient to substantially eliminate the tendency to create surface aberrations. The resins can have reduced or substantially eliminated concentrations of low molecular weight components. In some embodiments, both the polymer resins and the extruded polymer products have reduced concentrations of processing aid(s), e.g., the polymer resins and the extruded polymer products are substantially free of processing aid(s).
Abstract:
Process pre-treating a mass of thermoplastic resin in its pelletized state, such as P.E.T., which precedes or anyway integrates the drying treatment and consists in maintaining said resin in a flow of inert gas heated to approx. 170 DEG C for a period of not less than two to three hours, so as to allow said mass of resin to be thoroughly exposed to said flow of inert gas. The purpose of this process is to remove as much free oxygen as possible from said mass of resin, so that the final moulded products obtained from the same resin, i.e. food-grade containers, are almost free from oxygen that might migrate to the food held in the same containers and contaminate it. In a preferred manner, said inert gases are nitrogen or carbon dioxide. The apparatus that carries out this process comprises a container provided with inert-gas blowing means, inert-gas suction means, inert-gas pre-heating means, as well as means for transferring the material from said container to a feeding hopper, under fully sealed conditions with respect to the outside ambient.
Abstract:
Methods of making oxidation and wear resistant polymeric materials using peroxide cross-linking and high temperature melting process are disclosed. A multiple step procedure for enabling the manufacturing of such material without size limitations is also disclosed.
Abstract:
Eine Vorrichtung zum Entfernen von Verunreinigungen aus einer Kunststoffschmelze weist eine unter Unterdruck stehende Kammer (25) mit wenigstens einer Öffnung (26) auf, durch welche die Kunststoffschmelze in die Kammer (25) eintritt. Die Kunststoffschmelze fällt in Form von dünnen Schmelzefäden durch die Kammer (25) nach unten und Verunreinigungen wie Wasser diffundieren an die Oberfläche und verdampfen durch die Temperatur und den Unterdruck.
Abstract:
A process for preparing food contact grade PET from a waste stream containing PET and non PET materials is disclosed. The process involves the steps of sorting at least some of the non PET materials from the waste stream, followed by dividing the PET containers into flakes of preferable maximum size approximately 10mm, followed by washing the flakes in a hot aqueous medium containing alkaline materials and surfactants, preferably non-ionic, to remove particulate and absorbed contaminants from the surfaces of the flakes. This step is followed by de-watering and then drying the flakes to a moisture content of 0.1 % w/w maximum, and more preferably 0.01 % w/w maximum. The next step involves removing absorbed contaminants and moisture by heating and vigorously mixing the flakes under vacuum, preferably 1-10 millibar, more preferably 2-7 millibar and at a temperature less than the melting point of PET, preferably in the range 170-220 DEG C for at least 30 minutes, preferably at least 60 minutes. The final step involves melting the flakes in a screw extruder equipped for vacuum processing and extruding the molten material to form strands that are pelletised.
Abstract:
For the purpose of conducting injection molding of an aromatic polyester preform through advantageous exposure of a melt of the aromatic polyester to a reduced-pressure atmosphere, the production of an aromatic polyester preform is conducted by the use of a molding machine provided with vent holes at specified positions in order to evacuate the machine, whereby a preform lowered in acetaldehyde content can be advantageously produced.