In Anbetracht begrenzter Deponiekapazitaeten in Deutschland und der Probleme, die die Gummireststoffe bei der Verbrennung bereiten und nicht zuletzt im Sinne der Kreislaufwirtschaft, kann nur das werkstoffliche Recycling auf hohem Niveau das Ziel sein. Dabei wird die Rueckfuehrung in die Primaerproduktion angestrebt. Wiederverwertungsmoeglichkeiten fuer die TSE-Werkstoffe muessen aufgezeigt sowie technisch und wirtschaftlich beschrieben werden. Die hierfuer zu entwickelnde, auf den TSE-Bereich ausgerichtete Technik kann spaeter auch auf das Recycling von Altreifen uebertragen werden. Zentralpunkt der werkstofflichen Aufbereitung ist die Feinstzerkleinerung. Mittels vier ineinandergreifender Teilstufen soll die Wirtschaftlichkeit der Gesamtkonzeption 'Feinstvermahlung' technisch und wirtschaftlich realisiert werden. In den Stufen 1 und 2 werden die Einfluesse von Gummirecyclat auf verschiedene Verarbeitungsmoeglichkeiten untersucht. Dazu gehoert der bei BTR Metzeler eingesetzte Extrusionsprozess auf Metallcarriern mit anschliessender UHF-Vulkanisation.
Objective: The purpose of the research is: - to establish by measurement whether and to what extent substances contained in the rubber are dispersed into the atmosphere, especially during abrasion of damaged areas of conveyor belts or joint ends, with the result that workers are exposed to hazardous substances in particulate form; - to determine the hazardous vapour or gas emissions occurring when adhesives and rubber solutions are applied, often over large areas, to belt sections which require repair or joining and to the new pieces of belt cover to be fitted and to attempt to derive relationships between the components of the materials used and exposure to hazardous substances at the workplaces; - to measure and assess the hazardous vapours and gases produced in the course of hot and/or cold vulcanisation or of the curing of adhesive splices, with particular reference to the release of nitrosamins. General Information: Vulcanisation is the three-dimensional cross-linking of rubber in the presence of sulphur and heat to form a network structure, converting the rubber from a plastic to an elastic state. Since vulcanisation by the action of sulphur and heat is slow, various substances are added to the raw material to accelerate and control the process. In hot vulcanisation the main additives are: - accelerators such as xanthates, dithiocarbamates, thiurams, thiazoles, guanidines, thiourea derivatives, amine derivatives; - activators such as zinc oxide, antimony sulphide, litharge; - fatty acids such as stearic acid; - retarders such as organic acids (benzoic/salicyclic acids, phthalic anhydride, N-nitrosodiphenylamine); - fillers such as carbon blacks, silica gel, kaolin, chalk, talc; - pigments such as organic dyes, lithopones, metallic oxides (Fe, Cr, Cd); - softeners such as mineral oils, ethers and esters; - mastication additives such as chlorinated thiophenols and their zinc salts; - antidegradants such as aromatic amines, phenols, phosphites, waxes; - fire retardants such as chlorinated paraffins, halogenated alkyl phosphates. Furthermore, blowing, preserving, antistatic, mould release and bonding agents are added to obtain particular properties. Although cold vulcanisation is nowadays scarcely used for production, it still has a certain importance in repair work, in which no clear distinction is made between vulcanisation and splicing using adhesives. A common feature of both the cold vulcanisation and adhesive splicing processes, however, is the use of solvents which may have a carcinogenic potential, in particular chlorinated hydrocarbons. In the repair of conveyor belts underground, which primarily consists in making joints to form endless belts and in repairing damaged areas, the first stage is to remove the face and back covers by cutting and/or abrasion and to clean the strength members - the textile or steel carcass. Bonding or adhesive agents, rubber solutions etc are then applied and the belt is reconstructed with new or ...