Abstract: The invention relates to a process for the pretreatment of material surfaces in order to minimize the interaction between polycarbonate and metal and, in the processing and synthesis of polycarbonate, to obtain a high-quality polymer which in particular does not become discolored and is free of insoluble constituents.

Abstract: The invention relates to a process for the pretreatment of material surfaces in order to minimize the interaction between polycarbonate and metal and, in the processing and synthesis of polycarbonate, to obtain a high-quality polymer which in particular does not become discoloured and is free of insoluble constituents.

Abstract: A method for the decomposition of chromium ore in a directly heated revolving tube is described, in which oxygen-containing gases are introduced into the revolving tube by means of below-bed nozzles.

Abstract: A method for manufacturing alkali chromates by the reacting of chromium ore with alkali compounds and oxidation in an atmosphere containing at least 50% oxygen is described, in which the mixture consisting of chromium ore, alkali compound and optionally leaning materials is heated in a first stage in an atmosphere containing not more than 5 vol. % oxygen to a temperature between 1000.degree. and 1 400.degree. C., and in a second stage is oxidized at a lower temperature of 900.degree. to 1 070.degree. C. with supply of an atmosphere containing at least 50% oxygen.

Abstract: New, highly branched polyphosphonates which have a greatly improved flame retardant action compared with known polyphosphonates which are suitable as additives for plastics. In addition the new polyphosphonates may be incorporated in plastics as stabilizers with excellent migration properties.

Abstract: The present invention relates to a process for the preparation of alkali metal salts of 2-phosphonobutane-1,2,4-tricarboxylic acid, characterized in that 2-phosphonobutane-1,2,4-tricarboxylic acid penta-alkyl esters or partial esters are reacted with an aqueous alkali metal hydroxide solution in a ratio of from 0.5 to 0.76 mol, preferably from 0.6 to 0.7 mol of alkali metal hydroxide per mol of ester function at temperatures from 20.degree. to 200.degree. C. in a one-shot process.

Abstract: The new polyphosphonates, which are highly branched through polyfunctional phosphorus compounds, are suitable for use as moldings, fibers or films and as flameproofing agents and stabilizers in plastics. The new highly branched polyphosphonates show high resistance to thermal ageing and ensure good processability coupled with high migration resistance at elevated in-use temperatures.

Abstract: Aminomethanephosphonic acid aryl esters of the formula ##STR1## in which R.sup.1 is an aromatic radical and R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 independently of one another represent hydrogen atoms, ##STR2## groups, an optionally substituted C.sub.1-10 alkyl radical or an optionally substituted aromatic ring, or salts thereof.These aminomethanephosphonic acid aryl esters are useful as flameproofing agents in foams, thermoplastics and thermosets and as a crosslinking component in oligo-and polycondensates based on monomers containing hydroxy groups.