Chemische Werke Huls Aktiengesellschaft

Herbert Haferkorn

Fritz Gude

Heinz Riemer

Felix Schulde

Gunter Dormann

The invention relates to a process for removing naphthoquinone from phthalic anhydride produced by the air oxidation of naphthalene or mixtures containing naphthalene. Specifically, crude phthalic anhydride containing naphthoquinone is treated at a temperature of 180.degree.-280.degree. C. with an unsaturated aliphatic oil produced by the polymerization of 1,3-dienes and optionally isomerized having a molecular weight of 800-5,000, and optionally in the presence of 1-40 ppm of alkali ions, relative to the crude phthalic anhydride.

Process for removing naphthoquinone from phthalic anhydride produced

The object of the invention is a process for the production of flat varnishes based on powder coatings of 1,2-epoxy compounds with at least one 1,2-epoxy group in the molecule and a lower melting point of &gt;40.degree. C., salts of aromatic carboxylic acids with 3 and more carboxyl groups and imidazolines as curing agents, as well as the usual additives and the application of the powdered varnish upon the objects to be varnished and heating of these objects to temperatures of 160.degree.-240.degree. C., whereby the salt of 2-phenyl-methyl-.DELTA.2-imidazoline and trimellitic acid is substituted up to 60 mole % by a salt of 2-phenyl-.DELTA.2-imidazoline and trimellitic acid.

Process for the production of flat varnishes

Terpolymers of maleic anhydride, dicyclopentadiene, and a vinylcyclohexene, preferably 1-vinylcyclohexene-3, are highly effective paper sizing materials.

Copolymer of maleic anhydride, dicyclopentadiene and vinylcyclohexene

A process for the fractional desublimation of pyromellitic acid dianhydride in the form of free-flowing crystals which comprises reducing a reaction gas containing pyromellitic acid dianhydride produced by a chemical reaction which also produces by-products, to a temperature above the thaw point of the by-products but below the desublimation point of pyromellitic acid dianhydride by means of a smooth thermostaticized cooling surface, directing the reaction gases at maximal flow velocities of 3 m/sec parallelly to the cooling surface and separating the fraction of crystals not adhering to the surface.

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Bottrop, Germany

Herbert Haferkorn