Abstract: A novel perylene-3,4,9,10-tetracarboxylic acid diimide of the formula ##STR1## is very useful as a black dye or, together with white pigments, as a gray dye.

Abstract: A process for the drying of inorganic hydrogels obtained from readily hydrolyzable compounds of the elements Al, Si, Ti, B, La, Zr, Cr, Sn, Th or Mg, and organic hydrogels based on gelatine, albumin or agar agar, from CO.sub.2, to give aerogels is easy to carry out industrially, and drying can be effected at from room temperature to 90.degree. C.The resulting aerogels are transparent and have a low bulk density and low thermal conductivity.The aerogels can be used as packing materials for liquid chromatography, as catalyst carriers, as substrates for enzymes and as adsorbents.

Abstract: An electrophotographic recording medium which consists essentially of an electrically conductive base and a photosemiconductive double layer which comprises a first layer containing charge carrier-producing dyes, and a second layer containing one or more compounds which are charge carrier-transporting when exposed to light, wherein the charge carrier-producing dyes are dark in color, possess substantially panchromatic absorption characteristics, and are of the general formula ##STR1## where R.sup.1 is propyl, 1-hydroxypropyl, 1-methoxypropyl or 1-phenylethyl, Z is p-phenylazoanilino, phenylthio or anilino, and n is 0-6, and a process for the production of this electrophotographic recording medium.

Abstract: A process for the preparation of deeply colored organic pigments by crystallizing finely divided crude organic pigments, whose primary particles have a size of .ltoreq.0.2 .mu.m, in C.sub.3 -C.sub.5 -alkanes, C.sub.3 -C.sub.5 -alkenes or C.sub.1 -C.sub.3 -chloroalkanes at from 40.degree. to 250.degree. C. to under atmospheric pressure or superatmospheric pressure, and isolating the pigment.The pigments obtained by the process give deep, brilliant colorations.

Abstract: A perylene-3,4,9,10-tetracarboxylic acid diimide of the formula ##STR1## gives black colorations with excellent lightfastness and weathering fastness, in polyethylene, PVC, surface coatings, inks and aqueous dye formulations.

Abstract: Novel perylene-3,4,9,10-tetracarboxylic acid diimides of the formula ##STR1## where R.sup.1 and R.sup.2 are each isopropyl or R.sup.1 is methyl or ethyl and R.sup.2 is C.sub.3 - or C.sub.4 -alkyl, give clear, luminous, very lightfast, fluorescent orange colorations in plastics.The dyes are particularly suitable for concentrating light.

Abstract: An electrophotographic recording medium which consists essentially of an electrically conductive base and a photosemiconductive double layer which comprises a first layer containing charge carrier-producing dyes, and a second layer containing one or more compounds which are charge carrier-transporting when exposed to light, wherein the charge carrier-producing dyes are those of the formula I ##STR1## or of the formula II ##STR2## where R.sup.1 is hydrogen, alkyl, aralkyl, alkyl or alkylaryl, and Z may be a a fused aromatic system, and the degree to which the aromatic skeleton is halogen-substituted is from 45 to 75% of the maximum possible, and a process for the production of this electrophotographic recording medium.

Abstract: An electrophotographic recording medium which consists essentially of an electrically conductive base and a photosemiconductive double layer which comprises a first layer containing charge carrier-producing dyes, and a second layer containing one or more compounds which are charge carrier-transporting when exposed to light, wherein perylene-3,4,9,10-tetracarboxylic acid N,N'-bis-(2',6'-dichlorophenyl)-diimide is employed as the charge carrier-producing dye, and the production of this recording medium.

Abstract: A process for concentrating light by means of fluorescent compounds of the formula ##STR1## where the R.sup.1 's independently of one another are ortho-substituted aromatic or heterocyclic radicals which do not contain groups which confer solubility in water, and novel perylene-3,4,9,10-tetracarboxylic acid diimides of the formula I, where R.sup.1 is ##STR2## A.sup.1 and A.sup.2 being hydrogen, or one of A.sup.1 or A.sup.2 being isopropyl and the other being hydrogen.The compounds I are very lightfast and convert incident light into fluorescent light with high efficiency.

Abstract: A process for drying finely divided pigments contained in a press cake or a suspension, wherein a mixture of the pigment and a liquid whose critical temperature is below the decomposition temperature of the pigment is heated under pressure to above the critical temperature of the liquid and is then released while keeping the temperature above the dew line of the liquid. The process gives fine pigments powders which are easily dispersible in the media in which pigments are used, and which produce deep, brilliant colorations.

Abstract: A process for converting a crude, coarsely crystalline perylene-3,4,9,10-tetracarboxylic acid diimide of the formula ##STR1## where A is unsubstituted or substituted phenyl, an unsaturated 5-membered or 6-membered heterocyclic ring which contains one or two nitrogen atoms and may be fused to a benzene nucleus, C.sub.3 -C.sub.6 -alkyl, or C.sub.2 -C.sub.3 -alkyl which is substituted by C.sub.1 -C.sub.4 -alkoxy, phenyl or C-acylamino, to a pigmentary form, wherein the crude pigment, in aqueous suspension, is comminuted in a high-speed mill in the absence of a surfactant.The pigments obtained give pure shade colorations of high to extremely high hiding power, and have a high tinctorial strength in white reductions.

Abstract: A process for the preparation of a high-hiding, deeply colored pigmentary form of perylene-3,4,9,10-tetracarboxylic acid bis-(4'-ethoxyphenyl)-imide by heating the finely divided crude pigment, which is in the form of agglomerates, formed from primary particles of length 0.15 .mu.m or less, in cyclohexanone or a mixture of cyclohexanone and water at from 30.degree. to 200.degree. C., and isolating the pigment.

Abstract: Electrically conductive organic perylene derivatives and their use. They have the formulae ##STR1## where R is hydrogen, alkyl or oxaalkyl of 1 to 10 carbon atoms, cycloalkyl, alkaryl or aryl which is unsubstituted or substituted by from 1 to 3 alkoxy, halogen, nitro or amino, or is hydroxyalkyl-CH.sub.2 -(CH.sub.2).sub.n -OH, where n is an integer from 1 to 10, and which may or may not contain oxa groups, and R.sub.1 is one of the following divalent radicals which join the two N atoms to form a ring: ##STR2## The compounds may be used for the manufacture of electrically conductive systems and of semiconductors.

Abstract: Pyranthrone pigments of the formula ##STR1## WHEREIN N IS 0 OR 1, WHEREIN WHEN N IS 0, EACH A is hydrogen or chlorine, and when n is 1, each A is chlorine are prepared by crystallizing a finely divided crude pyranthrone pigment in an organic polar solvent, in the presence of from 0.5 to 10% by weight, based on the crude pigment, of an anthraquinone compound of the formula ##STR2## WHEREIN X is chlorine, Y is alkyl of 1 to 4 carbon atoms, hydroxyl, carboxyl, carbo-alkoxy, wherein said alkoxy group has 1 to 4 carbon atoms, or carbophenoxy, p is 0, 1 or 2 and m is 0, 1 or 2.

Abstract: Dye formulations for transfer printing which in addition to conventional ingredients contain dyes of the formula ##STR1## in which R.sup.1, R.sup.2 and R.sup.3 are hydrogen, hydroxy, chloro, bromo or alkylamino substituents, one of R.sup.1 to R.sup.3 being different from hydrogen. The dyes are distinguished by a comparatively very low transfer temperature.

Abstract: A process for the mass coloration of polyamide chips in which a dye of the formula ##SPC1##In which R is hydrogen or chloro is used. The dye is absorbed quantitatively or virtually quantitatively from the aqueous phase. After shaping, pure blue colorations are obtained having great thermal stability.