Abstract: The present invention refers to a lighting device (10) and a method of operating this lighting device (10). A lighting module (13) having a light element series connection (15) of several semiconductor light elements (14) is connected to the output (12) of a drive circuit (11). The control means (20) is provided which is configured to adapt a heating condition if a heating requirement is fulfilled. In the heating condition a heating means (26) is activated by the control means (20) to heat the lighting module. The heating requirement is fulfilled when the temperature (T) of the lighting module (13) drops down to a minimum temperature value (Tmin). In so doing an undesired increase of the forward voltage (Vf) of the light element series connection (15) can be avoided.

Abstract: The present invention refers to a lighting device (10) and a method of operating this lighting device (10). A lighting module (13) having a light element series connection (15) of several semiconductor light elements (14) is connected to the output (12) of a drive circuit (11). The control means (20) is provided which is configured to adapt a heating condition if a heating requirement is fulfilled. In the heating condition a heating means (26) is activated by the control means (20) to heat the lighting module. The heating requirement is fulfilled when the temperature (T) of the lighting module (13) drops down to a minimum temperature value (Tmin). In so doing an undesired increase of the forward voltage (Vf) of the light element series connection (15) can be avoided.

Abstract: By-products from the chlorination of butadiene may be reacted with phenols in the presence of iron catalysts to form Novolak type phenol resins.

Abstract: Phenolic resins obtainable by Friedel-Crafts alkylation of phenols with polyfunctional compounds are eminently suitable as a reinforcing resin for rubber vulcanizates.

Abstract: Secondary products formed in the chlorination of butadiene can be reacted with phenols in the absence of iron catalysts to form novolak-like phenolic resins in such a way that the tetrachlorobutane present in the secondary products does not react. It can be distilled off with the excess phenol and isolated in pure form from the distillate obtained.

Abstract: Phenolic resins obtained by condensation from alkylphenol, aldehyde, polyamine and polyether in a molar ratio of 1:0.7 to 1.3:0.005 to 0.2:0.001 to 0.3 are suitable as tackifiers for rubber mixtures.

Abstract: A mixture of azodicarbonamide and an .alpha.-amidosulphone corresponding to the general formula: ##STR1## in which R represents hydrogen, a C.sub.1 -C.sub.4 -alkyl residue and/or halogen,x represents numbers from 0 to 5,y represents numbers from 1 to 3, corresponding to the valency of R.sub.1,R.sup.1 represents an aromatic carboxylic acid residue or sulphonic acid residue with 6 carbon atoms, which is optionally substituted once or several times by halogen, C.sub.1 -C.sub.4 alkyl residues, C.sub.1 -C.sub.4 alkoxy residues, nitro and/or cyano, or represents an aliphatic carboxylic acid residue or a sulphonic acid residue with 1-4 carbon atoms, a carbonic acid residue, a thiocarbonic acid residue or a phosphoric acid residue which, corresponding to the numerical value of y, contains 0-2 phenoxy residues or C.sub.1 -C.sub.4 alkoxy residues optionally substituted with C.sub.1 -C.sub.4 alkyl or halogen,R.sup.2 represents R.sup.1, or hydrogen, a C.sub.1 -C.sub.4 alkyl residue, a C.sub.5 -C.sub.

Abstract: Sulphenamides are obtained by reacting N-chlorothiophthalimide with compounds containing one or two olefinic double bonds. These products retard vulcanization of natural or synthetic rubber.