Basf Aktiengesellschaft

Juergen Kipper

Bernhard Albert

Karin H Beck

Gerhard Wagenblast

Christos Vamvakaris

Friedrich Closs

Walter Kurtz

Helmut Bellaire

Benno Sens

Rudolf Griebel

Andres C Espino

Use of compounds from the class of the phthalocyanines, naphthalocyanines, nickel dithiolene complexes, aminium compounds of aromatic amines, methine dyes or azulenesquaric acid dyes which have their absorption maximum in the range from 600 to 1,200 nm and/or a fluorescence maximum in the range from 620 to 1,200 nm, as markers for liquids, a process for detecting markers in liquids, and a detector suitable for this purpose.

Use of compounds which absorb and/or fluoresce in the IR region as

Preparation of naphthalocyanines

Ink-ribbons comprising IR-absorbing compounds

Naphthalocyanines of the general formula I ##STR1## where the variables have the following meanings: R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are each independently of the others hydrogen, hydroxyl or C.sub.1 -C.sub.20 -alkyl or C.sub.1 -C.sub.20 -alkoxy, whose carbon chains may each be interrupted by from 1 to 4 oxygen atoms in ether function and which may be phenyl-substituted,

Naphthalocyanines

A liquid useful as printing ink contains one or more dyes with their absorption maximum within the range from 700 to 1200 nm selected from the phthalocyanines, the naphthalocyanines, the nickel-dithiolene complexes, the aminium compounds of aromatic amines, the methine dyes or the azulenesquaric acid dyes, as well as solvent and binder.

Use of a liquid containing IR dyes as printing ink

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Karlsruhe, Germany

Juergen Kipper