Flexographic printing ink for printing control marks

Abstract

A luminescent flexographic printing ink for printing control marks comprises a combination of a light-scattering pigment and an optical brightener and is not opaque. The luminescent flexographic printing ink is used for printing control marks and bar codes and for the production of decorative papers, wood laminates and floor panels.

We claim:  
     
         1 . A luminescent flexographic printing ink for printing control marks, at least comprising a solvent or a solvent mixture, at least one polymeric binder and optionally further additives, wherein the printing ink furthermore comprises at least one light-scattering pigment and at least one optical brightener in combination with one another, with the additional proviso that the printing ink is not opaque.  
     
     
         2 . A flexographic printing ink as claimed in  claim 1 , wherein the pigment is a white pigment.  
     
     
         3 . A flexographic printing ink as claimed in  claim 2 , wherein the white pigment is a TiO 2  pigment.  
     
     
         4 . A flexographic printing ink as claimed in any of  claims 1  to  3 , wherein the solvent is water or a predominantly aqueous solvent mixture.  
     
     
         5 . A flexographic printing ink as claimed in any of  claims 1  to  4 , wherein at least one of the polymeric binders is casein or a derivative thereof.  
     
     
         6 . The use of a flexographic printing ink as claimed in any of  claims 1  to  5  for printing control marks and bar codes.  
     
     
         7 . The use of a flexographic printing ink as claimed in any of  claims 1  to  5  for the production of decorative papers.  
     
     
         8 . The use of a flexographic printing ink as claimed in any of  claims 1  to  5  for the production of wood laminates and panels.  
     
     
         9 . A process for the production of panels, comprising the following steps: 
 (a) production of a decorative paper having printed-on control marks,    (b) processing of the decorative paper with impregnating resin to give wood laminates, and    (c) division of the wood laminates into panels by means of multiblade saws,    wherein a luminescent flexographic printing ink as claimed in any of claims  1 - 5  is used for printing the control marks, the saw apparatus being equipped with luminescence detectors and the saw table for aligning the saw cut being controled by the signals obtained.