Transparent and/or translucent fluorescent color paper

Abstract

The invention relates to a paper including at least a fluorescent pigment and which presents the following physical characteristics: it is transparent and/or translucent, it has an intensity of color (or saturation) c and a luminosity L, measured in CIELAB units in accordance with standard DIN 53237, such that the ratio of c to L is greater than 50%, it has, for a given wavelength λmax, a coefficient of reflection ΔR greater than 100%, as measured on a paper placed on a white base, as well as a preparation process for such a paper.

1 . Paper characterized in that it that it includes at least a fluorescent pigment and presents the following physical characteristics: 
 it is transparent and/or translucent,    it has an intensity of color (or saturation) c and a luminosity L, measured in CIELAB units in accordance with standard DIN 53237, such that the ratio of c to L is greater than 50%,    it has, for a given wavelength λmax, a coefficient of reflection ΔR greater than 100%, as measured on a paper placed on a white base.    
     
     
         2 . Paper according to  claim 1 , characterized in that consists of a transparent paper which includes, on at least one of its two sides, a surface coat of fluorescent pigment insoluble in water.  
     
     
         3 . Paper according to  claim 2 , characterized in that it includes a coat of fluorescent pigment insoluble in water on each of its sides.  
     
     
         4 . Paper according to one of claims  2  and  3 , characterized in that the surface coat on each side comprises, expressed as dry weight, from  1  to 10 g/m 2 , preferably from 3 to 6 g/m 2  of fluorescent pigment.  
     
     
         5 . Paper according to  claim 1 , characterized in that it includes, in solid form, a fluorescent pigment in a quantity of 5 to 20% expressed as dry weight of pigment relative to the dry weight of paper.  
     
     
         6 . Paper according to any one of  claims 1  to  5 , characterized in that the transparent paper is chosen from among the group formed by the tracing paper obtained with cellulose fibers having a degree of Schöpper refinement greater than 80, a greaseproof paper, a “crystal” or “glassine” paper, a paper made transparent by chemical means or other paper made transparent by chemical and/or mechanical means.  
     
     
         7 . Paper according to any one of  claims 1  to  4 , and  6 , characterized in that it is obtained by deposition on a transparent paper of an aqueous composition containing a fluorescent pigment, in a quantity of about 20 to 30% expressed as wet weight.  
     
     
         8 . Paper according to  claim 7 , characterized in that it is obtained by deposition on a transparent paper of an aqueous composition including or not including a minute quantity of fillers.  
     
     
         9 . Paper according to any one of  claims 1  to  4 ,  6  and  7 , characterized in that it is obtained by deposition of an aqueous composition containing a fluorescent pigment by coating, heliographic, flexographic, offset or serigraphic printing.  
     
     
         10 . Application of a paper according to any one of  claims 1  to  9  to printing and/or writing.  
     
     
         11 . Production process for a translucent and/or transparent paper having an intense fluorescent color, characterized in that: 
 a cellulose or a paper is chosen which is treated so as to obtain a transparent and/or translucent paper;    a pigment of the desired wavelength is chosen, which is mixed with the cellulose or which is deposited on the surface of the paper resulting from the treatment of the cellulose.