Use of Micronized Cellulose and Fluorescent Whitening Agent for Surface Treatment of Cellulosic Materials

Abstract

A combination of micronized cellulose and fluorescent whitening agents for surface treatment of cellulosic sheet-formed materials, e.g. paper, board or cotton fabric, and to preparations including the micronized cellulose and the fluorescent whitening agents. The combination enables improved fluorescent whitening and optical brightening of the cellulosic materials.

1 . A process comprising:
 surface treating a cellulosic sheet-formed structures with a preparation comprising a micronized cellulose having a medium fiber length and medium particle size, respectively, below or equal to 15 μm, and at least one fluorescent whitening agent (FWA) having the formula (1)   
       
         
           
           
               
               
           
         
       
       wherein 
       R 1  and R 2  independently of each other mean H, SO 3   −  or COOH, with the proviso that, if R 1  is COOH, R 2  is H, and vice versa; 
       R 3  and R 5  independently of each other mean H, C 1 -C 4 -alkyl, C 2 -C 3 -hydroxyalkyl, CH 2 COO − , CH 2 CH 2 CN, CH 2 CH 2 CONH 2  or CH 2 CH 2 SO 3   − ; 
       R 4  and R 6  independently of each other mean H, C 1 -C 4 -alkyl, C 2 -C 3 -hydroxyalkyl, CH 2 COO − , CH 2 CH 2 SO 3   − , CH(COO − )CH 2 COO − , CH(COO − )CH 2 CH 2 COO −  or CH 2 -phenyl; or 
       R 3  and R 4 , or R 5  and R 6 , independently of each other together with the nitrogen atom form a morpholine ring; and wherein 
       M represents the corresponding charge equivalent selected from H + , an alkali metal cation, ammonium, C 1 -C 4 -tetraalkyl ammonium, ammonium which is mono-, di-, tri- or tetra-substituted by C 2 -C 3 -hydroxyalkyl radicals, and NH(R 7 ) n (R 8 ) m   + , with R 7  being C 1 -C 4 -alkyl and R 8  being C 2 -C 3 -hydroxyalkyl, wherein both n and m are an integer of 1 or 2 and n≠m;
 as well as mixtures thereof. 
 
     
     
         2 . The process according to  claim 1 , wherein the preparation further comprises water. 
     
     
         3 . The process according to  claim 2 , wherein the preparation is a size press liquor or a film press liquor. 
     
     
         4 . The process according to  claim 2 , wherein the preparation is a coating color and coating slip, respectively. 
     
     
         5 . The process according to  claim 1 , wherein the micronized cellulose comprises particles and/or fibers having a length of 0.005 μm to 15 μm and a maximum diameter that does not exceed 25 μm. 
     
     
         6 . The process according to  claim 1 , wherein in formula (1) of the at least one fluorescent whitening agent one group of R 1  and R 2  is H and the other group is selected from SO 3   −  and COOH. 
     
     
         7 . The process according to  claim 1 , wherein the cellulosic sheet-formed structure is paper or board. 
     
     
         8 . The process according to  claim 1 , wherein the cellulosic sheet-formed structure is textile material, in particular cotton fabric. 
     
     
         9 . A preparation for surface whitening treatment sheet-formed cellulose-containing structures, wherein the preparation comprises
 micronized cellulose comprising fibers and/or particles having a fiber length and particle size, respectively, below or equal to 15 μm; and   at least one fluorescent whitening agent (FWA) having the formula (1)   
       
         
           
           
               
               
           
         
       
       wherein 
       R 1  and R 2  independently of each other mean H, SO 3   −  or COOH, with the proviso that, if R 1  is COOH, R 2  is H, and vice versa; 
       R 3  and R 5  independently of each other mean H, C 1 -C 4 -alkyl, C 2 -C 3 -hydroxyalkyl, CH 2 COO − , CH 2 CH 2 CN, CH 2 CH 2 CONH 2  or CH 2 CH 2 SO 3   − ; 
       R 4  and R 6  independently of each other mean H, C 1 -C 4 -alkyl, C 2 -C 3 -hydroxyalkyl, CH 2 COO − , CH 2 CH 2 SO 3   − , CH(COO − )CH 2 COO − , CH(COO − )CH 2 CH 2 COO −  or CH 2 -phenyl; or 
       R 3  and R 4 , or R 5  and R 6 , independently of each other together with the nitrogen atom form a morpholine ring; and wherein 
       M represents the corresponding charge equivalent selected from H + , an alkali metal cation, ammonium, C 1 -C 4 -tetraalkyl ammonium, ammonium which is mono-, di-, tri- or tetra-substituted by C 2 -C 3 -hydroxyalkyl radicals, and NH(R 7 ) n (R 8 ) m   + , with R 7  being C 1 -C 4 -alkyl and R 8  being C 2 -C 3 -hydroxyalkyl, wherein both n and m are an integer of 1 or 2 and n≠m. 
     
     
         10 . The preparation of  claim 9 , wherein, based on weight, the 1 amount of micronized cellulose is less than or equal to a tenfold amount of the fluorescent whitening agent. 
     
     
         11 . The preparation of  claim 9 , wherein the fluorescent whitening agent to micronized cellulose is at a weight ratio of 7:93 to 50:50 weight-%, based on the active substance content of the preparation 
     
     
         12 . The preparation of  claim 9 , wherein the preparation further comprises starch and is a size press liquor or a film press liquor. 
     
     
         13 . The preparation of  claim 9 , wherein the preparation further comprises a white pigment and is a coating color and coating slip, respectively. 
     
     
         14 . A process for surface whitening treatment of cellulosic sheet-formed structures, comprising treating the cellulosic sheet-formed structure with a preparation as defined in  claim 9 . 
     
     
         15 . A paper obtainable by the process according to  claim 14 .