Aqueous compositions for whitening and shading in coating applications

Abstract

The instant invention relates to aqueous coating compositions for optical brightening and shading of substrates.

1 . An aqueous coating composition for optical brightening and shading of a substrate, comprising
 (a) at least one optical brightener of formula (I)   
       
         
           
           
               
               
           
         
         in which the anionic charge on the brightener is balanced by a cationic charge comprising one or more identical or different cations selected from the group consisting of hydrogen, an alkali metal cation, alkaline earth metal, ammonium, ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or branched alkyl radical, ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or branched hydroxyalkyl radical, ammonium which is, di-, tri- or tetrasubstituted by a mixture of C 1 -C 4  linear or branched alkylradical and linear or branched hydroxyalkyl radical or mixtures thereof, 
         R 1  and R 1  may be the same or different, and each is hydrogen, C 1 -C 4  linear or branched alkyl, C 2 -C 4  linear or branched hydroxyalkyl, CH 2 CO 2 , CH 2 CH 2 CONH 2  or CH 2 CH 2 CN, 
         R 2  and R 2  may be the same or different, and each is C 1 -C 4  linear or branched alkyl, C 2 -C 4  linear or branched hydroxyalkyl, CH 2 CO 2 , CH(CO 2 )CH 2 CO 2 , CH(CO 2 )CH 2 CH 2 CO 2 , CH 2 CH 2 SO 3 , CH 2 CH 2 CO 2 , CH 2 CH(CH 3 )CO 2 , benzyl, or 
         R 1  and R 2  and/or R 1  and R 2 , together with the neighboring nitrogen atom signify a morpholine ring and 
         p is 1 or 2, 
         (b) at least one shading dye of formula (II) 
       
       
         
           
           
               
               
           
         
         in which 
         R 3  signifies H, methyl or ethyl, 
         R 4  signifies paramethoxyphenyl, methyl or ethyl, 
         M signifies a cation selected from the group consisting of hydrogen, an alkali metal cation, alkaline earth metal, ammonium, ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or branched alkyl radical, ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or
 branched hydroxyalkyl radical, ammonium which is, di-, tri- or tetrasubstituted by a mixture of C 1 -C 4  linear or branched alkylradical and linear or branched hydroxyalkyl radical or mixtures thereof, 
 
         (c) at least one white pigment, 
         (d) at least one primary binder, 
         (e) optionally one or more secondary binders and 
         (f) water. 
       
     
     
         2 . Aqueous coating composition according to  claim 1 , wherein in a compound of formula (I) for which p is 1, the CO 2  group is in the 2 or 4-position of the phenyl ring. 
     
     
         3 . Aqueous coating composition according to  claim 1 , wherein in a compound of formula (1) the anionic charge on the brightener is balanced by a cationic charge composed of one or more identical or different cations selected from the group consisting of hydrogen, an alkali metal cation, alkaline earth metal, ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or branched hydroxyalkyl radical, ammonium which is, di-, tri- or tetrasubstituted by a mixture of C 1 -C 4  linear or branched alkylradical and linear or branched hydroxyalkyl radical or mixtures thereof,
 R 1  and R 1  may be the same or different, and each is hydrogen, C 1 -C 4  linear or branched alkyl, C 2 -C 4  linear or branched hydroxyalkyl, CH 2 CO 2 , CH 2 CH 2 CONH 2  or CH 2 CH 2 CN,   R 2  and R 2  may be the same or different, and each is C 1 -C 4  linear or branched alkyl, C 2 -C 4  linear or branched hydroxyalkyl, CH 2 C0 2 , CH(CO 2 )CH 2 CO 2  or CH 2 CH 2 S0 3  and P is 1 or 2.   
     
     
         4 . An aqueous coating composition according to  claim 1 , wherein in compounds of formula (I), the anionic charge on the brightener is balanced by a cationic charge comprising one or more identical or different cations selected from the group consisting of Li + , Na + , K + , Ca 2+ , Mg + , ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or branched hydroxyalkyl radical, ammonium which is, di-, tri- or tetrasubstituted by a mixture of C 1 -C 4  linear or branched alkylradical and linear or branched hydroxyalkyl radical or mixtures thereof,
 R 1  and R 1  may be the same or different, and each is hydrogen, methyl, ethyl, propyl, α-methylpropyl, β-methylpropyl, β-hydroxyethyl, β-hydroxypropyl, CH 2 CO 2 , CH 2 CH 2 CONH 2  or CH 2 CH 2 CN,   R 2  and R 2  may be the same or different, and each is methyl, ethyl, propyl, α-methylpropyl, β-methylpropyl, β-hydroxyethyl, β-hydroxypropyl, CH 2 CO 2 , CH(CO 2 )CH 2 CO 2  or CH 2 CH 2 S0 3  and p is 1 or 2.   
     
     
         5 . Aqueous coating composition according to  claim 1 , wherein in a compound of formula (I), the anionic charge on the brightener is balanced by a cationic charge comprising one or more identical or different cations selected from the group consisting of Na t , K t , triethanolammonium, N-hydroxyethyl-N,Ndimethylammonium, N-hydroxyethyl-N,N-diethylammonium or mixtures thereof,
 R 1  and R 1  may be the same or different, and each is hydrogen, methyl, ethyl, propyl, β-hydroxyethyl, β-hydroxypropyl, CH 2 CO 2 , CH 2 CH 2 CONH 2  or CH 2 CH 2 CN,   R 2  and R 2  may be the same or different, and each is ethyl, propyl, hydroxyethyl, β-hydroxypropyl, CH 2 CO 2 , CH(CO 2 )CH 2 CO 2  or CH 2 CH 2 SO 3  and p is 1.   
     
     
         6 . Aqueous coating composition according to  claim 1 , wherein the compound of formula (I) is present in an amount of from 0.01 to 5% by weight, % by weight being based on the total weight of said white pigment. 
     
     
         7 . Aqueous coating composition according to  claim 1 , wherein in a compound of formula (II)
 R 3  signifies H, methyl or ethyl,   R 4  signifies paramethoxyphenyl, methyl or ethyl,   M signifies a cation selected from the group consisting of hydrogen, an alkali   metal cation, alkaline earth metal, ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or branched hydroxyalkyl radical,   ammonium which is, di-, tri- or tetrasubstituted by a mixture of C 1 -C 4  linear or branched alkylradical and linear or branched hydroxyalkyl radical or mixtures thereof.   
     
     
         8 . Aqueous coating composition according to  claim 1 , wherein in a compound of formula (II)
 R 3  signifies methyl or ethyl,   R 4  signifies methyl or ethyl,   M signifies a cation selected from the group consisting of Li + , Na + , K + , K + , ½ Ca 2+ , ½ Mg 2+ , ammonium which is mono-, di-, tri- or tetrasubstituted by a C 1 -C 4  linear or branched hydroxyalkyl radical, ammonium which is, di-, tri- or tetrasubstituted by a mixture of C 1 -C 4  linear or branched alkylradical and linear or branched hydroxyalkyl radical or mixtures thereof.   
     
     
         9 . Aqueous coating composition according to  claim 1 , wherein in a compound of formula (II)
 R 3  signifies methyl or ethyl,   R 4  signifies methyl or ethyl,   M signifies a cation selected from the group consisting of Na + , K + , triethanolammonium, N-hydroxyethyl-N,N-dimethylammonium, N-hydroxyethyl-N,N-diethylammonium or mixtures thereof.   
     
     
         10 . Aqueous coating composition according to  claim 1 , wherein the compound of formula (II) is used in an amount from 0.00001 to 0.05% by weight, the % by weight being based on the total weight of said white pigment. 
     
     
         11 . Aqueous coating composition according to  claim 1 , wherein the coating composition comprises from 10 to 70% by weight of white pigment, the % by weight being based on the total weight of the coating composition. 
     
     
         12 . Aqueous coating composition according to  claim 11 , wherein the white pigment comprises an inorganic pigment. 
     
     
         13 . Aqueous coating composition according to at least  claim 11 , wherein the binder comprises a single binder or of a mixture of primary and/or secondary binders. 
     
     
         14 . Aqueous coating composition according to  claim 13 , wherein the single or primary binder is used in an amount in a range of from 2 to 25% by weight, the % by weight being based on the total weight of white pigment. 
     
     
         15 . Aqueous coating composition according to  claim 13 , wherein polyvinyl alcohol is used as secondary binder, which has a degree of hydrolysis greater than or equal to 60% and a Brookfield viscosity of from 2 to 80 mPa·s (4% aqueous solution at 20° C.). 
     
     
         16 . Aqueous coating composition according to  claim 13 , wherein the secondary binder is used in an amount in a range of from 0.1 to 20% by weight, the % by weight being based on the total weight of white pigment. 
     
     
         17 . Aqueous coating composition according to  claim 1 , wherein the pH value of the coating composition is in a range of from 5 to 13. 
     
     
         18 . An aqueous coating composition according to  claim 1 , capable of being used for optical brightening and tinting of a paper substrate. 
     
     
         19 . An aqueous coating composition according to  claim 18 , capable of being used as a preformed aqueous solution, and the concentration of compound of formula (I) in water is optionally from 1 to 80% by weight, the % by weight being based on the total weight of the preformed aqueous solution comprising the compound of formula (I). 
     
     
         20 . An aqueous coating composition according to  claim 19 , wherein in the preformed aqueous solution, the concentration of compound of formula (II) in water is optionally of from 0.001 to 30% by weight, the % by weight being based on the total weight of the preformed aqueous solution comprising the compound of formula (II). 
     
     
         21 . An aqueous coating composition according
 to  claim 19 , wherein in the preformed aqueous solution, the concentration of secondary binders in water is from 1 to 50% by weight, the % by weight being based on the total weight of the preformed aqueous solution comprising the secondary binders.