Paper sizing composition, sized paper, and method for sizing paper

Abstract

Embodiments of the present invention provide a paper surface sizing composition, a paper web coated on one or more sides or surfaces with a paper surface sizing composition, and a method for treating one or more sides of the paper web with a paper surface sizing composition to impart benefits relating to one or more of the following properties: (1) brightness; (2) opacity; (3) paper smoothness; (4) print quality; (5) optionally ink dry time (e.g., for ink jet printing where the sizing composition has option); and (6) optionally minimizing or eliminating edge welding (e.g., for paper webs used in, for example, form printing).

What is claimed is: 
     
         1 . A composition comprising:
 an acicular calcium carbonate paper pigment having an aspect ratio in the range of from about 1.5 to about 15 and a low particulate surface area;   a paper starch binder; and   a paper co-binder;   wherein the starch comprises from about 30 to about 99%% by weight of the total combined weight of the starch binder and the co-binder;   wherein the co-binder comprises from about 1 to about 70% by weight of the total combined weight of starch and co-binder;   wherein the pigment to starch/co-binder weight ratio is in the range of from about 0.5 to about 4;   wherein the composition has a Brookfield viscosity in the range of from about 20 to about 500 centipoise;   wherein the composition has a solids content of at least about 8% by weight.   
     
     
         2 . The composition of  claim 1 , wherein the pigment has a particulate surface area of less than about 20 msg. 
     
     
         3 . The composition of  claim 2 , wherein the pigment has an aspect ratio in the range of from about 2 to about 12. 
     
     
         4 . The composition of  claim 3 , wherein the pigment has an aspect ratio in the range of from about 4 to about 10. 
     
     
         5 . The composition of  claim 2 , wherein the starch binder comprises from about 40 to about 95% by weight) of the total combined weight of the starch binder and the co-binder, and wherein the co-binder comprises from about 5 to about 60% by weight of the total combined weight of the starch binder and the co-binder. 
     
     
         6 . The composition of  claim 5 , wherein the starch binder comprises from about 50 to about 95% by weight) of the total combined weight of the starch binder and the co-binder, and wherein the co-binder comprises from about 5 to about 50% by weight of the total combined weight of the starch binder and the co-binder. 
     
     
         7 . The composition of  claim 2 , wherein the pigment to starch binder/co-binder weight ratio is in the range of from about 0.75 to about 3. 
     
     
         8 . The composition of  claim 7 , wherein the pigment to starch binder/co-binder weight ratio is in the range of from about 1 to about 3. 
     
     
         9 . The composition of  claim 2 , wherein the Brookfield viscosity is in the range of from about 30 to about 300 centipoise. 
     
     
         10 . The composition of  claim 2 , wherein the solids content is at least about 12% by weight. 
     
     
         11 . The composition of  claim 2 , wherein the starch binder comprises a natural starch, modified starch, a cationic starch, an amphoteric starch, a starch phosphate, a starch ether, a hydroxyalkylated starch, or a combination thereof. 
     
     
         12 . The composition of  claim 2 , wherein the co-binder comprises a polymer latex, a proteinaceous adhesive, a polyvinyl alcohol, or a combination thereof. 
     
     
         13 . An article comprising:
 a paper web having first and second surfaces; and   a paper surface size coating on at least one of the first and second surfaces,   wherein the paper surface size coating provides a paper surface size loading on each surface on which the paper surface size coating is present is in an amount from about 0.5 to about 4 gsm;   wherein the paper surface size coating comprises:
 an acicular calcium carbonate paper pigment having an aspect ratio in the range of from about 2 to about 12 and a low particulate surface area; 
 a paper starch binder; and 
 a paper co-binder; 
 wherein the starch binder comprises from about 40 to about 95% by weight of the total combined weight of the starch binder and the co-binder; 
 wherein the co-binder comprises from about 5 to about 60% by weight of the total combined weight of the starch binder and the co-binder; and 
 wherein the pigment to starch binder/co-binder weight ratio is in the range of from about 0.75 to about 3. 
   
     
     
         14 . The article of  claim 13 , wherein the paper surface size coating is on one of the first and second surfaces. 
     
     
         15 . The article of  claim 13 , wherein the paper surface size coating is on both of the first and second surfaces. 
     
     
         16 . The article of  claim 13 , wherein the a paper surface size loading on each surface on which the paper surface size coating is present is in an amount from about 1 to about 3 gsm. 
     
     
         17 . The article of  claim 13 , wherein the pigment has a particulate surface area of less than about 20 msg. 
     
     
         18 . The article of  claim 17 , wherein the pigment has an aspect ratio in the range of from about 4 to about 10. 
     
     
         19 . The article of  claim 17 , wherein the starch binder comprises from about 50 to about 95% by weight) of the total combined weight of the starch binder and the co-binder, and wherein the co-binder comprises from about 5 to about 50% by weight of the total combined weight of the starch binder and the co-binder. 
     
     
         20 . The article of  claim 17 , wherein the pigment to starch binder/co-binder weight ratio is in the range of from about 1 to about 3. 
     
     
         21 . The article of  claim 17 , wherein the starch binder comprises a natural starch, modified starch, a cationic starch, an amphoteric starch, a starch phosphate, a starch ether, a hydroxyalkylated starch, or a combination thereof. 
     
     
         22 . The article of  claim 21 , wherein the co-binder comprises a polymer latex, a proteinaceous adhesive, a polyvinyl alcohol, or a combination thereof. 
     
     
         23 . A method comprising the following steps:
 (a) providing an uncoated or a single-side coated paper web having first and second surfaces; and   (b) providing a liquid paper surface sizing composition comprising:
 an acicular calcium carbonate paper pigment having an aspect ratio in the range of from about 4 to about 10 and a low particulate surface area; 
 a paper starch binder; and 
 a paper co-binder; 
 wherein the starch binder comprises from about 50 to about 95% by weight of the total combined weight of starch and co-binder; 
 wherein the co-binder comprises from about 5 to about 50% by weight of the total combined weight of the starch binder and the co-binder; 
 wherein the pigment to starch binder/co-binder weight ratio is in the range of from about 1 to about 3; 
 wherein the composition has a Brookfield viscosity in the range of from about 30 to about 300 centipoise; 
 wherein the composition has a solids content of at least about 12% by weight; and 
   (c) treating at least one of the first and second surfaces of the paper web of step (a) with the paper surface size composition of step (b), wherein the paper surface size loading on each surface on which the paper surface size coating is present is in an amount from about 0.5 to about 4 gsm.   
     
     
         24 . The method of  claim 23 , wherein a single-side coated paper web is provided in step (a). 
     
     
         25 . The method of  claim 23 , wherein an uncoated paper web is provided in step (a). 
     
     
         26 . The method of  claim 23 , wherein the uncoated paper web is treated in step (c) with the composition of step (b) on one of the first and second surfaces. 
     
     
         27 . The method of  claim 23 , wherein the uncoated paper web is treated in step (c) with the composition of step (b) on both the first and second surfaces. 
     
     
         28 . The method of  claim 23 , wherein step (c) is carried out with a metering size press. 
     
     
         29 . The method of  claim 28 , wherein step (c) is carried out with a rod metering size press, a gated roll metering size press, or a doctor blade metering size press. 
     
     
         30 . The method of  claim 23 , wherein the paper surface size loading during step (c) on each surface on which the paper surface size coating is present is in an amount from about 1 to about 3 gsm. 
     
     
         31 . The method of  claim 23 , wherein the pigment has a particulate surface area of less than about 20 msg. 
     
     
         32 . The method of  claim 31 , wherein the composition of step (b) has solids content is at least about 12% by weight. 
     
     
         33 . The method of  claim 31 , wherein the pigment has an aspect ratio in the range of from about 4 to about 10. 
     
     
         34 . The method of  claim 31 , wherein the starch binder comprises from about 50 to about 95% by weight) of the total combined weight of the starch binder and the co-binder, and wherein the co-binder comprises from about 5 to about 50% by weight of the total combined weight of the starch binder and the co-binder. 
     
     
         35 . The method of  claim 31 , wherein the pigment to starch binder/co-binder weight ratio is in the range of from about 1 to about 3. 
     
     
         36 . The method of  claim 31 , wherein the composition of step (b) has a Brookfield viscosity in the range of from about 30 to about 300 centipoise. 
     
     
         37 . The method of  claim 31 , wherein the starch binder comprises a natural starch, modified starch, a cationic starch, an amphoteric starch, a starch phosphate, a starch ether, a hydroxyalkylated starch, or a combination thereof. 
     
     
         38 . The method of  claim 37 , wherein the co-binder comprises a polymer latex, a proteinaceous adhesive, a polyvinyl alcohol, or a combination thereof.