Method for fiber loading a chemical compound

Abstract

The present invention relates to a method for loading a chemical compound within the fibers of a fibrous material and to the fibrous materials produced by the method. In the method, a fibrous cellulose material is provided which consists of a plurality of elongated fibers having a fiber wall surrounding a hollow interior. The fibrous material has a moisture content such that the level of water ranges from 40-95% of the weight of the fibrous material and the water is positioned substantially within the hollow interior of the fibers and within the fiber walls of the fibers. A chemical is added to the fibrous material in a manner such that the chemical is disposed in the water present in the fibrous material. The fibrous material is then contacted with a gas which is reactive with the chemical to form a water insoluble chemical compound. The method provides a fibrous material having a chemical compound loaded within the hollow interiors and within the fiber walls of the plurality of fibers.

We claim: 
     
       1. A method for loading cellulosic fibers with calcium carbonate comprising: (a) providing a cellulosic fibrous material comprising a plurality of elongated fibers having a fiber wall surrounding a hollow-interior, said fibrous material having moisture present at a level sufficient to provide said cellulosic fibrous material in the form of dewatered crumb pulp;   (b) adding a chemical selected from the group consisting of calcium oxide and calcium hydroxide to said pulp in a manner such that at least some of said chemical becomes associated with the water present in said pulp; and   (c) contacting said cellulosic fibrous material with carbon dioxide while subjecting said cellulosic fibrous material to .[.higher.]. .Iadd.high .Iaddend.shear mixing so as to provide a cellulosic fibrous material having a substantial amount of calcium carbonate loaded within the hollow interior and within the fiber walls of the plurality of cellulosic fibers.   
     
     
       2. A method in accordance with claim 1 wherein the moisture content of said fibrous material is from about 40% to about 95% by weight. 
     
     
       3. A method in accordance with claim 1 wherein said chemical is added at a level of from about 0.1% to about 50% by weight based on the dry weight of said fibrous material. 
     
     
       4. A method in accordance with claim 1 wherein said chemical is added at a level of from about 5% to about 20% by weight based on the dry weight of said fibrous cellulose material. 
     
     
       5. A method in accordance with claim 1 wherein said contact with carbon dioxide is effected in a closed container pressurized with carbon dioxide gas. 
     
     
       6. A method in accordance with claim 5 wherein said carbon dioxide gas pressure is from about 5 psig to about 60 psig. 
     
     
       7. A method in accordance with claim 5 wherein said carbon dioxide is maintained in contact with said pulp for a period of from about 1 minute to about 60 minutes. 
     
     
       8. A method in accordance with claim 1 wherein said high shear mixing is sufficient to impart from about 10 to about 70 watt hours of energy per kilo of fiber, dry weight basis. 
     
     
       9. A method in accordance with claim 1 wherein said .[.higher.]. .Iadd.high .Iaddend.shear mixing is effected by means of a pressurized paper refiner. 
     
     
       10. A method in accordance with claim 9 wherein said refiner is provided with devil's tooth refining blades. 
     
     
       11. A method for making a filled paper from cellulose fibers having tubular walls and lumens which contain precipitated calcium carbonate comprising: (a) providing cellulose fibers containing water;   (b) adding a chemical selected from the group consisting of calcium hydroxide and calcium oxide to the cellulose fibers;   (c) contacting said fibers with carbon dioxide gas while subjecting said fibers to high shear mixing so that there is a reaction with the chemical to form precipitated calcium carbonate both in the interior of the fibers and in the fiber walls; and   (d) forming paper from said fibers.   
     
     
       12. A method in accordance with claim 11 wherein the water is present at a level of from about 40% to about 95% based on the dry weight of said cellulose fibers. 
     
     
       13. A method in accordance with claim 11 wherein said chemical is added at a level of from about 0.1% to about 50% by weight based on the dry weight of said cellulose fibers. 
     
     
       14. A method in accordance with claim 11 wherein said chemical is added at a level of from about 5% to about 20% by weight based on the dry weight of said cellulose fibers. 
     
     
       15. A method in accordance with claim 11 wherein said contact with carbon dioxide is effected in a closed container pressurized with carbon dioxide gas. 
     
     
       16. A method in accordance with claim 15 wherein said carbon dioxide gas pressure is from about 5 psig to about 60 psig. 
     
     
       17. A method in accordance with claim 15 wherein said carbon dioxide is maintained in contact with said pulp for a period of from about .[.10 minutes.]. .Iadd.1 minute .Iaddend.to about 60 minutes. 
     
     
       18. A method in accordance with claim 11 wherein said high shear mixing is sufficient to impart from about 10 to about 70 watt hours of energy per kilo of fiber, dry weight basis. 
     
     
       19. A method in accordance with claim 11 wherein said high shear mixing is effected by means of a pressurized paper refiner. 
     
     
       20. A method in accordance with claim 19 wherein said refiner is provided with devil's tooth refining blades. .Iadd. 
     
     
       21.  A method for loading cellulosic fibers with calcium carbonate comprising: (a) Providing a cellulosic fibrous material comprising a plurality of elongated fibers having a fiber wall surrounding a hollow interior, said fibrous material containing from about 40% to about 85% moisture, and having the form of dewatered crumb pulp;   (b) adding a chemical selected from the group consisting of calcium oxide and calcium hydroxide to said pulp in a manner such that at least some of said chemical becomes associated with the water present in the hollow interior of said pulp said chemical being added at a level of from about 0.1% to about 50% by weight based on the dry weight of said fibrous material; and   (c) contacting said cellulosic fibrous material with carbon dioxide so as to provide a cellulosic fibrous material having a substantial amount of calcium carbonate loaded within the hollow interior and within the fiber walls of the plurality of cellulosic fibers, said contact with said carbon dioxide being effected in a closed container pressurized with carbon dioxide gas. .Iaddend..Iadd.22. A method in accordance with claim 21 wherein said chemical is added at a level of from about 5% to about 20% by weight based on the dry weight of said fibrous cellulose material.   
     
     
        .Iaddend..Iadd.23.  A method in accordance with claim 21 wherein said carbon dioxide gas pressure is from about 5 psig to about 60 psig. .Iaddend..Iadd.24. A method in accordance with claim 21 wherein said carbon dioxide is maintained in contact with said pulp for a period of from about 1 minute to about 60 minutes. .Iaddend..Iadd.25. A method in accordance with claim 21 wherein said contact with carbon dioxide is effected while subjecting said cellulosic material to low shear mixing. .Iaddend..Iadd.26. A method in accordance with claim 21 wherein said cellulosic fibrous material is subjected to high shear mixing after contacting with carbon dioxide. .Iaddend..Iadd.27. A method in accordance with claim 26 wherein said high sheer mixing is sufficient to impart from about 10 to about 70 watt hours of energy per kilo of fiber, dry weight basis. .Iaddend..Iadd.28. A method in accordance with claims 26 wherein said high sheer mixing is effected by means of a pressurized paper refiner. .Iaddend..Iadd.29. A method in accordance with claim 28 wherein said refiner is provided with devil's tooth refining blades. .Iaddend..Iadd.30. A method for making a filler paper from cellulose fibers having tubular walls and lumens which contain precipitated calcium carbonate comprising: (a) providing cellulose fibers containing from about 40% to about 85% moisture;   (b) adding a chemical selected from the group consisting of calcium hydroxide and calcium oxide to the cellulose fibers said chemical being added at a level of from about 0.1% to about 50% by weight based on the dry weight of said fibrous material;   (c) contacting said fibers with carbon dioxide gas so that there is a reaction with the chemical to form precipitated calcium carbonate in the interior of the fibers, in the fiber walls, and on the surface of the fibers, said contact with said carbon dioxide being effected in a closed container pressurized with carbon dioxide gas; and   
     
     
       (d) forming paper from said fibers. .Iaddend..Iadd.31.  A method in accordance with claim 30 wherein said chemical is added at a level of from about 5% to about 20% by weight based on the dry weight of said cellulose fibers. .Iaddend..Iadd.32. A method in accordance with claim 30 wherein said carbon dioxide gas pressure is from about 5 psig to about 60 psig. .Iaddend..Iadd.33. A method in accordance with claim 30 wherein said carbon dioxide is maintained in contact with said pulp for a period of 
     
     
        from about 1 minute to about 60 minutes. .Iaddend..Iadd.34.  A method in accordance with claim 30 wherein said contact with carbon dioxide is effected while subjecting said cellulosic material to low shear mixing. .Iaddend..Iadd.35. A method in accordance with claim 30 wherein said cellulosic fibrous material is subjected to high shear mixing after contacting with carbon dioxide. .Iaddend..Iadd.36. A method in accordance with claims 35 wherein said high shear mixing is sufficient to impart from about 10 to about 70 watt hours of energy per kilo of fiber, dry weight basis. .Iaddend..Iadd.37. A method in accordance with claims 35 wherein said high shear mixing is effected by means of a pressurized paper refiner. .Iaddend..Iadd.38. A method in accordance with claim 37 wherein said refiner is provided with devil's tooth refining blades. .Iaddend.