Method for fiber loading a chemical compound

• US 5,223,090 A
• Filed: 12/11/1991
• Issued: 06/29/1993
• Est. Priority Date: 03/06/1991
• Status: Expired

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Department Of Agriculture
• Inventors: Tan, Freya, Klungness, John H., Caulfield, Daniel F., Sykes, Marguerite S., Shilts, Richard W., Sachs, Irving B.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/805,025
• Time in Patent Office: 566 Days
• Field of Search: 162/9, 162/181.2, 162/182, 162/183
• US Class Current: 162/9
• CPC Class Codes: D21C 9/004 inorganic compounds
• CPC Class Codes: D21H 17/00 Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
• CPC Class Codes: D21H 17/675 Oxides, hydroxides or carbonates
• CPC Class Codes: D21H 17/70 forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with other substances added separately
• CPC Class Codes: D21H 23/16 Addition before or during pulp beating or refining disintegrating fibrous raw materials in mills in the presence of chemical agents D21B1/16; methods of beating D21D1/02; methods of refining D21D1/20

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.

Claims

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 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 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 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.