Method for production of filler loaded surface enhanced pulp fibers
The present invention relates to a method for preparing loaded paper pulp for use in the manufacture of paper or paper board. At least one process stream containing a plurality of unrefined pulp fibers and at least one process stream of at least one filler are combined in a refiner to form a loaded paper pulp composition having a plurality of surface enhanced pulp fibers that are loaded with particles of the at least one filler.
1. A method of making a filler-loaded pulp composition, the method comprising:
introducing wood pulp fibers and a first plurality of filler particles into one or more mechanical refiners, each of the refiner(s) comprising a pair of refiner plates that each has:
a bar width that is less than or equal to 1.3 millimeters; and
a groove width that is less than or equal to 2.5 millimeters; and
refining the first filler particles and wood pulp fibers with the refiner(s) until the refiner(s) consume at least 300 kilowatt-hours per ton of the wood pulp fibers, wherein the refining is performed such that (i) in each of the refiner(s) the first filler particles and wood pulp fibers are refined together and (ii) at least one of the refiner(s) operates at a specific edge load that is between 0.10 and 0.30 Watt-seconds/meter.
2. The method of claim 1 , wherein the first filler particles comprise crystals of precipitated calcium carbonate (PCC).
3. The method of claim 2 , wherein an average particle size of the crystals of PCC is between 0.2 and 3.0 microns.
4. The method of claim 1 , wherein no binders or retention aids are included in the filler-loaded pulp composition.
5. The method of claim 1 , wherein the ratio of the wood pulp fibers to the first filler particles introduced into the refiner(s) is between 1:5 and 1:1.
6. The method of claim 1 , wherein the ratio of the wood pulp fibers to the first filler particles introduced into the refiner(s) is between 1:3 and 1:1.
7. The method of claim 1 , wherein refining the first filler particles and wood pulp fibers is performed such that the refined wood pulp fibers have a length-weighted average fiber length that is at least 0.3 millimeters and an average hydrodynamic specific surface area that is at least 10 square meters per gram.
8. The method of claim 7 , wherein refining the first filler particles and wood pulp fibers is performed such that the refined wood pulp fibers have a fiber count that is at least 12,000 fibers per milligram on an oven-dry basis.
9. The method of claim 7 , wherein refining the first filler particles and wood pulp fibers is performed such that the refined wood pulp fibers have a length weighted average fiber length that is at least 0.4 millimeters and an average hydrodynamic specific surface area that is at least 12 square meters per gram.
10. The method of claim 1 , wherein refining the first filler particles and wood pulp fibers is performed such that a length weighted average length of the refined wood pulp fibers is at least 60% of the original length weighted average length of the wood pulp fibers prior to refining.
11. The method of claim 10 , wherein refining the first filler particles and wood pulp fibers is performed such that an average hydrodynamic specific surface area of the refined wood pulp fibers is at least 4 times greater than the average hydrodynamic specific surface area of the wood pulp fibers prior to refining.
12. The method of claim 1 , wherein for at least one of the refiner(s), each of the refiner plates has a bar width that is less than or equal to 1.0 millimeters and a groove width that is less than or equal to 1.6 millimeters.
13. The method of claim 1 , wherein the wood pulp fibers comprise hardwood pulp fibers.
14. The method of claim 13 , wherein refining the first filler particles and wood pulp fibers is performed until the refiner(s) consume at least 400 kilowatt-hours per ton of the wood pulp fibers.
15. The method of claim 1 , wherein the wood pulp fibers comprise softwood pulp fibers.
16. The method of claim 1 , comprising combining the refined first filler particles and refined wood pulp fibers with a second plurality of filler particles.
17. The method of claim 16 , wherein the first and second filler particles comprise calcium carbonate, talc, clay, a silica-based pigment, and/or an aluminum-based pigment.
18. The method of claim 1 , where the first filler particles comprise calcium carbonate, talc, clay, a silica-based pigment, and/or an aluminum-based pigment.
19. The method of claim 1 , wherein refining the first filler particles and wood pulp fibers is performed until the refiner(s) consume between 400 and 1,800 kilowatt-hours per ton of the wood pulp fibers.