Method for producing cellulose filaments with less refining energy
A novel method is disclosed to make cellulose filaments (CF) from wood or other plant fibers with lower energy consumption. The method consists of multi-stage, high consistency refining, followed by low consistency refining or by low consistency, non-refining mechanical treatment, of wood or other plant fibers. The total specific refining energy for the multi-stage, high consistency refining is preferably 2,000-18,000 kWh/t, and more preferably 2,000-12,000 kWh/t. The CF produced can be used as a superior reinforcement additive in the production of paper, tissue or paperboard and in the production of plastic composites. It can also be used as a viscosity or rheology modifier in food products, coatings or drilling muds. The CF produced can also be used to make strong films for application in packaging and in composites.
1. A method of making cellulose filaments (CF) comprising:
providing a high consistency cellulose pulp with a consistency of 20 to 65 wt % solids;
a multi-pass high consistency refining of the high consistency cellulose pulp with a total specific refining energy (Energy HC ) of 2,000 to 18,000 kWh/t; to produce a refined cellulose material;
diluting the refined cellulose material to a low consistency of 0.1 to 6 wt % solids to produce a low consistency cellulose material;
a low consistency refining of the low consistency cellulose material with a total specific refining energy (Energy LC ) of 15 to 2,000 kWh/t; and
recovering the cellulose filaments having an aspect ratio of at least 200 to 5000 and a width of 30 nm to 500 nm from the refiner,
wherein the method has a combined total specific refining energy (Energy HC ) that is a sum of the total specific refining energy for the multi-pass high consistency refining plus the total specific refining energy for the low consistency refining (Energy HC +Energy LC ).
2. The method of claim 1 , wherein the total specific refining energy for the multi-pass, high consistency refining (Energy Hc ) is 2,000 to 12,000 kWh/t.
3. The method of claim 1 , wherein the total specific refining energy for the multi-pass, high consistency refining (Energy HC ) is 2,000 to 6,000 kWh/t.
4. The method of claim 1 , wherein the consistency for the multi-pass, high consistency refining is 25 to 40 wt % solids.
5. The method of claim 1 , wherein the consistency for the low consistency refining is 0.5 to 4 wt % solids.
6. The method of claim 1 , wherein the total specific refining energy for the low consistency refining (Energy LC ) is 15 to 1,200 kWh/t.
7. The method of claim 1 , wherein the total specific refining energy for the low consistency refining (Energy LC ) divided by the combined total specific refining energy (Energy C ) is an energy percentage of 0.08 to 50%.
8. The method of claim 7 , wherein the energy percentage is 1 to 40%.
9. The method of claim 7 , wherein the energy percentage is 2 to 30%.
10. The method of claim 7 , wherein the energy percentage is 2 to 20%.
11. The method of claim 1 , wherein the cellulose pulp is a softwood chemical pulp.
12. The method of claim 1 , wherein the refined cellulose material is diluted to a low consistency of 0.1 to 5 wt % solids.
13. The method of claim 1 , wherein the CF tensile strength increased per Energy LC is greater than that per Energy HC .