Surface enhanced pulp fibers at a substrate surface
View Patent ↗The present invention relates to a method of making a paper product having improved printing characteristics. This is achieved by forming a fibrous substrate, and applying a surface treatment which comprises an aqueous composition. Notably, the aqueous composition includes surface enhanced pulp fibers, with the placement of the surface enhanced pulp fibers optimizing their functionality, with surface placement by use of a paper machine size press desirably facilitating a reduction in the typical starch usage. The present method comprising the steps of providing a aqueous slurry comprising a blend of cellulosic fibers and water and dewatering the aqueous slurry of cellulosic fibers and water to form a fibrous substrate. The present method further includes applying a surface treatment to the fibrous substrate, wherein the surface treatment comprises an aqueous composition including surface enhanced pulp fibers, to form a treated fibrous substrate, and thereafter drying the treated fibrous substrate to form a paper product having enhanced printing characteristics.
1. A method of making a paper product having improved printed characteristics, comprising the steps of:
providing an aqueous slurry comprising a blend of cellulosic fibers and water;
at least partially dewatering the aqueous slurry of cellulosic fibers and water to form a fibrous substrate;
applying a surface treatment to a top surface of the fibrous substrate, wherein the surface treatment comprises an aqueous composition comprising surface enhanced pulp fibers, to form a treated fibrous substrate, wherein the surface treatment is integrally coupled to the top surface of the fibrous substrate; and
drying the treated fibrous substrate to form a paper product having enhanced printing characteristics,
wherein the surface enhanced pulp fibers comprise refined hardwood pulp fibers having a length-weighted average fiber length of at least about 0.3 millimeters, and an average hydrodynamic specific surface area of at least about 10 square meters per gram.
2. The method of claim 1 , wherein the surface treatment comprises a blend of surface enhanced pulp fibers and at least one of: a starch composition; a pigmentation composition; and a surface coating formulation.
3. The method of claim 2 , wherein the surface treatment comprises an ethylated starch solution having between about 0.25% to 1.0%, by weight, of the surface enhanced wood pulp fiber.
4. The method of claim 3 , wherein the ethylated starch solution comprises from about 1.0% to 12%, by weight, of starch solids.
5. The method of claim 3 , wherein the ethylated starch solution comprises has a viscosity of about 10 to 220 centipoise.
6. The method of claim 2 , wherein the surface treatment comprises a 7.0% ethylated starch/0.5% surface enhanced wood pulp fibers solution by weight, and wherein the paper product has a greater than 2 points opacity increase.
7. The method of claim 1 , wherein the applying step comprises applying the surface treatment by the use of at least one of: a two-roll size press; a rod-metering size press; a blade coater; a fountain coater; a cascade coater; and a spray applicator.
8. The method of claim 1 , further comprising screening the surface enhanced wood pulp fibers prior to the applying step to remove relatively larger fiber fragments to enhance printing characteristics.
9. The method of claim 1 , wherein during the applying step, the surface treatment is applied to the fibrous substrate to provide coverage of gaps existing in the underlying fibrous substrate.
10. The method of claim 1 , wherein prior to the applying step, further comprising chemically reacting the surface enhanced pulp fibers with a composition to enhance ink jet printing characteristics of the paper product.
11. The method of claim 1 , further comprising refining the hardwood pulp to an energy input of approximately 400-1,800 kilowatt-hours/ton to form the surface enhanced pulp fibers.
12. The method of claim 1 , wherein the number of surface enhanced pulp fibers is at least 12,000 fibers/milligram on an oven-dry basis.
13. The method of claim 1 , wherein the surface enhanced pulp fiber has a length-weighted average fiber length that is at least 60% of the length-weighted average length of the fibers prior surface enhancement by fibrillation, and an average hydrodynamic specific surface area that is at least 4 times greater than the average specific surface area of the fibers prior to fibrillation.
14. The method of claim 13 , wherein the surface enhanced pulp fibers are refined with an energy input of at least about 300 kilowatt-hours/ton.
15. The method of claim 1 , wherein the surface enhanced pulp fibers function as a sizing agent to close up the top surface of the fibrous substrate.
16. A paper product having improved printed characteristics, comprising:
a fibrous substrate having a top surface;
a surface treatment configured to provide coverage of gaps existing in the underlying fibrous substrate, the surface treatment comprises a layer of surface enhanced pulp fibers and a starch composition comprising an ethylated starch solution having between about 0.25% to 1.0%, by weight, of the surface enhanced wood pulp fibers, wherein the surface treatment is integrally coupled to the top surface of the fibrous substrate,
wherein the surface enhanced pulp fibers comprise refined hardwood pulp fibers having a length-weighted average fiber length of at least about 0.3 millimeters, and an average hydrodynamic specific surface area of at least about 10 square meters per gram.
17. The paper product of claim 16 , wherein the surface treatment further comprises at least one of: a pigmentation composition; and a surface coating formulation.
18. The paper product of claim 16 , wherein the ethylated starch solution comprises from about 1.0% to 12%, by weight, of starch solids, and wherein the ethylated starch solution comprises has a viscosity of about 10 to 220 centipoise.
19. The paper product of claim 16 , wherein hardwood pulp is refined to an energy input of approximately 400-1,800 kilowatt-hours/ton to form the surface enhanced pulp fibers.
20. The paper product of claim 16 , wherein the number of surface enhanced pulp fibers is at least 12,000 fibers/milligram on an oven-dry basis.
21. The paper product of claim 16 , wherein the surface enhanced pulp fiber has a length-weighted average fiber length that is at least 60% of the length-weighted average length of the fibers prior surface enhancement by fibrillation, and an average hydrodynamic specific surface area that is at least 4 times greater than the average specific surface area of the fibers prior to fibrillation.
22. The paper product of claim 16 , wherein the surface enhanced pulp fibers function as a sizing agent to close up the top surface of the fibrous substrate.
23. The paper product of claim 16 , wherein the surface treatment comprises a 7.0% ethylated starch/0.5% surface enhanced wood pulp fibers solution by weight, and wherein the paper product has a greater than 2 points opacity increase.