US20220243402A1

US20220243402A1 - Method for manufacturing a coated cellulosic substrate and a coated cellulosic substrate

Info

Publication number: US20220243402A1
Application number: US17/588,270
Authority: US
Inventors: John D. Benson; Charles Casimir SIEGLING, III
Original assignee: WestRock Shared Services LLC
Current assignee: WestRock Shared Services LLC
Priority date: 2021-01-29
Filing date: 2022-01-29
Publication date: 2022-08-04
Also published as: CA3146960A1

Abstract

A method for manufacturing a coated cellulosic substrate including delivering a blended starch composition to a metering size press and applying a coating of the blended starch composition from the metering size press onto a cellulosic substrate. The blended starch composition includes a lipophobic starch having a shear-thinning rheology and a food grade starch.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Patent Application No. 63/143,112 filed n Jan. 29, 2021, the entire contents of which is incorporated herein by reference.

FIELD

The present application relates to the field of coated cellulosic substrates, particularly coated cellulosic substrates having oil and grease resistance.

BACKGROUND

Current treatments used for providing oil and grease resistance to cellulosic substrates include treatment with fluorocarbons or other per- and polyfluoroalkyl substances (PFAS). There is a desire in the industry for a non PFAS-based coating that provides sufficient oil and grease resistance for single service food applications.
Accordingly, those skilled in the art continue with research and development in the field of coated cellulosic substrates having oil and grease resistance.

SUMMARY

Disclosed are methods for manufacturing a coated cellulosic substrate.
In one example, the disclosed method for manufacturing a coated cellulosic substrate includes (1) delivering a blended starch composition to a metering size press and (2) applying a coating of the blended starch composition from the metering size press onto a cellulosic substrate. The blended starch composition includes a lipophobic starch having a shear-thinning rheology and a food grade starch.
In another example, the disclosed method for manufacturing a coated cellulosic substrate includes (1) delivering a blended starch composition to a metering size press, the blended starch composition including a lipophobic starch having a shear-thinning rheology and a food grade starch having a water fluidity in a range of from about 1 to about 80, wherein a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 20:80 to about 99:1, and wherein the blended starch composition has a solids content in a range of from about 17% to about 31%; and (2) applying a coating of the blended starch composition from the metering size press onto a cellulosic substrate to achieve a dry coat weight in a range of from about 1.0 g/m²to about 9.0 g/m², wherein the cellulosic substrate has a basis weight in a range of from about 16 to about 36 pounds per 1000 square feet and a Gurley porosity in a range of from about 5 seconds per 100 cubic centimeters to about 200 seconds per 100 cubic centimeters.
Also disclosed are coated cellulosic substrates.
In one example, the disclosed coated cellulosic substrate includes a cellulosic substrate and a blended starch coating on the cellulosic substrate. The blended starch coating includes a lipophobic starch and a food grade starch.
Other examples of the disclosed coated cellulosic substrates and methods for manufacturing coated cellulosic substrates will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an exemplary coated cellulosic substrate according to an aspect of the present description.

FIG. 2 is a cross-sectional view of an exemplary corrugated structure comprising the coated cellulosic substrate according to an aspect of the present description.

FIG. 3 is a cross-sectional view of an exemplary corrugated package comprising the coated cellulosic substrate according to an aspect of the present description.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of an exemplary coated cellulosic substrate according to an aspect of the present description.
According to the present description, a coated cellulosic substrate 10 has a cellulosic substrate 11 and a blended starch coating 12 on the cellulosic substrate. The blended starch coating includes a lipophobic starch having a shear-thinning rheology and a food grade starch. In one example, the food grade starch may be (or may include) a modified food grade starch. In another example, the food grade starch may be (or may include) an unmodified food grade starch.
The cellulosic substrate may be, for example, a paper-based substrate formed from any conventional paper typically used for production of paperboard products or packages. These include, but are not limited to, bleached board, unbleached board, coated bleached board, coated unbleached board, folding board, and recycled board. The paper-based substrate may be made from pulp fibers derived from hardwood trees, softwood trees, or a combination of hardwood and softwood trees prepared for use in a papermaking finish by any known suitable process. The fiber pulps may be bleached or unbleached. When desired, recycled pulp fibers may be used.
In one aspect, the cellulosic substrate may have a basis weight in a range of from about 16 to about 69 pounds per 1000 square feet. In another aspect, the cellulosic substrate may have a basis weight in a range of from about 21 to about 31 pounds per 1000 square feet. In yet another aspect, the cellulosic substrate may have a basis weight in a range of from about 24 to about 28 pounds per 1000 square feet. For example, the cellulosic substrate may have a basis weight of about 26 pounds per 1000 square feet.
In one aspect, the cellulosic substrate may have a Gurley porosity in a range of from 5 seconds per 100 cubic centimeters to 200 seconds per 100 cubic centimeters. In another aspect, the cellulosic substrate may have a Gurley porosity in a range of from 10 seconds per 100 cubic centimeters to 150 seconds per 100 cubic centimeters. In yet another aspect, the cellulosic substrate may have a Gurley porosity in a range of from 15 seconds per 100 cubic centimeters to 60 seconds per 100 cubic centimeters. The Gurley porosity is determined in accordance with TAPPI Test Method T 460.
For example, the cellulosic substrate may be a kraft based linerboard. In a specific example, the cellulosic substrate may be a kraft based linerboard having a basis weight of about 26 pounds per 1000 square feet and a Gurley porosity in a range of from 15 seconds per 100 cubic centimeters to 60 seconds per 100 cubic centimeters.
The blended starch coating is free from PFAS. Thus, the blended starch coating may be a non-PFAS blended starch coating that provides sufficient oil and grease resistance for single service food applications.
The lipophobic starch having a shear-thinning rheology provides the blended starch coating with sufficient oil and grease resistance for single service food applications. The shear-thinning rheology of the lipophobic starch allows the blended starch coating to become thinner as the blended starch coating is driven under high shear into a nip of a metering size press but then regain viscosity as blended starch coating flows away from the nip. This viscosity restoration resulting from the shear-thinning rheology of the lipophobic starch serves to reduce starch penetration into the paper to ensure that the lipophobic starch predominantly remains at the surface of the cellulosic substrate to ensure sufficient oil and grease resistance. Further, the lipophobic starch having a shear-thinning rheology is preferably suitable for contact with food, e.g., FDA approved. An exemplary lipophobic starch having a shear-thinning rheology is FILMKOTE 370 by Ingredion Incorporated, which is FDA approved.
The food grade starch provides the blended starch coating with sufficient runnability during the metering size press process. In one aspect, the food grade starch may have a water fluidity in a range of from about 1 to about 80. In another aspect, the food grade starch may have a water fluidity in a range of from about 5 to about 70. In yet another aspect, the food grade starch may have a water fluidity in a range of from about 10 to about 60. In yet another aspect, the food grade starch may have a water fluidity in a range of from about 15 to about 50. In yet another aspect, the food grade starch may have a water fluidity in a range of from about 19 to about 40. Thus, by providing the food grade starch to the blended starch coating, the blended starch coating is provided with sufficient runnability during the metering size press process. Furthermore, by selection of a starch derived from a food product, the food grade starch and resulting blended starch coating can be suitable for contact with food, e.g., FDA approved. The food grade starch can be made from a variety of foods. In an aspect, the food grade starch can be refined from waxy maize.
Water fluidity is an empirical test of viscosity measured on a scale of 0-90, wherein water fluidity is inversely proportional to viscosity. Water fluidity of starches is typically measured using a Thomas Rotational Shear-type Viscometer (commercially available from Arthur A. Thomas CO., Philadelphia, Pa.), standardized at 30° C. with a standard oil having a viscosity of 24.73 cps, which oil requires 23.12±0.05 sec for 100 revolutions. Accurate and reproducible measurements of water fluidity are obtained by determining the time that elapses for 100 revolutions at different solids levels depending on the starch's degree of conversion. As conversion increases, the viscosity decreases and the water fluidity values increase.
In one aspect, a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 1:99 to about 99:1. In another aspect, a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 30:70 to about 98:2. In yet another aspect, a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 40:60 to about 95:5. In yet another aspect, a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 50:50 to about 90:10. In yet another aspect, a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 60:40 to about 80:20. In yet another aspect, a weight ratio of the lipophobic starch to the food grade starch is in a range of about 70:30.
In an aspect, blended starch coating may further include other components. Preferably, the blended starch coating consists essentially of lipophobic starch and the food grade starch, and, thus, preferably does not include any additional component that material affect the basic and novel characteristics of the blended starch coating as explained above, which is sufficient oil and grease resistance for single service food applications as provided by the lipophobic starch having a shear-thinning rheology and sufficient runnability during the metering size press process as provided by the food grade starch.
In an aspect, the combined amount of lipophobic starch and food grade starch is at least about 50 percent of the blended starch coating. In another aspect, the combined amount of lipophobic starch and food grade starch is at least about 60 percent of the blended starch coating. In yet another aspect, the combined amount of lipophobic starch and food grade starch is at least about 70 percent of the blended starch coating. In yet another aspect, the combined amount of lipophobic starch and food grade starch is at least about 80 percent of the blended starch coating. In yet another aspect, the combined amount of lipophobic starch and food grade starch is at least about 90 percent of the blended starch coating. In yet another aspect, the combined amount of lipophobic starch and food grade starch is at least about 95 percent of the blended starch coating. In yet another aspect, the combined amount of lipophobic starch and food grade starch is at least about 98 percent of the blended starch coating. In yet another aspect, the combined amount of lipophobic starch and food grade starch is at least about 99 percent of the blended starch coating. In yet another aspect, the combined amount of lipophobic starch and food grade starch is about 100 percent of the blended starch coating.
In one aspect, the blended starch coating may have a dry coat weight in a range of from about 1.0 to about 10.0 grams per square meter (g/m²). In another aspect, the blended starch coating may have a dry coat weight in a range of from about 2.0 to about 8.0 grams per square meter. In yet another aspect, the blended starch coating may have a dry coat weight in a range of from about 3.0 to about 7.0 grams per square meter. In yet another aspect, the blended starch coating may have a dry coat weight in a range of from about 4.0 to about 6.0 grams per square meter.
The blended starch coating may be applied directly on the cellulosic substrate. The lipophobic starch having the shear-thinning rheology facilitates an ability of the blended starch coating to remain predominantly at the surface of the cellulosic substrate rather than penetrate too much into pores of the cellulosic substrate.
A method for manufacturing the coated cellulosic substrate may include delivering the blended starch composition to a metering size press and applying a coating of the blended starch composition from the metering size press onto a cellulosic substrate. The process of applying a starch composition to a cellulosic substrate by metering size press creates a challenge of runnability of the starch coating. The presence of the food grade starch in the blended starch coating of the present description provides the blended starch coating with sufficient runnability during the metering size press process while maintaining suitability for contact with food.
In an aspect, the blended starch composition is delivered to the metering size press has a solids content in a range of from about 17% to about 40%. In another aspect, the blended starch composition delivered to the metering size press has a solids content in a range of from about 20% to about 28%. In yet another aspect, the blended starch composition delivered to the metering size press has a solids content in a range of from about 22% to about 26%. In yet another aspect, the blended starch composition delivered to the metering size press has a solids content in a range of from about 23% to about 25%.
After the blended starch composition is applied, it may be dried such as via contact, forced air, and/or infrared (IR) drying.
The coated cellulosic substrate may be utilized as a coated linerboard of a corrugated structure.
FIG. 2 is a cross-sectional view of an exemplary corrugated structure comprising the coated cellulosic substrate according to an aspect of the present description.
The corrugated structure 1 has a coated cellulosic substrate 10 as described above, another linerboard 30 (e.g. standard linerboard) and a corrugated medium 20
For example, finished rolls of coated linerboard of the present description may be sent to corrugated box facilities. The coated linerboard may be single- or multi-wall corrugated to a standard medium along with a standard linerboard for an outer printed surface.
The corrugated structure may be utilized to form a corrugated package.
FIG. 3 depicts a cross-sectional view of an exemplary corrugated package that includes the coated cellulosic substrate according to an aspect of the present description.
The corrugated package 100 may include an inner surface 102 and an outer surface 104, wherein the coated cellulosic substrate having the blended starch coating forms the inner surface 102 to provide oil and grease resistance to the corrugated package 100. For example, boxes maybe dye cut and/or printed from the corrugated structure, and the blended starch coated linerboard becomes the inner surface of the package (e.g., pizza box) where it functions to mitigate the transfer of oil and grease through the corrugated board to the outer surfaces of the package.

EXAMPLES

Inventive Example

Ingredion Filmkote 370 as blended with Ingredion National 912 to produce a blended starch composition. The starches were blended in a 70/30 weight ratio of Ingredion Filmkote 370 to Ingredion National 912. The blended starch composition was cooked via continuous jet cooking, or batch cooking, at the paper mill and delivered to the film sizer at 23 percent to 25 percent, by weight, solids content. The blended starch chemistry allowed for film sizer (AKA Metering size press) application on uncoated linerboard with Gurley porosity in the 15 seconds per 100 cubic centimeters to 60 seconds per 100 cubic centimeters range, allowing for a dry coat weight in a range of 4.0 grams per square meter to 6.0 grams per square meter, while allowing a stable film to be formed and preventing metering rod deflection. After the blended starch composition was applied and dried via contact and/or infrared (IR) drying on the paper machine, the coated linerboard sheet was tested for oil and grease resistance (OGR) functionality, strength, and other properties.
This coated cellulosic substrate could be used in many applications requiring short duration grease resistance. Single service food applications (such as pizza box market applications) are a prime target market, but other markets would be available.

Comparative Example

Earlier trials revealed that unblended Ingredion Filmkote 370 presented runnability issues during film sizer (AKA Metering size press) application on uncoated linerboard with Gurley porosity in the 15 seconds per 100 cubic centimeters to 60 seconds per 100 cubic centimeters.
Although various examples of the disclosed coated cellulosic substrates and methods for manufacturing coated cellulosic substrates have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.

Claims

1. A method for manufacturing a coated cellulosic substrate, the method comprising:

delivering a blended starch composition to a metering size press, the blended starch composition comprising:

a lipophobic starch having a shear-thinning rheology, and

a food grade starch; and

applying a coating of the blended starch composition from the metering size press onto a cellulosic substrate.

2. The method of claim 1, wherein the cellulosic substrate has a basis weight in a range of from about 16 to about 36 pounds per 1000 square feet.

3. The method of claim 1, wherein the cellulosic substrate has a basis weight in a range of from about 21 to about 31 pounds per 1000 square feet.

4. The method of claim 1, wherein the cellulosic substrate has a basis weight in a range of from about 24 to about 28 pounds per 1000 square feet.

5. (canceled)

6. The method of claim 1, wherein the cellulosic substrate has a Gurley porosity in a range of from about 5 seconds per 100 cubic centimeters to about 200 seconds per 100 cubic centimeters.

7. The method of claim 1, wherein the cellulosic substrate has a Gurley porosity in a range of from about 10 seconds per 100 cubic centimeters to about 150 seconds per 100 cubic centimeters.

8. (canceled)

9. The method of claim 1, wherein a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 1:99 to about 99:1.

10. The method of claim 1, wherein a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 30:70 to about 98:2.

11. The method of claim 1, wherein a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 40:60 to about 95:5.

12-14. (canceled)

15. The method of claim 1, wherein the food grade starch has a water fluidity in a range of from about 1 to about 80.

16. The method of claim 1, wherein the food grade starch has a water fluidity in a range of from about 5 to about 70.

17. The method of claim 1, wherein the food grade starch has a water fluidity in a range of from about 10 to about 60.

18-19. (canceled)

20. The method of claim 1, wherein the blended starch composition has a solids content in a range of from about 17% to about 40%.

21. The method of claim 1, wherein the blended starch composition has a solids content in a range of from about 20% to about 28%.

22. The method of claim 1, wherein the blended starch composition has a solids content in a range of from about 22% to about 26%.

23. (canceled)

24. The method of claim 1, wherein the coating has a dry coat weight in a range of from about 1.0 g/m²to about 10.0 g/m².

25. The method of claim 1, wherein the coating has a dry coat weight in a range of from about 2.0 g/m²to about 8.0 g/m².

26-27. (canceled)

28. The method of claim 1, wherein the shear-thinning rheology of the lipophobic starch allows the blended starch coating to become thinner as the blended starch coating is driven under high shear into a nip of the metering size press but then regain viscosity as blended starch coating flows away from the nip, which serves to reduce starch penetration into the cellulosic substrate to ensure that the lipophobic starch predominantly remains at the surface of the cellulosic substrate to ensure sufficient oil and grease resistance.

29. A method for manufacturing a coated cellulosic substrate, the method comprising:

a lipophobic starch having a shear-thinning rheology, and

a food grade starch having a water fluidity in a range of from about 1 to about 80,

wherein a weight ratio of the lipophobic starch to the food grade starch is in a range of from about 1:99 to about 99:1, and

wherein the blended starch composition has a solids content in a range of from about 17% to about 40%; and

applying a coating of the blended starch composition from the metering size press onto a cellulosic substrate to achieve a dry coat weight in a range of from about 1.0 g/m²to about 9.0 g/m², wherein the cellulosic substrate has a basis weight in a range of from about 16 to about 69 pounds per 1000 square feet and a Gurley porosity in a range of from about 5 seconds per 100 cubic centimeters to about 200 seconds per 100 cubic centimeters.

30. A coated cellulosic substrate, comprising:

a cellulosic substrate; and

a blended starch coating on the cellulosic substrate, the blended starch coating comprising a lipophobic starch and a food grade starch.

31-54. (canceled)