Methods for improving functional properties of pulp and pulp-based materials

Abstract

Described are methods for treating a lignocellulosic fibrous material substrate with an additive formulation, wherein the method includes providing the substrate to be treated; partially drying the substrate; applying the additive formulation to the substrate before the substrate has completely dried, thereby forming a treated substrate; and subjecting the treated substrate to a reduced pressure environment before the treated substrate has completely dried, wherein the reduced pressure environment impels the additive formulation into the treated substrate at a preselected concentration or along a preselected concentration gradient. The methods can include an optional step of completely drying the treated substrate following the step of subjecting the treated substrate to the reduced pressure environment. Also described are methods of manufacturing a three-dimensional formed article or a flat two-dimensioned article from such treated lignocellulosic fibrous material substrates.

Description

METHODS FOR IMPROVING FUNCTIONAL PROPERTIES OF PULP AND PULPBASED MATERIALSRELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application 63 / 552,276 filed February 12, 2024. The entire contents of the above application are incorporated by reference herein.FIELD OF THE INVENTION

[0002] This application relates to methods for improving functional properties of pulp materials and pulp-based materials.BACKGROUND

[0003] Paper-making processes commonly employ additives or add-on substances to improve the functional properties of pulp, such as to improve the oil, grease, or water resistance (OGWR) of paper-based products. Additives typically are applied in the wet end of the paper-making process, or are applied to the surface of the material when it is dried. Difficulties in applying these additives can impair the performance of the finished article of manufacture. The use of sizing agents for OGWR exemplifies the difficulties that accompany conventional methods for improving the functional properties of pulp-derived materials.

[0004] Those functional properties intended to improve resistance to oil and grease permeability and / or that improve resistance to water vapor permeability, and / or that improve resistance to other fluids (liquids or gases) are termed “barrier treatments,” or “barrierproducing” materials. The resistance to selected fluids that they impart to the formed substance or substrate matrix, such as oil and grease resistance (OGR) and / or water or watervapor resistance (WVR) properties, are termed “barrier properties.” Sizing agents are commonly used as wet-end additives in the paper making process or applied as a coating to dried paper to impart barrier properties to pulp-derived articles, making them resistant to fluid penetration.

[0005] Sizing agents added directly to the pulp in the wet end of the papermaking process become integrated with the paper fibers and provide resistance to liquid penetration throughout the paper sheet. Sizing agents used in this manner are also termed internal sizingagents. Examples of such wet-end-additives used as internal sizing agents include alkyl ketene dimer (AKD) and alkyl succinic anhydride (ASA).

[0006] Other sizing agents, termed surface sizing agents, can be applied as coatings to the surface of the dried paper product to create a protective layer on the surface that reduces absorption of liquids. Common surface agents include polyvinyl alcohol (PVA), styrenebutadiene latex, and starch. As is known in the art, surface sizing agents can be applied by a number of methods such as being rolled-on, wiped-on, sprayed-on, curtain coated-on, poured-on, and bladed-on, among others. However, both internal and surface sizing agents have limitations in providing barrier properties to paper products.

[0007] Internal sizing agents can enhance the hydrophobic properties of hydrophilic pulp; however, the produced sheet remains porous and tends to have less than ideal performance. Achieving uniform distribution of the wet-end additives is an additional challenge, and requires rigorous mixing. It is also difficult to attain retention of the wet-end additives in the pulp mixture when they are mixed together, and it is typically necessary to include additives that act as retention aids to help the sizing additives link to the pulp’s cellulose fibers.

[0008] Surface sizing agents impart barrier properties by decreasing the porosity of the surface layer. However, once the barrier on the surface is breached, fluid can quickly penetrate into the interior of the paper product, since the surface sizing agent only modifies the hydrophilic nature of the product’s top layer and leaves the layers beneath vulnerable to fluid incursion. Furthermore, surface sizing agents distributed as aerosols, such as spray-on coatings, typically require delicate process optimization without which the coating may not adhere well to the underlying paper substrate. Another drawback with surface sizing is that it needs to be applied post-production to the dried material, so that a second drying step is required after the surface sizing is applied.

[0009] A combination of wet-end additives and a post-processing coating helps improve the overall OGWR performance of the substrate and mitigates the performance drawbacks of each method. However, applying two different types of barrier treatments complicates processing logistics and adds production costs. There remains a need in the art, therefore, for a simple and economical way of optimizing performance of additives that produce advantageous properties such as barrier properties in pulp-derived articlesSUMMARY

[0010] Disclosed herein, in embodiments, are methods for treating a substrate comprising a lignocellulosic fibrous material with an additive formulation, the method comprising: providing the substrate to be treated; partially drying the substrate drying the substrate; applying the additive formulation to the substrate before the substrate has completely dried, thereby forming a treated substrate; and subjecting the treated substrate to a reduced pressure environment before the treated substrate has completely dried, wherein the reduced pressure environment impels the additive formulation into the treated substrate at a preselected concentration or along a preselected concentration gradient. In embodiments, the method can optionally include the steps of providing the lignocellulosic fibrous material and processing the lignocellulosic fibrous material to produce the substrate. In embodiments, the substrate is a pulp-derived substrate, and the pulp-derived substrate can be a pulp-derived nanocellulosic substrate. In embodiments, the lignocellulosic fibrous material is a plant-based waste material, which can be an agricultural waste material or a forestry waste material. In embodiments, the lignocellulosic fibrous material is a material from a special-purpose crop. In embodiments, the lignocellulosic fibrous material is a whole plant material. In embodiments, the additive formulation comprises an additive selected from the group consisting of a barrier-producing additive, a mechanical-modifying additive, an appearancemodifying additive, and a specialized additive. In embodiments, the additive is the barrierproducing additive, and the barrier-producing additive produces at least one of oil and grease resistance and water resistance; in embodiments, the barrier-producing additive comprises methylcellulose and rosin, and can further comprise nanocellulose elements. In embodiments, the step of processing comprises a substep of pulping the lignocellulosic fibrous material. In embodiments, the step of applying takes place before commencing the step of partially drying. In embodiments, the step of applying comprises mixing the additive formulation into the substrate; in other embodiments, the step of applying comprises applying the additive formulation to a surface of the substrate, which can comprise a spray-on processing method. In embodiments, the step of subjecting can be commenced before the treated substrate has begun the drying process, or the step of partially drying can take place following the commencement of the step of subjecting. In embodiments, the method further comprises modifying the reduced pressure application during the step of subjecting, to modify the preselected concentration or a preselected concentration gradient at one or more preselected time intervals.

[0011] In embodiments, the methods described above further comprise the step of completely drying the treated substate following the step of subjecting. Such methods can further comprise applying a second additive formulation to the treated substrate following the step of subjecting the treated substrate to the reduced pressure environment and before the step of completely drying, thereby producing a twice-treated substrate. In embodiments, the second additive formulation can comprise a second additive that differs from the additive in the additive formulation applied to the substrate. In embodiments, the additive formulation can be mixed into the substrate to form the treated substrate, and the second additive formulation can be applied to the surface of the treated substrate. In embodiments, the methods further comprise a step of subjecting the twice-treated substrate to a second reduced pressure environment before the step of completely drying, wherein the second reduced pressure environment impels the second additive formulation to penetrate the twice-treated substance at a second preselected concentration or along a second preselected concentration gradient.

[0012] In embodiments, the step of applying the second additive formulation takes place by exposing the treated substrate to an applicator that bears or contains the second additive formulation, wherein the applicator applies the second additive formulation to a surface of the treated substrate to produce a treated surface. In embodiments, the applicator comprises an internal reservoir. In embodiments, the applicator applies the second additive formulation by contacting the treated substrate, thereby producing the treated surface. In embodiments, the applicator dispenses the second additive formulation while remaining at a designated distance from the treated substrate, thereby producing the treated surface; the designated distance can vary over time, with a consequent variation in amount of second additive formulation dispensed onto the treated surface over time. In embodiments, the applicator is pre-formed to conform to an external shape of the treated substance. In other embodiments, the applicator is flexible and conforms to the external shape of the treated substrate after contacting it; such an applicator can be formed from an article selected from the group consisting of a sheet, an absorbent meshwork, a foam, and a sponge. In embodiments, the applicator comprises a non-absorbent sheet placed in close proximity to the treated substrate, wherein the second additive formulation is directed into and through a space between the non-absorbent sheet and the treated substrate. In embodiments, the applicator applies the second additive formulation to the surface of the treated substrate by directing the second additive formulation to pass from an external, non-delivery surface of the applicator into and through the applicator, wherein the applicator is in an effective proximity to thetreated substrate; the effective proximity can comprise a contact between the applicator and the treated substrate, and the contact can be a partial contact.

[0013] Further disclosed herein, in embodiments, are methods of producing a three- dimensional formed article, comprising producing the twice-treated substrate by the methods described above and molding the twice-treated substrate to produce the three-dimensional formed article. Also disclosed herein, in embodiments, are methods of producing a flat two- dimensional article, comprising producing the twice-treated substrate by the methods described above, wherein the additive formulation is applied to the substrate in a wet end of substrate processing, and shaping the twice-treated substrate to form the flat two-dimensional article following the step of subjecting the twice-treated substrate to the reduced pressure environment.DETAILED DESCRIPTION a. Wet-on-wet processing generally

[0014] Disclosed herein, in embodiments, is a one-step method for applying an additive formulation to a lignocellulosic fibrous material to impart desirable functional properties thereto. Lignocellulosic materials are formed of polysaccharides (cellulose and hemicellulose) bound with varying amounts of lignin. Lignocellulosic materials can include virgin biomass, as is found naturally occurring plants like trees, bushes, and grass. Lignocellulosic materials can include waste materials from consumption or from industries such as agriculture (e.g., com stover and corncobs, sugarcane bagasse, straw, oil palm empty fruit bunch, pineapple leaf, apple stem, coir fiber, mulberry bark, rice hulls, bean hulls, soybean hulls (or “soyhulls”), cotton linters, blue agave waste, North African glass, banana pseudo stem residue, groundnut shells, pistachio nut shells, grape pomace, shea nut shell, passion fruit peels, fique fiber waste, sago seed shells, kelp waste, juncus plant stems, and the like), or forestry (saw mill and paper mill discards). Lignocellulosic materials can include specialty -purpose crops such as switchgrass and elephant grass cultivated for uses such as biofuels, capable of multiple harvests. Plants having use as lignocellulosic materials can be woody (such as trees, with firm stems, and with multiyear growth cycles) or non-woody, having weak stems and annual or limited multiyear growth cycles. Non-woody plants are particularly advantageous, typically possessing large amounts of lignin relative to the amount of cellulose they contain. Lignocellulosic materials in general, including those made from whole plant materials such as bagasse and switchgrass, can be used as substrates for the methods disclosed herein. While such “whole plant” lignocellulosic materials are typicallynot sufficiently strong to be manufactured into sheets and formed articles, these materials can be reinforced with other substances to improve their strength and thus render them suitable for the methods disclosed herein.

[0015] Advantageously, the methods disclosed herein can be used with substrates that are obtained by processing lignocellulosic materials to obtain pulp. As would be understood by those of skill in the art, different techniques are available for processing the various lignocellulosic materials to produce pulp. In preferred embodiments, the methods disclosed herein can be applied to pulp-derived cellulosic or nanocellulosic articles of manufacture to produce functional properties such as barrier properties in the products made during papermaking or comparable processes. As used herein, the term “pulp-derived” refers to a substrate or an article of manufacture that comprises a pulp matrix or pulp-based matrix. As used herein, the term “pulp” refers to a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from organic feedstock such as wood, fiber crops, agricultural waste, waste paper, or rags; “pulp-based” refers to those materials that have been derived from pulp by processing, forming, or treating the pulp while still retaining some pulp or pulp derivatives within their substance.

[0016] Nanocellulosic fibers are a subspecies of pulp-based materials. As used herein, the term “nanocellulosic” refers both to nanofibrillated cellulose and microfibrillated cellulose (which are both collectively embraced by the term “nanocellulose elements” (NCEs)). Cellulose nanofibers and cellulose microfibers can be distinguished from each other based on their size and shape: cellulose nanofibers (CNF, also known as “nanofibrillated cellulose” or “NFCs”) are much smaller in diameter than cellulose microfibers (CMF, also known as “microfibrillated cellulose” or “MFCs”). CNF can be straight and rod-like, while CMF are larger in diameter, more flexible in appearance and can be irregular in shape. While the literature cites a range of dimensions for CNF and for CMF, CNF fibers are nanoscale in dimension (for example, having a diameter between 4-20 nm), while CMF can be much larger. However, CMF fibers typically still have diameters in the nano-range, for example 20- 100 nm or larger.

[0017] The methods of applying barrier-producing additives or other additive formulations to pulp-derived or other cellulosic or nanocellulosic substrates as disclosed herein can be termed the “wet-on-wet” or WOW method. The methods disclosed herein offer an intermediate form of application for additive formulations, offering advantages that are provided by the internal integration of such formulations (as seen for example with internalsizing agents) and that are provided by the external application of such formulations (as seen for example with for surface sizing agents). b. Wet-on-wet processing for pulp and pulp-based substrates

[0018] The WOW method as disclosed herein is suitable for use with pulp-derived substrates, and can be employed in conjunction with the conventional technologies used for papermaking and other processes involving such substrates. The WOW method is applicable to the full range of production processes for pulp-derived products, including without limitation products that are formed by contouring, molding, or otherwise shaping the substrate, and products that roll or otherwise flatten the substrate into sheets, as described below. When used to produce pulp-derived products, the WOW process conserves additive materials, delivers exceptional performance from the additives employed, and, in embodiments, uses a single drying step to produce a fully functional finished product, providing advantages overall when compared to standard mix-in techniques for achieving oil and grease resistance. Because the WOW process allows the functional additive to infiltrate the substrate effectively, and because the functional additive permeates the substrate after its water content has been reduced, there is less need for adding retention aids, which streamlines the overall process, reduces cost, and improves performance by mitigating processing problems such as undesirable foaming. The WOW method also avoids the issues with coating adhesion that affect externally applied sizing agents and other coating formulations, because the additive is integrated into the substrate. Thus, WOW can eliminate the warpage due to the differential shrinkage of the coating vs the substrate when the coating formulation’s solvent evaporates.

[0019] Managing viscosity is an important factor in the WOW process. Low viscosity is preferred for both ease of spraying, but also to allow the additive formulation to diffuse through the pulp matrix. Higher viscosity will result in slower diffusion through the pulp matrix and a more defined concentration gradient. In embodiments, it has been determined that the viscosity of the additive formulation impact the spray / addition time as well as the absorption time and diffusion into the pulp matrix. As viscosity increases, less of the overall formulation needs to be applied to the target surface to achieve the desired effect, resulting in faster spray; lower viscosity requires more of the formulation to be applied, resulting in longer times required for spraying and slower absorption. One way to modify the viscosity is to vary the dilution of a particular barrier-producing additive.

[0020] Modifications of the WOW process can be implemented to obtain specific functional outcomes. For example, the vacuum process used to effect the migration of thefunctional additive into and through the substrate can be programmed to vary over time according to preselected timelines, a process referred to herein as “vacuum ramping.” For example, the negative pressure provided by the vacuum apparatus can gradually increase over time, to improve the penetrance of the additive into the substrate even as the substrate dries or otherwise becomes more resistant to the additive’s incursion. Or, for example, the amount of negative pressure can be decreased over time (i.e., with less of a vacuum becoming applied over time) so that the additive is pulled into the substrate more strongly initially, and then less strongly over time. The amount of vacuum can be varied over time, ranging from stronger to less strong, and then increasing in a predetermined pattern, which will result in a gradient of additive being laid down within the substrate. With multiple variations of the vacuum, a sequence of gradients can be established within the substrate, which can be suitable for specialized applications. Advantageously, the application and variation of negative pressure can be programmed and controlled electronically, via computer-based applications and / or mobile apps. Such controllers can further be connected to sensors that measure or indicate the conditions of the substrate itself or of the system for modifying the substrate, so that the application and variation of negative pressure can be self-modulating in response to processing conditions.

[0021] Multiple additives can be intromitted into the substrate, and can be positioned at various levels within the substrate by applying a customized pattern of vacuum variability for each one, a process referred to herein as “split WOW.” For example, one additive can be introduced via a variable vacuum pattern to have its greatest concentration more centrally within the substrate, while a second additive can be introduced by a second variable vacuum pattern to have its greatest concentration more peripherally. This process allows two different functionalities to be produced in the substrate, with each one localized in a different region. This can be especially advantageous when the two functionalities are both related to a single property, such as a barrier property. In this situation, two different aspects of the property, such as oil / grease resistance and water resistance as barrier properties, can be imparted using the WOW method, one as a mix-in and one as a wet-on-wet coating. In an exemplary embodiment, using a rosin emulsion and a methylcellulose / NCE / chitosan solution, the rosin emulsion can be mixed into a suitable substrate, such as a pulp or pulp-based matrix, to become integrated with the substrate via the application of a WOW vacuum gradient or gradient pattern; subsequently, the methylcellulose / NCE / chitosan solution can be sprayed on the treated substrate at the end of the processing, with further WOW exposure as needed. In this way, dual or amplified functionality can be obtained. In this example, with the rosinemulsion embedded in the interior and the methylcellulose / NCE / chitosan solution forming a “skin” that is more exterior, the two additive formulations each impart OGWR properties, amplifying the effect that could be attained with either one by itself.

[0022] The WOW method is compatible with a wide range of conventional fabrication processes, as described below. In more detail, the WOW method can be integrated with conventional mix-in and spray-on processing methods, using existing equipment. As an example, the additive can be sprayed on to a surface using spray nozzles that are part of the existing apparatus, for example those nozzles that are used conventionally to clean the mold in between its uses. Other pieces of equipment can be employed or repurposed to achieve the objectives of the WOW method. The fabrication process can also be adapted to be integrated with the WOW method.

[0023] For contoured substrates (e.g., containers formed from molded fibrous substrates such as pulp) that use a wet press method for shaping the formed article of manufacture, a barrier-producing formulation or any additive formulation can be deposited in accordance with the WOW method on the targeted side of the substrate by spray or by a secondary dip before the entire article is dried, or by using suction after the substrate is semidry. For example, the formulation can be applied in the wet-press processing of a molded pulp fiber container after the basic substrate is formed into the molded article via vacuum through a porous supportive structure such as a mesh mold but before the molded material enters the thermoformer. If a pre-press step is included in the production line, applying the barrier-producing or other advantageous formulation prior to the pre-press stage can help the additives enter the matrix efficiently.

[0024] The WOW method can also be used in the dry-press process for forming molded fiber products, which consists of vacuum forming the fibrous substrate, air drying it, and finally hot-pressing. In these situations, the barrier-producing or other advantageous formulation can be applied after the fibrous (e.g., pulp-derived) substrate is formed via vacuum through a porous supportive structure such as a mesh mold and before the substrate enters the dryer. The formulation is thus deposited on the targeted side of the article before it is fully dried, so that the formulation can penetrate the surface and enter the substance of the article, thus forming a surface barrier but also infiltrating the article itself to add water resistance and / or oil and grease resistance from within.

[0025] For producing flat rolls of paper, a barrier formulation or other advantageous additive formulation having functional properties can be deposited on the targeted side of the substrate by spray, roll-on, wipe-on or other deposition methods after the wet web leaves thepressing section but before the drying process takes place, for example when the pulp mats providing the substate for the paper rolls contain 50-60% water. The integration of WOW in paper production requires minimal modification of the standard equipment: a spray bar can be installed in one or more strategic locations over the moving wire of the paper machine to dispense the additive on the partially dried pulp mat. A secondary spray can also be positioned to target both sides of the pulp mat. The position and height of the spray system can be altered to produce the desired concentration gradient in the final paper product.

[0026] When applying wet-end barrier-producing or other functional additives onto a partially dried pulp substrate via the WOW method, the additives initially form a layer on the top of the substrate then diffuse through the porous wet pulp substrate to create a concentration gradient in the thickness direction. Applying a low vacuum can help the movement of additives into and through the pulp substrate; however, using a vacuum to expedite the WOW process requires close monitoring so that the additives are not removed from the substrate by the vacuum itself. Applying such closely-monitored pressure after WOW introduction of the barrier or other additive formulation into the substrate closes the pores in the substrate after the additives have entered the bulk of the matrix, helping to enclose the additives tightly within the matrix to enhance their effectiveness. In general, WOW processing itself helps reduce porosity in the system while adding a strong concentration of material towards the more external region of the molded fiber material; applying pressure during the manufacturing process adds to the effectiveness of the additive being introduced into the substrate via the WOW process. In embodiments, WOW processing can be used in combination with the mix-in method of adding internal sizing agents or in combination with traditional methods of adding surface sizing agents, although this adds extra steps and extra cost to the procedures.

[0027] In an embodiment, the WOW method can be employed as part of a “doubledip” application process. In such a process, the porous supportive structure, e.g., a meshed bowl template, having a vacuum assembly attached for the WOW method is first dipped into a container of pulp. The pulp forms on the surface of the porous supportive structure, e.g. mesh, and becomes semi-dry via the application of heat and vacuum. Then the porous supportive structure with the in situ formed pulp (which has a consistency like felt), is dipped into an additive formulation in a second container, for example a formulation having OGWR properties. With the vacuum still running, the additive formulation from the second container (termed “the second formulation” herein) is applied to the external surface or surfaces of the bowl structure, with the consistency of the bowl substrate tending to keep the formulation onthe surface(s) as a separate layer. The applied suction, however, pulls the second formulation into the substrate according to a gradient that depends on the amount of suction and its timing, as described above. The portion of the formed object that encounters the second formulation during this process can be termed the “treated substrate.” While the procedure described above has been termed a “double-dip” application process, it is understood that multiple “dips” can be employed to expose the formed substrate to multiple formulations. Each of these formulations can then be distributed within the substrate matrix by application of suction following the distribution of the formulation on the substrate surface. Thus multiple “dips” can be achieved to treat the substrate with various additives or formulations at varying concentrations.

[0028] As an alternative to migrating the formed substrate from one container to another, the second “dip” with application of the additive formulation can be replaced by exposing the already -treated substrate of the formed object to an applicator that bears the additive formulation. In one practice of this method, the porous supportive structure, such as a meshed bowl template, having a vacuum assembly attached for the WOW method is first dipped into a container of pulp as described above, so that the pulp forms on the surface of the porous supportive structure and becomes semi-dry via the application of (alone or in combination) a vacuum, heat, forced air, or any other method to induce drying. In this way, the pulp is efficiently formed into the desired shape for an article of manufacture, such as a plate, cup, bowl, or other shape, as described herein. In this alternative method for applying an additive formulation to a surface of the pulp-based article of manufacture, the porous supportive structure (e.g., the mesh) and the semidry pulp layer it supports is then transferred to come into contact with an applicator bearing the desired additive formulation.

[0029] As used herein, the term “applicator” refers to any structure, sheet, or pad that is dimensionally adapted for applying the additive formulation to the surface of the pulp by contacting said surface or by remaining at a preselected distance but coming into sufficient proximity to said surface so as to permit the additive formulation to be conveyed onto said surface (e.g., by spraying, pouring, spreading, sprinkling, drizzling, or otherwise dispensing and / or dispersing the additive formulation onto the surface at a designated distance from it). This designated distance can remain the same during the application process, or can be varied to achieve different amounts of additive formulation amounts at different times. The surface of the formed article that is treated with the additive formulation can be referred to as the “treated surface,” and the surface of the formed article designated for treatment can be referred to as the “designated treated surface.” The additive formulation applied by theapplicator can remain substantially on the treated surface or it can penetrate the treated surface to reach preselected depths, to become embedded therein at preselected concentrations or concentration gradients.

[0030] The distance between the applicator and the designated treated surface that is sufficient for treating the designated treated surface with the additive formulation can be termed an “effective distance” between the applicator and the designated treated surface, and the applicator and the designated treated surface are in “effective proximity” to each other. In some embodiments, the effective proximity for obtaining the desired treatment of the substrate with the additive formulation requires partial or full contact between the applicator and the designated treated surface. In other embodiments, the effective proximity does not require any contact between the applicator and the substrate; instead the additive formulation can be applied through an applicator at a designated effective distance from the designated treated surface.

[0031] In embodiments, the applicator is pre-shaped so that it conforms to the shape that has been formed from the pulp, such as a plate, cup, bowl, or other shapes as required by the desired end use. For example, a clamshell or a boxy shape could be formed from the pulp, or a customized shape for a specialized usage, such as a shape to conform to the shape of a bottle for transporting wine or other liquids. However, the systems and methods here are shape-agnostic: regardless of the shape, a pre-formed applicator can be provided that conforms to the shape and directs the formulation to contact the semi-dry article of manufacture.

[0032] In an exemplary embodiment, the semi- dry article of manufacture supported internally by the porous supportive structure (e.g., the mesh template) can be directed to contact and closely interdigitate with the pre-formed applicator so that the additive formulation is conveyed onto the designated treated surface of the article, such as the outer surface of the plate, cup, bowl, clamshell, or other preselected shape for the article of manufacture. In embodiments, the applicator can be flexible, for example formed as an article such as a sheet, an absorbent meshwork, foam, or sponge, or the like, so that it is able to conform to the shape of the formed article when it comes into contact with the designated treated surface, thus allowing the transfer of the additive formulation from the applicator to the designated treated surface of the formed article. For example, a flexible applicator in the form of a sheet, an absorbent meshwork a foam, a sponge, or the like can be draped over the designated treated surface to optimize contact between the applicator and the surface, or a designated treated surface can be pressed into contact with an absorbent pad applicator or asponge applicator to optimize their contact. In certain embodiments, the applicator whether pre-formed or flexible, can comprise a non-absorbent sheet placed in close proximity to the treated surface, with the additive formulation being directed into and through the space between the non-absorbent sheet and the formed article’s surface; for example, the fluid can be directed into this space by capillary action, or it can be forced under pressure to enter the space. In yet other embodiments, the applicator comprises delivery mechanisms such as one or more spray nozzles that are calibrated to deliver an appropriate dose of the additive formulation to the designated treated surface. In specific embodiments, the applicator’s shape can be designed to treat the entire designated treated surface or just a certain section thereof, depending on the design requirements of the particular article of manufacture.

[0033] In any embodiment of the applicator (e.g., pre-formed or flexible, contacting or distanced), the additive formulation can be applied to a non-delivery surface of the applicator and can then percolate, diffuse, or otherwise pass through the applicator substance to contact or otherwise be deployed upon the surface of the formed article that is designated for treatment. In certain embodiments, the applicator (whether pre-formed or flexible, contacting or distanced), can contain an internal reservoir for storing the additive formulation with delivery channels that allow the delivery of the additive formulation to the applicator surface that is responsible for delivering the additive formulation to the designated treated surface. Delivery channels for delivering the additive formulation into the applicator can be microscopic or macroscopic, and they can be engineered to be consistent with fluid delivery by any appropriate means, whether by capillary action, by applied pressure differences, by hydrostatic or osmotic pressures, or otherwise.

[0034] Each arrangement has advantages for manufacturing: a preformed applicator can be more suitable for use with a smooth and regular designated treated surface, such as a formed bowl, cup, container, sheet, or other regularly formed object, while a flexible applicator can be more suitable for use with designated treated surfaces that are more irregular, or that have variance in shape from one formed article to the next. Modifications of the foregoing can be envisioned by skilled artisans using no more than routine experimentation, and are understood to fall within the scope of the inventions disclosed herein. c. Exemplary additive formulations

[0035] Additives used to provide desirable properties as described herein, such as barrier properties, mechanical properties, and other specialized properties, can be formulated for convenient use in the WOW method. For example, such additives can be, withoutlimitation, barrier-producing additives, mechanical-modifying additives, appearancemodifying additives, or other specialized additives. Non-limiting examples of such formulations that can be used to provide barrier properties are set forth below.

[0036] Formulations imparting OGWR properties can provide all the functional features of oil, grease, and water resistance, or can provide a limited subset of functional features such as oil and grease resistance, depending on the substrate being treated and the functional goals to be achieved.

[0037] A formulation with full OGWR properties for use with the WOW method can be produced as described below. Such a formulation is suitable for use with a pulp-containing substrate such as, but not limited to, wood pulps derived from coniferous and deciduous trees and non-wood-pulps that can be derived from other plant sources such as straws (e.g., wheat, rye, rice, and the like), grasses (e.g., miscanthus and the like), canes (e.g., bagasse and the like), plant bark (e.g., mitsumata, paper mulberry and the like), woody stalks (e.g., bamboo, flax, help, and the like), seed, leaf, or bast fibers (e.g., cotton, abaca, sisal, and the like) or that can be derived from fibrous material derived from other pulp-containing products (e.g., recycled paper products, recycled cardboard, recycled rags, and the like.

[0038] Formulations with oil and grease resistant properties for use with the WOW method can be produced according to several different processes. Such formulations are suitable for use with substrates having water resistance already added to the substrate by a mix-in technique; in such situations, the mix-in additives provide no oil and grease resistance (just water resistance), so that a secondary coating is required. Using the WOW method, the selected OGR formulation can be coated / sprayed onto the outer surface of the substrate, with the application of a vacuum or a vacuum ramp used to create a gradient within the substrate. Such a process yields a substrate having both water resistant and OGR properties.

[0039] In other embodiments, a formulation having full OGWR properties for use with the WOW method can be prepared. Such a formulation comprises rosin, methylcellulose (MC), and a reinforcing amount of a NCE such as NFCs. In this formulation, an amount of rosin can be solubilized in ethanol to provide a 1 : 10 rosimethanol solution by weight, and an amount of MC can be solubilized in water to provide a 1 :20 MC: water solution by weight. An amount of NFCs equal to about one-third the amount of MC by weight can then be added to the MC solution. The two mixtures (the rosin-containing one and the MC / NCE-containing one) can then be mixed together to provide an OGWR formulation for use with the WOW method. A formulation with OGR properties for use with the WOW method can be prepared that comprises 4000 cP MC, high molecular-weight chitosan, and a reinforcing amount of aNCE such as NFCs in an aqueous solution. To prepare such a formulation, the MC is solubilized in water, followed by addition of NFCs, followed by the addition of A1C13 to lower the pH of the solution to a pH between about 5 and about 6; after that, the chitosan is added. The chitosan had previously been prepared as a 1% solution by adding the requisite amount of chitosan powder to a 0.05M HC1. The resulting formulation has these ingredients in the following exemplary ratios: 3: 1 : 1 (MC:NFC: chitosan). The amount of water can be varied, depending on the methods of application that are employed. For example, an amount of water to produce a 3 : 1 : 1 :795 (MC:NFC:chitosan:water) solution provides a viscosity that is suitable for spray or double dip methods as disclosed herein. An OGR formulation such as is described above can be applied to the pulp mixture or to a formed article by spray-on, double-dipping, transfer coating, and the like. The aqueous formulation described above is viscous, but the viscosity can be modified by increasing (or decreasing) the amount of dilution.

[0040] In one OGR formulation, methylcellulose and a NCE such as NFC can be used, with the MC solubilized in water as described above and the NFCs then being mixed in. The final amount of water in the mixture can be adjusted to yield the desired viscosity for the formulation. Depending on its viscosity, the resulting mixture can be sprayed on the surface of the substrate or can be painted on or otherwise applied directly. Depending on the viscosity, the WOW method’s vacuum techniques can be applied to distribute the OGR formulation within the substrate and to remove any excess water. In embodiments, other additives can be included in the aqueous MC+NFC formulation. For example, an acidified solution of high molecular weight chitosan can be added to a MC+NFC formulation prepared as described above to enhance film- forming properties and oil / grease resistance. To create the necessary acid environment, A1C13 can be used to decrease the pH in the MC+NFC solution to a pH of between about 5 and about 6, and HC1 can be used to decrease the pH of the chitosan solution comparably. In embodiments, alternative formulations can be prepared using other cellulosics. For example, HPC can be used instead of MC. Other cellulosics can be used, for example, methylcellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose salt, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose acetate propionate, ethylcellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, hydroxypropyl methylcellulose phthalate, hydroxypropyl methylcellulose acetate, and the like. In exemplary embodiments, sodium carboxymethyl cellulose (NaCMC) can be used to provide OGR properties for the formulation. To use thissubstance to produce a coating formulation, NaCMC can be solubilized in water and then mixed with varying ratios of NFCs, producing formulations with NaCMC :NFC ratios that range from about 0.1 : 1 (NaCMC:NCF) to 1 : 1 (NaCMGNFC). In exemplary embodiments, cellulose acetate (CA) can be used as the cellulosic component of the formulation using acetone as a formulation, to produce a 2% CA solution (the “CA Solution”). This can be diluted by adding water to form a 2: 1 water: C A solution for the formulation. Other such formulations having OGR properties and suitable for use with the WOW method can be envisioned by artisans of ordinary skill using the principles disclosed herein and using no more than routine experimentation. In other exemplary embodiments, CA / rosin composites can be formed, using techniques such as anti-solvent precipitation; in embodiments, such composites can be used in double dip and transfer coating WOW methods.

[0041] OGR formulations, prepared as described above, can be used in the WOW method in combination with the WR formulation to produce both OGR and WR properties. For example, a formulation with WR properties for use with the WOW method can be prepared as a rosin emulsion to be mixed with the pulp slurry, by combining rosin (11.5%), PEG 1500 (1.15%), and MC (0.115%), with the percents for the ingredients being measured against the quantity of pulp in the slurry. In embodiments, the two mixtures (the rosincontaining one and the MC / NCE-containing one) can be mixed together, or both used separately or used sequentially to impart both OGR properties and WR properties to substrates being treated with the WOW method. Other such formulations having some or all OGWR properties and suitable for use with the WOW method can be envisioned by artisans of ordinary skill using the principles disclosed herein and using no more than routine experimentation. d. Applications and uses

[0042] Although described above in detail for use with barrier formulations, the WOW process can be used to deliver a wide variety of additive formulations onto fibrous substrates such as pulp-derived substrates. The recipient, semi-dry pulp matrix acts as a filter medium to prevent deep penetration of the applied formulation, and allows formulation gradients to be customized within the matrix for different purposes. In embodiments, other wet-end additives can be delivered together or independently of the formulation applied via the WOW process, with these wet-end additives being delivered either through a singular spray system with combined formulations or through multiple individual formulation spray systems arranged in succession. As mentioned above, a wide variety of additive formulationshaving functional properties can be deposited in pulp-derived substrates using the WOW method. Additional exemplary formulations are described below.

[0043] In embodiments, the WOW process can be used to deposit additive formulations that improve material performance of the recipient pulp-derived substrate. Articles of manufacture used in industries such as construction, automotive, sporting goods (e.g., eco-leather), and media-based filtration (e.g., liquid-solid separation) can benefit from improved mechanical properties that can be produced by delivering appropriate additives using the WOW method. For example, using the WOW process, a pulp-derived paper product can be created by infusing the pulp or pulp-based substrate with monomers, oligomers, or polymers that have specific mechanical properties, such as improved strength, flexibility, tear resistance, and the like. For example, the integration of a crosslinked elastic polymer solution into such a substrate using the WOW method can increase elasticity of the product upon drying.

[0044] In embodiments, appearance modifiers can be deployed via the WOW process individually or in combination with other additives. Examples include optical brighteners (stilbenes), pigments (kaolin clay, calcium carbonate, titanium dioxide, plastic pigment), pearlescence (mica, iron oxides), colorants (lakes, direct dyes, acid dyes) and more. Integration of a more complex spray system (e.g., inkjet) with software for electronic control allows for the creation of uniform or patterned deposition of colorants to produce desired patterns, logos, and more unique designs desired for paper goods. WOW is advantageous for integrating appearance modifiers with the pulp-derived substrate because it can concentrate the formulation to one side of the substrate, and it eliminates the need to have secondary processing.

[0045] In embodiments, the WOW process can be used to impart additional, specialized properties to a pulp-derived substrate. As an example, electromagnetic interference (EMI) shielding paper can be produced via depositing into a pulp-derived substrate formulations loaded with colloidal particles that absorb and dissipate electromagnetic waves; useful particles for this purpose can include gamma ferric oxide, nano-silver whiskers, carbon nanotubes, conductive carbon solids, and the like. EMI shielding paper can be incorporated into building and decorative materials to produce EMI- shielding wallpaper, facing paper of gypsum dry wall, and the like.

[0046] As another application, the WOW method can be used to deposit a foamable formulation onto and into partially dry pulp. Foaming of the formulation will then take place as the continuous substrate dries, typically leading to the foam adhering to the underlyingpaper sheet. In certain embodiments, the foamable formulation can be engineered so that it penetrates the paper matrix to a designated degree, so that the becomes integrated with the matrix. The composite, continuous sheet comprising the integrated foam (whether applied to the surface or absorbed into the matrix, or both) can be formed into desired shapes or objects without glues or complex production methods; as formed, the foam-containing composite material can then be slitted, punched, perforated, folded, etc. to create useful articles. Advantageously, the foam can be prepared with reinforcing additives, such as nanocellulose elements, including redispersible / redispersed nanocellulose elements described below in more detail. A pulp-derived sheet incorporating foams containing reinforcing additives can produce a lightweight material with considerable structural strength, rigidity, or other mechanical properties. For example, a pulp-derived thickened or corrugated sheet can offer an alternative for traditional corrugated boxes or other packaging materials. It can further be engineered to be lightweight, strong, compostable, etc., with tunable barrier properties. As disclosed herein, the barrier properties and other functional properties can be introduced into the material using the WOW method with appropriate formulations.

[0047] In more detail, two or more functionalities can be added to a pulp-derived substrate in a single application using the WOW process. For example, EMI shielding paper that is brightened, colored, or patterned can be produced via WOW-mediated deposition; subsequently or simultaneously, the paper can be provided with barrier properties by applying a barrier-producing formulation via the WOW process. When imparting multiple functionalities to the pulp product it is important to be aware of the order of application. For example, strengthening agents and appearance modifiers can advantageously be applied first, followed by the application of a barrier-producing formulation to produce OGWR barrier properties. Formulations to be applied to pulp-derived substrates can be augmented by inclusion of MFC / NFC in a WOW-applied spray formulation for reinforcement of the pulp matrix and for simultaneously creating OGWR barrier properties.

[0048] In embodiments, the WOW method can be employed for imparting barrier properties or other properties to meshes or other matrices formed from fibrous substrates such as pulp-based substrates, for example substrates formed with nanocellulose elements as described herein. In such embodiments, the denser pulp-based substrate material provides the foundation to which the formulations are applied, similar to the processes used with pulp- only substrates. With pulp-based substrates, WOW can be used to apply a second layer of functional additives to the surface of the substrate material. For example, a formulation providing barrier properties can be prepared, such as an emulsion comprising barrier-producing agents such as cellulose ethers or resin acids, which can be applied to the surface of the substrate; a vacuum can then be applied to facilitate the passage of the formulation from the surface into the substance of the pulp-based material. With a gradual increase in the force applied by the vacuum, the lighter emulsion droplets will be pulled into the substrate, and will slowly become trapped by the filtration action of the fibers constituting the denser pulp-based matrix material, thus producing a concentration gradient of the barrier property on the surface and within the substrate itself.

[0049] In embodiments, the WOW method can be used to add NCEs and other additive formulations having functional properties such as barrier-producing formulations to pulp- derived substrates. Advantageously, redispersible NCEs can be employed, as described below in more detail. Incorporation of NCEs into the substrate can be achieved either through initial mix-in with the pulp-derived material or through the WOW process. Mixing NCEs into the initial pulp slurry can achieve more homogenous distribution of these additives throughout the material, improving overall strength. Using the WOW process to incorporate a barrier- producing formulation into the final substrate will allow the barrier-producer to gravitate towards the external aspect of the material, where it may be more effective in providing OGWR. e. Wet-on-wet processing for nanocellulosic substrates

[0050] The WOW methods disclosed herein are applicable to the processes used to form sheets or formed articles from pulp-based substrates comprising redispersible NCEs. As described in US Patent Application Pub. No. 2022 / 0412010 (the ‘010 Application, the contents of which are incorporated herein by reference), liquid formulations can be prepared by producing suspensions of nanocellulose (NC) elements and a drying / dispersal additive, wherein the drying / dispersal additive is selected from the group consisting of temperature- responsive polymers, small molecule additives in volatile systems, and blocking agents; these liquid formulations can then be dried to form a dried NC-containing material with nanocellulose elements embedded within, wherein the redispersibility of the dried NC- containing material is greater than that of a dried control material prepared by drying a control suspension of nanocellulose elements in a liquid medium, wherein the control suspension lacks a drying / dispersal additive. Sheets or formed articles can be formed using NCEs that have been redispersed or rendered redispersible by the methods disclosed in the ‘010 Application.

[0051] In more detail, as taught in the ‘010 Application, it is understood that NC materials suitable for treatment with the systems and methods disclosed herein can be derived from all types of cellulosic raw materials, in particular plant-derived cellulosic raw materials, which can also be termed lignocellulosic materials. Lignocellulosic materials are formed of cellulose polymers as described above bound with varying amounts of lignin.Lignocellulosic materials can include virgin biomass, as is found in naturally occurring plants like trees, bushes, and grass. Lignocellulosic materials can include waste materials from consumption or from industries such as agriculture (e.g., corn stover and corncobs, sugarcane bagasse, straw, oil palm empty fruit bunch, pineapple leaf, apple stem, coir fiber, mulberry bark, rice hulls, bean hulls, soybean hulls (or “soyhulls”), cotton linters, blue agave waste, North African glass, banana pseudo stem residue, groundnut shells, pistachio nut shells, grape pomace, shea nut shell, passion fruit peels, fique fiber waste, sago seed shells, kelp waste, juncus plant stems, and the like), or forestry (saw mill and paper mill discards).Lignocellulosic materials can include specialty-purpose crops such as switchgrass and elephant grass cultivated for uses such as biofuels, capable of multiple harvests. Plants having use as lignocellulosic materials can be woody (such as trees, with firm stems, and with multiyear growth cycles) or non-woody, having weak stems and annual or limited multiyear growth cycles. Non-woody plants are particularly advantageous, typically possessing low amounts of lignin relative to the amount of cellulose they contain. As would be understood by those of skill in the art, different techniques are available for processing the various lignocellulosic materials to extract NC materials therefrom.

[0052] As taught in the ‘010 Application, additives can be used for inhibiting or disrupting the hydrogen bonding of NC materials at elevated temperatures (for example, during drying), while retaining high intrinsic hydrophilicity, thus allowing facile redispersion in aqueous media. The formulations and methods disclosed herein include several different categories of additives (termed “drying / dispersal additives”): (1) certain temperature- responsive polymers that can introduce spacing between NC particles or fibers (collectively, “NC elements”) during drying, thus preventing their clumping; (2) certain volatile small molecules that can create space between NC elements during drying; and (3) certain nonvolatile small or large molecules that hinder hydrogen bonding between or among NC elements during drying. All of these materials act to disrupt hydrogen bonding at elevated temperatures or under other circumstances, while creating gaps between or among the NC elements with further drying that will permit subsequent redispersion. As used herein, the term “drying” for an initial suspension of NC elements (termed the “initial NC suspension,”understood to be the suspension containing the NC elements that is initially produced during the defibrillation processes, as exemplified in the description that follows) refers to the application of heat and / or any other dewatering technology to the initial NC suspension that results in a decrease in the water content of the initial NC suspension so that the initial NC suspension is converted to a solid or semi-solid material comprising the NC elements that were present in the initial NC suspension. This dried solid or semi-solid material can be referred to as the “dried NC material.” As used herein, the term “redispersion” refers to a process by which the dried NC material is suspended in a fluid medium (whether aqueous or non-aqueous) so that there is a substantially complete dissolution of the dried NC material (whether semi-solid or solid) into its component NC elements. In embodiments, aqueous resuspending fluids can be used; in other embodiments, non-aqueous resuspending fluids can be used, such as fluids having hydrophobic properties or amphiphilic properties.

[0053] In embodiments, redispersion results in a suspension of the NC elements so that they are formed as individual NC elements or coalescences of individual NC elements (either, referred to herein as a “resuspended particles”) wherein such resuspended particles have an aspect ratio of greater than 10. In embodiments, the resuspended particles have an aspect ratio between about 10 and about 300, or between about 10 and about 200. In embodiments, the resuspended particles have an aspect ratio between about 50 and about 150. In embodiments, the resuspended particles have an aspect ratio between about 25 and about 75. In other embodiments, the resuspended particles have an aspect ratio between about 75 and about 125. While certain additives (for example, certain LCST polymers, as described below) are especially suitable for use as single agents for facilitating drying and redispersion, other additives lend themselves for use as adjuvants in combination with a main drying / dispersal additive, either administered into the initial NC suspension simultaneously with the main additive, or as pre-treatment to the initial NC suspension or any precursor thereof before adding the main additive, or as a post-treatment to the initial NC suspension following the addition of the main drying / dispersal additive. In addition to certain LCST polymers, drying / dispersal additives comprise, without limitation, temperature-responsive polymers, small molecule additives in volatile systems, and blocking agents.

[0054] It is understood that the drying / dispersal additives as taught in the ‘010 Application can be introduced into a NC-containing suspension individually or in combination to improve the drying process for the NC and to facilitate its redispersion. Drying / dispersal additives can also be used in combination with other agents that enhance their efficacy, even if those other agents are not effective as drying / dispersal additives whenused alone; such agents, used in combination with the drying / dispersal additives to enhance their efficacy, are termed “adjuvants.” It is further understood that one or more of the drying / dispersal additives or adjuvants can act together in a synergistic manner. Moreover, combinations of the drying / dispersal additives can be introduced sequentially during the preparation of the initial NC suspension, and / or before, after, or during the processes that are employed to produce the initial NC suspension from a feedstock of cellulosic sources, with or without the addition of adjuvants. For example, non-polymeric additives can be added during the processes that are employed to produce the initial NC suspension from feedstock, but desirably are to be added after chemical pretreatment. Processes for forming NC-containing suspensions (i.e., initial NC suspensions) suitable for treatment using the formulations and methods disclosed herein are familiar in the art. To form such a NC-containing suspension, cellulose sources can be processed using mechanical techniques and optional chemical treatments to extract the component cellulose nanomaterials and retain them as suspended in a liquid medium. The NC elements thus extracted form the initial NC suspension, which can be treated using the disclosed formulations and methods.

[0055] NCEs produced and modified as taught in the ‘010 Application can be formed into highly porous three-dimensional nanoscale networks capable of holding functional or active agents within their interstices, and capable of being engineered to optimize their own intrinsic properties with or without adding other ingredients. NCE matrices have mechanical properties due to their incorporation of the NCEs themselves in a structural framework. The matrices can thus be used as supporting or enveloping structures for formed articles that have advantageous mechanical properties such as strength and stability but that are also engineered to be dissolvable at an appropriate time for consumer use. Such matrices can be formulated as solids, gels, liquids, and the like, to meet the specific product’s needs. Moreover, the matrices, once created, can be shaped or molded into any convenient geometry, such as chips, strips, balls, cubes, sheets, etc., as required by the product category, to produce articles of manufacture. Once formed, a NCE matrix can be used as is, or can be redispersed in water or other aqueous redispersion fluids to form the final product.

[0056] In embodiments, the WOW methods disclosed herein can be used to create sheets from the aforesaid redispersible NCEs. To form such sheets, the operations and the order of operations can be similar to those employed for producing conventional pulp-derived paper sheets. NCEs can be formed into mats and dried through the mechanical press, then sprayed with the redispersion formulation or formulations as disclosed in the ‘010 Application prior to passing the mats into the thermal drying stage. Preferably, theredispersion formulation(s) are applied evenly across the surface of the NCE mat, and enough time is allowed for the formulations to spread through the NCE matrix and permeate the substrate. In embodiments, a double-sided spray can be employed to facilitate equal distribution of the redispersion formulation(s) throughout the substrate. Advantageously, the NCE sheet being treated with the redispersion formulation(s) should be thin enough for those additives to diffuse easily and thoroughly throughout the substrate.

[0057] In embodiments, other additives can be distributed throughout the NCE sheet using the WOW method at the same time that the redispersion formulation(s) are being added. For example, redispersion formulations and surfactants can be simultaneously deposited from the spray nozzle onto thin NCE sheets to produce redispersible soap sheets. Detergent ingredients along with redispersion formulations can be deposited to produce redispersible laundry sheets.EXAMPLES

[0058] Example 1 : Molded pulp fiber product coated with additive formulation

[0059] Additive formulation preparation for WOW processing:

[0060] The following materials were used in the preparation of the additive formulation:• Sigma Aldrich Sodium Carboxymethyl cellulose (NaCMC)• Sappi Valida L 3% Nanofibrilated cellulose (NFC)• Bagasse market pulp: the pulp that is being used for the purpose of this experiment is a market blend bagasse pulp.

[0061] Using the materials enumerated above, an additive formulation for use in WOW processing was prepared having a combined solids content of 0.1375% solids. To prepare this formulation, NaCMC and NFC were combined in a ratio of 1 : 10 on a dry basis as follows: 0.1 gm of NaCMC was weighed out and solubilized in 766 gm tap water, being mixed on a magnetic stir plate to form a NaCMC mixture; 33.3 gm of NFC was weighed out and added to the NaCMC mixture after the NaCMC had been fully solubilized, and the NFC was mixed into the NaCMC mixture until fully homogeneous.

[0062] Molded fiber production:

[0063] A target GSM of 6500 GSM was selected for the molded pulp fiber being produced during this experiment, consistent with advantageous coating and OGRperformance of the molded fiber product. The mold shape used was a 3” diameter flat disk mesh (No. 40) sieve, having a target weight of 30 g for the coating to be applied. A 0.5% consistency pulp slurry was prepared by mixing the bagasse pulp in water.

[0064] The 3” mesh sieve was inserted into a Buchner funnel, and the edges were sealed with waterproofing tape. The vessel was connected in series with a collection basin and a vacuum pump. An initial pulp substrate was then prepared by submerging the 3” sieve into the 0.5% consistency pulp slurry, and a vacuum was applied. During this initial forming, the slurry was pulled through the sieve, leaving the pulp to form a substrate in the shape of the mesh mold and allowing the water to pass through and collect in the collection basin. To reach a target weight of the fully dried pulp sample, the sieve was removed from the pulp slurry after 5 seconds. Once the sieve was removed, the remaining pulp substrate on the mesh had a solids content of about 20% to 30%. The sieve and the pulp substrate were kept under constant vacuum thereafter.

[0065] In the experimental set-up, the vacuum pump, collection basin, and sieve were arranged on a transverse platform that moved back and forth under a stationary spray nozzle. The sieve was placed on a stand on the platform it was removed from the pulp slurry, so that it was centered below the spray nozzle while the pulp substrate on the sieve was being dried via the vacuum. Separately, the additive formulation described above was placed in a pressurized vessel that was connected to the spray nozzle.

[0066] After the initial pulp substrate was formed, with the vacuum still applied, the sieve was placed on the stand below the spray nozzle. The spray nozzle was turned on and the transverse platform was moved so that the spray plume traversed the surface of the sieve and completely coated the surface of the pulp substrate. The spray nozzle used for the experiment was a flat spray. Its height had been optimized so that the spray plume that hit the pulp surface was 3” wide, to completely cover the pulp substrate.

[0067] During this process, the additive formulation was sprayed onto the semi-wet 20-30% solids content pulp substrate while the vacuum was constantly applied, forming a single treated pulp substrate. The speed and liquid pressure of the additive formulation spraying were optimized so that 30 g of the additive formulation was deposited on the surface of the pulp substrate. The vacuum was applied during the spraying process and for 20 seconds post spraying to allow for full absorption of the additive formulation into the pulp substrate. Because the sieve and the pulp substrate are continuously exposed to thevacuum, once the spray is applied the additive formulation begins to absorb immediately into the pulp substrate and diffuse into it, forming a single treated pulp substrate.

[0068] After removing the vacuum, the treated pulp substrate was removed and fully dried via thermoforming methods. The fully dried sample could then be termed a treated sample, with the treated surface being the one to which the spray had been applied.

[0069] Results:

[0070] After thermoforming, the 3” disks had an additive layer clearly visible on the target surface. The target surface was glossy and less textured than the bottom, mesh side of the sample. The treated surface also had a brighter, white color than the untreated side.

[0071] Since the additive formulation had been prepared in order to impart OGR properties to the treated sample, the following observational test was carried out to assess the OGR performance following treatment: 1 ml of vegetable oil was dropped onto the surface of the experimental sample with a pipette and its effect on the sample was observed and compared to the effect of a similar oil exposure on a control sample. The untreated (control) sample began to absorb the oil almost immediately after it touched the surface; this was indicated by an immediate change in color of the sample surface as well as seeing the oil droplet move into the sample. In contrast, the treated (experimental) sample did not absorb the oil dropped on its surface. Instead, the oil remained on the surface of the treated sample for several minutes without causing any discoloration. The oil could be wiped off easily and thoroughly with an absorbent cloth, after which the treated sample appeared as though it had not been exposed to the oil, with no visual oil absorption.EQUIVALENTS

[0072] Unless otherwise indicated, all numbers expressing reaction conditions, quantities, amounts, ranges and so forth, as used in this specification and the claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.

[0073] Furthermore, the invention encompasses all variations, combinations, and permutations in which one or more limitations, elements, clauses, and descriptive terms from one or more of the listed claims is introduced into another claim. For example, any claim that is dependent on another claim can be modified to include one or more limitations foundin any other claim that is dependent on the same base claim. Where elements are presented as lists, e.g., in Markush group format, each subgroup of the elements is also disclosed, and any element(s) can be removed from the group. It should be understood that, in general, where the invention, or aspects of the invention, is / are referred to as comprising particular elements and / or features, certain embodiments of the invention or aspects of the invention consist, or consist essentially of, such elements and / or features. For purposes of simplicity, those embodiments have not been specifically set forth in haec verba herein. It is also noted that the terms “comprising” and “containing” are intended to be open and permits the inclusion of additional elements or steps. Where ranges are given, endpoints are included. Furthermore, unless otherwise indicated or otherwise evident from the context and understanding of one of ordinary skill in the art, values that are expressed as ranges can assume any specific value or sub-range within the stated ranges in different embodiments of the invention, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise.

[0074] While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

CLAIMS1. A method for treating a substrate comprising a lignocellulosic fibrous material with an additive formulation, the method comprising: providing the substrate to be treated; partially drying the substrate; applying the additive formulation to the substrate before the substrate has completely dried, thereby forming a treated substrate; and subjecting the treated substrate to a reduced pressure environment before the treated substrate has completely dried, wherein the reduced pressure environment impels the additive formulation into the treated substrate at a preselected concentration or along a preselected concentration gradient.

2. The method of claim 1, wherein the substrate is a pulp-derived substrate.

3. The method of claim 2, wherein the pulp-derived substrate is a pulp-derived nanocellulosic substrate.

4. The method of claim 1, wherein the lignocellulosic fibrous material is a plant-based waste material.

5. The method of claim 4, wherein the plant-based waste material is an agricultural waste material or a forestry waste material.

6. The method of claim 1, wherein the lignocellulosic fibrous material is a material from a special-purpose crop.

7. The method of claim 1, wherein the lignocellulosic fibrous material is a whole plant material.

8. The method of claim 1, wherein the additive formulation comprises an additive selected from the group consisting of a barrier-producing additive, a mechanicalmodifying additive, an appearance-modifying additive, and a specialized additive.

9. The method of claim 8, wherein the additive is the barrier-producing additive, and wherein the barrier-producing additive produces at least one of oil and grease resistance and water resistance.

10. The method of claim 9, wherein the barrier-producing additive comprises methylcellulose and rosin.

11. The method of claim 10, wherein the barrier-producing additive further comprises nanocellulose elements.

12. The method of claim 1, wherein the step of applying takes place before commencing the step of partially drying.

13. The method of claim 12, wherein the step of applying comprises mixing the additive formulation into the substrate.

14. The method of claim 1, wherein the step of applying comprises applying the additive formulation to a surface of the substrate.

15. The method of claim 14, wherein the step of applying comprises a spray-on processing method.

16. The method of claim 1, wherein the step of partially drying is commenced following the commencement of the step of subjecting.

17. The method of claim 1, further comprising modifying the reduced pressure environment during the step of subjecting, to modify the preselected concentration or a preselected concentration gradient at one or more preselected time intervals.

18. The method of claim 1, further comprising the step of completely drying the treated substrate following the step of subjecting.

19. The method of claim 18, further comprising applying a second additive formulation to the treated substrate following the step of subjecting and before the step of completely drying, thereby producing a twice-treated substrate.

20. The method of claim 19, wherein the second additive formulation comprises a second additive that differs from the additive in the additive formulation applied to the substrate.

21. The method of claim 19, wherein the additive formulation is mixed into the substrate to form the treated substrate, and the second additive formulation is applied to the surface of the treated substrate.

22. The method of claim 19, further comprising a step of subjecting the twice-treated substrate to a second reduced pressure environment before the step of completely drying, wherein the second reduced pressure environment impels the second additive formulation to penetrate the twice-treated substance at a second preselected concentration or along a second preselected concentration gradient.

23. The method of claim 19, wherein the step of applying the second additive formulation takes place by exposing the treated substrate to an applicator that bears or contains the second additive formulation, wherein the applicator applies the second additive formulation to a surface of the treated substrate to produce a treated surface.

24. The method of claim 23, wherein the applicator comprises an internal reservoir.

25. The method of claim 23, wherein the applicator applies the second additive formulation by contacting the treated substrate, thereby producing the treated surface.

26. The method of claim 23, wherein the applicator dispenses the second additive formulation while remaining at a designated distance from the treated substrate, thereby producing the treated surface.

27. The method of claim 26, wherein the designated distance varies over time, with a consequent variation in amount of second additive formulation dispensed onto the treated surface over time.

28. The method of claim 23, wherein the applicator is pre-formed to conform to an external shape of the treated substrate.

29. The method of claim 23, wherein the applicator is flexible and conforms to the external shape of the treated substrate after contacting it.

30. The method of claim 29, wherein the applicator is formed from an article selected from the group consisting of a sheet, an absorbent meshwork, a foam, and a sponge.

31. The method of claim 23, wherein the applicator comprises a non-absorbent sheet placed in close proximity to the treated substrate, wherein the second additive formulation is directed into and through a space between the non-absorbent sheet and the treated substrate.

32. The method of claim 23, wherein the applicator applies the second additive formulation to the surface of the treated substrate by directing the second additive formulation to pass from an external, non-delivery surface of the applicator into and through the applicator, wherein the applicator is in an effective proximity to the treated substrate.

33. The method of claim 32, wherein the effective proximity comprises a contact between the applicator and the treated substrate.

34. The method of claim 33, wherein the contact is a partial contact.

35. A method of producing a three-dimensional formed article, comprising: producing the twice-treated substrate by the method of claim 19 and molding the twice-treated substrate to produce the three-dimensional formed article.

36. A method of producing a flat two-dimensional article, comprising: producing the twice-treated substrate by the method of claim 19, wherein the additive formulation is applied to the substrate in a wet end of substrate processing, and shaping the twice-treated substrate to form the flat two-dimensional articlefollowing the step of subjecting the twice-treated substrate to the reduced pressure environment.