SYSTEMS AND METHODS FOR MAKING A DELIGNIFIED PAPER POUCH, CONTAINER, OR SEALING STRUCTURE

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Application No. 63/637,711, filed on Apr. 23, 2024, and entitled “Systems and Methods for Making a Delignified Paper Bag, Container, or Sealing Structure,” the entire contents of which is incorporated by reference herein in its entirety.

REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

SEQUENTIAL LISTING

Not applicable

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

The present disclosure generally relates to systems and methods for making a delignified paper bag or container made partially or entirely of repulpable and/or recyclable paper, and more particularly to delignified paper pouches and containers with sealing structures that are also or alternatively made of repulpable and/or recyclable paper.

2. Description of the Background of the Invention

Historically, re-closeable pouches and containers (collectively “bags”) that are used in food and household storage and packaging comprise one or more of a folded web of elastomeric material, a web formed of blown, cast, monolayer, or co-extruded films, or a silicone-based mixture that may be liquid injection molded, all of which generally have two side walls that are connected along the bottom and opposing sides. The bags typically include a re-closable fastener or closure system at a top of the bag, such as, for example, an adhesive, a wire tie, or zipper. While thermoplastic and elastomeric bags have a variety of benefits, including reduced cost and ease of manufacture, efficient packaging and transport, and desirable sealing capabilities for end use, such bags are not recyclable or repulpable, and given consumer trends related to recyclable and repulpable packaging, new and improved bags are desired that maintain the benefits associated with prior art bags.

It is therefore desirable to maintain or enhance the benefits of prior art bags through the use of materials that are configured to be recycled or repulped, i.e., by using one or more sustainable materials. It is further desirable to optimize sealing structures used with such repuplable and/or recyclable bags, pouches, or containers, including by having a simple sealing structure that is capable of providing an optimized seal for the intended use of each particular bag and that can be used in various rigorous applications.

Furthermore, the current state of the art in paper bags or products focuses on the repulpability of the product rather than the recyclability. Creating a recyclable paper bag or product would address the consumer desire for a more sustainable product.

SUMMARY OF THE DISCLOSURE

According to some embodiments, a pouch made of cellulose-based materials includes a body defining a left side, a right side, a bottom side, and a mouth at an upper end thereof that provides access into a cavity of the pouch, and a sealing structure that is configured to allow access into the cavity of the pouch in an open configuration and to prevent access into the cavity of the pouch in a closed configuration. The sealing structure and/or body of the pouch comprises at least 85% of at least one repulpable material comprising plant-based cellulose, wherein the pulp or repulpable material is at least 10% delignified, and a remaining percentage of the pouch may consist of a polymer.

In some embodiments, the plant-based cellulose material includes an organic material selected from the group consisting of wood pulp, paper fibers, cotton, linen, silk, wool, wheat straw, sugar cane waste, flax, bamboo, wood, linen rags, esparto, manilla, jute, palm fiber, mulberry, coconut husk, agave, reed grass, and hemp. In some embodiments, a polymer component consists of one or polyolefins, hexanes, poly(lactic acid), chitosan, polycarbonates, polyimides, polysiloxanes, acrylic polymers, polybenzoxazines, polyvinyl acetates, polyethylene, polystyrene, polyvinyl acetate copolymers, ethylene-maleic anhydride copolymers, polyacrylates, polyethers, styrene-maleic anhydride, cellulosic ethers, alkali-soluble polyvinyl acetate copolymers, ethylene-maleic anhydride copolymers, polyvinyl alcohol, ethylene vinyl alcohol, polyvinyl pyrrolidone, hydroxyethylcellulose, methycellulose, sodium carboxymethylcellulose and combinations thereof. In some embodiments, the sealing structure and/or body comprises at least 85% cellulose-based material wherein the repulpable material is at least 10% deligninfied.

In additional embodiments, a pouch made of cellulose-based materials includes a body defining a left side, a right side, a bottom side, and a mouth at an upper end thereof that provides access into a cavity of the pouch, and a sealing structure that is configured to allow access into the cavity of the pouch in an open configuration and to prevent access into the cavity of the pouch in a closed configuration. In some embodiments, the sealing structure of the pouch comprises at least 85% of at least one repulpable material comprising plant-based cellulose, wherein the repulpable material is at least 10% delignified, and a remaining percentage of the pouch may consist of a polymer. In some embodiments, the body of the pouch comprises at least 85% of at least one repulpable material comprising plant-based cellulose, wherein the repulpable material is at least 10% delignified, and a remaining percentage of the pouch may consist of a polymer. In some embodiments, the sealing structure and body of the pouch comprise at least 85% of at least one repulpable material comprising plant-based cellulose, wherein the repulpable material is at least 10% delignified, and a remaining percentage of the pouch may consist of a polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a recyclable and/or repulpable pouch with a first sealing structure shown in an open configuration, as disclosed herein;

FIG. 2 is a schematic view of the pouch of FIG. 1 with the first sealing structure shown in a closed configuration;

FIG. 3 is a side cross-sectional view of a second sealing structure including a male portion and a female portion shown in an open configuration; and

FIG. 4 schematically illustrates a method or process of making the sealing structures described herein.

Other aspects and advantages of the present disclosure will become apparent upon consideration of the following detailed description, wherein similar structures have similar reference numerals.

DETAILED DESCRIPTION

The present disclosure is directed to pouches and containers (collectively “bags”), and the associated sealing structures for the pouches that are made either entirely or partially from repulpable and/or recyclable materials, such as paper. More specifically, the present disclosure is directed to a repulpable and/or recyclable, re-closeable pouch, a repulpable sealing structure for a re-closeable pouch, and a method of making a repulpable and/or recyclable pouch and sealing structure therefor. While the systems and methods disclosed herein may be embodied in many different forms, several specific embodiments are discussed herein with the understanding that the embodiments described in the present disclosure are to be considered only exemplifications of the principles described herein, and the disclosure is not intended to be limited to the embodiments illustrated.

Throughout the disclosure, the terms “about” and “approximate” mean plus or minus 5% of the number or value that each term precedes. As used herein, the phrase “leak resistant seal” refers to a seal that resists leakage of liquids and solids from the container during storage and transport without the aid of an external structure to maintain the seal. Finally, the term “closure element” is defined herein to mean one part of a closure system that is configured to close a pouch. The closure system may comprise a sealing structure used to seal the pouch, wherein the sealing structure comprises one or more closure elements. For example, on a zipper closure, a closure element is one profile or the other of the zipper, e.g., a rib profile or a groove profile.

The pouches and sealing structures disclosed herein may be entirely or partially repulpable and/or recyclable. The pouches may take varying forms, and representative examples are provided in FIGS. 1-3. As used herein, the term “repulpable” or “repulpable material” refers to a cellulose material whose fibers can be broken down and returned to the pulp state and suspended in a liquid such as water, i.e., material that can undergo the operation of re-wetting and fiberizing for subsequent sheet formation. The dissociated fibers can then be re-used (e.g., re-combined) to make a new cellulose material. Examples of repulpable materials include various papers, cardboards, and other cellulose-based materials. The sealing structures disclosed herein enable production of fully repulpable and/or recyclable flexible packages that can be opened and re-closed by a consumer. In some embodiments, the sealing structure may include a repuplable pressure sensitive adhesive.

As further used herein, “recyclable” material means “used material that is capable of being processed into new paper or paperboard.” A paper product that is recyclable must be repulpable, but a paper product that is repulpable is not always recyclable. Repulpability may be tested through a method of blending paper material with water into a pulp, filtering the pulp, and determining how much fiber can be recovered. Recyclability may be tested by pulping the paper product and converting it into a new sheet that is then put through a series of quality tests to validate both properties and appearance.

The advantages of the repulpable and/or recyclable pouches disclosed herein are: 1) improved environmental performance; 2) waste is eliminated since the leftover pouches do not have to be disposed of and less material is wasted in the mixing process, and 3) material utilization is improved since all the material in the pouch ends up in the mixer and none otherwise enters into the environment. The paper comprising the pouches may include kraft paper, twisted paper, greaseproof paper, recycled paper, coated paper, cotton, offset paper, paperboard, duplex paper, or combinations thereof. In some embodiments, repulpable tape may be included, which may comprise water soluble modified acrylic adhesive, coated on a repulpable paper carrier, such that the repulpable tape's backing and glue can be dissolved in water. In some embodiments, recyclable tape may be utilized.

As noted above, the pouches and sealing structures of the present disclosure are made of paper or paper-like materials, and in some embodiments are made using a pulp/binder mixture. In some embodiments, the sealing structure is a zipper that includes a male profile and a female profile. The details of the sealing structure may be modified based on a user's intended use and are not limited to the embodiments disclosed herein. While the ratio of the pulp/binder mixture may be modified based on intended use, in some embodiments more than 50% of the mixture comprises repulpable material or a similar substance, e.g., potato fibers, vegetable fibers, or other organic fibers. In some embodiments, more than 20%, or more than 30%, or more than 40%, or more than 60%, or more than 70%, or more than 80% or more than 90% may comprise the repulpable material or similar substances. The repulpable material may comprise one or more different types of organic materials that may be made from cellulose, tannin, cutin, pectin, chitin, and/or lignin. The organic material may come from various plants, including cotton, wheat straw, sugar cane waste, flax, bamboo, wood, linen rags, esparto, manilla, jute, palm fiber, mulberry, coconut husk, agave, reed grass, and/or hemp. In some embodiments, the end pulp/binder mixture is configured to be heat resistant up to 451° F. (232° C.), freezer capable, and oven and microwave resistant. Preferably, the pulp/binder mixture in its end form is water and oil resistant. In some embodiments, the binder is entirely made from or includes RTU silicone. In some embodiments, the zipper profile is separately combined with and/or joined to a paper pouch to make a fully recyclable paper pouch product.

As used herein, lignin is defined as a complex aromatic polymer that comprises about 20% to 40% of wood where it occurs as an amorphous polymer. Lignins can be grouped into three broad classes, including softwood or coniferous (gymnosperm), hardwood (dicotyledonous angiosperm), and grass or annual plant (monocotyledonous angiosperm) lignins. Softwood lignins are often characterized as being derived from coniferyl alcohol or guaiacylpropane (4-hydroxy-3-methoxyphenylpropane) monomer. Hardwood lignins contain polymers of 3,5-dimethoxy-4-hydroxyphenylpropane monomers in addition to the guaiacylpropane monomers. The grass lignins contain polymers of both of these monomers, plus 4-hydroxyphenylpropane monomers. Hardwood lignins are much more heterogeneous in structure from species to species than the softwood lignins when isolated by similar procedures.

In some embodiments, the pouch and/or the sealing structure may be repulpable, recyclable, or repulpable and recyclable. Further, one or more adhesives may be used along the pouch and/or the sealing profile, which may also be repulpable, recyclable, or repulpable and recyclable. In some embodiments, the pouch may be customized by printing one or more indicia on one or both of the first and second opposing walls at predetermined intervals. Indicia may include, e.g., logos, writable surfaces, volumetric fill lines or other indicators, etc. Indicia may be applied at various stages during the manufacturing process. In still another aspect, indicia may not be applied to the pouch. In yet another aspect, customizing may include adding sliders, stickers, embossing, scoring, or other decorative and/or functional attributes to the pouch.

In some embodiments, the pouch may include a fold top closure, a slider sealer, a hook-and-loop-type sealer, or an adhesive to at least partially seal a mouth of the pouch. In some embodiments, a tab disposed adjacent the mouth may assist in opening the pouch. Additionally, as would be appreciated by those of ordinary skill in the pertinent art, the subject technology is applicable to any type of bag, pouch, package, and various other storage containers, e.g., snack, sandwich, quart, and gallon size pouches. The subject technology is also adaptable to pouches having a double zipper, multiple zippers, or other types of closure mechanisms.

In some embodiments, the ratio of fiber to another material may be 85% fiber compared with 15% of a different material, which achieves a repulpable material. In some embodiments, more than 90% fiber may be utilized, which renders the pouch recyclable. A repulpable formulation for the pouches disclosed herein may include a blend of a polymer and repulpable material comprising plant-based cellulose. As noted above, a formulation range of 15% or less of the polymer enables ease of repulpability and maintains recyclability with current recycling streams, which require 85% recovered repulpability. However, use of more than 90% plant-based cellulose material increases recyclability and composability of the product, due to the higher ratio of fiber content to polymer. In some embodiments, the ratio of fiber to another material may be around 100% fiber compared with a negligible amount of a different material.

The closure elements disclosed herein can include any suitable polymer or binder that can be mixed with the repulpable material comprising plant-based cellulose. When present, the closure element can be formed using the same polymer as the remainder of the pouch or can be formed using a different polymer. Suitable repulpable materials comprising plant-based cellulose include wood pulp, paper fibers, cotton, linen, silk, wool, combinations thereof, and/or any of the plant-based materials listed above. While other (e.g., non-cellulose) materials may qualify as repulpable, the plant-based cellulose materials, combined with suitable amounts of a polymer, contribute mechanical and structural properties that are helpful in some embodiments to maintain the structural integrity of the closure element.

To that end, the materials used to form the pouch and/or the one or more closure elements may fall into the same two categories. The first category includes polymers which may act as a binding material for the repulpable materials comprising plant-based cellulose. The second category includes repulpable and recyclable materials, such as plant-based cellulose materials that are intended to replace disposable non-repulpable/recyclable plastic packages. The pouches disclosed herein can include between about 5% and about 95% by weight of a polymer and between about 5% and about 95% by weight of a repulpable and/or recyclable material. In some embodiments, the pouch and/or one or more closure elements can include between about 10% and about 90% by weight of a polymer and between about 10% and about 90% by weight of a repulpable and/or recyclable material, or between about 15% and about 85% by weight of a polymer and between about 15% and about 85% by weight of a repulpable and/or recyclable material. In embodiments that include a repulpable zipper, the zipper is movable between a first open position that disengages the at least one interlocking element adapted for connection to the front wall from the at least one interlocking element adapted for connection to the second wall and a second closed position that engages the at least one interlocking element adapted for connection to the front wall to the at least one interlocking element adapted for connection to the second wall.

The polymers may include any polymer combinations that are useful, including polyolefins, hexanes, poly(lactic acid), chitosan, polycarbonates, polyimides, polysiloxanes, acrylic polymers, polybenzoxazines, polyvinyl acetates, polyethylene, polystyrene, polyvinyl acetate copolymers, ethylene-maleic anhydride copolymers, polyacrylates, polyethers, styrene-maleic anhydride, cellulosic ethers, alkali-soluble polyvinyl acetate copolymers, ethylene-maleic anhydride copolymers, polyvinyl alcohol, ethylene vinyl alcohol, polyvinyl pyrrolidone, hydroxyethylcellulose, methycellulose, sodium carboxymethylcellulose, and combinations thereof. In some embodiments, the polymer used to form the body of the pouch (i.e., the front wall and the back wall thereof) can be the same polymer or polymer combination used to form the one or more closure elements or can be a different polymer or polymer combination.

Polyolefins consist of group of polymers derived from olefins (alkenes), including polyethylene (PE) and polypropylene (PP). Polyethylene is widely used and available in several forms, including low-density polyethylene (LDPE), high-density polyethylene (HDPE), and ultra-high-molecular-weight polyethylene (UHMWPE), each with distinct properties like flexibility, strength, and chemical resistance. Polyolefins have been used in products from plastic pouches to industrial pipes.

Hexanes refer to hydrocarbons that contain six carbon atoms (C₆H₁₄). Hydrocarbons are saturated compounds made up only of carbon and hydrogen atoms. The straight-chain form, n-hexane, is the most common form found in hexane solvent mixtures, though the mixture can contain branched isomers including but not limited to isohexane and neopentane. These isomers have the same molecular formula but differ in the arrangement of their carbon atoms, which affects their boiling points and solvent properties. Hexanes can be derived from crude oil and are often used for cleaning, extracting, and purifying other polymer materials in industrial settings.

Poly(lactic acid) (PLA) consists of biodegradable and bioactive thermoplastic polyester derived. PLA can be derived from renewable resources like corn starch or sugarcane. PLA is made in varying grades such as amorphous PLA, crystalline PLA, high molecular weight PLA, low molecular weight PLA, plasticized PLA, and blended PLA. These grades are typically classified based on their intended use which includes uses such as biodegradable packaging, fibers, and medical sutures, with properties influenced by factors like molecular weight and polymerization method.

Chitosan consists of a biopolymer derived from chitin, generally found in the shells of crustaceans. Chitosan derivatives can include N-acyl chitosans for different biomedical applications, and modified forms are used in food preservation due to its antimicrobial properties.

Polycarbonates consist of a group polymers made from the reaction between monomers including bisphenol A (BPA) and phosgene or other carbonyl compounds, forming a structure with repeating carbonate groups (—O—C(═O)—O—) in the polymer main chain. Exemplary polycarbonates include bisphenol A-based polycarbonate (BPA-PC) and cyclohexane-based polycarbonate.

Polyimides refer to a group of polymers with a distinctive structure with imide groups (—C(═O)—N—C(═O)—) in their polymer main chain. These can be synthesized from different diamines and dianhydrides, with variations like PMDA-ODA (polyamide-imide).

Polysiloxanes (silicones) refer to a group of polymers with a polymer main chain composed of alternating silicon and oxygen atoms. Silicones can be crosslinked to form elastomers, or processed into liquids and gels for use in a wide range of applications, including offering flexibility, water resistance, and high thermal stability for food packaging.

Acrylic polymers refer to a group of polymers made from acrylic monomers. The monomers are derived from acrylic acid or its derivatives like methacrylic acid. Acrylic polymers can also be copolymerized with comonomers including butyl acrylate or styrene to improve impact resistance and flexibility. Exemplary acrylic polymers include poly(methyl methacrylate) (PMMA), also known as acrylic glass or Plexiglas®, and other copolymers made by combining different acrylic monomers. Acrylic polymers can be flexible or rigid depending on their formulation and are used for their optical clarity, UV stability, and resistance to weathering.

Polybenzoxazines refers to a group of thermosetting polymers derived from benzoxazine monomers. These polymers are known for their high thermal stability and excellent mechanical properties. Polybenzoxazines may be synthesized via condensation reactions involving phenolic resins and amine-based monomers and are used in high-performance composites.

Polyvinyl acetates (PVAc) refer to polymers derived from vinyl acetate monomer. These polymers are commonly used in adhesives, paints, and coatings due to their film-forming properties. PVAc variants, such as polyvinyl acetate emulsions, are used in wood adhesives and paper coatings.

Polystyrene (PS) refers to a polymer derived from monomers of the aromatic hydrocarbon styrene. Polystyrene is a versatile thermoplastic polymer often used for disposable items like cutlery, containers, and packaging. Polystyrene can be expanded (EPS) to create lightweight foam products or crystal (rigid) for transparent applications, depending on the processing method.

Polyvinyl acetate copolymers refer to a group of copolymers made by combining polyvinyl acetate with other monomers. The inclusion of monomers like ethylene or acrylic acid can modify the properties, making them suitable for adhesives, paints, coatings, and emulsions with enhanced water resistance and durability.

Ethylene-maleic anhydride copolymers refer to a group of copolymers that combine ethylene and maleic anhydride. These polymers can be used in coatings, adhesives, and as impact modifiers in plastics. These polymers can also be grafted ethylene-maleic anhydride copolymers which can be used for improving adhesion of the polymer coating to other substrates.

Polyacrylates refer to a group of polymers derived from acrylic acid or acrylate esters. These monomers often include compounds like methyl acrylate, ethyl acrylate, butyl acrylate, and other acrylate esters. Polyacrylates are commonly used in applications requiring flexibility, adhesion, and water resistance.

Polyethers consist of a polymer characterized by repeating ether linkages (—O—) in their main chain. These polymers can be formed through the polymerization of monomers containing ether groups, such as ethylene oxide or tetrahydrofuran (THF). These polymers can also be blended with other polymers including polyurethane to create flexible foams or block copolymers.

Styrene-maleic anhydride copolymers refer to polymers that combine styrene and maleic anhydride. These polymers are used in engineering plastics, adhesives, and coatings. Styrene-maleic anhydride copolymers can be further modified with glycol or amide for improved use in blends, coatings, adhesives, and emulsion formulations.

Cellulosic ethers refer to polymers derived from cellulose, a natural polymer. Derivatives include hydroxypropyl cellulose and carboxymethyl cellulose (CMC) which offer various modifications for increased solubility and viscosity. Cellulosic ethers can be used in food packaging primarily for their film-forming, biocompatible, and biodegradable properties.

Alkali-soluble polyvinyl acetate copolymers refer to a group of polymers that are made by copolymerizing polyvinyl acetate (PVAc) with other monomers, such as acrylic acids or other functional groups. These modified polyvinyl acetate copolymers have increased solubility in alkaline solutions. They may be used in adhesives, coatings, and paints. Since alkali-soluble PVAc copolymers can be modified to dissolve under specific conditions, they might be used to create packaging that is more easily processed or removed after use. For example, an alkali-soluble packaging film could be designed to dissolve in a specific solution, reducing waste and making disposal more sustainable. Alkali-soluble polyvinyl acetate copolymers can also be used in food packaging materials to create barriers that prevent the loss of moisture, oxygen, or other contaminants.

Polyvinyl alcohol (PVA) refers to water-soluble polymers made from the hydrolysis of polyvinyl acetate. PVA can be used in a variety of applications, including as a film former, in adhesives, and in food packaging due to its film-forming and adhesive properties, as well as its biodegradability.

Ethylene vinyl alcohol (EVOH) refers to a copolymer of ethylene and vinyl alcohol, known for its gas barrier properties. EVOH is used in packaging applications to preserve food and prevent the diffusion of gases and can blended with other polymers like polyethylene to improve processability and barrier characteristics.

Polyvinyl pyrrolidone (PVP) refers to a polymer of made from the polymerization of vinyl pyrrolidone, a monomer derived from 2-pyrrolidone. PVP is a water-soluble polymer with a variety of molecular weights. In food packaging, PVP can be used for creating edible films, coatings, and biodegradable packaging, as well as for controlled release of active ingredients. Its ability to stabilize and form protective barriers helps enhance food quality.

Hydroxyethylcellulose refers to a water-soluble derivative of cellulose that is used as a thickener. Methylcellulose is another cellulose derivative used as a thickening agent or emulsifier. Sodium Carboxymethylcellulose (CMC) is a cellulose derivative used as a thickener, stabilizer, and binder.

Maintaining functionality and structural integrity during water-based food storage has been of particular interest for plant-based repulpable pouches and closure elements. The temperature of the water-based food, especially heat, can often damage the structural integrity of repulpable, recyclable pouches and closure elements, and therefore using strong repulpable, recycleable materials is of particular interest to improve heat resistance. In some embodiments, the temperature of the water-based food varies from a range of −20° F. (−29° C.) to 212° F. (100° C.) while maintaining structural integrity and functionality of the sealing structure and pouch. In some embodiments, the end pulp/binder mixture is configured to be heat resistant up to 451° F. (232° C.), freezer capable, and oven and microwave resistant. Preferably, the pulp/binder mixture in its end form is water and oil resistant. In some embodiments, the zipper 124 is separately combined with and/or joined to a paper pouch to make a fully recyclable paper pouch product.

Lignin provides structural support and rigidity, giving plants strength and the ability to withstand environmental stresses. Lignin is a component in maintaining the physical structure of plants, but when it comes to certain applications, like food packaging, it can present challenges because it can cause the material of the package to be more brittle and less flexible over time, making it prone to cracking or breaking. Removing lignin from a repulpable material intended for food packaging can improve various aspects including surface quality. Lignin can create a rougher, more inconsistent surface texture in plant-based materials. When lignin is removed, the material surface can become smoother and more uniform. This improvement in surface quality can be important for packaging used in food products, as a smoother surface allows for more efficient coating or lamination, reducing the likelihood of imperfections. A refined surface helps maintain the integrity of the packaging and enhances its overall appearance, making it more appealing to consumers. When lignin is removed, the resulting deligninfied material can be more flexible and less prone to cracking or breaking. This improvement in durability ensures that food packaging remains intact during transport and handling, offering better protection for the contents. Materials with reduced lignin content are less likely to deteriorate or lose their strength, which can extend the shelf life of the packaging and the food it contains. Additionally, lignin can contain compounds that may impact the safety and quality of food packaging, such as aromatic alcohols and aldehydes. These compounds can potentially migrate into food, leading to contamination as lignin breaks down over time. When lignin is removed from materials used for food packaging, it helps eliminate these potential contaminants.

Removal of lignin from the pulp can provide a densified wood or densified pulp with increased strength. As used herein, “densified wood,” “densified wood pouch,” or “densified sealing structure” are used interchangeably and refer to a processed wood material with increased strength, toughness, and density compared to a wood pouch or sealing structure that has not been similarly processed. In some embodiments, the densified wood pouch or sealing structure has a density between about 1.1 g/cm³ and about 1.9 g/cm³. In some embodiments, the densified wood pouch or sealing structure has a density of about 1.5 g/cm³. In some embodiments, the densified wood panel is delignified and at least 30% of the lignin has been removed relative to the lignin content of natural wood prior to delignification. In some embodiments, the densified wood panel has been treated with a chemical to increase hydrophobicity, weatherability, corrosion resistance, or flame resistance.

Suitable methods for the formation of densified wood from natural wood are known and described in the art. See, for example, WO 2019/055789, WO 2018/191181, and Song et al. (“Processing bulk natural wood into a high-performance structural material,” Nature, 2018, 554:224-228), each of which is incorporated herein by reference as if put forth in their entirety.

In some embodiments of the present disclosure, the densified wood pouch or sealing structure is made by a process including a first step of contacting bulk natural wood with a sodium based chemical solution for a time and under conditions sufficient to remove lignin and hemicellulose from the natural wood and form delignified wood. The sodium based chemical solution can include chemicals used in pulping or pulp bleaching such as, but not limited to, NaOH, NaOH/Na₂S, NaHS0₃+S0₂+H₂0, NaHSCb, NaHS0₃+Na₂S03, NaOH+Na₂S0₃, Na₂S0₃, NaOH+AQ, NaOH/Na₂S+AQ, NaHS0₃+S0₂+H₂0+AQ, NaOH+Na₂S0₃+AQ, NaHS0₃+AQ, NaHS0₃+Na₂S0₃+AQ, Na₂S0₃+AQ, NaOH+Na₂S+Na₂S_n, Na₂S0₃+NaOH+CH₃OH+AQ, CH₃OH, C₂H₅OH, C₂H₅OH+NaOH, C₄H₉OH, HCOOH, CH₃COOH, CH₃OH+HCOOH, C₄H₈0₂, NH₃.H₂0, p-TsOH, H₂0₂, NaCIO, NaC10₂+acetic acid, C10₂, and Cl₂, where n is an integer and AQ is Anthraquinone. In particular embodiments, the delignified wood is compressed at a pressure of between 0.5 MPa and 10 MPa. In particular embodiments, the delignified wood is compressed at a temperature of between about 100° F. and about 250° F. In some embodiments, the densified wood is made by viscoelastic thermal compression of natural wood.

As used herein, “natural wood” refers to the composite of cellulose nanofibers embedded in a cross-linked matrix of lignin and hemicellulose as found in nature and produced by plants. Natural wood for use in the delignification and densification processes described herein can be any type of softwood or hardwood including but not limited to, basswood, oak, poplar, ash, alder, aspen, balsa wood, beech, birch, cherry, butternut, chestnut, cocobolo, elm, hickory, maple, oak, padauk, plum, walnut, willow, yellow poplar, bald cypress, cedar, cypress, Douglas fir, fir, hemlock, larch, pine, redwood, spruce, tamarack, juniper and yew.

As used herein, “delignified wood” refers to wood in which at least a portion of, or substantially all of, the lignin has been removed. In some embodiments, delignified wood is wood in which at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90% of the lignin has been removed. In some embodiments, the densified wood is made of delignified wood in which at least 30% of the lignin has been removed. In some embodiments, the densified wood is made of delignified wood in which at least 40% of the lignin has been removed. The percent lignin removed is measured relative to the lignin content in the natural wood prior to any chemical delignification process.

Removal of “substantially all of the lignin” refers to removal of at least 90% of the lignin from the natural wood. In some embodiments, at least 90%, at least 95%, at least 98%, or at least 99% of the lignin has been removed from the natural wood to form the delignified wood. As used herein, “substantially free of lignin” refers to a wood product in which at least 98% of the lignin has been removed relative to natural wood. In some embodiments, the delignified wood also has reduced hemicellulose content. In some embodiments, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% of the hemicellulose has been removed from the natural wood during the formation of delignified wood. As used herein, “substantially free of hemicellulose” refers to a wood product in which at least 98% of the hemicellulose has been removed relative to natural wood.

Without wishing to be bound by any particular theory or methodology, removal of the lignin and hemicellulose components of the natural wood results in a delignified wood that is more porous and less rigid than the natural wood due to its unique composition of mostly cellulose nanofibrils with open lumen. Compression of the delignified wood forms hydrogen bonds between the remaining cellulose nanofibers and thus improves mechanical characteristics of the densified wood. Following delignification to form delignified wood, densified wood is formed by pressing the delignified wood to compact the cells of the delignified wood. The delignified wood is pressed at a pressure of between about 0.5 MPa and about 10 Mpa. In some embodiments, the delignified wood is heated at a temperature of between about 100° F. and about 250° F. while being pressed. In some embodiments, the delignified wood is heated at a temperature of between about 150° F. and about 220° F. while being pressed.

In some embodiments, the thickness along the axis of compression of the densified wood is reduced by at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% as compared to the thickness of the natural wood across the same axis prior to delignification and densification. In some embodiments, viscoelastic thermal compression (VTC) is used to densify natural wood without delignification. Methods for VTC processing of natural wood to form densified wood are known and described in the art. See for example Kutner et al. (“The mechanical properties of densified VTC wood relevant for structural composites,” Holz als Roh- und Werkstoff, Volume 66, pages 439-446, 2008), U.S. Pat. No. 7,404,422, and U.S. Pat. No. 5,415,943, each of which is incorporated here by reference in its entirety. During compression of the delignified wood or during VTC of natural wood, the wood may be shaped into a desired form.

In some embodiments, the delignified wood is pretreated prior to, or is treated concurrently with, pressing or VTC processing. The treatment of the delignified wood, natural wood, or the densified wood may impart additional beneficial properties such as increased hydrophobicity, weather resistance, corrosion resistance (e.g., salt-water resistance), and flame resistance. In some embodiments, the delignified or densified wood may be pretreated or treated with a chemical to provide improved hydrophobic properties including, but not limited to, epoxy resin, silicone oil, polyurethane, paraffin emulsion, acetic anhydride, octadecyltrichloro silane (OTS), 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, fluoroesin, polydimethylsiloxane (PDMS), methacryloxymethyltrimethyl-silane (MSi), polyhedral oligomeric silsesquioxane (POSS), potassium methyl siliconate (PMS), dodecyl(trimethoxy) silane (DTMS), hexamethyldisiloxane, dimethyl diethoxy silane, tetraethoxysilane, methyltrichlorosilane, ethyltrimethoxysilane, methyl triethoxysilane, rimethylchlorosilane, phenyltrimethoxysilane, phenyltriethoxysilane, propyltrimethoxysilane, polymethyl methacrylate, polydiallyldimethylammonium chloride (polyDADMAC), 3-(trimethoxysilyl)propyl methacrylate (MPS, hydrophobic stearic acid, amphiphilic fluorinated triblock azide copolymers, polyvinylidene fluoride and fluorinated silane, n-dodecyltrimethoxysilane, and sodium lauryl sulfate.

In some embodiments, the delignified or densified wood may be pretreated or treated with a chemical to improve weatherability and corrosion resistance including, but not limited to cupramate (CDDC), ammoniacal copper quaternary (ACQ), chromated copper arsenate (CCA), ammoniacal copper zinc arsenate (ACZA), copper naphthenate, acid copper chromate, copper citrate, copper azole, copper 8-hydroxyquinolinate, pentachlorophenol, zinc naphthenate, copper naphthenate, kreosote, titanium dioxide, propiconazole, tebuconazole, cyproconazole, boric acid, borax, organic iodide (IPBC), and Na2B80i3 4H2O. In some embodiments, the delignified or densified wood may be pretreated or treated with a chemical to provide a particular color, shading, or tint such as, but not limited to, a paint, a stain, or a varnish.

With reference to FIGS. 1 and 2, one particular embodiment of a pouch 100 is illustrated, which includes a closure system 102 in the form of an origami over center hinge that defines a first sealing structure 104. While it is contemplated that the closure systems disclosed herein may be applied to any of a bag, a pouch, or a container, for ease of reference only the pouch 100 is discussed hereinafter. Further, any of the closure systems of the embodiments discussed herein may be applied to or made integrally with the pouch 100 shown in FIGS. 1 and 2. In some embodiments, the pouch 100 may or may not include a closure system having one or more closure elements 106. In some embodiments, a repulpable and/or recyclable pouch includes the following elements: a repulpable front wall 108 and a repulpable back wall 110, each of which defines a first side 112 (i.e., left edge), a second side 114 (i.e., right edge), a top 116, and a bottom 118.

The front wall 108 and the back wall 110 are joined together at the respective first sides 112, second sides 114, and bottoms 118. Each of the respective joinders can be a fold (if the front and back walls are continuous), or a heat seal, or any suitable joint that is essentially permanent and cannot be opened and re-closed. A re-closeable mouth 120 is defined by the top 116 of the front wall 108 and the top 116 of the back wall 110. In some embodiments, the pouch 100 may be a zippered pouch, a slider pouch, a drawstring pouch, or any other type of pouch that is unsealable, sealable, and/or resealable. Further, pouches may broadly encompass any type of component made from a repulpable and/or recyclable material for use by a consumer or industrial user. Various embodiments of pouches and closure systems are depicted herein; however, one of ordinary skill will understand that the presently disclosed system and method may encompass other containers and pouches as noted herein, and that various embodiments may be combined with other embodiments to achieve an optimal or desired solution.

Still referring to FIGS. 1 and 2, the re-closable pouch 100 is shown to include a body made up of the front wall 108 and the back wall 110, which are joined together at the respective first side 112, second side 114, and bottom 118, and the closure system 102, as disclosed herein. The pouch 100 in pouch form may be entirely made of one or more repulpable and/or recyclable materials, as described above. When the pouch 100 as a pouch is formed as a unitary component, leak paths along edges of the pouch 100, e.g., the left edge 112, the right edge 114, and the bottom edge 118, are minimized or eliminated since no additional sealing is required along the various edges or sides of the pouch 100, in contrast to some prior art pouches.

The respective tops 116 of the front wall 108 and back wall 110, define the mouth 120, which can be opened and closed using a repulpable sealing structure 104, which may be a zipper that is defined by interlocking elements that are connected to and/or adjacent to the tops 116 of the respective front and back walls. As shown in FIG. 3 for example, the repulpable zipper 124 includes at least one (or more than one) first interlocking element 126 connected to the front wall 108 and at least one (or more than one) second interlocking element 128 connected to the back wall (not shown) of the repulpable, re-closeable flexible pouch 100. In such an embodiment, the repulpable zipper 124 is movable between a first open position that disengages each of the first interlocking elements 126 from each of the second interlocking elements 128 and a second closed position that engages each of the first interlocking elements 126 to each of the respective second interlocking elements 128.

Referring again to FIG. 2, a schematic view is shown of the pouch of FIG. 1 with the first sealing structure 104 shown in a closed configuration. In the present embodiment, the first sealing structure 104 includes a first flap 130 (see FIG. 1) that is configured to be folded over a fold line 132 (see FIG. 1) to achieve the folded configuration shown in FIG. 2. Additional features, such as an adhesive (not shown) may be applied to the first flap 130, which may aid in retaining the first flap 130 to the body of the pouch 100. In some embodiments, multiple flaps may be provided, which may further aid in sealing the pouch 100 to achieve the sealed configuration shown in FIG. 2 to enclose an interior volume thereof. In some embodiments, the pouch 100 is leakproof, and in other embodiments, the pouch 100 is not leakproof. In some embodiments, adhesives and cohesives used for in the sealing structure may be selected from mucilage adhesives, cement adhesives (i.e., contact cement and rubber-based adhesives, including both natural and synthetic rubber), biopolymer-based adhesives (i.e., itaconic acid), soy protein adhesives, casein adhesives, hot melt adhesives (i.e., thermoplastic adhesives that are applied using heat), pressure sensitive adhesives (i.e., adhesives that are bonded using pressure), thermoset adhesives, glycoprotein adhesives, multipart adhesives, UV curing adhesives, cyanoacrylate adhesives (i.e., super glue), synthetic adhesives (i.e., PVA, PVAc, VAE, etc.), and combinations thereof. In some embodiments, non-polymer coatings used on the sealing structure may be selected from protein-and lipid-based biopolymers, steric acid-based coatings, PLGA (i.e., copolymers of varying ratios of polylactic acid and polyglycolic acid), polyhydroxylalkanoates, polybutylene succinate, cellulose-based biopolymers, starch-based biopolymers, and combinations thereof.

Referring now to FIG. 3, a side cross-sectional view is shown of a second sealing structure 134 including a first or male portion 136 and a second or female portion 138 shown in an open configuration. The male portion 136 includes a stem 140 from which a head 142 extends, the head 142 defining a generally triangular configuration. The female portion 138 comprises a base portion 144, an upper arm 146, and a lower arm 148 that are spaced apart from one another and extend toward one another from the base portion 144. The female portion 138 further defines a cavity 150, with rounded inner fillets 152 and a bulbous innermost area 154 which is configured to receive the male portion 136. The female portion 138 is symmetric about a longitudinal center plane or centerline 156; however, alternative a-symmetric embodiments are contemplated. The upper arm 146 and the lower arm 148 are integral with the base 144 and extend therefrom. The upper arm 146 and the lower arm 148 define an opening into the cavity 150, into which the head 142 of the male portion 136 is inserted to seal the pouch 100. The opening of the cavity 150 is defined between distal ends of the upper arm 146 and the lower arm 148. The upper arm 146 and the lower arm 148 can deflect inward or outward when the head 142 of the male portion 136 is inserted into or removed from the cavity 150.

Still referring to FIG. 3, the female portion 138 further defines a height 158 and a thickness 160, the cavity 150 defines a height 162 and a thickness 164, and the opening of the cavity 150 defines a height 166. The base portion 144 includes an inner portion 168 and an outer portion 170. The inner portion 168 is defined by a vertical line or plane that extends perpendicularly through the longitudinal centerline 172 and through an innermost point 174 along the surface defining the cavity 150. As such, the inner portion 168 includes the entire cavity 150, while the outer portion 170 does not include any portion of the cavity 150. The inner portion 168 further defines a thickness 176, which is measured in a direction parallel with respect to the centerline 172, and the outer portion 170 defines a thickness 178 measured in a direction parallel with respect to the centerline 172.

The male portion 136 of the second closure system 134 is also shown in FIG. 3, which includes the stem portion 140 that extends outward from a base portion 180 and joins the head 142. The head 142 defines an outer corner 182 and inner rounds 184 that are disposed in a triangular configuration. The head portion 142 and the stem 140 are unitary components with the male base portion 180. The base portion 180 of the male portion 136 defines a height 186 and a thickness 188, and the male portion 136 defines a thickness 190. The cavity 150 of the female portion 138 is defined by an inner surface 192. The male profile 136 is defined by an outer surface 194 that corresponds to its profile. As shown in FIG. 3, the outer surface 194 of the male portion 136 does not follow a profile of the inner surface 192 of the female portion 138. In the present embodiments, surfaces that do not follow a corresponding profile portion can be considered to have different shapes or curvatures defining the respective surfaces, i.e., they do not mirror one another or have profiles that substantially conform with one another. Non-identical profiles may be selected to provide performance benefits, such as improved vacuum sealing. In other embodiments, the surfaces may follow a corresponding profile portion having identical or substantially conforming profiles. In some embodiments, the male portion 136 and the female portion 138 combine to define a sealing structure that is a zipper that may have a polymer component, and which is coupled with the pouch 100 or made as an integral component thereof. In some embodiments, the male portion 136 and the female portion 138 are positioned at the top of the front wall 108 and the top of the back wall 110. The second sealing structure 134 is movable between a first open position that disengages the male portion 136 from the female portion 138, and a closed position.

In some embodiments, the sealing structures disclosed herein include between about 1% and about 99% by weight, or between about 3% and about 97% by weight, or between about 6% and about 94% by weight, or between about 9% and about 91% by weight, or between about 12% and about 88% by weight, or between about 15% and about 85% by weight, or between about 20% and about 80% by weight, or between about 25% and about 75% by weight, or between about 30% and about 70% by weight of a polymer and between about 1% and about 99% by weight, or between about 3% and about 97% by weight, or between about 6% and about 94% by weight, or between about 9% and about 91% by weight, or between about 12% and about 88% by weight, or between about 15% and about 85% by weight, or between about 20% and about 80% by weight, or between about 25% and about 75% by weight, or between about 30% and about 70% by weight of a repulpable material comprising plant-based cellulose.

In some embodiments, the pouch 100 disclosed herein includes between about 1% and about 99% by weight, or between about 3% and about 97% by weight, or between about 6% and about 94% by weight, or between about 9% and about 91% by weight, or between about 12% and about 88% by weight, or between about 15% and about 85% by weight, or between about 20% and about 80% by weight, or between about 25% and about 75% by weight, or between about 30% and about 70% by weight of a polymer and between about 1% and about 99% by weight, or between about 3% and about 97% by weight, or between about 6% and about 94% by weight, or between about 9% and about 91% by weight, or between about 12% and about 88% by weight, or between about 15% and about 85% by weight, or between about 20% and about 80% by weight, or between about 25% and about 75% by weight, or between about 30% and about 70% by weight of a repulpable material comprising plant-based cellulose.

In some embodiments, the densified wood pouch or sealing structure may be incorporated into a portion of, or may form the entirety of, the pouch 100 and/or the sealing structure 134. The pouch, sealing structure, and various embodiments for use with the densified wood pouches or sealing structures or portions described herein are shown in FIGS. 1-3. The embodiments shown in FIGS. 1-3 are not intended to limit the scope of the disclosure and a skilled artisan will recognize that densified wood pouches or sealing structures can be used or made in numerous manners as described herein.

As shown in FIG. 4, the sealing structure may be produced by a three-step methodology. Step 1 involves heating a mixture composed of regular paper and polymer. Step 2 includes extruding the heated mixture to produce a portion of the sealing structure, such as a male or female zipper component. Step 3 involves allowing the extruded portion to cool, thereby solidifying the structure. During Step 1, the heating process causes the remaining lignin present in the paper to reach its melting point. In some embodiments, the heating in Step 1 is conducted at a temperature of at least 284° F. (140° C.), and preferably around 320° F. (160° C.), to ensure the lignin melts and flows sufficiently to perform its binding role. Once melted, the lignin begins to flow and distribute within the fiber-oil blend. In Step 2, as the remaining molten lignin is pressurized through a mold or extruder, it mixes with the fibers in the blend, effectively reinforcing the structure. In Step 3, upon cooling, the lignin solidifies, functioning as a natural binder without the need for additional adhesives. This binding action strengthens the extrudate, enabling it to endure the mechanical pressures required for bag or pouch closures.

It is intended that the thin-thin-thin cross-hatching disclosed herein is inclusive of the materials disclosed herein, such as paper, repulpable materials, lignin, plant-based cellulose materials, polymers, binders, etc.

Additionally, as would be appreciated by those of ordinary skill in the pertinent art, the subject technology is applicable to any type of bag, pouch, package, and various other storage containers, e.g., snack, sandwich, quart, and gallon size pouches. The subject technology is also adaptable to bags having double zippers, or multiple zippers, or other types of closure mechanisms.

INDUSTRIAL APPLICABILITY

Numerous modifications will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention. The exclusive rights to all modifications which come within the scope of the application are reserved. All patents and publications are incorporated by reference herein in their entirety.