Packaging materials containing cellulose foam

Abstract

The present invention is 10 to 80 kg / m 3 and a substrate adhered to at least one outer surface of the cellulose foam.

Description

[Technical Field]

[0001] The present invention relates to packaging materials comprising cellulose foam, as well as methods for making packaging materials comprising cellulose foam. [Background technology]

[0002] Various porous materials, such as foams, are commonly used as insulation in buildings and vehicles, and as packaging materials used to protect various items during storage and transport.

[0003] Depending on the item being protected, various types of protective packaging materials can be used. Many items use lightweight cushioning materials to reduce shock and vibration. Common examples of such cushioning materials include polyurethane, polyethylene, and petroleum-based polymer foams such as Styrofoam. The foams used need to be lightweight, stable, and easy to manufacture.

[0004] There is growing interest in replacing petroleum-based polymers with polymers derived from renewable resources, i.e., bio-based polymers. Cellulose is the most abundant renewable natural polymer on Earth and is therefore of particular interest. Depending on the foam's composition, cellulosic foams may allow for the material to be recycled in conventional recycling streams.

[0005] There are several examples of cellulose foams, each prepared using a different method. Drying the wet foam composition is often a critical step. Because wet foams typically have low stability, molds are commonly used to prevent the foam from collapsing during drying. WO 20200011587 describes a porous material prepared by aerating a paste containing cellulose fibers and gluten, placing the aerated paste in a mold, and drying the paste. The dried porous material has the shape of the mold. WO 2015036659 describes a molded fiber product prepared by foaming an aqueous suspension combining natural and synthetic fibers and surfactants, feeding the fibrous foam into a mold, first mechanically extracting a portion of the water, and then drying the foam by evaporating the water to obtain a dry fiber product.

[0006] To allow for more versatile and efficient processing, foams that are already dimensionally stable in the wet state are needed.

[0007] If foams derived from petroleum-based polymers are to be replaced by, for example, cellulosic foams, many challenges related to the manufacturing process must be overcome.

[0008] For commercial foams made from petroleum-based polymers, automated foam manufacturing and packaging lines primarily use two means for product lifting and movement: pins and vacuum suction. Pin suction involves a movable arm with multiple metal pins that can be inserted into the foam at an angle, allowing the machine to lift the foam. The pin process creates small holes in the product, the size of which depends on the pin's gauge thickness. The pins must be thick enough to avoid breaking and leaving metal residue in the product. Another common lifting method is vacuum suction, which involves pressing a suction cup against the foam's surface to remove air. This process relies heavily on having a surface with low air permeability to generate vacuum suction and sufficient lift. Furthermore, certain conversion equipment, such as plotting tables, relies on vacuum suction from below to hold the sample in place during cutting. In these applications, it is crucial to prevent the sample from moving, as this could damage the vibrating blade, thereby reducing the design quality and resulting in material waste.

[0009] Because cellulose foam is generally highly breathable due to the porous structure of the foam, it is not possible to use vacuum lifting or fixing devices during manufacturing and converting operations.

[0010] One of the most common conversion techniques for packaging materials, including foams made from petroleum-based polymers, is die-cutting, in which blades arranged in a pattern are pressed against the foam to cut out specific shapes. The blades can be attached to plates in a conventional press or to rolls in a continuous production line. With regard to cellulosic foams, the foam's load-bearing and resilience properties are typically insufficient to make it a die-cutting option. Also, for other applications, such as heavy-duty packaging, the stiffness and strength of cellulosic foams may be too low to make the foam a practical option.

[0011] Another drawback of packaging materials containing cellulose foam is that the surface properties of the foam are less smooth than those of traditional papermaking, which applies pressure to the material to create a very smooth surface. The surface texture of cellulose foam is achieved by the self-compacting fibers during drying. Furthermore, the low density and porous nature of cellulose foam makes it susceptible to moisture penetration by capillary action, leading to ink bleeding during printing and resulting in poor print quality. Finally, due to its fibrous and porous nature, cellulose foam is highly hygroscopic, which can make it difficult to handle moisture condensation when used in thermal packaging of frozen foods.

[0012] Therefore, there remains a need for packaging materials that include bio-based foams that are recyclable and that also allow for the use of automated processes, including vacuum lift and fixturing equipment. To facilitate efficient foam production, particularly drying, it is desirable for the foam to be dimensionally stable even in the wet state.

[0013] Additionally, it is also desirable to be able to tailor the surface properties of packaging materials that include bio-based foams, such as surface gloss, smoothness, ink absorbency, hydrophobicity, and scratch resistance.

[0014] Furthermore, it is desirable to improve the strength and rigidity of packaging materials that include bio-based foams without compromising cushioning effectiveness. Summary of the Invention

[0015] It is an object of the present invention to provide an improved cellulose foam-containing packaging material which is recyclable and produced from renewable resources and which eliminates or mitigates at least some of the disadvantages of prior art materials.

[0016] It is a further object of the present invention to provide a packaging material comprising cellulose foam that can be used in processes involving vacuum lift and fastener devices.

[0017] It is a further object of the present invention to provide a packaging material comprising a cellulose foam that allows for customized surface properties and sufficient strength and rigidity properties depending on the application of the packaging material.

[0018] It is a further object of the present invention to provide a cellulose foam material that can be produced by drying a wet foam without the use of a mold, allowing for versatile manufacturing methods.

[0019] The above objectives, as well as other objectives which will be realized by those skilled in the art in light of this disclosure, are achieved by various aspects of the present disclosure.

[0020] According to a first aspect, the present invention provides a method for manufacturing a hose having a flow rate of 10 to 80 kg / m 3 and a substrate, wherein the substrate is attached to at least one outer surface of the cellulose foam.

[0021] Surprisingly, it has been discovered that adhering a substrate to at least one surface of a cellulose foam reduces the breathability of the cellulose foam, allowing it to be processed using a vacuum lift and fixation device. This facilitates the processing of the foam, particularly the operations used when repurposing the foam for different packaging applications. The type of substrate can be further selected to impart other desired properties to the cellulose foam, such as surface smoothness, ink absorption, hydrophobicity, surface gloss, improved scratch resistance, and improved strength and rigidity. Thus, the properties of the cellulose foam can be tailored by adhering the foam to a substrate depending on the end use of the foam. The substrate can preferably be a paper or paperboard substrate.

[0022] The cellulose foam preferably comprises 71 to 95 wt. % cellulose fiber, based on the total weight of solids in the foam, 4 to 24 wt. % water-soluble thickener, based on the total weight of solids in the foam, and at least two surfactants. Wet foams having such a composition are self-supporting and do not require a mold or other forming means to retain their shape during drying.

[0023] According to a second aspect, the present invention provides a method for manufacturing a hose having a flow rate of 10 to 80 kg / m 3 and a method for producing a packaging material comprising a cellulose foam having a density in the range of: a) providing a cellulose foam; b) providing a substrate having a first surface; c) adhering a first surface of the substrate to at least one outer surface of the cellulose foam to obtain a packaging material; d) Optionally drying the packaging material Includes:

[0024] The packaging material according to the first aspect may be produced by the method according to the second aspect. DETAILED DESCRIPTION OF THE INVENTION

[0025] As used herein, the term "foam" refers to a material produced by trapping air or gas bubbles within a solid or liquid. Typically, the volume of gas is much greater than the volume of the liquid or solid, with a thin membrane separating the gas pockets. For a foam to form, three requirements must be met. Mechanical work is required to increase the surface area. This can be done by agitation, dispersing a large amount of gas into the liquid, or injecting gas into the liquid. The second requirement is that a foaming agent (usually an amphiphile, surfactant, or surface-active component) must be present to reduce the surface tension. Finally, the foam must form faster than it can break down.

[0026] As used herein, the term "cellulose foam" refers to a foam containing cellulose and other components such as thickeners, surfactants, and additives. The main component of cellulose foam is cellulose, which accounts for at least 70% by weight of the dry weight of the cellulose foam. Cellulose is in the form of fibers, and therefore the foam can also be defined as a fibrous foam or a cellulose fiber foam. The cellulose foam can be in a wet or solid state.

[0027] As used herein, the terms "wet foam" or "wet cellulose foam" refer to a wet foam comprising cellulose and other components such as thickeners, surfactants, and additives. Air bubbles are present within the wet foam. The wet foam is self-supporting and behaves as a viscoelastic solid, meaning that it possesses both viscous and elastic properties. The wet foam behaves as a solid and is self-supporting unless sufficient force is applied to it, causing it to begin to flow and behave as a viscous material. Depending on the magnitude and time scale of the applied shear stress, the wet foam may exhibit primarily viscous or elastic behavior.

[0028] As used herein, the terms "solid cellulose foam" or "dried cellulose foam" refer to a dry porous cellulose material, i.e., a foam-forming material, formed from wet cellulose foam. During the drying process, the closed wet cellulose foam is converted into an open solid cellulose foam. The cellulose fiber network is prevented from collapsing during drying. As a result, the solid cellulose foam will have a shape that generally matches the shape of the wet cellulose foam. The dry content of the solid cellulose foam is at least 95% by weight, calculated based on the total weight of the solid cellulose foam. The shape and density of the solid cellulose foam are maintained even in an unconfined state. Solid cellulose foam has an open-cell structure, allowing air to enter the pores within the foam. Solid cellulose foam is sometimes referred to as a porous material or a low-density material.

[0029] A first aspect of the present invention relates to a packaging material comprising a cellulose foam. The cellulose foam is dry and may have a solids content in the range of 95 to 100% by weight, preferably 98 to 100% by weight, calculated relative to the total weight of the cellulose foam. The cellulose foam is solid and has a density of 10 to 80 kg / m. 3 , preferably 10 to 60 kg / m 3 , or 20 to 50 kg / m 3 It has a density in the range of

[0030] The cellulose foam preferably comprises cellulose fibers in the range of 71 to 95 wt %, for example 75 to 95 wt %, based on the total dry weight of the cellulose foam.

[0031] Cellulose fibers suitable for use in the present invention can be derived from wood, such as softwood or hardwood, leaves, or fiber crops (including cotton, flax, and hemp). Cellulose fibers suitable for use in the present invention can also be derived from regenerated cellulose, such as rayon and lyocell. Cellulose fibers suitable for use in the present invention can contain lignin or hemicellulose or both, or the cellulose fibers can be free of lignin and hemicellulose. Preferably, the cellulose fibers are derived from wood, and more preferably, the cellulose fibers are pulp fibers obtained by a pulping process that releases fibers from the wood matrix. Pulp fibers can be separated by mechanical pulping to obtain mechanical pulps, such as thermomechanical pulp (TMP) or chemical thermomechanical pulp (CTMP), or by chemical pulping, such as kraft pulp or pulps obtained by sulfite, soda, or organosolv pulping processes. More preferably, the cellulose fibers are pulp fibers separated by a chemical pulping process. The different properties of each cellulose fiber will affect the properties of the final cellulose foam. Cellulose fibers are much longer than their width. Cellulose fibers can have an average width of 0.01 to 0.05 mm. Softwood fiber lengths can be 2.5 to 4.5 mm, while hardwood fiber lengths can be 0.7 to 1.6 mm, and eucalyptus fiber lengths are 0.7 to 1.5 mm. However, fiber lengths can vary significantly depending on the habitat and other factors. The cellulose fibers in the cellulose foams disclosed herein can have lengths of 0.1 to 65 mm, 0.1 to 10 mm, 0.5 to 65 mm, 0.5 to 10 mm, or 0.5 to 7 mm. Fiber length can provide different mechanical properties to the foam. Due to the fiber length, the fibers can intertwine with each other, resulting in fiber-to-fiber bonds and strength for the foam.The aspect ratio, i.e., the ratio of fiber length to fiber width of the cellulose fibers in the cellulose foam according to the present invention, may be at least 10, at least 25, at least 50, at least 75, or at least 100, which maintains and stabilizes the foam structure during the drying process, allowing the wet cellulose foam to dry while retaining its shape. The aspect ratio may be up to 6500, or preferably up to 2000.

[0032] Cellulose fibers can be modified to provide different properties to the final cellulose foam, for example, phosphorylated or periodate oxidized fibers can be used when making cellulose foams according to the present invention.

[0033] Preferably, the cellulose fibers are selected from wood pulps such as bleached softwood kraft pulp, hardwood pulp, chemical-thermomechanical pulp, and dissolving pulp, or a combination of one or more thereof. More preferably, the cellulose pulp fibers are derived from softwood pulp, chemical-thermomechanical pulp, or dissolving pulp. Most preferably, the cellulose pulp fibers are derived from softwood pulp, such as bleached softwood kraft pulp.

[0034] The cellulose foam preferably comprises cellulose fibers in the range of 71 to 95 wt. %, for example 75 to 95 wt. %, based on the total dry weight of the cellulose foam, a water-soluble thickener in the range of 4 to 24 wt. %, for example 5 to 20 wt. %, based on the total dry weight of the cellulose foam, and at least two surfactants.

[0035] The water-soluble thickener may have a molecular weight of 80,000 to 250,000 g / mol, or 83,000 to 197,000 g / mol. Exemplary water-soluble thickeners are selected from carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxyethyl cellulose (HEC), ethyl hydroxyethyl cellulose (EHEC), methyl hydroxypropyl cellulose (MHPC), starch, xanthan gum, guar gum, and xyloglucan, or mixtures thereof. The water-solubility of the thickener facilitates recycling of the cellulose foam.

[0036] Water-soluble thickeners can improve the bond strength between fibers in cellulose foams, mainly through hydrogen bonding. Therefore, the amount of water-soluble thickener will affect the mechanical performance of the cellulose foam, especially the bulk of the material. A higher content of water-soluble thickener provides a higher rigidity to the material. Therefore, water-soluble thickeners allow for customization of mechanical properties.

[0037] The cellulose foam may also contain a mixture of at least two surfactants. One of the at least two surfactants is preferably a fast-acting surfactant. A surfactant suitable for this purpose is an anionic surfactant, preferably a low-molecular-weight anionic surfactant. The anionic surfactant may have an apparent pKa of 3.2 to 3.8, preferably 3.4 to 3.6, or an apparent pKa of 3.5 in a solution having a pH of 7 to 9, preferably 8. The low-molecular-weight anionic surfactant may be selected from sodium dodecyl sulfate (SDS); potassium dodecyl sulfate, sodium laureth sulfate (SLES); sodium dodecylbenzenesulfonate; sodium cocoyl sarcosinate; and sodium lauroyl sarcosinate. The low-molecular-weight anionic surfactant is preferably selected from sodium dodecyl sulfate (SDS); sodium pn-dodecylbenzenesulfonate; sodium cocoyl sarcosinate; and sodium lauroyl sarcosinate. More preferably, the low-molecular-weight anionic surfactant is sodium cocoyl sarcosinate. The anionic surfactant may be biodegradable.

[0038] The other of the at least two surfactants is preferably a co-surfactant. The co-surfactant can be selected from the group consisting of surfactants having an apparent pKa of at least 8, or at least 9, in a surfactant solution having a pH of 7 to 9, preferably pH 8; and amphoteric betaines. The co-surfactant can have a maximum apparent pKa of 10. The co-surfactant preferably has a long carbon chain, more preferably a carbon chain having 14 carbon atoms (C14). The co-surfactant can be selected from high pKa fatty acids from plant-derived sources, such as tetradecanoic acid (myristic acid), sodium oleate, lauric acid, palmitic acid, and stearic acid; glucose-based co-surfactants with aliphatic carbon chains, such as alkyl glycosides, alkyl polyglucosides, alkyl thioglycosides, and alkyl maltosides; amphoteric betaines, such as cocamidopropyl betaine (CAPB) and sodium cocoiminodipropionate (CADP); polyethylene glycol sorbitan monolaurate, i.e., tween® (e.g., tween 20, tween 80, and tween 85); and polyoxyethylene lauryl ethers, such as polyethylene glycol dodecyl ether, pentaethylene glycol monododecyl ether, and octaethylene glycol monododecyl ether.

[0039] Therefore, the at least two surfactants used in the cellulose foam preferably comprise a mixture of an anionic surfactant and a co-surfactant. The molar ratio of the anionic surfactant to the co-surfactant may be 0.2:1 to 3:1, preferably 0.5:1 to 2:1. The total amount of the at least two surfactants contained in the cellulose foam may be 0.6 to 5 wt. % or 0.8 to 2.0 wt. % calculated based on the total weight of the cellulose foam.

[0040] The cellulose foam can be redispersed in water and therefore is recyclable in the normal paper recycling stream.

[0041] The cellulose foam is prepared by the following steps: - decomposing cellulose fibers in water to obtain a cellulose fiber slurry; - adding a water-soluble thickener to the slurry to obtain a mixture of thickener and cellulose fibers in water; - adding at least two surfactants to the mixture to obtain a fiber suspension; and - aerating a fiber suspension to obtain a wet foam, the wet foam comprising 10 to 38% by weight of cellulose fibers, 0.5 to 10% by weight of a water-soluble thickener, and 0.1 to 2% by weight of a surfactant, calculated relative to the total weight of the wet foam, and the foam has a viscosity of 140 to 500 kg / m 3 and a yield stress of 40 to 400 Pa; - drying the wet foam to obtain a dry cellulose foam The compound can be prepared using a method comprising:

[0042] The addition of water-soluble thickeners increases the viscosity of the slurry, allowing sufficient air to be entrapped during aeration to produce a tightly packed foam. Because the cellulose fibers are mixed at high concentrations, a drainage step is not necessary, allowing the use of high concentrations of water-soluble bio-based thickeners.

[0043] The addition of a fast-acting surfactant will contribute to the formation of a dense, high-viscosity cellulose foam, as it will settle quickly between the air-water phase during aeration. This allows for a self-supporting wet cellulose foam. The addition of a co-surfactant together with the fast-acting surfactant will further enhance the properties of the cellulose foam, as it will accelerate the action of the fast-acting surfactant. A co-surfactant with an appropriate pKa and long carbon chain will further contribute to the formation of a stable fiber suspension and a stable wet cellulose foam.

[0044] Upon aeration, a composition comprising cellulose fibers, a thickener, and at least two surfactants will form a highly stable wet fiber foam. Aeration can be achieved by mechanical agitation, incorporating a significant amount of air into the material. Foam formation can be facilitated by the surfactant. By adjusting the stability of the wet foam using a combination of a thickener and a surfactant, a free-standing cellulose foam can be produced without the use of crosslinkers or fibrillated cellulose. The good stability of the foam prevents ripening, i.e., changes in cell size, and drainage. The resulting wet foam is free-standing and does not require a mold or forming cloth to maintain its shape upon drying. The wet foam can be molded into a free-standing foam that is stable enough to dry without collapsing, even in the absence of a supporting mold. As a result, objects can be molded and dried without the use of a mold.

[0045] The cell size in the wet foam is usually less than 100 μm. This results in a homogeneous wet foam with good stability that does not agglomerate during processing. The average cell size is generally maintained during processing and the subsequent drying step, and the cellulose fibers remain well dispersed. The solid cellulose foam obtained by drying the wet foam has a homogeneous structure, is strong, has good mechanical properties, a smooth surface, and is free of defects. When a substrate is to be adhered to the foam, a smooth surface is beneficial because it can facilitate adhesion.

[0046] In contrast, less stable wet cellulose foams have larger average cell sizes (i.e., typically greater than 100 μm), which result in faster cell coalescence during processing and drying, resulting in the formation of larger cells. Additionally, cellulose fibers will form clusters during processing and drying, resulting in the collapse of the wet foam during drying. The resulting solid cellulose foam will not have a homogeneous structure and will contain defects, such as voids, resulting from the coalescence of cells in the wet foam. These defects will cause the solid cellulose foam to be brittle and have a rough surface.

[0047] Due to the high solids content, the wet foam does not need to be dehydrated before drying. The foam can be dried by evaporation at room temperature or at elevated temperatures, e.g., temperatures between 40°C and 140°C. The dry cellulose foam has a drying capacity of 10 to 80 kg / m 3 , or 10 to 60 kg / m 3 , or 20 to 50 kg / m 3 The density of the .mu.m particle may be .mu.m.

[0048] In a preferred embodiment, the cellulose foam comprises 71 to 95 wt. % of cellulose fibers, e.g., 75 to 95 wt. % of cellulose fibers, based on the total dry weight of the cellulose foam; 4 to 24 wt. % of a water-soluble thickener, based on the total dry weight of the cellulose foam, e.g., 5 to 20 wt. % of a water-soluble thickener, based on the total dry weight of the cellulose foam; and at least two surfactants. A wet cellulose foam having such a composition has a homogeneous structure and, as discussed above, good stability. Such a wet cellulose foam can also be dried without prior dehydration.

[0049] Cellulose foam can be prepared by a two-stage deposition. In the first deposition, wet foam is deposited onto a surface as individual units and at least partially dried. During drying, a dense layer forms on the outer surface of the individual units. In the second deposition, a wet foam, preferably having the same composition as the wet foam in the first deposition, is deposited to fill the space around the individual units of the first deposition. After drying, a solid cellulose foam is obtained, containing the individual foam units embedded within a foam matrix. The dense layer on the outer surface of the individual units provides mechanical support by helping the individual units maintain their shape during drying of the foam in the second deposition and the entire cellulose foam.

[0050] The cellulose foam in the packaging material according to the first embodiment can have any shape, such as a block, a cube, a cylinder, or an irregular shape. Preferably, the cellulose foam has at least one flat surface. The flat surface facilitates adhesion of the substrate. The substrate is attached to at least one outer surface of the cellulose foam. As used herein, the term "outer surface" refers to the outermost surface of the cellulose foam. It is not intended to refer to the outermost surface of the packaging material. As used herein, the term "flat" refers to a horizontal surface without recesses or protrusions.

[0051] In some embodiments, the cellulose foam can have at least one uneven surface, such as a surface having protruding portions, to which a substrate is attached.

[0052] In one embodiment, the cellulose foam is provided in the form of a slab having a thickness ranging from 1 to 20 cm, preferably from 1 to 10 cm, and more preferably from 4 to 6 cm. The length and width dimensions of the slab are typically in the range of 100 to 300 cm. The slab can be cut into smaller pieces, but preferably has the same thickness even after cutting. In an embodiment in which the cellulose foam is provided in the form of a slab, the exterior surfaces are present on the top, bottom, and sides of the slab.

[0053] The cellulose foam may have a dense layer on at least one outer surface. In embodiments in which the cellulose foam is provided in the form of a slab, the cellulose foam has a dense layer on at least the top and bottom surfaces, and optionally on the sides.

[0054] The dense layer contains cellulose fibers that are more densely packed and partially oriented differently than the bulk. The dense layer forms on the outer surface of the wet foam during drying and remains on the outer surface of the dried cellulose foam. The dense layer has improved mechanical stability and strength compared to the core of the cellulose foam. The core of the cellulose foam contains a homogeneous open-cell fiber network. The core is highly porous, while the dense layer has a denser structure than the core, but is still porous.

[0055] The dense layer provides the cellulose foam with improved stability and mechanical strength. Therefore, in embodiments in which the cellulose foam is provided in the form of a plank, it is advantageous to cut the foam plank so that the cut is made in such a way that the thickness of the plank remains the same after cutting, thus ensuring that the dense layer is still present on the top and bottom surfaces. However, in other applications, the plank can be cut so that the dense layer is not present after cutting.

[0056] The substrate may be adhered to the outer surface of the cellulose foam including the dense layer, or may be adhered to the outer surface of the cellulose foam without the dense layer.

[0057] According to a first aspect of the invention, a substrate is attached to at least one outer surface of a cellulose foam.

[0058] Any suitable substrate can be used, such as a plastic film, a metal foil, or a fibrous substrate. Preferably, the substrate is selected from paper or paperboard. The breathability of the substrate may be lower than that of cellulose foam. Therefore, the substrate can be selected to have a sufficiently low breathability depending on the application.

[0059] By adhering a substrate to a cellulose foam, the pores on the outer surface are covered by the substrate, thereby reducing the breathability of the cellulose foam. By reducing the breathability of the cellulose foam by adhering a substrate to at least one outer surface, the resulting packaging material is much easier to use in automated processes involving vacuum. The packaging material can be used, for example, in converting and packaging processes that involve steps requiring vacuum lifting and fixation. The reduced breathability also improves the performance of the packaging material in thermal packaging.

[0060] Adhering a substrate to a cellulose foam can also improve other properties of the packaging material, such as stability, rigidity, and strength. For example, when a rigid substrate is attached to a cellulose foam, pressure is distributed over a larger area, minimizing compression when applied, improving load-bearing capacity and allowing the use of die-cutting. Adhering a substrate to a cellulose foam can combine the rigidity of the substrate with the cushioning properties of the foam, allowing for packaging materials with properties that can be customized for various applications, including heavy loads. When using flaked cellulose foam, adhering a substrate to the foam makes handling much easier. The risk of tearing the flaked foam is also reduced.

[0061] The substrate preferably has a flat shape such as a sheet, film, or foil. The substrate includes at least a first surface and a second surface. The substrate includes the first surface at least partially adhered to the cellulose foam.

[0062] As used herein, the term "bonding" refers to the process of permanently attaching two objects, in this case, a cellulose foam and a substrate.

[0063] In some embodiments, the area of ​​the first surface of the substrate is the same size as the area of ​​the outer surface of the cellulose foam to which the substrate is adhered, and thus, in such embodiments, the entire first surface of the substrate is attached to the cellulose foam.

[0064] In some embodiments, the first surface area of ​​the substrate that is attached to the cellulose foam has a size that is larger or smaller than the area of ​​the outer surface of the cellulose foam to which the substrate is adhered. Thus, in such embodiments, the first surface of the substrate is partially attached to the cellulose foam.

[0065] In some embodiments, the substrate is attached to one outer surface of the cellulose foam. For example, a paperboard can be adhered to a cellulose foam plank, with a first surface of the paperboard having an area approximately the same as the outer surface of the plank.

[0066] In some embodiments, the substrate is attached to at least two outer surfaces of the cellulose foam. In such embodiments, the substrate can be folded along at least one fold line so that it can be adhered to at least two outer surfaces of the cellulose foam. For example, a paperboard can be provided with fold lines that correspond to the edges of the cellulose foam plank. By folding the paperboard along the fold lines, the cellulose foam can be adhered to the paperboard on all sides.

[0067] In some embodiments, the substrate can be a plastic film or a metal foil. The plastic film can be selected from, for example, polyethylene, cellophane, or polylactic acid. The metal foil can be, for example, aluminum foil. The plastic film and metal foil should be thin enough so that the packaging material can be recycled in the normal paper recycling stream. Adhering a plastic film or metal foil to the outer surface of a cellulose foam reduces the breathability of the cellulose foam.

[0068] In some embodiments where the substrate is a plastic film or metal foil, the plastic film and metal foil are preferably, but not necessarily, thin enough to allow the packaging material to be recycled in normal paper recycling streams.

[0069] In a preferred embodiment, the substrate is a fibrous substrate. The fibrous substrate preferably comprises cellulose fibers. The cellulose fibers can be selected from wood pulp; regenerated cellulose fibers; and plant fibers, such as fibers derived from bamboo, cotton, hemp, flax, and jute. Preferably, the cellulose fibers are selected from wood pulp, such as softwood pulp, hardwood pulp, chemical-thermomechanical pulp, and dissolving pulp, or one or more combinations thereof.

[0070] The fibrous substrate may preferably be selected from paper or paperboard, for example, the fibrous substrate may be paperboard, cardboard, or corrugated board.

[0071] As used herein, the term "paper" generally refers to a material made from wood pulp or other fibrous substances containing cellulose fibers in thin sheets or rolls and used, for example, for writing, drawing, or printing, or as a packaging material. Paper can be made either bleached or unbleached, coated or uncoated, and in a variety of thicknesses, depending on the requirements of the end use.

[0072] As used herein, the term "paperboard" generally refers to a strong, thick paperboard or cardboard comprising cellulose fibers that is used, for example, as a flat substrate, tray, box, and / or other type of packaging. Paperboard can be produced in a variety of thicknesses, either bleached or unbleached, coated or uncoated, depending on the end-use requirements.

[0073] An advantage of using paper or paperboard as a substrate is that packaging materials comprising cellulose foam bonded to paper or paperboard can be redispersed in water and, as a result, are readily recyclable in the normal paper recycling stream. Bonding a paper or paperboard substrate to the cellulose foam also reduces breathability, which can improve the stability of the foam.

[0074] The basis weight of the fibrous substrate is at least 20 g / m 2 , or at least 80 g / m 2 The basis weight of the fibrous substrate is preferably 500 g / m 2 Less than or 400g / m 2 The basis weight of the fibrous substrate is preferably 20 to 500 g / m 2 , or 80 to 500 g / m 2 , or 120 to 500 g / m 2 It can be in the range of.

[0075] The substrate can be selected to impart desired properties beyond reducing breathability and improving the strength and stability of the packaging material. For example, if the packaging material is printed in a converting process, it is advantageous to adhere a substrate that will improve printability by minimizing ink bleeding. The substrate can also be selected to alter the appearance and feel of the packaging material with respect to properties such as gloss and texture. In applications where it is important that the packaging material have improved water resistance, a hydrophobic substrate can be selected.

[0076] In some embodiments, the substrate is a second cellulose foam material. Such embodiments provide a layered cellulose foam material. The second cellulose foam may have the same composition as the cellulose foam or a different composition. The second cellulose foam may also be selected to provide certain desired properties for the packaging material, as discussed further above.

[0077] In some embodiments, the substrate is a different foamed material, such as a starch foam.

[0078] In some embodiments, a second substrate is attached to at least one outer surface of the cellulose foam. The second substrate may be the same as or different from the substrate. The substrate and the second substrate may be attached to the same outer surface of the cellulose foam or to different outer surfaces. In one preferred embodiment, the substrate and the second substrate are attached to opposing outer surfaces of the cellulose foam such that the cellulose foam is sandwiched between the substrate and the second substrate. For example, cardboard may be attached to the top and bottom surfaces of the cellulose foam.

[0079] Adhering a second substrate to the cellulose foam further improves strength and rigidity. By selecting a second substrate that is different from the substrate, packaging materials with different properties on both sides can be provided. For example, the aesthetics of the top surface of the cellulose foam can be improved while providing increased strength to the back surface of the foam.

[0080] The second substrate may be further defined as outlined above with respect to the substrate.

[0081] In some embodiments, the cellulose foam comprises at least two individual pieces of the cellulose foam, and a substrate is attached to at least one outer surface of all of the at least two individual pieces. The cellulose foam compositions of the at least two individual pieces may be the same or different. Other properties, such as density, size, and shape, of the at least two individual pieces may be the same or different. By providing at least two individual pieces of cellulose foam and adhering a substrate to at least one outer surface of each of the at least two individual pieces of cellulose foam, a highly versatile packaging material is provided. By selecting cellulose foam pieces with defined shapes and properties and adhering them to a substrate, packaging materials with customized stiffness and cushioning properties can be provided depending on the application.

[0082] In some embodiments, the packaging material includes an adhesive layer between at least one outer surface of the cellulose foam and the substrate. The substrate is attached to at least one outer surface of the cellulose foam by the adhesive layer. The adhesive layer can include any suitable adhesive, such as, for example, hot melt adhesives, wood adhesives, starch-based adhesives, carboxymethyl cellulose (CMC), polyvinyl acetate, ethylene vinyl acetate, casein, latex, polyurethane, dextrin, and gums such as guar gum and xanthan gum. The adhesive is preferably water-based and / or bio-based.

[0083] In some embodiments, the adhesive layer is a double-sided adhesive tape.

[0084] In embodiments in which the cellulose foam contains CMC, the adhesive layer may contain water. The water will partially dissolve the outer surface of the cellulose foam, exposing the CMC and providing adhesive properties. A substrate may be adhered to the partially dissolved outer surface.

[0085] In some embodiments, the adhesive layer can include a thin layer of wet cellulose foam. The use of a thin layer of wet foam as the adhesive layer is particularly suitable when the substrate is a second cellulose foam, thereby producing a layered material that includes only cellulose foam.

[0086] In some embodiments, the packaging material comprises at least two adhesive layers, which may be the same or different in composition.

[0087] In embodiments in which a second substrate is attached to the cellulosic foam, the second substrate may be adhered by an adhesive layer as defined above.

[0088] The packaging material may also include an additional layer. The type of material for the additional layer is not particularly limited. It may be, for example, cellulose foam, paper or paperboard, a plastic film, or a metal foil. For example, the additional layer may be adhered to the other side of the substrate. In one example, a corrugated board substrate is adhered to cellulose foam, and another cellulose foam is adhered to the opposite side of the corrugated board, so that the corrugated board is sandwiched between two layers of cellulose foam. In another example, a plastic film may be adhered to a paperboard substrate, which is then adhered to the cellulose foam.

[0089] According to a second aspect, the present invention provides a method for manufacturing a hose having a flow rate of 10 to 80 kg / m 3 , e.g., 10 to 60 kg / m 3 , or 20 to 50 kg / m 3 The present invention relates to a method for producing a packaging material comprising a cellulose foam having a density in the range of 140 to 500 kg / m. Step a) of the method according to the second aspect comprises providing a cellulose foam. The provided cellulose foam may be in a wet or dry state. When a wet cellulose foam is provided, it may be applied onto a substrate and then dried. Alternatively, a substrate may be adhered onto the wet foam before drying. The density of the wet foam is in the range of 140 to 500 kg / m. 3 The wet foam of the present invention, due to its viscoelasticity, will be self-supporting and will therefore have an outer surface to which a substrate can be adhered.

[0090] In embodiments in which the cellulose foam is provided as a solid cellulose foam, the foam may have a solids content in the range of 95 to 100 wt.%, preferably 98 to 100 wt.%, calculated on the total weight of the cellulose foam. The cellulose foam has at least one outer surface.

[0091] The cellulose foam may be further defined as described above with reference to the first embodiment.

[0092] Step b) of the method according to the second aspect comprises providing a substrate. The substrate is preferably dry. The substrate comprises a first surface and at least one second surface. Preferably, the substrate is in the form of a sheet, film, or foil. The substrate may be further defined as described above with reference to the first aspect.

[0093] Step c) of the method according to the second aspect comprises adhering a first surface of the substrate to at least one outer surface of the cellulose foam. The adhering step may comprise applying an adhesive layer to the first surface of the substrate and / or to at least one surface of the cellulose foam.

[0094] The step of adhering the first surface of the substrate to at least one outer surface of the cellulose foam includes bringing the first surface of the substrate and the at least one outer surface of the cellulose foam into intimate contact with one another. In some embodiments, an adhesive layer is disposed between the outer surface of the cellulose foam and the first surface of the substrate.

[0095] In some embodiments, pressure is applied when the first surface of the substrate is attached to at least one outer surface of the cellulose foam. Applying pressure during the bonding step ensures that the substrate and the cellulose foam adhere to each other and form a strong bond. Pressure can be applied using any suitable pressure means. For example, a roller, a bar, or a plate can be used. Pressure can be applied to the substrate, the cellulose foam, or both. For example, after placing the substrate on the cellulose foam, the structure can be passed under a roller to apply pressure and firmly bond the substrate to the cellulose foam.

[0096] The bonding step typically involves manually or automatically placing the cellulose foam on the substrate, or vice versa. Any suitable device known to those skilled in the art can be used. For example, an adhesive layer is first applied to the outer surface (typically the top surface) of the cellulose foam, and then cardboard is placed on the outer surface. The cardboard can be fed from a roller, which can apply pressure as the cardboard is placed on the cellulose foam to ensure a strong bond. Alternatively, pressure can be applied by a second roller.

[0097] Depending on the substrate and bonding means, elevated temperatures may also be used during the bonding step. For example, in embodiments where the substrate is a plastic film, the plastic film and / or the cellulose foam may be heated during the bonding step to laminate the plastic film to the cellulose foam. Heat may also be required for certain adhesives. In embodiments where pressure is applied during the bonding step, heat may be supplied by a pressure means, such as using a heated roller.

[0098] The adhesive layer can be applied to the first surface of the substrate and / or the outer surface of the cellulose foam using any suitable coating method, such as roller coating, blade / knife coating, brushing, flexographic roller, and spray coating. In some embodiments, the adhesive layer is applied to the first surface of the substrate before adhering the substrate to the cellulose foam. In some embodiments, the adhesive layer is applied to the outer surface of the cellulose foam before adhering the substrate to the cellulose foam. In some embodiments, the adhesive layer is applied to both the first surface of the substrate and at least one outer surface of the cellulose foam before adhering the substrate to the cellulose foam. Applying an adhesive layer to both the substrate and the cellulose foam can result in a stronger and more durable bond.

[0099] In some embodiments, the method includes the additional step of providing a second substrate and adhering the substrate to at least one outer surface of the cellulose foam. A first surface of the substrate is attached to at least one outer surface of the cellulose foam. The second substrate is preferably attached by applying an adhesive layer to the first surface of the second substrate and / or at least one outer surface of the cellulose foam. The second substrate may be further defined as described above with reference to the first aspect.

[0100] In embodiments that include a second substrate, the second substrate may be adhered to the cellulose foam simultaneously with the substrate or after the substrate is adhered to the cellulose foam. Adhesion of the second substrate may include an adhesive layer, pressure, and / or elevated temperature, as further outlined above in connection with adhering the substrates.

[0101] The adhesive layer may comprise multiple adhesive sub-layers, such as at least two adhesive sub-layers, or at least three adhesive sub-layers. The adhesive compositions of the at least two sub-layers may be the same or different. The adhesives and adhesive layers may be further defined as described above with reference to the first aspect.

[0102] Step d) of the method according to the second aspect comprises the optional step of drying the packaging material. The packaging material can be dried by evaporation at room temperature or at an elevated temperature, for example at a temperature of 40 to 140° C. Any suitable drying device can be used, such as an oven or infrared heating.

[0103] In embodiments where the provided cellulose foam is a wet cellulose foam, drying is required to obtain the packaging material. In embodiments that include an adhesive layer, drying may be beneficial. [Example]

[0104] Example 1 - Preparation of cellulose foam A uniform wet paste containing cellulose pulp fibers (softwood kraft bleached pulp), a thickener (CMC), and water was prepared. The solids concentration of the wet paste was 13.2% by weight. After adding a surfactant (a mixture of myristic acid and sodium cocoyl sarcosinate) to the paste, it was aerated by mechanical mixing until a wet foam with a density of 226 kg / m 3 was obtained. The composition of the wet foam is shown in Table 1. Next, the wet foam was used to fill a wooden frame. After the wooden frame was completely filled with the wet foam, the excess foam was scraped off to obtain a smooth surface. The foam was dried in an oven at 120 °C until completely dry. The dried cellulose foam had a density of 30 kg / m 3 . The foam had a flat shape with a thickness of 5 cm. TIFF2025533759000001.tif29170

[0105] Example 2 - Preparation of packaging material A packaging material was prepared using the cellulose foam board of Example 1. An adhesive layer containing a CMC solution (10% by weight in water) was coated on the upper and lower surfaces of the foam board. The adhesive layer was applied with an amount of dry material of 20 g / m 2 . A single layer of recycled cardboard was adhered to the upper and lower surfaces of the foam board to obtain a packaging material in which the cellulose foam board was sandwiched between two layers of cardboard. The size of the cardboard was the same as that of the foam board. By adhering the cardboard to the foam, the mechanical properties of the foam were improved. The cardboard had a thickness of 2.5 mm, and the basis weight of the cardboard was 70 g / m 2 , and the basis weight of the kraft liner was 50 g / m 2 .

[0106] Considering the above detailed description of the present invention, other modifications and variations will be apparent to those skilled in the art. However, it will be apparent that such other modifications and variations are possible without departing from the spirit and scope of the present invention.

Claims

1. 10-80 kg / m ３ A packaging material comprising a cellulose foam having a density in the range and a substrate, wherein the substrate is attached to at least one outer surface of the cellulose foam.

2. The packaging material according to claim 1, wherein the cellulose foam contains cellulose fibers in the range of 71 to 95% by weight, based on the total dry weight of the cellulose foam.

3. The packaging material according to claim 1, wherein the cellulose foam comprises cellulose fibers in the range of 71 to 95% by weight based on the total dry weight of the cellulose foam, a water-soluble thickener in the range of 4 to 24% by weight based on the total dry weight of the cellulose foam, and at least two surfactants.

4. The packaging material according to claim 1, wherein the base material is a fibrous base material.

5. The packaging material according to claim 1, wherein the base material is selected from paper or cardboard.

6. The packaging material according to claim 1, wherein the base material is a second cellulose foam, and the second cellulose foam may have the same composition as the cellulose foam or a different composition.

7. The packaging material according to claim 1, wherein the cellulose foam comprises at least two separate pieces of the cellulose foam, and the substrate is attached to at least one outer surface of all of the at least two separate pieces.

8. The packaging material according to claim 1, wherein the packaging material includes an adhesive layer between at least one outer surface of the cellulose foam and the substrate.

9. The packaging material according to claim 1, wherein the second substrate is attached to at least one outer surface of a cellulose-based foam.

10. 10-80 kg / m ３ A method for producing a packaging material comprising a cellulose foam having a density in the range of, the following: a) the step of providing a cellulose foam; b) the step of providing a substrate having a first surface; c) To obtain a package material, the first surface of the substrate is attached to at least one outer surface of the cellulose foam; d) A step of optionally drying the packaging material Methods that include...

11. Cellulose foam, 140-500 kg / m³ ３ The method according to claim 10, provided as a wet foam having a density in the range of .

12. Cellulose foam, 10-80 kg / m³ ３ The method according to claim 10, provided as a solid cellulose foam having a density in the range of .

13. The method according to claim 10, wherein the cellulose foam contains cellulose fibers in the range of 71 to 95% by weight, based on the total dry weight of the cellulose foam.

14. The method according to claim 10, wherein the cellulose foam comprises cellulose fibers in the range of 71 to 95% by weight based on the total dry weight of the cellulose foam, a water-soluble thickener in the range of 4 to 24% by weight based on the total dry weight of the cellulose foam, and at least two surfactants.

15. The method according to claim 10, wherein the base material is a fibrous base material.

16. The method according to claim 10, wherein the base material is selected from paper or cardboard.

17. The method according to claim 10, wherein the base material is a second cellulose foam, and the second cellulose foam may have the same composition as the cellulose foam or a different composition.

18. The method according to claim 10, wherein the cellulose foam is provided as at least two separate pieces of the cellulose foam, and a substrate is attached to at least one outer surface of all of the at least two separate pieces.

19. The method according to claim 10, wherein the step of attaching a substrate to at least one surface of a cellulose foam comprises applying an adhesive layer to a first surface of the substrate and / or to at least one surface of the cellulose foam.

20. The method according to claim 10, wherein the method comprises the steps of providing an additional, second substrate and attaching the second substrate to at least one outer surface of a cellulose foam.