Multilayer product and its manufacturing method

Abstract

A multi-layer product is disclosed. The multi-layer product may include a base layer based on cellulose fibers and a barrier layer. The barrier layer may include at least 10% (w / w) hydrolyzed cellulose fibers. The multi-layer product may further include a cellulose film layer.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to multi-layer products and methods for making the same. [Background technology]

[0002] The demand for packaging materials is increasing significantly. There is a need for packaging means that are renewable, recyclable and biodegradable.

[0003] Cellulose, for example in the form of cellulose fibers or pulp, is a renewable and biodegradable material well suited for packaging. However, in many cases, plastic materials or other less environmentally friendly materials may be required, for example as coatings to impart barrier properties to packaging materials formed primarily from cellulose. Such packaging materials are not completely biodegradable, and their recycling may be complicated. Summary of the Invention [Means for solving the problem]

[0004] A multi-layer product is disclosed. The multi-layer product may include a base layer based on cellulose fibers and a barrier layer. The barrier layer may include at least 10% (w / w) hydrolyzed cellulose fibers. The multi-layer product may further include a cellulose film layer. [Brief explanation of the drawings]

[0005] The accompanying drawings, which are included to provide a further understanding of the embodiments and constitute a part of this specification, illustrate various embodiments.

[0006] [Figure 1A] An embodiment of a multi-layer product 1 is shown in cross section. [Figure 1B] 1 illustrates another embodiment of a multi-layer product. [Figure 1C] 1 illustrates another embodiment of a multi-layer product. [Figure 1D]10 illustrates yet another embodiment of a multi-layer product. [Figure 2A] The oxygen permeability of the cellulose film is shown. [Figure 2B] The grease permeability of cellulose films is shown. [Figure 3] 1 shows a packaging material produced by compression molding a fibrous body having a cellulose film layer. [Figure 4] 1 shows a packaging material produced by calendering a fibrous body having a cellulose film layer. [Figure 5A] The apparent bulk density values ​​of certain fiber blends are given. [Figure 5B] The tensile index values ​​for specific fiber blends are given. [Figure 5C] The strain at break values ​​for specific fiber blends are given. [Figure 6] 1 shows the measured air permeability of the multilayer structure. DETAILED DESCRIPTION OF THE INVENTION

[0007] A multilayer product is disclosed.

[0008] The multi-layer product may comprise a base layer based on cellulose fibers and a barrier layer. The barrier layer may comprise at least 10% (w / w) hydrolyzed cellulose fibers. The multi-layer product may further comprise a cellulose film layer.

[0009] Hydrolyzed cellulose fibers are moldable materials, and when a barrier layer material containing hydrolyzed cellulose fibers is densified, for example by compression, a layer of material with low porosity may be obtained. Hydrolyzed cellulose fibers may have surface-closing properties. For example, a highly dense structure may be obtained from the barrier layer material by calendering. Such a layer may have barrier properties. For example, such a layer may be a gas (oxygen) barrier layer and / or a grease barrier layer, such as an oil barrier layer.

[0010] The base layer may act as a support layer, ie, provide mechanical strength to the multi-layer product.

[0011] The base layer and the barrier layer may both be formed from cellulosic materials. In other words, the barrier layer may also be based on cellulose fibers. The cellulose film layer may also be formed from cellulosic materials. Thus, the entire multi-layer product may be formed from cellulosic materials, or may be formed primarily from cellulosic materials.

[0012] The compositions of the base layer and barrier layer may be selected so that the strength and, on the other hand, the density of the multi-layer product may be optimized as desired, and the composition of the barrier layer may also be selected to provide desired barrier properties.

[0013] Additionally, the properties of the multi-layer product may be tailored by including a cellulose film layer.

[0014] Such multilayer products do not necessarily require, for example, plastic coatings or other non-cellulose-based layers or coatings. For example, barrier properties have traditionally been achieved using fluorochemicals, which are, for example, harmful to the environment and whose use may be phased out in the future. Eliminating or reducing the need to use additional layers or coatings to achieve barrier properties may be very useful, for example, for environmental reasons. Multilayer products according to one or more embodiments described herein may be biodegradable and relatively easily recyclable using existing processes. For example, up to 50% of the cellulose fibers in the multilayer product may be recoverable in a recycling process. The multilayer product may also be compostable. The multilayer product may be burned and may burn relatively cleanly.

[0015] The barrier layer may at least partially cover the base layer, or the base layer may at least partially cover the barrier layer.

[0016] The barrier layer and base layer may be attached to one another directly or through one or more additional layers or media such as adhesives.

[0017] The barrier layer and the base layer may be at least partially overlapped, or the barrier layer and the base layer may be completely overlapped.

[0018] The barrier layer may or may not be the outermost layer of the multi-layer product, and depending on the embodiment, the barrier layer may be covered on both sides with other layers.

[0019] The multi-layer product may include at least two layers, such as two, three or more layers.

[0020] The multi-layer product may include at least one barrier layer.

[0021] The multi-layer product may include at least one base layer.

[0022] The multi-layer product may include at least one barrier layer and at least one base layer.

[0023] The multilayer product may further comprise additional layers. For example, the multilayer product may comprise an intermediate layer (or at least one intermediate layer) between the base layer and the barrier layer. Such an intermediate layer may also be based on cellulose fibers. However, its composition may differ from that of the base layer and / or the barrier layer. The multilayer product may comprise two or more base layers and / or two or more barrier layers.

[0024] The multi-layer product may include a base layer and two barrier layers, the barrier layers being disposed on either side of the base layer.

[0025] The multi-layer product may include a barrier layer and two base layers, the base layers being disposed on either side of the barrier layer.

[0026] The barrier layer may be densified and / or compressed, in other words, the barrier layer may be a densified and / or compressed layer.

[0027] The base layer may be densified and / or compressed, in other words, the base layer may be a densified and / or compressed layer.

[0028] Both the barrier layer and the base layer may be densified and / or compressed.

[0029] Densification may be carried out, for example, by wet or dry calendering. Wet calendering may further improve densification.

[0030] However, compression or densification may not be necessary to achieve the desired barrier properties. For example, a barrier layer may be formed by spraying the barrier layer material onto the base layer (or, in some embodiments, onto another additional layer). As another example, the barrier layer and base layer (and any additional layers, if present) may be formed in, for example, a two-ply or multi-ply headbox of a paper or board machine.

[0031] Densification and / or compression may, for example, provide a particular oxygen permeability to a multi-layer product. Densification and / or compression may, for example, provide a particular smoothness to a barrier layer.

[0032] The multi-layer product may be a formable product or a molded product.

[0033] The formable multi-layer product may be, for example, a sheet or a flat structure. Such formable multi-layer product may be formed into a final form having a desired shape. Various methods of forming the multi-layer product may be available.

[0034] The molded multi-layer product may be, for example, a container or receptacle, such as a cup or plate. However, the shape of the molded multi-layer product is not particularly limited.

[0035] The multi-layer product may be flexible or may be a flexible product, or alternatively, the multi-layer product may be rigid or may be a rigid multi-layer product.

[0036] The multilayer product may be, for example, a packaging material, packaging paper, wrapping paper, protective paper, packaging board, 3D packaging material, decorative paper, envelope, or release liner.

[0037] The multi-layer product may be formed primarily from cellulosic materials. However, the presence of trace amounts of non-cellulosic materials is not necessarily excluded in such multi-layer products. For example, a multi-layer product formed primarily from cellulosic materials may contain at least one non-cellulosic adhesive, such as glue, additives, colorants, or inks.

[0038] In some embodiments, the multi-layer product may be formed entirely from cellulosic materials.

[0039] In the context of this specification, the term "formed primarily from cellulosic materials" may refer to a multi-layer product in which at least 85% (w / w), or at least 95% (w / w), or at least 98% (w / w), or at least 99% (w / w), or 100% (w / w) of the materials are cellulosic.

[0040] The multi-layer article may be biodegradable. The multi-layer article may be biodegradable as determined by standard OECD 301F for the testing of chemical substances.

[0041] The term "biodegradable," at least in some embodiments, may refer to readily biodegradable (readily biodegradable) as determined by OECD 301F Standard for the Testing of Chemical Substances (manometric respirometry). A readily degradable multi-layer product may be a multi-layer product that reaches at least 60% biodegradability within 28 days as determined by OECD 301F Standard for the Testing of Chemical Substances.

[0042] The multi-layer product may be recyclable.

[0043] The base layer may include a reinforcing component. The reinforcing component may include, or may be, cellulose fibers, for example. Such cellulose fibers may be capable of imparting reinforcing properties to the multi-layer product. For example, they may be unmodified and / or unhydrolyzed. In other words, the reinforcing component of the base layer may be, for example, unmodified and / or unhydrolyzed cellulose fibers. The CED viscosity of the cellulose fibers of the base layer may be greater than 500 ml / g, for example, in the range of about 500 to 3000 ml / g. In some embodiments, the CED viscosity of the cellulose fibers of the base layer may be, for example, in the range of 800 to 1200 ml / g, or in the range of 900 to 1100 ml / g.

[0044] The fibers of the cellulose fibers (including the hydrolyzed or non-hydrolyzed cellulose fibers of the barrier layer, base layer, and / or any additional layers containing cellulose fibers, or the hydrolyzed or non-hydrolyzed cellulose fibers of the reinforcing component) may be natural fibers such as lignocellulosic fibers, cellulose fibers, cellulose fiber derivatives, wood derivatives, or any combination or mixture thereof. The fibers in the cellulose fibers may be natural-origin fibers, such as modified natural-origin fibers, and / or cellulosic fibers. The fibers in the cellulose fibers may be virgin fibers, regenerated fibers, secondary natural fibers, or any mixture or combination thereof. The cellulose fibers may be, for example, staple fibers. The cellulose fibers may be, for example, fibers derived from cotton or cotton linters. The cellulose fibers may include or be, for example, pulp. The pulp may include or be, for example, wood pulp (such as hardwood pulp and / or softwood pulp), non-wood pulp, and / or agropulp. The pulp may be a chemical pulp such as kraft pulp, soda pulp, sulfate pulp, or organosolv pulp. The pulp may be thermomechanical pulp (TMP), mechanical pulp (groundwood pulp (GW), pressure groundwood pulp (PGW), refined groundwood pulp (RMP)), and / or chemi-thermomechanical pulp (CTMP). Additionally or alternatively, the pulp may be a non-dried pulp such as non-dried kraft pulp. The cellulosic fibers or pulp may include recycled fibers or may be recycled fibers. The fibers in the cellulosic fibers may include at least one of wood pulp, non-wood pulp, staple fiber, recycled fiber, or any mixture or combination thereof, or may be at least one of wood pulp, non-wood pulp, staple fiber, recycled fiber, or any mixture or combination thereof. In some embodiments, the fibers in the cellulosic fibers may be free of man-made fibers and / or petroleum-based fibers.Staple fibers of a desired length may be combined with other types of reinforcing components, such as other types of cellulosic fibers.

[0045] In the context of this specification, the term "non-hydrolyzed cellulose fibers" may refer to cellulose fibers that have not been intentionally chemically hydrolyzed to a significant extent. However, non-hydrolyzed cellulose fibers may also be chemical pulps, such as kraft pulp, which may be bleached during the chemical pulp manufacturing process. For example, the kraft pulping process may result in mild hydrolysis of cellulose fibers, but the chemical pulp may still be considered to be or contain non-hydrolyzed cellulose fibers.

[0046] The reinforcing component or other cellulosic fibers may be or include chemical pulps such as kraft pulp, sulfate pulp, and / or organosolv pulp, and / or staple fibers.

[0047] The other cellulose fibers (e.g., cellulose fibers of the reinforcing component) may include or be natural and / or man-made cellulose fibers having a CED viscosity in the range of 500 to 3000 ml / g. Man-made cellulose fibers may, at least in some embodiments, have a lower CED viscosity.

[0048] In the context of the present disclosure, the term "hydrolyzed cellulose fibers" may be understood to refer to cellulose fibers that have undergone a process to at least partially hydrolyze the cellulose chains of the cellulose fibers, for example, compared to comparable non-hydrolyzed cellulose fibers. Accordingly, the average length of the cellulose chains of the hydrolyzed cellulose fibers may be less than the average length of the cellulose chains of comparable non-hydrolyzed cellulose fibers. Certain properties of the cellulose fibers, such as the CED viscosity, may be affected by hydrolysis. Hydrolyzed cellulose fibers may be obtainable or may be obtained, for example, by enzymatic hydrolysis of cellulose fibers using cellulolytic enzymes for 2 to 3 hours. The hydrolyzed cellulose fibers may be, or may include, for example, hydrolyzed pulp. In this context, the pulp of the hydrolyzed pulp may be any pulp described herein.

[0049] The hydrolyzed cellulose fibers may have a CED viscosity in the range of 50 to 500 ml / g, or 50 to 400 ml / g, hi some embodiments, the hydrolyzed cellulose fibers may have a CED viscosity in the range of 120 to 300 ml / g, or 140 to 200 ml / g.

[0050] The term "CED viscosity" may be understood to refer to the intrinsic viscosity in cupriethylenediamine (CED) solution. CED viscosity may be measured, for example, according to standard ISO 5351:2010.

[0051] The hydrolyzed cellulose fibers may have a degree of polymerization (DP) in the range of about 100 to 700, or in the range of about 120 to 300. The degree of polymerization may be measured, for example, using standard ISO 5351:2010(en). The degree of polymerization (DP) may be estimated from the CED viscosity value obtained according to the above standard according to the following formula: DP=0.75[μ] 1 / 0.905 In the formula, [μ] is the CED viscosity value.

[0052] Hydrolyzed cellulose fibers may, in some embodiments, be obtained by pretreatment or modification, for example, by surface modification, saponification of cellulose esters, or phosphorylation. Hydrolyzed cellulose fibers may, for example, bear evidence of a process that causes a change in surface chemistry.

[0053] The barrier layer may be formed from a material containing at least 10% (w / w) hydrolyzed cellulose fibers. The barrier layer, i.e., the barrier layer material, may contain, for example, at least 20% (w / w), or at least 30% (w / w), or at least 40% (w / w), or at least 50% (w / w), or at least 60% (w / w), or at least 70% (w / w), or at least 80% (w / w), or 100% (w / w) hydrolyzed cellulose fibers. The barrier layer, i.e., the barrier layer material, may be a mixture containing hydrolyzed cellulose fibers and other cellulose fibers (i.e., cellulose fibers of the reinforcing component and / or non-hydrolyzed cellulose fibers). The other cellulose fibers may be any of the cellulose fibers described herein, particularly any of the cellulose fibers described as reinforcing components. The hydrolyzed cellulose fibers and other cellulose fibers may differ from each other in properties such as degree of polymerization and / or CED viscosity. The proportions of hydrolyzed cellulose fibers and reinforcing components, e.g., other cellulose fibers, and optionally other components, may be selected to achieve the desired properties of the barrier layer. For example, increasing the proportion of hydrolyzed cellulose fibers may increase the density of the barrier layer, which may in turn reduce its tolerance to, for example, grease and / or oxygen. Thus, the proportion of hydrolyzed cellulose fibers may be selected to achieve a desired density, barrier properties, and / or smoothness. Other cellulose fibers, such as those of the reinforcing component (if present), may be provided in a desired proportion, for example, to provide the barrier layer with desired strength and / or other properties.

[0054] Barrier layers comprising hydrolyzed cellulose fibers may be densified or compressed so that the barrier layer has a desired density. Such barrier layers may have improved barrier properties and smoothness.

[0055] The proportion of at least 10% (w / w) hydrolyzed cellulose fibers may be understood as the dry weight of hydrolyzed cellulose fibers based on the total dry weight of the mixture from which the barrier layer is formed and / or the total dry weight of the layer.

[0056] The barrier layer, ie, the barrier layer material, may comprise about 10-90% (w / w) hydrolyzed cellulose fibers and about 10-90% (w / w) other cellulose fibers.

[0057] The barrier layer, ie, the barrier layer material, may comprise about 60-80% (w / w) hydrolyzed cellulose fibers and about 20-40% (w / w) other cellulose fibers.

[0058] The weight ratio of hydrolyzed cellulose fibers to other cellulose fibers may be in the range of about 30:70 to about 10:90, or in the range of about 40:60 to about 20:80.

[0059] The multi-layer product may further include a surface chemistry to provide barrier properties. The surface chemistry may be applied to the multi-layer product. The surface chemistry to provide barrier properties may include, for example, starch, wax, fatty acid, alkyl ketene dimer, alkyl succinic anhydride, thermoplastic component, or any combination or mixture thereof. Alternatively, the surface chemistry may be starch, wax, fatty acid, alkyl ketene dimer, alkyl succinic anhydride, thermoplastic component, or any combination or mixture thereof. The surface chemistry may or may not chemically react with the cellulose of the cellulose fibers, depending on its chemical properties. The surface chemistry may be covalently or non-covalently attached to the cellulose. The surface chemistry may physically attach to the cellulose. The surface chemistry may, for example, impregnate the barrier layer and / or base layer to provide the multi-layer product with desired physical properties.

[0060] The multi-layer product may further include a coating overlying the barrier layer and / or the base layer.

[0061] This coating may be the outermost layer of the multi-layer product.

[0062] The coating may be or may be applied as, for example, a hot melt coating, a dip coating, or a carton coating. Such a coating, for example a hot melt coating, may improve the heat seal properties of the multi-layer product.

[0063] The multi-layer product may further comprise a cellulose film layer, in other words, the multi-layer product may further comprise a coating that is a cellulose film layer.

[0064] The cellulose film layer may be formed by coagulating an alkali cellulose dope. The cellulose film layer may cover the barrier layer. The cellulose film layer may cover the barrier layer or any other layer, and thus the cellulose film layer may be the outermost layer of a multilayer product. The cellulose film layer may improve the oxygen and / or grease barrier properties of the multilayer product. However, such embodiments may not necessarily be formable. When the coating is a cellulose film layer, it may be biodegradable. Thus, the entire product may be cellulosic and optionally biodegradable, as opposed to, for example, a multilayer product that includes a plastic coating.

[0065] In the context of this specification, the term "alkali cellulose dope" may be understood as a solution containing cellulose solubilized in an alkaline solution, often a cold alkaline solution. For example, the alkali cellulose dope may be a cellulose spinning solution (i.e., an alkali cellulose spinning solution) or a cellulose solution (i.e., an alkali cellulose solution) for extrusion, spinning, electrospinning, molding, casting, film formation, film extrusion, cellulose pearl production, coating, spraying, and / or 3D printing. In other words, the term "alkali cellulose dope" may refer to a cellulose material in an alkaline solution suitable for use in, for example, spinning filaments, staple fibers, film production, cellulose pearl production, and various other purposes. The cellulose alkali cellulose dope may be coagulated under suitable conditions to form solid cellulose, such as type II cellulose.

[0066] Providing a cold alkaline solution may typically involve mixing and / or dissolving an alkaline agent such as NaOH, and optionally a dissolving or stabilizing agent, e.g., a zinc compound such as ZnO, with water. These may be mixed under conditions suitable for dissolving the components in water, e.g., at an elevated temperature, such that the alkaline agent such as NaOH is added at a concentration of at least 40% (w / w). The elevated temperature may be, for example, a temperature of at least 60°C. The resulting alkaline solution may then be diluted. The alkaline agent in the (cold) alkaline solution may, for example, include NaOH, LiOH, KOH, and / or any mixture or combination thereof, or may be NaOH, LiOH, KOH, and / or any mixture or combination thereof.

[0067] The cellulose film layer may be applied, for example, by calendering, such that the cellulose film is prepared by, for example, extruding and coagulating an alkali cellulose dope and separately preparing a multilayer product, and the multilayer product and cellulose film may be combined and calendered so that the cellulose film is adhered to the multilayer product to form the cellulose film layer.

[0068] Alternatively, the cellulose film layer may be formed by a surface treatment. The product may be surface-treated with, for example, a hydroxide such as NaOH, such that the cellulose fibers on the surface of the multi-layer product are at least partially solubilized and subsequently coagulated to form the cellulose film layer. The cellulose film layer formed by the surface treatment may be similar to a cellulose film layer prepared, for example, by coagulating an alkali cellulose dope.

[0069] The multilayer product may further include an adhesive layer between the base layer and the barrier layer. The multilayer product may also include an adhesive layer (or additional adhesive layers) between one or more other layers. The adhesive layer may attach the base layer and the barrier layer, and / or any other layers (depending on the embodiment and the presence and arrangement of layers) to one another. The adhesive may be, for example, a bio-based and / or biodegradable adhesive, such as a bio-based and / or biodegradable glue.

[0070] The multi-layer product may further comprise an ink layer and / or a lacquer layer, which may be formed, for example, by printing ink onto the surface of the multi-layer product or by lacquering the surface of the multi-layer product.

[0071] The base layer may be formed from a densified cellulosic fiber mixture.

[0072] The base layer may comprise at least 50% (w / w) kraft pulp and / or mechanical pulp and up to 50% (w / w) hydrolyzed cellulose fibers.

[0073] The base layer, ie, the base layer material, may comprise about 50-90% (w / w) kraft pulp and / or mechanical pulp, and about 10-50% (w / w) hydrolyzed cellulose fibers.

[0074] The base layer, ie, the base layer material, may comprise about 60-80% (w / w) kraft pulp and / or mechanical pulp, and about 20-40% (w / w) hydrolyzed cellulose fibers.

[0075] The base layer may comprise 100% non-hydrolyzed cellulosic fibers, such as kraft pulp and / or mechanical pulp.

[0076] The weight ratio of hydrolyzed cellulose fibers to non-hydrolyzed cellulose fibers in the base layer may range from about 10:90 to about 50:50.

[0077] The weight ratio of hydrolyzed cellulose fibers to non-hydrolyzed cellulose fibers in the base layer may range from about 20:80 to about 40:60.

[0078] The base layer may, for example, have a weight of at least 20 gsm, or in the range of 20 to 800 gsm, or in the range of 40 to 800 gsm (grams per square meter).

[0079] The barrier layer may have a thickness of 300 μm or less, or in the range of 1 to 200 μm, or in the range of 10 to 100 μm, or in the range of 10 to 40 μm.

[0080] The base layer and the barrier layer may be mechanically separable from each other. Such separation may be useful, for example, for recycling purposes. The layers may be mechanically separable, for example, depending on the manufacturing method used to prepare the multi-layer product and / or the presence and type of additives included in the multi-layer product. The separability of the base layer and the barrier layer may depend, for example, on the presence and composition of an adhesive layer disposed between the base layer and the barrier layer. The base layer and the barrier layer may be separated, for example, in a pulper, by suspending the base layer and the barrier layer in water to form particles and then separating the particles based on density.

[0081] The multi-layer product, in some embodiments, may be free of any plastics and / or metals.The multi-layer product, in some embodiments, may be free of inorganic materials such as pigments.

[0082] The multi-layer product is 100cm 3 / (m 2 The multi-layer product may have an oxygen transmission rate of 10 cm or less. 3 / (m 2 .day) or less, or 1cm 3 / (m 2The oxygen permeability may be measured at 23°C and 50% relative humidity. The oxygen permeability may be measured using a MOCON OX-TRAN® instrument. The instrument design and operation may conform to the ASTM D 3985 standard. In some embodiments, the oxygen permeability may be measured according to one of the standards ASTM D3985, ASTM F1927, or ISO 15105-2 using a Mocon Ox-Tran 2 / 21 MH instrument. In one embodiment, the oxygen permeability is measured at 23°C, 0% relative humidity, and 100% O2 for 1 day using a MOCON OX-TRAN instrument according to the ASTM D3985 standard.

[0083] The multi-layer product may have a Bendtsen air permeability (i.e., air permeability measured using a Bendtsen tester) of 100 ml / min or less. The multi-layer product may have a Bendtsen air permeability of 20 ml / min or less, or 5 ml / min or less. The Bendtsen air permeability value may be measured, for example, according to standard ISO 5636-3.

[0084] The composition of the multi-layer product, such as the presence or absence of surface chemistry, or densification and / or compression, may significantly affect water vapor permeability and oil permeability (e.g., as measured by heptane vapor transmission rate). Thus, the values ​​of such parameters may vary significantly for the multi-layer products according to the various embodiments described herein.

[0085] The water vapor transmission rate of the multilayer product is, for example, 1000 g / (m 2 .day) or less, or 100g / (m 2 .day) or less, or 20g / (m 2 The water vapor transmission rate may be determined at 23°C and 50% relative humidity.

[0086] The multilayer product may have a thickness of, for example, 50 g / (m 2 .day) or less, or 20g / (m 2 .day) or less, or 10g / (m 2The heptane vapor transmission rate may be determined at 23°C and 50% relative humidity.

[0087] The multilayer product may be semi-transparent and / or translucent, depending, for example, on the composition of the base layer, which may be densified to a degree that is translucent and / or semi-transparent.

[0088] The light transmittance of the product may be in the range of 0-70%, or in the range of 1-70%, or in the range of 20-70%. Light transmittance may be understood to refer to visible light transmittance. Light transmittance may be measured, for example, with an optical profiler.

[0089] Also disclosed are methods of making multi-layer articles according to one or more embodiments described herein.

[0090] The method may include forming a base layer and a barrier layer and forming a multi-layer product therefrom, for example, by adhering the base layer and the barrier layer (and optionally one or more additional layers) to one another.

[0091] The method may include providing a barrier layer material and a base layer material, forming the base layer and the barrier layer, and forming the multi-layer product therefrom, wherein the materials and compositions of the barrier layer and base layer materials may be in accordance with one or more embodiments described herein.

[0092] The method may include forming a base layer and a barrier layer simultaneously, thereby forming a multi-layer product. The base layer and barrier layer may be formed simultaneously, for example, in a two-layer or multi-layer headbox of a paper machine or board machine. If desired, additional layers may be formed simultaneously, or they may be attached to the multi-layer product. The resulting web forming both the base layer and the barrier layer (and optionally additional layers) may be densified or compressed, for example, by calendering. Densification may be carried out, for example, by wet or dry calendering. Wet calendering may further improve densification.

[0093] In some embodiments, a base layer may be formed, a barrier layer material comprising hydrolyzed cellulose fibers may be formed into a web, the web may be calendered to form the barrier layer, and the barrier layer may be applied onto the base layer, with an adhesive layer applied between the base layer and the barrier layer.

[0094] The web (which may form the barrier layer and / or both the base layer and the barrier layer) may be calendered. The web may be calendered using, for example, a nip pressure of 3 to 350 kN / m.

[0095] In some embodiments, the barrier layer may be formed by spraying the barrier layer material onto the base layer (or, in some embodiments, onto another additional layer).

[0096] The method may further include adding a coating, such as a cellulose film layer, to the multi-layer product.

[0097] The cellulose film layer may be applied by calendering. This may be done, for example, so that the cellulose film is prepared by, for example, extruding an alkali cellulose dope, coagulating it, and separately preparing a multilayer product. The multilayer product and the cellulose film may be combined and calendered so that the cellulose film is attached to the multilayer product to form the cellulose film layer.

[0098] A cellulose film layer may be added by coagulating an alkaline cellulose dope onto the multi-layer product.

[0099] The method may further include forming a cellulose film layer on the multilayer product by surface treatment. The multilayer product may be surface-treated with, for example, a hydroxide such as NaOH, such that cellulose fibers on the surface of the multilayer product are at least partially solubilized and subsequently coagulated to form a cellulose film layer. The cellulose film layer formed by the surface treatment may be similar to a cellulose film layer prepared, for example, by coagulating an alkali cellulose dope.

[0100] The method may further comprise the step of forming the product, which may be formed, for example, from a dry web. [Example]

[0101] Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings.

[0102] The following description discloses some embodiments in sufficient detail to enable those skilled in the art to utilize the embodiments based on the present disclosure. Not every step or feature of an embodiment is discussed in detail, as many steps or features will be apparent to those skilled in the art based on this specification.

[0103] FIG. 1A shows in cross-section one embodiment of a multi-layer product 1. The multi-layer product 1 comprises a base layer 2 based on cellulose fibers and a barrier layer 3. The barrier layer 3 covers the base layer 2 at least partially, or completely as shown in FIG. 1A. The multi-layer product 1 further comprises a coating 4. The coating 4 may be a cellulose film layer. The coating or cellulose film layer 4 is disposed on the barrier layer 3. The coating or cellulose film layer 4 covers the barrier layer 3 at least partially, or completely as shown in FIG. 1A. However, as will be understood by those skilled in the art, the coating 4 may alternatively or additionally be disposed on the base layer 2.

[0104] 1B shows another embodiment of a multi-layer product 1. This multi-layer product 1 is similar to that depicted in FIG. 1A, except that the multi-layer product 1 includes four layers: a base layer 2, two barrier layers 3 and 3′, and a cellulose film layer 4. The barrier layers 3 and 3′ are disposed on either side of the base layer 2. The cellulose film layer 4 is the outermost layer. The cellulose film layer 4 is disposed on one of the barrier layers 3.

[0105] 1C shows yet another embodiment of a multi-layer product 1. This multi-layer product 1 is similar to that depicted in FIG. 1B, except that the multi-layer product 1 includes four layers: two base layers 2 and 2′, a barrier layer 3, and a cellulose film layer 4. The base layers 2 and 2′ are disposed on either side of the barrier layer 3. The cellulose film layer 4 is the outermost layer. The cellulose film layer 4 is disposed on one of the base layers 4.

[0106] FIG. 1D illustrates yet another embodiment of a multilayer product 1. This multilayer product 1 is similar to that depicted in FIG. 1A, except that the multilayer product 1 further includes an adhesive layer 5 between the base layer 2 and the barrier layer 3. The adhesive layer 5 may extend between the base layer 2 and the barrier layer 3, adhering the base layer 2 and the barrier layer 3 to one another. The adhesive in the adhesive layer 5 may be, for example, any adhesive described herein. As one skilled in the art will appreciate, the adhesive layer 5 may also be included in the multilayer products illustrated in any one of FIGS. 1A-1C, for example.

[0107] The exemplary embodiments shown in Figures 1A-1D are flat or sheet-like and may be moldable or formed into a desired shape.

[0108] Example 1 The oxygen transmission rate (OTR) and grease permeability of the cellulose films were measured. The cellulose films were prepared by regenerating an alkali cellulose dope in citric acid with or without a plasticizer and drying the resulting films at 180°C and 410 kPa for 3 minutes. The oxygen transmission rate and grease permeability of the films were measured.

[0109] The oxygen permeability of the cellulose film at 23°C and 50% relative humidity is shown in Figure 2A, and the grease permeability at 40°C is shown in Figure 2B.

[0110] Example 2 The coating of a fiber composition (a fiber body, i.e., a base layer) with a cellulose film layer was evaluated. The cellulose film layer was directly applied by sandwiching the structure in a compression molding process. The base layer and the film layer were first conditioned in a suitable humidity chamber, and compression molding was carried out at 80°C for 20 minutes under a pressure of 410 kp or at 95°C for 20 minutes under a pressure of 650 kp. The preconditioning of the base layer and the film, and the applied pressure and temperature can be adjusted as needed.

[0111] A packaging material produced by compression molding a base layer with a cellulose film layer is shown in FIG.

[0112] Example 3 Coating of a fibrous composition (i.e., base layer) with a cellulose film applied by a calendering process was evaluated. The base layer and / or film was first conditioned in a suitable humidity chamber, and calendering was carried out at 80°C and 500 kp pressure, or at 100°C and 6000 kp pressure. The preconditioning of the base layer and film and the applied pressure and temperature can be adjusted as needed.

[0113] FIG. 4 shows a packaging material made by calendering a base layer with a cellulose film.

[0114] Example 4 The physical and mechanical properties of blends containing softwood kraft pulp fibers with different CED viscosities were evaluated. Pulp 1 refers to hydrolyzed softwood kraft pulp fibers with a CED of 166 ml / g, and Pulp 2 refers to hydrolyzed softwood kraft pulp fibers with a CED of 200 ml / g. The blend x:y represents the dry weight fiber mixture of softwood kraft pulp fiber to either Pulp 1 or Pulp 2. For example, 60:40 represents a blend with 60% softwood kraft pulp fiber and 40% Pulp 1 or Pulp 2. The physical and mechanical properties of the blends are shown in Figures 5A, 5B, and 5C, respectively.

[0115] FIG. 5A shows the apparent bulk density values ​​of certain fiber blends.

[0116] FIG. 5B shows the tensile index values ​​for certain fiber blends.

[0117] FIG. 5C shows the strain-to-break values ​​for certain fiber blends.

[0118] Example 5 Multilayer sheets were produced as two- or three-ply combinations by combining the base softwood layer with pulp 1 in different combinations. For example, a two-ply sheet was produced by laminating a pulp 1 layer to a softwood base layer. For three-ply, the pulp 1 layer was sandwiched between two softwood layers. The air permeability of the resulting multilayer structure was measured according to ISO 5636-3. The air permeability is shown in Figure 6.

[0119] It is obvious to those skilled in the art that with the advancement of technology, the basic idea may be implemented in various ways. Therefore, the embodiments are not limited to the above examples, instead, the embodiments may vary within the scope of the claims.

[0120] The embodiments described hereinbefore may be used in any combination with each other. Some of the embodiments may be combined together to form further embodiments. The processes, products, or uses disclosed herein may include at least one of the embodiments described hereinabove. It will be understood that the benefits and advantages described above may relate to one embodiment or to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or have any or all of the stated benefits and advantages. It will be further understood that reference to "an" or "an" item refers to one or more of those items. The term "comprising" is used herein to mean including the features or acts listed after the term "comprising" (before the term "including"), without excluding the presence of one or more additional features or acts.

Claims

1. A multilayer product (1) comprising a base layer (2) and a barrier layer (3) based on cellulose fibers, wherein the barrier layer comprises at least 10% (w / w) of hydrolyzed cellulose fibers, and the multilayer product further comprises a cellulose film layer (4).

2. The multilayer product according to claim 1, wherein the cellulose film layer is formed by solidifying an alkali cellulose dope.

3. The multilayer product according to claim 1 or claim 2, wherein both the base layer and the barrier layer are formed from a cellulose-based material.

4. A multilayer product according to claim 1 or 2, which is a packaging material, wrapping paper, wrapping paper, protective paper, packaging board, 3D material for packaging, decorative paper, envelope, or release liner.

5. The multilayer product according to claim 1 or claim 2, wherein the multilayer product is mainly formed from a cellulose-based material.

6. The multilayer product according to claim 1 or 2, wherein the multilayer product is biodegradable as determined by the OECD 301F standard for testing chemical substances.

7. The multilayer product according to claim 1 or claim 2, wherein the hydrolyzed cellulose fibers have a CED viscosity in the range of 50 to 500 ml / g, or in the range of 120 to 300 ml / g, or in the range of 140 to 200 ml / g.

8. The multilayer product according to claim 1 or claim 2, further comprising a surface chemical substance for providing barrier properties to be imparted to the multilayer product.

9. The multilayer product according to claim 1 or claim 2, further comprising an adhesive layer (5) between the base layer and the barrier layer.

10. The multilayer product according to claim 1 or claim 2, wherein the base layer is formed from a high-density cellulose fiber mixture and may contain at least 50% (w / w) kraft pulp and / or mechanical pulp and 50% (w / w) or less hydrolyzed cellulose fibers.

11. The multilayer product according to claim 1 or claim 2, wherein the base layer has a weight in the range of 20 to 800 gsm.

12. The multilayer product according to claim 1 or claim 2, wherein the barrier layer has a thickness of 300 μm or less, or in the range of 1 to 200 μm, or in the range of 10 to 100 μm, or in the range of 10 to 40 μm.

13. The multilayer product according to claim 1 or 2, wherein the multilayer product does not contain any plastic or metal.

14. The aforementioned multilayer product is 100 cm ３ / (m ２ (Days) or less, or 10 cm ３ / (m ２ (Days) or less, or 1 cm ３ / (m ２ A multilayer product according to claim 1 or claim 2, having the following oxygen permeability (in days).

15. The water vapor transmission rate of the multilayer product is 500 g / (m ２ ·day) or less, or 100 g / (m ２ ·day) or less, or 20 g / (m ２ ·day) or less. The multilayer product according to claim 1 or claim 2.

16. The aforementioned multilayer product is 50 g / m ２ . (Days) or less, or 20 g / (m) ２ . (Days) or less, or 10 g / (m³) ２ A multilayer product according to claim 1 or claim 2, having a heptane vapor transmission rate of the following (in days).

17. A method for manufacturing a multilayer product according to claim 1, comprising the steps of forming the base layer and the barrier layer, and forming the multilayer product from them, or a step of simultaneously forming the base layer and the barrier layer to form the multilayer product, and a step of forming the cellulose film layer.

18. The method according to claim 17, wherein the cellulose film layer is formed by solidifying an alkali cellulose dope.

19. The method according to claim 17 or 18, wherein the base layer is formed, the barrier layer material containing the hydrolyzed cellulose fibers is formed into a web, the web is calendered to form the barrier layer, the barrier layer is applied to the base layer, and an adhesive layer is applied between the base layer and the barrier layer.

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