Recyclable cellulose-based substrates including cellulosic fibers and non-fibrous cellulosic materials - Patent Application 20070122999

Abstract

The present invention relates to a cellulose-based substrate comprising natural cellulosic fibers and non-fibrous cellulosic material, which is recyclable by repulping and wherein at least 50% by weight of the substrate is recoverable according to EN 13430, a method for preparing the cellulose-based substrate, a method for processing the cellulose-based substrate, and the use of the cellulose-based substrate for packaging.

Description

[Technical Field]

[0001] The present invention relates to a recyclable cellulose-based substrate that can be used as a packaging material. Further aspects of the invention relate to methods for preparing the cellulose-based substrate and products derived therefrom. [Background technology]

[0002] Packaging materials generate a large amount of waste, and many countries are currently trying to reduce waste through recycling. Recyclable materials are advantageous because they extend the life of raw materials. For example, when cellulose-based materials are recycled by repulping, this can reduce the need for further growth and extraction of natural cellulose sources. Therefore, recycling by repulping promises economic and ecological benefits.

[0003] Parchment paper offers several advantages as a packaging material, such as providing grease and water resistance, providing a gas barrier, and being biodegradable and / or compostable. Furthermore, parchment-based products are generally considered safe for food contact and have long been used by consumers to package and / or prepare food. Parchment-based products can also be processed in multiple ways, such as by printing product labels.

[0004] Although they are generally biodegradable and / or compostable, parchment-based materials are generally not recyclable because the fibers are too strongly bound in an amorphous gel state. In other words, the advantageous properties of parchment-based food materials are accompanied by reduced recyclability and reduced economic and ecological benefits. Alternatively, for example, layered products in which a polymer film is bonded to a cellulose-based substrate require additional chemical and processing steps, which also cause negative environmental and economic impacts.

[0005] EP 3819426 discloses a highly parchmented cellulose-based paper with very low oxygen permeability. This material is compostable and / or biodegradable, but the repulpability of this material may be affected due to the fact that the fibers are embedded in a continuous cellulosic fiber matrix that includes non-fibrous cellulosic material.

[0006] US 2,023,711 discloses an attempt to prepare a partially parchmented paper substrate in which some cellulose fibers are dissolved while other cellulose fibers are unaffected. This is achieved by first passing the paper through a solution that protects the fibers from parchmentation, so that only uncoated fibers react with the parchmentation acid. However, the initial coating with the protection solution would further limit the recyclability and repulpability of the paper substrate.

[0007] Therefore, there is still room for improvement and a need for a cellulose-based packaging product with improved recyclability by repulping that still offers the advantageous properties of parchment paper. Summary of the Invention

[0008] The present invention solves the problems of the prior art by the following means.

[0009] In a first aspect, the present invention relates to a cellulose-based substrate comprising natural cellulosic fibers and non-fibrous cellulosic material, wherein the substrate is recyclable by repulping and at least 50% by weight of the substrate is recoverable according to EN 13430.

[0010] In a second aspect, the present invention relates to a method for preparing a substrate according to the first aspect, the method comprising: (i) providing a cellulose-based substrate precursor material comprising natural cellulosic fibers; (ii) partially infiltrating the cellulose-based substrate precursor material with a gelatinizing agent, thereby subjecting the cellulose-based substrate precursor material to reaction with the gelatinizing agent to dissolve the native cellulosic fibers and obtain a partially treated cellulose-based substrate precursor material; (iii) subjecting the partially treated cellulose-based substrate precursor material to a re-precipitation agent.

[0011] In a third aspect, the present invention relates to a method for processing a cellulose-based substrate according to the first aspect, wherein processing comprises any of printing, laminating, coating, painting, spraying, bonding, gluing, varnishing, impregnating, dipping, and / or bonding.

[0012] In a fourth aspect, the present invention relates to the use of a cellulose-based substrate according to the first aspect for packaging. [Brief explanation of the drawings]

[0013] [Figure 1] 1 shows a scanning electron micrograph of the sample of Example 1, where the parchmented portion containing non-fibrous cellulosic material can be seen at the surface. The remaining fibers in the core region remain unchanged from the untreated fibers. The inset of region A further shows that the parchmented portion containing non-fibrous cellulosic material in the surface region is approximately 5-10 μm thick. [Figure 2] The results of the oil resistance test performed on the samples of Example 1 are shown. Area A shows the treated area, which is more visible because the dye was not absorbed. Area B is untreated and is darker because the dye was absorbed. The picture on the right shows the other side of the board. Area C is the treated area where the dye did not penetrate. Area D is untreated and therefore has dye penetration. [Figure 3] A scanning electron micrograph of a sample of Example 2 shows that parchmented portions containing non-fibrous cellulosic material can be seen on the top and bottom surfaces, while the remaining fibers in the core region remain unchanged. [Figure 4]This shows the results of an oil resistance test performed on a sample from Example 2. On the blue line, the sample was subjected to a gelatinizing agent. Area A shows the treated area, which is more visible because the dye was not absorbed. Area B is untreated and is darker because the dye was absorbed. The picture on the right shows the other side of the board. Area C is the treated area where the dye did not penetrate. Area D is untreated and therefore has the dye penetrated. [Figure 5] 1 shows a photograph of the sample of Example 3, where the waterleaf partially covers the substrate. The top portion of the board is not covered by the waterleaf layer. [Figure 6] 1 shows a scanning electron micrograph of the sample of Example 3. As can be seen, the parchmented portion containing non-fibrous cellulosic material is located on the former water leaf layer, while the denser substrate material remains largely unchanged. The inset in area A further shows the parchmented portion of the surface region containing non-fibrous cellulosic material. [Figure 7] The results of the oil resistance test performed on the samples of Example 3 are shown. Area A shows the treated area, which is more obvious because the dye was not absorbed. Area B is untreated and is darker because the dye was absorbed. The picture on the right shows the other side of the board. Area C is the treated area where the dye did not penetrate. Area D is untreated and therefore has the dye penetrated. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention relates to a substrate comprising natural cellulosic fibers and non-fibrous cellulosic material, wherein the substrate is recyclable by repulping and at least 50% by weight of the substrate is recoverable according to EN13430.

[0015] definition In the context of the present invention, the following definitions and test methods apply.

[0016] As used herein, the term "fiber" refers to a material form characterized by a very high length-to-diameter ratio. Generally, cellulose fibers have a very wide range of diameters and lengths depending on the fiber type and fiber source. The average length of wood pulp fibers preferably used in the present invention is typically in the range of 0.3 mm to 3.5 mm, preferably 0.3 mm to 3.0 mm, more preferably 0.8 mm to 2.5 mm, and even more preferably 1.0 mm to 2.0 mm. The diameter of wood pulp fibers is typically in the range of 10 μm to 40 μm, preferably 15 μm to 35 μm, and even more preferably 20 μm to 30 μm. Therefore, the aspect ratio (ratio of fiber length to fiber diameter) of wood pulp fibers is typically in the range of 7.5 to 350, preferably 7.5 to 300, more preferably 10 to 200, and even more preferably 20 to 150. The terms "fiber" and "filament" can be used interchangeably for purposes of the present invention, unless otherwise specified.

[0017] The term "cellulose-based" describes a substrate and / or material and / or article that substantially comprises cellulose. The material may be a fiber or a film. The cellulose material is derived from man-made sources, such as regenerated cellulose fibers or films, or from natural sources, such as fibers or pulp from woody or non-woody plants. The cellulose-based material may comprise woven or non-woven cellulose. Non-woven cellulose-based materials may be formed from many processes, such as, for example, spin laying, carding, knitting, air laying, and wet laying processes. The basis weight of a cellulose-based material is typically measured as weight per unit area, e.g., grams per square meter (gsm = g / m 2 ) or ounces per square foot (osf). Cellulose-based materials can include natural cellulosic fibers and / or non-fibrous cellulosic materials.

[0018] The term "natural cellulosic fibers" refers to cellulose fibers from natural sources, such as woody plants, including deciduous and coniferous trees, or non-woody plants, including cotton, flax, esculenta, kenaf, sisal, abaca, milkweed, straw, jute, hemp, and bagasse. Preferably, the natural cellulosic fibers are suitable for dissolution by a gelatinizing agent. Suitable fibers for dissolution are, for example, hardwood fibers, softwood fibers, or annual plant fibers. The natural cellulosic fibers form a crystalline material containing a crystallized fraction with the crystalline morphology of cellulose I, which contains all parallel-oriented cellulose chains. The natural cellulosic fibers may have been subjected to a pulping step.

[0019] The term "non-fibrous cellulosic material" refers to a material obtained by reacting natural cellulosic fibers with a gelatinizing agent, thereby at least partially dissolving the natural cellulosic fibers, which disintegrate to form a gelatinized viscous material, and then removing the gelatinizing agent by washing with a re-precipitating agent, thereby precipitating the gelatinized material to form a solid material. One process for dissolving natural cellulosic fibers and re-precipitating them is referred to as the parchmentation process. The solid material referred to herein as non-fibrous cellulosic material is predominantly amorphous and may contain other forms of crystallized fractions, such as a crystallized fraction having the cellulose II crystalline morphology, which contains antiparallel cellulose chains. The non-fibrous cellulosic material is preferably a re-precipitated gelatinized cellulosic material.

[0020] The term "repulping" describes a process in which material that has previously undergone or been formed by at least one pulping step is subjected to a further pulping step.

[0021] The term "recyclable by repulping" describes a material that can be at least partially recovered during a repulping step and transformed into a new material or object. The material can be waste. The term "recyclable" is generally described in accordance with EN 13430. Thus, the expression "recyclable by repulping with at least 50% by weight recoverable according to EN 13430" describes a material that has been formed by or otherwise undergone at least one pulping step, from which at least 50% by weight of the substrate can be recovered when it is subjected to a further pulping step.

[0022] For ease of reference, the term "substrate", unless further specified, refers to a cellulose-based substrate according to the first aspect of the present invention.

[0023] Cellulose-based substrate As mentioned above, in a first aspect, the present invention relates to a cellulose-based substrate comprising natural cellulosic fibers and non-fibrous cellulosic material, wherein the substrate is recyclable by repulping and at least 50% by weight of the substrate is recoverable according to EN 13430.

[0024] In one embodiment of the first aspect, the substrate is recyclable by repulping, and at least 55% by weight of the substrate is recoverable according to EN 13430, more preferably at least 60% by weight of the substrate is recoverable according to EN 13430, more preferably at least 65% by weight of the substrate is recoverable according to EN 13430, at least 70% by weight of the substrate is recoverable according to EN 13430, more preferably at least 75% by weight of the substrate is recoverable according to EN 13430, more preferably at least 80% by weight of the substrate is recoverable according to EN 13430, more preferably at least 85% by weight of the substrate is recoverable according to EN 13430, and even more preferably at least 90% by weight of the substrate is recoverable according to EN 13430.

[0025] In one embodiment, the natural cellulosic fibers contained in the substrate are recycled by repulping. In one embodiment, the weight percent of the substrate that can be recovered during recycling by repulping is at most the amount of natural cellulosic fibers in the substrate. That is, all or most of the non-gelatinized cellulosic fibrous material that can be recovered during recycling by repulping can be considered recoverable natural cellulosic material in the sense of the present invention. Therefore, natural cellulosic material also includes fibers that have not reacted with a gelatinizing agent, or that have at most been partially reacted. In this sense, "partial" reaction defines a situation that allows the fibers to essentially maintain their fibrous state.

[0026] In one embodiment, the substrate comprises a composite material comprising natural cellulosic fibers and non-fibrous cellulosic materials. The substrate may be an article and / or a material.

[0027] In one embodiment, the natural cellulosic fibers and non-fibrous cellulosic material are contained in a continuous cellulosic fiber matrix. The term "continuous cellulosic fiber matrix" refers to a cellulosic material comprising natural cellulosic fibers and non-fibrous cellulosic material, where the natural cellulosic fibers are embedded in the non-fibrous cellulosic material, thereby blocking the pores of the fibrous framework. Thus, the continuous cellulosic fiber matrix represents a high-density material that provides a cellulose continuum between the natural cellulosic fibers and the non-fibrous cellulosic material, avoiding any voids at the interface between the natural cellulose fibers and the non-fibrous cellulosic material. Thus, the continuous cellulosic fiber matrix is ​​a continuous, non-porous material. The continuous cellulosic fiber matrix may have high gas barrier properties, particularly against oxygen.

[0028] In one embodiment, the continuous cellulosic fiber matrix further comprises destructured cellulosic fibers. The term "destructured cellulosic fibers" describes a periphery of native cellulosic fibers that have been partially dissolved with a gelatinizing agent, thereby producing a gradual structural change from native cellulose to precipitated cellulose. Such a gradual structural change means that the structure of the continuous cellulosic fiber matrix comprises a structural gradient, where the crystalline structure of the native cellulosic fibers slowly changes to the amorphous structure of the non-fibrous cellulosic material by forming destructured cellulosic fibers on the surface of the native cellulosic fibers. Thus, the destructured cellulosic fibers surround the native cellulosic fibers and interpose between the native cellulosic fibers and the non-fibrous cellulosic material. Preferably, the continuous cellulosic fiber matrix can be composed of native cellulosic fibers, destructured cellulosic fibers, and non-fibrous cellulosic material. Destructured cellulosic fibers that substantially retain their fibrous state and have undergone only minimal reaction with a gelatinizing agent can also be considered native cellulosic fibers.

[0029] In one embodiment, the substrate can be a substantially two-dimensional article, such as a sheet, or a three-dimensional article. A shaped article is an article that has been at least partially prepared by at least one molding step. A substantially two-dimensional article is an article that has length and width dimensions that are significantly greater than its thickness dimension. A two-dimensional article that encapsulates three shaped objects, thereby taking on the appearance of a three-dimensional article, such as a butter package, or that is otherwise not self-supporting, is also considered a two-dimensional article for the purposes of this application.

[0030] In one preferred embodiment of the first aspect, the substrate comprises: (i) providing a cellulose-based substrate precursor material comprising natural cellulosic fibers; (ii) partially infiltrating the cellulose-based substrate precursor material with a gelatinizing agent, thereby subjecting the cellulose-based substrate precursor material to reaction with the gelatinizing agent to dissolve the native cellulosic fibers and obtain a partially treated cellulose-based substrate precursor material; (iii) subjecting the partially treated cellulose-based substrate precursor to a re-precipitation agent.

[0031] In step (i) of a preferred embodiment of the first aspect of the present invention, a cellulose-based substrate precursor material is provided, comprising natural cellulosic fibers. The cellulose-based substrate has been formed by or otherwise undergone at least one pulping step. For ease of reference, the terms "precursor material" and "cellulose-based substrate precursor material" are used interchangeably herein. The precursor material may comprise at least 50% by weight natural cellulosic fibers, preferably at least 55% by weight natural cellulosic fibers, more preferably at least 60% by weight natural cellulosic fibers, more preferably at least 65% by weight natural cellulosic fibers, more preferably at least 70% by weight natural cellulosic fibers, more preferably at least 75% by weight natural cellulosic fibers, more preferably at least 80% by weight natural cellulosic fibers, more preferably at least 85% by weight natural cellulosic fibers, more preferably at least 90% by weight natural cellulosic fibers, and even more preferably at least 95% by weight natural cellulosic fibers. In one embodiment, the precursor material is substantially or entirely composed of natural cellulosic fibers. Preferably, the precursor material contains less than 1% by weight of non-fibrous cellulosic material.

[0032] In one embodiment, the precursor material may be any of the following: cardboard, waterleaf, absorbent paper, filter paper, and cellulosic tissue.

[0033] In step (ii) of a preferred embodiment of the first aspect, the precursor material is partially infiltrated with a gelatinizing agent. As used herein, "partially infiltrated" means that only a portion of the natural cellulosic fibers in the precursor material provided in step (i) are contacted with the gelatinizing agent, and the contacting is performed by infiltration. In one embodiment, 0.1 to 99% by weight of the natural cellulosic fibers in the precursor material are contacted with the gelatinizing agent, more preferably 0.1 to 50% by weight, more preferably 0.1 to 40% by weight, more preferably 0.1 to 30% by weight, more preferably 0.1 to 20% by weight, more preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and even more preferably 0.1 to 2% by weight.

[0034] In one embodiment, the gelatinizing agent is provided in liquid form, e.g., a solution, and includes at least one cellulose solvent selected from the group consisting of inorganic acids including sulfuric acid and phosphoric acid, Lewis acids including ZnCl and Ca(SCN), inorganic bases including NaOH, organic bases including N-methylmorpholine N-oxide, and ionic liquids including tetraalkylammonium salts. Preferably, the gelatinizing agent includes sulfuric acid.

[0035] In one embodiment, the precursor material is porous and can absorb the gelatinizing agent, thereby resulting in wetting when the precursor material comes into contact with the gelatinizing agent. The degree of wetting can be controlled by controlling the porosity of the precursor material, controlling the thickness of the precursor material, controlling the basis weight of the precursor material, controlling the pressure of contact with the gelatinizing agent (e.g., roller marks), controlling the contact time between the precursor material and the gelatinizing agent (e.g., immersing the precursor material in the gelatinizing agent for a predetermined time), adding a reprecipitation agent, etc. Preferably, the degree of wetting is controlled by controlling the porosity and thickness of the precursor material, as further described below.

[0036] In step (ii) of a preferred embodiment of the first aspect of the present invention, the precursor material provided in step (i) is partially infiltrated with a gelatinizing agent, and the precursor material is subjected to a reaction with the gelatinizing agent to dissolve the native cellulosic fibers and obtain a partially processed cellulose-based substrate precursor material. The reaction can be a chemical reaction. The extent to which the gelatinizing agent dissolves the native cellulosic fibers depends on the degree of infiltration, as the gelatinizing agent dissolves fibers with which it directly contacts. Furthermore, the extent to which the reaction occurs depends on the nature and concentration of the gelatinizing agent. For example, if 10% by weight of the precursor material is infiltrated with the gelatinizing agent, the gelatinizing agent may dissolve 10% by weight or less of the native cellulosic fibers in the precursor material. In one embodiment, the gelatinizing agent reacts with substantially all of the native cellulosic fibers with which it directly contacts, thereby dissolving all of the native cellulosic fibers with which it directly contacts. The reaction with the gelatinizing agent, and thus the dissolution of the native cellulosic fibers, results in a partially processed cellulose-based substrate precursor material. Thus, the partially processed cellulose-based substrate precursor material comprises natural cellulosic fibers and dissolved cellulosic fibers, the dissolved cellulosic fibers being a gel-like viscous material. Preferably, the partially processed cellulose-based substrate precursor material also comprises destructured cellulosic fibers.

[0037] In step (iii) of a preferred embodiment of the first aspect of the present invention, the partially treated cellulose-based substrate precursor is subjected to a re-precipitation agent. In one embodiment, all of the dissolved cellulosic fibers are subjected to the re-precipitation agent. In another embodiment, only a portion of the dissolved cellulosic fibers are subjected to the re-precipitation agent. Preferably, at least the dissolved cellulosic fibers are subjected to the re-precipitation agent.

[0038] The re-precipitation agent removes the gelatinizing agent, thereby interrupting the reaction between the gelatinizing agent and the native cellulosic fibers. Thus, the gelatinized viscous material containing the dissolved cellulosic fibers precipitates into a solid material, referred to herein as a "non-fibrous cellulosic material." The non-fibrous cellulosic material may be dry or wet. Preferably, the non-fibrous cellulosic material, together with the destructured cellulosic fibers and the native cellulosic fibers, forms a continuous cellulosic fiber matrix.

[0039] In one embodiment, the reprecipitation agent is water. In such embodiments, "removing the gelatinization agent" means diluting and washing away the gelatinization agent. Other reprecipitation agents that remove the gelatinization agent in other ways, for example, by neutralizing or otherwise inactivating the gelatinization agent, may be used.

[0040] A preferred embodiment of the first aspect of the present invention may comprise a further step (iv) in which the substrate is fixed by a drying step. Optionally, step (iv) may further comprise a separate washing step before the drying step.

[0041] In one embodiment, the precursor material provided in step (i) is provided in the form of a substrate precursor article. For ease of reference, the terms "substrate precursor article" and "precursor article" are used interchangeably herein. The precursor article can be a substantially two-dimensionally shaped article, e.g., a sheet, or a three-dimensionally shaped article. In one embodiment, the shaping step can occur during steps (ii) or (iii), or otherwise before the substrate is secured. In another embodiment, the shaping step can occur after the substrate is secured.

[0042] In one embodiment, the precursor material provided in step (i) is provided in the form of a substrate precursor article having at least one surface region and a core region, and the gelatinizing agent is infiltrated into the at least one surface region in step (ii). After infiltration of the at least one surface region, the precursor article is subjected to a reprecipitation agent, such that the at least one surface region comprises a non-fibrous cellulosic material. Preferably, after exposure to the reprecipitation agent, the at least one surface region comprises a continuous cellulosic fiber matrix.

[0043] In one embodiment, the gelatinizing agent does not infiltrate the core region, in which case the native cellulosic fibers within the core region remain intact and do not dissolve.

[0044] The at least one surface region is located substantially at the surface of the article, and the core region is located substantially at the majority of the article.

[0045] In one embodiment, the surface area penetrates at most 50%, more preferably at most 40%, more preferably at most 30%, more preferably at most 20%, more preferably at most 10%, more preferably at most 5%, more preferably at most 3%, and even more preferably at most 1% of the total thickness of the article.

[0046] In one embodiment, the surface area penetrates at most 5 cm into the article, more preferably at most 3 cm into the article, more preferably at most 1 cm into the article, more preferably at most 0.1 cm into the article, more preferably at most 1 mm into the article, more preferably at most 100 μm into the article, more preferably at most 50 μm into the article, and even more preferably at most 10 μm into the article.

[0047] The surface region may cover the entire surface of the precursor article, or only a portion thereof. The portion of the surface not covered by the surface region is referred to herein as the "remaining surface." For example, in one embodiment, the precursor article is a substantially two-dimensionally shaped article, such as a sheet, and the surface region covers only one side, with the other side being the remaining surface. In another embodiment, the precursor article is a concave, three-dimensionally shaped article, and the surface region covers only the inner surface of the concave article. Thus, the outer surface of the concave article is the remaining surface. In another embodiment, the precursor article is a cubic-shaped article, such as a box, and the surface region covers only one side. Thus, the other five sides constitute the remaining surface.

[0048] Controlling the infiltration of the gelatinizing agent into at least one surface region can be achieved by any suitable method. For example, the gelatinizing agent contacts only the surface region and not the remaining surfaces. This can be achieved, for example, by immersing the surface region in a solution containing the gelatinizing agent. Alternatively, the gelatinizing agent can be surface-applied to only one side of the sheet, for example, by rolling, spraying, kiss coating, transfer coating, and / or metered size pressing. The degree of infiltration can be controlled by controlling the porosity of the precursor article, controlling the thickness of the precursor article, controlling the basis weight of the precursor article, controlling the pressure of contact with the gelatinizing agent (e.g., roller marks), controlling the contact time between the precursor material and the gelatinizing agent (e.g., immersing the precursor material in the gelatinizing agent for a predetermined time), adding a reprecipitation agent, etc. Preferably, the degree of infiltration is controlled by controlling the porosity and thickness of the precursor article, as further described below.

[0049] In one embodiment, the precursor material provided in step (i) is provided in the form of a precursor article which is a multi-layer or single layer article. A multi-layer article may be a multi-layer sheet consisting of several layers stacked vertically on top of each other.

[0050] In one embodiment, the multilayer precursor article can include a first layer and a second layer, where the first layer is disposed on the surface of the article and is more permeable to the gelatinizing agent than the second layer. Preferably, at least the first and second layers are made of a cellulose-based material. The permeability of the layers can depend, for example, on the basis weight / density and / or Bendtsen porosity of the layers. As a result, the gelatinizing agent penetrates deeper into the first layer and reacts more strongly with the native cellulosic fibers. Thus, when the multilayer precursor article is subjected to a reprecipitation agent, the first layer contains more non-fibrous cellulosic material than the second layer. Preferably, the first layer contains a more continuous cellulosic fiber matrix.

[0051] In one embodiment, the second layer is substantially impermeable to the gelatinizing agent. Thus, after step (iii), the second layer does not contain non-fibrous cellulosic material and / or a continuous cellulosic fiber matrix. Preferably, the first layer contains more than 90% by weight of a continuous cellulosic fiber matrix, and the second layer contains less than 10% by weight of a continuous cellulosic fiber matrix.

[0052] In one embodiment, the second layer is disposed on the surface of the precursor article. In another embodiment, the second layer is disposed beneath the first layer throughout substantially the majority of the article. The precursor article may include an additional layer as the second layer, which may be more permeable, less permeable, or equally permeable to the gelatinizing agent.

[0053] In one embodiment, the precursor material provided in step (i) has a basis weight of at least 100 gsm, preferably at least 120 gsm, more preferably at least 140 gsm, more preferably at least 160 gsm, more preferably at least 180 gsm, more preferably at least 200 gsm, more preferably at least 220 gsm, more preferably at least 240 gsm, more preferably at least 260 gsm, and even more preferably at least 270 gsm. The precursor material may have a basis weight of less than 100 gsm, for example 70 gsm, although the precursor article, whose barrier properties and / or recovery rate may be affected, may have the same basis weight. Basis weight is preferably determined according to ISO 536:1995.

[0054] In one embodiment, the precursor material provided in step (i) is provided in the form of a precursor article that is a multilayer article, the multilayer article comprising a first layer and a second layer, the first layer being disposed on a surface of the article, the first layer having a basis weight of at most 270 gsm, more preferably at most 260 gsm, more preferably at most 240 gsm, more preferably at most 220 gsm, more preferably at most 200 gsm, more preferably at most 180 gsm, more preferably at most 160 gsm, more preferably at most 140 gsm, more preferably at most 120 gsm, more preferably at most 100 gsm, more preferably at most 80 gsm, more preferably at most 60 gsm, more preferably at most 40 gsm, and even more preferably at most 20 gsm. The basis weight of the first layer may be as low as 6 gsm.

[0055] In one embodiment, the precursor material provided in step (i) has a Bendtsen porosity of 2000 ml / min or less, preferably 1500 ml / min or less, more preferably 1000 ml / min or less, more preferably 900 ml / min or less, more preferably 800 ml / min or less, more preferably 700 ml / min or less, more preferably 600 ml / min or less, more preferably 500 ml / min or less, more preferably 400 ml / min or less, more preferably 300 ml / min or less, more preferably 200 ml / min or less, and even more preferably 100 ml / min or less. The precursor article may have the same Bendtsen porosity. The Bendtsen porosity is preferably measured according to ISO 5636-3:2013.

[0056] In one embodiment, the precursor material provided in step (i) has a thickness of 1200 μm or less, more preferably 1000 μm or less, and even more preferably 800 μm or less. The precursor material provided in step (i) preferably has a thickness of at least 10 μm. More preferably, the precursor material provided in step (i) has a thickness of at least 50 μm, more preferably at least 100 μm, more preferably at least 200 μm, and even more preferably at least 300 μm. The precursor articles may have the same thickness. The thickness is preferably measured according to TAPPI T 411.

[0057] Bendtsen porosity and thickness can be used in combination to control the degree of gelatinizing agent wetting. Substrates prepared from precursor materials and / or articles with relatively high Bendtsen porosity are believed to be less recyclable (while having relatively high barrier properties) than substrates prepared from precursor materials and / or articles with less porosity. Also, substrates prepared from precursor materials and / or articles with relatively high thickness are believed to be more recyclable than substrates with lower thickness. Therefore, preferably, the Bendtsen porosity and thickness of the substrate material and / or article are configured to achieve optimal barrier and / or recyclability performance.

[0058] In one embodiment, the precursor material has a Bendtsen porosity of 2000 ml / min or less and a thickness of 10 to 1500 μm, preferably a Bendtsen porosity of 1500 ml / min or less and a thickness of 50 to 1000 μm, and even more preferably a Bendtsen porosity of 1000 ml / min or less and a thickness of 100 to 800 μm. In a particularly preferred embodiment, the precursor material has a Bendtsen porosity of 200 to 1000 ml / min and a thickness of 300 to 800 μm. The precursor article can have the same combinations of porosity and thickness.

[0059] In one embodiment, the precursor material provided in step (i) is provided in the form of a precursor article that is a multi-layer article, the multi-layer article comprising a first layer and a second layer, the first layer being disposed on a surface of the article, and the first layer having a Bendtsen porosity of at least 100 ml / min, more preferably at least 200 ml / min, more preferably at least 300 ml / min, more preferably at least 400 ml / min, more preferably at least 500 ml / min, more preferably at least 600 ml / min, more preferably at least 700 ml / min, more preferably at least 800 ml / min, more preferably at least 900 ml / min, and even more preferably at least 1000 ml / min. In one embodiment, the second layer has a Bendtsen porosity of at most 500 ml / min, even more preferably at most 400 ml / min, even more preferably at most 300 ml / min, even more preferably at most 200 ml / min, even more preferably at most 100 ml / min, even more preferably at most 50 ml / min, and even more preferably at most 30 ml / min. The permeability of the layers correlates with their porosity. Thus, preferably, the porosity of the first and second layers is configured such that the first layer has a higher Bendtsen porosity than the second layer. Preferably, the first layer also has a lower thickness than the second layer, and preferably, the thickness of the first layer is at least 10 μm. In one embodiment, the thickness of the first layer is less than 50% of the total thickness of the first and second layers. Preferably, the thickness of the first layer is less than 40%, more preferably less than 30%, more preferably less than 20%, more preferably less than 10%, more preferably less than 5%, more preferably less than 3%, and even more preferably less than 1% of the total thickness of the first and second layers. The thickness of the first layer is preferably at least 0.0001% of the thickness of the first and second layers.

[0060] In one embodiment, the substrate is at least 90% by weight, preferably at least 95% by weight, and more preferably 100% by weight compostable according to EN 13432 and / or ASTM D6400. The term "compostable" is generally defined according to the EN 13432 standard. The term "compostable substrate" refers to a substrate in which at least 90% of the material must be biologically decomposed within six months under standard test method conditions, thereby meeting EN 13432. When applied to a material or product, the term "compostable" refers to the biodegradation and disintegration of the entire material or product. "Biodegradation" refers to the breakdown of a chemical structure or material under the action of microorganisms, while "disintegration" refers to the physical breakdown of a material or product made therefrom into small, visually indistinguishable fragments at the end of a typical composting cycle. To be considered a compostable polymeric material, the polymer chains must be degraded under the action of microorganisms so that total mineralization (i.e., conversion of the material into CO2, water, inorganic compounds, and biomass under aerobic conditions) is achieved at a high rate compatible with the normal composting process of vegetable waste.

[0061] In one embodiment, the substrate is fully compostable. In one embodiment, the portion of the substrate that is not recoverable by recycling by repulping is at least 90% by weight compostable according to EN13432 and / or ASTM D6400.

[0062] In one embodiment, the three-dimensional shaped substrate does not include plastic.

[0063] In one embodiment, the three-dimensional shaped substrate is food contact approved according to any of EU 1935 / 2004, BfR 36, BfR 36-1, BfR 36-2, FDA 21 CFA §176-170 and 176-180.

[0064] In one embodiment, the substrate is oil resistant according to TAPPI T454.

[0065] In one embodiment, the substrate is waterproof at 30 seconds watertight, preferably at 60 seconds watertight, more preferably at 180 seconds watertight, more preferably at 300 seconds watertight, more preferably at 600 seconds watertight, and even more preferably at 1800 seconds watertight, as determined according to TAPPI T441.

[0066] In one embodiment, the substrate is 200 cm 3 / (m 2 × days), more preferably 180 cm 3 / (m 2 × days), and even more preferably, 160 cm 3 / (m 2 × days), and even more preferably, 140 cm 3 / (m 2 × days), and even more preferably, 120 cm 3 / (m 2 × days), and even more preferably, 120 cm 3 / (m 2 × days), and even more preferably, 100 cm 3 / (m 2 × days), and even more preferably, 80 cm 3 / (m 2 × days), and even more preferably, 60 cm 3 / (m 2 × days), and even more preferably, 40 cm 3 / (m 2 × days), and even more preferably, 20 cm 3 / (m 2 x days) Oxygen transmission rate is measured according to ASTM D3985 and ASTM F 1927 at 23°C and 50% relative humidity.

[0067] In one embodiment, the substrate comprises only natural polymers. In the context of the present invention, natural polymers are naturally occurring, non-petroleum-based polymers such as rayon and hyaluronic acid, starch, or modified starches. Such natural polymers may be formed by living organisms, extracted, or chemically or physically modified by subsequent processes to convert them into a desired shape or form. In a preferred embodiment, the substrate does not contain petroleum-based synthetic polymer adhesives or pressure-sensitive adhesives.

[0068] In one embodiment, the substrate is a packaging article. The packaging article is an article configured to package a second article. The packaging article is not particularly limited in size and / or shape.

[0069] In one embodiment, the substrate is a food packaging article. In the food packaging article, the second article is a food or a food ingredient. The food packaging is not particularly limited and can be used to store food, such as oxygen-sensitive foods. The food packaging article can be a substantially two-dimensional shape, such as a butter package, or a three-dimensional shape, such as an egg carton or a soup bowl. The packaging article can be selected from, for example, a beverage container, a coffee capsule, a coffee pad, a chocolate packaging, and a biscuit packaging.

[0070] In one embodiment, the packaging article may be selected from any of a cosmetic packaging article, a medical packaging article, or an electronics packaging article.

[0071] Method for preparing a cellulose-based substrate In a second aspect, the present invention relates to a method for preparing a substrate according to the first aspect of the invention, the method comprising: (i) providing a cellulose-based substrate precursor material comprising natural cellulosic fibers; (ii) partially infiltrating the cellulose-based substrate precursor material with a gelatinizing agent, thereby subjecting the cellulose-based substrate precursor material to reaction with the gelatinizing agent to dissolve the native cellulosic fibers and obtain a partially treated cellulose-based substrate precursor material; (iii) subjecting the partially treated cellulose-based substrate precursor material to a re-precipitation agent.

[0072] In one embodiment, any of steps (i) to (iii) may be further characterized as in the embodiments relating to steps (i) to (iii) disclosed above. In addition, the method of the second aspect of the present invention may include a further step (iv) in which the substrate is fixed by a drying step. Optionally, step (iv) may further include a separate washing step before the drying step.

[0073] Processing of cellulose-based substrates In a third aspect, the present invention relates to a method for processing a substrate according to the first aspect of the invention.

[0074] In one embodiment, the processing comprises any of printing, laminating, painting, spraying, bonding, gluing, varnishing, impregnating, dipping, and / or bonding.

[0075] In one preferred embodiment, the substrate is a food packaging article and the processing comprises printing a label for the food packaging article.

[0076] Use of cellulose-based substrates In a fourth aspect, the present invention relates to the use of a substrate according to the first aspect of the invention for packaging.

[0077] In one embodiment, such uses may be directed to any of the shipping, storage, protection, preservation, and / or presentation of packaged items (e.g., gift wrapping).

[0078] In one embodiment, the packaging use is directed to food packaging, such as single-serving beverage capsules, cosmetic packaging, medical product packaging, and / or electronics packaging.

[0079] Based on the foregoing discussion, the examples below, and without wishing to be bound by theory, the inventors believe that this problem has been solved to provide a substrate with improved recyclability that can be used in packaging without compromising the advantageous properties of parchment-based materials. [Example]

[0080] In the examples, the following standard chemicals and conditions are used:

[0081] The material properties of the board-shaped precursor article are shown in tabular form below (Table 1). [Table 1]

[0082] Waterleaf layer: A highly porous sheet with a thickness of approximately 50 μm and a Bendtsen porosity of 1980 ml / min.

[0083] Gelatinizing agent: sulfuric acid with a concentration of 70% to 75%.

[0084] Impregnation methods: In one example, the cellulosic substrate is immersed in a sulfuric acid bath; in another example, sulfuric acid is deposited on one corner of the sample and a silicone roll is used to spread the acid over the surface of the sample on the same side.

[0085] Imaging method: Scanning electron microscope (SEM) and / or digital photography

[0086] Bendtsen porosity was measured according to ISO 5636-3:2013.

[0087] Beck smoothness was measured according to ISO 5627:1995.

[0088] The thickness was measured according to TAPPI T 411.

[0089] Basis weight is determined in accordance with ISO 536:1995.

[0090] Oil resistance testing was performed according to Tappi T-454:2015.

[0091] The recyclability test was carried out according to EN 13430. A given sample was cut into approximately 25 cm 2 The repulped samples were screened on a Somerville-type apparatus using a 0.15 mm slot plate according to test method TAPPI / ANSI T 275 sp-18. The different recovered fractions were used to calculate the recoverable portion.

[0092] Example 1 Sulfuric acid was deposited on one corner of the board-shaped precursor, and a silicone roll was used to spread the acid across the surface of the same side of the sample. The sample was then rinsed with running water and dried. Figure 1 shows a scanning electron micrograph of the cross section of the sample. As can be seen, only the surface area is parchmented, while the core area remains substantially unchanged.

[0093] The samples were then subjected to an oil resistance test. An oil-based dye was spread on the treated side and the reverse side was observed. As can be seen in Figure 2, the dye penetrated only into the untreated areas.

[0094] Example 2 The board-shaped precursor article was immersed in a sulfuric acid bath. The sample was then rinsed with running water and dried. This process treated both sides of the board.

[0095] The recyclability of the substrates was then tested and compared to industrial samples, the results of which can be seen in Table 2 below. [Table 2]

[0096] 3 and 4 show a cross-sectional SEM image and an oil resistance test result of the sample of Example 2, respectively.

[0097] Example 3 A two-layer precursor article was prepared by placing a water leaf layer on one side of a board-shaped precursor article such that the water leaf layer covered only about 80% of the board-shaped precursor article, and the total thickness of the precursor article was about 616 μm when covered with water leaf and 566 μm when not covered.

[0098] Sulfuric acid was deposited on the side of the board-shaped precursor containing the water leaf layer, on the side of the sample containing only the board. A silicone roll was then used to roll the acid onto the water leaf while simultaneously pressing the gel, spreading the acid to the opposite side of the sample. The sample was then rinsed with running water and dried.

[0099] 5 to 7 show a photograph, a cross-sectional SEM image, and an oil resistance test result of the sample of Example 3, respectively.

Claims

1. 1. A cellulose-based substrate comprising natural cellulosic fibers and non-fibrous cellulosic materials, wherein the substrate is recyclable by repulping, and wherein at least 50% by weight of the substrate is recoverable in accordance with EN 13430.

2. The substrate is (i) providing a cellulose-based substrate precursor material comprising natural cellulosic fibers; (ii) partially infiltrating the cellulose-based substrate precursor material with a gelatinizing agent, thereby subjecting the cellulose-based substrate precursor material to reaction with the gelatinizing agent to dissolve the native cellulosic fibers and obtain a partially treated cellulose-based substrate precursor material; (iii) subjecting the partially treated cellulose-based substrate precursor material to a re-precipitation agent.

3. 3. The cellulose-based substrate of claim 2, wherein the cellulose-based substrate precursor material provided in step (i) is provided in the form of a substrate precursor article having at least one surface region and a core region, and wherein the gelatinizing agent infiltrates the at least one surface region.

4. 4. The cellulose-based substrate of claim 2 or 3, wherein the cellulose-based substrate precursor material provided in step (i) is provided in the form of a substrate precursor article that is a multi-layer or a single-layer article.

5. 5. The cellulose-based substrate of claim 4, wherein the substrate precursor article is a multilayer article comprising a first layer and a second layer, the first layer being disposed on a surface of the article, and the first layer being more permeable to the gelatinizing agent than the second layer.

6. The cellulose-based substrate precursor material provided in step (i) a basis weight of at least 100 gsm, and / or The cellulose-based substrate according to any one of claims 2 to 5, having a Bendtsen porosity of less than or equal to -2000 ml / min.

7. 7. The cellulose-based substrate according to any one of claims 1 to 6, wherein the substrate is recyclable by repulping, and wherein at least 75% by weight of the substrate is recoverable according to EN 13430, more preferably at least 90% by weight of the substrate is recoverable according to EN 13430.

8. The substrate is - at least 90% by weight compostable according to EN 13432, and / or The cellulose-based substrate according to any one of claims 1 to 7, which is approved for food contact according to any of EU 1935 / 2004, BfR 36, BfR 36-1, BfR 36-2, FDA 21 CFA § 176-170 and 176-180.

9. The substrate is - oil resistant according to TAPPI T454, and / or - Watertight for 60 seconds without leakage as determined in accordance with TAPPI T441; and / or 9. The cellulose-based substrate of any one of claims 1 to 8, having an oxygen transmission rate of less than 200 cm3 / (m2 x day) when determined at -23°C and 50% relative humidity.

10. The cellulose-based substrate according to any one of claims 1 to 9, wherein the substrate comprises only natural polymers.

11. 11. The cellulose-based substrate of any one of claims 1 to 10, wherein the substrate is a packaging article, and further optionally, the substrate is any of a food packaging article, a cosmetic packaging article, a medical packaging article, or an electronics packaging article.

12. A method for preparing a cellulose-based substrate according to any one of claims 1 to 11, comprising the steps of: (iv) providing a cellulose-based substrate precursor material comprising natural cellulosic fibers; (v) partially infiltrating the cellulose-based substrate precursor material with a gelatinizing agent, thereby subjecting the cellulose-based substrate precursor material to reaction with the gelatinizing agent to dissolve the native cellulosic fibers and obtain a partially treated cellulose-based substrate precursor material; (vi) subjecting the partially treated cellulose-based substrate precursor material to a re-precipitation agent.

13. 13. The method of claim 12, wherein the re-precipitating agent in step (iii) is water.

14. 12. A method for processing a cellulose-based substrate according to any one of claims 1 to 11, wherein said processing comprises any of printing, laminating, coating, painting, spraying, bonding, gluing, varnishing, impregnating, dipping, and / or bonding.

15. Use of a cellulose-based substrate according to any one of claims 1 to 11 for packaging, preferably for packaging food, electronics, cosmetics and / or medical products.

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