Metallized paper multilayer packaging material

Abstract

The present invention relates to a cellulosic substrate comprising or consisting of a cellulose graft copolymer having polypeptide branches. The present invention also relates to a packaging material, particularly a metallized paper-based multilayer packaging material, comprising at least one paper layer comprising or consisting of a cellulose graft copolymer having polypeptide branches.

Description

[Technical Field]

[0001] The present invention relates to a paper-based multilayer packaging material comprising a paper layer and an ultra-thin metal or metalloid layer for water vapor barrier sandwiched between ultra-thin coating layers that provide oxygen barrier and hermeticity to the structure. More precisely, the present invention relates to a paper-based multilayer packaging material in which the paper layer comprises a cellulose graft copolymer with polypeptide branches. [Background technology]

[0002] Plastic packaging is frequently used in economic activities and people's daily lives. Plastic packaging has several advantages, such as flexibility and light weight. Lightweighting contributes to fuel savings and CO2 reduction, for example during transportation. The barrier properties of plastic packaging have a positive effect on extending shelf life and therefore help reduce food waste. Barrier properties also help ensure food safety.

[0003] However, due to increasing environmental awareness and to ensure a reduction in plastic waste, multi-layer packaging materials have been developed that comprise one paper or cardboard layer and one or more plastic or metal film layers to provide robustness and barrier properties, particularly oxygen and moisture barrier properties.

[0004] Recently, there has been an increased environmental awareness, especially with regard to waste materials, such as used packaging, that are not recycled or properly treated. This problem is considered very serious by the industry, which is devoting a great deal of effort to developing new packaging materials that are quickly and easily recyclable.

[0005] Currently, when producing multi-layer packaging structures, if layers of plastic are applied by known techniques, in particular by extrusion (extrusion lamination) or also by adhesive lamination processes, the thickness of the plastic film obtained on the paper is necessarily large.

[0006] Even when the extruded or laminated polymers in such multilayer structures are relatively thin, the cohesive strength of the polymer film is very high, as is the level of adhesion of the polymer to the paper or cardboard (i.e., cellulosic) substrate, which prevents the polymer from being removed from the substrate during recycling and prevents recycling and repulping of the cellulose fiber portion in the paper-stream recycling process.

[0007] Thus, later during the recycling process, multi-layer structures comprising a combination of paper and extruded or adhesively laminated (by conventional techniques such as extrusion lamination or extrusion coating) plastic (polymer) films have limited recyclability in standard paper recycling processes because the plastic layers are too thick to be dispersed and have too high a cohesive strength and adhesion level to adjacent layers of the structure to separate them from other layers of material, especially from the paper fibers. The extruded plastic film remains intact in the paper pulp tank, thus making it difficult to recycle the paper pulp through a repulping process.

[0008] Furthermore, the above-mentioned known recycling processes for laminated materials are expensive, energy consuming, and characterized by a relatively low yield of recycled paper fibers (less than 80% of the total amount of packaging material in the entire structure), and therefore are not sufficiently environmentally friendly in terms of disposal and recycling. There is also room for improving the recyclability of the remaining parts of the packaging material (i.e., the plastic polymer part and the metal part, e.g., the aluminum part) in the paper recycling process.

[0009] Furthermore, in packaging for food products, good barrier properties are essential to maintain the safety and quality of the packaged food, and typically such barrier properties include gas barrier, e.g., to oxygen and water vapor (moisture), and possibly also liquid-tightness.

[0010] One way to provide a good moisture barrier to paper-based packaging materials is the introduction of a metal or metalloid layer into a so-called "metallized" layer. As used herein, the term "metallization" (e.g., in the expression "metallized barrier paper layer") is meant to encompass the deposition of metal or metalloid atoms on the surface of paper or paperboard. One can even consider embodiments that include the deposition of alloys of metals and metalloids. Metalloids have some of their properties close to metals. Aluminum oxide and silicon oxide are examples of metalloids.

[0011] Problems associated with the introduction of metal layers into paper-based packaging materials include the sensitivity of the metal layer to mechanical stress, as well as poor adhesion of the metal to the paper surface, poor smoothness, and high porosity of the paper material. Mechanical stress can easily result, for example, in the loss of the necessary barrier properties that the metallized packaging material is intended to provide. Mechanical stress can result, for example, from the processing of multilayer materials in the manufacture of packages using form-fill-seal packaging machines. During manufacturing, materials are stretched, bent, rolled, compressed, and / or heated during the forming and sealing of packages using conventional packaging forming methods. These packaging manufacturing processes impose high mechanical and / or chemical stresses on the materials, particularly on ultra-thin metallized layers of metal or metalloid, resulting in the development of mostly irreversible damage, cracks, and tears in these layers.

[0012] In view of the above, there is a need for a metallized paper-based multi-layer packaging material that simultaneously exhibits the following properties: sufficient barrier properties, particularly barrier properties to oxygen and moisture; high resilience to mechanical stresses, such that the material maintains the same level of barrier even when subjected to transforming processes, such as those used to manufacture the package; a significantly reduced plastic polymer content compared to the content of cellulosic materials; and, preferably, recyclability in paper recycling processes and / or biodegradability in a variety of environmental conditions, particularly (but not exclusively) in marine environments.

[0013] [Summary of the Invention] The inventors have surprisingly found that grafting a polypeptide onto cellulose (e.g., via succinic acid or citric acid) improves the resilience of a paper layer containing a cellulose graft copolymer, and as a result, improves the mechanical properties of the entire multilayer packaging material comprising the paper layer.

[0014] Thus, the inventors have overcome the technical limitations of known multilayer barrier structures and have provided a multilayer structure for packaging that has excellent barrier properties against oxygen and moisture transmission, and resistance to liquid contact from its interior or exterior surfaces, while achieving a high total cellulose fiber content.

[0015] Furthermore, the inventors have succeeded in forming a multilayer structure completely free of polymer layers formed by extrusion lamination and / or adhesive lamination, thereby providing a multilayer structure having a ratio of cellulosic fibers to non-cellulosic materials and an extremely high fiber content. In this structure, the polymer layer easily decomposes during the repulping process due to the water solubility of the pre-coating layer. Furthermore, the relatively high adhesion of the post-metallization (or post-metalloidization) polymer to the metallized layer inhibits fragmentation of the metal layer during repulping, resulting in high fiber purity. Therefore, the resulting structure exhibits excellent repulping performance and a high yield of high-quality fibers, making it acceptable for standard paper recycling mills in most countries. Due to the extremely low content of non-cellulosic polymers and vacuum-deposited metallic materials, the entire material of the present invention is easily decomposed, dissolved, and separated in recycling processes designed for cellulosic materials such as paper or cardboard, unlike existing multilayer barrier structures known in the art.

[0016] In one aspect, the present invention provides a cellulosic substrate comprising or consisting of a cellulose graft copolymer comprising polypeptide branches. The cellulose graft copolymer may be any of those described herein. The cellulosic substrate may be a paper substrate, a paperboard substrate, or a cardboard substrate.

[0017] In one aspect, the present invention provides a packaging material comprising at least one paper layer comprising or consisting of a cellulose graft copolymer comprising polypeptide branches. The cellulose graft copolymer may be any of those described herein. The packaging material may be a metallized paper-based multilayer packaging material.

[0018] In one embodiment, the present invention provides a metallized paper-based multilayer packaging material (1), comprising: (i) 30 to 120 g / m 2 and (ii) at least one organic barrier layer (3) of a polymer selected from the list of polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butenediol vinyl alcohol copolymer (BVOH), or a combination thereof, having a basis weight in the range of 0.5 to 20 g / m. 2 Amount of, preferably 1 to 10 g / m 2 More preferably, the amount is 2 to 8 g / m 2 (iii) at least one inorganic barrier layer (4) selected from the list of metals, metalloids, or combinations thereof, having a thickness of 1 to 100 nm; and (iv) at least one organic heat seal layer (5) comprising a heat sealable polymer, having a thickness of 2 to 20 g / m. 2 Amount of 4 to 9 g / m 2 and an organic heat seal layer (5) applied in an amount of

[0019] The inorganic layer may comprise a metal or metalloid selected from the list of aluminum, aluminum oxide (AlOx), or silicon oxide (SiOx), the metal and / or metalloid being deposited by either vacuum deposition or transfer metallization. The heat-seal layer may comprise an acrylic or methacrylic polymer grafted with at least one ionomer, preferably a sodium ionomer. Preferably, the ionomer-grafted acrylic or methacrylic polymer has a molecular weight of 85-90 g / mol. Each of the organic layers may be deposited on the adjacent layer by either aqueous dispersion or aqueous solution deposition.

[0020] In some embodiments, the paper layer (2) is covered on its outer surface with an ink layer (6). Preferably, the ink layer is selected from the list of water-based ink, solvent-free ink, or a combination thereof. In some embodiments, the paper layer or ink layer is covered on its outer surface with an outermost layer (7) of overprint varnish (OPV). Preferably, the outermost overprint varnish layer (7) is a styrene acrylic varnish.

[0021] Packaging material: 0.5g / m 2 / day (measured at 23°C and 85% relative humidity), and / or a water vapor transmission rate (WVTR) of less than 0.1 cm 3 / m 2 / day bar (measured at 23°C and 50% RH). The packaging material may have a strain at break under in-plane tensile load of up to 5% in the machine direction of the paper and up to 15% in the cross-machine direction.

[0022] In one aspect, the present invention provides a three-dimensional sealed packaging article made from a packaging material according to the present invention, obtainable by shaping said packaging material, filling it with an edible product for human or animal consumption and then sealing it.

[0023] In one aspect, the present invention provides the use of a cellulose graft copolymer comprising polypeptide branches (as described herein), a cellulosic substrate according to the present invention, or a packaging material according to the present invention for packaging an edible product for human or animal consumption.

[0024] In one aspect, the present invention provides a packaged edible product filled with an edible product for human or animal consumption, comprising a cellulose graft copolymer (as described herein) comprising polypeptide branches, a cellulosic substrate according to the present invention, or a packaging material according to the present invention.

[0025] In one aspect, the present invention provides a cellulose graft copolymer comprising polypeptide branches.

[0026] Any suitable polypeptide can be grafted onto the cellulose backbone. In some embodiments, the polypeptide is collagen or a hydrolyzed form thereof. The polypeptide branches can be attached to cellulose by any suitable method. The polypeptide branches can be attached to cellulose by a linker. In some embodiments, the polypeptide branches are attached to cellulose by a polycarboxylic acid or anhydride thereof. In some embodiments, the polypeptide branches are attached to cellulose by a tricarboxylic acid or anhydride thereof. In some embodiments, the polypeptide branches are attached to cellulose by a tricarboxylic acid selected from one or more of citric acid, isocitric acid, aconitic acid, or tricarballylic acid, or anhydrides thereof. In some embodiments, the polypeptide branches are attached to cellulose by citric acid or anhydrides thereof. In some embodiments, the polypeptide branches are attached to cellulose by citric acid. In some embodiments, the polypeptide branches are attached to cellulose by a dicarboxylic acid or anhydride thereof. In some embodiments, the polypeptide branches are attached to the cellulose by a dicarboxylic acid selected from one or more of malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid, or anhydrides thereof. In some embodiments, the polypeptide branches are attached to the cellulose by a succinic acid or anhydride thereof. In some embodiments, the polypeptide branches are attached to the cellulose by a succinic anhydride.

[0027] In one aspect, the invention provides a method for grafting a polypeptide onto cellulose, the method comprising the steps of: (a) functionalizing cellulose with a linker molecule to provide a functionalized cellulose; and (b) grafting a polypeptide onto the functionalized cellulose to provide a cellulose graft copolymer comprising polypeptide branches.

[0028] Any suitable polypeptide may be used. In some embodiments, the polypeptide is collagen or a hydrolyzed form thereof. The cellulose may be functionalized with any suitable linker molecule. In some embodiments, the linker molecule is a polycarboxylic acid or anhydride thereof. In some embodiments, the linker molecule is a tricarboxylic acid or anhydride thereof. In some embodiments, the linker molecule is a tricarboxylic acid selected from citric acid, isocitric acid, aconitic acid, or tricarballylic acid, or one or more of their anhydrides. In some embodiments, the linker molecule is citric acid or anhydride thereof. In some embodiments, the linker molecule is citric acid. In some embodiments, the linker molecule is a dicarboxylic acid or anhydride thereof. In some embodiments, the linker molecule is a dicarboxylic acid selected from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid, or one or more of their anhydrides. In some embodiments, the linker molecule is succinic acid or anhydride thereof. In some embodiments, the linker molecule is succinic anhydride. Any suitable reaction conditions can be used to functionalize cellulose. Preferably, the polycarboxylic acid or its anhydride is incubated with a nucleophilic catalyst, and optionally, the nucleophilic catalyst is 4-dimethylaminopyridine (DMAP).

[0029] Any suitable reaction conditions can be used to graft the polypeptide chain to the cellulose. Preferably, the polypeptide chain is grafted to the functionalized cellulose by a carbodiimide crosslinking reaction. In some embodiments, the carbodiimide crosslinking agent is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC), and optionally, N-hydroxysuccinimide (NHS) is included in the carbodiimide crosslinking reaction.

[0030] In one aspect, the present invention provides a cellulose graft copolymer obtained or obtainable by the method according to the present invention.

[0031] In one aspect, the present invention provides a functionalized cellulose, wherein the functionalized cellulose is functionalized with a polycarboxylic acid or an anhydride thereof.

[0032] In some embodiments, the functionalized cellulose is functionalized with a tricarboxylic acid or an anhydride thereof. In some embodiments, the functionalized cellulose is functionalized with a tricarboxylic acid selected from citric acid, isocitric acid, aconitic acid, or tricarballylic acid, or one or more of their anhydrides. In some embodiments, the functionalized cellulose is functionalized with citric acid or an anhydride thereof. In some embodiments, the functionalized cellulose is functionalized with citric acid. In some embodiments, the functionalized cellulose is functionalized with a dicarboxylic acid or anhydride thereof. In some embodiments, the functionalized cellulose is functionalized with a dicarboxylic acid selected from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid, or one or more of their anhydrides. In some embodiments, the functionalized cellulose is functionalized with succinic acid or anhydride thereof. In some embodiments, the functionalized cellulose is functionalized with succinic anhydride. [Brief explanation of the drawings]

[0033] Additional features and advantages of the present invention are described in, or will be apparent from, the following description of the presently preferred embodiments, which proceeds with reference to the drawings. [Figure 1] FIG. 1 shows an example of a reaction scheme for grafting collagen onto cellulose by two-step coupling with succinic anhydride. [Figure 2]Figure 2 demonstrates the improved hydrophobicity of handsheets formed from the recovered grafted cellulose fibers. (A) Illustrative photographs showing water droplets on small pieces of handmade paper with and without grafted collagen. (B) Contact angles over time for handmade paper with and without grafted collagen. (C) Percent change in contact angle for handmade paper with and without grafted collagen for various amounts of water. [Figure 3] Figure 3 confirms the presence of collagen protein in the recovered grafted cellulose fibers. (A) SEM image and EDX measurements of dry cellulose fibers. (B-C) SEM image and EDX measurements of wet cellulose fibers: (B) EDX measurements performed on the background; (C) EDX measurements performed on the fibers. [Figure 4] FIG. 4 shows an example of a reaction scheme for grafting collagen onto cellulose by two-step coupling with citric acid. [Figure 5] FIG. 5 shows a first embodiment of a multilayer structure according to the invention. [Figure 6] FIG. 6 shows a second embodiment of a multilayer structure according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] Various preferred features and embodiments of the present invention will now be described by way of non-limiting example, it being understood that those skilled in the art can combine all features of the invention disclosed herein without departing from the scope of the invention as disclosed.

[0035] It should be noted that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless otherwise indicated. As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," "containing," or "contains" and are all-inclusive, i.e., open-ended, and do not exclude additional, unrecited components, elements, or steps. The terms "comprising," "comprises," and "comprised of" also include the term "consisting of." Numerical ranges are inclusive of the numbers defining the range.

[0036] All publications mentioned herein are incorporated herein by reference. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Any publications cited herein should not be construed as an admission that they constitute prior art to the claims appended hereto.

[0037] cellulose graft copolymer In one aspect, the present invention provides a graft copolymer comprising a cellulose backbone and polypeptide branches.

[0038] As used herein, a "graft copolymer" can refer to a branched copolymer having one or more polymer branches attached to a main polymer backbone, where the components of the branches are structurally different from the components of the main chain (see, for example, Feng, C., et al., 2011. Chemical Society Reviews, 40(3), pp. 1282-1295). The graft copolymer "backbone" is sometimes referred to as the "main chain," and the graft copolymer "branches" are sometimes referred to as "side chains" or "pendants."

[0039] cellulose skeleton The graft copolymer of the present invention can be referred to as a cellulose graft copolymer. As used herein, "cellulose graft copolymer" can refer to a graft copolymer in which the main chain polymer is cellulose (see, for example, Kang, H., et al., 2015. Polymer, 70, pp. A1-A16).

[0040] Cellulose is a polysaccharide consisting of linear chains of hundreds to thousands of β(1→4) linked D-glucose units and can have the molecular formula:

[0041] [ka]

[0042] Any suitable source of cellulose can be used in the present invention (see, for example, Lavanya, DKPK, et al., 2011. International Journal of Drug Formulation and Research, 2(6), pp. 19-38). The main industrial source of cellulose is vascular plants. For example, most cellulose used in paper products comes from wood pulp. The molecular weight of cellulose can depend on its source and extraction conditions for purification.

[0043] The cellulose graft copolymers of the present invention may be in the form of cellulose fibers, which are generally extracted from plants, seeds or trees, and such fibers contain not only cellulose molecules but also hemicellulose and lignin.

[0044] Polypeptide Branching In the graft copolymers of the present invention, the graft polymer branches are polypeptides.

[0045] As used herein, "polypeptide" can refer to multiple amino acid residues linked by peptide bonds. Preferably, the polypeptide is at least about 10 amino acids, at least about 15 amino acids, or at least about 20 amino acids in length. Any suitable polypeptide can be grafted onto the scaffold. Preferably, the polypeptide is a water-soluble polypeptide. Preferably, the polypeptide is a fibrous polypeptide or a globular polypeptide. Suitable fibrous polypeptides can include collagen. Suitable globular polypeptides can include any type of albumin or globulin. Suitable polypeptides include collagen, ovalbumin, serum albumin, lactoglobulin, or hydrolyzed forms thereof. In some embodiments, the polypeptide is selected from one or more of collagen, ovalbumin, serum albumin, lactoglobulin, or hydrolyzed forms thereof. In a preferred embodiment, the polypeptide is collagen or a hydrolyzed form thereof.

[0046] Collagen is composed of a right-handed bundle of three parallel left-handed polyproline type II (PPII) helices. The tight packing of the PPII helices within this triple helix requires that every third residue be Gly, resulting in a repeat of the XaaYaaGly sequence (where Xaa and Yaa can be any amino acid residue). This repeat occurs in all types of collagen. The amino acids at the Xaa and Yaa positions in collagen are most often (2S)-proline (Pro, 28%) and (2S,4R)-4-hydroxyproline (Hyp, 38%), respectively. ProHypGly is the most common triplet in collagen (10.5%) (see, e.g., Shoulders, MD and Raines, RT, 2009, Annual Review of Biochemistry, 78, p. 929).

[0047] Any suitable source of collagen can be used in the present invention (see, for example, Silvipriya, KS, et al., 2015. Journal of Applied Pharmaceutical Science, 5(3), pp. 123-127). Animal sources include bovine, porcine, and fish. Collagen is primarily found in connective tissues, such as cartilage, bone, tendon, ligament, and skin.

[0048] Any suitable form of hydrolyzed collagen can be used in the present invention (see, for example, Mariod, AA and Fadul, H., 2013. Acta Scientiarum Polonorum Technologia Alimentaria, 12(2), pp. 135-147). Suitable forms of hydrolyzed collagen include gelatin, which is obtained by thermal denaturation of collagen. In some embodiments, the polypeptide branch is gelatin.

[0049] Linker The polypeptide branches may be grafted to the backbone by any suitable coupling chemistry. Preferably, the polypeptide branches are attached to the backbone by a linker. Preferably, the graft copolymer comprises the formula:

[0050] [ka]

[0051] The linker can be any suitable linker, for example, any linker described herein. Preferably, the linker is an aliphatic group (e.g., having 1 to 8 carbon atoms) optionally substituted with one or more functional groups (e.g., one or more alcohol, carboxyl, and / or amide groups), optionally attached to one or more polypeptides, and / or optionally crosslinked to one or more other backbones.

[0052] Preferably, the linker is attached to the backbone by an ester bond (e.g., at the cellulose 6-hydroxyl group) and to the polypeptide by a peptide bond (e.g., at the polypeptide N-terminus). The linker may be derived from a molecule containing two or more carboxylic acid groups (or anhydrides thereof). In this context, "derived from" may mean that before the grafting reaction, the linker is a molecule containing two or more carboxylic acid groups (or anhydrides thereof), but after the grafting reaction, one carboxylic acid group forms an ester bond (e.g., at the cellulose 6-hydroxyl group) and one carboxylic acid group forms a peptide bond (e.g., at the polypeptide N-terminus). Preferably, the graft copolymer comprises the following formula:

[0053] [ka]

[0054] A linker may be an aliphatic group (e.g., having 1 to 8 carbon atoms) optionally substituted with one or more functional groups (e.g., one or more alcohol groups), optionally attached to one or more polypeptides, and / or optionally crosslinked to one or more other backbones.

[0055] Molecules containing two or more carboxylic acid groups (or anhydrides thereof) include polycarboxylic acids or anhydrides thereof. As used herein, "polycarboxylic acid" may refer to an organic compound containing two or more carboxyl groups (-COOH), including dicarboxylic acids and tricarboxylic acids. As used herein, "acid anhydride" may refer to an organic compound having two acyl groups bonded to the same oxygen atom, and "carboxylic acid anhydride" may refer to an acid anhydride whose parent acid is a carboxylic acid.

[0056] In some embodiments, the linker is derived from a dicarboxylic acid or anhydride thereof. In some embodiments, the linker is derived from a dicarboxylic acid anhydride. Suitable dicarboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, acetylenedicarboxylic acid, glutaconic acid, muconic acid, glutic acid, citraconic acid, mesaconic acid, and itaconic acid. Suitable dicarboxylic acid anhydrides include malonic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, pimelic anhydride, suberic anhydride, azelaic anhydride, sebacic anhydride, maleic anhydride, glutaconic anhydride, muconic anhydride, citraconic anhydride, mesaconic anhydride, and itaconic anhydride. Preferably, the graft copolymer comprises the formula:

[0057] [ka]

[0058] R may be an aliphatic group (e.g., having 1 to 8 carbon atoms) optionally substituted with one or more functional groups (e.g., one or more alcohol groups). In some embodiments, R is an aliphatic group having 1 to 8 carbon atoms. In some embodiments, R is an aliphatic group having 2 to 4 carbon atoms. In some embodiments, R is an aliphatic group having 2 to 3 carbon atoms.

[0059] In some embodiments, the linker is derived from succinic acid or its anhydride. In some embodiments, the linker is derived from succinic anhydride. Suitably, the graft copolymer comprises the formula:

[0060] [ka]

[0061] In some embodiments, the linker is derived from a tricarboxylic acid or anhydride thereof. In some embodiments, the linker is derived from a tricarboxylic acid. Suitable tricarboxylic acids include citric acid, isocitric acid, cis-aconitic acid, trans-aconitic acid, and tricarballylic acid. Suitable tricarboxylic acid anhydrides include citric acid anhydride, citric acid 1,5-anhydride, isocitric acid anhydride, cis-aconitic acid anhydride, trans-aconitic acid anhydride, and tricarballylic acid anhydride.

[0062] Compared to dicarboxylic acids or their anhydrides, tricarboxylic acids or their anhydrides may have the advantage of allowing for further branching, for example, by (i) linking two polypeptides and / or (ii) cross-linking the backbone to another. Suitably, the graft copolymer comprises the formula:

[0063] [ka]

[0064] R may be an aliphatic group (e.g., having 1 to 8 carbon atoms) optionally substituted with one or more functional groups (e.g., one or more alcohol groups). In some embodiments, R is an aliphatic group having 1 to 8 carbon atoms optionally substituted with one or more alcohol groups. In some embodiments, R is an aliphatic group having 3 to 5 carbon atoms optionally substituted with one or more alcohol groups. In some embodiments, R is an aliphatic group having 3 to 4 carbon atoms optionally substituted with one or more alcohol groups. In some embodiments, R is an aliphatic group substituted with one alcohol group.

[0065] In some embodiments, the linker is derived from citric acid or its anhydride. In some embodiments, the linker is derived from citric acid. Suitably, the graft copolymer comprises the formula:

[0066] [ka]

[0067] Method for grafting polypeptide onto cellulose In one aspect, the invention provides a method for grafting a polypeptide onto a cellulosic backbone.

[0068] The "grafting onto" or "grafting onto" method can involve the use of a backbone chain with functional groups randomly distributed along the chain. The formation of the graft copolymer results from a coupling reaction between the functionalized backbone and the reactive end groups of the branches. These coupling reactions can be made possible by chemically modifying the backbone, thereby functionalizing the backbone.

[0069] The method of the present invention may comprise the steps of (a) functionalizing cellulose and (b) grafting a polypeptide onto the functionalized cellulose. Any suitable reaction conditions may be used to carry out steps (a) and (b). Suitable reaction conditions are described below.

[0070] Step (a): Backbone functionalization Any suitable method can be used to functionalize the backbone. For example, step (a) may include functionalizing the backbone with a linker molecule to provide a functionalized backbone. In one aspect, the present invention provides a functionalized backbone obtained or obtainable by step (a). In some embodiments, the functionalized backbone comprises a carboxylic acid functional group.

[0071] The linker molecule can be any suitable linker molecule, for example, any linker molecule described herein. The linker molecule can include two or more carboxylic acid groups (or anhydrides thereof). Preferably, the functionalized backbone includes the formula:

[0072] [ka]

[0073] The linker may be an aliphatic group (e.g., having 1 to 8 carbon atoms) optionally substituted with one or more functional groups (e.g., one or more alcohol groups) and optionally crosslinked to one or more other backbones.

[0074] In some embodiments, the linker molecule is a dicarboxylic acid or anhydride thereof. In some embodiments, the linker molecule is a dicarboxylic acid anhydride. Suitable dicarboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, acetylenedicarboxylic acid, glutaconic acid, muconic acid, glutic acid, citraconic acid, mesaconic acid, and itaconic acid. Suitable dicarboxylic acid anhydrides include malonic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, pimelic anhydride, suberic anhydride, azelaic anhydride, sebacic anhydride, maleic anhydride, glutaconic anhydride, muconic anhydride, citraconic anhydride, mesaconic anhydride, and itaconic anhydride. Preferably, the functionalized backbone comprises the formula:

[0075] [ka]

[0076] R may be an aliphatic group (e.g., having 1 to 8 carbon atoms) optionally substituted with one or more functional groups (e.g., one or more alcohol groups). In some embodiments, R is an aliphatic group having 1 to 8 carbon atoms. In some embodiments, R is an aliphatic group having 2 to 4 carbon atoms. In some embodiments, R is an aliphatic group having 2 to 3 carbon atoms.

[0077] In some embodiments, the linker molecule is succinic acid or anhydride thereof. In some embodiments, the linker molecule is succinic anhydride. Preferably, the functionalized backbone comprises the formula:

[0078] [ka]

[0079] In some embodiments, the linker molecule is a tricarboxylic acid or anhydride thereof. In some embodiments, the linker molecule is a tricarboxylic acid. Suitable tricarboxylic acids include citric acid, isocitric acid, cis-aconitic acid, trans-aconitic acid, and tricarballylic acid. Suitable tricarboxylic acid anhydrides include citric acid anhydride, citric acid 1,5-anhydride, isocitric acid anhydride, cis-aconitic acid anhydride, trans-aconitic acid anhydride, and tricarballylic acid anhydride. Preferably, the functionalized backbone comprises the formula:

[0080] [ka]

[0081] R may be an aliphatic group (e.g., having 1 to 8 carbon atoms) optionally substituted with one or more functional groups (e.g., one or more alcohol groups). In some embodiments, R is an aliphatic group having 1 to 8 carbon atoms optionally substituted with one or more alcohol groups. In some embodiments, R is an aliphatic group having 3 to 5 carbon atoms optionally substituted with one or more alcohol groups. In some embodiments, R is an aliphatic group having 3 to 4 carbon atoms optionally substituted with one or more alcohol groups. In some embodiments, R is an aliphatic group substituted with one alcohol group.

[0082] In some embodiments, the linker molecule is citric acid or anhydride thereof. In some embodiments, the linker molecule is citric acid. Preferably, the functionalized backbone comprises the formula:

[0083] [ka]

[0084] Preferably, the linker molecule is present in the reaction mixture in an amount of at least 0.5 equivalents, at least 1.0 equivalents, or at least 1.5 equivalents. Preferably, the linker molecule is present in the reaction mixture in an amount of 10.0 equivalents or less, 5.0 equivalents or less, or 4.0 equivalents or less. Preferably, the linker molecule is present in the reaction mixture in an amount of 0.5 to 10.0 equivalents, 1.0 to 5.0 equivalents, or 1.5 to 4.0 equivalents.

[0085] The linker molecule can be coupled to the backbone under any suitable reaction conditions. For example, if the reaction is an esterification reaction, the reaction can be carried out in the presence of a catalyst and heat. Preferably, the reaction mixture contains a nucleophilic catalyst, such as 4-dimethylaminopyridine (DMAP). Preferably, the nucleophilic catalyst (e.g., DMAP) can be added in an amount of 0.1 equivalents. Preferably, the reaction can be carried out at 95°C for 24 hours. For example, if the reaction uses a primary alcohol and a dicarboxylic acid, N-hydroxysuccinimide (NHS) or its water-soluble analog, sulfo-NHS, can be included to activate the carboxylic acid group.

[0086] Any suitable method known in the art can be used to follow the progress of the reaction and / or to confirm that a functionalized scaffold has been obtained. Suitably, infrared (IR) spectroscopy, such as Fourier transform infrared (FT-IR) spectroscopy, can be used to confirm that a functionalized scaffold has been obtained. For example, functionalization with a carboxylic acid can be confirmed by the absorption of IR at 1650 cm -1 Alternatively, solid state NMR can be used to confirm that a functionalized scaffold has been obtained.

[0087] Step (b): Grafting of the polypeptide onto the functionalized backbone Any suitable method can be used to graft the polypeptide onto the functionalized backbone. In one aspect, the present invention provides a graft copolymer obtained or obtainable by step (b).

[0088] For example, if the functionalized backbone contains carboxylic acid functional groups, the polypeptide may be grafted onto the functionalized backbone via a carboxyl-reactive crosslinking reaction, such as a carbodiimide crosslinking reaction. Any suitable carbodiimide crosslinker, such as 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDAC) or N,N'-dicyclohexylcarbodiimide (DCC), may be used. EDAC reacts with carboxylic acid groups to form an active O-acylisourea intermediate that is easily displaced by nucleophilic attack from primary amine groups in the reaction mixture. The primary amine forms an amide bond with the original carboxyl group, releasing the EDAC by-product as a soluble urea derivative. Preferably, EDAC is added to the reaction mixture in an amount of 0.5 equivalents.

[0089] Any suitable reaction conditions can be used. For example, N-hydroxysuccinimide (NHS) or its water-soluble analog sulfo-NHS can be included in the carbodiimide coupling reaction to improve efficiency or generate an amine-reactive intermediate. EDAC attaches NHS to the carboxyl to form an NHS ester, which is significantly more stable than the O-acylisourea intermediate, while allowing for efficient conjugation to primary amines. Preferably, NHS can be added to the reaction mixture in an amount of 1.5 equivalents. A base can also be added to the reaction mixture, for example, to deprotonate the carboxylic acid. For example, triethylamine (TEA) can be added to the reaction mixture in an amount of 0.1 equivalents. Preferably, the reaction can be carried out at 95°C for 24 hours.

[0090] Any suitable method known in the art can be used to monitor the progress of the reaction and / or to confirm that a graft copolymer has been obtained. Preferably, infrared (IR) spectroscopy, such as Fourier transform infrared (FT-IR) spectroscopy, can be used to confirm that a graft copolymer has been obtained. For example, grafting with a polypeptide via an amide bond can be confirmed by observing a peak at 1650 cm in the IR spectrum. -1 , 1550cm -1 and 1420 cm -1The presence of amide stretches in the graft copolymer can be confirmed by monitoring the appearance of amide stretches in the graft copolymer. Alternatively, solid-state NMR can be used to confirm that a graft copolymer has been obtained. Alternatively, the Kjeldahl method can be used to confirm that the graft copolymer contains polypeptide branches (see, for example, Bradstreet, RB, 1954, Analytical Chemistry, 26(1), pp. 185-187).

[0091] Cellulose-based substrate In one aspect, the present invention provides a cellulosic substrate comprising or consisting of the graft copolymer of the present invention, or the graft copolymer obtained or obtainable by the process of the present invention.

[0092] As used herein, "cellulosic substrate" can include any base material that contains cellulose, such as paper, paperboard, cardboard, and wood films. The substrate may be used in a converting process, such as printing or coating, and generally refers to a base material onto which, for example, an image is printed. The cellulosic substrate can be used to manufacture an article or substance, such as a packaging material. In some embodiments, the cellulosic substrate is a paper substrate, a paperboard substrate, or a cardboard substrate.

[0093] Suitably, the cellulosic substrate comprises the graft copolymer of the present invention, or the graft copolymer obtained or obtainable by the process of the present invention, in an amount of at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% by weight.

[0094] packaging material In one aspect, the present invention provides a packaging material comprising the graft copolymer of the present invention, the graft copolymer obtained or obtainable by the process of the present invention, or the cellulosic substrate of the present invention.

[0095] The packaging material may comprise at least one paper layer comprising or consisting of the graft copolymer of the present invention, the graft copolymer obtained or obtainable by the method of the present invention, or the cellulosic substrate of the present invention.

[0096] As used herein, "packaging material" may refer to any article or substance that is intended to come into contact with, or that may come into contact with, an edible product for human or animal consumption, and includes containers, such as cartons, boxes, and cases, or wrapping and covering materials, such as paper and wax paper.

[0097] The present invention further relates to a three-dimensional sealed packaging article made from the packaging material described herein (e.g., the metallized paper-based multilayer packaging material described herein), obtained by shaping the packaging material, then filling it with an edible product for human or animal consumption, and then sealing it.

[0098] The present invention further relates to the use of packaging materials described herein (e.g., metallized paper-based multi-layer packaging materials described herein) to package edible products for human or animal consumption.

[0099] The present invention further relates to a packaged edible product comprising a packaging material described herein (e.g., a metallized paper-based multilayer packaging material described herein) filled with a food or edible product for animal consumption. Preferably, the edible product is a powder, gel, or kibble selected from the following list: soluble coffee, nutritional compositions for infant, adult, or elderly consumption, soup, confectionery or candy, chocolate-based products, dry animal food, dairy products.

[0100] Metallized paper-based multilayer packaging material In a preferred embodiment, the packaging material is a metallized paper-based multilayer packaging material. A "metallized paper-based multilayer packaging material" may comprise a paper layer, a pre-metallization coating layer, a metallization layer, and a coating layer that is inner than the metallization layer.

[0101] The paper layer may comprise or consist of the graft copolymer of the present invention, the graft copolymer obtained or obtainable by the method of the present invention, or the cellulosic substrate of the present invention. Preferably, the paper layer has a density of 30 to 120 g / m 2 Suitably, the paper layer comprises the graft copolymer of the present invention, or the graft copolymer obtained or obtainable by the process of the present invention, in an amount of at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% by weight.

[0102] The coating layer that is outer than the metal coating may comprise or consist of at least one organic barrier layer of a polymer selected from the list of polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butenediol vinyl alcohol copolymer (BVOH), or a combination thereof. The at least one organic barrier layer has a thickness of 0.5 to 20 g / m 2 Amount of, preferably 1 to 10 g / m 2 More preferably, the amount is 2 to 8 g / m 2 may be present in an amount of

[0103] The metallization layer may comprise or consist of at least one inorganic barrier layer selected from the list of metals, metalloids, or combinations thereof. The metallization layer may have a thickness of 1 to 100 nm. In a preferred embodiment, the at least one inorganic barrier layer comprises a metal or metalloid selected from the list of aluminum, aluminum oxide (AlOx), or silicon oxide (SiOx). The metal and / or metalloid may be deposited by either vacuum evaporation or transfer metallization. In a particularly preferred embodiment, the at least one inorganic barrier layer is a vacuum-deposited layer of aluminum.

[0104] The coating layer that is inner than the metal coating may comprise or consist of at least one organic heat-seal layer comprising a heat-sealable polymer. The at least one organic heat-seal layer has a density of 2 to 20 g / m 2 Amount of 4 to 9 g / m 2 may be present in an amount of

[0105] Each of the organic layers is preferably deposited onto the adjacent layer either by aqueous dispersion or by aqueous solution deposition.

[0106] In a preferred embodiment, the metallized paper-based multilayer packaging material comprises, from the outside to the inside, 30~120g / m 2 a paper layer having a basis weight in the range of At least one organic barrier layer of a polymer selected from the list of polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butenediol vinyl alcohol copolymer (BVOH), or a combination thereof, having a density of 0.5 to 20 g / m 2 Amount of, preferably 1 to 10 g / m 2 More preferably, the amount is 2 to 8 g / m 2 an organic barrier layer in an amount of at least one inorganic barrier layer selected from the list of metals, metalloids, or combinations thereof, having a thickness in the range of 1 to 100 nm; At least one organic heat-sealable layer comprising a heat-sealable polymer, having a density of 2 to 20 g / m 2 An amount falling within the range of 4 to 9 g / m 2 an organic heat seal layer applied in an amount falling within the range of Equipped with.

[0107] In all of the embodiments of the present invention described herein, the multilayer structure may include other additional and optional layers not described in full detail. Such layers may include, for example, a printing layer on the outer surface of the paper layer, and optionally, a protective layer deposited on the outside of the printing layer, thus constituting the outermost layer of the entire structure. The printing layer and optional protective layer are well known to those skilled in the art and will not be described in further detail.

[0108] In some embodiments, the paper layer is covered on its outer surface with an ink layer. The ink layer has a density of 0.5 to 5 g / m 2 In a preferred embodiment, the ink layer is selected from the list of water-based inks, solvent-free inks, or a combination thereof.

[0109] More preferably, the outer surface of the paper layer or ink layer is covered with an outermost layer of overprint varnish (OPV). The OPV layer has a thickness of 0.5 to 10 g / m 2 The optional OPV layer, if present, may also contribute to improving the barrier paper's resistance to hygroexpansive strain, particularly by improving the barrier to moisture (water vapor transmission rate or "WVTR") under humid conditions. In an advantageous embodiment, the outermost overprint varnish layer is a styrene acrylic varnish.

[0110] The metallized paper-based multi-layer packaging material according to the present invention advantageously achieves the following oxygen and moisture barrier properties: 2 / day (measured at 23°C and 85% relative humidity), and / or a water vapor transmission rate (WVTR) of less than 0.1 cm 3 / m 2 Oxygen transmission rate (OTR) of less than / day bar (measured at 23°C and 50% RH). These values ​​are measured according to flexibility testing standard ASTM F392 or equivalent after subjecting the sample to an in-plane tensile pre-strain of up to 2% and after subjecting the sample to three cycles in a Gelboflex testing apparatus.

[0111] The metallized paper-based multilayer packaging material according to the present invention preferably has a strain at break under in-plane tensile load of up to 5% in the machine direction of the paper and up to 15% in the cross-machine direction, with the overall paper structure having a strain at break of 2.5% in the machine direction and 9% in the cross-machine direction, providing high mechanical recovery.

[0112] The multi-layer structure according to the present invention is preferably designed to comply with most local or national paper recycling regulations and be suitable for recycling in standard recycled paper stream processes as well. Recyclability in paper stream processes is achieved by the multi-layer structure according to the present invention, wherein: The fiber content is significant compared to all the raw materials in the structure (the definition of recyclability in paper recycling processes varies depending on national legislation, but on average a material must contain at least 80% fiber to be accepted in paper-specific recycling processes), and The inorganic layer is ultrathin (i.e., a few nanometers, typically 1-100 nm) and consists of a few atoms in thickness. All organic polymer layers are deposited by aqueous dispersion or aqueous solution deposition coating, which means that the layers thus obtained are sufficiently thin relative to the thickness of the paper to achieve a very high paper content throughout the structure, making the entire structure compatible with the paper recycling process described herein; The organic barrier layer preferably comprises a water-soluble polymer (i.e., PVOH, EVOH and / or BVOH), which makes it easier to separate the fibers from the rest of the material of the structure, especially from the cellulosic contents.

[0113] A first embodiment of the present invention is shown in Figure 5. In this embodiment, a multi-layer structure 1 has, from its outer side (i.e., the side of the material facing the outside of a package made from the structure) to its inner side (i.e., the side that comes into contact with a product packaged in a package made from the structure), 1. A method for producing a cellulose-based substrate comprising: a graft copolymer of the present invention, a graft copolymer obtained or obtainable by the process of the present invention, or a cellulosic substrate of the present invention, optionally having a basis weight of 62 g / m 2 2, a very smooth paper layer; Mainly provides gas (especially oxygen) barrier properties, optionally 3 g / m 2 a first organic polyvinyl alcohol-based (PVOH) coating layer 3 on the outer side of the metal coating, applied as an aqueous solution of an inorganic vacuum deposited layer 4 of aluminum, optionally having a thickness of 40 nm, which primarily provides water vapor barrier properties; and 5 g / m 2 a second organic coating layer 5 of a methacrylic acid ionomer based coating applied as an aqueous dispersion of Equipped with.

[0114] In this first embodiment, the deposition techniques for the first and second organic layers as described above allow for improved recyclability of said layers in the paper recycling process. The structure 1 of this first embodiment has an oxygen transmission rate (OTR) value of 0.5 cm, measured at 23°C and 50% relative humidity (RH). 3 / m 2 / day and a water vapor transmission rate (WVTR) of 0.5 g / m2 measured at 23°C and 85% RH 2 / day or less, high moisture barrier property and gas barrier property can be achieved.

[0115] The strain at break for the entire Structure 1 can be measured as 2.5% in the machine direction and 9% in the cross-machine direction. These values ​​provide excellent recovery properties that allow the aluminum layer to be protected during processing of the structure in conventional packaging forming processes. When manufacturing packages from the material, the aluminum layer does not crack while bending, stretching, and / or sealing the material, resulting in comparable OTR and WVTR barrier levels being maintained before and after packages are formed from the multilayer structure material.

[0116] Figure 6 shows a similar structure to that described above in relation to Figure 5. However, in this second exemplary embodiment of the invention, the outer surface of the paper layer 2 is made up of, in order from the outer surface of the packaging material to the inside: Optionally 1g / m 2 an outermost layer 7 of acrylic overprint varnish applied as an aqueous dispersion of Optionally 1g / m 2 water-based ink 6, applied as an aqueous dispersion of The water-based ink layer 6 is located between the outermost overprint varnish layer 7 and the paper layer 2.

[0117] The remaining layers of Structure 1 remain similar to the structure described with reference to FIG. 5, i.e.: 1. A method for producing a cellulose-based substrate comprising: a graft copolymer of the present invention, a graft copolymer obtained or obtainable by the process of the present invention, or a cellulosic substrate of the present invention, optionally having a basis weight of 62 g / m 2 2, a very smooth paper layer; Mainly provides gas (especially oxygen) barrier properties, optionally 3g / m 2 a first organic polyvinyl alcohol (PVOH) coating layer 3 applied as an aqueous solution of an inorganic vacuum deposited layer 4 of aluminum, optionally having a thickness of 40 nm, which primarily provides water vapor barrier properties; and Optionally 5g / m 2 and a second organic coating layer 5 of a methacrylic acid ionomer based coating applied as an aqueous dispersion of 1000 ppm by weight.

[0118] Structures corresponding to the above embodiments meet the requirements for recyclability of such materials or packaging made from such materials in standard paper recycling mill conditions.

[0119] Method for manufacturing metallized paper-based multilayer packaging material Generally, as used herein, "extrusion coating" refers to a method of applying a layer of polymer by using an extruder to force a molten thermoplastic resin (e.g., polyethylene) through a horizontal slot die onto a moving web of substrate (e.g., paper). The product is a permanently coated web structure.

[0120] "Extrusion lamination" refers to a process akin to extrusion coating in which a polymer resin is extruded between two substrates (eg, a layer of paper and another layer of polymer film) to act as a binder.

[0121] "Adhesive lamination" refers to a process in which one paper material is coated with an adhesive and laminated to a second paper or paperboard material. In the lamination process, two thick layers of material are combined by either extrusion lamination or adhesive lamination, resulting in a thickness of each layer that is much greater than that achieved by dispersion coating.

[0122] "Dispersion coating" refers to a coating technique in which an aqueous dispersion of fine polymer particles or a polymer solution is applied directly to the surface of paper or paperboard to form a solid, nonporous film after drying. Dispersion coating can be performed by gravure, flexogravure, rod, blade, slot die, curtain air knife, roll coating, or any other known paper coating method. Because the polymer is mixed into an aqueous solution, dispersion coating can produce much thinner layers than extrusion lamination and / or adhesive lamination. This offers advantages in terms of polymer usage, its barrier performance, and the recyclability of the resulting paper structure. The goal of dispersion coating is to provide a barrier layer against water, water vapor, grease, oil, gas, etc., using an environmentally friendly coating. Another goal is to prepare the surface of the paper material for vacuum deposition processes.

[0123] Example The present invention will now be further described by way of examples, which are meant to aid those skilled in the art in practicing the invention and are not intended to limit the scope of the invention in any way.

[0124] Example 1: Grafting of collagen onto cellulose via a succinic acid linker The grafting of collagen is carried out via a two-step reaction (see reaction scheme in Figure 1).

[0125] The first step involves functionalizing cellulose with a carboxylic acid spacer by grafting succinic anhydride. 4-Dimethylaminopyridine (DMAP) is used to partially deprotonate the cellulose hydroxyl groups, which then attack the carbonyl group of the anhydride, opening the ring and releasing the carboxylic acid. IR spectra were taken and showed a peak at 1650 cm. -1 The first stage of the reaction can be monitored by tracking the increase in the carboxylic acid signal in the reaction mixture. The reaction is left overnight for completion. The resulting pulp is filtered and washed thoroughly with water until a neutral pH is obtained.

[0126] The carboxylic acid is then activated using a carbodiimide crosslinker, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC), and N-hydroxysuccinimide (NHS), to allow grafting at the N-terminus of collagen. The collagen grafting is observed in the IR spectrum at 1650 cm. -1 , 1550cm -1 and 1420 cm -1 The reaction is monitored by observing the appearance of an amide bond stretch in the reaction mixture. The reaction is left overnight, after which the pulp is filtered and washed thoroughly with deionized water.

[0127] Handmade papers were formed from the recovered grafted cellulose fibers. As observed in Figure 2A, applying a water droplet to small pieces of handmade paper with and without grafted collagen revealed a much larger contact angle of the droplet in the presence of grafted collagen. This suggests that the hydrophobicity of the handmade paper was increased compared to that without grafted collagen and that collagen buffers water absorption by cellulose, thereby creating a more hydrophobic surface. Monitoring the contact angle over time revealed that in the presence of collagen, water droplet adsorption (as observed by a decrease in contact angle over time) was slower compared to reference cellulose (see Figure 2B). This was confirmed when different volumes of water were applied (see Figure 2C). Systematically, in the presence of grafted collagen, the contact slope as a function of time was smaller, suggesting less water adsorption, and therefore suggesting that the increased hydrophobicity of the fibers was imparted by water adsorption by collagen, rather than cellulose.

[0128] The grafting of collagen onto cellulose was further evidenced by EDX measurements (see Figure 3A). This revealed a higher nitrogen content compared to the cellulose reference, confirming the presence of collagen protein. Addition of a water droplet to the sample resulted in swelling of the sample (see Figure 3B-C). As can be seen in the SEM images, a swelling effect was observed on the surface of the sample after wetting. Furthermore, when EDX was performed on the transparent fibers and background, a higher nitrogen content was observed, suggesting that the collagen swelled, resulting in an increase in nitrogen content.

[0129] Example 2: Grafting of collagen onto cellulose via a citrate linker Grafting of collagen onto cellulose was also achieved with citric acid (see reaction scheme in Figure 4). Treatment of cellulose with 3 equivalents of citric acid (in the presence of DMAP) resulted in the formation of a 1650 cm -1An increase in the carboxylic acid signal at 1000 kJ / cm was monitored by FT-IR, suggesting bond formation. Further reaction with EDAC and NHS to activate the carboxylic acid, followed by the addition of collagen, resulted in an increase in the amide signal in FT-IR, confirming the grafting of collagen onto the newly formed carboxyl functional groups.

[0130] Citric acid-grafted cellulose tended to give more transparent films compared to unmodified cellulose, which may be due to the increased cross-linking between cellulose fibers imparted by citric acid, leading to reduced porosity and reduced light diffraction, resulting in a more translucent appearance.

[0131] Embodiment Various preferred features and embodiments of the present invention will now be described with reference to the following numbered paragraphs.

[0132] 1. Cellulose graft copolymers with polypeptide branches. 2. The cellulose graft copolymer of paragraph 1, wherein the polypeptide is collagen or a hydrolyzed form thereof. 3. The cellulose graft copolymer of paragraph 1 or 2, wherein the polypeptide branches are attached to the cellulose by linkers, and optionally the cellulose graft copolymer comprises the formula: [ka] 4. The cellulose graft copolymer of any one of paragraphs 1 to 3, wherein the polypeptide branches are attached to the cellulose by polycarboxylic acids or anhydrides thereof, and optionally the cellulose graft copolymer comprises the formula: [ka] 5. The cellulose graft copolymer of any one of paragraphs 1 to 4, wherein the polypeptide branches are attached to the cellulose by tricarboxylic acids or anhydrides thereof, and optionally the polypeptide branches are attached to the cellulose by tricarboxylic acids selected from one or more of citric acid, isocitric acid, aconitic acid, or tricarballylic acid, or anhydrides thereof. 6. The cellulose graft copolymer of paragraph 5, wherein the polypeptide branches are attached to the cellulose by citric acid or anhydride thereof, preferably the polypeptide branches are attached to the cellulose by citric acid. 7. The cellulose graft copolymer of any one of paragraphs 1 to 4, wherein the polypeptide branches are attached to the cellulose by dicarboxylic acids or anhydrides thereof, and optionally the polypeptide branches are attached to the cellulose by dicarboxylic acids selected from one or more of malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid, or anhydrides thereof. 8. The cellulose graft copolymer of paragraph 7, wherein the polypeptide branches are attached to the cellulose by succinic acid or anhydride, preferably the polypeptide branches are attached to the cellulose by succinic anhydride. 9. A method for grafting a polypeptide onto cellulose, comprising the steps of: (a) functionalizing cellulose with a linker molecule to provide a functionalized cellulose; (b) grafting a polypeptide onto the functionalized cellulose to provide a cellulose graft copolymer comprising polypeptide branches; A method comprising: 10. The method of paragraph 9, wherein the polypeptide is collagen or a hydrolyzed form thereof. 11. The method of paragraph 9 or 10, wherein the linker molecule is a polycarboxylic acid or anhydride thereof, and optionally the functionalized cellulose comprises the formula: [ka] 12. The method of any one of paragraphs 9 to 11, wherein the linker molecule is a tricarboxylic acid or an anhydride thereof, optionally wherein the linker molecule is a tricarboxylic acid selected from one or more of citric acid, isocitric acid, aconitic acid, or tricarballylic acid, or anhydrides thereof. 13. The method of paragraph 12, wherein the linker molecule is citric acid or anhydride thereof, preferably the linker molecule is citric acid. 14. The method of any one of paragraphs 9 to 11, wherein the linker molecule is a dicarboxylic acid or an anhydride thereof, optionally wherein the linker molecule is a dicarboxylic acid selected from one or more of malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid, or anhydrides thereof. 15. The method of paragraph 14, wherein the linker molecule is succinic acid or anhydride thereof, preferably the linker molecule is succinic anhydride. 16. The method of any one of paragraphs 11 to 15, wherein the polycarboxylic acid or anhydride thereof is incubated with a nucleophilic catalyst, optionally wherein the nucleophilic catalyst is 4-dimethylaminopyridine (DMAP). 17. The method of any one of paragraphs 11 to 16, wherein polypeptide chains are grafted to the functionalized cellulose by a carbodiimide crosslinking reaction. 18. The method of paragraph 17, wherein the carbodiimide crosslinking agent is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC), and optionally, N-hydroxysuccinimide (NHS) is included in the carbodiimide crosslinking reaction. 19. A cellulose graft copolymer obtained or obtainable by the method described in any of paragraphs 9 to 18. 20. Functionalized cellulose, which is functionalized with a polycarboxylic acid or an anhydride thereof. 21. The functionalized cellulose according to paragraph 20, wherein the functionalized cellulose is functionalized with a tricarboxylic acid or an anhydride thereof, optionally wherein the functionalized cellulose is functionalized with a tricarboxylic acid selected from one or more of citric acid, isocitric acid, aconitic acid, or tricarballylic acid, or anhydrides thereof, preferably wherein the functionalized cellulose is functionalized with citric acid or an anhydride thereof, more preferably wherein the functionalized cellulose is functionalized with citric acid. 22. The functionalized cellulose according to paragraph 20, wherein the functionalized cellulose is functionalized with a dicarboxylic acid or an anhydride thereof, optionally the functionalized cellulose is functionalized with a dicarboxylic acid selected from one or more of malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid, or anhydrides thereof, preferably the functionalized cellulose is functionalized with succinic acid or anhydride thereof, more preferably the functionalized cellulose is functionalized with succinic anhydride. 23. A cellulosic substrate comprising or consisting of the cellulose graft copolymer described in any one of paragraphs 1 to 8 or paragraph 19. 24. The cellulosic substrate of paragraph 23, wherein the cellulosic substrate is a paper substrate, a paperboard substrate, or a cardboard substrate. 25. A packaging material comprising the cellulose graft copolymer of any one of paragraphs 1 to 8 or paragraph 19, or the cellulosic substrate of paragraph 23 or 24. 26. The packaging material is a metallized paper-based multi-layer packaging material, and preferably, the metallized paper-based multi-layer packaging material (1) is, from its outside to its inside, (i) 30 to 120 g / m 2 a paper layer (2) having a basis weight in the range of (ii) at least one organic barrier layer (3) of a polymer selected from the list of polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butenediol vinyl alcohol copolymer (BVOH), or a combination thereof, having a density of 0.5 to 20 g / m2 Amount of, preferably 1 to 10 g / m 2 More preferably, the amount is 2 to 8 g / m 2 an organic barrier layer (3) in an amount of (iii) at least one inorganic barrier layer (4) selected from the list of metals, metalloids, or combinations thereof, having a thickness of 1 to 100 nm; (iv) at least one organic heat-sealable layer (5) comprising a heat-sealable polymer, having a density of 2 to 20 g / m 2 Amount of 4 to 9 g / m 2 an organic heat seal layer (5) applied in an amount of Equipped with the paper layer comprises or consists of the cellulose graft copolymer according to any of paragraphs 1 to 8 or paragraph 19, or the cellulosic substrate according to paragraph 23 or 24, 26. The packaging material of paragraph 25. 27. The metallized paper-based multilayer packaging material (1) according to paragraph 26, wherein the inorganic layer comprises a metal or metalloid selected from the list of aluminum, aluminum oxide (AlOx), or silicon oxide (SiOx), and the metal and / or metalloid is deposited by either vacuum deposition or transfer metallization. 28. The metallized paper-based multi-layer packaging material (1) according to paragraph 26 or 27, wherein the heat seal layer comprises an acrylic or methacrylic polymer grafted with at least one ionomer, preferably a sodium ionomer. 29. The metallized paper-based multi-layer packaging material (1) according to any one of paragraphs 26 to 28, wherein the ionomer-grafted acrylic or methacrylic polymer has a molecular weight of 85 to 90 g / mol. 30. The metallized paper-based multi-layer packaging material (1) of any one of paragraphs 26 to 29, wherein each of the organic layers is deposited on an adjacent layer by either aqueous dispersion or aqueous solution deposition. 31. The metallized paper-based multilayer packaging material (1) according to any one of paragraphs 26 to 30, wherein the paper layer (2) is covered on its outer surface with an ink layer (6). 32. The metallized paper-based multi-layer packaging material (1) according to paragraph 31, wherein the ink layer is selected from the list of water-based ink, solvent-free ink, or a combination thereof. 33. The metallized paper-based multi-layer packaging material (1) according to paragraph 31 or 32, wherein the paper layer or the ink layer is covered on its outer surface by an outermost layer (7) of overprint varnish (OPV). 34. The metallized paper-based multi-layer packaging material (1) according to paragraph 33, wherein the outermost overprint varnish layer (7) is a styrene acrylic varnish. 35. The packaging material has a density of 0.5 g / m 2 / day (measured at 23°C and 85% relative humidity), and / or a water vapor transmission rate (WVTR) of less than 0.1 cm 3 / m 2 35. The metallized paper-based multilayer packaging material (1) of any of paragraphs 26 to 34, having an oxygen transmission rate (OTR) of less than 1 / day bar (measured at 23°C and 50% RH). 36. The metallized paper-based multilayer packaging material of any one of paragraphs 26 to 35, wherein the packaging material has a strain at break under an in-plane tensile load of up to 5% in the machine direction of the paper and up to 15% in the cross-machine direction. 37. A three-dimensional sealed packaging article made of a packaging material according to any of paragraphs 25 to 36, obtained by shaping the packaging material, filling it with an edible product for human or animal consumption, and then sealing it. 38. Use of a cellulose graft copolymer according to any one of paragraphs 1 to 8 or paragraph 19, use of a cellulosic substrate according to paragraph 23 or 24, or use of a packaging material according to any one of paragraphs 25 to 36 for packaging an edible product for human or animal consumption. 39. A packaged edible product comprising the cellulose graft copolymer of any one of paragraphs 1 to 7 or paragraph 19, the cellulosic substrate of paragraph 23 or 24, or the packaging material of any one of paragraphs 25 to 36, filled with an edible product for human or animal consumption.

Claims

1. A cellulosic substrate comprising or consisting of a cellulose graft copolymer comprising polypeptide branches.

2. 10. The cellulosic-based substrate of claim 1, wherein the polypeptide is collagen or a hydrolyzed form thereof.

3. 3. The cellulosic substrate of claim 1 or 2, wherein the polypeptide branches are attached to the cellulose by linkers, and optionally the cellulose graft copolymer comprises the formula: 【Chemistry 1】

4. 4. The cellulosic substrate of any one of claims 1 to 3, wherein the polypeptide branches are attached to the cellulose by polycarboxylic acids or anhydrides thereof, and optionally the cellulose graft copolymer comprises the formula: 【Chemistry 2】

5. the polypeptide branch is (a) a tricarboxylic acid or anhydride thereof, optionally selected from one or more of citric acid, isocitric acid, aconitic acid, or tricarballylic acid, or anhydrides thereof; preferably, the tricarboxylic acid or anhydride thereof is citric acid or anhydride; more preferably, the tricarboxylic acid or anhydride is citric acid; a tricarboxylic acid or anhydride thereof, or (b) a dicarboxylic acid or anhydride thereof, optionally wherein the dicarboxylic acid or anhydride thereof is selected from one or more of malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or sebacic acid, or anhydrides thereof; preferably, the dicarboxylic acid or anhydride thereof is succinic acid or anhydride; more preferably, the dicarboxylic acid or anhydride thereof is succinic anhydride; dicarboxylic acids or their anhydrides, The cellulose-based substrate according to any one of claims 1 to 4, wherein the cellulose is bound to the cellulose by

6. A packaging material comprising the cellulosic substrate according to any one of claims 1 to 5.

7. The packaging material is a metallized paper-based multilayer packaging material (1), and from the outside to the inside, (i) 30-120g / m ２ A paper layer (2) having a basis weight in the range of 1 to 5, and comprising or consisting of the cellulose-based substrate according to any one of claims 1 to 5; (ii) at least one organic barrier layer (3) of a polymer selected from the list of polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), butenediol vinyl alcohol copolymer (BVOH), or a combination thereof, having a density of 0.5 to 20 g / m ２ an organic barrier layer (3) in an amount of (iii) at least one inorganic barrier layer (4) selected from the list of metals, metalloids, or combinations thereof, having a thickness of 1 to 100 nm; (iv) at least one organic heat-seal layer (5) comprising a heat-sealable polymer, having a density of 2 to 20 g / m ２ an organic heat seal layer (5) applied in an amount included in the amount of 7. The packaging material according to claim 6, which is a metallized paper-based multilayer packaging material (1).

8. 8. The metallized paper-based multilayer packaging material (1) of claim 7, wherein the inorganic barrier layer comprises a metal or metalloid selected in the list of aluminum, aluminum oxide (AlOx), or silicon oxide (SiOx), and wherein the metal and / or metalloid is deposited by either vacuum deposition or transfer metallization.

9. 9. The metallized paper-based multilayer packaging material (1) according to claim 7 or 8, wherein the organic heat-seal layer comprises an acrylic or methacrylic polymer grafted with at least one ionomer, preferably a sodium ionomer, and optionally the acrylic or methacrylic polymer grafted with an ionomer has a molecular weight of 85 to 90 g / mol.

10. The metallized paper-based multi-layer packaging material (1) according to any one of claims 7 to 9, wherein each of the organic layers is deposited on the adjacent layer by either aqueous dispersion or aqueous solution deposition.

11. 11. The metallized paper-based multilayer packaging material (1) according to any one of claims 7 to 10, wherein the paper layer (2) is covered on its outer surface with an ink layer (6), preferably the ink layer is selected from the list of water-based ink, solvent-free ink, or a combination thereof, and optionally the paper layer or the ink layer is covered on its outer surface with an outermost layer (7) of overprint varnish (OPV), preferably the outermost overprint varnish layer (7) is a styrene acrylic varnish.

12. (a) 0.5 g / m ２ / day (measured at 23°C and 85% relative humidity), and / or ３ / m ２ / day bar (measured at 23°C and 50% RH), and / or (b) a strain at break under in-plane tensile load of at most 5% in the machine direction and at most 15% in the cross-machine direction of the paper; The metallized paper-based multilayer packaging material (1) according to any one of claims 7 to 11,

13. A three-dimensional sealed packaging article made of the packaging material according to any one of claims 6 to 12, obtained by shaping said packaging material, filling it with an edible product for human or animal consumption and then sealing it.

14. Use of a cellulosic substrate according to any one of claims 1 to 5 or a packaging material according to any one of claims 6 to 12 for packaging an edible product for human or animal consumption.

15. 13. A packaged edible product comprising the cellulosic substrate of any one of claims 1 to 5 or the packaging material of any one of claims 6 to 12 filled with an edible product for human or animal consumption.

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