compostable packaging materials

Abstract

The present disclosure relates to coated paper. The coated paper comprises a cellulose layer and at least two coatings on one side of the paper. The first coating applied to the paper is a barrier coating that can be made from plant- or animal-derived components, and is preferably water-soluble or water-dispersible, more preferably water-soluble. Meanwhile, the second coating can be a heat-sealable coating. The coated paper is particularly suitable for the production of packages.

Description

[Background technology]

[0001] Most flexible packaging materials used in the manufacture of flexible packaging on the market are made from polymers derived from fossil fuels. These materials include, for example, multilayer films containing polyethylene terephthalate polymers and / or polyethylene polymers. While these films have excellent barrier properties and are heat-sealable, they are not sustainable or environmentally friendly. These films and the packaging made from them contain disposable plastics that are used only once and then discarded. While some disposable plastics can be recycled, many decompose very slowly and end up in landfills.

[0002] In light of the above, those skilled in the art have attempted to replace fossil fuel-derived plastic films with paper materials. For example, paper products are produced from sustainable resources, are biodegradable, and are compostable. However, paper has various drawbacks and shortcomings when used as a packaging material. For example, paper is prone to tearing, is not waterproof, and does not have heat-sealing properties.

[0003] WO 2022 / 243445, entitled "Coated Paper for Use as Packaging Material," incorporated herein by reference, discloses a heat-sealable coated paper comprising a cellulose layer and a coating applied to at least one side of the cellulose layer. The coating comprises a wax and a polymer selected from polyester, polysaccharide, polysaccharide ester, polysaccharide ether, or polysaccharide ether ester. While WO '445 provided a significant advance in the art, there is room for further improvement. In particular, there is a need for heat-sealable coated paper with improved barrier properties. For example, there is a need for coated paper with relatively low water vapor and oxygen transmission rates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 243445 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a coated paper suitable as a packaging material that not only has excellent barrier properties, such as low water vapor transmission rate and low oxygen transmission rate, but also has excellent heat-sealing properties. In one aspect, the coated paper can be fully biodegradable and / or compostable, preferably home compostable. For example, the coated paper can be formulated to pass the composting test EN 13432:2001. The coated paper of the present disclosure is not only sustainable and environmentally friendly, but also has excellent mechanical properties, easy processing, and excellent barrier properties. [Means for solving the problem]

[0006] In one embodiment, the coated paper comprises a cellulose layer having a first surface and a second, opposing surface. A barrier coating is applied to the first surface of the cellulose layer. The barrier coating comprises a plant- or animal-derived component and is preferably water-soluble or water-dispersible, more preferably water-soluble. A heat-sealable coating is applied over the barrier coating. The heat-sealable coating comprises a wax.

[0007] The combination of the barrier coating and the heat-sealable coating allows the coated paper to have not only heat-sealability but also excellent barrier properties. For example, the coated paper has a weight of about 10 g / m 2 / 24 hours or less, preferably about 9 g / m 2 / 24 hours or less, more preferably about 8 g / m 2 / 24 hours or less, even more preferably about 7 g / m 2 / 24 hours or less, and even more preferably about 6 g / m 2 / 24 hours, and even more preferably about 5 g / m 2 / 24 hours or less, and even more preferably about 4 g / m 2 / 24 hours or less, and even more preferably about 3 g / m 2 / 24 hours or less, and even more preferably about 2 g / m 2 / 24 hours or less, most preferably about 1 g / m 2 The coated paper 10 can also exhibit excellent oxygen barrier properties. For example, the coated paper can have a moisture vapor transmission rate (MVTR) of less than 1 / 24 hours. 3 / m 2 / less than 24 hours, preferably about 1.75 cm 3 / m 2 / less than 24 hours, more preferably about 1.5 cm 3 / m 2 / less than 24 hours, even more preferably about 1.25 cm 3 / m 2 / less than 24 hours, and even more preferably about 1 cm 3 / m 2 / 24 hours or less, and even more preferably about 0.75 cm 3 / m 2 / less than 24 hours, and even more preferably about 0.5 cm 3 / m 2 / less than 24 hours, most preferably about 0.25 cm 3 / m 2 It can exhibit an oxygen transmission rate (OTR) of less than 24 hours.

[0008] The barrier coating applied to the cellulose layer of the present disclosure significantly improves barrier properties, specifically providing low oxygen permeability, while the heat-sealable coating not only provides heat-sealing properties but also protects the barrier coating from degradation. As noted above, the barrier coating comprises a plant- or animal-derived component, which may optionally be water-soluble or water-dispersible and amorphous. In one aspect, the plant- or animal-derived component may be a milk protein.

[0009] The barrier coating should have a thickness of at least about 2 g / m 2 , e.g., at least about 4 g / m 2 , e.g., at least about 6 g / m 2 , e.g., at least about 8 g / m 2, e.g., at least about 10 g / m 2 , e.g., at least about 12 g / m 2 , e.g., at least about 14 g / m 2 , and about 25 g / m 2 Less than about 20 g / m 2 Less than about 18 g / m 2 The barrier coating can be applied to the cellulose layer to have a basis weight of less than 1000 . In addition to plant- or animal-derived components, the barrier coating can include a variety of other components, including polymers and / or fillers. For example, in one aspect, the barrier coating can also include a polyvinyl alcohol polymer. In yet another embodiment, the barrier coating can include cellulose particles, such as nanocrystalline cellulose.

[0010] In one embodiment, the wax contained in the heat-sealable coating can be a vegetable wax. The vegetable wax can be, for example, candelilla wax, carnauba wax, rice bran wax, soy wax, sugarcane wax, sunflower wax, pea wax, coconut wax, palm wax, or a combination thereof, preferably soy wax. In one embodiment, the heat-sealable coating can further comprise a polymer. The polymer can be a polyester, a polysaccharide, a polysaccharide ester, a polysaccharide ether, a polysaccharide ether ester, a latex polymer, or a combination thereof. In one embodiment, the polymer can be thermoplastic starch. The heat-sealable coating can have a coating density of about 1 g / m. 2 More than, for example, about 2 g / m 2 More than, for example, about 3 g / m 2 More than, for example, about 4 g / m 2 More than, for example, about 5 g / m 2 or more, and generally about 25 g / m 2 Below, for example, about 20 g / m 2 Below, for example, about 18 g / m 2 Below, for example, about 15 g / m 2 Below, for example, about 12 g / m 2 The cellulosic layer can be coated to have the following basis weights:

[0011] In one embodiment, the coated paper includes only two coatings: a barrier coating and a heat-sealable coating. Alternatively, a print-receptive coating can be applied to the second side of the cellulose layer opposite the barrier coating and the heat-sealable coating. In one aspect, the coated paper is configured such that the product does not include a petroleum-based synthetic polymer and / or does not include an adhesive layer between the barrier coating and the first side of the cellulose layer or between the barrier coating and the heat-sealable coating.

[0012] The cellulose layer can be made from any suitable cellulose fiber. For example, the cellulose layer can be made from wood pulp fibers, such as softwood fibers. The cellulose layer can also be made from bast fibers, such as bast pulp fibers. The bast fibers can be hemp fibers, flax fibers, and the like. The cellulose layer can also include hardwood fibers. In one aspect, the cellulose layer can contain wood pulp fibers alone or in combination with bast fibers. The cellulose layer generally has a weight of about 20 g / m 2 ~about 200g / m 2 and 1 g / m 2 All unit increments are included. For example, a cellulose layer may have a thickness of about 20 g / m 2 ~about 100g / m 2 , for example, about 30 g / m 2 ~about 70g / m 2 Coated paper products, on the other hand, can have a basis weight of about 25 g / m 2 ~about 250g / m 2 and an overall basis weight of 1 g / m 2 This includes all unit increments. For example, coated paper products are approximately 25 g / m 2 ~Approx. 125g / m 2 , for example, about 35 g / m 2 ~about 90g / m 2 , for example, about 40 g / m 2 ~about 80g / m 2 The sheet may have a basis weight of

[0013] The present disclosure also relates to packaging formed from the coated paper. In one embodiment, the packaging can define a hollow enclosure or interior volume formed between two layers of coated paper. The coated paper can be heat-sealed along the edges of the product.

[0014] Other features and aspects of the disclosure are described in detail below.

[0015] A full and enabling disclosure of the present disclosure is set forth in more detail in the remainder of the specification, which takes reference to the accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of one embodiment of a coated paper product made in accordance with the present disclosure. [Figure 2] 1 is a perspective view of one embodiment of a package made in accordance with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] In the present specification and drawings, repeated use of reference characters is intended to represent same or analogous features or elements of the invention.

[0018] definition As used herein, the term "coating" refers to a film formed on the surface of a cellulose layer. The coating can be a continuous coating or a discontinuous coating. The coating can cover the entire surface of the cellulose layer. In one embodiment, after applying one or more coatings to the cellulose layer, the fibers of the cellulose layer are not exposed to the outside.

[0019] As used herein, "water vapor transmission rate" (MVTR) is measured according to DIN EN ISO 15106-3:2005-01 at a relative humidity of 50% and a temperature of 23°C.

[0020] As used herein, "oxygen transmission rate" (OTR) is measured according to DIN EN ISO test 15105-2:2003 at a relative humidity of 50% and a temperature of 23°C.

[0021] As used herein, the term "biomass" is broadly understood to encompass all types of plant- and animal-derived materials and materials derived therefrom. "Plant- or animal-derived components" herein can be obtained from biomass. As used herein, biomass and plant- or animal-derived components do not include petroleum or petroleum-derived products.

[0022] Biomass for use in the present invention may comprise polymeric compounds, examples of which include lignin and polysaccharides such as starch, cellulose, hemicellulose, also commonly called polyoses, glycogen, and alginates.

[0023] As will be appreciated, certain biomass may include both plant and animal-derived materials. Examples include manure (excrement), human waste, and sewage sludge. The biomass used in the present invention is preferably plant biomass, i.e., biomass of a plant or biomass derived from a plant, although a certain content of animal biomass (i.e., biomass of an animal or biomass derived from an animal) may also be present therein. For example, the biomass may contain up to 30% animal biomass. In a preferred embodiment, the biomass for use in the present disclosure, which is preferably plant biomass, comprises more than 70% by weight, and most preferably more than 90% by weight, of polysaccharides and lignin, calculated on the solid content of the biomass.

[0024] For example, plant biomass may be agricultural plant material (eg, agricultural waste) or any type of wood material.

[0025] Non-limiting examples of biomass include crops, agricultural food crops and waste, feed crop residues, wood (such as wood flour, wood chips, waste wood, sawdust, chips, and waste), straw (including rice straw), grass, leaves, rice husks, and bagasse. Further examples include industrial and municipal waste, including waste paper.

[0026] The term "biomass" as used herein preferably includes monosaccharides such as glucose, ribose, xylose, arabinose, mannose, galactose, fructose, sorbose, fucose, rhamnose, etc., as well as oligosaccharides. As used herein, plant or animal derived ingredients further include plant or animal derived proteins such as milk proteins.

[0027] As used herein, a "biodegradable" component is a component that can be decomposed by living organisms, such as bacteria or fungi. A biodegradable component can be broken down by the action of microorganisms, such as bacteria or fungi, regardless of the presence or absence of oxygen. In one aspect, a biodegradable component meets the requirements of at least one of the international industrial standards ISO Test 17088, EN Test 13432:2001, EN Test 14995, and / or ASTM Test 6400.

[0028] As used herein, the term "compostable" refers to materials that are non-toxic and capable of breaking down into natural elements, including industrially and domestically compostable materials. Compostable materials can, for example, decompose at rates comparable to similar organic materials. Compostable materials break down through exposure to microorganisms, moisture, and / or heat, resulting in a final composted product. Coated paper produced according to the present disclosure can be formulated to meet European Standard EN Test 13432:2001, which sets out the requirements for industrially compostable materials.

[0029] As used herein, the term "water-soluble" means that the component is highly soluble in water, preferably at least 50 g / L, more preferably at least 100 g / L, even more preferably at least 150 g / L, and most preferably at least 250 g / L of the component at 25°C and 1 atmosphere.

[0030] As used herein, the term "water-dispersible" means that the particles of the component can be dispersed in water, e.g., by stirring or homogenization, i.e., can be uniformly and finely distributed in water, so that the particle size is preferably 1 μm or less.

[0031] As used herein, the term "pulp" refers to fibers derived from natural sources, such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto, milkweed, straw, jute, hemp, and bagasse. Pulp fibers include hardwood fibers, softwood fibers, and mixtures thereof.

[0032] As used herein, the term "average fiber length" refers to the average length of fibers, fiber bundles, and / or fibrous materials as determined by microscopic measurements. A sample of at least 20 randomly selected fibers is isolated from a fiber suspension. The fibers are placed on a microscope slide prepared for suspension in water. A color dye is added to the suspended fibers to color them so that cellulose-containing fibers can be distinguished or separated from synthetic fibers. The slide is then placed under a Fisher Stereomaster II microscope (S19642 / S19643 series). Twenty fibers within the sample are measured at 20x linear magnification using a 0-20 mil scale, and the average length, minimum length, maximum length, and deviation or coefficient of variation are calculated. In some cases, the average fiber length is calculated as the weighted average length of fibers (e.g., fibers, fiber bundles, fibrous materials) measured by an instrument such as the Kajaani Fiber Analyzer (Model FS-200) available from Kajaani Oy Electronics (Kajaani, Finland). According to the standard test procedure, samples are treated with maceration fluid to ensure the absence of fiber bundles and debris. Each sample is digested in warm water and diluted to an approximately 0.001% suspension. When tested using the standard Kajaani fiber analysis test procedure, individual test samples of approximately 50-100 ml are taken from the diluted suspension. The weighted average fiber length can be either the arithmetic mean, length-weighted mean, or mass-weighted mean, and can be expressed as follows:

[0033]

number

[0034] During the ceremony, k = maximum fiber length x i = fiber length n i = length x i Number of fibers with n = total number of fibers measured.

[0035] Those skilled in the art will appreciate that the discussion herein is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present disclosure.

[0036] Generally, the present disclosure relates to coated paper having excellent barrier and heat-sealing properties. A particular advantage is that the coated paper of the present disclosure can be constructed entirely from sustainable materials. Thus, in one aspect, the coated paper is not only biodegradable and / or compostable, preferably home compostable, but also suitable for forming any type of packaging, particularly rigid packaging.

[0037] For example, referring to Figure 1, one embodiment of a coated paper 10 made in accordance with the present disclosure is shown. As shown, the coated paper 10 includes a cellulosic layer 12 coated on one side with at least two different coating layers. In particular, the coated paper 10 includes a barrier coating 14 that can be applied directly to one side of the cellulosic layer 12. A heat-sealable coating 16 is applied over the barrier coating 14 on the same side of the cellulosic layer 12.

[0038] As explained in more detail below, the barrier coating 14 is formed from components of plant or animal origin, is preferably water-soluble or water-dispersible, and more preferably water-soluble, and provides barrier properties to the coated paper 10, particularly low oxygen permeability.

[0039] Meanwhile, the heat-sealable coating 16 is applied over the barrier coating 14 to protect it. In particular, the heat-sealable coating 16 prevents the barrier coating 14 from being exposed to moisture, thereby preventing degradation of the barrier coating 14. Furthermore, the heat-sealable coating 16 further improves the barrier properties of the overall product, achieving particularly low moisture vapor transmission rates. The heat-sealable coating 16 is also heat-sealable and, therefore, can be used to bond coated paper to adjacent coated paper to produce packaging or other articles requiring hollow enclosures.

[0040] The heat-sealable coating 16 may include a wax (preferably a bio-based wax) alone or in combination with other components, such as a polymer. For example, the polymer combined with the wax may be a polyester polymer, a polysaccharide, a polysaccharide ester, a polysaccharide ether, a polysaccharide ether ester, a latex polymer, or a combination thereof.

[0041] In one embodiment, the barrier coating 14 and the heat-sealable coating 16 can be applied to one side of the cellulose layer, with a different coating applied to the other side. For example, a print-receptive coating that can better accept printed matter can be applied to the other side of the cellulose layer. The print-receptive coating can be, for example, a bio-based polymer layer that optionally contains filler particles, such as clay particles. In yet another aspect, the other side of the coated paper 10 can include a barrier coating and / or a heat-sealable coating. For example, in one embodiment, each side of the cellulose layer 12 can include a barrier coating 14 disposed adjacent to the surface of the cellulose layer and a heat-sealable coating 16 disposed on each barrier coating.

[0042] The coated paper 10 shown in Figure 1 is not only biodegradable and / or compostable, preferably home compostable, but also has an excellent balance of properties. For example, the coated paper 10 is flexible and has a Young's modulus suitable for packaging applications. Furthermore, the coated paper 10 has high strength and tear resistance. For example, the tensile strength of the coated paper in the machine direction is about 50 N / 15 mm or greater, preferably about 55 N / 15 mm or greater, more preferably about 60 N / 15 mm or greater, even more preferably about 65 N / 15 mm or greater, even more preferably about 70 N / 15 mm or greater, and most preferably about 75 N / 15 mm or greater, and typically about 100 N / 15 mm or less.

[0043] The coated paper 10 can also be configured to have excellent barrier properties. For example, the coated paper 10 can have a thickness of about 10 g / m 2 / 24 hours or less, preferably about 9 g / m 2 / 24 hours or less, more preferably about 8 g / m 2 / 24 hours or less, even more preferably about 7 g / m 2 / 24 hours or less, and even more preferably about 6 g / m 2 / 24 hours, and even more preferably about 5 g / m 2 / 24 hours or less, and even more preferably about 4 g / m 2 / 24 hours or less, and even more preferably about 3 g / m 2 / 24 hours or less, and even more preferably about 2 g / m 2 / 24 hours or less, most preferably about 1 g / m 2 The coated paper 10 can exhibit a moisture vapor transmission rate (MVTR) of less than 1 / 24 hours. The coated paper 10 can also exhibit excellent oxygen barrier properties. For example, the coated paper 10 can be applied to a surface of approximately 2 cm 3 / m 2 / less than 24 hours, preferably about 1.75 cm 3 / m 2 / less than 24 hours, more preferably about 1.5 cm 3 / m 2 / less than 24 hours, even more preferably about 1.25 cm 3 / m 2 / less than 24 hours, and even more preferably about 1 cm 3 / m2 / 24 hours or less, and even more preferably about 0.75 cm 3 / m 2 / less than 24 hours, and even more preferably about 0.5 cm 3 / m 2 / less than 24 hours, most preferably about 0.25 cm 3 / m 2 It can exhibit an oxygen transmission rate (OTR) of less than 24 hours.

[0044] The coated paper 10 can also define an outer surface 18 that is a heat-sealable surface, as shown in FIG. 1 . The surface 18 can be formulated, for example, to be tack-free at room temperature. The surface 18, or heat-sealable coating 16, can produce a heat seal at temperatures greater than about 100°C, such as greater than about 110°C, for example, greater than about 120°C, for example, greater than about 130°C, for example, greater than about 140°C, for example, greater than about 150°C, for example, greater than about 160°C, for example, greater than about 170°C, for example, greater than about 180°C, and less than about 250°C, for example, less than about 230°C, for example, less than about 220°C, for example, less than about 210°C, for example, less than about 200°C, for example, less than about 190°C, for example, less than about 180°C. Particularly advantageously, the coating exhibits excellent heat-sealability, even at relatively low basis weights.

[0045] The coated paper 10 shown in FIG. 1 can be used to form various packages using a variety of techniques and processes. For illustrative purposes, referring to FIG. 2, a package 50 that can be formed in accordance with the present disclosure is shown. The package 50 can be manufactured from the coated paper 10 shown in FIG. 1. The package 50 includes a bottom 52, a face 54, and a top 56. In this embodiment, the package 50 is formed from two opposing coated paper layers manufactured in accordance with the present disclosure. Each face of the package can be manufactured from an individual piece or sheet of coated paper, or it can be formed by folding the coated paper over itself. The heat-sealable coating 16 on the coated paper 10 can be used to seal the edges of the package 50. For example, as shown in FIG. 2, the package 50 includes a sealed edge 60 formed by adhering adjacent heat-sealable coatings. The edge can be formed, for example, by applying heat and pressure to the heat-sealable coating 16. However, in other embodiments, various other forms of energy can be used to form the sealed edge. For example, ultrasonic energy can also be used.

[0046] The package 50 shown in Figure 2 can include a hollow enclosure for housing a number of different items. The coated paper is made from sustainable, biodegradable and / or compostable materials, preferably home compostable materials, and is therefore suitable for contact with food. Thus, in one embodiment, the package 50 can be designed to house food products such as snack foods. The package can also house a variety of other items, including hardware, consumer products, and the like.

[0047] In one embodiment, when filling a package 50, as shown in Figure 2, two coated paper layers can be sealed together at the edges to form a voluminous hollow interior. One or more products can then be placed into the hollow interior, and the remaining edges of the package can be sealed. To seal the package, the open end of the package can be brought into contact with a sealing device that applies sufficient heat and pressure to activate the heat-sealable coating and form a thermal bond with the heat-sealable coating on the opposing side.

[0048] As noted above, the coated paper may include a barrier coating applied directly to one side of the cellulose layer. According to the present disclosure, the barrier coating significantly improves the barrier properties of the coated paper, providing particularly low oxygen transmission rates, and is fully biodegradable and / or compostable, preferably home compostable.

[0049] In one embodiment, the barrier coating is formed from plant- or animal-derived components. The plant- or animal-derived components used in the present invention do not include petroleum or petroleum-derived products. The plant- or animal-derived components used in the barrier coating are preferably water-soluble or water-dispersible, more preferably water-soluble. Being water-soluble or water-dispersible allows the plant- or animal-derived components to be easily applied to the cellulose layer and dried. In one aspect, the plant- or animal-derived components are amorphous.

[0050] Examples of plant- or animal-derived ingredients used in barrier coatings include plant- or animal-derived proteins, such as milk proteins, and polysaccharides, such as alginates, cellulosic materials, or modified starches. Suitable cellulosic materials include nanofibrillated cellulose (NFC), microfibrillated cellulose (MFC), nanocrystalline cellulose (NCC), or microcrystalline cellulose (MCC). In a preferred embodiment, the plant- or animal-derived ingredient is an animal-derived protein, more preferably a milk protein. Milk proteins used in barrier coatings may contain trace amounts of residual lactic acid.

[0051] In one embodiment, the barrier coating does not include sugar fatty acid esters. As used herein, sugar fatty acid esters include fatty acid esters of all sugars, including monosaccharides, disaccharides, and trisaccharides, and the fatty acid moieties in the sugar fatty acid esters may be saturated, unsaturated, or a combination thereof.

[0052] The barrier coating can include only the plant- or animal-derived components listed above, or can include various other components in addition to these. For example, the barrier coating can include a biodegradable and / or compostable polymer and / or a biodegradable and / or compostable filler. In one aspect, for example, the barrier coating can include a combination of a plant- or animal-derived component and a polyvinyl alcohol polymer. Polyvinyl alcohol polymers can be synthesized from polyvinyl acetate and formed into a variety of products with different molecular weights and degrees of hydrolysis. Polyvinyl alcohols particularly suitable for incorporation into barrier coatings can have a relatively high degree of hydrolysis, e.g., greater than about 90%, e.g., greater than about 92%, e.g., greater than about 94%, e.g., greater than about 96%, e.g., greater than about 98%. The degree of hydrolysis can be less than about 100%, e.g., less than about 99.5%, e.g., less than about 99%. The viscosity of polyvinyl alcohol can generally be less than about 50 cPs, for example less than about 40 cPs, for example less than about 35 cPs, and generally greater than about 10 cPs, for example greater than about 15 cPs, for example greater than about 20 cPs, for example greater than about 25 cPs. The viscosity of polyvinyl alcohol can be measured according to DIN test 53019, particularly DIN 53019-1:2008-09. The viscosity can be measured using a Brookfield viscometer.

[0053] In one embodiment, the barrier coating comprises a plant- or animal-derived component, a polyvinyl alcohol polymer, and, optionally, a filler. The polyvinyl alcohol polymer may be as defined above. The optional filler is not particularly defined. For example, in addition to the cellulose fillers described below, the filler may also be an inorganic filler such as kaolinite (kaolin) and / or talc (talcum). In this embodiment, the barrier coating preferably comprises 10% to 50%, e.g., 10% to 20%, by weight of a plant- or animal-derived component, preferably milk protein, and a polyvinyl alcohol polymer in an amount totaling 100% by weight, i.e., the polyvinyl alcohol polymer forms the remainder of the barrier coating.

[0054] Polyvinyl alcohol may optionally be included in the barrier coating. However, if included, the polyvinyl alcohol may be present in an amount of about 3% by weight or more, such as about 5% by weight or more, for example, about 8% by weight or more, for example, about 10% by weight or more, for example, about 15% by weight or more, for example, about 20% by weight or more, for example, about 25% by weight or more, for example, about 30% by weight or more, and typically about 60% by weight or less, for example, about 40% by weight or less, for example, about 20% by weight or less, for example, about 10% by weight or less, based on the dry weight of the barrier coating. In a preferred embodiment, the barrier coating comprises a milk protein and a polyvinyl alcohol polymer. More preferably, the barrier coating comprises 50-80% by weight of milk protein and 20-50% by weight of polyvinyl alcohol polymer, even more preferably 55-75% by weight of milk protein and 25-45% by weight of polyvinyl alcohol polymer, and even more preferably 60-70% by weight of milk protein and 30-40% by weight of polyvinyl alcohol polymer, based on the total weight of the barrier coating.

[0055] In addition to the polymer, the barrier coating can also include a filler, particularly a biodegradable and / or compostable filler. For example, in one embodiment, the barrier coating can include a cellulose filler, such as microcrystalline cellulose, nanocrystalline cellulose, etc. The filler, such as a cellulose filler, can generally be present in the barrier coating in an amount of about 20% by weight or less, such as about 15% by weight or less, such as about 10% by weight or less, such as about 8% by weight or less, for example, about 5% by weight or less, based on the total weight of the barrier coating. The filler, such as a cellulose filler, can generally be present in the barrier coating in an amount of about 0.1% by weight or more, such as about 1% by weight or more, such as about 2% by weight or more, for example, about 5% by weight or more, based on the total weight of the barrier coating.

[0056] The barrier coating primarily forms a coating on the surface of the cellulose layer, but can also penetrate the cellulose layer. For example, the barrier coating can extend through more than about 3%, such as more than about 5%, such as more than about 10%, such as more than about 20%, such as more than about 30%, such as more than about 40%, such as more than about 50%, or such as more than about 60% of the thickness of the cellulose layer. The barrier coating can extend through less than about 70%, such as less than about 50%, such as less than about 30%, such as less than about 20%, or such as less than about 10% of the thickness of the cellulose layer. The amount of penetration of the barrier coating into the thickness of the cellulose layer depends on many factors, including the viscosity of the barrier coating at the time of application and the porosity of the cellulose layer.

[0057] The basis weight of the barrier layer may also vary depending on various factors such as the particular application, the end use of the coated paper, the basis weight of the cellulosic layer, etc. In one embodiment, the barrier coating has a surface area of ​​about 8 g / m 2 ~about 30g / m 2 and 1 g / m 2 This includes all unit increments. For example, the basis weight of a barrier coating is approximately 10 g / m 2 or more, for example, about 12 g / m 2 or more, for example, about 14 g / m 2 or more, for example, about 16 g / m 2or more, for example, about 18 g / m 2 or more, and about 25 g / m 2 Below, for example, about 23 g / m 2 Below, for example, about 20 g / m 2 Below, for example, about 18 g / m 2 Below, for example, about 16 g / m 2 Below, for example, about 15 g / m 2 It can be as follows:

[0058] As described above, the barrier coating applied to the cellulose layer is covered with a heat-sealable coating. The heat-sealable coating can be applied directly to the barrier coating and incorporated into the coated paper without an adhesive or tie layer between the barrier coating and the heat-sealable coating. In fact, the coated paper of the present disclosure can be produced without an adhesive layer between the coatings or between the cellulose layer and the coating layer.

[0059] Heat-sealable coatings typically contain wax, preferably a bio-based wax, which can be produced from biomass resources. Wax not only provides heat-sealability but also improves the hydrophobicity, slipperiness, and abrasion resistance of the coated paper. Heat-sealable coatings also improve surface and barrier properties, particularly low water vapor transmission rates.

[0060] The wax is preferably a vegetable wax or an animal wax, more preferably a vegetable wax.

[0061] Animal waxes typically include wax esters derived from various fatty acids and carboxylic alcohols. The animal wax may be a wax selected from the group of insect secretion waxes, spermaceti and lanolin.

[0062] The insect wax is preferably beeswax. The main component of beeswax is myricyl palmitate, an ester of triacontanol and palmitic acid. The melting point of beeswax is in the range of 60-65°C. Cetacean wax is found in large amounts in the blubber of sperm whales. Cetacean wax is primarily composed of cetyl palmitate. Lanolin is a wax obtained from sheep's wool and contains sterol esters.

[0063] Vegetable waxes are complex mixtures of hydrocarbons, alcohols, aldehydes, ketones, esters, acids, and combinations thereof, deposited on the outer layer of epidermal cells. Vegetable waxes are water-repellent components typically found in the amorphous layer of the outer surface of plants. Vegetable waxes within the meaning of the present invention also include vegetable oils or waxes obtained from vegetable oils by chemical reactions such as hydrogenation.

[0064] The vegetable wax may more preferably be one or more selected from the group consisting of candelilla wax, carnauba wax, rice bran wax, soy wax, sugarcane wax, sunflower wax, pea wax, coconut wax, and palm wax, and even more preferably be soy wax.

[0065] Candelilla wax is primarily obtained from the leaves of the plant Euphorbia antisyphilitica Zuccarini. Unrefined candelilla wax contains approximately 40-45% by weight of hydrocarbons, 35-45% by weight of waxes, resins, and sitosterol esters, 5-10% by weight of free wax and resin acids, 4-8% by weight of lactones, and 2-8% by weight of free wax and resin alcohols.

[0066] Carnauba wax is primarily obtained from the Brazilian palm, Copernicia cerifera Martius, also known as the carnauba wax palm. Carnauba wax is found on the upper and lower surfaces of the palm leaves. Carnauba wax is rich in unesterified alcohols, x-hydroxyesters, and hydroxylated cinnamic acid esters. Carnauba wax is one of the hardest vegetable waxes, with a melting temperature of approximately 80°C.

[0067] Rice bran wax is another high-melting wax found in the husks of rice, Oryza sativa. It is obtained as a by-product from the dewaxing of rice bran oil. The main components of rice bran wax are esters of even-numbered fatty acids and higher alcohols. Other components include free fatty acids (palmitic acid), phospholipids, phytosterols, and squalene. The hydrocarbon content of rice bran wax is typically low, at 2% by weight.

[0068] Sunflower wax is found in the seeds and seed husks of Helianthus annuus (sunflower). It is obtained by dewaxing sunflower oil. Sunflower wax is a hard, high-melting wax composed primarily of long-chain saturated fatty esters.

[0069] Soy wax is obtained by hydrogenating soybean oil. It is a triglyceride with a high percentage of stearic acid. It is generally softer than paraffin wax and has a lower melting point than paraffin wax. Its melting point ranges from about 50°C to about 80°C.

[0070] Sugarcane wax is indigestible and harmless to health. Its refined form has a pale yellowish color. Its high melting point of 75-80°C makes it stable even in direct sunlight. Sugarcane wax provides good oil and solvent retention for anionic bright emulsions.

[0071] The wax used in the present invention is preferably one or more waxes selected from the group consisting of rice bran wax, soy wax, sugarcane wax, and beeswax, and more preferably soy wax.

[0072] The wax preferably has a dropping point in the range of 60°C to 120°C, more preferably in the range of 60 to 110°C. The dropping point is a characteristic property of the wax. To measure the dropping point, the sample is heated until it changes from a solid to a liquid state. Specifically, the dropping point is the temperature at which the first drop of molten material precipitates from a standardized cup with a defined orifice under controlled test conditions in an oven. In the present invention, the dropping point can be determined according to the procedure described in DIN ISO 2176:1997-05.

[0073] The heat-sealable coating used in the present invention may preferably comprise 10 to 90% by weight of wax, more preferably 10 to 80% by weight of wax, even more preferably 10 to 60% by weight of wax, and most preferably 10 to 40% by weight of wax, based on the total weight of the heat-sealable coating. In addition to wax, the heat-sealable coating can optionally contain polymers and various other ingredients. The polymer used in the heat-sealable coating can be a polymer selected from the group consisting of polyesters, polysaccharides, polysaccharide ethers, polysaccharide esters, polysaccharide ether esters, and latex polymers. For example, combining such polymers with wax can improve the heat-sealability of the heat-sealable coating. Furthermore, such polymers can completely replace traditionally used petroleum-derived heat-sealable polymers. These polymers can be produced, for example, from biomass. Therefore, the polymers are sustainable and environmentally friendly, similar to bio-based waxes, and exhibit excellent heat-sealability. If home compostable paper is desired, the heat-sealable coating does not contain latex polymers.

[0074] The polymer is preferably a thermoplastic polymer, which further improves the heat sealability.

[0075] The polymer is preferably a thermoplastic polymer having a melting point in the range of 60 to 200° C., more preferably 100 to 180° C., and most preferably 110 to 180° C. When the heat-sealable coating of the coated paper of the present disclosure comprises a thermoplastic polymer having a melting point in the range of 60 to 200° C., the heat-sealability of the coated paper is improved. When the coating of the coated paper of the present disclosure comprises a thermoplastic polymer having a melting point in the range of 100 to 180° C., the heat-sealability is further improved.

[0076] Additionally, the polymer is preferably a biomass-based polymer, which makes the coated paper more sustainable and environmentally friendly.

[0077] The polyester may be selected from the group consisting of polyhydroxyalkanoates, polylactic acids, polyglycolic acids, polybutylene succinates, polycaprolactones, polybutylene adipate terephthalates, and polylactic acid-polyethylene glycols.

[0078] Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoic acids. They are thermoplastic. They can be homopolyesters or copolyesters, and their properties vary depending on their chemical composition, i.e., the hydroxyalkanoic acids they contain.

[0079] The PHA may be one or more polyesters selected from the group consisting of poly(3-hydroxypropionate), poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(3-hydroxyvalerate), poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate), poly(3-hydroxyoctanoate), poly(3-hydroxynonanoate), poly(3-hydroxydecanoate), poly(3-hydroxyundecanoate), poly(3-hydroxydodecanoate), poly(3-hydroxytetradecanoate), poly(3-hydroxypentadecanoate), and poly(3-hydroxyhexadecanoate). The PHA may also be one or more copolyesters obtained by copolymerization of two or more hydroxyalkanoic acids. More particularly, the PHA copolyester may be one or more selected from the group consisting of poly(3-hydroxypropionate-co-3-hydroxybutyrate), poly(3-hydroxypropionate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate).

[0080] The PHA is preferably one or more polyesters selected from the group consisting of poly(3-hydroxypropionate), poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate). The PHA is most preferably poly(3-hydroxybutyrate).

[0081] Polybutylene adipate terephthalate is preferably a block copolymer. Polylactic acid-polyethylene glycol is preferably a block copolymer.

[0082] The polysaccharide may be one or more selected from the group consisting of starch, cellulose, arabinoxylan, chitin, and pectin, and the polysaccharide is preferably starch or cellulose.

[0083] In order to improve the thermoplastic properties of the polysaccharide, a plasticizer may be added to the polysaccharide, thus obtaining a thermoplastic polysaccharide comprising the polysaccharide and the plasticizer.

[0084] The plasticizer may be one or more compounds selected from the group consisting of polyhydric alcohols, diols, esters of polyhydric alcohols, and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids. The plasticizer is preferably a polyhydric alcohol or a diol, and most preferably one or more compounds selected from glycerol, glycol, and sorbitol. The glycerin may be vegetable glycerin (VG). Vegetable glycerin is glycerin obtained from vegetable oils such as soybean oil, coconut oil, and palm oil.

[0085] The thermoplastic polysaccharide preferably comprises at least one of starch and cellulose. In other words, the thermoplastic polysaccharide is preferably thermoplastic starch, thermoplastic cellulose, or a combination thereof, more preferably thermoplastic starch. The thermoplastic starch preferably comprises one or more plasticizers selected from the group consisting of glycerol, glycol, and sorbitol.

[0086] In one embodiment, the thermoplastic polysaccharide is obtained from corn agricultural waste.

[0087] The polymers used in the heat-sealable coatings of the present invention may be polysaccharide ethers, polysaccharide esters or polysaccharide ether esters.

[0088] The polysaccharide ether is preferably a cellulose ether. The polysaccharide ether is more preferably carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethylmethylcellulose, and hydroxypropylmethylcellulose. The polysaccharide ether is most preferably carboxymethylcellulose, methylcellulose, and hydroxyethylcellulose.

[0089] The polysaccharide ester may be a cellulose ester, for example, cellulose acetate.

[0090] The polysaccharide ether ester may be a cellulose ether ester, such as hydroxypropylmethylcellulose acetate succinate or carboxymethylcellulose acetate butyrate.

[0091] The polymer is most preferably one or more selected from the group consisting of poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), polylactic acid, polylactic acid-polyethylene glycol block copolymer, polybutylene adipate terephthalate, and thermoplastic starch.

[0092] The heat-sealable coating may contain one or more of the above polymers in an amount generally of about 10% by weight or more, preferably about 20% by weight or more, more preferably about 30% by weight or more, even more preferably about 40% by weight or more, and most preferably about 50% by weight or more, based on the total weight of the heat-sealable coating. The one or more polymers may be present in the heat-sealable coating in an amount generally of about 90% by weight or less, preferably about 80% by weight or less, more preferably about 70% by weight or less, and most preferably about 60% by weight or less, based on the total weight of the heat-sealable coating.

[0093] The heat-sealable coating used in the present invention preferably contains 10 to 90% by weight of wax and 10 to 90% by weight of polymer, based on the total weight of the heat-sealable coating, and more preferably 10 to 40% by weight of wax and 60 to 90% by weight of polymer. Furthermore, paper coated with a heat-sealable coating containing 10 to 90% by weight of wax and 10 to 90% by weight of polymer, based on the total weight of the heat-sealable coating, combines a paper-like appearance and feel with processability and heat-sealability comparable to that of plastic film. When the heat-sealable coating contains 10 to 40% by weight of wax and 60 to 90% by weight of polymer, based on the total weight of the heat-sealable coating, the heat-sealability of the coated paper is further improved. Furthermore, when the heat-sealable coating contains 10 to 40% by weight of wax and 60 to 90% by weight of polymer, based on the total weight of the heat-sealable coating, the coated paper has improved water vapor barrier properties. In a particularly preferred embodiment, the heat-sealable coating comprises 20-40% by weight of wax and 60-80% by weight of polymer, based on the total weight of the heat-sealable coating, which provides an optimal balance of water vapor barrier properties and heat-sealability.

[0094] The heat-sealable coating used in the present invention may preferably comprise soy wax and a thermoplastic polysaccharide, preferably obtained from corn agricultural waste.

[0095] The heat-sealable coating used in the present disclosure may include one or more additives, which may be at least one compound selected from the group consisting of rheology modifiers and softeners.

[0096] The rheology modifier is preferably one or more compounds selected from the group consisting of cellulose, starch, or derivatives thereof. The rheology modifier is preferably water-soluble or water-dispersible. The rheology modifier is more preferably biomass-based and / or biodegradable. The rheology modifier thickens the emulsion and improves its stability. Therefore, dripping during application of the coating can be avoided.

[0097] The use of a rheology modifier selected from the group consisting of cellulose, starch, and their derivatives improves the emulsion stability of the heat-sealable coating. At the same time, such rheology modifiers are water-soluble or water-dispersible, biomass-based, and biodegradable, making them sustainable. Therefore, a sustainable, more environmentally friendly heat-sealable coated paper suitable for use as a packaging material and having a desirable, preferably paper-like, appearance and feel can be obtained.

[0098] The cellulose may be microfine cellulose, preferably powdered microfine cellulose such as ARBOCEL manufactured by JRS.

[0099] The cellulose derivative may be a cellulose ether or a cellulose ether ester. The cellulose ether is preferably carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, ethyl methyl cellulose, or hydroxypropyl methyl cellulose. The cellulose ether is more preferably carboxymethyl cellulose, methyl cellulose, or hydroxyethyl cellulose. The hydroxyethyl cellulose may be, for example, Cellosize™ QP-100 manufactured by Dow. The cellulose ether ester may be hydroxypropyl methyl cellulose acetate succinate or carboxymethyl cellulose acetate butyrate.

[0100] The starch derivative may be, for example, a phosphorylated distarch phosphate, preferably a waxy corn-based phosphorylated distarch phosphate such as AGENAJEL 20.350 from AGRANA STARKE.

[0101] The heat-sealable coating may comprise 0 to 3 wt. %, more preferably 0.5 to 2 wt. %, of a rheology modifier, based on the total weight of the heat-sealable coating.

[0102] The heat-sealable coating of the present disclosure may also contain a softener. The softener may be one or more compounds selected from the group consisting of polyhydric alcohols, diols, esters of polyhydric alcohols, and aliphatic esters of mono-, di-, or polycarboxylic acids. The softener is preferably a polyhydric alcohol or a diol, and most preferably one or more compounds selected from glycerol, glycol, and sorbitol. The glycerin may be vegetable glycerin (VG). Vegetable glycerin is glycerin obtained from vegetable oils such as soybean oil, coconut oil, and palm oil.

[0103] The addition of a softener further improves the processability of the coating and the heat sealability of the coated paper.

[0104] Glycerol, glycol, and sorbitol are water-soluble, biodegradable, and can be produced from biomass, therefore, coatings comprising softeners selected from the group consisting of glycerol, glycol, and sorbitol are sustainable and environmentally friendly.

[0105] The heat-sealable coating preferably comprises 0 to 10% by weight, more preferably 2 to 7% by weight, of a softener, based on the total weight of the heat-sealable coating.

[0106] In yet another embodiment, the heat-sealable coating may include a filler. The filler included in the heat-sealable coating may be an inorganic filler. The filler is preferably a filler based on naturally occurring raw materials such as clay for reasons of sustainability and environmental protection. The filler is even more preferably a clay mineral, and most preferably a layered silicate mineral such as kaolinite. The filler may also be a pigment, more preferably a pigment based on naturally occurring raw materials such as clay, preferably a layered silicate mineral such as kaolinite.

[0107] The pigment may have a steep particle size distribution. In the most preferred embodiment, 90% by weight of the pigment particles have a particle size of less than 5 μm. Such a particle size distribution improves print and sheet gloss. For example, high-brightness coating pigments such as CAPIM DG slurry from Capim Kaolin can be used. The good rheological properties of slurries of pigment particles with the above particle size distribution allow for high-speed application of fillers, for example, in high-speed blade and metering size press applications.

[0108] The heat-sealable coating preferably comprises 0 to 20% by weight, more preferably 3 to 15% by weight, of filler, based on the total weight of the heat-sealable coating. In a preferred embodiment, the heat-sealable coating comprises, based on the total weight of the heat-sealable coating, 10-90% by weight of polymer, 10-90% by weight of wax, 0-3% by weight of rheology modifier, 0-10% by weight of softener, and 0-20% by weight of filler. In a more preferred embodiment, the heat-sealable coating comprises, based on the total weight of the heat-sealable coating, 60-90% by weight of polymer, 10-40% by weight of wax, 0-3% by weight of rheology modifier, 0-10% by weight of softener, and 0-20% by weight of filler. In an even more preferred embodiment, the heat-sealable coating consists of 60-90% by weight of polymer, 10-40% by weight of wax, 0-3% by weight of rheology modifier, 0-10% by weight of softener, and 0-20% by weight of filler. In a most preferred embodiment, the heat-sealable coating comprises 60-80% by weight of polymer, 20-40% by weight of wax, 0-3% by weight of rheology modifier, 0-10% by weight of softener, and 0-20% by weight of filler. If home compostable paper is desired, the heat-sealable coating does not contain a latex polymer.

[0109] The basis weight of a heat-sealable coating may vary depending on the specific application and end use of the coated paper. Generally, the basis weight of a heat-sealable coating is about 1 g / m 2 ~about 25g / m 2 and 1g / m 2 All unit increments are included. For example, a heat-sealable coating may be approximately 3 g / m 2 More than, for example, about 4 g / m 2 More than, for example, about 5 g / m 2 More than, for example, about 6 g / m 2 More than, for example, about 7 g / m 2 or more, for example, about 8 g / m 2 The heat-sealable coating may have a basis weight of about 25 g / m or more. 2 Below, for example, about 23 g / m 2 Below, for example, about 20 g / m 2 Below, for example, about 18 g / m 2Below, for example, about 15 g / m 2 Below, for example, about 14 g / m 2 It can be as follows:

[0110] The coated paper of the present disclosure preferably comprises a barrier coating comprising a milk protein, either alone or in combination with a polyvinyl alcohol polymer, and a heat-sealable coating comprising a vegetable wax, such as soy wax, and a thermoplastic polysaccharide, preferably derived from agricultural waste from corn. More preferably, the barrier coating comprises 50-80% by weight of the milk protein and 20-50% by weight of the polyvinyl alcohol polymer, even more preferably 55-75% by weight of the milk protein and 25-45% by weight of the polyvinyl alcohol polymer, and even more preferably 60-70% by weight of the milk protein and 30-40% by weight of the polyvinyl alcohol polymer, based on the total weight of the barrier coating.

[0111] The basis weight of the barrier coating containing milk protein is preferably 2 to 20 g / m 2 , more preferably 3 to 15 g / m 2 , and even more preferably 7 to 12 g / m 2 The basis weight of the heat-sealable coating comprising vegetable wax and thermoplastic polysaccharide, preferably obtained from corn agricultural waste, is preferably between 2 and 20 g / m 2 , more preferably 3 to 15 g / m 2 , and even more preferably 4 to 14 g / m 2 is.

[0112] As noted above, both the barrier coating and the heat-sealable coating are applied to a cellulose layer. The cellulose layer can be made, for example, from a variety of different cellulose fibers. Typically, the cellulose layer has a thickness of about 20 g / m 2 ~about 200g / m 2 and 1 g / m 2 All unit increments are included. For example, a cellulose layer may have a thickness of about 25 g / m 2 or more, for example, about 30 g / m2 or more, for example, about 40 g / m 2 or more, for example, about 50 g / m 2 More than, for example, about 60 g / m 2 or more, for example, about 70 g / m 2 The cellulose layer generally has a basis weight of about 200 g / m 2 Below, for example, about 120 g / m 2 For example, about 110 g / m 2 Below, for example, about 100 g / m 2 Below, for example, about 90 g / m 2 Below, for example, about 80 g / m 2 Below, for example, about 70 g / m 2 Below, for example, about 60 g / m 2 The following is the result.

[0113] The thickness of the cellulose layer is preferably 35 to 200 μm, more preferably 40 to 160 μm. When the cellulose layer is not subjected to a step of compressing the cellulose layer in the longitudinal direction to obtain an extensible cellulose layer, the cellulose layer has a thickness of even more preferably 40 to 70 μm, most preferably 50 to 60 μm. When the cellulose layer is subjected to a step of compressing the cellulose layer in the longitudinal direction, such as creping, the cellulose layer after being compressed in the longitudinal direction has a thickness of even more preferably 60 to 150 μm, most preferably 60 to 120 μm.

[0114] The basis weight of the coated paper or the entire product is generally about 21 g / m 2 ~about 250g / m 2 and 1g / m 2 This includes all unit increments. For example, coated paper is approximately 30 g / m 2 or more, for example, about 35 g / m 2 or more, for example, about 40 g / m 2 or more, for example, about 45 g / m 2 More than, for example, about 50 g / m 2 or more, for example, about 55 g / m 2 More than, for example, about 60 g / m 2 More than, for example, about 65 g / m 2 Coated paper generally has a basis weight of about 150 g / m 2Below, for example, about 125 g / m 2 Below, for example, about 100 g / m 2 Below, for example, about 95 g / m 2 Below, for example, about 90 g / m 2 Below, for example, about 85 g / m 2 Below, for example, about 80 g / m 2 It can be as follows:

[0115] The basis weight of the cellulose layer and the basis weight of the coated paper are determined according to ISO 536:2019-11. The thickness of the cellulose layer and the coated paper can be measured according to EN ISO 534:2012-02 at a compression load of 1.0 bar.

[0116] The cellulose layer can be made from any suitable papermaking fiber. Fibers suitable for making the cellulose layer include, for example, natural or synthetic cellulose fibers, including, but not limited to, non-wood fibers such as cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute, bagasse, milkweed, and flax fibers. In one embodiment, the cellulose layer comprises wood fibers or pulp fibers, such as fibers obtained from deciduous and coniferous trees. Such fibers include softwood fibers, such as northern and southern softwood kraft fibers. Other fibers include hardwood fibers, such as eucalyptus, maple, birch, and aspen fibers.

[0117] Other papermaking fibers that can be used include paper broke, recycled fibers, and high-yield fibers. High-yield pulp fibers are papermaking fibers produced by pulping processes that provide a yield of about 65% or greater, e.g., about 75% to about 95%. Such pulping processes include bleached chemi-thermomechanical pulp, chemi-thermomechanical pulp, other thermomechanical pulp, high-yield sulfite pulp, and high-yield kraft pulp.

[0118] In one particular embodiment, the cellulosic layer is made from softwood fibers alone or in combination with hardwood fibers.

[0119] The cellulose layer may be extensible, which allows the coated paper to undergo significant deformation during processing or end use.

[0120] When the cellulose layer is extensible, the coated paper of the present invention exhibits improved elongation and elasticity, especially in the machine direction. Therefore, coated paper having an extensible cellulose layer ("stretch-coated paper") exhibits mechanical properties comparable to those of plastic films conventionally used as packaging materials. Therefore, the improved elongation and elasticity of the stretch-coated paper make it more suitable for use in the same machines used for plastic packaging.

[0121] Additionally, compressing the cellulose layer in the machine direction, for example by creping, has been found to improve the coating adhesion and heat sealability of coated papers.

[0122] High extensibility of the cellulose layer can be created by compressing the cellulose layer in the machine direction (MD), preferably by compressing a wet or dry paper web in the machine direction (MD).

[0123] Longitudinal compression can be achieved by subjecting the cellulose layer to a creping process or by using a Clupak unit, processes which are described in more detail below.

[0124] Stretch coated paper within the meaning of the present invention is coated paper having a longitudinal tensile strength and longitudinal breaking elongation as defined below. More specifically, stretch coated paper within the meaning of the present invention preferably has a longitudinal tensile strength of 40 to 120 N / 15 mm, more preferably 60 to 100 N / 15 mm, and a longitudinal breaking elongation of preferably 3.5 to 25.0%, more preferably 4.5 to 15.0%, even more preferably 5.5 to 12.0%, and most preferably 6.0 to 8.0%. In a particularly preferred embodiment, the stretch coated paper has a longitudinal tensile strength of 60 to 100 N / 15 mm and a longitudinal breaking elongation of 6.0 to 8.0%.

[0125] The tensile strength of the coated paper in the machine direction is preferably 40 to 120 N / 15 mm, more preferably 60 to 100 N / 15 mm. The tensile strength of the heat seal paper in the cross direction is 15 to 70 N / 15 mm, more preferably 20 to 60 N / 15 mm, and most preferably 30 to 50 N / 15 mm.

[0126] The Cobb value of the coated paper, measured on the side containing the coating, is preferably between 1 and 20 g / m 2 , more preferably 1 to 12 g / m 2 , and even more preferably 1 to 8 g / m 2 is.

[0127] The coated paper preferably has a longitudinal tear resistance of 100 to 1000 mN, more preferably 300 to 800 mN, and even more preferably 500 to 800 mN. The transverse tear resistance is preferably 100 to 1000 mN, more preferably 300 to 800 mN, and even more preferably 500 to 800 mN.

[0128] The coated paper preferably has a longitudinal breaking elongation of 3.5 to 25.0%, more preferably 4.5 to 8.0%, and even more preferably 6.0 to 7.0%.

[0129] When the cellulose layer used in the coated paper of the present invention is subjected to a longitudinal compression process, the coated paper becomes more suitable for use in the same machines used for plastic packaging due to its increased extensibility, stretch, elasticity and coating adhesion.

[0130] Longitudinal compression can be achieved by subjecting the cellulosic layer to a creping process, which can be performed either inside the paper machine (wet creping) or outside the paper machine (dry creping).

[0131] More specifically, during creping, the cellulose layer moves on the crepe cylinder, is removed by a doctor blade, and is then sent to a transfer device through the surface of the doctor blade. The creping process is controlled by slowing the transfer device speed, preferably by 10 to 50%, relative to the crepe cylinder. The degree of creping, i.e., the number of folds, can be controlled by adjusting the speed difference between the crepe cylinder and the transfer device. Furthermore, the microstructure can be controlled by the shape and angle of the doctor blade. In this process, the dry content of the cellulose layer is preferably in the range of 30 to 50% by weight, preferably 35 to 45% by weight.

[0132] Longitudinal compression of the cellulose layer can also be achieved by using a Clupak unit.

[0133] The Clupak stretching unit includes a cylinder, a nip bar, a gap between the cylinder and the nip bar, and a rubber band (rubber blanket) placed in the gap. In the Clupak stretching unit, the rubber blanket must pass through the gap between the drying cylinder and the nip bar.

[0134] The nip can be thought of as a Venturi section formed by the rotating drying cylinder and the stationary nip bar, within which an endless rubber blanket is accelerated. The paper web follows the dimensional changes of the rubber surface within the nip due to friction between the paper and the rubber. This is the result of high radial nip pressure and the simultaneous sliding of the paper across the cylinder surface. The dimensional changes of the rubber surface are caused by bending and the Venturi effect. First, the surface of the rubber blanket closest to the paper web is stretched by bending on the nip bar and then further stretched by the Venturi effect. Next, the stretched rubber surface comes into contact with the wet paper web. After passing the center of the nip, the stretched rubber surface begins to recoil due to the deceleration caused by the Venturi effect and the backward bending of the rubber. The paper web is compressed in the MD as it follows the contraction of the rubber surface in the latter half of the nip; these phenomena in the nip become more pronounced as the nip width increases. The final compression level is adjusted by controlling the speed difference of the paper web between the entrance and exit of the Clupak nip.

[0135] Compression in the longitudinal direction using a Clupak unit induces a microcrepe effect in the paper network due to the curling of the fibers. As the cellulose layer is compressed, the fibers are forced closer together, compressing the cellulose layer in the longitudinal direction. This imparts a series of small, generally discontinuous, parallel pleats to the cellulose layer. Microcreping differs from creping primarily in the greater number of pleats, and therefore the greater number of overlapping pleats. Surprisingly, it has been found that microcreping not only increases the elongation of the paper substrate, but also further increases the adhesion of subsequently applied coatings compared to creping using a creping cylinder. Furthermore, microcreping improves the heat sealability of coated papers.

[0136] The cellulosic layer used in the manufacture of the coated paper of this invention may be subjected to a calendering step prior to coating.

[0137] The coated paper of the present invention may also be subjected to a calendering process after the coating and drying processes.

[0138] Calendering improves the smoothness and gloss of coated paper.

[0139] Preferred embodiments of the present invention will now be described.

[0140] In one embodiment, the coated paper comprises: a cellulose layer having a first surface and a second opposing surface; a barrier coating applied to at least a first surface of the cellulose layer, the barrier coating comprising milk protein (preferably 50 to 80% by weight, more preferably 55 to 75% by weight, even more preferably 60 to 70% by weight, based on the weight of the barrier coating); and A heat-sealable coating applied over the barrier coating, the heat-sealable coating comprising soy wax and a thermoplastic polysaccharide preferably derived from corn agricultural waste. If home compostable paper is desired, the heat sealable coating is latex free.

[0141] In another embodiment, the coated paper comprises: a cellulose layer having a first surface and a second opposing surface; a barrier coating applied to at least a first surface of the cellulose layer, the barrier coating comprising a milk protein (preferably 50 to 80% by weight, more preferably 55 to 75% by weight, and even more preferably 60 to 70% by weight, based on the weight of the barrier coating) and a polyvinyl alcohol polymer (preferably 20 to 50% by weight, more preferably 25 to 45% by weight, and even more preferably 30 to 40% by weight, based on the weight of the barrier coating); and A heat-sealable coating applied over the barrier coating, the heat-sealable coating comprising soy wax and a thermoplastic polysaccharide preferably derived from corn agricultural waste. If home compostable paper is desired, the heat sealable coating is latex free.

[0142] In the above preferred embodiment, the basis weight of the cellulose layer is 30 to 70 g / m 2 , barrier coating 8~20g / m 2 , heat-sealable coating 4~15g / m 2 The range is more preferable.

[0143] In another aspect, the present disclosure relates to a method for producing coated paper.

[0144] In one aspect, the method described herein comprises providing a cellulosic layer and applying an aqueous solution or dispersion ("barrier coating composition") to one side of the cellulosic layer. The aqueous solution or dispersion includes plant- or animal-derived components. The applied aqueous solution or dispersion is dried to form a barrier coating on the cellulosic layer. Next, an aqueous dispersion or emulsion ("heat-sealable coating composition") is applied over the barrier coating. The aqueous dispersion or emulsion can contain a wax, either alone or in combination with a polymer. The aqueous dispersion or emulsion is applied over the barrier coating. The aqueous dispersion or emulsion is then dried to form a heat-sealable coating on the barrier coating.

[0145] In one aspect, the cellulosic layer may first be impregnated with an aqueous composition containing plant or animal derived components, preferably water soluble or water dispersible, more preferably water soluble, and subsequently coated with an aqueous dispersion or emulsion that forms a heat-sealable coating.

[0146] In another embodiment, the cellulosic layer may be first impregnated with at least one compound selected from the group consisting of waxes, polyesters, polysaccharides, polysaccharide esters, polysaccharide ethers, polysaccharide ether esters, glycerol, polyethylene glycol, polyvinyl alcohol, softeners, and inorganic fillers.

[0147] In this specification, the term "impregnation" is understood to be synonymous with "saturation". The amount of the various impregnation components in the heat-sealable paper is between 2 and 20 g / m 2 , preferably 3 to 15 g / m 2 , and even more preferably 4 to 12 g / m 2 If the coating is applied to only one side of the cellulose layer, it is preferred to impregnate the cellulose layer.

[0148] As described above, the barrier coating and the heat-sealable coating can be applied to only one side of the cellulose layer. Alternatively, a barrier coating and a heat-sealable coating can be provided on each side of the cellulose layer. When a barrier coating is formed on the cellulose layer, the heat-sealable coating can be formed on the barrier coating using any suitable process or technique, followed by curing and / or drying. For example, the heat-sealable coating can be formed by applying the heat-sealable coating composition to the surface of the barrier coating by spraying, brushing, or rolling. When applied to the surface of the barrier coating, the heat-sealable coating composition undergoes film formation.

[0149] Preferably, a relatively low viscosity liquid heat-sealable coating composition is applied to the barrier coating and cured to form a solid, high molecular weight, polymer-based adhesive film. The heat-sealable coating can also be formed by coalescence-based film formation, which is achieved by combining a wax with polymer particles dispersed in a liquid phase, preferably a latex polymer, most preferably a water-dispersible polymer selected from the group consisting of polyesters, polysaccharides, polysaccharide esters, polysaccharide ethers, and polysaccharide ether esters.

[0150] The heat-sealable coating composition can be an aqueous dispersion or emulsion containing a wax. The wax is preferably the wax defined in the first aspect of the present invention. In other words, the wax is preferably a bio-based wax, more preferably a vegetable wax or an animal wax, and even more preferably a vegetable wax. The wax contained in the heat-sealable coating composition is even more preferably one or more selected from the group consisting of candelilla wax, carnauba wax, rice bran wax, soy wax, sugarcane wax, sunflower wax, pea wax, coconut wax, palm wax, and beeswax, and most preferably soy wax. The wax preferably has a dropping point in the range of 60°C to 120°C.

[0151] The heat-sealable coating composition is preferably an aqueous emulsion containing a wax, more preferably an aqueous emulsion containing a wax and an emulsifier.

[0152] The emulsifier is typically a compound having a polar portion and a non-polar portion. A surfactant can be used as the emulsifier. The emulsifier is preferably an anionic emulsifier or a non-ionic emulsifier, more preferably an anionic emulsifier.

[0153] The solids content of the heat-sealable coating composition, which is an aqueous dispersion or emulsion containing wax, is preferably 10 to 45% by weight, based on the total weight of the heat-sealable coating composition. The viscosity of the barrier coating composition is preferably 200 to 1600 mPas, more preferably 500 to 1200 mPas.

[0154] After the barrier coating composition and the heat-sealable coating composition are applied, they are dried to form a barrier coating and a heat-sealable coating, respectively. In one embodiment, the barrier coating composition can be applied and dried, followed by the heat-sealable coating composition, which can be dried after the barrier coating composition has been applied. Drying can be performed by blowing hot, dry air onto the coating, thereby raising the coating temperature to a point where moisture evaporates from the coated paper, leaving a relatively dry coated paper. During the drying process, the web temperature, i.e., the temperature of the cellulose layer, must be lower than the dropping point of the wax. Therefore, the web temperature during drying is preferably below 120°C. The web temperature of the paper can be determined by non-contact temperature measurement using an infrared non-contact thermometer.

[0155] The cellulose layer can be a wet-laid base sheet that is also extensible. The cellulose layer is fed into a first coating device, and an aqueous composition is applied to one side of the cellulose layer. The barrier coating can be applied to the cellulose layer using various coating techniques, such as a rod coater, curtain coater, or air knife, to form a coating having the desired thickness and / or basis weight. In this embodiment, the first coating, or barrier coating, is then dried.

[0156] The heat-sealable coating is applied using any of the coating techniques described above, and then the heat-sealable coating is dried in a second drying step.

[0157] After the second drying step, the coated paper passes through a single-nip calender, then through a cooling roller, and finally to a winder.

[0158] Alternatively, the barrier coating can be formed on one side of the cellulose layer by an extrusion process, in which a barrier coating composition is extruded onto one side of the cellulose layer to form the barrier coating.

[0159] Test Method The water vapor transmission rate (MVTR) can be measured according to DIN EN ISO 15106-3:2005-01 at a relative humidity of 50% and a temperature of 23°C. "Oxygen transmission rate" (OTR) can be measured according to DIN EN ISO test 15105-2:2003 at a relative humidity of 50% and a temperature of 23°C. Tensile strength and elongation at break can be measured according to ISO 1924:2016-08. The tear resistance can be measured in accordance with DIN EN ISO 1974:2012. The basis weight of the cellulose layer and the coated paper can be measured according to ISO 536:2019-11. The basis weight of the barrier coating and the heat-sealable coating can be calculated therefrom. The thickness can be measured according to EN ISO 534:2012-02 at a compressive load of 1.0 bar. Cobb value can be measured according to ISO 535:2014. Samples are measured after 10 minutes.

[0160] The present disclosure may be better understood with reference to the following examples. [Example]

[0161] Coated papers were produced in accordance with the present disclosure and tested for various physical properties. The coated papers were produced from FSC-certified virgin wood pulp fibers (e.g., softwood fibers) and had a basis weight of approximately 60 g / m 2The cellulose layer contained a wet-laid web of 1000 sachets per 1000 sachets. One side of the cellulose layer was coated with a barrier coating composition containing dairy protein to form a barrier coating. The barrier coating composition was prepared by mixing dairy protein granules with cold water and stirring for 2 hours to obtain a homogeneous coatable solution. The dry content of the barrier coating composition was 15% dairy protein. The basis weight of the barrier coating was approximately 10 g / m 2 The coated paper further had a heat-sealable coating applied over the barrier coating. The heat-sealable coating was a combination of thermoplastic polysaccharides derived from corn agricultural waste and soy wax, and had a basis weight of approximately 10 g / m. 2 The following results were obtained:

[0162] [Table 1]

[0163] These and other modifications and variations to the present invention may be made by those skilled in the art without departing from the spirit and scope of the invention, which is more particularly set forth in the appended claims. It should be further understood that aspects of the various embodiments may be interchanged in whole or in part. Furthermore, those skilled in the art will appreciate that the foregoing description is illustrative only and does not limit the invention, as further set forth in the appended claims.

[0164] The following items are also part of this disclosure: [Item 1] providing a cellulose layer; applying to one side of the cellulose layer an aqueous solution or dispersion of a component of plant or animal origin; drying the applied aqueous solution or dispersion to form a barrier coating on the cellulose layer; applying an aqueous dispersion or emulsion of a coating composition comprising a wax onto the barrier coating; and drying the aqueous dispersion or emulsion to form a heat-sealable coating on the barrier coating. A method for producing coated paper, comprising: [Item 2] The method of item 1, wherein the cellulose layer is subjected to a step of compressing the cellulose layer in the machine direction before coating to provide an extensible cellulose layer. [Item 3] The method according to Item 2, wherein the cellulose layer is compressed in the longitudinal direction by subjecting it to a creping process. [Item 4] The method according to Item 3, wherein in the step of creping the cellulose layer, the cellulose layer is moving on a crepe cylinder, removed by a doctor blade, and sent to a transfer device through the surface of the doctor blade, and the creping is controlled by slowing the speed of the transfer device by 10 to 50% relative to the crepe cylinder. [Item 5] The method according to Item 2, wherein the step of compressing the cellulose layer in the longitudinal direction is carried out in a Clupak tensioning unit including a cylinder, a nip bar, a gap between the cylinder and the nip bar, and a rubber band disposed in the gap. [Item 6] The method according to any one of items 1 to 5, wherein a barrier coating and a heat-sealable coating are formed on both sides of the cellulose layer. [Item 7] The method according to any one of items 1 to 5, wherein the barrier coating and the heat-sealable coating are formed on only one side of the cellulose layer. [Item 8] The method according to any one of Items 1 to 7, wherein at least one side of the cellulose layer is subjected to an impregnation step before coating. [Item 9] The method according to Item 8, wherein the cellulose layer is impregnated with at least one compound selected from the group consisting of wax, polyester, polysaccharide, polysaccharide ester, polysaccharide ether, polysaccharide ether ester, glycerol, polyethylene glycol, polyvinyl alcohol, a softener, and an inorganic filler. [Explanation of symbols]

[0165] 10 Coated Paper 12 Cellulose layer 14 Barrier Coating 16 Heat-sealable coatings 18 Outer Surface 50 packages 52 Bottom 54 sides 56 Upper 60 Sealed Edges

Claims

1. a cellulose layer having a first surface and a second, opposing surface; a barrier coating applied to at least the first surface of the cellulose layer, the barrier coating comprising a component of plant or animal origin; and a heat-sealable coating applied over the barrier coating, the heat-sealable coating comprising a wax; Coated paper including.

2. 2. Coated paper according to claim 1, wherein the plant or animal derived component is water soluble or water dispersible, preferably water soluble.

3. 3. The coated paper of claim 1, wherein the plant or animal-derived component is amorphous.

4. 4. Coated paper according to any one of claims 1 to 3, wherein the component of plant or animal origin is a milk protein.

5. 5. The coated paper of claim 1, wherein the barrier coating is free of sugar fatty acid esters.

6. The barrier coating has a thickness of at least about 10 g / m ２ , and about 25 g / m ２ Below, for example, about 20 g / m ２ For example, about 18 g / m ２ 6. Coated paper according to any one of claims 1 to 5, having a basis weight of:

7. 7. Coated paper according to any one of claims 1 to 6, wherein the barrier coating consists of the plant or animal derived component, a polyvinyl alcohol polymer, and optionally a filler.

8. 8. Coated paper according to claim 7, wherein the barrier coating consists of 10% to 50%, for example 10% to 20%, by weight of the plant or animal derived component, and the remainder being a polyvinyl alcohol polymer.

9. 7. Coated paper according to any one of the preceding claims, wherein the barrier coating further comprises a polyvinyl alcohol polymer and / or nanocrystalline cellulose.

10. The coated paper has a thickness of about 10 g / m ２ / Moisture vapor transmission rate (MVTR) of less than 24 hours, and approximately 2 cm ３ / m ２ 10. The coated paper of claim 1, which exhibits an oxygen transmission rate (OTR) of less than 1 / 24 hours.

11. The coated paper of any one of claims 1 to 10, wherein the coated paper is calendered.

12. 12. Coated paper according to any one of the preceding claims, wherein the wax is a vegetable wax.

13. 13. The coated paper according to claim 12, wherein the vegetable wax is one or more selected from the group consisting of candelilla wax, carnauba wax, rice bran wax, soy wax, sugarcane wax, sunflower wax, pea wax, coconut wax and palm wax, preferably soy wax.

14. 14. The coated paper of claim 1, wherein the heat-sealable coating further comprises a polymer selected from the group consisting of polyesters, polysaccharides, polysaccharide esters, polysaccharide ethers, polysaccharide ether esters, and latex polymers.

15. 15. The coated paper of claim 14, wherein the polymer is a thermoplastic starch.

16. 16. The coated paper of any one of claims 1 to 15, wherein the coated paper passes the compostability test EN 13432:2001.

17. 17. The coated paper of any one of claims 1 to 16, wherein the coated paper is free of petroleum-based synthetic polymers.

18. 18. The coated paper of any one of claims 1 to 17, wherein the coated paper does not include an adhesive layer between the barrier coating and the first side of the cellulose layer or between the barrier coating and the heat-sealable coating.

19. The basis weight of the heat-sealable coating is about 1 g / m ２ ~Approx. 25g / m ２ , for example, about 3 g / m ２ ~About 20g / m ２ , for example, about 4 g / m ２ ~Approx. 15g / m ２ 19. The coated paper of claim 1, wherein

20. The cellulose layer has a thickness of about 20 g / m ２ ~Approx. 100g / m ２ , for example, about 30 g / m ２ ~Approx. 70g / m ２ 20. The coated paper of claim 1 having a basis weight of

21. 21. The coated paper of any one of the preceding claims, wherein the cellulosic layer comprises wood pulp fibers, bast fibers, or a mixture thereof.

22. The coated paper has a thickness of about 25 g / m ２ ~Approx. 125g / m ２ , for example, about 35 g / m ２ ~Approx. 90g / m ２ , for example, about 40 g / m ２ ~about 80g / m ２ 22. The coated paper of claim 1, having a basis weight of

23. 23. Packaging comprising the coated paper of any one of claims 1 to 22.

24. providing a cellulose layer; applying to one side of the cellulose layer an aqueous solution or dispersion of a component of plant or animal origin; drying the applied aqueous solution or dispersion to form a barrier coating on the cellulose layer; applying an aqueous dispersion or emulsion of a coating composition comprising a wax onto the barrier coating; and drying the aqueous dispersion or emulsion to form a heat-sealable coating on the barrier coating. A method for producing coated paper, comprising:

25. 25. The method of claim 24, wherein the coated paper is a coated paper according to any one of claims 2 to 22.

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