Products, their uses, and methods

Abstract

According to one aspect of the invention, a product is provided comprising a fibrous structure comprising cellulosic and / or lignocellulosic fibrous material obtained by a moulding process and a coating, such as at least one coating layer on at least one surface of the fibrous structure, the coating being obtained by a dry coating process, preferably a powder coating process.

Description

[Technical Field]

[0001] The present invention relates to coated fiber structures, and more specifically to coated molded fiber structures comprising cellulose fibers and / or lignocellulose fibers. [Background technology]

[0002] Fiber structures and products containing cellulose fibers and / or lignocellulose fibers are manufactured, for example, by wet-laid, air-laid, or molding methods. Such fiber structures are widely used in packaging technologies, primarily as an alternative to plastic-based packaging.

[0003] It is known that various coating films, such as barrier coatings, are applied to packaging materials and containers made from cellulose fiber materials such as cardboard. The purpose of such coating films is often to adjust or enhance surface properties to match the fiber structure.

[0004] The application of barrier coatings typically needs to be carried out in a separate process after the actual manufacturing of the fibrous substrate. For example, food containers and packaging are currently made of paper or cardboard with a plastic or wax-based barrier coating on the food-contacting surface of the container, such as a laminated or extruded barrier coating made of polyethylene terephthalate or polyethylene.

[0005] Known coating films have many drawbacks, including adhesion of the coating film to the rest of the product, such as textile products, and degradation of the coating film's mechanical properties during drying and conversion steps in manufacturing, or during humidity changes in transport and storage. For example, the coating may shrink in a different way than the substrate to which it is applied. The shrinkage problem is particularly important when using bio-based, water-diluted coating compositions.

[0006] In general, aqueous coatings present many problems and requirements for fiber base materials, such as structural issues during rewetting and the need for redrying. Another problem is insufficient gas barrier performance against water vapor, oxygen and the like.

[0007] It is difficult to prepare a smooth coating on a three-dimensional base material or object by known methods, and in particular, it is difficult to uniformly disperse the coating material on the side walls and bottom of the object.

[0008] Furthermore, known deep drawing processes face challenges because laminated or coated base materials must be moldable by pressing and also have sufficient flexibility to prevent the coating from cracking during the process.

[0009] Known coating methods have difficulty producing three-dimensional base materials that combine both high barrier properties and good heat-sealing properties.

[0010] The object of the present invention is to solve at least some of the problems existing in the known art. Summary of the Invention

[0011] The present invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0012] According to a first aspect of the present invention, there is provided an article comprising a fiber structure containing cellulose and / or lignocellulose fiber material obtained by a molding process, and a coating such as at least one coating layer on at least one surface of the fiber structure, wherein the coating is obtained by a dry coating process, preferably a powder coating process.

[0013] Various embodiments of the first aspect may include at least one feature from the bulleted list below. ·The coating forms the uppermost layer or the lowermost layer of the article. ·The product comprises at least two coating layers located on different surfaces of a fiber structure, such as opposite sides of a planar fiber structure. ·The product further comprises an intermediate non-fiber layer between the coating and the fiber structure. ·The coating is applied to a curved or non-horizontal surface of the fiber structure. ·The coating is a non-fiber coating, and comprises or consists of a thermoplastic polymer material or a thermosetting polymer material such as polyolefin, polyester, polyethylene terephthalate (PET), polyhydroxyalkanoic acid, or polylactic acid. ·The coating comprises a non-fiber layer that comprises or consists of a thermoplastic biodegradable polymer material. ·The coating comprises at least 80 wt%, for example at least 90 wt% of a thermoplastic polymer material or a thermosetting polymer material. ·The coating comprises at least 20 wt%, for example at least 60 wt% of a bio-based material. ·The coating comprises less than 80 wt%, such as less than 40 wt% of fossil-derived material. ·The coating is a functional coating adapted to modify surface functional properties such as barrier properties, visual properties, functional properties, and / or tactile properties. ·The coating or a part thereof is adapted to enhance the barrier properties of the surface of the fiber structure, and the barrier properties include one or more of oil resistance, grease resistance, liquid resistance, water resistance, water vapor resistance, aroma resistance, gas resistance, oxygen resistance and flavor barrier. ·The coating is adapted to modify the hardness, microscopic roughness, macroscopic roughness, friction properties, tactile properties, or color of the surface of the fiber structure. ·The product has a dry basis weight in the range of 5 to 900 g / m 2 , for example in the range of 100 to 800 g / m 2 , in the range of 200 to 600 g / m 2 . ·The coating has a dry basis weight in the range of 2 to 80 g / m 2 , for example 10 to 35 g / m 2 . The coating thickness is at least 1 μm, for example, in the range of 2 to 50 μm, for example, 5 to 30 μm. • The fiber structure is substantially free of plastic materials and resins. The fiber structure is a multilayer fiber structure comprising at least a first fiber layer and a second fiber layer, each fiber layer comprising cellulose and / or lignocellulose fiber material. The product further comprises one or more inner fiber layers between the first fiber layer and the second fiber layer, each inner fiber layer comprising cellulose and / or lignocellulose fiber material, preferably mechanical pulp and / or waste paper such as CTMP or BCTMP. Cellulose and / or lignocellulose fiber materials comprise one or more of the following: bleached or unbleached chemical pulp, semi-chemical pulp, mechanical pulp, thermomechanical pulp, chemothermetic pulp, bleached chemothermetic pulp, recycled cellulose and / or lignocellulose fibers, fibrillated cellulose such as microfibrillated cellulose or nanofibrillated cellulose, nanocellulose, waste paper, cellulose by-products, regenerated cellulose fibers, and other cellulose materials including cellulose fibers or portions of cellulose fibers derived from perennial or annual plants. The fiber structure contains at least 50 wt% cellulose and / or lignocellulose fiber material, calculated relative to the total dry material. One or more fiber layers or the entire fiber structure are obtained by foaming, water forming, dip forming, vacuum forming, press forming, thermoforming, or dry forming, or a combination thereof. The fiber structure is a three-dimensional molded fiber structure obtained using a mold that includes at least one three-dimensional non-planar mold surface, and the fiber structure exhibits a three-dimensional shape that conforms to the shape of the three-dimensional non-planar mold surface. • The product or a part thereof has an overall shape suitable for holding liquid or fluid materials, such as the overall shape of a cup or bowl. The fiber structure is a multilayer fiber structure containing at least two fiber layers. • All fiber layers of the fibrous structure are obtained by a foaming method within a mold. • The dry coating includes a powder coating.

[0014] A second aspect of the present invention provides a method for using the product according to the first aspect as packaging or a container for food products such as dairy products, fish or meat products, or as packaging for pharmaceuticals or cosmetics, or as part thereof.

[0015] According to a third aspect of the present invention, the product according to the first aspect is provided for use in the preservation, handling, preparation, or cooking of food.

[0016] A fourth aspect of the present invention provides a method comprising the steps of: preparing at least one fiber composition comprising cellulose fibers and / or lignocellulose fibers and water; forming a fiber structure from the at least one fiber composition in a mold; and coating at least a portion of the fiber surface of the molded fiber structure by a dry coating method such as a powder coating method.

[0017] Various embodiments of the fourth aspect may include at least one feature from the following bulleted list. The forming step includes forming a three-dimensional fiber structure from the at least one fiber composition using a three-dimensional mold. The powder coating process includes electrostatically applying dry powder to the surface of a fibrous structure, and curing or melting the applied powder, preferably by contact or non-contact heating and / or hot pressing, to form a film. The coated fiber structure has a dry material content of at least 90%, for example, 90-96%. The coated fiber structure has a dry material content of at least 50%, for example, at least 60%, for example, at least 70%, for example, 50-99%. The dry powder comprises a pigment, a binder, and one or more additives, the additives of which may be selected from the group of resins and fillers, such as barite, silica, carbonates, silicates, aluminum hydroxide, and mixtures thereof. • The application includes spraying. The curing or melting includes contact or non-contact heating, hot pressing, IR curing or microwave curing, or any combination thereof, preferably including contact or non-contact heating to a temperature of at least 80°C, for example, at least 120°C, for example, at least 150°C. The curing or melting process involves contact with or non-contact heating at temperatures of 80 to 300°C, for example, 120 to 250°C. The formation includes water formation, foam formation, dip formation, vacuum formation, press formation, thermoforming, dry formation, or any combination thereof, preferably by foam formation. The method further includes, after the forming step and before coating, a step of dehydrating the structure and a step of hot pressing the dehydrated structure to obtain a molded three-dimensional fiber structure, the hot pressing of which a surface directly suitable for dry coating such as powder coating is produced. The fiber structure to be coated has a dry material content of at least 60%. After coating, the coated fiber structure is hot-pressed, for example, a second hot-press is performed. • The density of the fiber structure to be coated must be at least 700 kg / m³ 3 That is the case. The fiber structure is a multilayer fiber structure comprising at least two fiber layers. Each fiber layer of the fiber structure is obtained by foaming and forming the respective fiber composition in a mold. • The dry coating includes powder coating. [Effects of the Invention]

[0018] (Advantages of the present invention)

[0019] The present invention makes it possible to easily produce a smooth and uniform coating film on a fibrous substrate, particularly a three-dimensional fibrous substrate.

[0020] The present invention aims to prepare a good and smooth coating on a substrate, and makes it easier to obtain a sufficiently smooth substrate by a dry coating method such as a spray method.

[0021] The present invention may provide textile products with improved surface properties such as barrier properties, optical properties, visual properties, and / or tactile properties.

[0022] This can help avoid problems related to insufficient adhesion of coating films, particularly to adhesion to fibrous substrates.

[0023] Furthermore, it can avoid problems related to heat sealability, such as insufficient adhesion to the fibrous substrate.

[0024] Dry coatings, such as powder coating, can offer many advantages over wet coating processes. Powder coating compositions sprayed onto objects can be recovered and reused, potentially reducing waste and costs compared to wet coating processes. Once powder-coated objects have cooled, they can be stacked and pressed together without sticking. Powder coating processes are faster than wet coating processes. Powder-coated surfaces are generally less prone to cracking from impact or bending.

[0025] This invention can facilitate the use of bio-based raw materials in coatings or paints for molded textile products.

[0026] The present invention can enable the formation of dry coatings such as paints by various methods such as contact heating, oven heating, microwave heating, IR (infrared) heating, or any combination thereof.

[0027] This method can avoid problems associated with re-wetting the fibrous substrate and, more generally, can reduce the need for water (i.e., water consumption) compared to known aqueous coating methods.

[0028] In this method, the coating can be prepared in a step integrated into the existing manufacturing line, so a separate conversion step may not be necessary.

[0029] This method, particularly powder coating, can enable the application of functional materials such as thermal insulation materials to a surface.

[0030] This method makes it possible to manufacture molded textile products having a patterned surface.

[0031] This product may offer one or more of the following: high heat resistance, non-flammability, excellent shape conformability or dimensional stability, strength, functional material support, acid resistance, improved flexibility, improved gas barrier properties, improved water vapor barrier properties, or grease resistance and / or water resistance.

[0032] This product may be suitable for label packaging or temperature-controlled packaging.

[0033] The structure and products of the present invention can be used for packaging, serving, storing, and preparing any product containing oil and / or water, such as food, pharmaceuticals, and cosmetics. [Brief explanation of the drawing]

[0034] [Figure 1] This figure schematically shows a coated fiber structure according to at least some embodiments of the present invention. [Modes for carrying out the invention]

[0035] Unless otherwise stated herein or evident from the context, percentages referred to herein are expressed as weight percentages based on the total dry weight of each composition.

[0036] The dry substance content of a composition is usually expressed as a weight percentage based on the total weight of the composition.

[0037] In this context, "dry coating" usually refers to any suitable coating method in which the coating material is applied or deposited on a surface in a dry state, for example, as dry particles, dry powder, or dry paint.

[0038] In this context, "powder coating" usually refers to a coating method in which a substantially dry powder or dry paint is applied or deposited onto a surface, usually by electrostatic coating.

[0039] In this context, "coating" refers to a coating that may consist of one or more coating layers that may be formed by the same or different coating processes.

[0040] In the current context, "resistance," such as water resistance, means that the material or layer resists the penetration of the substance in question. In a preferred embodiment, the material or layer exhibits "repellency," such as water repellency, which means that the substance in question cannot easily penetrate the material or layer. In a more preferred embodiment, the material or layer exhibits "prevention," such as waterproofing, which means that the substance cannot penetrate the material or layer during normal use of the product containing the material or layer. In other words, resistance to the penetration of the substance in question increases in the order of "resistance" < "repellency" < "prevention."

[0041] Furthermore, in this context, the term "resistance" means "at least resistant," meaning the material or layer may even exhibit water repellency or waterproofing.

[0042] This invention provides novel molded and coated textile products. At least a portion of the products can be manufactured by a foam-based process. Foam formation has the advantage of enabling the manufacture of molded multilayer structures and the adjustment of the properties of individual layers.

[0043] According to the present invention, the product comprises a cellulose and / or lignocellulose fiber material, a fibrous structure obtained by a molding process, and a coating such as at least one coating layer on at least one surface of the fibrous structure, the coating being obtained by a dry coating process, preferably a powder coating process.

[0044] The coating may consist of a single coating layer, or it may consist of multiple coating layers, such as 2 to 10 overlapping coating layers.

[0045] The coating may form the topmost or bottommost exposed surface or layer of the product.

[0046] The coating may form a typically exposed non-fibrous layer, either the top or bottom layer of the product.

[0047] The product may include at least two coatings located on different surfaces of the fiber structure, such as opposite sides of the planar fiber structure or different sides of the three-dimensional structure. Each coating may consist of one or more coating layers.

[0048] The product may include at least two coating layers located on different surfaces of the fiber structure, such as the opposite side of the planar fiber structure or a different side of the three-dimensional structure.

[0049] The product may include an intermediate non-fibrous layer or fibrous layer between the coating and the fibrous structure, such as a primer layer or a pre-flame treatment layer.

[0050] In one embodiment, the product may have a surface-purifying layer between the coating and the fibrous structure.

[0051] The primer layer may be fabricated by nanotechnology or microstructuring techniques. For example, the primer layer may contain microfibrillated cellulose (MFC) or nanofibrillated cellulose (NFC).

[0052] The product may include a further coating in addition to the coating according to the present invention. The coating of the present invention may be manufactured by a dry coating process, but the final further coating may be manufactured by any means, for example, a wet coating process. The further coating may be located below or above the coating of the present invention manufactured by the dry coating process.

[0053] In one embodiment, a coating layer is applied to a curved or non-horizontal surface of a fibrous structure.

[0054] The coating or a portion thereof may include thermoplastic polymer materials or thermosetting polymer materials.

[0055] Typically, the coating is a non-fibrous layer and contains or consists of thermoplastic polymer materials or thermosetting polymer materials such as polyolefins, polyesters, copolyester elastomers, polyethylene terephthalate (PET), nylon, polyhydroxyalkanoates, or polylactic acid (PLA). Polyolefins may include polyethylene and / or polypropylene.

[0056] In some embodiments, the coating is a non-fibrous layer and comprises or consists of a thermoplastic biodegradable polymer material.

[0057] In some embodiments, the coating is a non-fibrous layer and comprises or consists of a thermoplastic bio-based or non-fossil-based polymer material.

[0058] In one embodiment, the coating layer comprises at least 50 wt%, for example, at least 80 wt%, or for example, at least 90 wt%, of a thermoplastic polymer material or a thermosetting polymer material.

[0059] The coating may comprise a functional layer adapted to modify the functional properties of a surface, such as barrier properties, optical properties, visual properties, and / or tactile properties.

[0060] The coating may be adapted to enhance the barrier properties of the surface of the fibrous structure. The barrier properties may include one or more of oil and grease resistance, liquid resistance, water resistance, water vapor resistance, aroma resistance, gas resistance, oxygen resistance, and flavor barrier.

[0061] For example, the coating may be adapted to change the hardness, microscopic roughness, macroscopic roughness, or friction properties of the surface of the fibrous structure.

[0062] In some embodiments, the coating may be used to provide visual and / or tactile effects to the surface, such as color, metallization effects, color swirls, waves, droplet-shaped protrusions, crater-shaped cavities, stripes of varying transparency, or 3D effects, for example for anti-counterfeiting or security purposes.

[0063] In some embodiments, the coating provides surface properties such as an artificial leather surface, a non-slip surface, or an embossed effect.

[0064] In yet another embodiment, the coating may provide a tactile finish layer, a layer capable of changing color by electrical or other physical stimuli, or a layer that provides a visual impression of reflectance or depth.

[0065] The dry basis weight of the product ranges from 5 to 900 g / m 2 , for example 100 to 800 g / m 2 , more preferably 200 to 600 g / m 2 .

[0066] The dry basis weight of the coating ranges from 2 to 80 g / m 2 , for example 2 to 35 g / m 2 , for example 10 to 30 g / m 2 .

[0067] In one embodiment, the coating thickness is at least 1 μm, and is in the range of, for example, 2 to 20 μm, for example, 5 to 10 μm.

[0068] The structure of the fiber structure according to several embodiments is described below.

[0069] Preferably, the fiber structure contains at least 30 wt%, for example, at least 50 wt%, for example, 50-95 wt%, of cellulose and / or lignocellulose fiber material, calculated relative to the total dry material.

[0070] Preferably, the fibrous structure is substantially free of plastic materials and resins.

[0071] The fiber structure can be a single-layer fiber structure.

[0072] Alternatively, the fiber structure may be a multilayer fiber structure. The multilayer fiber structure comprises at least two fiber layers, for example, a first fiber layer and a second fiber layer, each fiber layer comprising cellulose and / or lignocellulose fiber material.

[0073] The product may further comprise one or more inner fiber layers between the first fiber layer and the second fiber layer, each containing cellulose and / or lignocellulose fiber material.

[0074] The fiber composition of the layers may be different from each other, or they may be the same.

[0075] The fibrous structure to be coated, or the layer of the fibrous structure to be coated, may contain additives such as pigments and / or fillers suitable for facilitating the dry coating process. For example, such additives may increase the moisture content, smoothness, and / or surface energy of the structure or layer to be coated. The fibrous layer containing additives may have a density of 30-600 g / m². 2 For example, 30-400 g / g / m 2 It may have a basis weight within the range of [specified range].

[0076] By creating a multilayer fiber structure, it becomes easier to adjust the compressibility of the structure, which can be advantageous from the perspective of dry coating processes.

[0077] Cellulose and / or lignocellulose fiber materials may include one or more of the following: chemical wood pulp, semi-chemical wood pulp, mechanical wood pulp, thermomechanical wood pulp, chemothermetic wood pulp, bleached chemothermetic pulp, bleached semi-chemical pulp, crushed wood pulp, pressure crushed wood pulp, crushed stone pulp, recycled cellulose and / or lignocellulose fibers, fibrillated cellulose such as microfibrillated cellulose or nanofibrillated cellulose, nanocellulose, waste paper, cellulose by-products, regenerated cellulose fibers, and other cellulose and / or lignocellulose materials containing cellulose fibers or portions of cellulose fibers.

[0078] The pulp may be bleached, unbleached, or a mixture of both.

[0079] The pulp may be refined, unrefined, or a mixture of both.

[0080] Chemical pulp may be obtained from any chemical pulping method, such as the sulfate method, the sulfite method, or the organosolve method.

[0081] Chemical pulp may include bleached chemical pulp.

[0082] Mechanical pulp can be obtained from any mechanical pulping process, including mechanical pulp, thermomechanical pulp (TMP), chemothermetic pulp (CTMP), bleached chemothermetic pulp (BCTMP), semichemical pulp, groundwood pulp (GW), pressure groundwood pulp (PGW), stone groundwood pulp (SGW), and combinations thereof.

[0083] Waste paper may include trimmed waste paper.

[0084] Cellulose fiber materials and / or lignocellulose fiber materials may contain non-wood pulp.

[0085] In one embodiment, pulp may be produced from broad-leaved trees such as birch trees (e.g., birch or poplar), willow trees, eucalyptus, mixed tropical broad-leaved trees or pine, or any combination thereof. Pulp may also be produced from coniferous trees such as spruce or pine, or a combination thereof. Furthermore, pulp may also be produced from a combination of broad-leaved and coniferous trees.

[0086] In one embodiment, the pulp may be produced from any annual plant such as straw, reeds, flounder, bamboo, sugarcane, bagasse, or any grass.

[0087] In one embodiment, the cellulose and / or lignocellulose fiber material, or a portion thereof, comprises bleached hardwood chemical pulp and bleached chemothermetic pulp, such as 10-50 wt% of bleached hardwood chemical pulp and 50-90 wt% of bleached chemothermetic pulp, based on the total dry material.

[0088] Typically, one or more surface layers of a product may contain bleached chemical pulp, such as bleached hardwood chemical pulp or bleached birch chemical pulp.

[0089] In one embodiment, one or more inner fiber layers may contain or consist of mechanical pulp such as chemothermetic pulp (CTMP) or bleached chemothermetic pulp (BCTMP), and / or waste paper (e.g., 60-95 wt% BCTMP and 5-40 wt% waste paper of the total dry material).

[0090] In one embodiment, one or more inner fiber layers may include or consist of mechanical pulp such as chemothermetic pulp (CTMP) or bleached chemothermetic pulp (BCTMP). Preferably, the inner fiber layers are substantially free of waste paper.

[0091] In some embodiments, the cellulose and / or lignocellulose fiber material comprises virgin wood pulp, such as virgin bleached chemical pulp, which is substantially lignin-free, thereby making the product particularly suitable for cooking, heating, and safe food contact.

[0092] The advantage of virgin pulp is that it does not contain residual ink or other undesirable chemicals. Recycled waste often contains chemical and microbial contaminants, which can affect its safe use. When mixtures of chemicals and microorganisms leach from recycled materials, they can cause various adverse health and environmental effects. The toxicity of recycled materials and their emissions can increase not only due to the hazards of individual compounds but also due to interactions with other compounds and microbial products. Therefore, it is preferable in this invention to avoid using recycled materials.

[0093] The advantage of chemical pulps, such as bleached chemical pulp, is that they are virtually lignin-free. Pulps containing lignin can be susceptible to material aging and yellowing.

[0094] In some embodiments, the cellulose and / or lignocellulose fibrous material contains lignin in the form of a lignocellulose fibrous material, such as bleached or unbleached mechanical pulp. The present invention can benefit from the presence of lignin in the fibrous structure. Because there is a coating layer on top of the fibrous structure, the lignin-containing fibrous material or layer is ultimately separated from its surroundings, for example, food contents in packaging.

[0095] In one embodiment, the fibrous cellulose and / or lignocellulose fibrous material or a portion thereof comprises or consists of bleached coniferous chemical pulp.

[0096] In one embodiment, the fibrous cellulose and / or lignocellulose fibrous material or a portion thereof comprises or consists of bleached hardwood chemical pulp.

[0097] In one embodiment, the cellulose and / or lignocellulose fibrous material or a portion thereof comprises or consists of a mixture of bleached coniferous chemical pulp and bleached hardwood chemical pulp.

[0098] When manufacturing a molded fiber structure or a part thereof, any suitable molding method can be applied, such as injection molding, vacuum forming, compression molding, transfer molding, extrusion molding, blow molding, dip molding, rotational molding, foam molding, lamination, deep drawing, thermoforming, press forming, hydroforming, suction forming, closed mold forming, open mold forming, dry forming, foam forming, or a combination thereof.

[0099] In the current context, the terms "shaping" and "forming" can be used interchangeably.

[0100] The forming method may be complemented by additional processes such as various forming processes including, for example, in-mold drying, cold and hot pressing, calibration pressing, bending or shearing, or machining processes such as turning, drilling, forming, grinding, heat sealing, printing or finishing, cutting, or any combination thereof.

[0101] In a preferred embodiment, one or more fiber layers of the fiber structure, or the entire fiber structure, are obtained by foam formation, water formation, or wet formation in a mold, preferably by foam formation in a mold.

[0102] Preferably, all fiber layers of the product are obtained by foam formation in a mold.

[0103] The fiber structure may be a three-dimensional molded fiber structure obtained using a mold that includes at least one three-dimensional non-planar mold surface. In this case, the fiber structure exhibits a three-dimensional shape that conforms to the shape of the three-dimensional non-planar mold surface.

[0104] The product or a part thereof may have an overall shape suitable for holding liquids or fluid materials, such as the overall shape of a cup or bowl.

[0105] In one embodiment, the oil and grease resistance (OGR) of the product is measured in olive oil at 60°C according to ASTM F119 and is at a "moderate" or higher level, such as more than 10 minutes, typically from 10 minutes to 6 hours, and in one example more than 3 hours.

[0106] In one embodiment, the oil and grease resistance (OGR) of the product, measured by ASTM F119 in olive oil at 60°C, is at a "moderate" or higher level, such as more than 6 hours, typically 6 to 72 hours, and in one example more than 3 days.

[0107] In one embodiment, the moisture resistance of the product was measured under standard conditions of 23°C and 50%RH according to ISO 2528 and ASTM E96, at 25 g / m². 2 Less than / d, usually 100-250g / m 2 / d, for example 150g / m 2 This is a "moderate" or higher level, such as less than / d.

[0108] In one embodiment, the moisture resistance of the product is measured according to ISO 2528 and ASTM E96 under standard conditions of 23°C and 50%RH, and the water vapor transmission rate is at a level of "good" or higher, for example, 100 g / m². 2 Less than / d, usually 10-50g / m 2 / d, for example, 30g / m 2 It is less than / d.

[0109] The present invention can provide good gas barrier properties suitable for packaging, for example, refrigerated foods. In one embodiment, the oxygen permeability of the product is measured according to ASTM D-3985 under standard conditions of 23°C and 50% RH and is at a level of "good" or higher, for example, 100 cm³. 3 / m 2 Less than / d, usually 50-100cm 3 / m 2 / d range, or 50cm 3 / m 2It is less than / d.

[0110] Refrigerated foods are typically 40-60 cm 3 / m 2 A high oxygen barrier like / d is required. Refrigerated foods typically have a barrier of 1-1.5 cm. 3 / m 2 A water vapor barrier is required.

[0111] In one embodiment, the water absorption rate of the coated side or surface of the product is measured by ISO 535, by the Cobb value after 5 minutes, and is 100 g / m². 2 Less than 50-100g / m² 2 For example, 75g / m 2 This is a level of "moderate" or higher, such as "below" or "below."

[0112] In one embodiment, the water absorption rate of the coated side or surface of the product is measured by ISO 535, Cobb value after 5 minutes, and is 50 g / m². 2 Less than 5-50g / m² 2 For example, 15g / m 2 This is a level of "moderate" or higher, such as "below" or "below."

[0113] Preferably, the density of the coated fiber structure is calculated as dry solids weight / volume and is 300-1000 kg / m³. 3 For example, 350-800 kg / m 3 For example, 450-700 kg / m 3 For example, 500 kg / m 3 It is a larger range.

[0114] In one embodiment, the density of the coated fiber structure is calculated as dry solids weight / volume and is 700-1000 kg / m³. 3 For example, 750-950 kg / m 3 For example, 775-900 kg / m 3 For example, 800 kg / m 3 It is a larger range.

[0115] In some embodiments, the presence of a powder coating layer may result in the formation of a dense, closed structure or surface layer on top of the fibrous structure, so the density of the fibrous structure is 500 kg / m³. 3 It could be a relatively low value, such as less than or equal to.

[0116] In some embodiments, the density of the fiber structure is 800 kg / m³. 3 Less than, for example, 700 kg / m 3 Less than, for example, 600 kg / m 3 It may be less than.

[0117] Preferably, the surface smoothness of the fibrous structure to be coated is measured by the ISO 8791-2 bentosene method and is in the range of 50 to 3000 ml / min, for example 100 to 1000 ml / min, or for example 150 to 600 ml / min. The advantage of having a smooth surface is that powder coating by methods such as spraying is facilitated.

[0118] In one embodiment, the surface smoothness of the fibrous structure to be coated is measured by the ISO 8791-2 bentosene method and is in the range of 10 to 1000 ml / min, for example 20 to 500 ml / min, or for example 50 to 250 ml / min. Preferably, the surface smoothness of the fibrous structure to be coated is less than 400 ml / min. The advantage of having a smooth surface is that powder coating by spraying, for example, becomes easier.

[0119] The coated fibrous structure or a part thereof, for example, a fibrous layer of the fibrous structure, may contain one or more additives or chemical additives. In one embodiment, at least the coated surface layer or coated surface portion of the fibrous structure contains one or more chemical additives.

[0120] The coated fibrous structure or a part thereof, for example, the fibrous layer of the fibrous structure, may contain one or more additives such as talc, clay, calcium carbonate, and metal salt pigments, such as aluminum trihydrate, gypsum, silicates, silica compounds, and titanium dioxide; barrier agents, latex binders, water-soluble binders such as PVA (polyvinyl alcohol), starch, and CMC (carboxymethylcellulose); sizing agents such as AKD (alkyl ketene dimer or alkenyl ketene dimer), ASA (alkenyl succinic anhydride), and resins; and reinforcing agents such as CMC, MFC (microfibrillated cellulose), and NFC (nanofibrillated cellulose).

[0121] In one embodiment, the additive includes an enhancer such as CMC (carboxymethylcellulose), MFC (microfibrillated cellulose), NFC (nanofibrillated cellulose), or any combination thereof.

[0122] In one embodiment, the additive includes an additive such as a pigment that can enhance the smoothness of the surface to be coated.

[0123] In one embodiment, the surface to be coated becomes more hydrophobic by incorporating appropriate additives, such as surface sizing agents like alkyl ketene dimers (AKD) and / or starch, into the fibrous structure or its surface.

[0124] In one embodiment, the hydrophilicity of the coated surface is enhanced by incorporating appropriate additives, such as hydrophilizing agents, into the fiber structure or its surface.

[0125] The amount of additive can range from 0.01 to 30 wt%, calculated from the total dry material, such as 0.01 to 10 wt%, 0.1 to 8 wt%, or 1 to 5 wt%.

[0126] In one embodiment, the amount of additive may be in the range of 0.01 to 40 wt% calculated from the total dry material.

[0127] Additives or chemicals may be added to the fibrous raw material or slush at concentrations of, for example, 0.5-15%, 0.8-10%, or 2-10% before the forming step, preferably before the foaming step, or they may be added to the foam to be mixed with the fibrous slush before the forming step, preferably before foaming.

[0128] In one embodiment, at least one of the fibrous structure or its fibrous layers contains 0.1 to 5 wt% talc.

[0129] In one embodiment, at least one of the fibrous structure or its fibrous layers contains 0.1 to 5 wt% clay.

[0130] In one embodiment, at least one of the fibrous structure or its fibrous layers contains 0.1 to 5 wt% calcium carbonate.

[0131] In one embodiment, at least one of the fibrous structures or fibrous layers comprises a barrier agent selected from the group consisting of dispersion polymers, polyolefins, polyesters, other thermoplastic polymers, biodegradable polymers such as polylactic acid, starch and its derivatives, plastomers, elastomers, ethylene vinyl alcohol, and any derivatives, copolymers, and mixtures thereof.

[0132] In one embodiment, at least one of the fibrous structures or fibrous layers contains a barrier agent, such as a dispersed polymer barrier agent, in an amount of 0.1 to 10 wt%, such as 0.1 to 5 wt%. Such a barrier agent typically provides barrier properties throughout the structure of the fibrous layer.

[0133] In one embodiment, at least one of the fibrous structures or fibrous layers contains 0.1 to 5 wt% of a polymer latex binder such as styrene-butadiene latex, styrene-acrylate latex, or polyvinyl acetate latex.

[0134] In one embodiment, at least one of the fibrous structure or its fibrous layers contains 0.1 to 5 wt% polyvinyl alcohol (PVA).

[0135] In one embodiment, at least one of the fibrous structures or fibrous layers contains 0.1 to 20 wt% of starch, such as 0.1 to 5 wt%.

[0136] Starch can be natural, modified, cooked, or swollen cationic starch.

[0137] In one embodiment, at least one of the fibrous structure or its fibrous layers contains 0.1 to 5 wt% carboxymethylated cellulose (CMC).

[0138] In one embodiment, at least one of the fibrous structure or its fibrous layers contains 0.1 to 20 wt% of a mineral filler.

[0139] In one embodiment, at least one of the fibrous structure or its fibrous layers contains 0.1 to 20 wt% of pigment by the total dry material. Preferably, the coated surface layer or surface portion contains 0.1 to 20 wt% of pigment.

[0140] In one embodiment, at least one of the fibrous structures or fibrous layers contains 0.1 to 20 wt% of a reinforcing additive such as microcrystalline cellulose (MCC), nanocellulose, or other reinforcing cellulose.

[0141] In one embodiment, the fibrous structure or at least one of its fibrous layers comprises a reinforcing additive such as microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), or other reinforcing cellulose, or any combination thereof.

[0142] In one embodiment, the amount of the reinforcing additive is 0.1 to 20 wt%.

[0143] Preferably, at least one of the fiber structure or its fiber layers contains less than 10 wt%, for example less than 5 wt%, or less than 2 wt%, of wax, plastic, and fluorine chemicals. In one embodiment, at least one of the fiber structure or its fiber layers contains less than 2 wt% of wax. In one embodiment, at least one of the fiber structure or its fiber layers contains less than 2 wt%, for example less than 1 wt%, of plastic. In one embodiment, at least one of the fiber structure or its fiber layers contains less than 2 wt%, for example less than 1 wt%, of fluorine chemicals.

[0144] In some embodiments, the product is substantially free of waxes, plastics, fluorochemicals, and especially plastics.

[0145] For products intended for food packaging, additives and foaming chemicals may be selected from all additives approved for use in food-contact materials or packaging. "Food-contact materials" refers to all materials and articles intended to come into contact with food, such as packaging and containers.

[0146] The amount of barrier additive in the fiber structure or a part thereof may be in the range of 1 to 10 wt%, for example, 5 to 8 wt%, calculated from the total dry weight of the fiber layer.

[0147] In some embodiments, the coating or a portion thereof may impart a first type of barrier property, and the underlying fibrous structure may impart a second type of barrier property distinct from the first type. For example, the coating or a portion thereof may impart water barrier properties, and the fibrous structure may impart oil and / or grease barrier properties.

[0148] In some embodiments, the coating or a portion thereof may enhance barrier properties, such as oil and / or grease barrier properties, provided by the underlying fibrous structure.

[0149] If a product includes an additional coating below or on top of a coating prepared by a dry coating process, such additional coating may also impart barrier properties. For example, a coating prepared by a dry coating process may impart oxygen barrier properties, while an additional coating prepared by a wet coating process may impart different barrier properties, such as water barrier properties.

[0150] The coating structure of the present invention can be used in food contact materials and articles.

[0151] In one embodiment, the product complies with Regulation (EC) No. 1935 / 2004.

[0152] The current structure and products have many potential applications beyond food contact, or alternatively, in many other fields.

[0153] In one embodiment, at least one fiber layer contains a sizing agent such as a modified rosin, wax, oil, or polymer. The advantage of using a sizing agent is that it can reduce the undesirable absorption of liquids and / or water and / or moisture into the foam-forming structure. This improves the moisture or water resistance of the product.

[0154] An example of a wax is alkyl ketene dimer (AKD). An example of an oil is alkenyl succinic anhydride (ASA). An example of a polymer sizing agent is styrene acrylate emulsion (SAE).

[0155] The preferred sizing agent is AKD or a similar wax.

[0156] Sizing agents applicable to some embodiments of the present invention may be cationic or anionic surface sizing agents, such as rosin-based sizing agents. In addition to these, or as an alternative, several reactive sizing agents, such as alkyl ketene dimers (AKDs), may be used as surface sizing agents.

[0157] Suitable cationic sizing agents include cationic starches and starch derivatives, as well as corresponding carbohydrate-based natural polymers. Among synthetic polymers, for example, styrene / acrylate copolymers (SA), polyvinyl alcohol, polyurethanes, and alkylated urethanes may be used.

[0158] Suitable anionic sizing agents may include anionic starches and starch derivatives, as well as corresponding carbohydrate-based natural polymers such as carboxymethylcellulose and its salts, and alkylcelluloses such as methylcellulose and ethylcellulose. Synthetic polymers may include styrene / maleic acid copolymer (SMA), diisobutylene / maleic anhydride, styrene acrylate copolymer, acrylonitrile / acrylate copolymer, polyurethanes containing the same chemical functional groups, and similar latex products.

[0159] In one embodiment, the sizing agent includes an alkyl ketene dimer (AKD).

[0160] In one embodiment, additives such as pigments, binders, and sizing agents are adapted for oven-safe products.

[0161] In some embodiments, the product or fiber structure may comprise only one fiber layer.

[0162] In some embodiments, the product may comprise 1 to 20 fiber layers, such as at least 2 fiber layers and at least 3 fiber layers.

[0163] In some embodiments, the product includes an intermediate layer, such as a pre-coating layer, between the coating and the fibrous structure.

[0164] The intermediate layer may include or consist of MFCs, PVA, CMCs, starch, talc, or a combination thereof.

[0165] The advantage of using an intermediate layer between the coating and the fibrous structure is that it can improve the adhesion and functionality of the coating.

[0166] The method of the present invention makes it possible to obtain a smooth surface on the fiber structure to be coated, and facilitates coating onto the fiber structure, particularly the application or adhesion of powder coating layers.

[0167] Coatings and any intermediate layers are typically applied after the forming stage, preferably after the hot pressing stage.

[0168] One or more intermediate layers may have already been prepared prior to the hot pressing step, for example, in a forming or molding step.

[0169] In one embodiment, the coating is applied before hot pressing or between two hot pressing stages. Therefore, as a result of the heat applied during hot pressing, the coating layer forms a film, usually a smooth and continuous film. Thus, the heat melts the powder coating and converts it into a film. This method may allow for the preparation of embossed or other textured structures on the exposed surface of the coating, typically forming the outermost surface of the product.

[0170] A hot pressing step including at least two hot pressing steps can smooth the outer surface of the final product. Preferably, all outer or exposed surfaces of the final product can be smoothed.

[0171] For example, in the first hot-pressing step, water generated in the forming step can be removed, and in the subsequent second hot-pressing step, a film structure can be generated from the applied powder coating.

[0172] Figure 1 schematically shows a coated fiber structure according to at least some embodiments of the present invention. This structure comprises a first fiber layer 1, a second fiber layer 2, and an inner fiber layer 3 between the first fiber layer 1 and the second fiber layer 2. Furthermore, this structure comprises an intermediate layer 4 and a coating 5 on top of the first fiber layer. In other embodiments, the intermediate layer 4 may be absent. In some embodiments, this structure may comprise a second coating (not shown) on the opposite side of the fiber layer below the second fiber layer 2. Between such a second coating and the second fiber layer 2, an intermediate layer may be applied in a manner similar to that between the (first) coating 5 and the first fiber layer 1.

[0173] In another embodiment, the product comprises a single fiber layer, such as a first fiber layer 1, a coating 5, and optionally an intermediate layer 4.

[0174] In yet another embodiment, the product does not include any intermediate layer.

[0175] In some embodiments, the product does not include an inner fiber layer. In other embodiments, the product includes one, two, or three inner fiber layers between the first fiber layer 1 and the second fiber layer 2.

[0176] It is preferable that the multilayer fiber structure is obtained such that all fibers included in the final structure, and the fiber structure that is typically coated, undergo a foam formation process.

[0177] The advantage of foam molding is that it allows for the production of lighter and bulkier products. Furthermore, it enables the achievement of a more homogeneous formation. By using foam, multilayer fiber structures can be easily manufactured in a batch process. That is, all fiber layers can be formed in the same mold to form a multilayer stack within the mold, and that stack can then be hot-pressed.

[0178] The advantage of dewatering the entire multilayer fiber structure within the same mold is that, compared to dewatering each layer individually, the bonds between layers may be strengthened even during the dewatering process.

[0179] In some embodiments, in addition to the foam-forming layer, the final product may further comprise a water-forming layer as part of the fibrous structure. Such one or more water-forming layers may be formed by a separate process and bonded to the foam-forming layer or foam-forming multilayer structure by hot pressing. An advantage of water forming is the ease of preparing flat or planar structures. In the water forming method, individual fibrous layers are typically formed independently of each other and removed from the mold. Separate molds may also be used. After removal from the mold, the fibrous layers can be stacked and bonded to each other and / or to other layers by hot pressing.

[0180] In one embodiment, the fiber structure comprises several fiber layers, which are prepared by a water formation process, bonded together, and optionally added to and coated with at least one foam-forming fiber layer to form a fiber structure.

[0181] In some embodiments, the fibrous structure may be formed by the water formation method alone.

[0182] In one embodiment, the fibrous structure comprises one or more internal fibrous layers prepared by a foaming process.

[0183] In one embodiment, the entire fiber structure is prepared by a foaming process.

[0184] Preferably, the fiber structure is a three-dimensional molded multilayer fiber structure obtained by using a mold that includes at least one three-dimensional non-planar mold surface, wherein the fiber structure exhibits a three-dimensional shape that matches the shape of the three-dimensional non-planar mold surface.

[0185] For example, the product may take the form of a cup, plate, bowl, pot, clamshell, or tray.

[0186] Typically, the product is a package or container for food or liquids, or a food or liquid serving product such as a beverage cup, food tray, or plate.

[0187] This product can be used for packaging, storing, cooking, and / or heating food, liquids, or beverages. Examples include packaging frozen foods intended for heating, packaging yogurt, and trays for fresh meat and fish.

[0188] For example, this product can be used for packaging various industrial products such as food, for packaging trays for cold cuts of meat, fish, cheese, and other sliced ​​foods, and for the storage and transport of items such as food, beverages, pharmaceuticals, cosmetics, and materials sensitive to moisture and oxygen.

[0189] In some embodiments, the product can be used as a heat-resistant cushioning material or a heat-resistant shielding material.

[0190] More generally, this product can be used for packaging and storing any product that contains oil or moisture.

[0191] In one example, the product is cosmetic packaging.

[0192] In one example, the product is pharmaceutical packaging.

[0193] This product may be used as packaging for food or liquids, as a serving product for food or liquids, as a baking product, or as part of such products.

[0194] Next, we will describe the manufacture of dry-coated fiber structures according to several embodiments.

[0195] This method includes providing at least one fiber composition comprising cellulose fibers and / or lignocellulose fibers and water. A fiber structure is formed from the at least one fiber composition in a mold. Subsequently, a coating layer is applied to at least a portion of the surface of the molded fiber structure. The coating layer is applied by a dry coating method such as powder coating.

[0196] Preferably, the forming step includes forming a three-dimensional fiber structure from the at least one fiber composition using a three-dimensional mold.

[0197] The powder coating process may include electrostatically applying a dry powder, such as a dry composition or powder coating, to the surface of a fibrous structure, and then preferably curing, melting, or forming a film from the applied powder by heating.

[0198] Dry compositions, such as thermoplastic powder coating compositions, may be applied by using an electrostatic spraying device, or by other suitable means or methods, such as using a fluidized bed coating or a mini-coater.

[0199] Dry compositions such as powder coatings may typically contain particles having an average particle size in the range of 2 to 50 μm.

[0200] In some embodiments, the powder coating has a softening temperature T in the range of 70-90°C. g It has a melting point in the range of 120-180°C and typically hardens at a temperature of 180-220°C.

[0201] In some embodiments, the drying composition, such as a powder coating, is cured at a temperature of 180-240°C.

[0202] Advantageously, the coating includes a thermoplastic powder coating, which may only require sufficient heat and time to melt the powder into a smooth, continuous film.

[0203] Various properties of the coating, such as adhesion, lubricity, flexibility, and elongation, can be optimized for specific applications. In the case of thermoplastic coatings, once the powder is applied to an object or surface, it can inherently exhibit these properties without requiring further curing or crosslinking.

[0204] In one embodiment, the coated fiber structure has a dry material content of at least 60%, for example, at least 70%, for example, 60-80%.

[0205] In one embodiment, the coated fiber structure has a dry material content of at least 60%, for example, 60-95%.

[0206] In one embodiment, at least a portion of the surface to be coated is substantially dry. For example, the top layer of the fibrous structure to be coated can be substantially dried by heating or other means.

[0207] The dry powder applied to the surface may contain a pigment and one or more additives, which may be selected from the group consisting of barite, silica, carbonate, silicate, aluminum hydroxide, latex, nylon, polyethylene, polyester, polypropylene, polyvinyl chloride and other resins, binders, fillers, and mixtures thereof.

[0208] In one embodiment, the coating layer is generated on the surface by spraying. The present invention may enable the application of a powder coating by spraying directly onto a vertical or curved surface.

[0209] In some embodiments, while the coating layer is being applied, the fibrous structure to be coated is placed near or on an article made of a metallic material, such as a metal foil sheet. In this way, the fibrous structure acquires a sufficient charge.

[0210] Other means for generating the coating layer may be used, such as separately preparing a coating film by a powder coating method and then attaching or pressing the prepared coating film onto the desired surface of the molded fiber structure.

[0211] Curing or melting or film production may include contact or non-contact heating, hot pressing, IR curing or microwave curing, or any combination thereof, preferably heating to a temperature of at least 120°C, for example, at least 150°C.

[0212] In one example, the film preparation step includes a first step of melting a coated dry composition, such as a dry powder coating or dry particles, by IR melting, and a second step of finally curing or preparing the film by one or more subsequent hot pressing steps.

[0213] Preferably, the film manufacturing step includes or consists of contact heating, such as hot pressing.

[0214] In one embodiment, the film preparation steps, such as contact heating, have a total duration of less than 2 minutes, for example, less than 1 minute, and can be divided into multiple steps as needed.

[0215] Pressure may be applied during a curing, melting, or film preparation step, such as one or more hot pressing steps.

[0216] In film manufacturing steps, such as the hot pressing step, heat may be applied to the coating layer from one or both sides of the coating. For example, heat may be applied from below through the fibrous structure or from above the coating. Different heating profiles may be applied from each side of the coating.

[0217] In hot pressing, the temperature on at least one side of the structure being hot-pressed is typically higher than room temperature, for example, at least 50°C, for example at least 100°C, for example in the range of 150-240°C.

[0218] For example, the temperature applied to the coating can reach at least 200°C.

[0219] For example, the temperature applied from below the coating through the fibrous structure may be less than 100°C.

[0220] Hot pressing allows for the application of higher pressure.

[0221] Alternatively or additionally, a pressure below atmospheric pressure, for example, 60 kPa or less, may be applied in the hot press.

[0222] A hot press may include two or more consecutive hot press steps. The hot press may have a total duration of less than two minutes, for example, less than 30 seconds, or for example, less than 20 seconds.

[0223] During hot pressing, heat is applied from one or both sides of the material being pressed. In one embodiment, heat is applied from only one side.

[0224] For example, a hot press may include two hot press steps in which heat is applied from the same side, or it may include two hot press steps in which heat is applied from different sides.

[0225] Hot pressing may include impulse drying.

[0226] The coating step may be performed before all hot pressing steps. In this case, the dry material content of the fiber structure to be coated may be at least 30%.

[0227] The coating step is preferably performed between the two hot pressing steps, in which case the dry material content of the fiber structure to be coated may be at least 60%.

[0228] The coating step may be performed after all the hot pressing steps. In this case, the dry material content of the fiber structure to be coated may be at least 80%, for example, at least 90%.

[0229] In some embodiments, the final coating thickness is less than 100 μm, for example, less than 70 μm.

[0230] Next, embodiments relating to the foam formation of the fibrous structure will be described in more detail.

[0231] In one embodiment, the coated fibrous structure or a portion thereof is obtained by utilizing foam formation.

[0232] In some embodiments, a fibrous structure or at least one of its fibrous layers may be obtained by a method comprising the steps of: providing a fibrous slush containing fibers; purifying the fibers of the fibrous slush and / or adding a barrier agent to the fibrous slush; preparing the fibrous slush into a foamed composition; forming the foamed composition in a mold, such as by molding; dehydrating; and hot pressing.

[0233] This method first provides a foamed composition comprising fibers, water, air, and one or more foaming chemicals. The foam may further contain fillers, additives, pigments, binders, enhancers, barrier dispersants, and sizing agents.

[0234] The foaming chemicals used, such as surfactants, can be nonionic, anionic, cationic, or amphoteric. An appropriate amount of surfactant is approximately 150–1000 ppm by weight. Examples of anionic surfactants include alpha-olefin sulfonates, while an example of a nonionic surfactant is PEG-6 lauramide. Specific examples include sodium dodecyl sulfate (SDS), Tween 20, and mixtures thereof. Tween 20 contains at least 40 wt% lauric acid, with the remainder consisting mainly of myristic acid, palmitic acid, and stearic acid.

[0235] Preferably, the foaming chemical contains or consists of at least one anionic surfactant, such as SDS. Powder coating may be particularly advantageous when using anionic surfactants that can impart a low surface energy to the surface being coated.

[0236] Typically, the size (diameter) of bubbles in a foam is approximately 10-300 μm, for example, 20-200 μm, and usually about 20-80 μm.

[0237] In one embodiment, the bubble size (bubble diameter) within the bubble is at least 100 μm, for example, 100 to 200 μm.

[0238] In one embodiment, a composition suitable for foaming is obtained by mixing a fibrous slush having a viscosity (amount of fiber relative to the weight of the slush) of about 0.5 to 7% by weight with foam formed from water and a surfactant, and the air content is, for example, 20 to 80%, 50 to 70% by volume, etc., resulting in a foamed fibrous slush with an air content of about 10 to 90% by volume, in this case about 0.1 to 3% by weight of fiber.

[0239] In one embodiment, the molded multilayer fiber structure is obtained by a method comprising the steps of: forming a molded multilayer foam structure from at least one foam fiber composition comprising cellulose fibers, water, air, and a foaming agent, and optionally a barrier agent; dehydrating the structure, preferably by applying a vacuum; and hot pressing the dehydrated structure to obtain a molded multilayer fiber structure. At least one of the fiber layers of the multilayer fiber structure exhibits barrier properties substantially throughout its structure.

[0240] In this specification, "forming" refers to the process of giving a foamed composition a shape, such as a three-dimensional shape, within a mold.

[0241] In a preferred method, the foamed fiber composition is supplied to a mold. The mold typically comprises a cavity or internal space defined by the inner surface of the mold. Within the cavity, the supplied foamed composition is molded.

[0242] A foamed composition can be supplied to a mold to provide a certain amount of the foamed composition, for example, a layer of the foamed composition, on at least one inner surface of the mold. This layer is typically non-planar and exists on the inner surface of the mold, and can be understood as a thickness of the foamed composition that conforms to the shape of the surface, for example, a substantially constant thickness.

[0243] Typically, the molding step involves pressurizing the fiber composition within the internal space of the mold by bringing parts of the mold closer together.

[0244] The step of forming a multilayer foamed fiber structure may include supplying a first fiber composition in foam form to a mold and molding the first fiber composition in the mold to prepare a first foamed fiber layer. The process is then continued by supplying a second fiber composition in foam form to the mold without removing the first fiber layer from the mold, and molding the second fiber composition in the mold to prepare a second foamed fiber layer. As a result, a two-layer foamed fiber structure is obtained in the mold.

[0245] Unless otherwise specified, "mold portion" refers to the portion of the mold that defines the internal space and therefore contributes to the molding of the foamed fiber composition.

[0246] The second foam fiber layer is supplied and may be located above or below the first foam fiber layer in the mold. The supply step may be performed in either order, and either the first or second layer may be formed in the mold first.

[0247] It is also conceivable that the fiber structure is obtained by using separate molds to prepare the first and second foamed fiber layers, and that the obtained first and second fiber layers are joined together in the hot press step.

[0248] In one embodiment, the supply to the mold includes supplying a foamed fiber composition in foam form into the internal space or internal volume of the mold, the internal space being limited by the inner surface of the mold.

[0249] Preferably, the application of vacuum in the dehydration step is possible.

[0250] The final multilayer foamed fiber structure is removed from the mold by opening the mold.

[0251] It is preferable that the distance between each part of the mold can be adjusted during the supply and molding of the foam composition.

[0252] Before supplying a second fiber composition or the like into the mold, it is usually necessary to move the mold components apart from each other to expand the internal space of the mold. The volume of the internal space can be reduced or increased to mold the already supplied foam and to create space for the foam to be supplied next.

[0253] When adjusting the entire internal volume of a mold, some parts of the mold may remain stationary while others move.

[0254] In one example, during the approach or enlargement, one or more parts of the mold remain stationary, while one or more other parts of the mold move.

[0255] For example, a mold may comprise two sub-molds, such as two half-molds, arranged facing each other and movable relative to one another. The sub-molds can be brought close together to form a fiber structure. The sub-molds can be moved apart to enlarge the internal space, or they can be moved further apart to open the mold and remove the formed fiber structure from the mold.

[0256] In one example, a fibrous structure may be obtained by using a mold comprising two parts, namely a negative mold and a positive mold. These molds may be positioned facing each other so as to enclose an internal space between the two parts, also called a molding space or molding cavity. The composition to be molded or formed is supplied to the molding space, and the negative mold and / or positive mold are brought closer to each other to give the composition a shape corresponding to the shape of the molding space. "Approaching" refers to the process by which the internal space is reduced by moving one or both of the positive and negative molds.

[0257] Dehydration of the structure can be performed by applying a vacuum to the internal space of the mold containing the supplied foam composition.

[0258] The dewatering step is performed before the hot pressing step, whereby a coated final fiber product, that is, a fiber structure in which all layers are bonded to each other, is obtained. In hot pressing, the temperature is usually higher than room temperature, for example at least 50°C, for example at least 100°C.

[0259] The formed fiber structure can be dried by, for example, vacuum, heating, air drying, high-frequency drying, microwave drying, or any combination thereof.

Examples

[0260] (Examples)

[0261] Hereinafter, an embodiment will be described in which, according to some embodiments of the present invention, a fiber structure coated with a dry coating layer is obtained by foam molding using a two-part mold referred to as a pair of molds.

[0262] Any of the features and combinations of features described below can be combined with the embodiments and alternatives previously described in the present application.

[0263] This method is for forming a molded fiber structure. In this method, a layer is formed of a foam. This layer is a part of the final product. The foam, also referred to as a "foam composition", comprises cellulose fibers and / or lignocellulose fibers, water, air, and one or more foaming chemicals. The foam may also comprise fillers and other conventional papermaking chemicals such as, for example, strengthening agents, additives, pigments, colorants, and binders.

[0264] This layer is formed by a pair of molds. The mold may consist of a plurality of partial molds.

[0265] In principle, one mold is a negative mold, and the other mold is a corresponding positive mold. In this way, a three-dimensional shape is obtained during layer formation. Water and air in the foam must be removed. This is mainly done by reducing the distance between the molds and applying pressure. The pressure extrudes water, foaming chemicals and air from the foam supplied between the molds. The porous surface of the mold (the surface of the molded product) provides escape paths for water and air, while fibers form a residual layer.

[0266] The foam can be supplied through one of the molds. The molds are spaced apart from each other and have a closed cavity for the foam. This allows faster supply of the foam and more flexible selection of timing.

[0267] The foam can be supplied through both molds.

[0268] In this example, the pair is formed of an upper mold and a lower mold, the upper mold is movable, while the lower mold is fixed. The foam is supplied through the lower mold.

[0269] The foam can be supplied when the pair are spaced apart from each other, or when the pair are moving relative to each other. This shortens the forming cycle. For example, the foam can be supplied even while the upper mold is ascending. Alternatively, the pair may first be moved away from each other, and only then can the supply of foam be started.

[0270] Passing the foam through the mold provides further advantages. It has become possible to form not only a single layer, but also a plurality of layers by a lamination process. The formed layers can be removed from the inside of the pair after forming. Alternatively, after a layer is formed, the pair can be moved away from each other, more foam can be supplied for an additional layer, and then the pair can be moved closer to each other again. Here again, the foam can already be supplied when the pair are spaced apart from each other.

[0271] In practice, 1 to 10 additional layers, preferably 2 to 4 additional layers, can be formed. After formation and pressing, air and unbound moisture are removed, and a fibrous structure is obtained.

[0272] The next step is hot pressing to remove water bound to the fibers. The layers finally bond together during the hot pressing stage. Multiple hot pressing steps can be applied sequentially.

[0273] Surprisingly, after the first layer, further layers can be formed on either side of the first layer. In other words, the foam may be supplied to either side of the preceding layer. For example, one inner layer may be formed first to function as the main layer, and then another layer may be formed on either side of the inner layer to function as the surface layer. Thus, a total of three layers may be present.

[0274] Multilayer fiber structures can also be fabricated by other methods. The fiber structure can be created by combining multilayer partial fiber structures obtained from two separate pairs of molds. These partial fiber structures formed from the two pairs can be combined and hot-pressed to obtain a single fiber structure. For example, in one pair, one inner layer with one bottom layer can be formed. Simultaneously with the other pair, one inner layer with one top layer can be formed. Combining these layers results in a four-layer fiber structure.

[0275] The rapid formation of multiple layers to constitute a single fibrous structure is a significant advantage. The foam can be replaced before forming one or more additional layers after the first layer. Foams with different properties can be used to form a single fibrous structure. Thus, each layer can be different from the others. The fibrous structure may include, for example, one or two inner layers formed from one type of foam. In that case, there may be at least one outer layer of a different type of foam. Therefore, the cross-sectional shape of the fibrous structure can be altered by the foam.

[0276] Remarkably, the fibrous structure can be formed without additional heating. Because the foam has a low moisture content and contains a lot of air, moisture can be efficiently removed, and the fibrous structure maintains its shape after formation. At the same time, the foam maintains its shape and has low energy consumption.

[0277] The foam temperature is maintained in the range of 15-45°C, preferably in the range of 25-35°C. If necessary, the foam and / or mold can be cooled to keep the temperature stable and sufficiently low.

[0278] At such low temperatures, the fibers retain moisture. During hot pressing, the moisture is released as water and steam, which also provides a smooth surface and contributes to internal bonding, forming a solid, layered fiber structure.

[0279] As soon as the pairs begin to separate, the foam is supplied to the internal space of the mold. When the pairs move closer together again, the supply stops and water is discharged from the pairs. At the same time, air is also removed.

[0280] The removal of water and air by pressing may be facilitated by a vacuum.

[0281] While this method can form a single-layer fiber structure, it is more advantageous when forming multiple layers.

[0282] Foams are made from water, air, fibers, and foaming chemicals. Foams contain small pieces or particles of the fibers in question. Foaming chemicals are also used to promote foam formation and maintain the foam's shape.

[0283] Fibers can vary greatly in their origin and composition. For example, wood fibers or plant fibers (e.g., straw, bagasse, and bamboo fibers) can be used, but artificial cellulose fibers are also possible.

[0284] In a suitable foam, water, fibers and additives are uniformly dispersed in the cell walls of the foam. The foam is a non-agglomerating non-uniform fiber raw material, wherein air in the foam carries the fibers and other raw materials for the forming process. The use of foam also results in very high fiber retention. In practice, more than 99% of the fibers remain in the fiber structure formed from the thick foam as the carrier medium.

[0285] Additives may have different retention properties depending on the purpose.

[0286] By forming the fiber structure with multiple layers, the properties of the structure can be adjusted in various ways. For example, the basic structure and surface properties of the fiber structure may be formed with different foam compositions. In practice, each layer may have its own process parameters and raw materials. For example, the rigid body of the fiber structure may be formed of inexpensive fibers, and the surface layer may be formed of high-quality fibers. Compared with known processes using aqueous fiber slurries, foam provides a much higher fiber density. At the same time, the amount of water in the circulating cell walls is also greatly reduced, which facilitates water removal during forming. Low-water-content foams enable fast process cycles.

[0287] It may be possible to change the proportion or type of foam in different layers of the fiber structure.

[0288] Especially when vacuum is used, the foam can be supplied sufficiently rapidly into the mold cavity.

[0289] In a suitable foam, the cells do not separate and the fibers are uniformly dispersed. During forming, the foam is distributed or supplied into the internal mold space between two molds. The volume of the internal mold space can be adjusted according to the required layer thickness.

[0290] For example, the forming of the next layer can be performed on either side of the preceding layer. Also, the supply of foam may have already started while the mold pair are separated. This is advantageous because during separation, air cannot enter the space ahead of the foam, and the mold space is immediately filled with the foam.

[0291] The foam is supplied through the mold into the internal space of the mold. "Internal space of the mold" refers to the space between a pair of molds.

[0292] Vacuum can also be used. Vacuum is useful for removing water and air. Vacuum can be applied even while the foam is being supplied, or at the latest when the pairs begin to approach each other. During formation, the mold space decreases, but not as much as during the actual pressing steps after formation. Furthermore, it is possible to hold the formed layer under vacuum on the desired mold surface (inner surface) and form an additional layer on a selected side of the previous layer.

[0293] To control the optimal foam structure for uniformly forming the fibrous structure, the formation can be carried out without heating. In practice, the formation is carried out at a substantially constant process temperature, preferably 15-45°C. In addition to a pair of molds, this temperature can be maintained throughout the entire foaming system, ensuring the optimal bubble size or foaming quality for high product quality. In this way, the lifespan of the foam can be extended. Furthermore, it is easier to remove air than with steam, the layers are not damaged, and the process is stable. In practice, the foam contains more than 50% air, preferably 55-75% air.

[0294] The optimal bubble size for the foam during formation is approximately 10 to 500 μm in diameter, preferably 50 to 150 μm or 100 to 200 μm in diameter.

[0295] Remarkably, the foaming process of the present invention simultaneously achieves high viscosity and good formation compared to known aqueous slurry formation processes. These water-based processes require longer heating and dewatering times because they have much lower viscosity and insufficient formation due to aggregation.

[0296] The laminated fiber structure is formed as layers on top of each other. In the dewatering step, water is removed from the formed structure through the mold. The layered structure is joined by hot pressing at the latest.

[0297] The laminated fiber structure can be formed in any order as needed. In other words, formation may begin from any of the inner layers or from any of the outer layers.

[0298] The bonding between layers can be initiated by dehydration through the layer interfaces.

[0299] The bonding of the layers is continued in the subsequent hot-pressing step, or at the latest, occurs in the hot-pressing step, and the bonds between the layers are also strengthened by the heat and steam generated within the fiber structure, as well as the steam passing through the layers.

[0300] Lamination can be performed using the same fiber, but different additives may be used for different layers.

[0301] Hot pressing may include several separate hot pressing stages. Hot air, radiant heating, or impulse drying, preferably impulse drying, may be applied to hot press and / or dry the fiber structure.

[0302] After the hot pressing step, any additional drying steps at high temperature may follow.

[0303] This method involves generating a foam from fibers, water, air, and foaming chemicals. As mentioned earlier, the properties of the foam can vary. Furthermore, this method involves using a pair of molds whose distance from each other varies. In other words, the distance between the molds can vary. In practice, after supplying the foam, the molds are pressed together to remove water and air, thereby forming a fibrous structure.

[0304] Furthermore, this method further includes supplying foam between molds to form layers. A single layer may constitute a fibrous structure, but advantageously, the fibrous structure may include multiple layers. The foam can be supplied even when the molds are separated from each other, and also when the pair of molds are moved relative to each other. This shortens the process cycle and increases the options for coordinating the process and the fibrous structure.

[0305] This method may involve creating a closed mold space and supplying a large amount of foam into the closed cavity-like mold space. The molded fiber structure is removed from the pair and transferred to a hot press.

[0306] Advantageously, this pair includes an upper mold and a lower mold. Either the lower mold is fixed while the upper mold is movable, or the upper mold is fixed while the upper mold is movable, or both molds are movable.

[0307] In a closed mold space, the molds can separate from each other during formation. After separation, the pairs provide space for further foam to enter.

[0308] In practice, the distance between molds is 10 to 100 mm, preferably 20 to 80 mm. In one embodiment, the distance between molds is at least 5 mm. Generally, the thicker the layer, the longer the distance. The foam flow rate is kept at a moderate level. The actual flow rate is 1 to 3 meters per second.

[0309] As mentioned above, several identical fiber structures can be obtained in parallel by a forming method in which each pair of molds comprises several identical partial molds or sub-molds.

[0310] Each section or sub-mold is evenly filled with foam. Therefore, the molded fiber structure is uniform, and the process is rapid.

[0311] After filling the mold space with foam, water and air are removed by pressing. Water and air can pass through the mold surface while fibers accumulate on the mold surface. Water removal can be facilitated by vacuum. Water removal can also be facilitated by excessive pressure applied by the opposing mold.

[0312] The embodiments of the invention disclosed herein are not limited to the specific structures, process steps, or materials disclosed herein, but should be understood to extend to their equivalents as recognized by those skilled in the art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit them.

[0313] Throughout this specification, any reference to “one embodiment” or “a particular embodiment” means that certain features, structures, or characteristics described in relation to that embodiment are included in at least one embodiment of the present invention. Therefore, the phrases “in one embodiment” or “a particular embodiment” appearing in various places throughout this specification do not necessarily all refer to the same embodiment.

[0314] Where used herein, multiple items, structural elements, components, and / or materials may be presented in common lists for convenience. However, these lists are to be interpreted as if each element of the list were individually identified as a distinct and unique element. Therefore, individual elements of such lists should not be interpreted, without the opposite indication, as being substantially equivalent to other elements of the same list based solely on their representation within a common group. Furthermore, various embodiments and examples of the invention may be referenced herein along with alternatives for their various components. It should be understood that such embodiments, examples, and alternatives should not be interpreted as substantially equivalents of each other, but should be considered as distinct and autonomous representations of the invention.

[0315] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. The following description provides many specific details, such as examples of length, width, and shape, to provide a complete understanding of embodiments of the invention. However, those skilled in the art will recognize that the invention can be carried out without one or more specific details, or using other methods, components, materials, etc. In some cases, known structures, materials, or operations are not illustrated or described in detail to avoid obscuring aspects of the invention.

[0316] While the aforementioned examples illustrate the principles of the present invention in one or more specific applications, it will be apparent to those skilled in the art that numerous modifications can be made in terms of form, usage, and implementation details without affecting the inventive step and without departing from the principles and concepts of the present invention. Therefore, the present invention is not intended to be limited except as provided in the claims below.

[0317] In this document, the verbs “to include” and “to provide” are used as open limitations that do not exclude or require the existence of features not mentioned. Features described in dependent claims may be freely combined with each other unless otherwise explicitly stated. Furthermore, it should be understood that the use of “a” or “an,” i.e., the singular form, throughout this document does not exclude the plural form. [Industrial applicability]

[0318] The present invention is industrially applicable, at least in the manufacture of powder-coated molded fiber products. [Explanation of Symbols]

[0319] 1. First fiber layer 2. Second fiber layer 3. Inner fiber layer 4. Middle Class 5 Coating

Claims

1. It is a product, A fibrous structure comprising cellulose fibers and / or lignocellulose fiber material, obtained by a molding process, A coating on at least one surface of the aforementioned fiber structure and Equipped with, The aforementioned coating is obtained by a powder coating process, The aforementioned fiber structure is a multilayer fiber structure comprising at least two fiber layers, Each fiber layer of the aforementioned fiber structure is obtained by foaming and forming the respective fiber composition in a mold. An anionic surfactant is used as the foaming chemical in the foam formation process. The density of the coated fiber structure is calculated as dry solids weight / volume and is between 300 and 1000 kg / m³. ３ It is within the range, The surface smoothness of the coated fiber structure is measured by the ISO 8791-2 benthocene method and is in the range of 50 to 3000 ml / min for the product.

2. The product according to claim 1, wherein the coating forms the uppermost or lowermost layer of the product.

3. The product according to claim 1 or 2, comprising at least two coating layers located on different surfaces of the fiber structure.

4. The product according to claim 1 or 2, wherein the coating is a non-fiber coating and comprises or consists of a thermoplastic polymer material or a thermosetting polymer material.

5. The product according to claim 1 or 2, wherein the coating comprises at least 50 wt% of a thermoplastic polymer material or a thermosetting polymer material.

6. The dry weight of the aforementioned product is 5 to 900 g / m². ２ The product according to claim 1 or 2, which is within the range of the product.

7. The dry weight of the coating is in the range of 2 to 80 g / m². The product according to claim 1 or 2, wherein the thickness of the coating is at least 1 μm.

8. The product according to claim 1 or 2, wherein the fiber structure is a multilayer fiber structure comprising at least a first fiber layer and a second fiber layer, each comprising a cellulose and / or lignocellulose fiber material.

9. The product according to claim 1 or 2, further comprising one or more inner fiber layers between the first fiber layer and the second fiber layer, each comprising a cellulose fiber material and / or a lignocellulose fiber material.

10. Use of the product according to claim 1 or 2 as packaging or container for food, or as packaging for pharmaceuticals or cosmetics, or as part thereof, or for the preservation, handling, preparation or cooking of food.

11. A step of preparing at least one fiber composition comprising cellulose fibers and / or lignocellulose fibers and water, The steps include forming a fiber structure from the at least one fiber composition in a mold, The steps include: coating at least a portion of the surface of the molded fiber structure by a powder coating method; Includes, The above-mentioned at least one fiber composition further comprises a foaming chemical which is an anionic surfactant, The aforementioned fiber structure is a multilayer fiber structure comprising at least two fiber layers, Each fiber layer of the aforementioned fiber structure is obtained by foaming and forming the respective fiber composition in a mold. The density of the coated fiber structure is calculated as dry solids weight / volume and ranges from 300 to 1000 kg / m³. ３ It is within the range, The surface smoothness of the coated fiber structure is measured by the ISO 8791-2 bentosene method and is in the range of 50 to 3000 ml / min, according to the method.

12. The method according to claim 11, wherein the forming step comprises forming a three-dimensional fiber structure from the at least one fiber composition by using a three-dimensional mold.

13. The method according to claim 11 or 12, wherein the powder coating process comprises electrostatically applying a dry powder to the surface of the fibrous structure and curing or melting the applied powder to form a film.

14. The method according to claim 11 or 12, wherein the coated fiber structure has a dry material content of at least 90%.

15. After the forming step and before applying the coating, The steps include dehydrating the aforementioned structure, The method further includes the step of hot-pressing the dehydrated structure to obtain a molded three-dimensional fiber structure, The method according to claim 11 or 12, wherein the hot press produces a surface suitable for direct powder coating.

16. The dry material content of the coated fiber structure is at least 60%. The method according to claim 11 or 12, wherein, after coating, the coated structure is hot-pressed.

17. The density of the coated fiber structure is at least 700 kg / m³ ３ The method according to claim 11 or 12.

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