Patent Application
20240367426
The invention generally concerns multilayered articles and uses thereof.
Cellulose Nanocrystals (CNC) are one of the known forms of cellulose, the main component of cell walls of trees and plants. CNC may be present as liquid crystal solution in water and is known to self-assemble to macro scale ordered films having thicknesses at the nanoscale.
The nano-sized crystals possess interesting size-dependent structural and optical properties. The ability to play with the processing variables provides the ability to control the structure, composition, size, and level of dispersion of such nano crystals.
The inventors of the technology disclosed herein have developed highly stable and versatile multilayered structures or articles, based on cellulose nanomaterials, such as cellulose nanocrystals (CNC), that can be tailored and processed for a variety of applications and which are superior materials to aluminum sheets used, e.g., in the food packaging industry, as well as to other polymer-based structures and articles, and which exhibit superior barrier properties to gases, organic solvents, oils and other agents.
As demonstrated herein, articles of the present invention, being multilayered structures that may be used in a variety of products and applications, have demonstrated superiority also with respect to existing and known products constructed of multilayers of cellulose nanomaterials and polymers such as polyvinyl alcohol (PVOH).
Superiority of multilayered structures of the invention is, inter alia, based on the presence of a layer of a blend of CNC and PVOH (CNC-PVOH blend). The superiority is reflected in:
These properties support highly unique and useful articles that are in no way comparable to similar articles of the art. For example, a CNC-PVOH blend film shows better mechanical and barrier properties, compared to neat PVOH film and compared to a CNC film. In a multilayer structure of the invention, the advantage of CNC-PVOH layer, as compared to neat PVOH layer, is further increased, by the formation of better interactions between the CNC-PVOH layer and its adjacent layers, which enhance the adhesion between layers, and improve barrier properties and mechanical properties, as compared to multilayered-structures comprising neat PVOH. Where PVOH shows good performance as a barrier, CNC-PVOH exceeds its performance and exhibits excellent to superior properties, and the inclusion in a multilayer structure enhances the performance even more.
In contrast to multilayered structures of the art, such as those disclosed for example in US20050042443, at least one layer of PVOH coating, and a total coating weight of at least 7 gr/m2 are needed in order to provide a TAPPI T 559 standard rating of 12, when coated on paper substrates. A CNC-PVOH coating resulted in a TAPPI T 559 standard rating of 12 when a coating weight of only 2.5 gr/m2 was used, thus proving that the performance of such multilayered structures of the invention is beneficial as compared to e.g., PVOH coatings alone.
Oxygen barrier properties of multilayered structures comprising CNC-PVOH blends over PVOH-based layers was also demonstrated. On Kraft paper and paperboards, oxygen transmission rates of structures consisting PVOH were measured to be 1.5-2 times higher (lower barrier) than for structures with CNC-PVOH, for the same weight, when not consisting plastic layers. Structures with plastic layers and PVOH barrier layer showed 2 to 20 times higher OTR values (lower barrier). Kraft paper coated with a 5 g/m2 PVOH layer resulted in an OTR (at 80% RH) of 20-30 cc/m2-day compared to an OTR of 8-15 cc/m2-day for a 5 g/m2 CNC-PVOH layer under the same conditions. Structures of PP/paperboard/PVOH (5 g/m2)/PP resulted in an OTR (at 80% RH) of 10-20 cc/m2-day as compared to an OTR of 0.5-5 cc/m2-day for the same structures with a 5 g/m2 CNC-PVOH layer under the same conditions.
As a person versed in the art would realize, OTR values are typically obtained and reported for multilayered structures tested at 0% relative humidity (RH). In practical terms, this value has no meaning when producing a structure for packaging purposes, since the terms of use of such structures always involve RH levels that are always higher than 0%. Moreover, the RH levels in which barrier products are used in the industry is 80% RH. Many barrier layers, including PVOH or PVOH-based barrier layers, show OTR stability when measured at ˜50% RH, but then exponentially increase in OTR values, as the RH levels increase. Thus, a prior art such as U.S. Pat. No. 9,227,381, in which a PVOH-based layer leads to OTR values of 4-12 cc/m2-day at 0% RH, does not provide any indication nor allow predication of barrier capabilities at 80% RH. In contrast, OTR values measured for structures with a CNC-PVOH layer are less than 1 cc/m2-day under the same conditions and are thus comparable to structures containing metalized layers, described in the art.
In U.S. Pat. No. 5,547,764, PVOH and mixtures of PVOH grades were coated on polypropylene (PP) and tested for OTR at 0% and 75% RH. The best OTR value disclosed was >20.15 cc/m2-day at 75% RH, which is higher than the OTR value obtained for a PP layer coated with a CNC-PVOH layer of the invention, which in comparison demonstrated, at 80% RH, a value of <15 cc/m2-day.
Adhesion advantages of a CNC-PVOH barrier layer, used in accordance with the invention, over a PVOH barrier layer, have also been demonstrated herein. A multilayer structure in which the barrier layer is in contact, on one of its faces or on both faces, with a plastic layer, must involve a strong adhesion between the barrier and plastic layers. Low adhesion is expected to lead to detachment and separation of the layers, during production of an end product, such as a package, or when the product is used. As demonstrated, a multilayer structure in which PVOH was used instead of a layer of CNC-PVOH, in contact with a plastic layer, resulted in 3-10 times weaker adhesion interaction between the barrier layer and the plastic layer as compared to the adhesion of CNC-PVOH layer to the same plastic layer (0.5 N/15 mm for PVOH compared to 1.5-5 N/15 mm for CNC-PVOH).
Articles of the invention are free of metallic layers and achieve their stability, durability and improved properties even in the absence of such layers. In fact, articles of the invention are free of any metallic nanoparticles and are generally free of any metal-containing layer and are thus suitable for a wider variety of applications, including as packaging materials for food, beverages, consumer goods and pharmaceutical products. These articles may be tailored or pre-structured in accordance with one or more final uses or applications. For example, an article according to the invention may be specifically tailored as a dry food packaging material or as a liquid food packaging material. Additionally, articles of the invention are fully biodegradable or comprise at least one layer that is biodegradable or are generally degradable.
In a first aspect, the invention provides an article in the form of a multilayered structure (which may be in the form of a substantially two-dimensional sheet or a three-dimensional article or product) comprising a plurality of material layers, e.g., three or more material layers, at least one of said three or more material layers comprising a cellulose nanomaterial selected from cellulose nanocrystals (CNC), microfibrillated cellulose (MFC), a combination of CNC and nanofibrilar cellulose (NFC), a combination of CNC and MFC, or a blend of CNC with at least one additive, e.g., a polymer that is water soluble or water dispersible (such as hydroxyl or carboxyl-rich polymers).
In some embodiments, the cellulose nanomaterial is CNC or is not microfibrillated cellulose (MFC).
In some embodiments, each of the three or more (at least three) material layers is biodegradable or generally degradable and is free of metallic materials or components.
In some embodiments, the multilayered article comprises a substrate, a cellulose nanomaterial, e.g., CNC-based layer (such as a blend of CNC and PCOH), and a cover layer, such that the cellulose nanomaterial layer forms an interface between the substrate and the cover layer. Where the multilayered structure comprises more than three layers; namely a substrate, a cellulose nanomaterial, a cover layer and another layer interposed between the substrate and the cover layers, the cellulose nanomaterial layer may be positioned anywhere relative to the another layer (e.g., the cellulose nanomaterial layer need not be positioned equidistant from the substrate and the cover layers).
In some embodiments, the multilayered article consists a substrate, a CNC-based layer and a cover layer, such that the CNC-based layer forms an interface between the substrate and the cover layer.
In some embodiments, the substrate and the cover layer are the same. In some embodiments, the substrate and the cover layer are different.
As used herein, a “material layer” is any such layer that comprises or consists the indicated material, exhibiting a uniform or homogenous distribution of the material along the layer. The material layer may be composed of a single layer or composed of a plurality of layers, wherein each of the plurality of layers comprises the same material. Where the two layers are distinct in their composition, they may be regarded as two different material layers. For example, a material layer comprising at least one cellulose nanomaterial, may be structured of several layers of the same material, wherein the several layers are used to, e.g., increase the thickness of the layer. Where two different cellulose materials are used as a blend, as defined, such a blend may be used to form a material layer. However, as defined herein, wherein the two materials are not in the form of a blend, each would form a different layer of the multilayered structure.
Each material layer has a thickness ranging from 100 nm and 20 μm. In some embodiments, the thickness is between 100 and 900 nm, between 900 nm and 20 μm, between 1,000 nm and 20 μm, between 1 μm and 20 μm or between 1 μm and 10 μm.
Each material layer of the multilayered structure is adhesively connected, associated or attached to one or two adjacent (neighboring) layers. The term “adhesive connection/association/attachment” or any lingual variation thereof, refers to the fact that any two adjacent layers in a multilayer are intimately associated to each other through the use of an adhesive layer or by pre-treating one or both of the to-be-associated layers to permit effective association. Such pretreatment may include thermal treatment, a treatment with plasma, corona, flame, primer application or any other known pretreatment method. Where an adhesive layer is used, it may be an interface layer between any two material layers having a thickness of between 100 nm and 3 μm or may be considered an independent layer of the multilayer, as may be the case. Suitable adhesives or primer materials are disclosed hereinbelow.
In some embodiments, the association or adhesion between the two layers does not require the use of an adhesive or a primer formulation, nor any pretreatment of any of the layers to be associated. In some cases, a layer e.g., a layer of CNC-PVOH blend, as described herein, is formed onto the other, e.g., a paper-based substrate, without needing to use an adhesive, a primer formulation, or any pretreatment.
In another aspect, the invention provides an article in the form of a multilayered structure comprising a plurality of material layers (three or more layers), at least one of said material layers is a substrate layer and at least one another of said material layers is a layer of CNC-PVOH blend.
In some embodiments, the multilayered structure is characterized by one of more of the following:
In another aspect, the invention provides an article in the form of a multilayered structure comprising a plurality of material layers (three or more layers), at least one of said material layers is a substrate layer and at least one another of said material layers is a layer of CNC-PVOH blend, wherein the article has a grease barrier value of 12, as determined using TAPPI T 559 standard (approved by the Physical Properties Committee of the Process and Product Quality Division).
In another aspect, the invention provides an article in the form of a multilayered structure comprising a plurality of material layers (three or more layers), at least one of said material layers is a substrate layer and at least one another of said material layers is a layer of CNC-PVOH blend, wherein the article has an oxygen transmittance rate (OTR) of between 0.01 and 15, or between 0.01 and 1, or between 0.01 and 5, or between 1 and 10, or between 1 and 5 or generally of values below 1, when measured at 80% relative humidity (RH), at 23° C.
In another aspect, the invention provides an article in the form of a multilayered structure comprising a plurality of material layers (three or more layers), at least one of said material layers is a substrate layer and at least one another of said material layers is a layer of CNC-PVOH blend, wherein the article has a water vapor transmittance rate (WVTR) of between 0.01 and 20, or between 0.01 and 1, or between 0.01 and 5, or between 1 and 10, or between 1 and 5, or between 5 and 10, or generally of values below 1, when measured at 90% RH, at 38° C.
As used herein, the term “blend” refers to a mixture of any two or more components, as indicated, that forms a layer of the invention. A layer of “CNC-PVOH blend”, for example, refers to a material layer that comprises a mixture of CNC and PVOH, at any material ratio. Typically, such a material layer consists the blended materials; namely the blend from which the layer is formed consists the two (or more) materials only. In some embodiments, the blend may comprise one or more additives or other materials. Thus, in some embodiments, a CNC-PVOH material layer consists CNC and PVOH. In some embodiments, a CNC-PVOH layer is provided that comprises a blend of CNC and PVOH.
A blend of CNC and PVOH is a mixture of the two components at a ratio between 0.001:1 to 1:0.001 (CNC to PVOH). In some embodiments, the ratio is 0.001:1, 0.01:1, 0.1:1, 1:1, 1:0.1, 1:0.01, 1:0.001 w/w, CNC:PVOH.
In some embodiments, the ratio is 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20 w/w, CNC:PVOH.
In some embodiments, in a blend of CNC and PVOH, the amount of CNC is between 1 and 99% of the CNC+PVOH weight. In some embodiments, the amount of CNC in the combination CNC+PVOH is between 1 and 99%, 1 and 95%, 1 and 90%, 1 and 85%, 1 and 80%, 1 and 75%, 1 and 70%, 1 and 65%, 1 and 60%, 1 and 55%, 1 and 50%, 1 and 45%, 1 and 40%, 1 and 35%, 1 and 30%, 1 and 25%, 1 and 20%, 1 and 15%, 1 and 10%, 1 and 5%, 10 and 99%, 15 and 99%, 20 and 99%, 25 and 99%, 30 and 99%, 35 and 99%, 40 and 99%, 45 and 99%, 50 and 99%, 55 and 99%, 60 and 99%, 65 and 99%, 70 and 99%, 75 and 99%, 80 and 99%, 85 and 99%, 90 and 99%, 10 and 50%, 15 and 50%, 20 and 50%, 25 and 50%, 30 and 50%, 35 and 50%, or between 40 and 50%, w/w.
In some embodiments, each of the plurality of material layers is biodegradable and is free of metallic materials or components. In some embodiments, the substrate layer is biodegradable and in other embodiments, the CNC-PVOH layer is biodegradable.
In some embodiments, the article has a layered structure of the form ABC, wherein each of A, B and C is one or more material layers, as depicted in
In some embodiments, each of material layers A, B and C is free of metallic materials or components.
In some embodiments, layer A and/or C may be selected, independently, from a polymeric material, a paper or paper-based material, a polymer coated paper-based material, e.g., a paperboard, a nanocellulose film, nanocellulose/polymer film, a fabric material, a porous material and a membrane material.
The “polymeric material”, when used as an independent layer or as a coating layer of a paper-based material or a nanocellulose material or as an additive to any of the materials constructing any of the layers, may be a material belonging to any known polymeric material or resin, such as thermoplastic polymers and thermoset polymers. The polymer may be selected amongst such polymers as polyethylene, polypropylene, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate. In some embodiments, the polymeric material is polyester (which may be selected amongst thermoset and thermoplastics).
In some embodiments, the polymer is selected from polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate, or any blend of two or more thereof.
As used herein, “paper or paper-based material” is a material as known in the art. The paper or paper-based material may be used as such or may be used coated with a polymer on one or both its faces. In some embodiments, this paper-coated material is a paperboard. In some embodiments, the paper is Kraft paper. As known in the art, Kraft paper is a paper or paperboard (cardboard) produced from chemical pulp produced in the Kraft process, as known in the art. The paper is a porous paper with high elasticity and high tear resistance, designed for packaging products with high demands for strength and durability. Thus, the paper may additionally be selected from paper-based packaging materials.
In some embodiments, the paper is selected from bank paper, banana paper, bond paper, book paper, coated paper products, construction paper, sugar paper, cotton paper, fish paper, inkjet paper, Kraft paper, Sack Kraft paper, laid paper, leather paper, mummy paper, oak tag paper, sandpaper, Tyvek paper, wallpaper, Washi paper, waterproof paper, wax paper, wove paper, Xuan paper and others.
As known in the art, commercial papers or paper-based products of any kind described above, may contain additives such as clays, calcium carbonate, latex, etc., which are added to the paper in its production process.
The “fabric material” is any such material known in the art that is typically a flexible material constructed of a network of natural or artificial fiber materials. The fabric may be any textile, natural fabric, synthetic fabric, knit, woven material, nonwoven material or mesh of a material selected from cellulose, viscose, glass fibers, carbon fibers and synthetic fibers. In some embodiments, the fabric may be in the form of a porous material or a membrane, selected as indicated.
The “porous material” or “membrane material” is generally a material containing pores that can hold or contain a solid, liquid or gaseous materials. IN some embodiments, the pores are voids, namely empty of any such material. In some embodiments, the porous material acts as a membrane, namely as a selective barrier with a degree of selectivity being dependent on the membrane pore size. In some embodiments, the membrane may be fabric based or paper based.
Each of layers A and C, independently one of the other, may additionally or alternatively, be coated or made of a polymeric material that is known as a varnish material. As known in the art, such varnishes are hydrophobic materials that by themselves can act as water-resistant layers, water vapor barriers or supply mechanical protection to any layer they are associated with, e.g., layer B, or any of layers A and C as defined herein. The varnish layers, either directly on layer B or on either or both layers A or C may also be provided to gain the ability to print on. The varnish material or composition may be obtained as commercially available or may be tailored for the particular purpose. The varnish material may be selected amongst such compositions that contain a polymer selected from polyurethane, acrylic, epoxy, polyester; resins such as phenolic resin, alkyd resin, polyurethane resin; latexes such as styrene, styrene-butadiene, natural latex; and oils such as linseed oil, walnut oil, tung oil and soybean oil.
In some embodiments, neither substrate A nor cover layer C is a nanocellulose film nor comprises such a material.
It should be noted that the terms “substrate” and “cover layer” should not be taken to suggest or hint to any directionality to articles of the invention. In other words, the term “substrate” need not be the bottom-most layer or the layer from which manufacture of the article commences. Similarly, the term “cover layer” should not be contemplated as the top-most layer nor the layer that caps, envelopes or covers the remaining layers or features of the multilayered structure.
As noted herein, layer B comprises or consists a cellulose nanomaterial, such as a blend of CNC and NFC. In some embodiments, layer B is free of NFC.
Cellulose nanocrystals (CNC) or nanocrystalline cellulose (NCC) are fibers produced from cellulose, wherein the CNC are typically high-purity single crystals. They constitute a generic class of materials having mechanical strengths equivalent to the binding forces of adjacent atoms. The resultant highly ordered structure produces not only unusually high strengths but also significant changes in thermal, electrical, optical, magnetic, ferromagnetic, dielectric, conductive, and even superconductive properties. The tensile strength properties of CNC are far above those of the current high volume content reinforcements and allow the processing of the highest attainable composite strengths.
CNC may be produced from cellulose or any cellulose containing material or from fibrillated cellulose by means known in the art, for example in WO 2012/014213, WO 2015/114630, and in US applications derived therefrom, each being herein incorporated by reference.
As known in the art, cellulose nanofibrils (CNF or NFC) are cellulosic materials composed of at least one primary fibril, containing crystalline and amorphous regions, with aspect ratios usually greater than 50. Their length is 0.1-5 μm and their diameter is 5-60 nm. Similarly, cellulose microfibrils (CMF or MFC) are cellulosic materials containing crystalline and amorphous regions, with aspect ratios usually greater than 50. Their length is few micrometers and their diameter is larger than 100 nm. CMF can contain some fraction of CNF.
In some embodiments, the cellulose nanomaterial is characterized by having at least 50 percent crystallinity. In some embodiments, the cellulose nanomaterial is monocrystalline. In some embodiments, the cellulose nanomaterial is high purity monocrystalline material.
In some embodiments, the nanocrystals of the nanomaterial have a length of at least about 50 nm. In other embodiments, they are at least about 100 nm in length or are at most 1,000 nm in length. In other embodiments, the nanocrystals are between about 100 nm and 1,000 nm in length, 100 nm and 900 nm in length, 100 nm and 600 nm in length, or between 100 nm and 500 nm in length.
In some embodiments, the nanocrystals are between about 10 nm and 100 nm in length, 100 nm and 1,000 nm, 100 nm and 900 nm, 100 nm and 800 nm, 100 nm and 600 nm, 100 nm and 500 nm, 100 nm and 400 nm, 100 nm and 300 nm, or between about 100 nm and 200 nm in length.
The nanocrystals may be selected to have an averaged aspect ratio (length-to-diameter ratio) of 10 or more. In some embodiments, the averaged aspect ratio is between 10 and 100, or between 20 and 100, or between 30 and 100, or between 40 and 100, or between 50 and 100, or between 60 and 100, or between 70 and 100, or between 80 and 100, or between 90 and 100, or between 61 and 100, or between 62 and 100, or between 63 and 100, or between 64 and 100, or between 65 and 100, or between 66 and 100, or between 67 and 100, or between 68 and 100, or between 69 and 100.
In some embodiments, the averaged aspect ratio is between 67 and 100.
In some embodiments, the cellulose nanomaterial is CNC. In some embodiments, the nanomaterial is not NFC.
Depending on the process utilized for the production of the CNC, the material may be in a variety of purities. In some cases, the cellulose nanomaterial may comprise salts and/or carbohydrates such as hemicellulose, xyloglucane, cellulose derivatives and others. Thus, the CNC used in accordance with the invention may comprise between 0.01% and 0.5% of impurities, e.g., carbohydrates and salts.
Layer B endows the multilayered structure with one or more properties that may be enhanced, reduced or otherwise modified by selecting an appropriate substrate or cover layer or by increasing or decreasing or selecting a certain number of layers. In some embodiments, the material composition of layer B is selected to exhibit gas barrier properties, oil barrier properties and water vapor barrier properties. The gas barrier properties include preventing, arresting, or minimizing permeation or transport of gases through the multilayered structure, the gas being selected from oxygen, carbon dioxide, aroma, SOx, NOx, methane, fluorinated gases and others. The oil barrier properties include preventing, arresting, or minimizing permeation or transport of oils such as vegetable oil, mineral oil and grease.
Layer B may also be selected to have a composition or a thickness that endows the multilayered structure with mechanical support. It may be a transparent layer or an opaque or non-transparent, and in some cases may be tailored to block certain wavelengths.
In some embodiments, layer B comprises a blend of CNC with at least one other nanocellulose material such as NFC, or with at least one additive, or with at least one additional material.
In some embodiments, layer B consists CNC, or a combination of CNC and NFC.
A blend of CNC and NFC is a mixture of the two components at a ratio between 0.001:1 to 1:0.001 (CNC to NFC). In some embodiments, the ratio is 0.001:1, 0.01:1, 0.1:1, 1:1, 1:0.1, 1:0.01, 1:0.001 w/w, CNC: NFC.
In some embodiments, layer B comprises CNC in combination with (as a blend) at least one polymer selected from polyvinyl alcohol (PVOH), polyvinyl acetate (PVAc), ethylene vinyl alcohol (EVOH), polyvinyl pyrrolidone (PVP), starch, chitosan, poly acrylic acid (PAA), polyethyleneimine (PEI), carbohydrates, ethylene vinyl acetate (EVA), elastomers, isocyanates and polyurethanes.
In some embodiments, layer B is a CNC layer that may consist CNC or may comprise a blend (a mixture, not separate layers) of CNC and at least one additive selected to endow the CNC material or layer with one or more properties selected from gas barrier, oil barrier, water-vapor barrier, better mechanical properties, thermal properties, adhesive properties and others.
In some embodiments, B is a layer of a blend of CNC and PVOH.
The at least one additive may be a polymer, as defined herein, or any other additive such as a plasticizer, e.g., glycerol or sorbitol; a surfactant, e.g. polysorbate; a particulate material, e.g., Mg particles or nanoparticles (excluding nanoparticles of others elements); a pigment; a carbohydrate, e.g. starch or chitosan; a salt, e.g. calcium carbonate; a conductive material, e.g. graphene; an oxygen scavenger, e.g. iron-salts; lignin; natural extracts, e.g. rosemary oil and others.
In some embodiments, the additive or any other material used in combination with the CNC and/or NFC is not bi oriented poly propylene (BOPP).
In some embodiments, the additive is a polymeric material.
In some embodiments, the additive is not a polymeric material.
Where the additive is not a polymer, the additive may be present in amounts as indicated herein or in amounts ranging from 1% and 30% of the total weight of the formula (w/w). In some embodiments, the additive amount may be between 1 and 10%, 1 and 20%, 1 and 5%, 5 and 10%, 10 and 15% or 10 and 20%.
The cellulose nanomaterial, e.g., CNC, layer may be comprised of the nanomaterial, such as CNC and at least one additional agent or material, e.g., a polymeric material, wherein the amount of the additive, e.g., polymeric material, ranges between 0.1-99 wt % of the nanomaterial layer (relative to the total weight amount of the materials making up the layer). In some embodiments, the amount of the polymeric material is between 0.1 and 95%, 0.1 and 90%, 0.1 and 85%, 0.1 and 80%, 0.1 and 75%, 0.1 and 70%, 0.1 and 65%, 0.1 and 60%, 0.1 and 55%, 0.1 and 50%, 0.1 and 45%, 0.1 and 40%, 0.1 and 35%, 0.1 and 30%, 0.1 and 25%, 0.1 and 20%, 0.1 and 15%, 0.1 and 10%, 0.1 and 9%, 0.1 and 8%, 0.1 and 7%, 0.1 and 6%, 0.1 and 5%, 0.1 and 4%, 0.1 and 3%, 0.1 and 2%, 0.1 and 1%, 1 and 90%, 5 and 90%, 10 and 90%, 15 and 90%, 20 and 90%, 25 and 90%, 30 and 90%, 35 and 90%, 40 and 90%, 45 and 90%, 50 and 90%, 55 and 90%, 60 and 90%, 65 and 90%, 70 and 90%, 75 and 90%, 80 and 90%, 85 and 90%, 1 and 85%, 5 and 80%, 10 and 80%, 15 and 75%, 20 and 70%, 25 and 65%, 30 and 60%, 35 and 55% or 40 and 50%.
In some embodiments, the at least one additional material is a polymer such as PVOH, present in an amount between 50 and 70% or between 60 and 70% or between 70 and 95% or between 70 and 80% of a composition consisting the additive and CNC (in other words—an amount between 70% and 90% polymer means 70-90% polymer and 30-10% CNC).
In some embodiments, the ratio of at least one additional material to CNC is 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1 or 2:1.
In some embodiments, layer B comprises CNC and PVOH (CNC-PVOH). The layer has a thickness of between 100 nm and 20 μm. In some embodiments, the thickness is between 100 and 900 nm, between 900 nm and 20 μm, between 1,000 nm and 20 μm, between 1 μm and 20 μm or between 1 μm and 10 μm.
In some embodiments, the thickness is between 1 μm and 20 μm, between 1 μm and 20 μm, between 1 μm and 15 μm, between 1 μm and 10 μm or between 1 μm and 5 μm.
Each of layers A and C endows the multilayered structure with mechanical and barrier capabilities that may be tailored to meet one or more end applications. Both the substrate and the cover layer may be printed on, laminated or otherwise associated with one or more layers, sheets, films or coats. A multilayered structure having the general form ABC, may be folded or arranged into a pocket or a container or an enclosure such that either A or C can be the external surface of the pocket or container or enclosure, or the internal surface thereof. Depending on the final product, the material or composition of each of layers A and C may be selected.
In some embodiments, each of layers A and C is selected, independently of each other, amongst polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate.
In some embodiments, one of layers A and C is a polymer coated paperboard, wherein the polymer is selected from polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate.
In some embodiments, at least one of layers A and C, independently of the other, is or comprises a fabric. The fabric may be any textile, natural fabric, synthetic fabric, knit, woven material, nonwoven material or mesh of a material selected from cellulose, viscose, glass fibers, carbon fibers and synthetic fibers. Similarly, the fabric may be in the form of a membrane, selected as indicated.
Layers A and B and/or layers B and C may be associated with each other directly or may be separated by an interface material(s) as depicted for the purpose of exemplification in
Additionally or alternatively, the layers may be adhesively associated to each other, as defined, via a primer material or an adhesive material, shown in
As may be understood the adhesive or primer may also be used to associate any two or more layers of the multilayer to each other. The so associated layers need not be the substrate or the cover layer. They may be any layer of the multilayer with any other layer of the multilayer.
In some embodiments, the multilayered structure comprises 3 layers: a substrate layer (A), a CNC layer (B) and a cover layer (C), each as defined herein, as exemplified in
In such multilayer designations, both C1 and C2 are selected as defined herein for C, but are nevertheless different from each other.
In some embodiments, each of layers A and C is repeated twice or more, namely a multilayered structure may be in the form AABCC, or ABCC, or AABC, or AABCBC, or ABCBCC, wherein each of A, B and C are as defined herein, and further wherein each pair of adjacent layers may be associated directly or via a primer or adhesive film or layer. For example, in a structure of the from AABCC, each A may be different from the other and each C may be different from another C. As material layers A and C may be selected amongst the same materials, the multilayered structure may be symmetric around the central layer B or asymmetric.
The multilayered structure of the invention may be in the form of a sheet or a folded or shaped sheet of material, as defined herein. Where presented as a material sheet, it may be of any size and shape, may be printed or colored, may be fully transparent or opaque and may be surface treated. The sheet may be cut, folded, or processed into any one shape, size or object such as a pocket or an enclosure or an envelope or a container that is formed of the sheet, or that comprises at least one element or feature that is made of a multilayered structure of the invention. In some embodiments, the object is for packaging of goods, foods, liquids, pharmaceuticals or any material that requires isolation or protection from the environment, e.g., gases, water vapor, certain light wavelengths, and other damaging agents or effects which the multilayered structure can protect from (by forming an impermeable barrier).
Due to its unique properties, the sheet may be used as a replacement for aluminum sheets in packaging materials. As known in the field, aluminum sheets are widely used in packaging products due to their ability to fully block permeation of gases, water and light, and also due to their contribution to the mechanical stability of the package. There are however certain disadvantages for the use of aluminum foils, mainly having to do with its impact on the environment caused by its inability to undergo degradation, and difficulties associated with the recycling of packages containing aluminum. Light blocking properties of aluminum are also considered a disadvantage when transparent packages are needed. Another disadvantage of aluminum is heat transmittance which is not desired in applications such as vacuum insulated panels, where good gas barrier is needed but without high heat transfer.
The layered structure of the invention is a suitable replacement of aluminum by providing a material having barrier and mechanical properties, with the benefit of being recyclable and degradable, being transparent to light, thermal insulator, and can be provided as much thinner barrier layers, achieving the same desired barrier properties (for example, a 2 μm barrier layer leads to the desired OTR level in a structure that 5 μm of aluminum foil is usually used in).
Thus, in accordance with some aspects, the invention provides an article in the form of a multilayered structure consisting between 3 and 7 material layers, the multilayered structure being of the form ABC, wherein each of A, B and C is a material layer selected as indicated herein. In some embodiments:
In some embodiments, the layer of the cellulose nanomaterial comprising between 0.1 wt % and 3 wt % impurities of the total weight of the layer, wherein the impurities are selected from carbohydrates and salts.
In some embodiments, the article consisting a layer of CNC or a layer of a blend of CNC and at least one additional agent; a substrate; and a cover layer.
In some embodiments, the article consisting a layer of a blend of CNC and PVOH; a substrate and a cover layer.
In some embodiments, each of layer A and layer C is a paper or paper-based material.
In some embodiments, each of layer A and layer C is of a polymeric material, a polymer coated paper-based material, or a nanocellulose/polymer film.
In some embodiments, layer B comprises CNC blended with at least one polymer selected from PVOH, PVAc, EVOH, PVP, starch, chitosan, poly acrylic acid, polyethyleneimine, carbohydrates, EVA, elastomers, isocyanates and polyurethanes.
In some embodiments, the at least one additive is a polymer or an additive selected from a plasticizer; a surfactant; a particulate material; a pigment; a carbohydrate; a salt; a conductive material; and an oxygen scavenger.
In some embodiments, the at least one additive is present in an amount ranging from 1% and 20%.
In some embodiments, layer B is of a thickness of 100 nm-20 μm.
In some embodiments, each of layers A and C is of a material selected, independently of the other, from polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate.
In some embodiments, one or both of layers A and C is a polymer coated paperboard, wherein the polymer is selected from polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate.
In some embodiments, at least one of layers A and C, independently of the other, is or comprises a fabric.
In some embodiments, layers A and B and/or layers B and C are associated with each other directly or separated by an interface material selected from primer material and an adhesive material.
In some embodiments, the article consists 3 layers: a substrate layer, a CNC layer and a cover layer.
In some embodiments, the CNC layer consisting a blend of CNC and PVOH.
In some embodiments, the multilayered structure is of a form selected from AABCC, ABCC, AABC, AABCBC, ABCBCC, wherein each of A, B and C are as defined herein.
In some embodiments, the article is provided when used in packaging of goods, foods, liquids, and pharmaceuticals.
The invention additionally provides an article in the form of a multilayered structure consisting between 3 and 7 material layers, the multilayered structure being of the form ABC, wherein each A, B and C is a material layer, wherein:
Packages with good gas barrier properties are suitable for long-term, aseptic packaging of food-stuff and beverages. Thus, it is very important to achieve very low oxygen-transmission rates (OTR) in developed packaging solutions. Moreover, those low OTR values must be achieved in humid conditions, which better correlate to “real-life” conditions and better predict the performance of the barrier in granting longer shelf life to the packaged food-stuff or beverages. An excellent oxygen barrier will show OTR values below 10 cc/m2-day. Good oxygen barrier will show OTR values of few dozens, and so on. The OTR values, as measured using a coulometric oxygen sensor, are crucial for the determination of the final barrier product performance, and an improvement of few OTR units may attest to a big difference in the ability of the final package to prolong the shelf life of products. For that reason, the better OTR values achieved for structures consisting of a CNC-PVOH barrier layer compared to structures consisting of a PVOH barrier layer, indicate that the final package will be superior when using CNC-PVOH as a barrier layer.
Thus, the invention also provides multilayered structures, as defined, in which layer B comprises or consists a blend of CNC and PVOH at ratios, as indicated herein. The ratio between the CNC and the PVOH in the blend may be selected from 1:1 and 1:40 CNC/PVOH, as detailed herein.
The following non-limiting examples of the invention represent multilayered structures that by themselves or when modified to include one or more additional material layers, provide a beneficial improvement on existing structures known in the art. In some embodiments, multilayered structures of the invention consist or comprise any one or more of the following (in each of the examples, the sign “/” indicates separation between layers):
Following are specific properties:
In comparison to each of the above exemplary multilayers, a Kraft paper without barrier exhibited no oxygen barrier at all, the paper failed the grease test, and demonstrated no water or water-vapor barrier properties.
In some embodiments, layer A is a paperboard and layer B comprises a blend of CNC and PVOH at a ratio as defined, e.g., being between 1:2 and 1:40 CNC/PVOH. Non-limiting examples include:
As indicated, multilayered structures of the invention have exhibited improved oxygen transmission rates, water-vapor transmission rates, grease and oil barrier capabilities as well as water sorptivity properties, just to name a few, as compared to multilayers of the art.
For example, improved oil barrier properties of multilayers comprising a CNC-PVOH blend layer over PVOH based layers or layers of water-vapor polymers, when coated on Kraft paper or a paperboard have been demonstrated:
Thus, a CNC-PVOH layer in a multilayered structure of the invention, demonstrated improved properties acting as a barrier layer, and additionally demonstrated synergistic effect with polymeric water-vapor barrier layers, especially those based on acrylic emulsions or styrene-butadiene emulsions. The combination of the two layers led to the best oil/grease barrier capabilities, including resistance to creasing and folding, which is essential in the production of liquid and food packaging.
The invention thus provides:
An article in the form of a multilayered structure comprising three or more material layers, at least one of said three or more material layers is a substrate layer and at least one another of said three of more material layers is a layer of a blend of cellulose nanocrystals (CNC) and polyvinyl alcohol (PVOH).
The following embodiments relate to any of the aspects disclosed herein as well as to any embodiments disclosed, in combination.
In some embodiments, the article is characterized by one of more of the following:
In some embodiments, the OTR is between 0.01 and 1 cc/m2-day, when measured at 80% relative humidity (RH), at 23° C.
In some embodiments, the OTR is between 0.01 and 5 cc/m2-day, when measured at 80% relative humidity (RH), at 23° C.
In some embodiments, the OTR is between 1 and 10 cc/m2-day, when measured at 80% relative humidity (RH), at 23° C.
In some embodiments, the OTR is between 1 and 5 cc/m2-day, when measured at 80% relative humidity (RH), at 23° C.
In some embodiments, the OTR is below 1 cc/m2-day, when measured at 80% relative humidity (RH), at 23° C.
In some embodiments, the WVTR is between 0.01 and 1 gr/m2-day, when measured at 90% RH, at 38° C.
In some embodiments, the WVTR is between 0.01 and 5 gr/m2-day, when measured at 90% RH, at 38° C.
In some embodiments, the WVTR is between 1 and 10 gr/m2-day, when measured at 90% RH, at 38° C.
In some embodiments, the WVTR is between 1 and 5 gr/m2-day, when measured at 90% RH, at 38° C.
In some embodiments, the WVTR is between 5 and 10 gr/m2-day, when measured at 90% RH, at 38° C.
In some embodiments, the WVTR is below 1 gr/m2-day, when measured at 90% RH, at 38° C.
In some embodiments, the article is biodegradable.
In some embodiments, the blend of CNC and PVOH is a mixture of CNC and PVOH at a ratio between 0.001:1 to 1:0.001 (CNC to PVOH).
In some embodiments, the ratio is 0.001:1, 0.01:1, 0.1:1, 1:1, 1:0.1, 1:0.01, 1:0.001 w/w, CNC:PVOH.
In some embodiments, the article consists between 3 and 7 material layers, the multilayered structure being of the form ABC, wherein each of A, B and C designate a single layer or two or more layers of a material:
In some embodiments, said layer of CNC-PVOH blend further comprises at least one additional material selected from polyvinyl acetate (PVAc), ethylene vinyl alcohol (EVOH), polyvinyl pyrrolidone (PVP), starch, chitosan, poly acrylic acid (PAA), polyethyleneimine (PEI), carbohydrates, ethylene vinyl acetate (EVA), elastomers, isocyanates, polyurethanes and inert fillers.
In some embodiments, said layer of CNC-PVOH blend consists CNC and PVOH.
In some embodiments, in a structure ABC, layer B comprises a layer of CNC-PVOH blend and a layer of a cellulose nanomaterial selected from nanocrystals (CNC), microfibrillated cellulose (MFC), a combination of CNC and NFC, a combination of CNC and MFC, a blend of CNC with at least one water soluble or water dispersible additive, and a blend of CNC with one or more additional materials selected from polyvinyl alcohol (PVOH), polyvinyl acetate (PVAc), ethylene vinyl alcohol (EVOH), polyvinyl pyrrolidone (PVP), starch, chitosan, poly acrylic acid (PAA), polyethyleneimine (PEI), carbohydrates, ethylene vinyl acetate (EVA), elastomers, isocyanates, polyurethanes and inert fillers.
In some embodiments, any of the material layers comprises at least one additive selected from a polymer, a plasticizer, a surfactant, a particulate material (including nanoparticles and microparticles), a pigment, a carbohydrate, a salt, a conductive material, an oxygen scavenger, lignin and natural extracts.
In some embodiments, the layer CNC-PVOH comprises between 0.1 wt % and 3 wt % impurities of the total weight of the layer, wherein the impurities are selected from carbohydrates and salts.
In some embodiments, the article consisting a layer of a blend consisting of CNC and PVOH; a substrate layer and a cover layer.
In some embodiments, each of layer A and layer C is a paper or paper-based material.
In some embodiments, each of layer A and layer C is of a polymeric material, a polymer coated paper-based material, or a nanocellulose/polymer film.
In some embodiments, layer B is of a thickness of 100 nm-20 μm.
In some embodiments, each of layers A and C is of a material selected, independently of the other, from polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate.
In some embodiments, one or both of layers A and C is a polymer coated paperboard, wherein the polymer is selected from polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate.
In some embodiments, each of layers A and C is of a biodegradable material selected, independently of the other, from polyvinyl alcohol, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polybutylene succinate, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, or any polymer blend of two or more of the aforementioned polymers.
In some embodiments, one or both of layers A and C is a biodegradable polymer coated paperboard, wherein the biodegradable polymer is selected from polyvinyl alcohol, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polybutylene succinate, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, or any polymer blend of two or more of the aforementioned polymers.
In some embodiments, at least one of layers A and C, independently of the other, is or comprises a fabric.
In some embodiments, layers A and B and/or layers B and C are associated with each other directly or separated by an interface material selected from primer material and an adhesive material.
In some embodiments, the multilayered structure is of a form selected from AABCC, ABCC, AABC, AABCBC, ABCBCC, wherein each of A, B and C are as defined in claim 16.
In some embodiments, the article is used in packaging of goods, foods, liquids, and pharmaceuticals.
In some embodiments, the article comprises a substrate of paper or paper based material and a layer of CNC-PVOH blend.
In some embodiments, the article comprises 3 layers: a substrate of a paper or paper based material, a layer of CNC-PVOH blend and a layer of a polymeric water vapor barrier material.
In some embodiments, the article comprises 5 layers: a layer of a polyolefin, a layer of a paper or paper-based material, a layer of CNC-PVOH blend, a layer of a polymeric water vapor barrier material and a further layer of a polyolefin.
In some embodiments, the article comprises 4 layers: a layer of a polyolefin, a layer of a paper or paper-based material, a layer of CNC-PVOH blend and a further layer of a polyolefin.
In some embodiments, the article comprises a paperboard and a layer of CNC-PVOH blend.
In some embodiments, the article comprises 3 layers: a paperboard a layer of CNC-PVOH blend and a layer of a polymeric water vapor barrier material.
In some embodiments, the article comprises 4 layers: a layer of a polyolefin, a paperboard, a layer of CNC-PVOH blend and a further layer of a polyolefin.
In some embodiments, the article comprises 5 layers: a layer of a polyolefin, a paperboard, a second layer of a polyolefin, a layer of CNC-PVOH blend and a further layer of a polyolefin.
In some embodiments, the article comprises a layer of a polyolefin and a layer of CNC-PVOH blend.
In some embodiments, the article comprises 3 layers: a layer of a polyolefin, a layer of CNC-PVOH blend and a layer of a polymeric water vapor barrier material.
In some embodiments, the article comprises 3 layers: a layer of a polyolefin, a layer of CNC-PVOH blend and a further layer of a polyolefin.
In some embodiments, the article comprises a layer of a biodegradable plastic material and a layer of CNC-PVOH blend.
In some embodiments, the article comprises 3 layers: a layer of a biodegradable plastic material, a layer of CNC-PVOH blend and a layer of a polymeric water vapor barrier material.
In some embodiments, the article comprises 3 layers: a layer of a biodegradable plastic material, a layer of CNC-PVOH blend and a further layer of a biodegradable plastic material.
In some embodiments, the article comprises 3 layers: a paperboard, a layer of CNC-PVOH blend and a layer of a biodegradable plastic.
In some embodiments, the article comprises 4 layers: a layer of a biodegradable plastic, paperboard, a layer of CNC-PVOH blend and a further layer of a biodegradable plastic.
In some embodiments, the article comprises 5 layers: a layer of a biodegradable plastic, paperboard, a second layer of a biodegradable plastic, a layer of CNC-PVOH blend and a further layer of a biodegradable plastic.
In some embodiments, the paper or paper-based material is Kraft paper or paperboard.
In some embodiments, the paper or paper-based material is Kraft paper.
In some embodiments, the polymeric water vapor barrier material is styrene, styrene-butadiene, an acrylic polymer or a varnish.
In some embodiments, the polymeric water vapor barrier material is styrene or styrene-butadiene.
In some embodiments, the polyolefin is selected from polypropylene and polyethylene.
In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
In addition to the examples provided above, the following examples should be considered.
The multilayer includes Layer A/Layer B/Layer C
The multilayer structure was transparent, flexible and could be further laminated to include additional layers for the production of flexible or rigid packages with good barrier capabilities. The LDPE layers provided water, water vapor and oil barrier capabilities. The PVOH/CNC inner layer provided gas barrier capabilities.
The multilayer includes Layer A/Layer B/Layer C
The multilayer structure is transparent, flexible, and can be further laminated to more layers for the production of flexible or rigid packages with good barrier capabilities. The Polypropylene layers give water, water vapor and oil barrier capabilities. The PVOH/CNC inner layer gives gas barrier capabilities and improves mechanical properties.
Mechanical properties of the layered structures described in Example 2 were tested by tensile tests, using an Instron machine:
The multilayer includes Layer A1/Layer A2/Layer B/Layer C1/Layer C2
This multilayer structure may be used for rigid packages. The paperboard layer gave mechanical stability, the LDPE layers gave water, water vapor and oil barrier capabilities. The PVOH/CNC inner layer gave gas barrier capabilities:
| Number | Date | Country | |
|---|---|---|---|
| 62678381 | May 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17059085 | Nov 2020 | US |
| Child | 18765463 | US |
