RU2646404C2 - Barrier paper packaging and process for production thereof - Google Patents

Abstract

FIELD: package and storage.

SUBSTANCE: invention relates to a paper bag with barrier properties and a method for manufacturing same. Paper-based composite packaging structure comprises a paper layer and a polyglycolic acid (PGA) filler layer that can be laminated or otherwise adhered to a paper layer to smooth the surface of the paper layer. In some embodiments, the filler layer comprises a polymer or a bio-based polymer. Optional barrier layer may be deposited on one side of the paper layer or filler layer as desired to provide functional barrier characteristics. Composite paper-based film structure(s) may comprise additional layers such as one or more optional primer layers, adhesive layers, ink layers, and/or sealant layers that can be incorporated into the composite film structure as desired to enable the required functional characteristics of the composite film structure described herein.

EFFECT: invention provides a paper-based composite packaging structure that is compostable and/or recyclable and maintains the desirable barrier properties as both the paper and the bio-based polymer filler layers will break down under composting conditions and/or meet standardised recyclability requirements.

23 cl, 3 dwg, 7 tbl, 2 ex

Description

Cross reference to related applications

This application is a partial continuation application with claims for priority being pending patent application US 13/277974 entitled "Metallized Paper Packaging Film and Process for its Production", filed October 20, 2011, the contents of which are fully incorporated into this application .

BACKGROUND OF THE INVENTION

The present invention relates to a flexible paper-based packaging material with acceptable barrier properties for food packaging and to a method for manufacturing such packaging structures.

Description of the prior art

Flexible packaging often uses multilayer film structures made from petroleum products, the source of which is fossil fuels, where their beneficial barrier, sealing properties and the ability to display graphic information are required. The barrier properties of one or more layers of the package are important to protect the product inside it from light, oxygen and / or moisture. This is necessary, for example, to protect foods that are at risk of loss of taste and aroma or deterioration in case of insufficient barrier properties to prevent the passage of light, oxygen or moisture into the package. Typically, the ability to display graphical information is desirable so that the consumer can quickly identify the product that he wants to purchase, and food manufacturers can indicate information such as the nutrient content of the packaged product and place price information such as bar codes on the product packaging.

Prior art flexible packaging typically comprises layers of petroleum-based polymer sheets, such as oriented polypropylene (OPP) or polyethylene terephthalate (PET). When the polymer films do not provide the proper barrier properties, a barrier layer may be deposited onto the surface of one of the inner words of the multilayer film. For example, a metal layer deposited on an inner support layer is capable of providing the required barrier properties. It is well known in the art that when metallizing an oil-based polyolefin, such as OPP, the passage of moisture and oxygen through the film decreases by several orders of magnitude.

The known flexible oil-based film packaging packages account for a relatively small fraction of the total waste generated compared to other types of packaging. Accordingly, their secondary use is uneconomical, taking into account the energy costs of collecting, separating and cleaning the used flexible packaging from the film. Another disadvantage of oil-based films is their resistance to environmental influences and / or biological decay. Consequently, discarded packaging that, through negligence, is outside the planned waste streams, may look like unsightly garbage for a relatively long time. Furthermore, even if such discarded packages fall into the waste stream and end up in landfills, oil-based films are usually stored for a long time, almost without decomposition. Another disadvantage of oil-based films is that they are made from oil-based components, which many attribute to limited non-renewable resources.

Therefore, there is a need for biodegradable and / or recyclable flexible packaging from renewable resources that retains the desired barrier properties. Such flexible packaging should be safe for food and possess the barrier properties that are required for long-term storage of foodstuffs that are stable in storage and low in moisture without losing freshness. Flexible packaging should have the required sealing properties and friction coefficient, which allow it to be used in existing vertical molding, filling and corking machines. Flexible packaging should be designed for disposal in existing disposal systems and / or be compostable.

Summary of the invention

In one embodiment of the present invention, there is provided a paper-based composite packaging structure and a method for manufacturing a paper-based composite packaging structure comprising a paper layer, a filling layer that can be laminated to or otherwise bonded to the paper layer. In some embodiments, the implementation of the filling layer contains a polymer or polymer on a biological basis. An optional barrier layer may optionally be deposited on one side of the paper layer or filling layer to impart functional barrier characteristics. In other contemplated embodiments, the implementation of the paper-based composite film structure (s) may comprise additional layers, such as one or more optional primers, adhesive layers, paint layers and / or sealing layers, which may optionally be included in the composite film structure to impart the desired functional characteristics of the composite film structure described in the invention.

In one embodiment of the present invention, there is provided a paper-based composite packaging structure and a method for manufacturing a paper-based composite packaging structure comprising a silica primer deposited on a filling layer containing polyoxyalkanoate (PHA), polylactic acid (PLA), or another biopolymer which is applied to the paper layer by conventional extrusion or coating methods that are known in the art. An optional sealing layer may also be optionally applied to one side of the paper layer to impart a sealing ability. Alternative embodiments of the present invention optionally include the use of additional optional layers containing metal, metalloid, ethylene-polyvinyl alcohol copolymer (PVOH), polyglycolic acid (PGA), ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), amorphous PLA (aPLA ), wax, starch and / or colorful layers and deposited, layered, deposited or otherwise bonded or associated with the above-described composite film structure.

In one embodiment of the present invention, there is provided a paper-based composite film and a method for manufacturing a paper-based composite film which is monolithic, containing a primer layer, a PHA layer and a paper layer. Alternative embodiments optionally include the use of additional optional layers containing metal, metalloid, PGA, PVDC, amorphous PLA, PHA, wax, polyester and polyester copolymer, adhesives, sealants and / or colorful layers and applied, layered, deposited or otherwise bonded or bonded to the above-described composite film structure.

In one embodiment, the invention provides a paper-based composite film and a method for manufacturing a paper-based composite film comprising a paper layer and a PGA layer deposited on at least one side of the paper layer. Alternative implementation options optionally include the use of additional optional layers containing primers, sealants, adhesives, paints and / or barrier layers and deposited, layered, deposited or otherwise bonded or associated with the above-described composite film structure.

In one embodiment, the invention provides a paper-based composite film and a method for manufacturing a paper-based composite film comprising a paint layer, a starch layer and a paper layer. Alternative embodiments optionally include the use of additional optional layers containing metal, metalloid, polyester, copolymer of polyester, PGA, amorphous PLA, PHA, wax, polyester and copolymer of polyester, and / or other layers deposited, layered, deposited or otherwise bonded or bonded to the composite film structure described above.

Listed, as well as additional features and advantages of the present invention are disclosed in the following detailed description.

Brief Description of the Drawings

The appended claims set forth the alleged novelty features characterizing the invention. However, the invention itself, as well as the preferred method of its application, its additional tasks and advantages will be best understood from the following detailed description of illustrative embodiments with reference to the accompanying drawings, in which:

in FIG. 1 shows an enlarged schematic cross-sectional view of a multilayer flexible packaging according to one embodiment of the invention,

in FIG. 2 shows an enlarged schematic cross-sectional view of a multilayer flexible packaging according to one embodiment of the invention, and

in FIG. 3 shows an enlarged schematic cross-sectional view of a multilayer flexible packaging according to one embodiment of the invention.

Detailed description

The present invention provides a recyclable and / or compostable paper-based multilayer composite packaging. In the various described embodiments, the paper-based composite packaging is compostable and / or recyclable, since both the paper layer and the bio-based polymer filling layer decompose under composting conditions and / or meet the requirements for recyclability. Paper-based composite packaging is applicable for recycling in typical waste paper processing processes, which are described below.

Paper-based products are usually reused as recycled materials by mechanical re-cooking methods. Essentially, any polymer used in a paper-based product should be compatible with existing mechanical re-cooking methods. The paper may also be chemically re-boiled prior to mechanical re-boiling. In chemical re-cooking, caustic soda, bleaches or other chemicals are usually used to dissolve or otherwise remove contaminants or polymer coatings from the surface of the paper. Since polymers bind paper fibers when applied to the surface of paper polyethylene (PE) or polypropylene (PP), when they are separated by mechanical re-cooking methods, more than 15% by weight of paper fibers is usually lost due to the polymer sticking to some paper fibers and re-cooking time takes them away in the waste stream. For this reason, most paper mills refuse to accept recycled polymer coated paper.

Caustic washing during re-cooking does not decompose polyethylene and other polyolefins because of their high resistance to chemical attack. However, PGA, PHA, PLA, and other biologically based polymers become soluble under conditions of depolymerization of condensation polymers, which makes the chemical bonds between the polymers vulnerable to chemical attack by NaOH and other substances. The polymerization of PGA, aPLA and PHA leads to the removal of water molecules from the forming chemical structure. However, this chemical reaction can be reversed by adding water to the polymer. Accordingly, the addition of water, exposure to heat (to provide energy) and chemicals (e.g. NaOH) during the re-cooking process removes the polymer or at least reduces the loss of paper fibers compared to using polyethylene and polypropylene. Certain compostable polymers related to non-renewable resources, such as aliphatic polyesters with bioavailable and degradable chemical bonds, may also be used in the present invention.

In the various described embodiments of the present invention, the amount of material required to impart barrier properties to paper-based flexible packaging has been reduced. Accordingly, the present invention provides a flexible paper-based packaging having a multilayer structure comprising a paper layer, a filling layer, a primer layer and / or a barrier layer on a paper-based flexible composite film. The multilayer packaging structure may optionally contain an adhesive layer, a sealing layer and / or a paint layer. In the described embodiments, the implementation provides for the use of flexible paper-based packaging structures sufficient as packaging material for storage-stable food and snack products with a low moisture content. In some embodiments, such a paper-based flexible packaging provides recyclable and / or compostable flexible packaging for food and snack foods.

The term "packaging" used in the description should be understood as any container in the form of a flexible multilayer packaging. Such a desired package provides oxygen impervious barrier properties and has an oxygen transmission rate of less than about 10 cubic cm / m ² / day, preferably less than about 5 cubic cm / m ² / day, more preferably less than about 2 cubic cm / m ² / day. Such a desired packaging provides moisture impervious barrier properties and has a water vapor transmission rate of less than about 1.0 gram / m ² / day, preferably less than about 0.5 gram / m ² / day, more preferably less than about 0.1 gram / m ² / day. The packaging structures described in the invention are particularly useful for making flexible packaging for snack foods such as potato chips, corn chips, tortilla chips, and the like. Nevertheless, although the layers and various structures described in the invention are designed to be used in packaging operations for snack foods, such as filling and capping bags of snack foods, the packaging structures described in the invention may also find application in various packaging techniques for other low-moisture foods .

Typical obstacles encountered in the past in technology when attempting to apply a barrier layer to a paper substrate were generated by the structure of the paper itself. In the process of making paper, individual fibers are pressed (usually from plant materials) and dried to obtain flexible sheets of paper. When analyzing the topology of the paper surface using an approximate method, such as optical microscopy, a sheet of paper looks like a network of bound fibers. The paper has not a continuous, but a porous structure of compressed and bonded cellulose fibers. Paper porosity is defined as the volume fraction of all voids existing in a sheet of paper and can be measured by the known compressed air test method according to IPC TECHNICAL PAPER SERIES NUMBER 183 (http://smartech.gatech.edu/ispui/bitstream/1853/2665/l/ tps-183.pdf) or TAPPI T460 (with low air resistance) and T536 (with high air resistance) methods. Since untreated paper is a highly porous material, its porosity should be reduced to the level of polymer and plastic films to at least be considered as a likely barrier to gases and vapors. Fillers and adhesives significantly reduce paper porosity up to the formation of a continuous surface. This technology has traditionally been used to produce a higher quality print surface. Using the same methods, they give a paper surface of similar quality to low-grade or commercial polymer films. When examined with a device with high sensitivity or high magnification, such as an atomic force microscope (AFM) or scanning electron microscope (SEM), it is clear that this paper surface filled with low-quality polymer films has a strong roughness. You can clearly see the rough surface of the filler fibers. Filler fibers look like peaks or plateaus, and the space between them looks like troughs, which generally creates a rough surface topology with a high degree of variability. The surface roughness of the paper layer used in the invention is calculated as the average height difference between the peaks and troughs on the surface of the paper layer. Roughness measurements known from the art can be performed using the RMS method using images obtained using an atomic force or optical microscope.

Attempts made in the past to apply a barrier layer to a sheet of paper generally did not result in a packaging structure capable of providing acceptable barrier properties. This is mainly due to the high porosity of the paper. Adhesives and other substances reduce the porosity of the paper to such an extent that it becomes an applicable basis for applying barrier layers. After the surface of the paper becomes solid, the next step in creating a paper with a protective coating is to reduce the surface roughness to acceptable levels. In the context of the various described embodiments of the invention, paper with acceptable low porosity is paper through which 10 ml of air penetrates in 200 seconds or more (Gurley index) when tested with the TAPPI T536 method. This provides a continuous surface, applicable for applying additional layers in order to obtain impermeable to gas and vapor barrier layer. Surface integrity can also be checked by optical microscopy, AFM or SEM.

When attempting in the past to apply a barrier layer to a sheet of paper due to the high roughness of the paper surface (i.e., the height difference between the peaks and troughs of the filled paper substrate), particles of the deposited barrier layer accumulated at the peaks, which prevented the uniform distribution of the barrier layer particles in the troughs . Accordingly, although some particles of the barrier layer could adhere to portions of depressions on the surface of the paper, the deposition of a continuous barrier layer of an appropriate uniform depth covering the peaks and depressions on the surface of the paper substrate and imparting acceptable barrier properties to flexible paper-based packaging remained difficult. The question of the covering power of the barrier layer arises especially sharply when the difference between peaks and troughs or the distance between adjacent peaks exceeds the desired thickness of the barrier layer (usually 40 nanometers or less).

In the process of creating the described invention, it was found that an effective barrier layer can be applied to the paper substrate if the surface of the paper is sufficiently smoothed or filled before applying the barrier layer. In one embodiment, a paper layer is smoothed whose surface roughness exceeds the desired thickness of the barrier layer deposited on its surface so that the surface roughness becomes smaller than the desired thickness of the barrier layer. In one embodiment, the surface roughness of the smoothed paper is less than half the desired thickness of the barrier layer.

As used herein, the term “barrier” refers to any applicable moisture and oxygen impervious barrier material to reduce or predominantly prevent the passage of oxygen and water vapor through the packaging structure. The barrier layer may include, without limitation, metal, metal oxide, metalloid oxide and / or combinations thereof. Such a barrier layer may be applied by any suitable method known in the art, including, without limitation, vaporization, sputtering, chemical vapor deposition (CVD), chemical vapor deposition during combustion (CCVD), physical vapor deposition (PVD), plasma - chemical vapor deposition (PECVD), vacuum deposition, gas-plasma deposition and gas-plasma hydrolysis deposition. In the described alternative embodiments, the implementation can also apply existing coating technologies capable of imparting sufficient barrier properties to the barrier layer, such as applying PVDC, EVOH, PVOH or various known acrylic materials such as polyethylene acrylic acid (EAA), polymethyl methacrylate (PMMA), polyacrylic acid , polycyanoacrylate, hydroxyethyl methacrylate and polyethyl methacrylate, in order to form an effective barrier layer.

One of the available methods to smooth the surface of the paper substrate is to apply a filling layer to the surface of the paper. Examples of fillers that can be applied to the paper backing include marls, such as kaolinite, talc, mica, mordenite, vermiculite, titanium dioxide and calcium carbonate. Natural or synthetic binders such as waxes, starches, vinyls, acrylics, proteins or latex can be used to adhere the filler to the surface of the paper. The filler may also contain dispersants to facilitate particle separation, antifoam agents to remove foam from colored fillers, reducing the solubility of agents to increase water resistance, preservatives to reduce bacterial growth, lubricants to reduce the coefficient of friction of paper and / or polymer resins.

As a result of applying filler to the surface of the paper, the resulting paper has a smoother surface than before applying filler. In the various described embodiments, the filler can act as a primer layer, increasing the surface energy of the coated paper layer and thereby increasing the adhesion strength of the barrier layer to the primed paper layer of the composite packaging structure. In the various embodiments described, the filler is a predominantly bio-based compostable polymer. Used in the description, the term "polymer on a biological basis" refers to a polymer, at least 80% by weight of which consists of raw materials. In one embodiment, the biological-based polymer may contain up to about 20% of a conventional polymer, the source of which is oil.

Table 1 presents various materials and resins that can be used in the construction of packages according to various embodiments of the described invention, and their respective suitability for composting and / or recycling. The composting environment is further characterized as a marine environment and a typical domestic or “home” composting environment. Composting is commonly known as the process of decomposing organic matter into compost or humus, rich in nutrients for soil and plants. Compost can be used as a soil improver, fertilizer for plants and soil, and a natural pesticide for soil.

Recycling usually means the ability to recycle used materials or waste into new products in order to avoid the loss of such potentially recyclable materials. Recycling reduces the consumption of new raw materials, energy consumption and environmental pollution associated with the production of products. Recycling is currently one of the key components of waste reduction. When creating paper-based packaging for food products from one or more of the materials described in the invention, garbage generation is minimized, the volume of landfills occupied by such used packages is reduced, while such packaging is fully or partially compostable, recyclable, or and another, as can be seen from Table 1, which presents various materials and resins.

Table 1 shows examples of biologically based polymers compostable and / or recyclable polymers that can be used as filler in the described embodiments, and are described in more detail below. For example, PLAs are obtained from plant materials, including soybeans, as described in US 2004/0229327, or by fermentation of agricultural by-products, such as corn starch, or other plant materials, such as corn, wheat, or sugar beets. A film can be obtained from PLA, as well as from most thermoplastic polymers. PLA has physical properties similar to those of PET and has excellent transparency. PLA films are described in US Pat. No. 6,207,792, and PLA resins are commercially available from Natureworks LLC (http://www.natureworksllc.com) (Minneton, Minnesota, USA). The decomposition of PLA produces carbon dioxide and biomass. The PLA films used in accordance with the present invention are predominantly insoluble in water under ambient conditions, but easily decompose under typical composting conditions.

PHA is a polymer belonging to the class of polyesters, and can be produced by microorganisms (for example, Alcaligenes eutrophus) as a form of energy storage. In one embodiment, the microbial biosynthesis of PHA begins with the condensation of two acetyl-CoA molecules, resulting in the formation of acetoacetyl-CoA, which is subsequently reduced to hydroxybutyryl-CoA. Then, hydroxybutyryl-CoA is used as a monomer for the polymerization of PHB, which is the most common type of PHA. PHA is marketed by various suppliers, such as Metabolix (Cambridge, Mass., USA). In the various described embodiments, the PHA can be used as a filling layer, a barrier layer and / or a sealing layer of the paper-based flexible composite packaging structures described in the invention.

PGA is a degradable and compostable thermoplastic polyester compatible with mechanical re-cooking processes that accompany waste paper recycling. PGA is marketed by the Japanese company Kureha, which manufactures and sells PGA under the trademark KUREDUX. In some embodiments, PGA can also be used as a filling layer, an oxygen-impervious barrier layer and / or a sealing layer of the paper-based flexible composite packaging structures of the invention.

Table 2 provides a list of various embodiments of the invention, illustrating many flexible packaging structures containing the paper layer described in the invention. In accordance with the present invention, such composite packaging structures are predominantly insoluble in water at ambient conditions, but readily decompose under typical composting conditions. For information, it should be noted that the elements of the packaging structures are shown in order from left to right, which means that the leftmost layer of the composite package is facing the external environment, and the rightmost layer is facing the internal environment or the side of the product inside the package.

As shown in Table 2, [SiO (x)] denotes a silicon dioxide layer that is deposited as a primer or barrier layer by CCVD or PECVD or by any other method known in the art and / or described in the invention. In some embodiments, a silica layer is deposited as a primer or barrier layer by CCVD or PECVD in an open environment. [Al (2) O (3)] refers to an alumina layer that has been deposited as a primer or barrier layer by conventional metallization, CCVD or PECVD, or by any other method known in the art. In some embodiments, an alumina and / or silica layer is deposited by CCVD or PECVD in an open environment. X denotes various polymers that can be used as one or more filling layers, including without limitation PLA, PHA, PGA and other polymers known from the art. The abbreviation PVDC refers to a polyvinylidene chloride layer, which can provide additional functionality to the barrier layer, as described in the various described embodiments. The term “adhesives” refers to solvent based adhesives such as polyvinyl acetate, hot melt adhesives such as ethylene vinyl acetate, or solvent free adhesives such as polyurethanes. The term "ink" means any printing ink (s) on the market that can be used to print on food packaging. The term “paper” refers to any paper backing, such as wrapping paper, coated paper, magazine paper or photo paper or other types of pulp paper that are commercially available, and paper structures processed by paper-making methods such as calendering or gloss to give a smoother surface. The term “sealant” refers to a sealant layer, including without limitation a “heat sealable” layer, which may consist of PHA, amorphous PLA, wax, starches, PGA and / or commercially available sealants such as ECOFLEX or ECOVIO, which is a compostable polyester manufactured by BASF. Heat sealing activators can also be used in the heat-sealing layer, which are used in technology to increase the heat-sealing strength and the range of welding temperatures and are available on the market. Table 2 shows the various configurations of composite packaging structures, including monopoly without a paint layer (structures 1-A to 1-O), monopoly with a paint layer (structures 1-P to 1-AA), structures with a laminated barrier layer (structures from 1-BB to 1-GG) and structures with a metallized primer layer (structures from 1-LV to 1-MM).

In FIG. 1 is an enlarged cross-sectional view of a paper-based flexible packaging 100 according to the present invention. It is shown that the paper layer 112 is coated on one side with the filling layer 114. An optional primer layer 116 may be applied to the opposite side of the paper layer 112 to increase surface energy and improve adhesion to the optional barrier layer 118. The barrier layer 118 may be applied by any known technique applicable method, including without limitation evaporation, spraying, chemical vapor deposition (CVD), chemical vapor deposition during combustion (CCVD), physical vapor deposition (PV D), plasma-chemical vapor deposition (PECVD), vacuum deposition, gas-plasma deposition and gas-plasma hydrolysis deposition. In alternative embodiments, barrier layer 118 may be applied by CCVD or PECVD in an open environment without the need for a vacuum or pressure chamber. In alternative embodiments, for deposition of the primer layer in order to activate adhesion of the barrier layer to the paper layer, smoothing the surface of the paper layer to improve the deposition of the barrier layer and / or to impart the functional properties of the barrier layer, conventional methods using a spiral roller scraper, engraving and other known methods can be applied. coating. An optional heat sealable layer 120 is shown, which serves to seal the flexible packaging as it passes through vertical molding, filling and capping machines (VFFS) and other packaging equipment.

In alternative embodiments, known coating methods can also be applied to provide barrier layer 118 to provide sufficient barrier properties, such as applying polyvinylidene chloride (PVDC), ethylene-vinyl alcohol copolymer (EVOH), ethylene-polyvinyl alcohol copolymer (PVOH), or various acrylic materials such as polyethylene acrylic acid (EAA), polymethyl methacrylate (PMMA), polyacrylic acid, polycyanoacrylate, hydroxyethyl methacrylate and polyethyl methacrylate are known E in the art and / or described herein.

In one of the embodiments illustrated in FIG. 1, a primer layer 116 is applied in the form of a solution containing EAA and PVOH, which is applied in liquid form to the surface of the paper layer 112, and then dried to smooth the surface of the paper 112. For example, the solution may contain 0.1-20% PVOH and EAA and 80-99.9% of water. In one embodiment, approximately equal amounts of PVOH and EAA are used. In one embodiment, the solution contains about 90% water, about 5% PVOH, and about 5% EAA. In this way, a smoothed and / or activated primer layer 116 is obtained that improves the deposition and adhesion of the barrier layer 118. An optional heat seal layer 120 may also be used. In one embodiment, the heat seal layer 120 comprises an amorphous PLA, such as 4060 PLA manufactured by Natureworks. An optional ink layer can be applied to the side of the paper layer, opposite the fill and primer layers. In alternative embodiments, the implementation of the paint layer can be applied to the side of the filling layer, opposite the barrier layer. The ink layer may contain a product logo, graphics, nutrient information, or other printed information.

In one embodiment, the primer 116 contains EVOH, the composition of which can vary from EVOH with a low degree of hydrolysis to EVOH with a high degree of hydrolysis. The following are EVOH formulas according to various embodiments of the present invention.

In the context of the present invention, EVOH with a low degree of hydrolysis corresponds to the above formula in which n = 25. In the context of the present invention, EVOH with a high degree of hydrolysis corresponds to the above formula, in which n = 80, with n being the molar percentage of vinyl alcohol in the composition. Primer layer 116 containing EVOH may be extruded onto a smooth surface of the paper, and barrier layer 118 may be applied by methods known in the art and as listed above. In other described embodiments, the primer 116, 214, 320 shown in FIG. 1, 2 and 3, may be a coating of PVOH or amorphous PVOH, in liquid form, applied to the side of the paper filler, and then dried before applying an optional barrier layer. Then, a barrier layer 118, 318 may be applied to the primer layer 116, 320, as shown in FIGS. 1 and 3.

In one embodiment, a composite packaging structure is provided comprising a bio-based film and a paper structure, wherein the PHA layer acts as a filler and sealant. The layers of paper and PHA can be laminated using standard industrial techniques known from the art, such as extrusion lamination, extrusion coating, watering, water-based coating, using solvent based adhesives, polyurethane adhesives and / or solvent-free adhesives. The surface of the PHA layer, opposite the surface of the paper, may optionally be coated with amorphous PVOH, PVOH, EVOH, maleic anhydride or other suitable coatings sufficient to impart acceptable barrier properties to the PHA layer applicable in food packaging.

In one embodiment, the filling layer does not function as an adhesive layer. Instead, a primer is applied to the surface of the paper by extrusion before applying the barrier layer. The primer layer consists of an applicable material containing polar chemical groups, and also acts as a surface modifier that provides a predominantly smooth surface and / or increases surface energy when applying and holding the barrier layer, such as the barrier layer 118 shown in FIG. 1. Examples of useful primers that can be used in various embodiments of the present invention include, but are not limited to, epoxide, maleic anhydride, ethylene methacrylate (EMA), polyethyleneimine (PEI), and ethylene vinyl acetate (EVA).

Table 3 presents various embodiments of a flexible composite packaging structure using a paper backing, PGA, amorphous PLA (aPLA), PVOH and / or wax. For information, it should be noted that the elements of the packaging structures are shown in order from left to right, which means that the leftmost layer of the composite package is facing the external environment, and the rightmost layer is facing the internal environment or the side of the product inside the package.

As shown in Table 3, [SiO (x)] denotes a silica layer that is deposited as a primer or barrier layer by CCVD or PECVD or other methods known from the art. In some embodiments, a silica layer is deposited as a primer or barrier layer by CCVD or PECVD in an open environment. [Al (2) O (3)] means an alumina layer that has been deposited as a primer or barrier layer by conventional metallization, CCVD or PECVD, or by any other method known in the art or described in the invention. In some embodiments, an alumina and / or silica layer is deposited by CCVD or PECVD in an open environment. The term "ink" means any printing ink (s) on the market that can be used to print on food packaging. The term “paper” refers to any paper backing, such as wrapping paper, coated paper, magazine paper or photo paper or other types of pulp paper that are commercially available, and paper structures processed by paper-making methods such as calendering or gloss to give a smoother surface. The term “sealant” refers to a sealant layer, including but not limited to a “heat sealable” layer, which may consist of polybutyl succinate (PBS), PHA, aPLA, wax, starch, PGA, aliphatic polyester and / or commercially available sealants such as ECOFLEX or ECOVIO, which is a BASF compostable polyester. Heat sealing activators can also be used in the heat sealable layer to increase the heat sealing strength and the range of welding temperatures. The various configurations of the composite packaging structures presented in Table 3 include paper and PGA structures (structures 2-A to 2-M), paper structures and PVOH (structures 2-N to 2-0), and paper structures and wax (structures 2-P to 2-R).

In FIG. 2 illustrates one embodiment of the paper-based composite packaging structure 200 described in the invention. It is shown that the paper-based composite structure 200 comprises a paper layer 212, a fill layer 214, a paint layer 216, and a primer layer 218. In this embodiment, the primer layer 218 contains a silicon dioxide layer or a plurality of silicon dioxide layers deposited by a known CCVD or PECVD to form a high energy surface for applying a metal barrier layer (not shown) to primer 218. In one alternative embodiment, instead of primer 218, wasp provide a barrier layer of [Al (2) O (3)]. It is applied to the paint layer 216 on the surface of the fill layer 214, which in various embodiments may comprise PHA, PLA, PET, or a layer of any other applicable biological-based film. The filling layer 214 may be applied to the surface of the paper layer 212 by conventional extrusion techniques known in the art.

As shown in FIG. 2, in one embodiment, any polymer or polymer blend that has a biologically based film orientation, relatively smooth surface, and polar chemical groups can be used as filling layer 214. Polar chemical groups are desirable in the filler because they are attracted to the metal or metalloid barrier layer, and it is assumed that polar chemical groups, such as hydroxyl groups, form covalent bonds to form metal oxide or metalloid oxide after metallization. Mixtures of alcohols, which include a copolymer of ethylene and vinyl alcohol (EVOH) and polyvinyl alcohol (PVOH), as well as polymers containing polar amide groups such as nylon, are desirable. In addition, amorphous PET (APET), polyethylene terephthalate glycol (PETG) and PGA containing polar carbonyl groups can also be used as fillers. Accordingly, in the various embodiments described, the filling layer 214 may comprise one or more prior art polar substrates selected from amorphous PET, PETG, APET, PGA, various nylons, including amorphous nylon, EVOH, nylon / EVOH mixtures, PVDC, PVOH, amorphous PVOH (aPVOH) and / or a mixture of PVOH / ethylene acrylic acid (EAA).

In one embodiment, a paper and PGA structure can be created using standard industrial techniques, such as extrusion coating. A paper and PGA structure can also be created by producing a plastic film from a PGA monolayer or a multilayer coextruded film containing an outer layer of PGA. This structure can be created by traditional methods known from the technique of casting from a solution or blowing. Examples of polymers that can be used in coextruded structures include polyesters such as PLA, ECOFLEX, ECOVIO, and other possible polymer blends. The film of paper and PGA can then be combined using currently known extrusion lamination or adhesive lamination techniques to form a paper / PGA structure. The PGA structure may consist of 100% PGA (such as Kureha's 100E35 brand PGA) or PGA with fillers such as calcium carbonate or PGA with voids (foamed films formed by chemical or physical methods during the manufacturing process).

Example 1

Extruded PGA 100E35 with a thickness of 1.2 mil on two paper substrates. The paper substrates used were (a) # 25 CIS grade Verso paper and (b) # 25 glossy paper with a coat of Thilmany mica primer H722 (1.7 g / sq. M). Both samples were metallized using traditional vacuum metallization methods. To control the degree of metallization used rakord of PET. The target optical density of the pet film was 2.3. The following results were obtained.

Example 1

Data set

Example 2

PGA was coextruded onto a PLA film to test barrier potential. Co-extruded a PGA / PLA film in a three-layer configuration with a PGA overlay, a PLA core (NatureWorks 4032) and a sealant layer from PLA (NatureWorks 4060). The combined polymer structure was extruded through a matrix with a melting point of 440 ° F. The film was passed through a set of cooling cylinders and oriented in the longitudinal direction in a single-stage longitudinal orientation device (MDO). Then the film was passed through the orientation device in the transverse direction using chain valves and a furnace. Then the film was cut lengthwise into sections of the desired width and length, wound, and some samples were metallized. The following results were obtained.

Example 2

Table of conditions for Example 2

In one embodiment of the invention, a composite packaging structure is provided comprising a paper layer with a PGA laminated layer that is formed by extrusion coating methods known in the art. The paper and PGA structure can also be formed using a plastic film from a PGA monolayer or a multilayer coextruded film using PGA as one of its outer layers, which can be made by known solution casting or blow molding methods. Polymers that can be used in the manufacture of this composite structure include PLA, aliphatic polyester and other mixed polymers. The paper layer and the PGA layer are then combined by extrusion lamination or adhesive lamination to form a composite packaging structure of paper and PGA. In other embodiments, a metal barrier layer or a silicon dioxide primer or barrier layer may be applied to the paper and PGA composite structure to form an optional barrier or primer layer. In one embodiment of the present invention, biologically based polymers or compostable (according to ASTM D6400) polymers are used as filling, primer and / or heat sealable layers in a paper-based composite structure. In one embodiment, in which the filler also acts as a primer, it has been found that such a three-layer structure is capable of imparting appropriate barrier properties to paper for use in food packaging.

In FIG. 3 illustrates one embodiment of the paper-based composite packaging structure 300 described in the invention. As shown in FIG. 3, an ink layer 312 is applied to the paper layer 314. An adhesive layer 316 is placed between the paper layer 314 and the barrier layer 318. To improve the adhesion of the barrier layer 318 to the filling layer 322, a primer layer 320 is used. The paper layer 324 and the filling layer 326, which is laminated, coextruded or otherwise applied onto it, generally form a paper-based composite packaging structure 300. In this embodiment, an ink layer 312 is applied to the surface of the paper layer 314. The ink layer 312 contains any well-known printing inks suitable for use in food packaging. An adhesive layer 316 is applied to the opposite surface of the paper layer 314 to which the barrier layer 318 is adhered. The barrier layer 318 may comprise aluminum, silicon dioxide, a foil, or a barrier of other applicable metals or metalloids. An optional primer layer 322 may optionally be applied to the fill layer 322 to improve adhesion between the primer layer 320 and the barrier layer 318. The primer layer 320 can be applied to the paper layer 322 by CCVD or PECVD or other conventional primer methods known in the art. Primer layer 320 can also be applied to paper layer 322 by known CCVD or PECVD in an open environment.

In various embodiments of the present invention, the amount of material required to obtain a paper-based film with barrier properties is reduced. When the filling layer also acts as a primer, only three layers are required to give the paper the proper barrier properties. For example, Table 4 shows various embodiments of flexible composite packaging structures using paper and starch. For information, it should be noted that the elements of the packaging structures are shown in order from left to right, which means that the leftmost layer of the composite package is facing the external environment, and the rightmost layer is facing the internal environment or the side of the product inside the package.

As shown in Table 4, [SiO (x)] denotes a silica layer that is deposited as a primer or barrier layer by CCVD or PECVD or by any other method known in the art and / or described in the invention. In some embodiments, a silica layer is deposited as a primer or barrier layer by CCVD or PECVD in an open environment. [Al (2) O (3)] refers to an alumina layer that has been deposited as a primer or barrier layer by conventional metallization, CCVD or PECVD, or by any other method known in the art. In some embodiments, an alumina layer is deposited by CCVD or PECVD in an open environment. The term "starch" refers to starch-based thermoplastic polymers that contain a plasticizer, such as glycerin, which allows starch to be processed like a plastic resin, and which can be extruded in a reactive manner with other compounds to increase heat resistance. The term “adhesives” refers to solvent based adhesives such as polyvinyl acetate, hot melt adhesives such as ethylene vinyl acetate, or solvent free adhesives such as polyurethanes. The term "ink" means any printing ink (s) on the market that can be used to print on food packaging. The term “paper” refers to any paper backing, such as wrapping paper, coated paper, magazine paper or photo paper or other types of pulp paper that are commercially available, and paper structures processed by paper-making methods such as calendering or gloss to give a smoother surface. The term “sealant” refers to a sealant layer, including without limitation a “heat sealable” layer, which may consist of PHA, amorphous PLA, wax, starches, PGA and / or commercially available sealants such as ECOFLEX or ECOVIO, which is a compostable polyester manufactured by BASF. Heat sealing activators can also be used in the heat sealable layer to increase the heat sealing strength and the range of welding temperatures. Table 4 presents various configurations of paper-based composite packaging structures, including paper and starch structures (structures 3-A to 3-C), paper, starch structures and a metal primer or barrier layer (3-D structures 3E), structures using paper, starch, and a primer or barrier layer of metal oxide (structures 3-F to 3-H), structures using paper, starch, and a barrier layer of m foil (structures 3-I by 3-K) and structures using paper, starch and metallized barrier layer (structure 3-L 3-N).

In some contemplated embodiments of the described invention, a multilayer flexible packaging is provided comprising: (a) a paper layer; (b) a filling layer deposited on at least one surface of the paper layer to smooth at least one surface of the paper layer; and (c) an optional primer layer deposited on the surface of the filling layer, wherein the primer layer promotes metallization of the flexible packaging. In some contemplated embodiments of the described invention, a multilayer flexible packaging is provided comprising: (a) a paper layer; (b) an optional ink layer deposited on the first side of the paper layer; and (c) a polyglycolic acid (PGA) layer deposited on the second side of the paper layer. In some of the considered embodiments of the described invention, there is provided a method for manufacturing a multilayer flexible packaging, comprising: (a) applying a filling layer to a paper layer to smooth at least one surface of the paper layer; and (b) deposition of the primer layer on the filling layer.

Unless otherwise specified, all the scientific and technical terms used in the description have the meaning generally accepted among specialists in the field of technology to which the present invention relates. All cited sources are incorporated by reference into this application; however, if such sources, including those from priority documents, contradict the present invention, preference is given to the present invention. Although the invention is specifically illustrated and described with reference to preferred embodiments, those skilled in the art will understand that various changes in form and detailed content may be made therein without departing from the spirit of the invention.

Claims (25)

1. A multilayer flexible packaging, characterized in that it contains a paper layer and a polyglycolic acid (PGA) filling layer deposited on at least one surface of the paper layer to smooth at least one surface of the paper layer, and a primer deposited on the surface of said filling layer, while the primer layer improves the wettability of the primed surface. 2. The flexible packaging of claim 1, wherein the paper is selected from the group consisting of brown paper, coated paper, or heavy paper. 3. The flexible packaging according to claim 1, in which the primer layer is selected from the group consisting of: metal, metal oxide, silicon dioxide, polyethylene acrylic acid (EAA), a copolymer of ethylene and vinyl alcohol (EVOH), a copolymer of ethylene and polyvinyl alcohol (PVOH) , epoxide, maleic anhydride, ethylene methacrylate (EMA), polyethyleneimine (PEI) and ethylene vinyl acetate (EVA). 4. The flexible packaging of claim 1, further comprising a sealing layer that is selected from the group consisting of: polyoxyalkanoate (PHA), polybutyl succinate (PBS), amorphous polylactic acid (aPLA), wax, starch, PGA and aliphatic polyester. 5. The flexible packaging of claim 1, further comprising a paint layer deposited on the first side of the paper layer, wherein the PGA layer is deposited on the second side of the paper layer. 6. The flexible packaging of claim 1, further comprising a barrier layer. 7. The flexible packaging of claim 6, wherein the barrier layer is selected from the group consisting of: inorganic metal oxide, metal, alumina, silicon dioxide, foil, polyvinylidene chloride (PVDC), EVOH, PVOH, EAA, polymethyl methacrylate (PMMA), polyacrylic acid, polycyanoacrylate, hydroxyethyl methacrylate and polyethyl methacrylate. 8. The flexible packaging of claim 1, further comprising an adhesive layer that is selected from the group consisting of: polyvinyl dichloride (PVDC), polyvinyl acetate, ethylene-vinyl acetate, or polyurethanes. 9. The flexible packaging of claim 1, wherein the filler comprises a binder. 10. The flexible packaging of claim 1, wherein the primer is applied by CCVD or PECVD in an open environment. 11. The flexible packaging of claim 6, wherein the barrier layer is applied by chemical vapor deposition during combustion (CCVD) or plasma-chemical vapor deposition (PECVD) in an open environment. 12. The flexible packaging of claim 1, which is predominantly compostable. 13. The flexible packaging according to claim 1, which is mainly suitable for recycling. 14. A method of manufacturing a multilayer flexible packaging, characterized in that it contains the stages: applying a polyglycolic acid (PGA) filling layer to the paper layer to smooth at least one surface of the paper layer; deposition of the primer layer on the filling layer of PGA. 15. The method according to p. 14, in which the filling layer and the paper layer are laminated by applying a binder. 16. The method of claim 15, wherein the binder is selected from the group consisting of: waxes, starches, vinyls, acrylic materials, proteins and latex. 17. The method according to p. 14, in which the primer layer is deposited in one of the methods, including: CCVD, PECVD, CCVD in an open environment, PECVD in an open environment, coating from a solution, using a spiral roller scraper or engraving. 18. The method according to p. 14, further comprising applying a paint layer to at least one surface of the paper layer. 19. The method according to p. 14, further comprising deposition of the barrier layer on the surface of the primer layer. 20. The method according to p. 14, further comprising applying a sealing layer. 21. The method according to p. 19, in which the barrier layer is deposited in one of the methods, including: evaporation, sputtering, vapor deposition (CVD), CCVD, PECVD, CCVD in an open environment, PECVD in an open environment, coating from a solution, use of a spiral roller scraper or engraving, vacuum deposition, gas-plasma deposition, and gas-plasma hydrolysis deposition. 22. The method according to p. 19, in which the barrier layer is selected from the group comprising: metal oxide, metalloids, PVDC, EVOH, PVOH, EAA, acrylic materials, PMMA, polyacrylic acid, polycyanoacrylate, hydroxyethyl methacrylate and polyethyl methacrylate. 23. The method according to p. 14, in which the primer layer is selected from the group comprising: metal, metal oxide, silicon dioxide, EAA, PVOH, amorphous PVOH, epoxide, maleic anhydride, EMA, PEI and EVA.

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