Patent Application
20250162293
The present invention relates to a multilayer film adapted for vacuum packaging and to a process of manufacturing said multilayer film. The invention also concerns packages, optionally vacuumized packages, optionally vacuum skin packages, for containing products, for example food products. The invention furthermore relates to a process and to an apparatus for manufacturing the mentioned vacuum packages using one or more of said multilayer films.
Plastic films are widely used, optionally in the food industry, to form packages. For example plastic films are used to wrap a product or to form a bag into which the product is inserted or for closing a tray hosting the product.
Plastic films are designed in order to present specific technical effects functional to the type of package or product to be packaged.
For example, in certain applications it may be desirable to reduce adhesion of the product to the inner surface of the package. In this respect, documents EP2397319B1 and EP2857190B1 (Toyo) describe multilayer packaging lid films designed for low adherence to the packaged products: these films have a sealant layer coated on the outermost surface with hydrophobic oxide nanoparticles. Again in order to facilitate extraction of fluids from packages, WO2020/025148A1 discloses packages made from multilayer thermoplastic films having hydrophobic coating on the surface of the film.
In other contexts, it may be desirable to achieve an effective and quick vacuumization of the package, minimizing the quantity of air remaining trapped inside the package. In this respect, U.S. Pat. No. 7,022,058 B2 discloses thermal/mechanically embossed films to create channels or a dimpled surface on a polymeric film such that, when the two panels of the bag/pouch collapse under vacuum pressure from the nozzle, the one embossed panel allows the air to be drawn towards the vacuum nozzle or vacuum source at the open end of the bag/pouch. This facilitates removal of the air from the bottom end of the bag and from around the food product or item being vacuum packaged. Although extensively used, the solution disclosed in U.S. Pat. No. 7,022,058 B2 presents several drawbacks: in fact embossing thin multilayer films requires temperature controlled calenders, with related purchase and operation costs. Moreover, embossing represents an additional operation in the manufacturing process of the film, which thus inevitably increases manufacturing costs and process complexity. Furthermore, embossing thin films may damage the film or alter the film properties.
The object of the present invention is to solve the drawbacks and/or limitations of the above prior art. A first object of the invention is to provide a multilayer film for packages, optionally for vacuum packages designed to confer to the package enhanced ability to be emptied from its content or vacuumized.
Furthermore, it is an object of the present invention to provide a multilayer film and a related package which can be manufactured without requiring additional expensive steps or specific tools compared to conventional films and packages.
A further object of the present invention is to provide a package guaranteeing a strong seal and a robust packaging.
Another object of the invention is a package of simple and cost-effective structure.
An additional object is that of offering a package suitable of improved aesthetics.
A yet further object is to provide a process for effectively making the mentioned film, package and related packaged product.
Finally, it is an object of the invention providing a multilayer film structure and a related manufacturing process, which may be implemented even in case of thin films such as those for packaging, with no risk of damaging the film or altering the film properties during manufacture.
These and other objects, which will become more apparent from the following description, are substantially achieved by a multilayer film and related manufacturing process, and by a package and a related packaging process according to one or more of the accompanying claims and/or the following aspects.
One or more of the above objects are substantially achieved by a packaging multilayer film and/or by a film manufacturing process according to any one of the corresponding aspects herewith enclosed. One or more of the above objects are also attained by a packaging article, a package and packaging processes according to one or more of the accompanying aspects.
Aspects of the invention are disclosed below.
A 1st aspect concerns a multilayer film for packaging, optionally for vacuum packaging, the multilayer film having a first external surface destined to contact a product hosted in a package and a second external surface opposite to the first external surface, wherein the multilayer film comprises:
In a 2nd aspect according to the 1st aspect one or more regions of said first external surface of the multilayer film present a Mean Roughness Depth (Rz) of at least 4.5 μm, measured according to ISO4287.
In a 3rd aspect according to any one of the preceding aspects the entire first external surface of the multilayer film has a Mean Roughness Depth (Rz) of at least 4.5 μm, measured according to ISO4287.
In a 4th aspect according to any one of the preceding aspects one or more regions of said first external surface of the multilayer film present a Mean Roughness Depth (Rz) of at least 5.0 μm, measured according to ISO4287; or
In a 5th aspect according to any one of the preceding aspects wherein the microparticles are spherical or spheroid or ovoid or teardrop shaped microparticles, or wherein the microparticles are non-hollow spherical or spheroid or ovoid or teardrop shaped microparticles.
In a 6th aspect according to any one of the preceding aspects the microparticles have an average particle diameter from 10 μm to 110 μm, optionally approximately from 20 μm to 100 μm, more optionally approximately from 30 μm to 90 μm.
In a 7th aspect according to any one of the preceding aspects the microparticles present a particle volume from 5.2·102 μm3 to 7.0·105 μm3, optionally approximately from 4.1·103 μm3 to 5.2·105 μm3, more optionally approximately from 1.4·104 μm3 to 3.8·105 μm3.
In an 8th aspect according to any one of the preceding aspects the microparticles are incorporated in the heat-sealable layer (A), each of said microparticles being entirely embedded in thermoplastic material forming the heat-sealable layer (A).
In a 9th aspect according to any one of the preceding aspects the microparticles are incorporated in the thermoplastic mono or multilayer base layer (B), each of said microparticles being entirely embedded in thermoplastic material forming the mono or multilayer base layer (B).
In a 10th aspect according to any one of the preceding aspects the microparticles in said heat-sealable layer (A) are in amount of at least 5% by weight calculated in respect of the total weight of said heat-sealable layer (A).
In an 11th aspect according to the preceding aspect the microparticles in the heat-sealable layer (A) are in amount which is:
In a 12th aspect according to any one of the preceding aspects the mono or multilayer base layer (B) comprises no microparticles or microparticles in amount lower than 1% by weight calculated in respect of the total weight of said mono or multilayer base layer (B).
In a 13th aspect according to any one of the preceding aspects from 1 to 11 the microparticles in the mono or multilayer base layer (B) are in amount of at least 5% by weight calculated in respect of the total weight of said mono or multilayer base layer (B).
In a 14th aspect according to the preceding aspect the microparticles in the mono or multilayer base layer (B) are in amount which is:
In a 15th aspect according to any one of the 12th or 13th or 14th aspect when depending upon any one of the preceding aspects from 1 to 9, wherein the heat-sealable layer (A) comprises no microparticles or microparticles in amount lower than 1% by weight calculated in respect of the total weight of said heat-sealable layer (A).
In a 16th aspect according to any one of the preceding aspects the heat-sealable layer (A) has a free and not further coated surface, opposed to the mono or multilayer base layer (B), defining said first external surface destined to contact the product.
In a 17th aspect according to any one of the preceding aspects the heat sealable layer (A) has an average thickness from 1 μm to 30 μm, optionally from 2 μm to 20 μm, and
In a 18th aspect according to any one of the preceding aspects the microparticles have a particle size, optionally an average particle diameter, of at least 20%, optionally at least 30%, more optionally at least 50%, greater than the average thickness of the layer of the film in which the microparticles are incorporated.
In a 19th aspect according to any one of the preceding aspects the heat sealable layer (A) has an average thickness smaller than 10 μm, optionally from 1 μm to 5 μm.
In a 20th aspect according to any one of the preceding aspects with the exception of the microparticles, the multilayer film consists of one or more thermoplastic materials, and
In a 21st aspect according to any one of the preceding aspects the heat-sealable layer (A) comprises a major amount of a polymer selected among ethylene-vinyl acetate copolymers (EVA), polyethylenes, homogeneous or heterogeneous linear ethylene-alpha-olefin copolymers, polypropylene copolymers (PP), ethylene-propylene copolymers (EPC), acrylates, methacrylates, ionomers, polyesters, polyamides and their blends.
In a 22nd aspect according to any one of the preceding aspects the base layer (B) is monolayer (b); or the base layer (B) is multilayer having a/the support layer (b) directly adhered to the heat-sealable layer (A), only said support layer incorporating the microparticles.
In a 23rd aspect according to any one of the preceding aspects the thermoplastic base layer (B) is monolayer and consists of a support layer (b), or is a multilayer (B) and comprises a support layer (b) directly adhered to the heat sealable layer (A).
In a sub aspect of this aspect said support layer (b) has a major proportion of, optionally consisting of, one or more thermoplastic resins selected from polyethylenes, polypropylenes, ethylene vinyl acetates (EVAs), ionomers, polyamides, polyesters, optionally blended with adhesive resins.
In a 24th aspect according to any one of the preceding aspects the base layer (B) is multilayer and comprises one or more inner layers selected among an inner gas barrier layer (8), an inner bulk layer, an inner tie layer and/or an outer anti-abuse layer.
In a 25th aspect according to any one of the preceding aspects the microparticles are at least one among acrylic microparticles, silica microparticles, boron silicate microparticles, calcium phosphate microparticles, calcium stearate microparticles, glass microparticles and charcoal powders.
In a 26th aspect according to any one of the preceding aspects the thermoplastic heat sealable layer (A) and at least a/the support layer (b) of the thermoplastic mono or multilayer base layer (B) directly adhered to layer (A) are obtained by a co-extrusion process, wherein the microparticles are embedded into one or both the support layer (b) of the thermoplastic base layer (B) and the heat sealable layer (A) during the co-extrusion process.
In a 27th aspect according to any one of the preceding aspects said second external surface is smooth or presents a Mean Roughness Depth (Rz) lower than 1.5 μm, measured according to ISO4287.
In a 28th aspect according to any one of the preceding aspects said one or more regions of said first external surface, optionally the entire first external surface, of the multilayer film are patterned surface regions comprising:
wherein the distance between crests of said micro-protrusions and the smooth base surface is comprised between 30 μm and 100 μm, optionally between 40 μm and 80 μm.
In a 29th aspect according to any one of the preceding aspects from 1 to 15 and from 17 to 28, wherein the surface of the heat-sealable layer (A) not directly adhered to the base layer (B) is coated with a hydrophobic or super-hydrophobic layer (C).
In a 30th aspect according to the preceding aspect the super-hydrophobic layer (C) is made from an inorganic composition comprising hydrophobic oxide nanoparticles having an average particle diameter from 3 nm to 100 nm.
A 31st aspect concerns a process of manufacturing the multilayer film according to any one of the preceding aspects comprising coextruding at least the thermoplastic heat-sealable layer (A) with the thermoplastic monolayer (B) or with at least the/a support layer (b) of the multilayer base layer (B) directly adhered to the heat-sealable layer (A).
In a 32nd aspect according to the preceding aspect the thermoplastic heat-sealable layer (A) is co-extruded with all layers of the multilayer base layer (B).
In a 33rd aspect according to the 31st or 32nd aspect the thermoplastic heat-sealable layer (A) is co-extruded with the thermoplastic monolayer (b) or with at least the support layer of the multilayer base layer (B) directly adhered to layer (A) using either a round or a flat die respectively shaping the polymer melt into a tubular or a flat film.
In a 34th aspect according to any one of the preceding aspects from 30 to 32 the microparticles are mixed with the thermoplastic polymer(s) used for extrusion of the monolayer (B) or of the support layer (b) of multilayer base layer (B) directly adhered to heat-sealable layer (A); and/or
In a 35th aspect according to the preceding aspect the microparticles are compounded with a carrier resin to give a masterbatch which is then extruded with thermoplastic polymer(s) used for the monolayer (b) or the support layer of multilayer base layer (B) directly adhered to layer (A), and/or the microparticles are compounded with a carrier resin to give a masterbatch which is then extruded with thermoplastic polymer(s) used for the heat-sealable layer (A).
In a 35bis aspect according to the 34th aspect the microparticles are dry blended with the respective thermoplastic polymer(s) forming the monolayer (B) or the support layer of multilayer base layer (B) directly adhered to layer (A) directly in extrusion, without previous compounding, and/or the microparticles are dry blended with the respective thermoplastic polymer(s) forming the heat-sealable layer (A) directly in extrusion, without previous compounding.
A 36th aspect concerns an article for packaging comprising at least one multilayer film of any one of aspects from 1 to 30 or obtained using the process of any one of aspects from 31 to 35, wherein the multilayer film is configured to define or cooperate to define a volume, in particular an inner volume, destined to receive at least one product,
In a 37th aspect according to the preceding aspect the article has at least one opening for introducing a product, optionally a food product, into the volume, optionally into one or more seats or spaces of the inner volume.
In a 38th aspect according to the 35th or 36th aspect the article is in a form selected among the following options:
In a 38th bis aspect according to the 38th aspect, the article for packaging is in the form of a pouch or a bag formed from or comprising the multilayer film, with said first external surface of the multilayer film directly facing the inner volume of the pouch or bag, said pouch or bag being equipped with a spout or an accommodation for inserting a straw.
A 39th aspect concerns a vacuum package comprising:
In a 40th aspect according to the preceding aspect the vacuum package comprises one or more seats or spaces, wherein the product is housed in each one of said one or more seats or spaces, wherein said one or more seats or spaces are vacuumized and hermetically sealed, optionally heat sealed, with said at least a portion of the first external surface of the multilayer film contacting the product.
In a 41st aspect according to the 38th or 39th aspect the package is a vacuum skin package, and wherein the multilayer film forms a skin on at least a portion of an external surface of the product, optionally on the entire product external surface.
In a 42nd aspect according to the 39th or 40th or 41st aspect the vacuum package is in the form of a bag or pouch entirely formed by a single multilayer film, wherein said first external surface of the multilayer film:
In a 43rd aspect according to the 39th or 40th or 41st aspect the vacuum package is in the form of a bag or pouch comprising or consisting of two or more films coupled together, optionally heat sealed together, to form said bag or pouch, wherein at least one of the two or more films is a multilayer film according to any one of the preceding aspects from 1 to 30 and wherein the first external surface of said at least one multilayer film:
In a 44th aspect according to the 42nd or 43rd aspect one or more spaces inside the pouch or bag contain a treatment gas different from air.
In a 45th aspect according to the 39th or 40th or 41st aspect the vacuum package comprises a tray, which is either a flat tray or a tray with a base wall and a side wall emerging from the base wall, wherein:
In a 46th aspect according to the 39th or 40th or 41st aspect the vacuum package comprises a tray, which is either a flat tray or a tray with a base wall and a side wall emerging from the base wall, wherein:
In a 47th aspect according to the 39th or 40th or 41st aspect the vacuum package comprises a tray, which is either a flat tray or a tray with a base wall and a side wall emerging from the base wall, wherein:
A 48th aspect concerns a packaging process comprising:
A 49th aspect concerns a packaging process comprising:
In a 50th aspect according to the 48th or 49th aspect during gas evacuation, the at least one multilayer film is draped down onto the product and forms a vacuum skin package.
In a 51st aspect according to any one of the preceding aspects from 48 to 50 sealing comprises:
In a 52nd aspect according to the preceding aspect wherein:
In a 53rd aspect according to the 51st or 52nd aspect once the gas evacuation step is complete and before sealing, in particular before heat sealing, a treatment gas is back-filled into the pouch or bag or tray package,
A 54th aspect concerns a packaging process comprising the following steps:
In a 54bis aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
A 55th aspect concerns a packaging process comprising the following steps:
In a 55bis aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
A 56th aspect concerns a packaging process comprising the following steps:
In a 56bis aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
In a 57th aspect according to the 54th or 55th or 56th aspect or according to aspect 54bis or 55bis or 56bis, the step of evacuating gas comprises:
In a 58th aspect according to any one of the preceding aspects 54 or 55 or 56 or 54bis or 55bis or 56bis or 57 once the gas evacuation step is complete and before sealing, in particular before heat sealing, a treatment gas is back-filled into said seat or space, through the same nozzle used for gas evacuation or through a distinct nozzle.
In a 59th aspect according to the preceding aspect the treatment gas does not contain oxygen such that residual oxygen level inside the seat or space is reduced upon back-filling.
In a 60th aspect according to the 57th or 58th or 59th aspect the at least one nozzle, or each one of the nozzle and the distinct nozzle, comprises a respective external nozzle surface and one or more suction/injection apertures defined at said external nozzle surface; and
In a 61st aspect according to any one of the preceding aspects from 57 to 60 the nozzle, or each one of the nozzle and the distinct nozzle, comprises a terminal large and thin portion having a thickness sensibly smaller than its width configured for insertion in a seat or space of flat packages.
A 62nd aspect concerns a packaging process comprising the following steps:
In a 62bis aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
A 63rd aspect concerns a packaging process comprising the following steps:
In a 63bis aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
A 64th aspect concerns a packaging process comprising the following steps:
In a 64bis aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
A 65th aspect concerns a packaging process comprising the following steps:
In a 65bis aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
A 66th concerns a packaging process comprising the following steps:
In a 67th aspect according to the preceding aspect, the packaging process is according to any one of the preceding aspects from 48 to 53.
A 68th aspect concerns a package comprising:
A 69th aspect concerns a packaging process comprising:
In the detailed description, in the figures and in the claims, corresponding parts are indicated by same reference numerals even if associated to different embodiments.
The figures may illustrate parts or components or assemblies, including aspects of the invention, by representations that are not in scale; furthermore, the figures may provide schematic representations of aspects of the invention.
Unless otherwise stated, all the percentages are percentages by weight.
Some embodiments and some aspects of the invention are described hereinafter with reference to the accompanying drawings, provided only for illustrative and, therefore, non-limiting purposes, in which:
The term product P means an article or a composite of articles of any kind. For example, the product may be of a foodstuff type and be in solid, liquid or gel form, i.e. in the form of two or more of the aforementioned aggregation states. In the food sector, the product may comprise: meat, fish, cheese, processed meat, fresh or frozen ready meals of various kinds.
The packaging apparatus/process and the apparatus process for making the multilayer film described herein may include at least one control unit designed to perform the steps of the process for making the package. The control unit may be only one or be formed by a plurality of different control units according to the design choices and the operational needs. The term control unit means an electronic component which can comprise at least one of: a digital processor (for example comprising at least one selected from the group of: CPU, GPU, GPGPU), a memory (or memories), an analog circuit, or a combination of one or more digital processing units with one or more analog circuits. The control unit may be “configured” or “programmed” to perform some steps: this can be done in practice by any means that allows configuring or programming the control unit. For example, in the case of a control unit comprising one or more CPUs and one or more memories, one or more programs can be stored in appropriate memory banks connected to the CPU or to the CPUs; the program or programs contain instructions which, when executed by the CPU or the CPUs, program or configure the control unit to perform the operations described in relation to the control unit. Alternatively, if the control unit is or includes analog circuitry, then the control unit circuit may be designed to include circuitry configured, in use, for processing electrical signals so as to perform the steps related to control unit. The control unit may comprise one or more digital units, for example of the microprocessor type, or one or more analog units, or a suitable combination of digital and analog units; the control unit can be configured for coordinating all the actions necessary for executing an instruction and instruction sets.
As used herein, the term “film” is inclusive of plastic web, regardless of whether it is film or sheet or tubing. The film of the invention is a multilayer film including two or more layers. Each film layer is made of one or more polymeric materials or one or more polymeric materials with the addition of microparticles which may be of a non-polymer material.
As used herein, the terms “inner layer” and “internal layer” refer to any film layer having both of its principal surfaces directly adhered to another layer of the film.
As used herein, the phrase “outer layer” or “external layer” refers to any film layer having only one of its principal surfaces directly adhered to another layer of the film.
As used herein, the phrases “seal layer”, “sealing layer”, “heat seal layer”, and “sealant layer”, refer to an outer layer involved in the sealing of the film to itself, in particular to the same outer seal layer or to the other outer layer of the same film, to another film, and/or to another article which is not a film.
As used herein, the phrases “outer anti-abuse layer”, “outer abuse-resistant layer” and “outer skin layer” refer to an outer layer of the film which, in the final package, is directed towards the environment and not towards the packaged product.
As used herein, the words “tie layer” or “adhesive layer” refer to any inner film layer having the primary purpose of adhering two layers to each other.
As used herein, the phrases “longitudinal direction” and “machine direction”, herein abbreviated “LD” and “MD”, refer to a direction “along the length” of the film, i.e., the direction of the film as the film is formed during coextrusion.
As used herein, the phrase “transverse direction” or “crosswise direction”, herein abbreviated “TD”, refers to a direction across the film, perpendicular to the machine or longitudinal direction.
As used herein, the term “extrusion” is used with reference to the process of forming continuous shapes by forcing a molten plastic material through a die, followed by cooling (quenching) or chemical hardening. Immediately prior to extrusion through the die, the relatively high-viscosity polymeric material may be fed into a rotating screw of variable pitch, i.e., an extruder, which forces the polymeric material through the die.
As used herein, the term “coextrusion” refers to the process of extruding two or more materials through a single die with two or more orifices arranged so that the extrudates merge and weld together into a laminar structure before chilling, i.e., quenching. The term “coextrusion” as used herein also includes “extrusion coating”.
As used herein, the term “extrusion coating” refers to processes by which a “coating” of molten polymer(s), comprising one or more layers, is extruded onto a solid “substrate” in order to coat the substrate with the molten polymer coating to bond the substrate and the coating together, thus obtaining a complete film.
As used herein the terms “coextrusion”, “coextruded”, “extrusion coating”, “extrusion coated” and the like are referred to processes and multilayer films which are not obtained by sole lamination, namely by gluing or welding together pre-formed webs.
As used herein, “vacuum deposition” refers to a process that allows depositing a material molecule-by-molecule or by groups of molecules forming a molecular chain on a solid surface, e.g. a film, to form a layer of this material. The material to be deposited may be a formulated monomer or oligomer in the form of a liquid or a solid. Upon application of vacuum and heat, the material evaporates and then deposits on the film surface. Upon deposition, the material returns to its original state which may be liquid, solid or even gel, if the material is formulated using both a liquid and a solid. As upon heating under vacuum the liquid or solid materials are converted into a vapor, this “vacuum deposition” process is also referred to as vacuum “vapor deposition” process.
As used herein, the terms “outer anti-abuse surface” or “outer abuse-resistant surface” of a part of a film, of a film or of a package made therefrom mean the outermost surface that, in the final package, is directed towards the environment and not towards the product.
As used herein, the terms “rough surface” or “roughened surface” refer to a surface of a film having a non-smooth pattern, i.e. a surface presenting irregular structures such as, e.g., holes, pillars, spikes, wrinkles, scratches, bumps, indentations etc., wherein such structures are engraved in, or protrude from, the surface.
The term “contact angle θ” relates to the angle made by a droplet of liquid on a surface of a solid substrate and it is used as a quantitative measure of the wettability of the surface. If the liquid spreads completely across the surface and forms a film, the contact angle θ is 0°. For water, a surface or a coating is usually considered hydrophobic if the contact angle θ is greater than 90°. Surfaces or coatings with water contact angles greater than 130° are also referred to as “super-hydrophobic”.
As used herein, the term “super-hydrophobic” refers to the property of a surface to repel water very effectively. This property is expressed by a water contact angle θ exceeding 130°.
As used herein, the term “super-hydrophobic coating composition” refers to a composition that, when applied onto a surface of a thermoplastic film, may form a super-hydrophobic coating.
As used herein, the term “super-hydrophobic coating” relates to a coating characterized by a water contact angle θ higher than 130°, said contact angle θ being measured according to ASTM D7490-13.
As used herein, the term “hydrophobic” refers to the property of a surface to repel water with a water contact angle θ from about 90° to about 130.
As used herein, the term “hydrophobic coating composition” refers to a hydrophobic coating composition comprising components that have the ability to form a hydrophobic coating, upon curing and/or drying.
As used herein, the term “major amount” or “major proportion” refer to an amount of a component higher than 50% by weight in respect of the total amount by weight of the components of a referred element (e.g. a film, a layer etc.).
As used herein, the term “minor amount” or “minor proportion” refer to an amount of a component lower than 50% by weight in respect of the total amount by weight of the components of a referred element (e.g. a film, a layer etc.).
As used herein, the term “polymer” refers to the product of a polymerization reaction, and is inclusive of homo-polymers, and co-polymers.
As used herein, the term “homo-polymer” is used with reference to a polymer resulting from the polymerization of a single type of monomer, i.e., a polymer consisting essentially of a single type of mer, i.e., repeating unit.
As used herein, the term “co-polymer” refers to polymers formed by the polymerization reaction of at least two different types of monomers. For example, the term “co-polymer” includes the co-polymerization reaction product of ethylene and an alpha-olefin, such as 1-hexene. When used in generic terms the term “co-polymer” is also inclusive of, for example, ter-polymers. The term “co-polymer” is also inclusive of random co-polymers, block co-polymers, and graft co-polymers.
As used herein, the term “polymer” is inclusive of heterogeneous polymers and homogeneous polymers.
As used herein, the phrase “heterogeneous polymer” or “polymer obtained by heterogeneous catalysis” refers to polymerization reaction products of relatively wide variation in molecular weight and relatively wide variation in composition distribution, i.e., typical polymers prepared, for example, using conventional Ziegler-Natta catalysts, for example, metal halides activated by an organometallic catalyst, i.e., titanium chloride, optionally containing magnesium chloride, complexed to trialkyl aluminum and may be found in patents such as U.S. Pat. No. 4,302,565 to Goeke et al. and U.S. Pat. No. 4,302,566 to Karol, et al. Heterogeneous catalyzed copolymers of ethylene and an alpha-olefin may include linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE) and ultra-low-density polyethylene (ULDPE). Some copolymers of this type are available from, for example, The Dow Chemical Company, of Midland, Michigan., U.S.A. and sold under the trademark DOWLEX resins.
As used herein, the phrase “homogeneous polymer” or “polymer obtained by homogeneous catalysis” refers to polymerization reaction products of relatively narrow molecular weight distribution and relatively narrow composition distribution. Homogeneous polymers are structurally different from heterogeneous polymers, in that homogeneous polymers exhibit a relatively even sequencing of co-monomers within a chain, a mirroring of sequence distribution in all chains, and a similarity of length of all chains, i.e., a narrower molecular weight distribution. This term includes those homogeneous polymers prepared using metallocenes, or other single-site type catalysts, as well as those homogenous polymers that are obtained using Ziegler Natta catalysts in homogenous catalysis conditions.
The co-polymerization of ethylene and alpha-olefins under homogeneous catalysis, for example, co-polymerization with metallocene catalysis systems which include constrained geometry catalysts, i.e., monocyclopentadienyl transition-metal complexes is described in U.S. Pat. No. 5,026,798 to Canich. Homogeneous ethylene/alpha-olefin copolymers (E/AO) may include modified or unmodified ethylene/alpha-olefin copolymers having a long-chain branched (8-20 pendant carbons atoms) alpha-olefin comonomer available from The Dow Chemical Company, known as AFFINITY and ATTANE resins, TAFMER linear copolymers obtainable from the Mitsui Petrochemical Corporation of Tokyo, Japan, and modified or unmodified ethylene/alpha-olefin copolymers having a short-chain branched (3-6 pendant carbons atoms) alpha-olefin comonomer known as EXACT resins obtainable from ExxonMobil Chemical Company of Houston, Texas, U.S.A.
As used herein, the term “polyolefin” refers to any polymerized olefin, which can be linear, branched, cyclic, aliphatic, aromatic, substituted, or unsubstituted. More specifically, included in the term polyolefin are homo-polymers of olefin, co-polymers of olefin, co-polymers of an olefin and a non-olefinic co-monomer co-polymerizable with the olefin, such as vinyl monomers, modified polymers thereof, and the like. Specific examples include polyethylene homo-polymer, polypropylene homo-polymer, polybutene homo-polymer, ethylene-alpha-olefin which are copolymers of ethylene with one or more-alpha-olefins such as butene-1, hexene-1, octene-1, or the like as a comonomer, and the like, propylene-alpha-olefin co-polymer, butene-alpha-olefin co-polymer, ethylene-unsaturated ester co-polymer, ethylene-unsaturated acid co-polymer, (e.g. ethylene-ethyl acrylate co-polymer, ethylene-butyl acrylate co-polymer, ethylene-methyl acrylate co-polymer, ethylene-acrylic acid co-polymer, and ethylene-methacrylic acid co-polymer), ethylene-vinyl acetate copolymer, ionomer resin, polymethylpentene, etc.
As used herein, the term “Cyclo olefin copolymers (COC)” refers to amorphous, transparent thermoplastics produced by copolymerization of cycloolefins such as norbornene or cyclopentadiene with ethylene using a metallocene catalyst.
As used herein the term “ionomer” refers to the products of polymerization of ethylene with an unsaturated organic acid, and optionally also with an unsaturated organic acid (C1-C4)-alkyl ester, partially neutralized with a mono- or divalent metal ion, such as lithium, sodium, potassium, calcium, magnesium and zinc. Typical unsaturated organic acids are acrylic acid and methacrylic acid, which are thermally stable and commercially available. Unsaturated organic acid (C1-C4)-alkyl esters are typically (meth)acrylate esters, e.g. methyl acrylate and isobutyl acrylate. Mixtures of more than one unsaturated organic acid comonomer and/or more than one unsaturated organic acid (C1-C4)-alkyl ester monomer can also be used in the preparation of the ionomer.
As used herein, the phrase “modified polymer”, as well as more specific phrases such as “modified ethylene/vinyl acetate copolymer”, and “modified polyolefin” refer to such polymers having an anhydride functionality, grafted thereon and/or copolymerized therewith and/or blended therewith. Preferably, such modified polymers have the anhydride functionality grafted on or polymerized therewith, as opposed to merely blended therewith. As used herein, the term “modified” refers to a chemical derivative, e.g. one having any form of anhydride functionality, such as anhydride of maleic acid, crotonic acid, citraconic acid, itaconic acid, fumaric acid, etc., whether grafted onto a polymer, copolymerized with a polymer, or blended with one or more polymers, and is also inclusive of derivatives of such functionalities, such as acids, esters, and metal salts derived therefrom.
As used herein, the phrase “anhydride-containing polymer” and “anhydride-modified polymer” refer to one or more of the following: (1) polymers obtained by copolymerizing an anhydride-containing monomer with a second, different monomer, and (2) anhydride grafted copolymers, and (3) a mixture of a polymer and an anhydride-containing compound.
As used herein, the phrase “ethylene-alpha-olefin copolymer” refers to heterogeneous and to homogeneous polymers such as linear low density polyethylene (LLDPE) with a density usually in the range of from about 0.900 g/cc to about 0.930 g/cc, linear medium density polyethylene (LMDPE) with a density usually in the range of from about 0.930 g/cc to about 0.945 g/cc, and very low and ultra-low density polyethylene (VLDPE and ULDPE) with a density lower than about 0.915 g/cc, typically in the range 0.868 to 0.915 g/cc, and such as metallocene-catalyzed EXACT™ and EXCEED™ homogeneous resins obtainable from Exxon, single-site AFFINITY™ resins obtainable from Dow, and TAFMER™ homogeneous ethylene-alpha-olefin copolymer resins obtainable from Mitsui. All these materials generally include co-polymers of ethylene with one or more co-monomers selected from (C4-C10)-alpha-olefin such as butene-1, hexene-1, octene-1, etc., in which the molecules of the copolymers comprise long chains with relatively few side chain branches or cross-linked structures.
As used herein, the term “EVA” refers to ethylene and vinyl acetate copolymers. The vinylacetate monomer unit can be represented by the general formula: [CH3COOCH═CH2].
As used herein, the phrase “acrylates or acrylate-based resin” refers to homopolymers, copolymers, including e.g. bipolymers, terpolymers, etc., having an acrylate moiety in at least one of the repeating units forming the backbone of the polymer. In general, acrylate-based resins are also known as polyalkyl acrylates. Acrylate resins or polyalkyl acrylates may be prepared by any method known to those persons skill in the art. Suitable examples of these resins for use in the present invention include ethylene/methacrylate copolymers (EMA), ethylene/butyl acrylate copolymers (EBA), ethylene/methacrylic acid (EMAA), ethylene/methyl methacrylate (EMMA), optionally modified with carboxylic or preferably anhydride functionalities, ionomers and the like. Such as LOTRYL 18 MA 002 by Arkema (EMA), Elvaloy AC 3117 by Du Pont (EBA), Nucrel 1202HC by Du Pont (EMAA), Surlyn 1061 by Du Pont (Ionomer).
As used herein the term “polyamide” refers to high molecular weight polymers having amide linkages along the molecular chain, and refers more specifically to synthetic polyamides such as nylons. Such term encompasses both homo-polyamides and co-(or ter-) polyamides. It also specifically includes aliphatic homo-polyamides or co-polyamides, aromatic homo-polyamides or co-polyamides, and partially aromatic homo-polyamides or co-polyamides, modifications thereof and blends thereof. The homo-polyamides are derived from the polymerization of a single type of monomer comprising both the chemical functions, which are typical of polyamides, i.e. amino and acid groups, such monomers being typically lactams or aminoacids, or from the polycondensation of two types of polyfunctional monomers, i.e. polyamines with polybasic acids. The co-, ter-, and multi-polyamides are derived from the copolymerization of precursor monomers of at least two (three or more) different polyamides. As an example in the preparation of the co-polyamides, two different lactams may be employed, or two types of polyamines and polyacids, or a lactam on one side and a polyamine and a polyacid on the other side. Exemplary polymers are polyamide 6, polyamide 6/9, polyamide 6/10, polyamide 6/12, polyamide 11, polyamide 12, polyamide 6/12, polyamide 6/66, polyamide 66/6/10, modifications thereof and blends thereof. Said term also includes crystalline or partially crystalline, aromatic or partially aromatic polyamides.
As used herein, the phrase “amorphous polyamide” refers to polyamides or nylons with an absence of a regular three-dimensional arrangement of molecules or subunits of molecules extending over distances, which are large relative to atomic dimensions. However, regularity of structure exists on a local scale. See, “Amorphous Polymers,” in Encyclopedia of Polymer Science and Engineering, 2nd Ed., pp. 789-842 (J. Wiley & Sons, Inc. 1985). This document has a Library of Congress Catalogue Card Number of 84-19713. In particular, the term “amorphous polyamide” refers to a material recognized by one skilled in the art of differential scanning calorimetry (DSC) as having no measurable melting point (less than 0.5 cal/g) or no heat of fusion as measured by DSC using ASTM 3417-83. Such nylons include those amorphous nylons prepared from condensation polymerization reactions of diamines with dicarboxylic acids. For example, an aliphatic diamine is combined with an aromatic dicarboxylic acid, or an aromatic diamine is combined with an aliphatic dicarboxylic acid to give suitable amorphous nylons.
As used herein, the term “polyester” refers to homopolymers or copolymers (also known as “copolyesters”) having an ester linkage between monomer units which may be formed, for example, by condensation polymerization reactions of lactones or by polymerization of dicarboxylic acid(s) and glycol(s). With the term “(co) polyesters” both homo and copolymers are intended.
As used herein, the term “aromatic polyester” refers to homopolymers or copolymers (also known as “copolyesters”) having an ester linkage between one or more aromatic or alkylsubstituted aromatic dicarboxylc acids and one or more glycols.
As used herein, the term “adhered” is inclusive of films which are directly adhered to one another using a heat-seal or other means, as well as films which are adhered to one another using an adhesive which is between the two films.
As used herein, the phrase “directly adhered”, as applied to layers, is defined as adhesion of the subject layer to the object layer, without a tie layer, adhesive, or other layer therebetween.
In contrast, as used herein, the word “between”, as applied to a layer expressed as being between two other specified layers, includes both direct adherence of the subject layer to the two other layers it is between, as well as a lack of direct adherence to either or both of the two other layers the subject layer is between, i.e., one or more additional layers can be imposed between the subject layer and one or more of the layers the subject layer is between.
As used herein the term “gas-barrier” when referred to a layer, to a resin contained in said layer, or to an overall structure, refers to the property of the layer, resin or structure, to limit to a certain extent passage through itself of gases.
When referred to a layer or to an overall structure, the term “gas-barrier” is used herein to identify layers or structures characterized by an Oxygen Transmission Rate (evaluated at 23° C. and 0% R.H. according to ASTM D-3985) of less than 500 cc/m2·day·atm, optionally lower than 100 cc/m2·day·atm, even more optionally lower than 50 cc/m2·day·atm.
As used herein, the phrase “flexible container” is inclusive of bags and pouches, in particular of end-seal, side-seal, L-seal, U-seal bags and pouches, stand-up pouches, back-seamed tubings and seamless tubings.
As used herein, the term “tray” refers to a support which may be flat or may include a base, a side wall emerging from the base wall perimeter, and optionally a top flange radially emerging from the top part of the side wall. The tray may be made in polymer material or it may be formed using the multilayer film of the invention and thus include non-polymer microparticles. The tray may comprise a paper or paperboard layer and/or a layer in non-polymer material.
As used herein, the term “package” is inclusive of packages made from or comprising the multilayer film of the invention such as flexible containers, or packages using one or more trays coupled with one or more films.
As used herein the term “average particle diameter” refers to the average diameter measured with a scanning electron microscope (FE-SEM), which can also be used in combination with another electron microscope such as a transmission electron microscope if the resolution of the scanning electron microscope is too low. Specifically, taking the particle diameter when the particles are spherical and the average of the longest dimension and shortest dimension as the diameter when they are non-spherical, the average particle diameter is the average of the diameters of 20 randomly-selected particles observed by scanning electron microscopy or the like.
As used herein the term “micro-particles” refers to particles having an average particle diameter from 0.5 to 100 microns.
A first embodiment of a multilayer film 1 according to aspects the invention is shown in
The multilayer packaging film 1 comprises:
In the embodiment of
In greater detail, the base layer B of film 1 of
As it may be seen from
In the embodiment of
In an aspect, one or more regions of the first external surface 2 of the multilayer film 1 of
From a structural point of view, the microparticles 6 of the film 1 of
The microparticles 6 used in the embodiment of
In the first embodiment of
Higher amounts of microparticles may be desirable: for example, the microparticles in the heat-sealable layer A may be present in amount which is:
A minor quantity of microparticles in the base layer B is not excluded in principle, such as microparticles in amount lower than 10% by weight, lower than 5% by weight, lower than 1% by weight calculated in respect of the total weight of said mono or multilayer base layer B. As the contribute to the Mean Roughness Depth (Rz) of the first external surface 2 is mostly given by microparticles present in the heat sealable layer A, layer A comprises a major proportion of the total amount of microparticles present in the whole film 1, optionally an amount of more than 60 wt %, more than 70 wt %, more than 80 wt %, more than 90 wt %, more than 95 wt %, more than 99 wt % of the total amount of microparticles present in the whole film 1. Optionally, layer A comprises the totality of the microparticles, i.e. layer B does not comprise microparticles.
Possible materials for the microparticles are indicated in below dedicated section MATERIALS FOR THE MICROPARTICLES.
Moving now to a more detailed description of the thickness of each layer and of the relative size of the microparticles, it is noted that the heat sealable layer A has an average thickness from 1 to 30 μm, optionally from 2 to 20 μm; the monolayer base layer B consists of support layer b directly adhered to the heat sealable layer A and having average thickness from 15 to 80 μm, optionally from 20 to 70 μm.
As to the microparticles 6, they have a particle size or average particle diameter of at least 20%, optionally at least 30%, more optionally at least 50%, greater than the average thickness of the heat-sealable layer A in which the microparticles are incorporated.
In term of materials, it is noted that the heat sealable layer A and the base layer B of the multilayer film 1, with the exception of the microparticles, are formed from one or more thermoplastic materials. Details of the materials for each one of the layers A and B are reported in below dedicated sections (MATERIALS FOR HEAT SEALABLE LAYER A, MATERIALS FOR BASE LAYER B).
In a currently preferred version of the film of
As it is visible from
Finally, it is noted that in the multilayer film 1 of
The variant of
In accordance with an aspect, layer C is a super-hydrophobic layer made from an inorganic composition comprising hydrophobic oxide nanoparticles having an average particle diameter from 3 to 100 nm.
The super-hydrophobic layer C has an average thickness from 0.1 to 5.0 microns, optionally from 0.2 to 4 microns, more optionally from 1.0 to 2.5 microns.
The hydrophobic oxide nanoparticles of the super-hydrophobic layer C have an average particle diameter of 3 to 100 nm, preferably 5 to 50 nm, more preferably 5 to 20 nm.
The average particle diameter can be measured with a scanning electron microscope (FE-SEM), possibly in combination with an electron microscope such as a transmission electron microscope. The specific surface area (BET method) of the hydrophobic oxide nanoparticles is not particularly limited, but is normally 50 to 300 m2/g, optionally 100 to 300 m2/g, measured according to ISO 9277. The amount of the hydrophobic oxide nanoparticles deposited onto the outer surface of the heat-sealable layer A (grammage after drying) is from 0.01 to 10 g/m2, optionally from 0.1 to 2.0 g/m2, more optionally from 0.2 to 1.5 g/m2.
The super-hydrophobic layer coating C confers to the first external surface 2 of the film 1 super-hydrophobic properties. For example, the first external surface 2 may be characterized by a water contact angle θ higher than 130°, optionally higher than 140°, more optionally higher than 150°, even more optionally higher than 160° measured according to ASTM D7490-13.
The super-hydrophobic layer coating C is a single layer coating but a multilayer coating is also possible. Possible materials for layers C are reported in below dedicated section (MATERIALS FOR SUPER-HYDROPHOBIC LAYER C).
A second embodiment of a multilayer film 1 according to aspects of the invention is shown in
The multilayer film 1 has a first external surface 2 and a second external surface 3 opposite to the first external surface 2. In practice, the first external surface 2 is destined to form an inner surface of a package, for example of a vacuum package, obtainable with the multilayer film 1: in other words, the first external surface 2 of the multilayer film 1 is destined to contact a product hosted in the vacuum package obtainable with film 1, while the second external surface 3 is destined to define part or the entirety of the outer anti-abuse surface of the package.
The multilayer packaging film 1 comprises:
In the embodiment of
Different from
Optionally, micro-particles may be present in the inner film layer(s) although in a currently preferred solution no microparticles are incorporated into the barrier layer 8 to avoid damages to its gas barrier properties. As described in regard to the film of
The variant of
A third embodiment of a multilayer film 1 according to aspects the invention is shown in
The multilayer film 1 has a first external surface 2 and a second external surface 3 opposite to the first external surface 2. In practice, the first external surface 2 is destined to form an inner surface of a package, for example of a vacuum package, obtainable with the multilayer film 1: in other words, the first external surface 2 of the multilayer film 1 is destined to contact a product hosted in the vacuum package obtainable with film 1, while the second external surface 3 is destined to define part or the entirety of the outer anti-abuse surface of the package.
The multilayer packaging film 1 comprises:
In the embodiment of
In greater detail, the base layer B of film 1 has one of its principal surfaces defining the second external surface 3, while the other of the principal surfaces (indicated with reference numeral 4) of the base layer B is directly adhered to one of the principal surfaces (indicated with reference numeral 5) of the heat-sealable layer A. On its turn, heat-sealable layer A has the other principal surface defining the first external surface 2 of the film 1.
As it may be seen from
In the embodiment of
In an aspect, one or more regions of the first external surface 2 of the multilayer film 1 of
From a structural point of view, the microparticles 6 of the film 1 of
The microparticles 6 used in the embodiment of
In the third embodiment of
Higher amounts of microparticles may be desirable: for example the microparticles in the base layer B may in amount which is:
Although presence of microparticles also in layer A is not excluded, in this example layer B of the embodiments of
Possible materials for the microparticles are indicated in below dedicated section MATERIALS FOR THE MICROPARTICLES.
In the example of
As to the microparticles 6, they have a particle size or average particle diameter of at least 20%, optionally at least 30%, more optionally at least 50%, greater than the average thickness of the mono base layer B in which the microparticles are incorporated.
In term of materials, it is noted that the heat sealable layer A and the base layer B of the multilayer film 1, with the exception of the microparticles, are formed from one or more thermoplastic materials. Details of the materials for each one of the layers A and B are reported in below dedicated sections (MATERIALS FOR HEAT SEALABLE LAYER A, MATERIALS FOR BASE LAYER B).
In a currently preferred version of the film of
Mean Roughness Depth (Rz) greater than 5 μm, while the second external surface 3 of film 1 is smooth or presents a Mean Roughness Depth (Rz) less than 1.5 μm (Rz being measured according to ISO4287).
In a way similar to what disclosed in
Finally, it is noted that in the multilayer film 1 of
The variant of
A fourth embodiment of a multilayer film 1 according to aspects the invention is shown in
The multilayer film 1 has a first external surface 2 and a second external surface 3 opposite to the first external surface 2. In practice, the first external surface 2 is destined to form an inner surface of a package, for example of a vacuum package, obtainable with the multilayer film 1: in other words, the first external surface 2 of the multilayer film 1 is destined to contact a product hosted in the vacuum package obtainable with film 1, while the second external surface 3 is destined to define part or the entirety of the outer anti-abuse surface of the package.
The multilayer packaging film 1 comprises:
In the embodiment of
Different from
Optionally, micro-particles may be present in said other inner film layers (in addition to those present in support layer b) although in a currently preferred solution no microparticles are incorporated into the barrier layer 8 to avoid damages to its gas barrier properties.
The support layer b which is directly adhered to layer A comprises a major proportion of the total amount of microparticles present in the whole film 1, optionally an amount of more than 60 wt %, more than 70 wt %, more than 80 wt %, more than 90 wt %, more than 95 wt %, more than 99 wt % of the total amount of microparticles present in the whole film 1. Optionally support layer b comprises the totality of the microparticles, i.e. layer A does not comprise microparticles.
The variant of
The multilayer film 1 of the above embodiments of
In accordance with an aspect, the heat-sealable layer A of the films 1 in accordance with the embodiments described above may comprise a major amount of a polymer selected among ethylene-vinyl acetate copolymers (EVA), polyethylenes, homogeneous or heterogeneous, linear ethylene-alpha-olefin copolymers, polypropylene copolymers (PP), ethylene-propylene copolymers (EPC), acrylates and methacrylates, ionomers, polyesters, polyamides and their blends.
In a further aspect, the heat-sealable layer A comprises more than 60%, 70%, 80%, 90%, or 95% by weight, with respect to the weight of the same layer, of one or more of said polymers; optionally the heat sealable layer A substantially consists, of one or more of said polymers.
EVA is a copolymer formed from ethylene and vinyl acetate monomers wherein the ethylene units are present in a major amount and the vinyl-acetate units are present in a minor amount. The typical amount of vinyl-acetate may range from about 5 to about 20%.
Preferred polymers for the heat-sealable layer A are heterogeneous materials as linear low density polyethylene (LLDPE) with a density usually in the range of from about 0.910 g/cc to about 0.930 g/cc, linear medium density polyethylene (LMDPE) with a density usually in the range of from about 0.930 g/cc to about 0.945 g/cc, and very low and ultra-low density polyethylene (VLDPE and ULDPE) with a density lower than about 0.915 g/cc; and homogeneous polymers such as metallocene-catalyzed EXACT™ and EXCEED™ homogeneous resins obtainable from Exxon, single-site AFFINITY™ resins obtainable from Dow, QUEO by Borealis, TAFMER™ homogeneous ethylene-alpha-olefin copolymer resins obtainable from Mitsui. All these materials generally include co-polymers of ethylene with one or more co-monomers selected from (C4-C10)-alpha-olefin such as butene-1, hexene-1, octene-1, etc., in which the molecules of the copolymers comprise long chains with relatively few side chain branches or cross-linked structures.
These polymers can be advantageously blended in various percentages to tailor the sealing properties of the films depending on their use in packaging, as well known by those skilled in the art.
In a currently preferred embodiment, the heat-sealable layer A consists of blends of LLDPE and metallocene-PE resins.
Optionally, the resins for the heat-sealable layer A have a seal initiation temperature lower than 110° C., more optionally lower than 105° C., and yet more optionally lower than 100° C.
In the embodiment of
For example, in the first embodiment of the film 1 the monolayer base layer B comprises a major proportion of, optionally consists of, one or more thermoplastic resins selected from polyethylenes, polypropylenes, ethylene vinyl acetates (EVAs), ionomers, polyamides, polyesters, optionally blended with adhesive resins, such as anhydride-modified polyolefins, in order to improve the adhesion to the heat-sealable layer.
When the base layer B is multilayer, the support layer b directly adhered to layer A may be the same as monolayer base layer B and will not be further described to avoid repetitions.
The multilayer base layer B may comprise an inner gas barrier layer.
In an embodiment, the inner gas barrier layer may comprise a major proportion of, optionally may consist of, one or more polymers selected among ethylene/vinyl alcohol copolymers (EVOH), polyester homopolymers and copolymers, polyamide homopolymers and copolymers, polyvinyl alcohol copolymers (PV/A), polyvinyl chlorides (PVC), polyvinylidene chloride (co) polymers (PVDC) and their blends.
With polyvinylidene chloride (co) polymers, homopolymers of vinylidene chloride or its copolymers with other suitable monomers in minor amount are meant, such as vinylidene chloride/methyl acrylate copolymers (PVDC/MA), vinylidene chloride-vinyl chloride copolymers (PVDC/VC), vinylidene chloride-acrylonitrile copolymers and vinylidene chloride-methyl acrylate-vinyl chloride terpolymers. Especially preferred copolymers are vinylidene chloride/methyl acrylate copolymers (PVDC/MA). In an embodiment, the inner barrier layer may comprise a major proportion, optionally at least 70%, at least 80%, at least 90%, at least 95% by weight, or may consist of EVOH, optionally in admixture with one or more of the above polymers, more optionally in admixture with polyamides.
In another embodiment, the inner barrier layer may comprise a major proportion, optionally at least 70%, at least 80%, at least 90%, at least 95% by weight, or may consist of polyamides, optionally in admixture with one or more of the above polymers, more optionally in admixture with EVOH or polyesters.
In another embodiment, the inner barrier layer may comprise a major proportion, optionally at least 70%, at least 80%, at least 90%, at least 95% by weight, or may consist of one or more polyester(s), for example polyethylene terephtalate (PET), optionally in admixture with one or more of the above polymers.
In an option, the films comprise only one internal gas barrier layer, but multiple gas barrier layers may also be present.
The multilayer base layer B may comprise an outer, anti-abuse (or “skin”) layer.
The polymer(s) for the outer anti-abuse layer is generally selected based on its heat resistance during the sealing step. In fact, it may be advantageous that the polymer of this layer has a melting point higher than the melting point of the polymer of the heat-sealable layer A.
The outer anti-abuse layer may comprise a major proportion of, optionally may consist of, a polymer selected among polyolefins, ethylene-vinyl acetate copolymers, ionomers, (meth)acrylates copolymers, polyamides, polyesters and their blends.
Optionally, the surface of the outer anti-abuse layer not adhered to an inner layer may be superficially treated and/or coated in order to modify its surface properties. As an example, such surface may be corona-treated to improve surface printing.
The multilayer base layer B may comprise one or more inner tie layers. Tie layers have the main function of improving adhesion between the layers.
The tie layers may comprise a major proportion of, optionally may consist of, one or more adhesive polymers selected among polyolefins and modified polyolefins.
Specific, not limitative, examples of adhesive polymers include ethylene-vinyl acetate copolymers, ethylene-(meth)acrylate copolymers, ethylene-alpha-olefin copolymers, any of the above modified with carboxylic or anhydride functionalities, elastomers, and blends thereof. The tie layers may have a typical thickness from 2 to 15 microns, preferably from 3 to 10 microns.
The multilayer base layer B may comprise one or more inner bulk layers. The bulk layers may comprise a major proportion of, optionally may consists of, one or more polymers selected among EVA, acrylate based resins, ionomers, polyolefins, modified polyolefins and their admixtures.
Preferably, the overall thickness of the one or more bulk layers (H) is lower than 60%, optionally lower than 40% and/or higher than 10%, more optionally higher than 20% with respect to the total film thickness.
The layers of the present film may contain one or more additives typically included in such polymer compositions.
These additives include slip and anti-block agents such as talc, waxes, silica, and the like, antioxidants, stabilizers, plasticizers, fillers, pigments and dyes, cross-linking inhibitors, cross-linking enhancers, UV absorbers, odour absorbers, oxygen scavengers, antistatic agents, anti-fog agents or compositions, and the like. All these additives are well known and may be present in one or more layers of the film in appropriate amounts, known to those skilled in the art of packaging films.
The coating layer C may be a super-hydrophobic layer which comprises one or more organic or inorganic hydrophobic components selected among fluoropolymers, polysiloxanes, hydrophobic nanoparticles, for example hydrophobic oxide nanoparticles such as silica and silica precursors as tetraethyl orthosilicate (TEOS) and the like, or super-hydrophobic waxes.
In an example, the coating layer C may include hydrophobic oxide nanoparticles, more optionally hydrophobic oxide nanoparticles selected among silica (silicon dioxide), alumina, magnesium oxide, titania and their admixtures.
In a currently preferred solution coating C is an inorganic coating, namely a coating comprising major amount of inorganic elements and not including major amount of organic compounds, oligomers, cross-linked or cured polymers, organic networks and the like. For example, the coating C may not comprise organic compounds, oligomers, cross-linked or cured polymers or organic networks.
The hydrophobic oxide nanoparticles are not especially limited as long as they have hydrophobic properties. Accordingly, they may be particles made hydrophobic by suitable surface treatments, such as reactions with silane coupling agents.
Examples of suitable oxides are silica (silicon dioxide), alumina, magnesium oxide, titania or the like, and their admixtures.
Examples of silica include the products Aerosil R972, Aerosil R972V, Aerosil R972CF, Aerosil R974, Aerosil RX200 and Aerosil RY200 (Japan Aerosil) and Aerosil R202, Aerosil R805, Aerosil R812 and Aerosil R812S (Evonik Degussa). Examples of titania include the product Aeroxide TiO2 T805 (Evonik Degussa) and the like.
Examples of alumina include fine particles such as Aeroxide Alu C (Evonik Degussa) made hydrophobic by surface treatment with a silane coupling agent.
In a currently preferred option, the hydrophobic oxide is silica, as such or as silica precursor, for instance tetraethyl orthosilicate (TEOS) and the like.
In a currently preferred option, highly hydrophobic silica particles having surface trimethylsilyl groups are used.
The coating layer C may additionally comprise other inorganic elements such as zinc and/or magnesium.
The microparticles 6 described in the above embodiments may be made in any suitable sufficiently rigid material and configured in any suitable shape such as to be resistant to extrusion. In an option, the microparticles are solid (i.e. not hollow or porous) microparticles, as they are more resistant to the extrusion conditions and provide a better surface roughness.
The microparticles may comprise an organic component and/or an inorganic component. The organic component may be selected, for instance, among acrylic resin, urethane resin, melamine resin, amino resin, epoxy resin, polyethylene resin, pol-ystyrene resin, polypropylene resin, polyester resin, cellulose resin, vinyl chloride resin, polyvinyl alcohol, ethylene-vinylacetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, polyacrylonitrile or polyamide. The inorganic component may be selected, for instance, among aluminum, copper, iron, titanium, silver, calcium and other metals or alloys or intermetallic compounds containing these, silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, iron oxide and other oxides, calcium phosphate, calcium stearate and other inorganic acid salts or organic acid salts, glass and aluminum nitride, boron nitride, silicon carbide, silicon nitride and other ceramics.
For example, the microparticles 6 may be: acrylic microparticles, silica microparticles, boron silicate microparticles, calcium phosphate microparticles, calcium stearate microparticles, glass microparticles and charcoal powder microparticles. In accordance with a currently preferred solution, the micro-particles are selected from acrylic micro-particles and glass micro-particles.
Suitable micro-particles are for instance microbeads of acrylates such as Altuglas B100 (average particle size 30 microns) and Altuglas B130 (average particle size of 20 microns) from Arkema, solid glass micro-particles such as Spheriglass 2530 (average particle size of 65 microns), Spheriglass 3000 (average particle size of 35 microns), hollow glass microbeads such as Sphericel® 60P18 (average particle size of 20 microns) from Potters Industries, Eccospheres® SID230Z (average particle size of 55 microns) from Trelleborg or boron silicate microbeads such as iM30K from 3M (average particle size of 18 microns).
The multilayer film 1 herein claimed and more specifically the multilayer film according to the above embodiments may be manufactured by co-extrusion or extrusion coating, using either a round or a flat film die that allows shaping the polymer melt into a tubing or a flat film respectively.
In greater detail,
As shown in
According to an aspect of the invention, microparticles 6 are mixed with the thermoplastic polymer material P2 used for extrusion of the monolayer b or of the support layer of multilayer base layer B directly adhered to heat-sealable layer A, alternatively, the microparticles 6 are mixed with the thermoplastic polymer material P1 used for extrusion of the heat-sealable layer A.
The microparticles 6 may be compounded with a carrier resin to give a masterbatch which is then extruded with thermoplastic polymer material P1 and/or P2. Alternatively, the microparticles 6 may be dry blended with the respective thermoplastic polymer material P1 and or P2, without previous compounding.
The thermoplastic materials P1 and P2 (at least one of which embeds the microparticles 6) are moved by the respective first and second extruders 11, 12 to the die 13 and form the multilayer film 1. The multilayer film 1 prepared by co-extrusion as disclosed above presents a first external surface 2 which is not smooth, but rather presents a pattern characterized by protuberances emerging in correspondence of the areas of base layer B or of heat-sealable layer A where the microparticles are embedded, for example defining one of the films 1 shown in
In accordance with an optional variant the surface of the heat-sealable layer A not directly adhered to the base layer B may be coated with further coating layer. In the examples of figures in
To form the hydrophobic coating C, a hydrophobic coating composition C′ is applied to the rough surface of the heat sealable layer A not directly adhered to layer B by any standard coating method, such as for instance by gravure coating, smooth roll coating, direct gravure, reverse gravure, offset gravure, spray coating or dip coating. As an alternative, the coating C may be applied by vacuum deposition. In
The multilayer film 1 described above may be used to form various articles of packaging, which are briefly described herein below.
The articles of packaging obtained using the multilayer film 1 may be configured to define or cooperate to define an inner volume: by inner volume it is intended the volume V where a product will be hosted when the article of packaging is used. Note the article of packaging may be used alone to form the final package or in combination with other items, such as other films or supports of materials different from that of film 1. As such the inner volume may be entirely defined by the article of packaging formed with film 1 or in part by film 1 and in part by other components. In any case the first external surface 2 of the multilayer film 1 is destined to directly face the inner volume and to come into contact with the product: thanks to the accentuated roughness of the first external surface 2 of film 1 even in presence of contact between the first external surface 2 and the external surface of the product or between the first external surface 2 of film 1 and a surface of the same or other films, micro-passages are present allowing escape of gas, thus facilitating vacuumization of the package formed using the mentioned articles.
For example film 1 may be used to form the following articles for packaging:
Even if the multilayer film 1 described above is particularly configured for vacuum packaging, it can also be used for non-vacuum applications. This is the case, for example, of consumer-unit pouches filled with fluid products, which are emptied by the consumer by sucking the fluid product through a straw or a spout. Such pouches typically contain food or beverages, but may also be filled with pharmaceuticals such as cough syrups, fluid drug formulations, dietary supplements etc.
These pouches suffer from a similar problem as packages to be vacuumized: upon sucking, the two panels of the pouch tend to collapse against each other entrapping part of the fluid product in the bottom of the pouch and preventing it from flowing to the straw or the spout. This behavior is more evident with viscous fluids (e.g fluids with a viscosity higher than 100 mPa*s), such as fruit puree, smoothies etc. Under these circumstances, a mechanical manipulation from the user is needed to move the fluid product towards the straw/spout and effectively emptying the pouch. In the absence of such mechanical manipulation, emptying of the pouch results poor, and some product is wasted.
Thus, film 1 may be used to manufacture an article for packaging in the form of a pouch or a bag equipped with a spout or an accommodation for inserting a straw; the rough, first external surface 2 of the multilayer film 1 directly faces the inner volume of the pouch or bag, favoring the product evacuation.
In an embodiment, a hydrophobic or super-hydrophobic layer C may be present (at least in part) onto the first external surface 2 to further improve the emptying effectiveness of the pouch or bag.
In an embodiment, the multilayer packaging film 1 may comprise a thermoplastic multilayer base layer B, comprising at least an outermost anti-abuse layer 7 and an inner gas barrier layer 8. Further inner layers may also be present.
It is a further aspect of the invention a package or a set of packages 100 obtained using the multilayer film 1. For example, the package or packages 100 may be obtained using one of the articles for packaging 30, 40, 50, 60, 70, 80, 90 described above. Each package 100 has at least one product P housed in the seat or in the space defined inside the package(s). For example, the product P may be a food product such as a solid food product, a liquid food product, a gel food product, or a food product comprising a solid and/or a liquid and/or a gel portion. The package(s) 100 may be non-vacuum packages or vacuum packages and, in accordance with an option, vacuum skin packages. In particular, in accordance with an aspect, the package(s) are vacuumized and hermetically sealed, for example heat sealed, such that at least a portion of the first external surface 2 of the multilayer film 1 used for making the package 100 contacts the product P housed inside the package.
For example, as shown in in
In a variant, the package 100 of
Pouches or bags of this type may be obtained from a single multilayer film 1, formed into a tubing or a sheet and coupled or sealed, optionally heat sealed, for example at the peripheral border(s) thereof and around the spout or the accommodation for the straw. Alternatively, they may be obtained using two (or more) films coupled or sealed together, optionally heat sealed together, for example at the peripheral border(s) thereof and around the spout or the accommodation for the straw. One or both films may be formed by a multilayer film 1 of the invention. In any case, the first external surface 2 of the multilayer film(s) 1 used for forming the pouch or bag faces the inner volume of the pouch or bag in contact with the fluid product.
Advantageously, the fluid product may have a viscosity greater than 100 mPa*s. Fluid products with a viscosity below 100 mPa*s may generally easily be drawn through a spout or a straw incorporated into a pouch, but when viscosity is close to or beyond 100 mPa*s it becomes more difficult to void all the product before the panels of the pouch collapse and trap it in the lower portion of the pouch, requiring human mechanical action to move it upward towards the spout or the straw. In bags or pouches comprising the multilayer film 1, a passageway is created when the panels of the pouch collapse upon one another, which allows the fluid product, even with a viscosity above 100 mPa*s, to pass and reach the spout or the straw with continued suction.
Typically, the viscosity of the fluid product should not exceed 1000 mPa*s, as drawing such viscous products via suction would require an excessive effort. Thus, in embodiments, the fluid products may have a viscosity below 1000 mPa*s, preferably comprised between 100 mPa*s and 1000 mPa*s. Viscosity values are intended to be measured at room temperature (25° C.).
Examples of fluid products which can benefit from being packaged in bags or pouches comprising the multilayer film 1 may be fruit juices, fruit purees, applesauce, smoothies, yogurts, whole eggs, soups, baby foods, milk, coffee, soft drinks, energy drinks, and beverages in general, pharmaceuticals such as cough syrups, fluid drug formulations, dietary supplements.
In some embodiments, especially for packaging fluid products with viscosities in the upper portion of the indicated range, it may be advantageous that the first external surface 2 of the multilayer film(s) 1 used for forming the pouch or bag be coated with a hydrophobic or super-hydrophobic layer C to further improve the evacuation of the pouch or bag.
In the example of
The tray of
Furthermore, in accordance with a variant of the package 100 of
Several exemplifying processes of packaging using the multilayer film 1 or the article for packaging 30, 40, 50, 60, 70, 80, or 90 are disclosed below.
In accordance with certain general aspects, packaging processes disclosed herein comprise:
The process also provides for placing one or more products, optionally food products, inside the mentioned inner volume(s): in this respect, as it will appear in the following detailed description of certain specific processes, either the volume or volumes are first formed and then the product or products placed therein or the volume or volumes are defined during or even after positioning of the product in proximity of the multilayer film 1 or one of articles article 30-90.
Once a product is placed in the respective volume, the process may provide for a step of evacuating gas from the inner volume; during gas evacuation, a portion of the first external surface 2 of the at least one multilayer film 1 adheres to the one or more products (i.e. contacts the external surface of one or more products contained in the volume), without blocking the passage of gas: rather, thanks to the presence of the microparticles within the multilayer film 1 which provide an extremely corrugated surface 2, micro-passages are defined between the first external surface and the product surface allowing gas to pass through and thus, facilitating gas evacuation. Note the multilayer film 1 used in the process may also adhere to another portion of the first external surface of the same film or to the external surface of another film or a support used to form the package still leaving micro-passages between the two contacting surfaces and thus facilitating the process of gas evacuation and avoiding or minimizing the problem of bubbles of gas remaining trapped in the package under formation.
Once gas evacuation is completed, it is possible to proceed with hermetically sealing, optionally heat sealing, portions of said multilayer film 1 or of said article 30-90 forming one or more vacuum packaged products.
In a currently preferred variant the step of hermetically sealing is obtain by heat sealing. In greater detail, depending upon the design of the package (which may for example use just one multilayer film 1 according to aspect of the invention or two multilayer films 1 or one multilayer film 1 shaped to define a tray) the step of heat sealing may comprise one of the following alternatives.
Note that, according to a possible variant, during gas evacuation the at least one multilayer film may be draped down onto the product and form a plastic skin around the product or part of the product and, in case the package includes a support or tray, also onto part of a surface of a support or tray not occupied by the product thus forming a vacuum skin package.
After the above description of certain general aspects of the processes disclosed herein, here below a more detailed description is provided of several exemplifying processes using the multilayer films 1.
In accordance with a first example, (see
The tubular article 30, 40 made from multilayer film 1 is advanced according to step-by-step motion along a predetermined path, which may be for example a vertical or horizontal path. A transversal seal 102 (in the exemplified case a transversal heat seal) across the seamless tubing 30 or longitudinally sealed tubing 40 is formed at each step by a transverse sealing station 200 (for example comprising one or two movable heat bars, at least one of which is transversally movable relative to tubing 30 or 40) to define a seat or space 103 receiving a respective product P therein. While the article 30, 40 is being advanced, products may be located at different and spaced apart locations inside the inner volume of the tubular article and then the seats or spaces formed by consecutive transversal seals. Alternatively, at each step of advancement of the tubular article 30, 40, first a transversal seal is formed to define at least one receiving seat or space 103 and then the product P is positioned or poured into the receiving seat or space 103 (as in the case of a vertical machine for packaging particulate products, liquid product, gel products or mixtures thereof). The receiving seats or spaces 103 formed as described above present an opening 103a, for example an open end or a through hole formed through the wall of the article and communicating with the inside of the seat or space, such that gas may then be evacuated from the seat or space 103 via the opening 103a. Once gas is evacuated from the receiving seat or space the process provides a step of hermetically closing the evacuated open seat or space and forming a vacuumized closed package 100.
In the example shown in
The above cycle is repeated at each advancement step of the tubular article 30, 40 forming a sequence of closed packages 100. If the packages are not separated during their formation (for example using a heating bar with a cutter) they may be separated from one another at a dedicated cutting station 201 comprising for example a blade synchronized with the advancement of the tubing 30, 40 and with the heat bar 200.
In a possible first variant of the above first example, also shown in
In a possible second variant of the first example, again referring to
According to an aspect, which may be applicable to any one of the processes of packaging described above, the step of evacuating gas may comprise positioning at least one suction nozzle 300 at the opening 102 of each bag or pouch 100 under formation (reference is made to
In accordance with an optional aspect shown in
A second example of a process according to the invention is described below with reference to
For example, the products P may be positioned relative to article 50 before or while the transversal seals 402 are formed at a supply station (not shown) operative upstream the sealing station 401 shown in
Then, the process provides for a step of moving the open packages 405 to a vacuumization station 400 and of inserting the open sides 404 of each seat or space (and thus the open ends 406 of each package) in a vacuum chamber 409 of the vacuumization station 400, which is positioned along said predetermined path, while keeping the part of each seat or space (and thus of each package) housing the product outside the vacuum chamber 409: for example the part of each package hosting the product may rest of the top surface 407 of a conveyor 408 (for example a conveyor belt) positioned adjacent to the vacuum chamber 409, this latter having an elongated conformation and an elongated slit 409a for receiving the terminal neck 410 of each package 405 such that the package opening at the package open side or end 406 is entirely hosted inside the vacuum chamber 409. The vacuum chamber 409 is connected with a vacuum source 411, such that as soon as the packages P have their respective open ends or sides inside the vacuum chamber 409 and while the conveyor 408 moves the packages P from an upstream end to a downstream end of the vacuumization station 400 a step of evacuating gas from the seats or spaces 403 via the open sides/end 406 inserted inside said vacuum chamber progressively takes place.
As the packages arrive at the downstream end of the vacuumization station 400, most of the gas inside each package has been removed and thus a step of forming a longitudinal seal (for example a band seal directed parallel to the direction of movement of the packages along the determined path); the longitudinal seal may be a longitudinal heat seal and may take place at a sealing unit 412, which may be positioned in line with the vacuumization station 400; the sealing unit 412 hermetically closes the open sides/end 406 of the evacuated seats or spaces, thus forming closed packages extending between consecutive transversal seals 402. Note the sealing unit 412 may comprise a heated roller or heated belts or heating pads other heating means suitable for the purpose of operating as described above. The process also comprises a step of separating the vacuumized and sealed packages from one another. Note that in principle the step of separating the packages from each other could take place before the final sealing of the packages and also before vacuumization or at a distinct station operative after sealing of the packages.
During the described process, the first external surface 2 of the multilayer film 1 forming the packages contacts the external surface of the product P: the surface roughness induced by the presence of the microparticles provides a non-smooth external surface 2, which also in case of contact with the product surface leaves micro-passages, between the two contacting surfaces, useful for improving gas evacuation.
A third example of a process according to the invention is described below with reference to
After placing one or more products P, optionally food products, inside each pouch or bag 60, an open end 61 of the flexible container 60 is inserted inside a vacuum chamber 500, while keeping the part 62 of each flexible container housing the product P outside the vacuum chamber. By operating a vacuum source 501 (e.g., at least one vacuum pump) connected with the vacuum chamber, gas is evacuated from the volume 502 inside the vacuum chamber and thus from the inner volume V of the flexible container 60.
Once gas evacuation from the flexible container 60 has been completed, a sealer 503 such as a heat sealer (for example comprising one or more heat bars or one or more heat rollers or one or more heat pads or other heat sealing devices) is operated for forming a seal, optionally a heat seal, hermetically closing the open end 61 of the evacuated flexible container 60 thus forming a vacuum package.
Also in the third example, during the described process the first external surface 2 of the multilayer film 1 forming the flexible containers 60 contacts the external surface of the product P hosted therein: the surface roughness induced by the presence of the microparticles provides a non-smooth external surface 2, which also in case of contact with the product surface leaves micro-passages, between the two contacting surfaces, useful for improving gas evacuation.
A fourth example of a process according to the invention is described below with reference to
The first chamber 601 may be provided with a pressure sensor 611 and the second chamber 602 may be provided with a pressure sensor 612. Both pressure sensors are connected to a control unit 610 and are configured to provide the control unit 610 with a respective control signal indicative of a corresponding pressure in the first and second chambers, respectively. The control unit is configured to receive the control signals from the pressure sensors 611, 612 and to process the signals in an evacuation process (e.g. involving controlling a vacuum pump 609 to supply a vacuum pressure and/or to increase or decrease the vacuum pressure).
The vacuum device 600 further comprises a vacuum pump 609 optionally with a control valve 608. The vacuum pump 609 and control valve 608 are connected to the first chamber 601 by a vacuum line 607 configured to evacuate the first chamber by putting the vacuum pump and the first chamber into fluid communication with one another. The vacuum pump 609 and the control valve 608 are connected to the control unit 610 and configured to receive control signals from the same control unit. The control unit 610 is configured to control one or more different components (e.g. pump 609, valve 608) based on an evacuation process and depending upon signals received from one or more different sensors (e.g. sensors 611, 612).
At least the second chamber 602 is configured to open and close in order to allow for the flexible container (such as a bag or pouch 60 containing a product P to be packaged) to be introduced into the second chamber for evacuation and for it to be removed from the second chamber after evacuation. In order to insert the flexible container, the second chamber is opened and the flexible container placed into the second chamber in a manner that allows for the neck 65 of the container 60 to be introduced/inserted into the gap 604 so as to have the flexible package open end 61 positioned in the first chamber 601. Finally, the second chamber 602 is closed again and the evacuation process can be started.
It is noted that the individual manner in which the flexible containers are placed into the first and second chambers and the individual mechanisms for opening/closing the first chamber and/or the second chamber may be selected based on the individual application and based on the properties of the flexible containers and/or of the products P.
Generally, the control unit 610 is configured to control the vacuum pump and/or the control valve in order to provide the first chamber with a vacuum pressure below an ambient pressure. The vacuum pressure typically ranges from about or slightly below ambient pressure (at the beginning of evacuation) to about 1 to 20 mbar (upon completion of evacuation). In some embodiments, the target vacuum pressure ranges from about 1 mbar to about 20 mbar, preferably from about 1 mbar to about 10 mbar.
The fluid flow from the second chamber to the first chamber substantially depends upon the pressure differential between the pressures in the two chambers, as well as on the properties of the gap 604 (e.g. size, shape).
In order to evacuate the flexible container, the vacuum pressure applied to the first chamber causes gas/air from the second chamber to be drawn through the gap 604 into the first chamber 601. At the same time, the vacuum pressure applied to the first chamber causes gas/air from inside the package to be drawn through the bag neck 605 into the first chamber 601.
The absolute pressure in the first chamber is lower than the absolute pressure in the second chamber. Further, the absolute pressure in the package is also lower than the absolute pressure in the second chamber because the bag neck extending into the first chamber provides for a fluid flow from the inside of the package into the first chamber, which is less restricted or offers less resistance in comparison to the fluid flow from the second chamber into the first chamber.
Further, gas/air is also pushed out from the package due to the pressure in the second chamber being higher than the pressure inside the package, thereby applying compressive forces on an external surface of the package.
Upon completion of the evacuation of the package a sealer 606 (e.g. sealing bars) can be controlled to seal the flexible, for example by heat-sealing.
Also in the fourth example, during the described process the first external surface 2 of the multilayer film 1 forming the flexible container contacts the external surface of the product P hosted therein: the surface roughness induced by the presence of the microparticles provides a non-smooth external surface 2, which also in case of contact with the product surface leaves micro-passages, between the two contacting surfaces, useful for improving gas evacuation.
A fifth example concerns a process of packaging operated by a packaging line 700, which is described below with reference to
The bottom film 1′ is received at the thermoforming station 701 which forms tray shaped elements 703 in the bottom film 1′: each tray shaped element defines at least one respective seat 704 for receiving a product P; the process provides then for positioning, at a product loading station 705, at least one respective product P in each one of the seats 704 of the tray shaped elements 703; at the same time, the process provides for advancing a top film 1″ (the top film may be made by a multilayer film 1 according to one of the above described embodiments) towards the packaging station 702 where consecutive portions of the top film 1″ and of the bottom film 1′ (this latter with the formed tray shaped elements 703 defined therein) are received.
At the packaging station 702 consecutive portions of the top film 1″ are aligned above corresponding portions of the bottom film 1′ having one or more tray shaped elements, and then gas is evacuated from the volume between said aligned portions of the top film and of the bottom film. This step takes place in a closed vacuum chamber 706 which is periodically opened to allow access of the portions of the top and bottom film which are moved with a step-by-step movement in synchrony with opening and closing of the vacuum chamber 706 of the packaging station 702. Then sealing, optionally heat sealing, of the aligned portions of the top film and of the bottom film takes place to form one or more vacuum packages 707.
Once the packages are formed they may be separated the one or from the other at a severing station 708. The separation step may alternatively take place in the vacuum chamber of the packaging station or at a dedicated station not part of packaging line 700.
Depending upon the alternatives either the bottom film 1′ or the top film 1″ or both is/are formed by/using a multilayer film 1 according to the embodiments disclosed. In case the bottom film 1′ is formed with multilayer film 1 the first external surface 2 of the multilayer film 1 used forms part or the entirety of a top surface of the bottom film; in case the multilayer film 1 is used for forming or is comprised in the top film 1″, then the multilayer film 1 first external surface 2 forms part or the entirety of a bottom surface of the same top film 1″.
A sixth example concerns a process of packaging operated by a packaging line 800, which is described below with reference to
In detail at the packaging station the following steps take place:
Note the one or more trays 801 may be formed by or comprise a multilayer film 1 according to one of the above described embodiments: in this case the first external surface of the multilayer film forms part or the entirety of a top surface of the one or more trays.
Also or alternatively the top film may be formed or comprise a multilayer film 1 according to one of the above described embodiments: in this case the first external surface of the multilayer film forms part or the entirety of a bottom surface of the top film.
The process of the second variant of
In the processes of the fifth and sixth examples, the first external surface 2 of the multilayer films 1 (which may be used for forming the tray-shaped elements 703 or the trays 801, and/or the top film 1″, 806) contacts the external surface of the product P hosted in the packages under formation: the surface roughness induced by the presence of the microparticles in the multilayer film(s) 1 provides a non-smooth external surface 2, which also in case of contact with the product surface (or in case of contact between the top film and the tray/tray-shaped elements) leaves micro-passages, between the two contacting surfaces, useful for improving gas evacuation.
In the case of bags/pouches which are not vacuumized, the packaging processes may comprise the steps of:
| Number | Date | Country | Kind |
|---|---|---|---|
| 22155772.1 | Feb 2022 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2023/051106 | 2/8/2023 | WO |
