Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/12—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of paper or cardboard
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/10—Packing paper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/82—Paper comprising more than one coating superposed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
  • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
  • B32B37/24—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer not being coherent before laminating, e.g. made up from granular material sprinkled onto a substrate
  • B32B2037/246—Vapour deposition
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
  • B32B2260/04—Impregnation, embedding, or binder material
  • B32B2260/046—Synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
  • B32B2264/10—Inorganic particles
  • B32B2264/102—Oxide or hydroxide
  • B32B2264/1021—Silica
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/402—Coloured
  • B32B2307/4023—Coloured on the layer surface, e.g. ink
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/732—Dimensional properties
  • B32B2307/737—Dimensions, e.g. volume or area
  • B32B2307/7375—Linear, e.g. length, distance or width
  • B32B2307/7376—Thickness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2311/00—Metals, their alloys or their compounds
  • B32B2311/24—Aluminium

Definitions

• the present invention concerns a packaging paper-based material having high barrier properties to moisture and oxygen, and being recyclable in the recycling paper stream.
• Plastic packaging is used frequently in the economy and in people's daily lives. It has multiple advantages, such as its flexibility and its light weight. Such a
• 1 weight reduction contributes to fuel saving and CO2 reduction during transport, for example. Its barrier properties help to reduce food waste due a positive effect on increasing shelf life. The barrier properties also help to secure food safety.
• PVDC polyvinylidene chloride - or dichloride -
• WO 9211952 A1 in the name of the DUPONT de NEMOURS Company discloses a metallized material having a metallic coating on one or more surfaces that shows improved barrier layer coating adhesion and heat seal properties.
• These materials include a coating of polyvinylidene copolymer of at least 80 % vinyl idene chloride (PVDC), at least 4 % of an ethylenically unsaturated acrylic monomer, as well as coating additives for modifying film properties.
• PVDC achieves an excellent resistance to mechanical stress, while providing good oxygen barrier properties.
• the inventors have found that by mixing PVDC with additives, they could achieve a reasonably good bond between the metallic layer and the PVDC oxygen-barrier layer. More precisely, the metallized materials described in WO'952 show improved barrier layer coating adhesion
• the polyvinylidene chloride copolymer comprises at least 80% by weight polyvinylidene chloride, at least 4% by weight of an ethylenically unsaturated acrylic ester.
• a barrier multilayer packaging material structure being formed as a flexible or semi-rigid unitary sheet and comprising from its outer surface to its inner surface, the following layers:
• a pre-metallization layer located between the paper layer and the metal layer, said layer being present in an amount comprised within the range of 1 to 10 g/m 2 ,
• a thin metal layer selected within the list of: physical vapour deposition of aluminium having an optical density equivalent of 1.5 to 4, physical or chemical vapor deposition of aluminium oxide (AIOx) or silicon oxide (SiOx), said metal or oxide layer having a thickness comprised between 7 nm and 100 nm,
• a polymeric binder selected from the list of: pure ethylene- acrylic acid, pure methacrylic acid copolymer, pure polyester, pure polyvinyl acetate, pure polyurethane, said binder being present in an amount comprised between 0.1 g/m 2 and 10 g/m 2 ,
• PVDC polyvinylidene chloride
• the PVDC layer is pure, its barrier and heat resistance capabilities are not modified and proved to be excellent, unlike prior art structures wherein the PVDC chemical structure was modified by additives. Furthermore, the presence of an intermediate binding layer between the metal and the PVDC layers was found to provide an excellent adhesion between these two layers. None of the solutions available in the known art was able to provide all such benefits at the same time.
• the pre-metallization layer allows the metal layer to correctly adhere to the surface of the paper, especially as it smoothens the surface of the paper, and provides a chemically compatible interface for the metal atoms to be deposited.
• inner side of the packaging structure it is meant the side intended to face the filled food contents of a package produced from said packaging structure.
• PVDC polyvinylidene chloride
• layer of pure ethylene acrylic acid or “pure” methacrylic acid, it is meant that said layer is entirely and exclusively constituted of, respectively, ethylene- acrylic acid or methacrylic acid, and especially that it contains only one type of polymer, and is deprived of any other type of polymer or ingredient.
• the multi-layer metallized paper-based material according to the present invention can be recycled with other paper packaging materials in a regular paper recycling process, preferably in a process according to the according to PTS test method PTS-RH 021:2012 Category II.
• a regular paper recycling process preferably in a process according to the according to PTS test method PTS-RH 021:2012 Category II.
• Such a possibility is due to the fact that, although it contains a certain amount of polymer (HDPE), this polymer is applied by a dispersion coating process.
• HDPE polymer
• dispersion coating of the polymer layer the overall thickness of polymer material in the structure is extremely reduced, compared to the thickness of paper material; therefore the inventors have achieved a packaging multilayer structure with excellent barrier properties against oxygen and moisture transfer, as well as resistance to liquid contact, while achieving a total contents of cellulosic fibres which is very high in proportion of the total material weight. Furthermore, dispersion coating of polymer avoids high cohesion and high adhesion of the polymer and therefore solves the recyclability problem (solid particles of polymer dispersed in a water carrier medium instead of liquid polymer applied to substrate).
• the total fiber contents of said structure is comprised between 85% and 95% by weight.
• the packaging structure further comprises an outermost coating layer comprising: an ink printing, an overprint varnish, said outermost layer being applied in an amount comprised between 0.1 g/m 2 and 6 g/m 2 .
• the pre-metallization layer comprises an ingredient selected within the list of: ethylene acrylic acid copolymer, polyvinyl alcohol (PVOH), butenediol vinyl alcohol (BVOH) copolymer, nitrocellulose-propylene-acrylic acid copolymer, polyurethane, or a combination thereof.
• ethylene acrylic acid copolymer polyvinyl alcohol (PVOH), butenediol vinyl alcohol (BVOH) copolymer, nitrocellulose-propylene-acrylic acid copolymer, polyurethane, or a combination thereof.
• the pre- metallization layer is preferably applied by a polymer dispersion coating process, more preferably using direct or reverse gravure application or semi-flexography process.
• the packaging structure of the invention can also advantageously comprise an innermost layer with a heat seal lacquer, a liquid-tight polyolefin dispersion coating, or a combination thereof, said innermost layer being present in an amount comprised between 1 and 10 g/m 2 .
• the present invention is further directed to a package made of a paper- based barrier multilayer structure as described above.
• Figure 1 is a schematic representation of a cross-section of a first embodiment of a multilayer barrier structure according to the invention
• Figure 2 is a schematic representation of a cross-section of a second embodiment of a multilayer barrier structure according to the invention.
• extrusion coating it is meant a method to provide a thick layer of polymer by using an extruder which forces melted thermoplastic resin (e.g. polyethylene) through a horizontal slot-die onto a moving web of substrate (e.g. paper).
• thermoplastic resin e.g. polyethylene
• substrate e.g. paper
• extrusion lamination it is meant a similar process to extrusion coating, whereby a polymer resin is extruded between two substrates (e.g. a layer of paper and another layer of polymeric film), and acts as a bonding agent.
• adhesive lamination it is meant a process whereby one paper material is coated with adhesive and laminated to a second paper or paperboard material.
• dispersion coating or “polymer dispersion coating” it is meant a coating technique whereby an aqueous dispersion of fine polymer particles or polymer solution is applied to the surface of paper or board as such, in order to form a solid, non- porous film after drying.
• Dispersion coating can be performed by gravure, flexo-gravure, rod, blade, slot-die, curtain air knife, or any other known method of paper coating.
• Dispersion coating can create a much thinner layer than extrusion, since the polymer is mixed in an aqueous water solution. This brings advantages in terms of quantity of polymer usage, its barrier performance and recyclability of resulting paper structure.
• the target of dispersion coating is to achieve a barrier layer against water, water vapour, grease, oil, gas, etc. by environmentally friendly coating. Another target is to prepare surface of cell ulosic material for a vacuum deposition process
• figure 1 a first embodiment of the invention.
• a multilayer structure 1 comprising the several layers, described in the following, starting from the outer layer (i.e. the layer which is in contact with outside atmosphere, once said structure is formed into a package), then towards the inner layer (i.e. the layer that will eventually be in contact with the packed product, once said structure is formed into a package).
• the first - outermost - layer 2 is a flexible or semi-rigid paper layer having a grammage of 80 g/m 2 .
• the paper is an uncoated woodfree supercalendered kraft paper obtained from the UPM Company.
• the paper-based barrier multilayer structure 1 further comprises a pre-metallization layer 3 of butenediol vinyl alcohol (BVOH) copolymer, located
• pre-metallization layer 3 being applied by polymer dispersion coating, in an amount of about 3 g/m 2 .
• the pre-metallization layer 3 is metallized with a thin metal layer 4 which is a physical vapour deposition of aluminium having an optical density equivalent of 3, said aluminium layer having a thickness of about 45 nm.
• a polymeric adhesion primer coating 5 comprising a water-based dispersion of polyester, said primer (also named “binder” in the rest of this specification) being applied in an amount of about 2 g/m 2 by a dispersion coating process.
• the innermost layer of the structure 1 is a water resistant oxygen-barrier layer 6 of pure polyvinylidene chloride (PVDC), being applied in an amount of about 8 g/m 2 and which is deposited by a polymer dispersion coating process using direct gravure application.
• PVDC polyvinylidene chloride
• the structure is similar to that of the first embodiment described above in relation to figure 1.
• the paper-based barrier multilayer structure 1 further comprises an outermost coating layer 7 comprising an ink printing and an over-print varnish in an amount of about 5 g/m 2 .
• the PVDC layer serves as a heat seal lacquer in case the material requires sealing in a heat sealing process, in particular for manufacturing a package therefrom.
• the flexible packaging material structure of the present invention is designed to be formed into a packaging material for a food product. It is preferably a primary packaging material, but can also be used to manufacture a secondary packaging
• a primary packaging material for a food product is in direct contact with the actual food product.
• a secondary packaging material for a food product may be a packaging material for a food product that helps secure one or more food products contained in a primary packaging. Secondary packaging material is typically used when multiple food products are provided to consumers, each individually packed in a single container.
• a tertiary packaging material for a food product is a packaging material for a food product that helps secure one or more food products contained in a primary packaging and/or in a primary and secondary packaging during transport.

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• Laminated Bodies (AREA)
• Wrappers (AREA)

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Applications Claiming Priority (2)

Publications (1)

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ID=75914343

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Cited By (3)

Citations (4)

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• 2022
  • 2022-05-09 MX MX2023012207A patent/MX2023012207A/es unknown
  • 2022-05-09 WO PCT/EP2022/062391 patent/WO2022238280A1/en not_active Ceased
  • 2022-05-09 US US18/560,143 patent/US20240227361A1/en active Pending
  • 2022-05-09 JP JP2023563877A patent/JP2024518885A/ja active Pending
  • 2022-05-09 EP EP22728177.1A patent/EP4337827B1/en active Active
  • 2022-05-09 BR BR112023021615A patent/BR112023021615A2/pt unknown
  • 2022-05-09 CN CN202280028770.XA patent/CN117203395A/zh active Pending

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