• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention is directed to a packaging material free from aluminium in the form of a continuous foil or film, comprising a layer of microfibrillated cellulose (MFC), wherein the layer comprising MFC has been laminated or coated on at least one side with a heat-sealable material. The MFC layer contains at least 60% by weight of microfibrillated cellulose. The present invention is also directed to a method for induction sealing, wherein a packaging material to be heat-sealed by induction is placed against an induction heating surface.
    公开号:SE1751595A1
    申请号:SE1751595
    申请日:2017-12-21
    公开日:2019-06-22
    发明作者:Esa Saukkonen；Isto Heiskanen；Jukka Kankkunen；Kaj Backfolk
    申请人:Stora Enso Oyj；
    IPC主号:
    专利说明:

    HEAT-SEALABLE PACKAGING MATERIAL Technical field The present invention is directed to a heat-sealable packaging material freefrom aluminium in the form ofa continuous foil or film, comprising a layer ofmicrofibrillated cellulose (MFC), wherein the layer comprising MFC has beenlaminated or coated on at least one side with a heat-sealable material. TheMFC layer contains at least 60% by weight of microfibrillated cellulose. Thepresent invention is also directed to a method for induction sealing, wherein apackaging material to be heat-sealed by induction is placed against aninduction heating surface.
    Background Packages used for sensitive objects such as liquid beverages need to havesufficient barrier properties. Typically, aluminium is used for these purposesand generally provides sufficient properties with regard to penetration of gas,such as oxygen. The aluminium layer is also an aroma barrier and plays an important function in heat sealing.
    Heat sealing is used in packaging primarily for producing or closing wraps,bags, pouches, cartons, tubes, blister packs, thin wall containers, kits and various components.
    There are several methods useful for heat sealing, including impulse sealing,dielectric heat sealing and thermal heat sealing. 2 lnduction is commonly used as a means to heat seal packages. This istraditionally based on the presence of a sufficient amount of conductivematerial to generate heat and thereby enable heat sealing.
    One issue with the use of aluminium is that it poses an environmentalchallenge, is a problem in the recycling process and is not compostable. ltwould therefore be desirable to replace aluminium with renewable materials.However, it is essential to maintain the barrier properties of the packagingmaterial to the extent it is to be used in packages for e.g. liquids and it is alsoimportant that the packaging material is sufficiently crack-resistant.
    Many packaging lines and units are equipped with induction sealers. Thismeans also that the packaging materials must contain an aluminium layer or a foil (or similar materials) in order to be induction sealable.
    The use of an aluminum layer provides good barrier properties, but is leadingto problems in respect of sustainability value, recycling, and costs.
    Embedding substances that enable induction sealability of a polymer film orcoating or biofilm is an option, but can also lead to problems in performance,recyclability and costs. Addition of functional chemicals or particles to, forexample, wet end or coating process might be an option but this mightincrease the risks of negatively influencing barrier properties or laminate or barrier manufacturing process.
    Therefore, an aluminium free coating or a film without embedded inductivesubstances which can still be used in induction sealing without being damaged due to the heat sealing process is needed.
    Summary of the invention lt has surprisingly been found that by using a layer of microfibrillated cellulose(MFC) wherein the layer comprising MFC has been laminated or extrusioncoated on at least one side with a heat-sealable material, it is possible toachieve a packaging material suitable for heat sealing using methods suchas, but not limited to, induction sealing, even when the packaging material is free from aluminium in the form ofa continuous foil or film.
    The present invention is thus directed to a packaging material that is free fromaluminium in the form of a continuous foil or film, comprising a layer of MFC,wherein the layer comprising MFC has been laminated or coated on at leastone side with a heat-sealable material. The heat-sealable material may be provided on one or both sides of the MFC layer.
    To facilitate the induction sealing, one side of the packaging material mayoptionally be provided with a coating that does not adhere to or stick tosurfaces, specifically metal surfaces such as aluminum surfaces whenheated. Thus, that coating prevents the coated surface from adhering to aheated metal surface. Examples of such coatings include starch, a Wax, amineral or pigment coating or a polymer having a higher melting point thanthe heat-sealable material. lf the coating that prevents the coated surfacefrom adhering to a heated metal surface is a polymer, it may also contain oneor more antisticking and/or antiblocking agents, to further reduce the risk ofadhering to the metal surface. The coating that does not adhere to or stick tosurfaces is preferably provided in an amount of up to 20 g/m2, such as from0.1 g/m2 to 20 g/m2, preferably 0.5 g/m2 to 15 g/m2 or 0.5 g/m2 to 5 g/m2.Alternatively, the packaging material does not adhere to a heated metalsurface. 4 The packaging material according to the present invention has a thickness ofless than 50 pm, such as less than 45 pm, less than 40 pm, or less than 35 pm.
    The layer of MFC is preferably in the range of from 5 to 50 gsm, such as from5-30 gsm or from 10-30 gsm. The MFC may be native or modified and maybe a mix of native and modified MFC as well as a mix of native MFC anddifferent types of modified MFC. lf the MFC is modified it may bephosphorylated or PCC coated MFC. The MFC may be produced from pulp, such as from dissolving pulp.
    The layer of MFC has an OTR (oxygen transmission rate) value of less than500 cm3/m2*day at 23°C/50%RH for a 20-30 gsm MFC layer. Preferably, theOTR value is less than 450 cm3/m2*day at 23°C/50%RH. More preferably, theOTR value is less than 400 cm3/m2*day at 23°C/50%RH, less than 200cm3/m2*day at 23°C/50%RH or less than 100 cm3/m2*day at 23°C/50%RH.The OTR can be determined using methods known in the art.
    The layer of MFC in combination with the heat-sealable material according tothe present invention has an OTR (oxygen transmission rate) value of lessthan 400 cm3/m2*day at 23°C/50%RH. Preferably, the OTR value is less than300 cm3/m2*day at 23°C/50%RH. More preferably, the OTR value is less than100 cm3/m2*day at 23°C/50%RH. The OTR can be determined using methods known in the art.
    The packaging material according to the present invention can be subjectedto printing through a reel to reel or reel to sheet or sheet fed printing process,but can also be subjected to off-line surface treatment with other technologiessuch as flexogravure, rotogravure, reverse rotogravure, silk screen printing,inkjet printing, offset printing (lithography), spray, curtain, foam or other printing or surface treatment techniques. 5 The packaging material according to the present invention may bebiodegradable and/or compostable. ln this context, compostability is definedin accordance with ISO 18606, i.e. constituents in the whole material whichare present at concentrations of less than 1% do not need to demonstratebiodegradability. However, the sum of such constituents shall not exceed 5%.Biodegradability is defined as follows: the ultimate aerobic biodegradabilityshall be determined for the whole material or for each organic constituentwhich is present in the material at a concentration of more than 1% (by drymass). Constituents present at levels between 1 to 10% shall be tested individually.
    One aspect of the present invention is a method for induction sealing, whereinthe packaging material according to the present invention can be subjected toinduction sealing, even though the packaging material is free from aluminiumin the form of a continuous foil or film. ln this method for induction sealing, thepackaging material according to the present invention is brought into closeproximity or brought into contact with a surface that can be heated byinduction, such as a metal surface, such as an aluminium surface, which isarranged in such a way that it can be heated by induction and used to heatand thereby seal a packaging material, under applied pressure, according tothe present invention. Thus, according to this method, existing equipment forinduction heat sealing can readily be adapted for use in accordance with thepresent method for induction sealing of a packaging material according to thepresent invention. The heated surface may be an aluminium substrate or counterpiece.
    When carrying out the induction sealing, the packaging material is arrangedsuch that at least one of the two surfaces to be sealed together is providedwith a heat-sealable material. The heat from the heated surface is conductedthrough the packaging material and heats the heat-sealable material so that itsoftens or melts sufficiently to obtain the desired sealing. lf one side of thepackaging material is coated with a material that does not stick to surfaces, 6 then the side of the packaging material provided with the material that doesnot stick to surfaces is brought into close proximity or contact with the surfaceheated by induction. However, the packaging material according to thepresent invention may also be heat sealed to a surface which is not apackaging material according to the present invention.
    The packaging material according to the present invention can be used forany type of final packaging product where induction heat sealability isdesirable. ln particular, the packaging product according to the present invention can be used as a closure, lid, liquid packaging product or pouch.
    Detailed description The microfibrillated cellulose used according to the present invention can be prepared using methods known in the art.
    The term “free from aluminium in the form of a continuous foil or film” as usedherein in the context of a packaging material, means a packaging materialthat does not comprise aluminium in the form ofa continuous foil or film. lnthis context, foil or film has a thickness of at least 250 nm and is continuous,i.e. essentially free from pin holes. Thus, the packaging material typicallycomprises less than 2% by weight of aluminium, such as less than 1% by weight of aluminium or less than 0.5% by weight of aluminium.
    The MFC layer may be plasma treated or corona treated prior to adding theheat-sealable material. The heat-sealable material may be provided directlyon the MFC layer. Alternatively, one or more layers can be provided betweenthe MFC layer and the heat-sealable material. Such layers provided betweenthe MFC layer and the heat-sealable material may for example provideadditional barrier properties and/or improve the adhesion between the MFC layer and the heat-sealable material.
    The heat-sealable material is a material which can be provided as a layer andwhich has a melting point and/or a glass transition temperature such that it issuitable for use in heat-sealing. Examples of such heat-sealable materialsinclude thermoplastic polymers such as polypropylene or polyethylene.Further examples are waxes and hot melts. Additional examples includevinylic polymers (PVC and PVDC based), acrylate and styrene acrylate basedpolymers, acrylate/polyolefin copolymers, styrene copolymers, polyesters,polypropylene dispersions, ethylene copolymers (EAA and EMAA), ethyleneterpolymer (EVA) or styrene acrylic latex or styrene butadiene latex. Thus, theheat-sealable material can be applied as a coating, for example by dispersioncoating, extrusion coating or emulsion coating. The heat-sealable materialcan also be applied by printing.
    The layer comprising the heat-sealable material may also contain additivessuch as waxes / slip agents: Polyethylene wax, AKD, Carnauba wax, PTFE,Fatty acid ester; inorganic pigments / filler: silica, talc; antioxidants / UV-stabilizer/optical brighteners and antifoaming agents. ln one embodiment of the present invention, the MFC layer is formed in apaper making machine or according to a wet laid production method, byproviding a suspension onto a wire and dewatering the web to form anintermediate thin substrate or said film. A suspension comprisingmicrofibrillated cellulose is provided to form said film. ln one embodiment of the present invention, the MFC layer used inaccordance with the present invention can be made according to any knownprocesses described in the art such as wet laid methods, coating, printing, extrusion, lamination etc.
    Microfibrillated cellulose (MFC) shall in the context of the patent application mean a nano scale cellulose particle fiber or fibril with at least one dimension 8 less than 100 nm. MFC comprises partly or totally fibrillated cellulose orIignocellulose fibers. The liberated fibrils have a diameter less than 100 nm,whereas the actual fibril diameter or particle size distribution and/or aspectratio (length/width) depends on the source and the manufacturing methods.
    The smallest fibril is called elementary fibril and has a diameter ofapproximately 2-4 nm (see e. g. Chinga-Carrasco, G., Cellulose fibres,nanofibrils and microfibrils,: The morphological sequence of MFCcomponents from a plant physiology and fibre technology point of view,Nanoscale research letters 2011, 6:417), while it is common that theaggregated form of the elementary fibrils, also defined as microfibril (Fengel,D., Ultrastructural behavior of cell wall polysaccharides, Tappi J., March 1970,Vol 53, No. 3.), is the main product that is obtained when making MFC e.g. byusing an extended refining process or pressure-drop disintegration process. Depending on the source and the manufacturing process, the lengthof the fibrils can vary from around 1 to more than 10 micrometers. A coarseMFC grade might contain a substantial fraction of fibrillated fibers, i.e.protruding fibrils from the tracheid (cellulose fiber), and with a certain amountof fibrils Iiberated from the tracheid (cellulose fiber).
    There are different acronyms for MFC such as cellulose microfibrils, fibrillatedcellulose, nanofibrillated cellulose, fibril aggregates, nanoscale cellulosefibrils, cellulose nanofibers, cellulose nanofibrils, cellulose microfibers,cellulose fibrils, microfibrillar cellulose, microfibril aggregrates and cellulosemicrofibril aggregates. MFC can also be characterized by various physical orphysical-chemical properties such as large surface area or its ability to form agel-like material at low solids (1-5 wt%) when dispersed in water. Thecellulose fiber is preferably fibrillated to such an extent that the final specificsurface area of the formed MFC is from about 1 to about 300 m2/g, such asfrom 1 to 200 m2/g or more preferably 50-200 m2/g when determined for afreeze-dried material with the BET method. 9 Various methods exist to make MFC, such as single or multiple pass refining,pre-hydrolysis followed by refining or high shear disintegration or liberation offibrils. One or several pre-treatment step is usually required in order to makeMFC manufacturing both energy efficient and sustainable. The cellulosefibers of the pulp to be supplied may thus be pre-treated enzymatically orchemically, for example to reduce the quantity of hemicellulose or lignin. Thecellulose fibers may be chemically modified before fibrillation, wherein thecellulose molecules contain functional groups other (or more) than found inthe original cellulose. Such groups include, among others, carboxymethyl(CM), aldehyde and/or carboxyl groups (cellulose obtained by N-oxylmediated oxydation, for example "TEMPO"), or quaternary ammonium(cationic cellulose). After being modified or oxidized in one of the above-described methods, it is easier to disintegrate the fibers into MFC or nanofibrillar size fibrils.
    The nanofibrillar cellulose may contain some hemicelluloses; the amount isdependent on the plant source. Mechanical disintegration of the pre-treatedfibers, e.g. hydrolysed, pre-swelled, or oxidized cellulose raw material iscarried out with suitable equipment such as a refiner, grinder, homogenizer,colloider, friction grinder, ultrasound sonicator, fluidizer such as microfluidizer,macrofluidizer or fluidizer-type homogenizer. Depending on the MFCmanufacturing method, the product might also contain fines, ornanocrystalline cellulose or e.g. other chemicals present in wood fibers or inpapermaking process. The product might also contain various amounts ofmicron size fiber particles that have not been efficiently fibrillated.
    MFC is produced from wood cellulose fibers, both from hardwood or softwoodfibers. lt can also be made from microbial sources, agricultural fibers such aswheat straw pulp, bamboo, bagasse, or other non-wood fiber sources. lt ispreferably made from pulp including pulp from virgin fiber, e.g. mechanical,chemical and/or thermomechanical pulps. lt can also be made from broke or recycled paper.
    The above described definition of MFC includes, but is not limited to, the newproposed TAPPI standard W13021 on cellulose nanofibril (CMF) defining acellulose nanofiber material containing multiple elementary fibrils with bothcrystalline and amorphous regions.
    According to another embodiment, the suspension may comprise a mixture ofdifferent types of fibers, such as microfibrillated cellulose, and an amount ofother types of fiber, such as kraft fibers, fines, reinforcement fibers, syntheticfibers, dissolving pulp, TMP or CTMP, PGW, etc.
    The suspension may also comprise other process or functional additives,such as fillers, pigments, wet strength chemicals, dry strength chemicals,retention chemicals, cross-linkers, softeners or plasticizers, adhesion primers,wetting agents, biocides, optical dyes, fluorescent whitening agents, de-foaming chemicals, hydrophobizing chemicals such as AKD, ASA, waxes,resins etc. Additives can also be added using a size press.
    There are several methods for preparing a film of MFC, including wire formingand cast forming. ln wire forming, a suspension, comprising microfibrillatedcellulose, is dewatered on a porous surface to form a fibrous web. A suitableporous surface is e.g. wire in a paper machine. The fibrous web is then driedin a drying section in a paper machine to form the MFC film, wherein the filmhas a first side and a second side. The papermaking machine that may beused in the process according to the present invention may be any type ofmachine known to the skilled person used for the production of paper,paperboard, tissue or similar products, alternatively for example a modified or non-conventional papermaking machine.
    The furnish is placed onto the wire and then a web is formed, which may bedewatered to form an intermediate thin substrate or film. ln cast forming, thesuspension, comprising MFC, is for example applied on a supporting mediumwith a non-porous surface. The non-porous surface is e.g. a plastic or metal 11 belt on which the suspension is evenly spread and the MFC film is formedduring drying. The MFC film is then peeled off from the supporting medium inorder to form a stand-alone film, wherein the film has a first side and a second side.
    Preferably, the MFC layer is laminated or extrusion coated or dispersioncoated with a thermoplastic polymer which may be a bio-based and/orbiodegradable thermoplastic polymer. The thermoplastic film typically has amelting point of from 60°C to 220°C. ln one embodiment of the presentinvention, the thermoplastic polymer is selected from thermoplastic cellulose,thermoplastic starch (modified starch), polyethylene (PE), polypropylene (PP),high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear-low density polyethylene (LLDPE), polylactic acid (PLA), polycaprolactone,polyglycolide (PGA), ethylene vinyl acetate (EVA), ethylene vinyl alcohol(EVOH), polyamide (PA), ionomers (e.g. Surlyn) or combinations thereof.The thermoplastic film is typically present at at least 5 g/m2, such as at least15 g/m2, such as at least 20 g/m2 or at least 30 g/m2. ln one embodiment of the present invention, the MFC layer is laminated withthe thermoplastic polymer. The lamination can be carried out using methods known in the art.
    A final packaging product, such as a final liquid packaging board comprisingthe packaging material according to the present invention may compriseseveral layers, i.e. be a multilayer structure. The heat-sealable packagingmaterial according to the present invention is useful for example in packagesfor wrapping objects, bags, pouches, cartons, tubes, blister packs, thin wallcontainers etc. The packaging material according to the present inventionmay also be used as a seal or lid for a container, i.e. the packaging materialmay applied to seal the package, wherein the package may be manufacturedfrom any material on which the packaging material according to the presentinvention may provided as seal. ln one embodiment, the container to be 12 sealed with a packaging material according to the present invention maycontain a sufficient of aluminium in the area on which the seal is to provided, to allow heat sealing by induction. ln view of the above detailed description of the present invention, othermodifications and variations will become apparent to those skilled in the art.However, it should be apparent that such other modifications and variations 10 may be effected without departing from the spirit and scope of the invention.
    权利要求:
    Claims (1)
    [1] 1. -5, wherein said layer comprising microfibrillated cellulose has been extrusion coated or dispersion coated with a thermoplastic polymer. _ The heat-sealable packaging material according to claim 6, wherein said thermoplastic polymer is polyethylene. 14 8. The heat-sealable packaging material according to any one of claims1-5, wherein the microfibrillated cellulose is native or modified or amixture thereof and wherein the modified microfibrillated cellulose isphosphorylated microfibrillated cellulose or PCC coated microfibrillated cellulose. 9. A method of manufacturing a heat-sealable packaging materialaccording to any one of claims 1-8, comprising the steps ofa) preparing a layer of microfibrillated cellulose;b) laminating or coating the layer of step a) with a heat-sealable material on at least one side of the microfibrillated cellulose layer. 10. Use of a heat-sealable packaging material according to any one of claims 1-8 in induction sealing. 11.A method for induction sealing, wherein the material to be sealed byinduction is free from aluminium in the form of a continuous foil or film,wherein the packaging material according to any one of claims 1-8 isbrought into close proximity or brought into contact with a surface thatcan be heated by induction, thereby heating and sealing, under appliedpressure, a packaging product comprising a heat-sealable packaging material according to the present invention. 12.A method according to claim 11, wherein the sealing is achieved bysoftening or melting of the heat-sealable material and by a pressure applied to the softened or melted material.
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    同族专利:
    公开号 | 公开日
    CN111386196A|2020-07-07|
    BR112020012442A2|2020-11-24|
    CA3081813A1|2019-06-27|
    WO2019123290A1|2019-06-27|
    EP3727855A1|2020-10-28|
    US20210017717A1|2021-01-21|
    JP2021507829A|2021-02-25|
    SE542579C2|2020-06-09|
    EP3727855A4|2021-09-22|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US3445324A|1963-05-14|1969-05-20|Curwood Inc|Flexible wrapping material|
    IT1280393B1|1995-03-10|1998-01-20|Acma Spa|METHOD AND EQUIPMENT FOR THE WELDING OF THE OVERLAYED FLAPS OF A FILM IN HEAT-SEALABLE MATERIAL IN PACKAGING MACHINES|
    EP1161932B1|1996-05-13|2004-02-11|B. Braun Medical, Inc.|Flexible container and method of making same|
    AT507384B1|2008-09-18|2011-07-15|Westwind Verpackungen Gmbh|CLOSING DEVICE FOR CLOSING PREFERABLY BAGGED PACKAGING UNITS|
    SE534932C2|2009-12-21|2012-02-21|Stora Enso Oyj|A paper or cardboard substrate, a process for manufacturing the substrate and a package formed from the substrate|
    EP3350369B1|2015-09-17|2019-07-24|Stora Enso Oyj|A method to produce a film comprising microfibrillated cellulose and an amphoteric polymer|
    SE539754C2|2016-03-22|2017-11-14|Stora Enso Oyj|Oxygen barrier film and laminate and methods of manufacturing the same|SE1750411A1|2017-04-03|2018-10-04|
    CN111469512A|2020-04-14|2020-07-31|江阴申隆包装材料有限公司|Food is with repeated heat-seal film and repeated heat-seal packaging film thereof|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1751595A|SE542579C2|2017-12-21|2017-12-21|Heat-sealable packaging material|SE1751595A| SE542579C2|2017-12-21|2017-12-21|Heat-sealable packaging material|
    US16/955,900| US20210017717A1|2017-12-21|2018-12-19|Heat-sealable packaging material|
    BR112020012442-7A| BR112020012442A2|2017-12-21|2018-12-19|heat sealable packaging material|
    CN201880076263.7A| CN111386196A|2017-12-21|2018-12-19|Heat-sealable packaging material|
    JP2020532955A| JP2021507829A|2017-12-21|2018-12-19|Heat-sealable packaging material|
    EP18891959.1A| EP3727855A4|2017-12-21|2018-12-19|Heat-sealable packaging material|
    PCT/IB2018/060302| WO2019123290A1|2017-12-21|2018-12-19|Heat-sealable packaging material|
    CA3081813A| CA3081813A1|2017-12-21|2018-12-19|Heat-sealable packaging material|
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