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
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/10—Layered products comprising a layer of synthetic resin 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
• • 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
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
  • B32B27/288—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyketones
• • 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
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • 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
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/04—Interconnection of layers
  • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
• • 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
  • B32B2307/724—Permeability to gases, adsorption
  • B32B2307/7242—Non-permeable
• • 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
  • B32B2317/00—Animal or vegetable based
  • B32B2317/12—Paper, e.g. cardboard
• • 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
  • B32B2323/00—Polyalkenes
  • B32B2323/04—Polyethylene
• • 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
  • B32B2323/00—Polyalkenes
  • B32B2323/10—Polypropylene
• • 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
  • B32B2329/00—Polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals
• • 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
  • B32B2439/00—Containers; Receptacles

Definitions

• the present invention relates to a packaging laminate comprising a core layer of paper and a gas barrier layer of plastic.
• the present invention also relates to a method of producing the packaging laminate according to the invention, as well as packaging containers produced from the packaging laminate according to the invention.
• a large group of these single-use disposable packages is produced from a laminated packaging material comprising a core layer of paper or paperboard and outer, liquid-tight coatings of plastic on both sides of the core layer.
• composition of the packaging material is intended to afford to the packed product the best possible protection, at the same time as it is intended to render the package both easy to manufacture and easy to handle.
• a core layer of paper or paperboard imparts to the package good mechanical configurational stability such that the package may be distributed in a simple, rational manner and be conveniently handled, at the same time as outer, liquid-tight coatings of plastic effectively protect the core layer against penetration by moisture and wet which otherwise would rapidly weaken and destroy the core layer and thereby render the package sloppy and impossible to handle.
• the outer, liquid-tight coatings consist of a thermoplastic such as, for example, polyethylene which, in addition, gives the laminated packaging material excellent heat-sealing properties so that the packages may be closed and permanently sealed in the desired geometric configuration by means of conventional heat-sealing methods.
• a thermoplastic such as, for example, polyethylene which, in addition, gives the laminated packaging material excellent heat-sealing properties so that the packages may be closed and permanently sealed in the desired geometric configuration by means of conventional heat-sealing methods.
• Packaging containers from such a laminated packaging material are often produced in that a continuous web of the packaging material is reformed into a tube by the longitudinal edges of the web being united to one another, whereafter the tube is filled with intended contents and is sealed along repeated transverse sealing zones.
• the package units containing their contents are separated from the tube by means of incisions in the transverse sealing zones and are formed to the desired geometric configuration by a fold-forming operation.
• Alifoil aluminium foil
• a layer of a polymer possessing superior gas barrier properties may be employed as the gas barrier layer.
• gas barrier polymers are ethylene vinyl alcohol copolymers (EVOH), polyvinyl alcohol (PVOH) and polyamide.
• Such polymers possess superior gas barrier properties, but must, because of their sensitivity, be protected against moisture and wet, for example by being encapsulated in between layers of a liquid-tight polymer such as, for example, polyethylene.
• a liquid-tight polymer such as, for example, polyethylene.
• the prior art conventional gas barrier layers are relatively expensive, which entails a higher manufacturing cost per package.
• One object of the present invention is therefore to realise a novel packaging laminate of the type described by way of introduction, without any consequential problems of the type linked to the prior art technology.
• Another object of the present invention is to realise a well-integrated packaging laminate possessing superior gas barrier properties at a lower cost.
• Yet a further object of the present invention is to realise a well- integrated packaging laminate possessing superior oxygen gas barrier properties as well as superior aroma barrier properties at a lower cost.
• Still a further object of the present invention is to realise a well- integrated packaging laminate possessing superior oxygen gas barrier properties also in environments of high relative humidity.
• One particular object of the present invention is to realise a well- integrated packaging laminate possessing superior oxygen gas barrier properties and, compared with the prior art technology, at least equivalent mechanical properties such as strength and flexibility, at a lower cost.
• a further object of the present invention is to realise a simple, rational method of producing, with existing process equipment and at lower cost, a packaging laminate possessing superior oxygen gas barrier properties and also superior aroma barrier properties and, compared with the prior art technology, at least equivalent mechanical properties.
• the method of producing the packaging laminate according to the present invention has the characterizing features as set forth in appended Claims 17 and 18, respectively.
• the core layer in the packaging laminate according to the invention consists of a fibre material such as, for example, paper or paperboard of a suitable packaging quality.
• the plastic layer which constitutes the gas barrier layer in the packaging laminate according to the invention includes a so-called aliphatic polyketone, i.e. a linear copolymer with perfectly alternating carbon monoxide and olefin monomer.
• the term "perfectly alternating” is here taken to signify that carbon monoxide monomers and olefin monomers respectively essentially constitute every second linear building block in the polymer chains so that the polymer molecules include roughly 50 mol per cent of each of carbon monoxide and ⁇ -olefin.
• Such polymers are semi- crystalline thermoplastic materials with high molecular weight.
• the linear copolymer is a perfect 100 per cent alternating copolymer of carbon monoxide and ethylene, and, where applicable, may encompass a minor quantity of additionally one or more randomly copolymerised ⁇ - olefins with at least 3 carbon atoms.
• Suitable additional copolymerised ⁇ - olefins have 3-12 carbon atoms, preferably 3-6 carbon atoms, such as, for example, propylene 1-butene or isobutene.
• Such aliphatic polyketones are distinguished not only from randomly alternating copolymers of ethylene and carbon monoxide which are produced by means of free radical polymerisation and contain a considerably lower proportion of carbon monoxide than 50 mol per cent, but also from aromatic polyketones, for example polyether ketones.
• the aliphatic polyketone in a gas barrier layer in a packaging laminate according to the present invention is such a tercopolymer of carbon monoxide, ethylene and a minor quantity of ⁇ -olefin with at least 3 carbon atoms such as, for example, propylene and may be represented by the repeating unit
• the terpolymer contains up to approx. 15 weight per cent, preferably approx. 1-10 weight per cent of ⁇ -olefin, preferably propylene.
• the aliphatic polyketone in a gas barrier layer in the packaging laminate according to the present invention preferably has a molecular weight (number average) which lies between approx. 1,000 and approx. 250,000, more preferably between approx. 20,000 and approx. 150,000, a melting point from about 175 to about 300°C and a melt index of between 5 and 2,000 g/ 10 min., at 5 kg and 240°C.
• a glass transition temperature Tg of between 10 and 15°C and a density of approx. 1.22-1.24.
• Such aliphatic polyketones have, in addition to excellent gas barrier properties and aroma barrier properties, also good mechanical properties, good chemical resistance, good heat resistance and also good processing properties, making it suitable for gas and aroma barrier materials in packages for foods. Moreover, it may be produced at a low cost in relation to other prior art polymer gas barrier materials.
• the gas barrier layer consists, according to one embodiment of the present invention, substantially of the above-described aliphatic polyketone, but may also contain a mixture of this polyketone and a second thermoplastic such as, for example, a polyolefin.
• a second thermoplastic such as, for example, a polyolefin.
• the mixing ratio between the aliphatic polyketone and the second thermoplastic polymer may suitably vary between 1:99 and 99:1.
• the mixture contains approx. 30-70 weight per cent polyketone and, most preferably approx. 40-60 weight per cent of polyketone.
• the mixture may be such that the aliphatic polyketone forms a dispersed phase in a matrix of the second thermoplastic polymer, in the form of multiple, thin, substantially parallel and overlapping layers, a so-called laminar blend.
• laminar blends of, for example, EVOH and polyolefin are known by persons skilled in this art, see for example W096/ 10053, and are produced by means of attenuation of the dispersed phase in the polymer melt during the extrusion process.
• the packaging laminate according to the invention may also include outer layers of a heat-sealable polymer on one or both sides, normally polyethylene of a suitable quality, for example low density polyethylene (LDPE).
• LDPE low density polyethylene
• Other heat-sealable plastics known to persons skilled in this art may also advantageously be provided as outer layers in the packaging laminate according to the present invention.
• the adhesion between the polyketone-containing gas barrier layer and adjacent layers may be further improved by means of an interjacent layer of an adhesive polymer such as, for example, a copolymer of olefin and (meth)acrylic acid, acid- or anhydride-modified polyolefin or a so-called ionomer.
• an adhesive polymer such as, for example, a copolymer of olefin and (meth)acrylic acid, acid- or anhydride-modified polyolefin or a so-called ionomer.
• the adhesion between the polyketone layer and adjacent layers may be improved by a surface active pre-treatment by means of, for example, flash treatment techniques or corona and / or plasma techniques, in which event lamination of the polyketone layer to the remainder of the packaging laminate may be put into effect by means of film lamination of prefabricated film and/ or semi-manufactured packaging laminate.
• Fig. 1 schematically illustrates a cross section through a laminated packaging material 10a and 10b, respectively, according to the present i vention
• Fig. 2 schematically illustrates a cross section through a laminated packaging material 20a and 20b, respectively, according to the present invention.
• Fig. 3 schematically illustrates a cross section through a laminated packaging material 30a and 30b, respectively, according to the present invention.
• Fig. 1 thus schematically illustrates a cross section of a packaging laminate according to the present invention, carrying the generic reference numerals 10a and 10b, respectively.
• the packaging laminate 10a comprises a core layer 11 of paper or paperboard of suitable packaging quality, and, directly applied on the one side of the core layer corresponding to the inside of the packaging container produced from the packaging laminate, a gas barrier layer 12 of a perfectly alternating linear copolymer of carbon monoxide and ethylene, with up to approx. 15 weight per cent propylene monomer randomly copolymerised and incorporated into the polymer structure instead of ethylene monomer.
• the core layer On its opposite side corresponding to the outside of the packaging container produced from the packaging laminate, the core layer is coated with a liquid-tight plastic layer 13 of, for example, LDPE.
• the gas barrier layer 12 is disposed on the core layer 11, for example by means of direct extrusion coating. In a packaging container produced from the packaging laminate 10a, the gas barrier layer 12 is thus in direct contact with the packed product.
• the packaging laminate 10b moreover includes an inside layer 13' consisting of one or more part layers, of a liquid-tight, heat-sealable plastic such as, preferably, polyethylene of a well-functioning quality (for example LDPE).
• a liquid-tight, heat-sealable plastic such as, preferably, polyethylene of a well-functioning quality (for example LDPE).
• the adhesion between the gas barrier layer 12 and the inside layer 13' is improved by means of an interjacent adhesion layer 14, a so-called "tie-layer", of an adhesion-promoting polymer.
• the inside layer 13' and the tie layer 14 are applied, for example, by co-extrusion. Fig.
• FIG. 2 shows an alternative packaging laminate 20a, 20b, respectively in which the core layer 21, the gas barrier layer 22 and the outer layer 23 are of the same type as layers 11, 12 and 13, respectively, in Fig. 1, but in which the gas barrier layer 22 is bonded to the core layer 21 by means of an interjacent adhesion layer 24 of an adhesive polymer.
• the interjacent adhesive layer functions, on the one hand, as an adhesion-promoting layer and, on the other hand, as a smoothening layer for the coarse, rough paper surface of the core layer, whereby the quantity of applied polyketone in the gas barrier layer 22 may be reduced while retaining oxygen gas and aroma barrier effects.
• the adhesion layer 24 and the gas barrier layer 22 are applied, for example, by means of co-extrusion onto the core layer 21.
• the packaging laminate 20b moreover includes an inside layer 23' consisting of one or more part layers of a liquid-tight, heat-sealable plastic such as, preferably, polyethylene of a well-functioning quality (for example LDPE), and an interjacent adhesion layer 25.
• a liquid-tight, heat-sealable plastic such as, preferably, polyethylene of a well-functioning quality (for example LDPE)
• the four layers 24, 22, 25 and 23' may be applied simultaneously by co-extrusion or as separate or partly co-extruded layers.
• Fig. 3 shows a packaging laminate 30a, 30b, respectively in which the core layer 31, the gas barrier layer 32 and the outer layer 33 are of the same type as layers 11, 12 and 13, respectively, in Fig.
• thermoplastic layer 34 such as, for example, polyethylene
• adhesion layer 35 of an adhesive polymer provided between the thermoplastic layer 34 and the gas barrier layer 32.
• the thermoplastic layer 34, the adhesion layer 35 and the gas barrier layer 32 are coated, for example, by means of co- extrusion onto the core layer 31.
• the packaging laminate 30b moreover includes an inside layer 33' consisting of one or more part layers of a liquid-tight, heat-sealable plastic such as, preferably, polyethylene of a well-functioning quality (for example LDPE), and an interjacent adhesion layer 36.
• a liquid-tight, heat-sealable plastic such as, preferably, polyethylene of a well-functioning quality (for example LDPE)
• interjacent adhesion layer 36 for example LDPE
• the five layers 34, 35, 32, 36 and 33' may be applied simultaneously by co-extrusion or as separate or partly co-extruded layers.
• gas barrier layer 12; 22; 32 may alternatively be incorporated into the packaging laminate structure by means of film lamination of the gas barrier layer alone or in combination with one or more adhesive layers and/ or lamination layers of thermoplastic, even though extrusion or co-extrusion is the most preferred method of applying the gas barrier layer.
• the present invention in a simple manner and with simple means, at lower cost, attains the established objects and realises an efficient, well-integrated laminate packaging material possessing both superior oxygen gas and aroma barrier properties and also at least retained mechanical properties such as strength and flexibility, as well as heat resistance.

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• Laminated Bodies (AREA)
• Wrappers (AREA)
• Polyethers (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

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• 1997
  • 1997-02-03 SE SE9700317A patent/SE514836C2/sv not_active IP Right Cessation
• 1998
  • 1998-02-02 JP JP53279298A patent/JP2001509748A/ja not_active Ceased
  • 1998-02-02 EP EP98902347A patent/EP0956197A1/de not_active Withdrawn
  • 1998-02-02 AU AU58901/98A patent/AU5890198A/en not_active Abandoned
  • 1998-02-02 WO PCT/SE1998/000150 patent/WO1998033647A1/en not_active Application Discontinuation
  • 1998-02-02 BR BR9807150-5A patent/BR9807150A/pt not_active Application Discontinuation

Non-Patent Citations (1)

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