Packaging material and packaging container

Abstract

Described herein are laminated packaging materials comprising foamed cellulose, their use in manufacturing packaging containers, for use in packaging of food products.

Claims

1. A packaging material for a packaging container for liquid or semi-liquid food, the packaging material comprising a decor layer, a bulk layer on one side of the decor layer, a barrier layer on a side of the bulk layer opposite the decor layer, and a heat-sealable layer on a side of the barrier layer opposite the bulk layer so that the bulk layer is positioned between the decor layer and the barrier layer while the barrier layer is positioned between the bulk layer and the heat-sealable layer, the bulk layer having a density of at least 100 kg/m.sup.3 and less than 700 kg/m.sup.3 and being comprised of crosslinked foamed fibrous cellulose of at least 25% thickness of the bulk layer.

2. The packaging material according to claim 1, wherein the packaging material has a delamination strength of 120-300 J/m.sup.2 as determined in accordance with TAPPI T569.

3. A packaging container manufactured from a packaging material according to claim 1, wherein the packaging container is a container for liquid or semi-liquid food product.

4. The packaging container according to claim 3, wherein the packaging container is a brick shaped packaging container, a gable top packaging container, a wedged-shape packaging container, a square-, rectangular- or octagonal-based packaging container, or a pouch.

5. The packaging material according to claim 1, wherein the bulk layer has a density from 300 kg/m.sup.3 to 500 kg/m.sup.3.

6. The packaging material according to claim 1, wherein the bulk layer has a density from 100 kg/m.sup.3 to 600 kg/m.sup.3.

7. The packaging material according to claim 1, wherein the fibrous cellulose is selected from the group consisting of chemical pulp fibers, chemi-thermomechanical pulp fibers, thermo-mechanical pulp fibers, and Kraft pulp fibers.

Description

DESCRIPTION OF THE DRAWINGS

(1) Further advantages and favorable characterizing features will be apparent from the following detailed description, with reference to the appended figures, in which:

(2) FIGS. 1a and 1b are cross-sectional views of laminated packaging materials according to aspects described herein.

(3) FIGS. 2a and 2b are cross-sectional views of laminated packaging materials according to aspects described herein.

(4) FIG. 3 is a schematic drawing of an extruder, the extruded film, a paper or packaging material web and the rollers arrange to join the plastic and the bulk layer.

(5) FIG. 4 shows examples of packaging containers produced from the packaging material according to embodiments described herein.

(6) FIG. 5 shows the principle of how such packaging containers are manufactured from the packaging material in a continuous forming, filling and sealing process.

(7) FIG. 6 shows resulting thickness reductions of lamination materials comparing the original thickness before lamination and the thickness after lamination.

(8) FIG. 7 shows the influence of exposure time on the delamination strength.

(9) FIG. 8 shows the influence of amount of crosslinker material on the delamination strength.

(10) FIG. 9 shows the influence of amount of crosslinker material and exposure time on the edge wick index.

(11) FIG. 10 shows the influence of amount of crosslinker material on the edge wick index.

(12) FIG. 11 shows the influence of amount of crosslinker material on the delamination strength with and without EB.

(13) FIG. 12 shows the influence of crosslinker material on the delamination strength.

GENERAL DESCRIPTION OF EMBODIMENTS

(14) FIG. 1a schematically shows a cross-section of a packaging material. The decor layer (11) is a polyolefin such as a suitable LDPE or PP. The decor layer may for example be used to provide cover of a printed pattern, a hole and/or weakening (not shown in the figure) provided in any of the other layers. On one side of the decor layer a bulk layer (12) is arranged. On the other side of the bulk layer, opposite to the decor layer, a barrier layer (14) is arranged. Between the barrier layer and the bulk layer an optional laminate layer can be arranged if needed. Similarly one or both the layers may be surface modified or contain a coating in order to provide for sufficient adhesion between the bulk and barrier layer. The barrier layer (14) provides a desired barrier such as oxygen, light, water and vapour barrier depending on the specific need determined by the product to be packed. The barrier layer can for example be an aluminium foil or a vapour deposited film, such as a metallized or vapour deposition coated, such as PECVD coated, film. On the side opposite the bulk layer the barrier layer is arranged with a heat-sealable layer (16) such as a suitable polyolefin such as PE or PP or blends thereof. Between the barrier layer and the heat-sealable layer an adhesive may be used when needed. The heat-sealable layer is the layer facing the product in the finished packed packaging container.

(15) FIG. 1b schematically shows a cross-section of a packaging material. The decor layer (11) is a polyolefin such as a suitable LDPE or PP. The decor layer may be used to provide cover of a printed pattern, a hole and/or weakening (not shown in the figure) which is provided on the bulk layer (12), which layer is arranged on one side of the decor layer (11). The bulk layer (12), on the side opposite the decor layer, has a laminate layer (13) selected from suitable polyolefins such as LDPE or PP. The laminate layer provides adhesion to the oxygen barrier (14), which is arranged on the opposite side of the bulk layer (13). The barrier layer (14) provides the desired barrier such as oxygen, light, water and vapour barrier depending on the specific need determined by the product to be packed. The barrier layer can for example be an aluminium foil or a vapour deposited film, such as a metallized or vapour deposition coated, such as PECVD coated film. On the side opposite the laminate layer an adhesive polymer (15) is arranged on the barrier layer. The adhesive polymer (15) may for example be applied by extrusion coating. When the barrier layer is aluminium foil the adhesive could be a suitable adhesive such as an ethylene (meth)acrylic acid copolymer (E(M)AA) marketed under the tradename Primacor® or Nucrel®. On the side opposite the barrier layer, the adhesive is provided with a heat-sealable layer (16) such as a suitable polyolefin such as PE or PP or blends thereof. The heat-sealable layer is the layer facing the product in the finished packed packaging container.

(16) FIG. 2a schematically shows a cross-section of a packaging material. The decor layer (21) is a polyolefin such as a suitable LDPE or PP. The decor layer may be used to provide cover of a printed pattern, a hole and/or weakening (not shown in the figure) which is provided in the bulk layer (22), which layer is arranged on one side of the decor layer (21). Between the decor layer (21) and the bulk layer (22) an additional layer (27) of paper or cellulose is arranged. The bulk layer (22), on the side opposite the decor layer, has a laminate layer (23) selected from suitable polyolefins such as LDPE or PP. The laminate layer provides adhesion to the oxygen barrier (24), which is arranged on the opposite side of the laminate layer (23). The barrier layer (24) provides the desired barrier such as oxygen, light, water and vapour barrier depending on the specific need determined by the product to be packed. The barrier layer can for example be an aluminium foil or a vapour deposited film, such as a metallized or vapour deposition coated film, such as a PECVD (plasma enhanced chemical vapour deposition) coated film. On the side opposite the laminate layer an adhesive polymer (25) is arranged on the barrier layer. The adhesive (25) may for example be applied by extrusion coating. When the barrier layer is aluminium foil the adhesive could be a suitable ethylene (meth)acrylic acid copolymer (E(M)AA) adhesive marketed under the tradename Primacor® or Nucrel®. On the side opposite the barrier layer, the adhesive is provided with a heat-sealable layer (26) such as a suitable polyolefin such as PE or PP or blends thereof. The heat-sealable layer is the layer facing the product in the finished packed packaging container.

(17) FIG. 2b schematically shows a cross-section of a packaging material. The decor layer (21) is a polyolefin such as a suitable LDPE or PP. The decor layer may be used to provide cover for a printed pattern, a hole and/or weakening (not shown in the figure) which is provided in one or more of the other layers of the laminate. On one side of and adjacent the decor layer, a thin paper (27) of a surface weight of about 100 g/m.sup.2 or lower is arranged. The thin paper layer (27) is laminated to a bulk layer (22), opposite the decor layer, by an intermediate thermoplastic outer binding layer (28). The binding layer (28) may be selected from suitable polyolefins such as LDPE or PP or blends thereof. The binding layer (28) binds the bulk cellulose layer (22) and the thin paper layer (28) together. The bulk layer (22), is further laminated to a laminate layer (23) of thermoplastic polymer, on the side of the bulk layer opposite the side laminated to the binding layer (28). The laminate layer (23) provides adhesion to an oxygen barrier layer (24), which is arranged on the opposite side of the laminate layer (23). The barrier layer (24) provides the desired barrier such as oxygen, light, water and vapour barrier depending on the specific need determined by the product to be packed. The barrier layer can for example be an aluminium foil or a vapour deposited film, such as a metallized or vapour deposition coated film, such as a PECVD coated film. On the side opposite the laminate layer an adhesive polymer (25) is arranged on the barrier layer. The adhesive (25) may for example be applied by extrusion coating. When the barrier layer is aluminium foil the adhesive could be a suitable ethylene (meth)acrylic acid copolymer (E(M)AA) adhesive marketed under the tradename Primacor® or Nucrel®. On the side opposite the barrier layer, the adhesive is provided with a heat-sealable layer (26) such as a suitable polyolefin such as PE or PP or blends thereof. The heat-sealable layer is the layer facing the product in the finished packed packaging container. FIG. 3 is a schematic illustration of an extruder (31). An extruder of the schematic illustration is suitable for application of the, decor layer (11), laminate layer (13), adhesive (15) and the heat-sealable layer (16). As an example the laminate layer (13) can be applied on the bulk layer (12), whereby the drawing shows a molten plastic film (32) of the polymer to become the laminate layer (13) being arranged by melt extrusion coating onto a bulk layer web (35). The extruder melts and mixes the polymer(s). In case of the layers being polymer blends, the extruder may also be used to blend the polymers which are for example supplied via separate hoppers for the polymer granules. The molten film (32) and the bulk layer are joined in a lamination nip between rollers (33 and 34) which exert a pressure. One of the rollers can be a chilled roller which reduces the temperature of the polymer when in the nip. Similarly the other polymers of the packaging material may be added to the bulk layer (35). The barrier layer (14) may for example be forwarded from a separate roll and fed through the lamination nip together with the laminate layer (13), or with an adhesive.

(18) FIG. 4 shows an example of a packaging container 50a produced from the packaging material described in FIG. 1 or 2. The packaging container is particularly suitable for liquid or semi-liquid food products such as beverages, sauces, soups or the like. Typically, such a package has a volume of from about 100 to about 2000 ml. It may be of any configuration such as those previously described herein, but is for example brick-shaped, having longitudinal and transversal seals 51a and 52a, respectively, and optionally an opening device 53. In another embodiment, not shown, the packaging container may be shaped as a wedge. In order to obtain such a “wedge-shape”, only the bottom part of the package is fold formed such that the transversal heat-seal of the bottom is hidden under the triangular corner flaps, which are folded and sealed against the bottom of the package. The top section transversal seal is left unfolded. In this way the half-folded packaging container is still easy to handle and dimensionally stable (i.e. substantially maintains form and shape) when put on a shelf in the food store or on a table or the like.

(19) FIG. 5 shows the principle as described in the introduction of the present application, i.e. a web of packaging material is formed into a tube 71 by the longitudinal edges 72, 72′ of the web being united to one another in an overlap heat-sealed joint 73. The tube is filled 74 with the intended liquid food product and is divided into individual packages by repeated transversal seals 75 of the tube at a pre-determined distance from one another below the level of the filled contents in the tube.

(20) The packages 76 are separated by incisions in the transversal seals and are given the desired geometric configuration by fold formation along prepared crease lines in the material.

(21) The invention is not limited by the embodiments shown and described above, but may be varied within the scope of the claims. Modifications and alterations, obvious to a person skilled in the art, are possible without departing from the concept as disclosed in the appended claims.

Embodiments

(22) A packaging material for a packaging container for liquid or semi-liquid food, comprising a decor layer (11) which on one side of the layer has a bulk layer (12) having a density of less than 700 kg/m.sup.3 and crosslinked foamed cellulose of at least 25% thickness of the bulk layer, which on the side opposite the decor layer (11) has a barrier layer (14), which on the side opposite the bulk layer (12) has a heat-sealable layer (16).

(23) The packaging material comprising an adhesive between the heat-sealable layer and the barrier layer.

(24) The packaging material comprising a laminate layer between the bulk layer and the barrier layer.

(25) The packaging material comprising an additional layer between the decor layer and the bulk layer.

(26) The packaging material, wherein the additional layer is a paper or paperboard layer or an oriented polymer film.

(27) The packaging material, wherein the additional layer is a paper layer having a grammage of at least 20 g/m.sup.2. The packaging material comprising a binding layer between the additional layer and the bulk layer.

(28) The packaging material wherein the bulk layer has a density from 100 to 600 kg/m.sup.3, such as from 100 to 500 kg/m.sup.3, such as from 200 to 500 kg/m.sup.3, such as from 300 to 500 kg/m.sup.3, such as from 300 to 400 kg/m.sup.3.

(29) The packaging material, wherein the bulk layer has a surface weight grammage of at least 20 g/m.sup.2, such as at least 60 g/m.sup.2, such as between 60 and 250 g/m.sup.2.

(30) The packaging material, wherein the decor layer is selected from heat-sealable polyolefin layer(s) selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), ultra low-density polyethylene (ULDPE) or LLDPE manufactured by using metallocene catalysts (mLLDPE) and blends of two or more thereof; high density polyethylene (HDPE); polypropylene or propylene co- or ter-polymers.

(31) The packaging material, wherein the laminate layer and the heat-sealable layer are individually selected from the group consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), ultra low-density polyethylene (ULDPE) or LLDPE manufactured by using metallocene catalysts (mLLDPE) and blends thereof; and polypropylene or propylene co- or ter-polymers.

(32) The packaging material, wherein the oxygen barrier is selected from the group consisting of aluminium foil and vapour deposition coated film, such as metallized or chemical vapour deposition coated film.

(33) The packaging material, wherein the packaging material has a delamination strength of 120-300 J/m.sup.2 as determined in accordance with TAPPI T569.

(34) A packaging container manufactured from a packaging material according to the present invention, wherein the packaging container is a container for liquid or semi-liquid food product.

(35) The packaging container, wherein the packaging container is a brick shaped packaging container, a gable top packaging container, a wedged-shape packaging container, a square-, rectangular- or octagonal-based packaging container, or a pouch.

(36) A method of providing a packaging material for a packaging container for liquid or semi-liquid food, wherein the method comprises providing foamed cellulose; crosslinking the foamed cellulose by a) contacting with a crosslinking mixture comprising a polymeric and/or monomeric material and optionally a photoinitiator, and/or b) at least partially functionalising the foamed cellulose and optionally providing a photoinitiator, and subjecting to radiation to provide a crosslinked foamed cellulose; providing a bulk layer having a density of less than 700 kg/m.sup.3 and comprising the crosslinked foamed cellulose; providing a polyolefin decor layer on one side of the bulk layer; providing a barrier layer on the side opposite the decor layer; providing a heat-sealable layer on the barrier layer, on the side opposite the bulk layer; and wherein the packaging material is obtained by extrusion lamination and/or heat-pressure lamination.

(37) The method additionally comprising a step of providing an adhesive between the heat-sealable layer and the barrier layer.

(38) The method additionally comprising a step of providing a laminate layer between the bulk layer and the barrier layer.

(39) The method additionally comprising a step of providing an additional layer between the decor layer and the bulk layer.

(40) The method wherein the additional layer is a paper or paperboard layer or an oriented polymer film.

(41) The method wherein the additional layer is a paper layer having a grammage of at least 20 g/m.sup.2.

(42) The method additionally comprising a step of providing a binding layer between the additional layer and the bulk layer.

(43) The method, wherein the bulk layer has a density from 100 to 600 kg/m.sup.3, such as from 100 to 500 kg/m.sup.3, such as from 200 to 500 kg/m.sup.3, such as from 300 to 500 kg/m.sup.3, such as from 300 to 400 kg/m.sup.3.

(44) The method, wherein the bulk layer has a surface weight grammage of at least 20 g/m.sup.2, such as at least 60 g/m.sup.2, such as between 60 and 250 g/m.sup.2.