CA2730779C

CA2730779C - Laminate for a bag for flowable material having an oriented polypropylene, and a bag made therefrom

Info

Publication number: CA2730779C
Application number: CA2730779A
Authority: CA
Inventors: David Bellmore; Karen Berger
Original assignee: Scholle Corp
Current assignee: Scholle IPN Corp
Priority date: 2008-07-15
Filing date: 2009-07-15
Publication date: 2015-11-24
Anticipated expiration: 2029-07-15
Also published as: AU2009271582A1; WO2010008557A3; AU2009271582B2; CA2730779A1; EP2323913A2; US20100129008A1; NZ590589A; WO2010008557A2; EP2323913A4; BRPI0911001A2

Abstract

A bag for a flowable material comprising a plurality of walls coupled together by way of a plurality of seals to define a substantially fluid tight cavity. The plurality of walls each comprising a laminate structure comprising a sealant layer of a polyethylene material, a core layer of an oriented polypropylene material, and a cap layer of an EVOH material.

Description

LAMINATE FOR A BAG FOR FLOWABLE MATERIAL HAVING AN ORIENTED
POLYPROPYLENE, AND A BAG MADE THEREFROM
[0000]
BACKGROUND OF THE DISCLOSURE
[0001] 1. Field of the Disclosure

[0002] The disclosure relates in general to bags, and more particularly, to a laminate for a bag for flowable material having an oriented polypropylene.

[0003] 2. Background Art

[0004] The use of bags for flowable material, such as liquids and syrups (among others), is known in the art. For example, wines are packaged in such bags which are then inserted into boxes (commonly termed bag-in-box wine packaging). A constant struggle with such packaging is to limit bag cracking that typically occurs during shipping and transport. Additionally, with certain products, it is necessary to limit the quantity of oxygen that is transmitted through the bag (typically quite significant for wine products).

[0005] One structure that is utilized comprises a three layer laminate comprising an EVOH cap layer, a BON core layer and a PE sealant layer. While this structure has been utilized, there is a need to provide a structure that has a material which has less susceptibility to flex cracking and which has a lower oxygen transmission rate.

[0006] It is an object of the present invention to improve the performance of bag

7 laminate constructions.
[0007] It is another object of the present invention to improve resistance to flex cracking in laminate constructions for bags.

[0008] It is another object of the invention to reduce the oxygen transmission rate in laminate constructions for bags.

[0009] These objects as well as other objects of the present invention will become apparent in light of the present specification, claims, and drawings.

SUMMARY OF THE DISCLOSURE

[0010] The disclosure is directed to a bag for a flowable material comprising a plurality of walls coupled together by way of a plurality of seals to define a substantially fluid tight cavity. The plurality of walls each comprising a laminate structure comprising a sealant layer comprising a polyethylene material; a core layer comprising an oriented polypropylene material; and a cap layer comprising an EVOH material.

[0011] In a preferred embodiment, at least one of the layers further includes a metallized vapor deposited layer thereon.

[0012] In another preferred embodiment, the metallized vapor deposited layer is deposited on a side of the core layer.

[0013] In yet another preferred embodiment, the metallized vapor deposited layer comprises aluminum.

[0014] In another preferred embodiment, the metallized vapor deposited layer comprises one of the group consisting of: metals, PVDC, aluminum oxide and silicon oxide.

[0015] Preferably, the sealant layer further comprises: 1.8 mil thick 0.920 g/cc octene LLDPE (1.0g/10 min MI).

[0016] In another embodiment, the core layer further comprises 0.70 mil thick oriented polypropylene material.

[0017] In yet another preferred embodiment, the core layer further includes a treatment applied thereto, wherein the treatment is selected from the group consisting of:
plain, corona, plasma and chemical.

[0018] Advantageously, the cap layer may comprise a multi-sub-layer EVOH

based layer.

[0019] In another preferred embodiment, the base of the EVOH layer comprises a propylene sub-layer.

[0020] In one such preferred embodiment, the EVOH layer includes a plurality of polyethylene sub-layers sandwiched around an EVOH sub-layer.

[0021] In another such embodiment, the EVOH layer comprises a plurality of sub-layers including, at least one vinyl acetate sub-layer, a plurality of polyethylene sub-layers and an EVOH sub-layer surrounded by the plurality of polyethylene sub-layers.

[0022] In one such embodiment, the EVOH layer comprises five sub-layers, including, in order, a first linear low density polyethylene sub-layer, a second linear low density polyethylene sub-layer, a third linear low density polyethylene sub-layer, an EVOH sub-layer, and a forth linear low density polyethylene sub-layer.

[0023] Preferably, the first linear low density sub-layer comprises a 0.55 mil 50%
12%VA (0.40 g/10 min MI)/ 50% 0.920 g/cc octene LLDPE (1.0g/10 mm MI) with anti-block, anti-oxidant, and slip additives.

[0024] Preferably, the second linear low density sub-layers comprise a 0.20 mil 100% 0.924 g/cc anhydride modified LLDPE (2.2 g/10 min MI).

[0025] Preferably, the third linear low density sub-layer comprises a 0.30 mil 29 mol% ethylene EVOH (3.8g/10 MM MI).

[0026] Preferably, the EVOH sub-layer comprises a 0.20 mil 100% 0.924 g/cc anhydride modified LLDPE (2.2 g/10 min MI).

[0027] Preferably, the fourth linear low density sub-layer comprises a 0.55 mil 100% 0.920 g/cc octane LLDPE (1.0g/10 min MI) with anti-block, anti-oxidant, and slip additives.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The disclosure will now be described with reference to the drawings wherein:

[0029] Figure 1 of the drawings is a top plan view of a bag having the laminate construction of the present invention; and

[0030] Figure 2 of the drawings is a cross-sectional view of the laminate construction of the present invention.

DETAILED DESCRIPTION OF THE DISCLOSURE .

[0031] While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and described herein in detail a specific embodiment with the understanding that the present disclosure is to be considered as an exemplification and is not intended to be limited to the embodiment illustrated.

[0032] It will be understood that like or analogous elements and/or components, referred to herein, may be identified throughout the drawings by like reference characters.
In addition, it will be understood that the drawings are merely schematic representations of the invention, and some of the components may have been distorted from actual scale for purposes of pictorial clarity.

[0033] Referring now to the drawings and in particular to Figure 1, a bag having a laminate structure 10 is shown. The bag comprises a conventional bag for flowable material (such as syrup, wine, fine powders, and the like). In the embodiment shown, a pillow type bag is shown which includes a plurality of walls 20, 22 and a plurality of seals, such as seal 24 which joins the walls to each other to define cavity 25.
In certain embodiments, a spout, such as spout 26 is disposed on one of the walls to provide fluid communication to the cavity. Typical sizes for such pillow type containers often range between 1 liter and 20 liters. Of course, this is not deemed as limiting the bag to a particular size, but, rather, is provided as exemplary of conventional sizes of such containers.

[0034] Of course, in other embodiments, a alternate bag construction can be utilized. For example, the laminate structure 10 can be used in association with other bag constructions, such as gusseted bags or bags that are formed from a number of different constructions with a number of different seals formed in any one of a number of different formats. In other words, the laminate is shown in an exemplary embodiment with the understanding that there is no limitation as to the configuration and structure of the bag with which the laminate is utilized.

[0035] With specific reference to the laminate structure, and as is shown in Figure 2, the laminate structure comprises a sealant layer 30, a core layer 32 and a cap layer 34.
The three layers are laminated together. In one embodiment, it is contemplated that the three layers are adhered to each other. For example, a two component solventless polyurethane adhesive system 41, 43 can be utilized between the layers. In other embodiments, the three layers may be thermally bonded together. Indeed, the particular manner in which the three layers are coupled together to form a laminate can be another mechanism altogether without departing from the scope of the invention.

[0036] In a preferred embodiment, the sealant layer (which comprises the product contact layer) comprises a polyethylene material. For example, in one specific embodiment, the material comprises a 1.8 mil thick 0.920 g/cc octene LLDPE
(1.0g/10 min MI) with anti-block, anti-oxidant and slip additives. Of course other polyethylene materials are contemplated for use as well. For example, a propylene based sealant layer can be utilized (homopolymer, impact copolymer, random copolymer or elastomer/plastomer). In certain embodiments, such a propylene based sealant layer can aid adhesion during thermal lamination processes.

[0037] The core layer 32 comprises an oriented polypropylene film (OPP).
In one embodiment, 0.70 mil thick corona treatment/oriented polypropylene/heat sealable layer material is contemplated. In another embodiment, this layer may be metalized such that the structure may include a 2.1 minimum optical density aluminum layer. One manner of applying such a metallized layer comprises the use of metal vapor deposition on the film.
Of course, other configurations of oriented polypropylene films are likewise contemplated for use.

[0038] It is contemplated that a number of different thicknesses can be utilized.
Additionally, a number of treatments may be applied (plain, corona, plasma and chemical). Further, heat sealable layers can be added on either side of the OPP, or on both sides. Finally, other coatings can be added, in addition to aluminum, such as other metals, PVDC, aluminum oxide and silicon oxide. Additionally, the optical density can be varied as desired.

[0039] With continued reference to Figure 2, the cap layer 34 comprises a EVOH
material. In the embodiment shown, a five sub-layer co-extruded EVOH based layer is contemplated. The five sub-layers 51-55 comprise: (1) 0.55 mil 50% 12%VA (0.40 g/10 min MI)/ 50% 0.920 g/cc octene LLDPE (1.0g/10 min MI) with anti-block, anti-oxidant, and slip additives; (2) 0.20 mil 100% 0.924 g/cc anhydride modified LLDPE (2.2 g/10 min MI); (3) 0.30 mil 29 mol% ethylene EVOH (3.8g/10 Min MI); (4) 0.20 mil 100%
0.924 g/cc anhydride modified LLDPE (2.2 g/10 min MI); and (5) 0.55 mil 100%
0.920 g/cc octane LLDPE (1.0g/10 min MI) with anti-block, anti-oxidant, and slip additives. Of course, other polyethylene layers are likewise contemplated for use. A
propylene based cap layer can be utilized (homopolymer, impact copolymer, random copolymer or elastomer/plastomer). In certain embodiments, such a propylene based cap layer can aid adhesion during thermal lamination. More specifically, this would be applicable to just OPP (not MOPP) and the propylene based material would be added to layer 55 (Figure 2).
' [0040] Advantageously, over the prior art EVOH/BON/PE material, the present disclosed embodiment has over a three-fold increase in flex crack resistance and over a two-fold improvement in oxygen transmission rate. As the OPP material has a lower modulus than the prior used BON, the thickness of this layer can be increased without affecting the bag modulus.
[0041] The foregoing description merely explains and illustrates the invention by means of preferred embodiments. The scope of the claims should not be limited by the preferred embodiments set forth in the description, but should be given the broadest interpretation consistent with the description as a whole.
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Claims

WHAT IS CLAIMED IS:

1. A bag for a flowable material, for use in bag in box packaging, comprising:
i) a plurality of walls coupled together by way of a plurality of seals to define a substantially fluid tight cavity, the plurality of walls each comprising a laminate structure comprising:
a) a sealant layer comprising a polyethylene film having a first side and a second side;
b) a core layer comprising an oriented polypropylene material, the core layer having a first side and a second side, with the first side of the sealant layer directly laminated through thermal lamination or adhesive lamination to the first side of the core layer; and c) a cap layer comprising a coextruded film having an EVOH layer surrounded on both sides by a polyethylene layer, the cap layer having a first side and a second side, the second side of the cap layer directly laminated through thermal lamination or adhesive lamination to the second side of the core layer, wherein the cap layer is the outermost layer of the formed bag and the sealant layer is the innermost layer of the formed bag.

2. The bag for a flowable material of claim 1 wherein one of the first surface and the second surface of the core layer includes a metallized layer.

3. The bag for a flowable material of claim 2 wherein the metallized layer comprises a vapor deposited aluminum metallized layer having an optical density of at least 2.1.

4. The bag for a flowable material of claim 2 wherein the metallized layer comprises one member selected from the group consisting of metals, aluminum oxide and silicon oxide.

5. The bag for a flowable material of claim 1 wherein the sealant layer is 1.8 mil thick, the core layer is 0.7 mil thick and the cap layer is 1.8 mil thick.

6. The bag for a flowable material of claim 1 wherein the core layer further includes a treatment applied thereto, wherein the treatment is selected from the group consisting of: plain, corona, plasma and chemical.

7. The bag for a flowable material of claim 1 wherein the cap layer comprises a 0.30 mil 29 mol% ethylene EVOH (3.8g/10 Min MI).