CA2776225A1 - Bag - Google Patents

Abstract

A collapsible bag is provided for receiving and discharging fluids, pastes, or gases, and comprises at least one composite film with a rough internal layer (5).

Description

TERGAU & WALKENHORST Page 1 Patent Attorneys Description Bag The invention relates to a bag which is intended to receive and discharge matter. In particular, the invention relates to collapsible, flexible bags which are suitable for receiving, in general terms, matter.

Definitions In the present invention, a bag means, in general terms, a hollow, deformable item which is suitable for receiving and discharging matter. A bag can have one or more apertures through which material can be charged thereto and emptied therefrom, and these apertures can be capable of closure, for example by faucets, spouts or hose connections. Removal can also be achieved here through attached hoses. However, a bag does not have to possess apertures, an example being vacuum-packed almonds welded in a bag, or deep-frozen fish welded in a bag, or adhesive welded in a bag. Vacuum packaging is therefore a specific use of bags.

In the present invention, matter means, in general terms, objects which are observable in the natural world and which have a rest mass, can be present in macroscopic quantities, can be described quantitatively with the aid of measurable physical variables, occupy a defined space, and manifest themselves in various physical states. Matter here can comprise pure substances or substance mixtures in identical or different physical states in the form of solids, pastes, or in general terms fluids or gases, or else a mixture thereof, an example being perishable ointment under argon as inert gas. The term matter includes foods and other consumable items, such as chocolate, nuts, porridge, carbonated and other drinks, juices, TERGAU & WALKENHORST Page 2 Patent Attorneys milk, syrups, mustard, ketchup, mayonnaise, or the like.

In the present invention, a plastic or polymer is a solid of which the main constituent has been produced synthetically or semisynthetically from organic molecule units in the form of monomers via polymerization to give long-chain branched molecules.
The monomers here take the form of covalently linked repeating structural segments. In the present invention, a copolymer is a specific type of polymer produced via polymerization of a mixture of two or more chemically different monomers, and a copolymer is therefore composed of a plurality of different covalently linked monomers. In the present invention, a branched polymer is a specific type of this polymer in which molecular chains have been linked to one another in the manner of a network by way of a plurality of identical or different molecular segments. In the present invention, ionomers are thermoplastics produced via copolymerization of a nonpolar monomer with a polar monomer. The polar structural segments here suppress crystallization and give thermally reversible crosslinking. Examples of polymers to which the invention relates are polyvinyl chloride (PVC), silicones, polyesters, such as polyethylene terephthalate (PET), polyamides (PA), thermoplastic polyolefin (POP), polypropylene (PP), polyethylene (PE), and also various types of PE, such as PE having highly branched polymer chains and having low density (LDPE), PE having short highly branched polymer chains with low density from 0.915 g/cm3 to 0.935 g/cm3 (LLDPE), PE which is produced with metallocene catalysts (mLLDPE), PE having slightly branched polymer chains in the density range from 0.87 to 0.915 g/cm3 (VLDPE, ULDPE), PE having slightly branched polymer chains in the density range from 0.94 g/cm3 to 0.97 g/cm3 (HDPE), PE with moderate density from 0.926 TERGAU & WALKENHORST Page 3 Patent Attorneys to 0.940 (MDPE), and PE having ultrahigh-molecular-weight polymer chains with average molar mass up to 6000 kg/mol in the density range from 0.93 g/cm3 to 0.94 g/cm3 (UHMWPE). Examples of copolymers of ethylene to which the invention relates are ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), ethylene-acrylic acid (EAA), ethylene-methacrylate (EMA), and ethylene-methacrylic acid (EMAA).

In the present invention, a composite material is a material made of two or more materials bonded coherently and/or interlock-bonded. The properties of the composite material differ from those of its individual components. The properties of the composite materials are significantly affected by the properties of the materials of the components and by the geometry of the components. Dimensional effects are in particular significant. The components of a composite material here can themselves in turn be composite materials. Components of a composite material can by way of example be polymers coherently bonded or interlock-bonded to one another in the form of a single- or multilayer system. Laminated plastics or polymers are a specific type of composite materials which have been coherently bonded or interlock-bonded to materials other than polymers.

In the present invention, a material which is suitable for contact with foods means a material which when it has long lasting contact with foods or other consumable items does not adversely affect the nature, quality, and edibility of these, and in particular in this situation does not decompose to give other substances, in particular substances which are hazardous to health or indeed toxic.

v TERGAU & WALKENHORST Page 4 Patent Attorneys Technical Background One particular application of the bag on which the invention is based is what is known as a bag-in-box.
The bags comprising matter in liquid or paste form are within a secure surrounding pack, for example a carton, and are emptied by means of a nipple, or through faucets, spouts, or hoses or by way of discharge connections, whereupon the bag collapses into itself.

Bags of this type are usually those manufactured from plastics films or from pieces of plastics films. When the pieces of plastics films, or the plastics films, are mutually superposed, they exhibit a tendency to adhere to one another. There is therefore a tendency toward adhesion of the interior smooth film surfaces, and conventional lubricants and/or antiblocking agents cannot inhibit this tendency. Said tendency toward adhesion of the internal areas of the bag composed of film material is therefore undesirable, because a consequence of the adhesion can be formation, within the bag, of vesicles which inhibit complete emptying of the bag during discharge of its contents. Specifically when the bag contents are of very high value, complete emptying of the bag during discharge is desirable and essential. The vesicles formed by this type of adhesion equally make it difficult to achieve adequate evacuation of bags after contents have been charged thereto.

The prior art discloses bags which are composed of film material and in which an internal area of the film material has been provided with an embossment or with profiling. A disadvantage here is that the embossment or the profiling weakens the cross section of the material of the film web, with possible impairment of its strength. Furthermore, very complicated manufacturing technology is required to introduce the embossment into the film material.

TERGAU & WALKENHORST Page 5 Patent Attorneys On the basis of said disadvantages, the invention is based on the object of designing a bag in such a way that the adhesion between the internal areas is suppressed. Said object has been achieved in an inventive manner via the feature combination of claim 1. The dependent claims include embodiments of the invention which are in some cases advantageous and in some cases are themselves inventive.

In an advantageous embodiment, the bag is composed of two films or film sections, namely a region of a film with at least one rough internal side and of a congruent, opposite region, which can be composed of a smooth film which is easy to produce or of a smooth film region which is easy to produce. The rough internal side here inhibits adhesion of the two opposite film sections during collapse of the bag because, in every contact position or relative position of the two opposite internal sides of the film, a rough internal side is in contact with the opposite internal side, designed as desired, and in this sense the two sides of the film are congruent. In another embodiment, the congruent, opposite region can also have a rough internal side. Here, the rough internal side comes into direct contact with the contents. It is also possible moreover that the film has been manufactured from a flexible composite material.

Flexible plastics or polymers have proven to be particularly advantageous as film material. Polymers suitable for manufacturing the bags are only those which prove to be impermeable to the bag contents, which have high resistance to tearing and to fracture but at the same time are flexible, which are chemically inert with respect to the contents of the bag, and which feature a low purchase price. Polymers used are therefore in particular PVC, silicones, PET, PA, POP, PP, or PE, or else a mixture or copolymer thereof.

TERGAU & WALKENHORST Page 6 Patent Attorneys Among the various types of PE, those that prove especially advantageous are ULDPE, VLDPE, LLDPE, LDPE, MDPE, HDPE, EVA, EBA, EAA, EMA, and EMAA, and also ionomers, and also mixtures of the materials mentioned.
Said polymers can equally be used particularly advantageously for composite materials, in this case in the form of films, as composite films. The film for the bag here can be a single-layer film or a multilayer film in the form of composite film, and the composite film used here can either take the form of coextruded variant or else the form of laminated variant. The form in which the film has been manufactured is advantageously that of flat film, centerfolded film, or tubular film.
In another embodiment, the rough internal layer of the composite film is composed at least of one polymer and of one surface-roughening additive. The composite film can have been manufactured by blown-film extrusion or cast-film extrusion with single- or multilayer structure. However, the design of the composite film here is not restricted to two films or film sections.
Other modifications are possible during film extrusion, as also is finishing through downstream operations which vary with the subsequent design of the bag. In particular for the storage of highly perishable products, it proves particularly advantageous to apply, or incorporate, additional functional layers, for example a metallic layer as barrier layer.
A coextrusion system can be used particularly advantageously for producing the film. The film with a rough internal side can be used to produce bag- or sack-shaped packaging of a very wide variety of types, for example flat bags, flat-bottom bags, 3-edge-seal bags, bag-in-box bags, or bags made of thermoformed films.

TERGAU & WALKENHORST Page 7 Patent Attorneys A particular feature of the surface-roughening additives is that these do not melt together with the main raw materials of the film, and, after film manufacture, the particles are therefore present in the film or at least on one side of the film. Suitable surface-roughening additives are those of mineral and/or inorganic and/or organic nature, and also mixtures thereof, for example sand or clay or silica or quartz or silicic acids, or kieselguhr, or silicates or crosslinked polymers, in particular UHMWP, or other polymers whose softening point is higher than that of the actual raw material of the film. Surface-roughening additives which prove particularly successful here are those with a particle size of from 20 to 150 um, preferably those with a particle size of from 30 to 100 rim, with an average value of 60 um.

If the intention is to introduce foods or other consumable items into the bags, all of the materials, in particular polymers and additives, are designed to be suitable for use with foods. PVC, silicones, PET, PA, PP, PE, ULDPE, VLDPE, LLDPE, LDPE, MDPE, HDPE, EVA, EBA, EAA, EMA, and EMAA comply with these requirements.

The invention is explained in more detail by using an inventive example, with reference to the drawing.

The figure specifically shows a bag 1 in the form of a flat bag as in the invention, composed of a rough film 2 and of an opposite smooth film 3, and welded together at the respective edges. The bag 1 has an aperture 4 for the adhesive fastening of a screw-thread closure which has circular cross section and is not depicted in the drawing.
The lateral film 2 has been designed as multilayer film. The film 2 has been coextruded in three layers in a blown-film system and has a rough internal side 5, TERGAU & WALKENHORST Page 8 Patent Attorneys where the rough internal side 5 faces toward the internal side of the bag. The external side 6 of the film 2 is smooth. The rough internal side 5 and the smooth external side 6 of the film 2 have been manufactured from LLDPE, and for the roughening of the internal side 5 here coarse silica has been admixed only into said layer as roughening additive alongside lubricants, fine antiblocking agents, and processing aids. The film 2 is white by virtue of admixture of titanium dioxide to LLDPE. The opposite film 3 has likewise been manufactured from LLDPE with identical design except for the absence of the surface-roughening additive.

In summary, the nature of the bag 1 is such that, when complete emptying occurs, with collapse, for example through discharge of the contents using a suction lance, the film 2 comes into contact with the opposite smooth film 3, in such a way that no adhesion can take place between said two shell-shaped films. Because there is no adhesion, by way of example syrup contents can flow in their entirety to the discharge point, without any formation of vesicles which retain the syrup.

TERGAU & WALKENHORST Page 9 Patent Attorneys Key 1 Bag 2 Film 3 Smooth film 4 Aperture for closure 5 Rough internal side 6 Smooth external side

Claims (8)

1. A flexible bag which comprises at least one film and which is intended to receive and discharge fluids, pastes, or gases, or a bag which at the juncture of charging solid contents has been gas-filled, with at least one partially or completely rough internal side.

2. The bag as claimed in claim 1, characterized by at least one rough internal side (5) which is completely congruent with another opposite film (3).

3. The bag as claimed in claim 1 or 2, characterized in that the rough internal side of the film comprises at least one polymer and at least one surface-roughening additive.

4. The bag as claimed in claim 3 characterized by surface-roughening additives, preferably of mineral and/or inorganic and/or organic nature, or else a mixture thereof, where these do not melt together with the main raw materials of the composite film, where the additives in particular are sand or clay or silica or quartz or silicic acids or kieselguhr or silicates or crosslinked polymers, in particular UHMWP, or other heat-resistant polymers or a mixture thereof.

5. The bag as claimed in any of claims 1 to 4, characterized in that the bag has been manufactured from flexible plastics, in particular PVC, silicones, PET, PA, POP, PP, PE, ULDPE, VLDPE, LLDPE, mLLDPE, LDPE, MDPE, HDPE, EVA, EBA, EAA, EMA, EMAA, and ionomers, or else a mixture or copolymer thereof.

6. The bag as claimed in any of claims 1 to 5, characterized in that the bag is composed of two and/or more opposite free film plies welded at the edges.

7. The bag as claimed in any of claims 1 to 6, characterized in that the bag, or at least one film of the bag, has been produced by coextrusion.

8. The bag as claimed in any of claims 1 to 7, characterized in that the bag, or at least one film of the bag, has been produced from a laminated film.