AU2011100570A4

AU2011100570A4 - Improved Packaging Material

Info

Publication number: AU2011100570A4
Application number: AU2011100570A
Authority: AU
Inventors: George Ganzenmuller
Original assignee: Amcor Pty Ltd
Current assignee: Amcor Pty Ltd
Priority date: 2011-05-18
Filing date: 2011-05-18
Publication date: 2011-06-23
Anticipated expiration: 2019-05-18

Abstract

The invention relates to a packaging material comprising an active chemical or an active agent sealed between two substantially impermeable layers, and a further agent that interacts with a treatment process to cause openings to form in at least one of the layers such that the active chemical or active agent is exposed to an atmosphere.

Description

INNOVATION PATENT APPLICATION in the name of Amcor Limited entitled Improved Packaging Material Prepared by Cullens Patent & Trade Mark Attorneys Level 32, 239 George Street Brisbane QLD 4000 Australia Phone: 073011 5555 Fax: 0732293384 Email: mail@cullens.com.au 07 3229 6598 IMPROVED PACKAGING MATERIAL FIELD OF THE INVENTION The present invention relates to an improved packaging material. More particularly, the present invention relates to an improved packaging material that incorporates one or more active agents or active chemicals. BACKGROUND TO THE INVENTION Many packaging materials and transport and storage containers includes one or more active agents designed to improve the storage qualities of produce or products contained therein. For example, it is known that ethylene gas causes ripening of fruit and vegetables. Many fruit and vegetables naturally form ethylene gas and this can lead to increased rates of ripening when those fruits and vegetables are being stored and/or transported. If ripening proceeds too far due to the endogenous generation of ethylene gas, the fruits and vegetables can spoil during transport and storage. Acetylene gas had a similar effect. In order to overcome this problem, there have been a number of attempts to provide packaging materials and containers that remove ethylene gas from the environment within the container. For example, WO 01/30658 describes a paperboard one-piece container that forms a chamber divided into two compartments by an interior wall which provides fluid isolation between the two compartments. Each compartment has a container outer wall with a removable panel forming an opening in the outer wall. The opening is sealed with a permeable liner for permitting air to flow into the compartments while entrapping powder particles in the compartments. An odour absorbing powder is in the larger of the two compartments and an ethylene absorbing powder is absorbed to zeolite wrapped in a fibrous plastic film wrap in the smaller compartment. JP 2000279085 describes a freshness keeping agent obtained by laminating a moisture absorbing and releasing layer to the substrate and holding a metabolic gas regulator and an air permeable buffer layer.

2 JP 2215527 describes a packaging sheet that comprises a paper sheet, a synthetic resin, and a powder that adsorbs ethylene gas and another powder that issues far infra-red rays at room temperature, with the powders being dispersed between the paper sheet and the resin film. The packaging sheet is used for manufacturing bags or cartons for packing fresh fruit and vegetables. The film adsorbs liberated ethylene gas to prevent the ripening of fruit and vegetables and retains water by the far infrared energy issued from the powder issuing far infrared rays to retain freshness. JP 1146933 describes a packaging material which can keep vegetables fresh for a long period of time by adding fine particles of a clay ore and a far infrared radiating mineral to the more material for paper or synthetic resin. CN 101670690 describes a method for manufacturing an attapulgite preservative corrugated cardboard. The corrugated cardboard is made of a seven layer double corrugated cardboard composite material. The inner layer of the cardboard is coated with an attapulgite fruit and vegetable preservative paint. This packaging box can kill and restrain various mildews, bacteria and other putrefying bacteria, can absorb ethylene gas and can effectively reduce the loss of nutritional materials and waters from the fruits and vegetables. JP 2006224994 describes a freshness retaining paper that is obtained by coating a styrene acryl copolymer binder that has been mixed with charcoal powder onto the storage surface of a moisture retaining and waterproof paper. The paper has excellent gas adsorption properties, waterproof properties, heat resistance and moisture retaining properties. JP 3232801 describes a freshness retaining material useful for retaining freshness of vegetables, fruits, flowers and ornamental plants. The material is obtained by forming an ethylene absorbing layer composed of carbon black carrying a palladium compound thereon and a binder on a substrate. JP 2180141 describes a wrapping for maintaining the freshness of a perishable article, such as cut flowers. The wrapping comprises a resin film that is air permeable and vapour impermeable laminated onto a layer of paper containing an absorbent absorbing ethylene 3 gas and a far infrared radiation agent for radiating far infrared rays at normal temperature and pressure. One issue that does arise with many prior art packaging materials and containers that contain active agents involves degradation of the active agents during storage and/or transport of the packaging material or containers prior to their use to store products or produce. To provide but one example, where the packaging material forms part of a paperboard container, it is common practice to manufacture the containers in the form of paperboard blanks. The paperboard blanks lie essentially flat for enhanced storage and transport. When it is desired to use the paperboard blanks as storage containers, the blanks are folded up into containers or boxes and the products or produce placed in the containers or boxes. In some circumstances, an extended period of time may pass during which the blanks are stored prior to being folded up or erected into boxes. In such circumstances, the active agents in the package material from which the blanks are made are often exposed to various atmospheres that can consume or degrade the active agents during storage of the blanks. This can have the effect of reducing the useful storage life of the packaging material. The present applicant does not concede that the prior art discussed in the specification forms part of the common general knowledge in Australia or elsewhere. Throughout the specification, the term "comprising" and its grammatical equivalents shall be taken to have an inclusive meaning unless the context of use indicates otherwise. BRIEF DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a packaging material that overcomes or at least ameliorates one or more of the above-mentioned disadvantages, or provides a commercial alternative. In a first aspect, the present invention provides a packaging material comprising an active chemical or an active agent sealed between two substantially impermeable layers, and a 4 further agent that interacts with a treatment process to cause openings to form in at least one of the layers such that the active chemical or active agent is exposed to an atmosphere. In one embodiment, the further agent is applied to at least one of the layers. The further agent may be applied to at least one of the layers by a printing process or by a coating process. In another embodiment, the further agent is incorporated into at least one of the layers. In this embodiment, the further agent may be mixed into the material or materials from which at least one of the layers is manufactured. In another embodiment, the further agent is positioned between the two substantially impermeable layers. The packaging material of the present invention may be laminated to a substrate material. The packaging material may be laminated to a paperboard material, such as a corrugated paperboard. The paperboard material may be a single faced corrugated paperboard, double faced corrugated paperboard, twin cushion corrugated paperboard, triple flute corrugated paperboard or Duo Arch corrugated paperboard. This list is not exhaustive. Other substrate materials, such as substantially rigid plastics materials, glass, fibreglass, fibreboard, lightweight cementitious materials, metals or metal alloys may also be used as the substrate. Again, this list is not exhaustive. The layers of substantially impermeable material may comprise layers of polymeric material. The layers of polymeric material may comprise sheets or films of polymer. The layers of substantially impermeable material should have low permeability to gases and liquids. Examples of materials from which the substantially impermeable layers can be made include polyethylene terephthalate (PET), or polyethylene, such as MDPE, or polypropylene. In one embodiment, the outer film would be a high temperature polymer such as PET which has the active chemical or active agent applied as a reverse printed layer, and the inner film could be in the form of a tie layer that could be a variety of co extruded polymers such as MDPE or polypropylene. This polymer tie layer adheres the 5 outer film to the base paper and seals the active constituents from the atmosphere until treated. The active chemical or active agent may be present in the form of particulate material or as a powder. The active agent may be evenly spread between the two layers. Alternatively, the active agent may be positioned in discrete regions. As a further alternative, the active agent may be relatively more concentrated in some regions and relatively less concentrated in other regions. Indeed, the present invention could incorporate embodiments in which the active agent is relatively concentrated at regions where a greater requirement for the active agent is present during use of the packaging material. For example, a greater amount of the active agent may be required in the base and at the lower part of side walls of a packaging container and packaging material may be arranged such that greater amounts of the active agent at present in those regions than in other regions of the container. The active chemical or active agent may be selected from a wide variety of agents. Examples include adsorbents, absorbents, moisture absorbing agents, fungicides, biocides, mould killing agents, enzymes, chemically reactive agents, oxidising agents, reducing agents, or perfumes. This list is not exhaustive. When the packaging material is to be used for packaging fruit, vegetables, flowers or other plants or plant material, the active chemical or active agent may comprise one or more agents that can adsorb or absorb gases that can hasten ripening or rotting of the fruit, vegetables, flowers or plants. The active chemical or active agent may comprise an agent that can remove ethylene or can remove aldehyde gas. Examples include activated charcoal, zeolites, potassium permanganate, clay materials, and attapulgite. The packaging material of the present invention seals the active chemical or active agent between two substantially impermeable layers. This effectively seals off the active chemical or active agent from any deleterious effects that may be caused by exposing the active chemical or active agent to an atmosphere. Thus, the storage life of the packaging material can be significantly longer than known packaging materials that include active chemicals or active agents. When it is desired to use the packaging material and to take advantage of the beneficial effects of the active chemical or active agent, the packaging 6 material is subject to a treatment that causes openings to form in at least one of the layers. Formation of such openings provide at least a degree of permeability or porosity to at least one of the layers such that the active chemical or active agent is exposed to atmospheric components. The openings that may be formed may comprise very small openings such that atmospheric components can pass through the openings and contact the active chemical or active agent whilst still allowing the at least one layer to retain the active chemical or active agent between the two layers. Suitably, the at least one layer may have a microporous pore structure following exposure to the treatment. Following the treatment, the packaging material can be used to store and/or transport products or produce. As the active chemical or active agent is now exposed to the atmosphere, the active chemical or active agent can interact with components in the atmosphere (which could be gaseous components or liquid components, or both) to thereby minimise the deleterious effects that would be caused by those components. In other embodiments, the active components may provide beneficial components to the products or produce packaged within the packaging material. Suitably, the packaging material is subject to the treatment to form openings in the at least one layer just prior to using the packaging material to package, store or transport products or produce. A number of different treatments may be used to form the openings in the at least one layer. In one embodiment, the treatment may comprise a corona discharge treatment. The corona discharge may interact with the further agent to cause the openings to form in the at least one layer. The corona discharge treatment may cause arcing due to the presence of the further agent and the arcing may result in the formation of the openings in the at least one layer. In this embodiment, the further agent may comprise a carbonaceous material or a metallic material. The carbonaceous material or the metallic material may comprise particulate carbonaceous material or particulate metallic material. The carbonaceous material or the metallic material may comprise a carbonaceous material-containing ink or a metallic material-containing ink. The ink may be printed on to a surface of at least one of the layers. Suitably, the ink is printed on to a surface of at least one of the layers that is positioned adjacent to the surface of the other layer. In this manner, any arcing that will 7 occur will result in an arc extending through one of the layers which, in turn, will result in the formation of openings in that layer. In other embodiments, the further agent may comprise a frangible material that can be broken by application of physical force or pressure to thereby form openings in the at least one layer. The frangible material may suitably be incorporated into the layer in this embodiment. The treatment may comprise subjecting the packaging material to a rolling step whereby the packaging material passes under a roller or through a set of rollers. In another embodiment, the further agent may comprise a soluble agent and the treatment may comprise contacting the packaging material with a solvent for the soluble agent. As the soluble agent dissolves, voids or openings are left in the at least one layer. In accordance with a second aspect, the present invention provides a packaging material comprising an active chemical or an active agent sealed between two substantially impermeable layers, and a further agent that interacts with a treatment process to cause openings to form in at least one of the layers such that the active chemical or active agent is exposed to an atmosphere, wherein one of the layers is laminated to a packaging substrate. In accordance with a third aspect, the present invention provides a blank for a container, the blank comprising a substrate, a first substantially impermeable layer, a second substantially impermeable layer and an active chemical or an active agent sealed between the first substantially impermeable layer and the second substantially impermeable layer, and a further agent that interacts with a treatment process to cause openings to form in at least one of the first substantially impermeable layer and the second substantially permeable layer. In a fourth aspect, the present invention provides a method for forming a container comprising providing a blank for a container, the blank comprising a substrate, a first substantially impermeable layer, a second substantially impermeable layer and an active chemical or an active agent sealed between the first substantially impermeable layer and the second substantially impermeable layer, and a further agent that interacts with a treatment process to cause openings to form in at least one of the first substantially 8 impermeable layer and the second substantially permeable layer, subjecting the blank to the treatment, and erecting a container from the blank. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a cross-sectional view of a packaging material in accordance with a first embodiment of the present invention. Figure 2 shows a cross-sectional view of the packaging material of figure 1 being laminated to a corrugated paperboard; Figure 3 shows a front view of the packaging material shown in figures 1 and 2; and Figure 4 shows a side schematic view of the packaging material of figure 1 being subjected to a corona discharge treatment to cause openings to be formed in one of the layers. DETAILED DESCRIPTION OF THE DRAWINGS It will be understood that the drawings have been provided for the purposes of illustrating preferred embodiments of the present invention. Therefore, the present invention should not be considered to be limited solely to the features as shown in the drawings. Figure 1 shows a packaging material 10 in accordance with the present invention. The packaging material 10 comprises a first substantially impermeable layer 12 and a second substantially impermeable layer 14. An active agent, present in the form of discrete particles or powder of the active material, is shown schematically at 16. The packaging material also includes a further agent, which is in the form of discrete regions and is shown schematically in figure 1 at 18. It will be understood that the active agent 16 is shown as a rectangular shape and the further agent 18 is shown as a round shape in figure 1 so that they can be clearly distinguished from each other in the drawings. It will be understood that the active agent and the further agent do not necessarily need to take those configurations.

9 The packaging material 10 shown in figure 1 may be formed by placing the active agent 16 on to first layer 12 or, more preferably, by printing the active agent 16 onto second layer 14. The second layer 14 can then be placed over the top of the active agent 16 and the first layer 12 and the second layer 14 joined to each other. The further agent 18 may be positioned between the first layer 12 and the second layer 14. For example, the further agent 18 may be coated onto a lower surface of the second layer 14. The further agent 18 may also be reverse printed onto the second layer 14. The further agent 18 may be coated onto the upper surface of the first layer 12. The second layer 14 forms the outer layer and this layer is suitably a high temperature resistant polymer, such as PET. The first layer 12 may be a tie layer of polyethylene or polypropylene that is co-extruded with the second layer 14 and acts to bind or adhere the second layer 14 to a substrate. The first layer 12 and the second layer 14 act to seal the active agent 16 from the atmosphere until further treatment exposes the active agent 16. In order to seal the active agent 16 between the first layer 12 and the second layer 14, the first layer 12 and the second layer 14 may be joined to each other, for example, by laminating the first layer 12 to the second layer 14. The first layer 12 may be joined to the second layer 14 by using an adhesive, by heat joining the first layer 12 to the second layer 14 (in a manner that ensures that the integrity of the first layer 12 and the second layer 14 is not compromised), by ultrasonic welding, by co-extruding the layers or by use of any other process that can join the first layer 12 to the second layer 14. Figure 2 shows the packaging material 10 being laminated to a corrugated paperboard 20. The corrugated paperboard 20 comprises a corrugated medium 22 having a first liner 24 and a second liner 26 laminated thereto. The packaging material 10 is itself laminated to the upper surface of the liner 24. The packaging material 10 may be laminated to the corrugated paperboard 20 using any laminating technique known to be suitable to a person skilled in the art. For example, the packaging material 10 may be laminated to the corrugated paperboard by use of an appropriate adhesive. The first layer 12 may itself comprise an appropriate adhesive layer. Figure 3 shows a top view of the packaging material 10 shown in figure 1. As can be seen from figure 3, the further agent 18 is positioned in the form of discrete regions of the further agent 18. The discrete regions of further agent 18 are formed in a pattern such that 10 a desired and controlled microporosity is obtained when the packaging material 10 is subjected to the treatment that causes openings to be formed in the second layer 14. It will be appreciated that the further agent 18 may be positioned in a wide variety of different patterns. It is not necessary that the further agent 18 be located or formed into uniform patterns. Indeed, if higher porosity is required at some regions of the packaging material when the packaging material is in use, the further agent 18 may be relatively more concentrated in those regions. The skilled person will really understand that how to best place the regions of further agent 18 will in the packaging material 10. Figure 4 shows a schematic side view of a treatment that is used to form openings in the second layer 14. In figure 4, a corona discharge apparatus 30 provides a corona discharge that impinges upon packaging material 10 as the packaging material 10 passes underneath the corona discharge. The further agent 18 comprises a material that causes arcing when exposed to a corona discharge. Arcing is shown schematically in figure 4 by reference numeral 32. As the further agent 18 is located between the first layer 12 and the second layer 14, the arcing that is caused by the interaction of the corona discharge treatment with the further agent 18 results in arcs travelling from the further agent 18 through the second layer 14 and up to the corona discharge treatment apparatus 30. The effect of the arcs travelling through second layer 14 is to cause holes to be formed in the second layer 14. Once these holes have been formed, the second layer 14 contains openings that allow atmospheric components to access the active agent 16 via diffusion through or passage through the opening that have been formed in the second layer 14. In one specific embodiments of the examples shown in figures 1 to 4, the first layer 12 and the second layer 14 comprise sheets or films of polymeric material, such as sheets or films of PET (for layer 14) and polyethylene or polypropylene (for layer 12). The further agent 18 is printed on to the lower surface of second layer 14. The further agent 18 comprises an ink that has carbonaceous components or metallic components. For example, the ink may comprise a printing ink that includes graphite particles or particles of aluminium. The ink may be applied to the second layer 14 using any known printing process, such as flexographic printing or gravure printing.

S1I In order to form the packaging material 10, the first layer 12 is positioned on a surface and the further agent 16 is applied to the upper surface of first layer 12. The further agent 16 may be applied to the surface of first layer 12 by spraying, dusting, wiping, painting, by use of a spreading blade or even by printing the further agent on to the upper surface of first layer 12. The second layer 14 is then positioned over the top of first layer 12 and the first layers 12 and 14 are laminated together. This seals the active agent 16 between the first layer 12 and the second layer 14, thereby protecting the active agent 16 from exposure to the atmosphere. Alternatively, the active agent 16 and the further agent 18 may be reverse printed onto second layer 14 and the first layer 12 so-extruded woth the second layer 14. The packaging material 10 may then be laminated to the corrugated paperboard 20. The corrugated paperboard may then be formed into a container blank using conventional blank forming machinery. The container blanks may then be shipped to a user and stored by the user until the user is ready to erect the container blanks into a container. It will be appreciated that the container blanks may need to be stored for a considerable period of time, for example, 1 to 2 years, prior to the user wishing to form the blanks into containers. This period of storage is not detrimental to the action of the active agent because the active agent is effectively sealed off from the atmosphere. In this regard, it will be understood that the first layer 12 and the second layer 14 are made from substantially impermeable materials. However, all materials have a degree of permeability. Suitably, the first layer 12 in the second layer 14 have permeability that is sufficiently low so that the active agent is not unduly degraded during the storage period. When the user is ready to use the blanks by erecting the blanks into containers, the user takes the blanks and passes them under a corona discharge. The corona discharge treatment causes a number of small holes to form in the second layer 14. This results in the second layer 14 having a degree of porosity. Suitably, the porosity is such that atmospheric components, such as gases and liquids, can access the active agent 16, but the porosity is not so high that the active agent 16 can be separated from between the layers 12 12 and 14. In other words, the porosity that is formed in the packaging material 10 should not be so large that the active agent is no longer retained between the layers 12 and 14. The container blanks can then be erected into a container and the container used to hold, store and transport products and produce. In some embodiments, the packaging material 10 is positioned on the inside of the container. In this manner, the packaging material 10 can address the deleterious effects of atmospheric components within the container (and also in contact with the products or produce inside the container). For example, if the container is used to store fruit, vegetables, flowers or other plant material, the active agent 16 may comprise an adsorbent for ethylene. Therefore, ethylene that is generated endogenously by the fruit, vegetables, flowers or plant material within the container can be absorbed by the active agent with such that a low ethylene concentration is maintained in the container. This slows rotting or spoilage of the fruit, vegetables, flowers or plant material stored in the container. Advantageously, the present invention allows a packaging material to be formed that can be stored for significant periods without suffering undue degradation of the active agent. When it is desired to use the packaging material, the packaging material can be treated to expose the active agent to atmospheric components. Those skilled in the art will appreciate the present invention may be susceptible to variations and modifications other than those specifically described. It will be understood that the present invention encompasses all such variations and modifications that fall within its spirit and scope.

Claims

1. A packaging material comprising an active chemical or an active agent sealed between two substantially impermeable layers, and a further agent that interacts with a treatment process to cause openings to form in at least one of the layers such that the active chemical or active agent is exposed to an atmosphere.

2. A packaging material as claimed in claim 1 wherein the further agent is applied to at least one of the layers by a printing process or by a coating process.

3. A packaging material comprising an active chemical or an active agent sealed between two substantially impermeable layers, and a further agent that interacts with a treatment process to cause openings to form in at least one of the layers such that the active chemical or active agent is exposed to an atmosphere, wherein one of the layers is laminated to a packaging substrate.

4. A blank for a container, the blank comprising a substrate, a first substantially impermeable layer, a second substantially impermeable layer and an active chemical or an active agent sealed between the first substantially impermeable layer and the second substantially impermeable layer, and a further agent that interacts with a treatment process to cause openings to form in at least one of the first substantially impermeable layer and the second substantially permeable layer.

5. A method for forming a container comprising providing a blank for a container, the blank comprising a substrate, a first substantially impermeable layer, a second substantially impermeable layer and an active chemical or an active agent sealed between the first substantially impermeable layer and the second substantially impermeable layer, and a further agent that interacts with a treatment process to cause openings to form in at least one of the first substantially impermeable layer and the second substantially permeable layer, subjecting the blank to the treatment, and erecting a container from the blank.