PACKAGE AND PACKAGING METHOD

Abstract: This invention relates to packages, and methods of packaging, having particular application for free-flowing solids material, such as powders, granulated material and the like. Free-flowing material is contained in a first container (2), mainly formed from substantially impermeable material but including one or more gas-permeable portions (4). The or each gas-permeable portion (4) may be in the form of a longitudinal strip or patch sealing engaged in or integrally formed with the substantially impermeable portion (5). The gas-permeable portion or portions enable the application of a vacuum to the interior of the first container (2) when closed. In the preferred form of package, the first container (2) may be enclosed within an outer container (3) of substantially impermeable material, which container is vacuum sealed. For the packaging of products having stringent hygiene requirements, such as milk powders, the vacuum may be applied to the inner container (2) first and the or each gas-permeable portion (4) sealed with sealing means prior to vacuum-sealing of the inner container (2) within the outer container (3). The packaging method may employ form-filling of the inner container to produce a rectilinear block product which is more conveniently stackable and transportable.

Description: PACKAGE AND PACKAGING METHOD TECHNICAL FIELD This invention relates to a packaging method and package, and in particular a package for free-flowing material such as powder, granulated material or larger particulate material. BACKGROUND ART The nature of the method and package of this invention make it applicable to the packaging of a free-flowing material. The term "free- flowing material" is used hereinafter to include any solid material in a free- flowing form, from fine powders to granular material, to larger particulate material such as tablets, capsules, nuts, sweets, and the like. However, it will be appreciated that the invention is primarily directed at the packaging of products for which vacuum packaging is necessary or desirable for hygiene and product preservation reasons and/or to facilitate packaging in a form suitable for bulk transportation. There are many products which need to be packaged in a substantially sealed environment. In the process of such packaging, air or an inert gas employed during the packaging process may be trapped with the product in the sealed package. This is particularly the case with the packaging of free- flowing material, such as milk powders, flour, pigments, cement and the like, and also with packaging at high speed. Trapped air or gas in a sealed flexible package causes difficulties when a plurality of packages are stacked for storage or transportation purposes. One problem is the instability which the trapped air or gas creates in the stacked packages. A secondary problem is the risk of bursting of packages under compression. A third problem is possible oxidation of product. In addition, any trapped air or gas adds to the volume of a package which adds to the cost of transportation where that cost is measured by volume rather than weight. Packages made of paper may provide the required permeability to allow the escape of trapped air or gases, but they do not provide the protection from contamination required with certain products such as milk powders, flour and other food products. They are also vulnerable to damage through moisture or extremes of temperature. Composite packages involving two or more layers of different materials, including paper and plastics have been employed, but such composite packages can be costly to produce and dispose of. Valved plastic bags are also known in which the package is filled with a powder or granulated product through a valve sealed in a side of the package. However, air or gases may still be sealed in the package once the valve is closed. A further known method of dealing with trapped air or gases in packages has been to provide perforations through parts of the package walls. Unfortunately, however, perforations provide the opportunity for contamination, and may only be suitable for solid or granular product which will not escape through or block the perforations. Milk powder is an example of a product generally packaged in high vo lumes and therefore requires fast and efficient packaging. Using conventional methods, milk powder, for example, is packaged in flexible bags. Typically, these bags are made of at least two layers, an external layer of craft paper (which may in fact be 3 or 4-ply) and an internal layer of a plastics material. The loose milk powder in such a package has a relatively low density in view of the quantity of air trapped in the bags. Thus, considerable space is taken up in shipping containers and other transport media when the packaged milk powder is transported. This leads to considerable cost in freight charges. Understandably, these costs reflect adversely on the economics of exporting milk powder. Again because of the relatively low density of the packaged product, and inappropriate shaping of the containers, the conventional bags or containers once packed are not rigid which means that they cannot be efficiently stacked together for transportation. Furthermore, in conventional packages the inner plastics layer is generally bonded in some way to the outer paper layer or layers. This results in problems in recycling of used packages, and such packages may not be approved by regulatory bodies in some countries. There is also a perception that paper is less hygienic than plastics material, having a negative influence on potential buyers of product packaged in packages having a paper outer covering. From a marketing point of view, it is also a negative factor with conventional packaging that the packages are generally of a non-uniform shape, resulting in poor presentation of the product, difficulties in handling, and possible difficulties in clear labelling. Another particular problem associated with the packaging of milk powder is that it is an extremely dusty product and this creates difficulties in thermoforming and vacuum sealing of packages containing milk powder. Thus, it is an object of the present invention to provide a package and a method of packaging to reduce or overcome at least some of the abovementioned problems, or to at least provide the public with a useful alternative. Other objects of the present invention may become apparent from the following description which is given by way of example only. DISCLOSURE OF INVENTION According to one aspect of the present invention there is provided a method of packaging a free-flowing material, said method including the steps of: filling or partially filling a first container with a free-flowing material, said first container of substantially impermeable material but having at least one gas-permeable portion sealingly engaged or integrally formed with the substantially impermeable portion; closing said first container; applying a vacuum to the first container through said one or more gas-permeable portions; and sealing said first container. In one preferred form, the first container may be sealed by the application of closure means over the or each gas-permeable portion. Alternatively, or additionally, the first container may be sealed by being sealed within a second container of substantially impermeable material. In a preferred form, the vacuum may be applied to the second container before sealing. Alternatively, the vacuum may be applied in two stages, first to the first container through the one or more gas-permeable portions, and subsequently to the second container, with the first container enclosed, prior to sealing of the second container. In a further preferred form, the method may further include the step of positioning the first container in a forming box prior to filling, to enable form filling. According to a further aspect of the present invention, there is provided a package of free-flowing material under vacuum, said package including a first container predominantly of a substantially impermeable material but having at least one gas-permeable portion sealingly engaged or integrally formed with said substantially impermeable material, and closure means adapted to seal the or each gas-permeable portion and retain a vacuum within the package. In one preferred form, the closure means may include one or more stickers of substantially impermeable material sealingly engaged over the or each gas-permeable portion. Alternatively, or in addition, the closure means may include a second container of substantially impermeable material about said first container, and sealing the vacuum within the package. In one preferred form, the package may include a first vacuum in the first container, sealed by the application of one or more stickers of substantially impermeable material sealingly engaged over the or each gas- permeable portion, and a separate vacuum retained in the second container. In a preferred form of package, the or each gas-permeable portion may comprise a longitudinal strip or patch of gas-permeable material, sealed at its edges to the substantially impermeable material. Other aspects of the present invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: BRIEF DESCRIPTION OF DRAWINGS Figure 1 : Shows a perspective view of a package of the present invention, cut away in one corner; Figure 2: Shows a perspective view of an inner container of the present invention in one form; Figures 3A - 3C: Show perspective views of alternative embodiments of an inner container of the present invention; Figures 4A - 4C: Show diagrammatic cross-sectional views of a packaging method used in one embodiment of the present invention. Figures 5 - 9 Show schematic diagrams of apparatus of the present invention, in one preferred embodiment, employed in the production of a package of the invention. DETAILED DESCRIPTION OF INVENTION With reference to Figure 1 , a package 1 of the present invention in one embodiment comprises an inner container 2 and an outer container 3, the inner container 2 having a gas permeable portion 4 and a substantially impermeable portion 5. Ends 6 of the inner container and ends 7 of the outer container are sealed, a vacuum having been applied to the outer container 3 prior to sealing of one end of that container. It will be appreciated that the seals on the outer container may be oriented differently, for example longitudinally on one or both sides or faces of the package, depending on the method of sealing the outer container employed. With reference to Figures 2 and 3, the majority of the inner container 2 is of the substantially impermeable material, for example an impermeable, flexible plastics material, such as 60 micron gas barrier plastic. The gas permeable portion 4 may be in the form of a longitudinal strip, as in Figure 2, in the form of a patch or patches, as in Figures 3B, 3C, or in the form of a block section, as in Figure 3A. It will be appreciated that these are but examples of the positioning of the gas permeable portion, an important factor being that in production of the package at least a part of the gas permeable portion will be adjacent the site of application of the vacuum. From the point of view of convenience of manufacture, it will be appreciated that the embodiment of the inner container 2 of Figure 2 may be produced from a tube of material having a longitudinal strip of the gas permeable material sealed to the substantially impermeable material along its edges 8. Similarly, the embodiments of Figure 3B, 3C may also be formed from tubular material with the gas permeable portions comprising patches sealingly engaged in or over punched out portions of the substantially impermeable material at intervals along the length of the tube, determined according to the size of the packages required. The gas permeable portion of the inner container 2 has properties enabling the applied vacuum to be transferred to the inner part of the inner container 2, whilst prohibiting the transfer of any material contents from the inner container 2 to the outer container 3. In addition, the gas-permeable portion will preclude the passage of micro-organisms into the first container. Ideally, it or they would allow the efflux but not the influx of air or gas. Without intending to limit the scope of the term permeable material, examples may include gas-permeable plastics, paper or textile. The degree of permability of the gas-permeable portion or portions will be dependent on the nature of the substantially impermeable portion, the type of sealing employed and the nature of the product packaged. The impermeable and permeable portions may be sealed together by welding, and each portion is therefore preferably made from a thermoplastics material. In an alternative embodiment, an inner container of the present invention may be formed from laminated layers of plastics material, one or more layers omitted in at least parts of the package to provide the gas- permeable portion or portions. In such an embodiment, the substantially impermeable and gas-permeable portions would be integrally formed rather than sealed together. A package 1 of the present invention may have a preformed shape, for example a brick-shape to facilitate bulk packaging. It will be appreciated that the shaping of a package may be achieved by shaping of the inner 2 and/or outer container 3, for example, by thermoforming or through the application of pressure. The outer container 3 may be made of any material that is gas impermeable so as to retain the vacuum applied. It is preferably a material which is structurally strong and yet flexible, such as a plastics material, so as to provide protection for the inner container 2. The material of the outer container may include some material such as nylon to enhance the strength. It may also include mylar as a gas barrier. And it may optionally be of a material, or it may include a barrier layer, which protects photosensitive product, for example it may include a UV barrier. It will be appreciated that no sealing is required between the inner container 2 and the outer container 3. Thus, the outer container may be easily pealed off the inner container, for simple recycling or disposal. Once the product has been removed from the inner container, then that too can be separately recycled or disposed of. In the above description, reference is made to the vacuum being applied within the outer container, and being transferred through to the inner container via the gas-permeable portion or portions. For some products, and particularly where hygiene requirements are stringent, it is envisaged that the gas-permeable portion or portions of the inner container may themselves be sealed prior to the inner container being placed in the outer container. Thus, a vacuum may be applied to the inner container, a sticker or the like sealingly engaged over the or each gas-permeable portion, and the vacuum-sealed inner container than subsequently vacuum sealed within the outer container. With this configuration, the outer container may be stripped off the product and disposed of without interfering with the integrity of the product in the inner container. The packages described above, when formed and vacuum-packed, for example, in a rectilinear block, are more conveniently and efficiently transportable, since the volume of packaged product is reduced and the stability of stacked packages is increased. For some products, for example, those for which there are no hygiene issues, or less stringent hygiene issues, inner containers alone, in particular embodiments, may be suitable for packaging. In such packaging, the gas- permeable portion or portions are configured in such a way that when a plurality of the packages are stacked one on top of the other, any air or gas trapped in a package can escape through the gas-permeable portion or portions, thus facilitating the stability of a stack of packages. The gas- permeable portions would preferably be a longitudinal strip or strips extending over the ends of a package (as in Figure 2), a patch or patches at the ends of the package (as in Figure 3B) or strips or patches on the sides of the package. In such configurations, at least a part of the gas-permeable portion or portions are clear of any surface of the package which forms a contact surface with adjacent packages in a stack of packages. It will be appreciated that a package in this form, when closed, is secure from contamination by micro-organisms, whilst the gas-permeable portion enables the elimination of air or gas under pressure without breaking the package seal or seals, or the weld between the substantially impermeable and gas-permeable portions. A package of the present invention has particular application in the packaging of powdered materials, such as milk powder, protein concentrates, pharmaceutical products, alum, fertilisers and the like, where there can be a substantial amount of air trapped in the product during packaging. However, these packages will also have potential application for the packaging of other granulated or solids material, where there is a likelihood of air or gas being trapped in the package during packaging. The method of producing packages according to the present invention will now be described, by way of examples, with reference to the embodiments shown in the Figures. Example 1 Two rolls of tubular material are provided. The first roll is for forming the inner container 2, and comprises mainly impermeable material with a longitudinal strip or patches of gas permeable material. The second roll is of impermeable material and is for forming the outer container. It will be appreciated that the tubular material for the inner container may be preformed, or separate rolls of the gas permeable and impermeable materials may be sealed together to form the tube in the packaging machine itself. A first end of a length of tubular material for the first roll is sealed and the product to be packaged is fed in to the open inner container, for example through a conventional hopper-type feed. The second end of the inner container is then sealed. The closed inner container is then positioned in a length of the tubular impermeable material from the second roll, one end of which is sealed. The second end of the outer container 3 is then closed about a snorkel and a vacuum is applied causing the walls of the outer container and the inner container to contact one another, and drawing a vacuum on the inner container through at least a part of the gas permeable portion adjacent the point of application of the vacuum. The second end of the outer container 3 is then sealed. It will be appreciated that the package may have a preformed shape defined by preformed shaping of the inner and/or outer container, or it may be shaped during the packaging and vacuuming process. Example 2 Referring to Figure 4, an alternative method of applying the outer container 3 may be by thermoforming. The application of thermoforming enables the use in some embodiments of an easy-peel layer on the external packaging of the milk powder. In this embodiment standard thermoforming machinery may be set up with a bottom layer of gas impermeable film in a standard thermoforming cavity. The filled and closed inner container is placed into this thermoforming cavity. The cavity is then indexed to a thermoforming hood in order to apply a vacuum to the inner container and provide a sealed gas impermeable outer container. Figure 4A illustrates the first stage in the thermoforming process. In this stage an inner container 1 1 filled with product 1 2 is placed into a thermoforming cavity 1 3. The cavity 1 3 is lined with a gas impermeable plastics layer 14. The cavity 1 3 is then indexed forward to where a thermoforming hood 1 5 (see Figure 4B) is positioned. At this stage a vacuum is applied to the cavity 1 3 causing air to leave the contents 1 2 of the inner container 1 1 , via the gas permeable portion or portions (not shown). This application of a vacuum also causes the inner container 1 1 to settle below the top of the cavity 1 3, to form a substantially blocklike shape (see Figure 4C). Example 3 This Example is described with reference to Figures 5 to 9. Referring to Figure 5, a web of material 51 from which the inner container is formed is opened up and the end cuffed over an open end 53 of a forming box 52. Means 66 are provided to separate a sealed end of the inner container 54 from the rest of the web 51 . A blow/suck operation, employing an air inlet/outlet 55, is used to first inflate and then invert the inner container 54 into the forming box 52. Moving to Figure 6, the forming box 52 is then rotated to a vertical position, and the product to be packaged is introduced to the inner container 54 via hopper 56. The cuff 64 of the inner container 54 is then released and this end of the inner container 54 is sealed by sealing means 67. Turning to Figures 7 and 8, the forming box 52 is rotated to the horizontal and supported by carriage 59. A lid 65, which may form part of the carriage, is closed over the open end 53 of the forming box 52 (see Figure 8). One side 57 of the forming box 52 includes slots or perforations (not shown) at a central part. This side 57 now forms an upper surface of the forming box 52. The inner container 54 within the forming box 52 is configured such that the permeable portion or portions are on the side of the inner container 54 adjacent this side 57 of the forming box 52. With the closed forming box 52 supported by carriage 59, rams 60 are positioned above side 57 of the forming box 52. This side 57 is a false side, moveable in and out, such that the thickness of the forming box 52 may be reduced by the application of pressure to this side 57. The forming box 52, with its inner container 54 and contents, is subjected to vibration on the carriage 59 and pressure from the rams 60 to expel air and form the shape of the inner container 54 within the forming box 52. A vacuum is then applied through the slotted/perforated central part of the side 57 of the forming box 52, drawing any remaining air or gases from the inner container 54 through the gas-permeable portion or portions. With reference to Figure 9, the lid 65 then removed and the formed inner container 61 is removed from the forming box 52. As the formed inner container 61 is removed, a sticker or stickers may be applied over the or each gas-permeable portion to seal the inner container. Alternatively, the formed inner container 61 may be transported to the outer container sealing apparatus 62 via suction means (e.g. one or more suction cups) which continue to apply a vacuum to the inner container via the gas-permeable portion or portions. The formed inner container 61 is then positioned in an outer container 68 of substantially impermeable material, a snorkel 63 inserted into the outer container 68, a vacuum is applied to the outer container 68 and this container is then sealed. Alternatively, the outer container may be applied by flow wrapping, with a vacuum applied within the outer container during the flow wrapping process. It will be appreciated that this example differs from example 2, primarily in that the primary shape of the package is formed on the inner container rather than the outer container. It also differs in the optional application of a sticker or stickers over the gas-permeable portion(s) to provide for additional sealing of the product in the package as a whole. It will be appreciated that the method and package of the present invention has particular application in the packaging of powdered materials such as milk powder, protein concentrates, pharmaceutical products, alum, fertilisers and the like, although it also has potential application for other free- flowing solids material such as granular material. Thus, the method and package of the present invention provides an efficient means for packaging of powder or granulated products. The application of a vacuum substantially increases the density of the contents of the inner container resulting in a reduced volume of the packaged products and a more conveniently shaped package for easier handling, stacking and bulk transportation, thus providing the opportunity to considerably reduce freight costs. Since the inner and outer containers are readily separable, recycling of the packaging material is facilitated. The use of an outer layer of plastics material improves the mechanical strength and hygiene of the pack in comparison with packages employing an outer layer of paper. Furthermore, because of the substantially rigid form, and regular size and shape of packages of the present invention, printing and labelling is facilitated, with the result that package presentation is improved. Where in the foregoing description reference has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth. Although this invention has been described by way of example and with reference to possible embodiments thereof it is to be understood that modifications or improvements may be made thereto without departing from the scope or spirit of the invention, as defined in the following claims.

Claims: CLAIMS 1 . A method of packaging a free-flowing material, said method including the steps of: filling or partially filling a first container with a free-flowing material, said first container of substantially impermeable material but having at least one gas-permeable portion sealingly engaged or integrally formed with the substantially impermeable portion; closing said first container; applying a vacuum to the first container through said one or more gas-permeable portions; and sealing said first container. 2. A method according to claim 1 wherein the first container is sealed by the application of closure means over the or each gas-permeable portion. 3. A method according to claim 2 wherein the closure means comprises one or more stickers of substantially impermeable material. 4. A method according to claim 1 wherein the first container is sealed by being sealed within a second container of substantially impermeable material. 5. A method according to claim 4 wherein the vacuum is applied to the second container, before sealing. 6. A method according to claim 4 wherein the vacuum is applied in two stages, first to the first container through the one or more gas- permeable portions, and subsequently to the second container, with the first container enclosed, prior to sealing of the second container. 7. A method according to claim 6 wherein closure means are applied over the or each gas-permeable portion of the first container after application of the first vacuum. 8. A method according to any one of the preceding claims further including the step of positioning the first container in a forming box prior to filling to enable form filling. 9. A method according to claim 8 further including the step of orienting the forming box in a first orientation for optimal gravity feed filling of the first container and rotating the forming box with the filled first container to a second orientation for optimal forming. 1 0. A method according to claim 8 further including the step of orienting the first container in the forming box so that at least a part of the one or more gas-permeable portions is adjacent a location on the forming box through which the vacuum is applied. 1 1 . A method according to any one of the preceding claims wherein the free-flowing material is milk powder. 1 2. A package for a free-flowing material under vacuum, said package including a first container predominantly of a substantially impermeable material but having at least one gas-permeable portion sealingly engaged or integrally formed with said substantially impermeable material, and closure means adapted to seal the or each gas-permeable portion and retain a vacuum within the package. 1 3. A package according to claim 1 2 wherein the closure means includes one or more stickers of substantially impermeable material sealingly engaged over the or each gas-permeable portion. 14. A package according to claim 1 2 wherein the closure means includes a second container of substantially impermeable material about said first container and sealing the vacuum in the package. 1 5. A package according to claim 14 wherein the closure means further includes one or more stickers of substantially impermeable material sealingly engaged over the or each gas-permeable portion to retain a vacuum in the first container, with a separate vacuum retained in the second container. 1 6. A package according to any one of claims 1 2 to 1 5 wherein the or each gas-permeable portion comprises a longitudinal strip of gas- permeable material sealed at its edges to the substantially impermeable material. 17. A package according to any one of claims 1 2 to 1 5 wherein the or each gas-permeable portion comprises a patch sealingly engaged in or over a punched out portion of the substantially impermeable material. 1 8. A package, according to any one of claims 1 2 to 1 7 wherein the substantially impermeable material is a flexible plastics material. 1 9. A package according to any one of claims 1 2 to 1 8 wherein the at least one gas-permeable portion is a flexible plastics material. 20. A package according to claim 1 9 wherein the substantially impermeable material and the or each gas-permeable portion are welded together. 21 . A package according to any one of claims 1 2 to 20 wherein the or each gas-permeable portion precludes the passage of micro-organisms into the first container. 22. A package according to any one of claim 1 2 to 21 wherein the shape of the first container is determined by it being form filled. 23. A package according to claim 22 wherein the package is in the shape of a rectilinear block. 24. A method of packaging a free-flowing material substantially as herein described and with reference to the accompanying drawings. 25. A package for a free-flowing material substantially as herein described and with reference to the accompanying drawings. JM:LS:CSPEC39613 - File Ref: JM501895-142

Inventors: ASHBY GORDON WALTER, ASHTON THOMAS FELIX, AUCAMP DAVID, ASHBY, GORDON, WALTER, ASHTON, THOMAS, FELIX, AUCAMP, DAVID
Applicants: ASHBY GORDON WALTER, ASHTON GROUP LIMITED, ASHTON THOMAS FELIX, AUCAMP DAVID, ASHBY, GORDON, WALTER, ASHTON, THOMAS, FELIX, AUCAMP, DAVID
Application year: 1998
Main classification: B65B31
IPC codes: B65B31, B65D75, B65D81