HUP0000725A2 - Bag-in-bag packaging system - Google Patents

Abstract

Packaging has an inner bag which is surrounded by, but removable from, an outer bag (201) each bag having a closed base and an open top. The inner surface of the mouth of the inner bag has a heat sealable zone (205), and the inner surface of the outer bag (201) has a non-heat sealable zone (205), corresponding to the location of the heat sealable zone of the inner bag, and a heat sealable zone (207), between the non heat sealable zone (205) and the mouth of the bag. During a heat sealing operation the inner bag can be sealed through the outer bag, without sealing the outer bag at the non heat sealable zone, and a sealing operation can be performed at least on the outer bag to create a second seal at (207) to close the outer bag, enclosing the inner bag. The method of filling and sealing the above package is also claimed in which the sealing operation on the outer bag in the heat sealable zone (207) seals the inner and outer bags together.

Description

Number: 314258

Country: New Zealand, NZ

Date: July 9, 1997 (97.07.09.)

Number: 328291

Country: New Zealand, NZ

Date: December 5, 1997 (97.12.05.)

Number: 329346

Technical area

This invention relates to packaging, in particular to multilayer flexible packaging, such as bag-in-bag packaging systems. More particularly, the invention relates to closure systems for flexible packaging purposes made of plastic and having an inner bag separated from an outer bag. Such packaging is suitable for packaging food or food-like substances or pharmaceuticals.

Background of the invention

The use of flexible packaging refers to the use of protective or industrial transport packaging in conjunction with an inner packaging that can be removed from the outer packaging while remaining sealed. The removable inner packaging serves the purpose of providing a hygienically packaged product that is free from contamination during transport and is suitable for transport into food hygiene critical areas.

There is a need to provide a flexible packaging as above, which is ready-made and has a sealed bag-in-bag system.

Definitions

A bag is a container device made of one or more layers of flexible material and sealed on at least one side. It includes, but is not limited to, bags, packages, pouches, pouches of all sizes and shapes. Although the size varies from country to country, the term bag is often used for container devices that are suitable for storing 10-40 kg of product. A sack refers to a container device that is used to store 10 kg or less of product. However, the term bag is a generic term used regardless of the weight of the product. The specification describes a bag-in-bag packaging system that

-2 suitable for storing, among other things, 25 kg of milk powder or milk powder derivatives, which in most countries is called a bag.

A bag essentially means a bag consisting of one or more flattened tubular sheets of flexible material (such as paper or plastic) which are closed on at least one side, the inner sheet being the wall of the inner bag.

The sheet refers to the sheet of flexible material that forms the wall of the bag. The two-sheet terminology refers to the bag-in-bag packaging system, i.e. the inner sheet refers to the wall of the inner bag.

Film refers to a flexible material (typically plastic) consisting of one or more layers.

The subject of the invention:

The object of the invention is to provide an improved packaging or improved closure arrangement for a multilayer flexible packaging and to provide benefits to the public.

One aspect of the invention broadly comprises a bag having at least two panels, comprising an inner panel which is disposed within but removable from an outer panel, a bag opening which combines the inner and outer closure means, the inner closure means which receives the inner panel only for closure, and the outer closure means which receives at least the outer panel for closure.

The two-plate bag refers to the bag-in-bag packaging system, the inner plate refers to the wall of the inner bag.

Preferably, a frangible zone is provided between the inner and outer closure means at least in the outer plate.

More preferably, the fragile zone is formed by a weakened line in at least the outer sheet material.

More preferably, the fragile zone is formed by a weakened line in both the inner sheet material and the outer sheet material.

Preferably, the inner seal and the outer seal are achieved by applying heat, which is applied through the layers of the inner and outer sheet.

Optionally, a non-weldable layer may be placed between the inner plate and the outer plate around the inner closure means of the inner plate, or alternatively, the inner plates may be

-3 may be weldable, but the outer plate is not welded by suitable selection of time/temperature/pressure and materials.

Preferably, the non-heat-sealable layer is selected from the following group, but is not limited to: solvent-based varnishes, water-based varnishes and silicone dispersions.

Preferably, at least the inner plate is made of weldable plastic.

More preferably, the weldable plastic thermoplastic or thermoplastic composites may be selected from the following group, but not limited to: polyethylene coated paper and polyethylene coated woven polypropylene.

Another aspect of the invention is a method for sealing a bag of at least two panels, the bag comprising an inner bag concealed within the outer panel but separable therefrom, and a bag opening comprising inner and outer closure means, the inner closure means receiving the inner panel only for closure and the outer closure means receiving at least the outer panel for closure.

Preferably, the frangible zone is located between the inner closure means and the outer closure means, at least in the outer plate.

More preferably, the fragile zone is formed as a weakened line at least in the outer sheet.

More preferably, the fragile zone is formed as a weakened line in both the inner and outer sheet material.

Preferably, the inner seal and the outer seal are formed by thermally bonding the inner and outer plates, with a non-weldable layer being disposed between the inner plate and the outer plate around the inner sealing structure of the inner plate.

A non-heat-sealable layer is preferably selected from the following group: solvent-based varnishes, water-based varnishes and silicone dispersions.

Preferably, at least the inner plate is made of weldable plastic.

More preferably, the weldable plastic thermoplastic or thermoplastic composites can be selected from the following group, but not limited to: polyethylene coated paper and polyethylene coated woven polypropylene.

One aspect of the invention broadly comprises a multi-panel bag comprising an inner panel and an outer panel made of a heat-sealable material, the inner panel being located within, but removable from, an outer panel, in which a non-heat-sealable material is used on the inner side of the outer panel or

-4 is close to or attached to the open end of the outer or inner plate on the outer side of the inner plate.

Preferably, a non-heat-sealable material is applied to the inner side of the outer sheet. Preferably, the non-heat-sealable layer is selected from the group consisting of solvent-based varnishes, water-based varnishes and silicone dispersions.

Preferably, a frangible zone is provided at least in the outer sheet, in the area of the non-heat-sealable material or above the non-heat-sealable material.

More preferably, a frangible zone is provided in the area of the non-heat-sealable material.

Preferably, the fragile zone is formed by a weakened line at least in the outer sheet material.

One aspect of the invention is broadly a method for sealing a bag of at least two panels made of non-heat-sealable material, the inner panel being located within an outer panel but removable therefrom, and wherein a strip of non-heat-sealable material is applied to the inside of the outer panel or the outside of the inner panel or is attached to the open end of the outer or inner panel.

Preferably, a non-heat-sealable material is used on the inner side of the outer sheet. Preferably, the non-heat-sealable layer can be selected from the following group: solvent-based varnishes, water-based varnishes and silicone dispersions.

Preferably, a frangible zone is provided at least in the outer sheet, in the area of the non-heat-sealable material or above the non-heat-sealable material.

More preferably, a frangible zone is provided in the area of the non-heat-sealable material.

Preferably, the fragile zone is formed by a weakened line in at least the outer sheet material.

Preferably, at least one heat seal is applied to the double-walled bag, where the heat seals extend below and above the region where the non-heat sealable material is used.

Alternatively, two heat seals are applied to the double-walled bag, an upper seal applied above the fragile zone and a lower seal applied in the region where the non-heat sealable material is used.

-5 A further aspect of the invention is broadly a multi-panel bag having an inner and outer panel made of a non-heat-sealable material, the inner panel being located within an outer panel but removable therefrom, and having a strip of non-heat-sealable material applied to the inner side of the outer panel or the outer side of the inner panel proximate or adjacent to the open end of the outer or inner panel.

Preferably, a heat-sealable material is used on the inner side of the outer plate.

Preferably, a frangible zone is provided at least in the outer sheet material, in the area of the non-heat-sealable material or above the heat-sealable material.

More preferably, a frangible zone is provided in the area of the heat-sealable material. Preferably, the frangible zone is formed by a weakened line in at least the outer sheet material.

A further aspect of the invention is a method for sealing a bag of at least two panels, made of a non-heat-sealable material, the inner panel being located within an outer panel but removable therefrom, and in which a strip of non-heat-sealable material is applied to the inner side of the outer panel or to the outer side of the inner panel adjacent or adjacent to the open end of the outer or inner panel. Preferably, a heat-sealable material is applied to the inner side of the outer panel.

Preferably, a frangible zone is provided at least in the outer sheet, in the area of the heat-sealable material or above the heat-sealable material.

More preferably, a frangible zone is provided in the area of the heat-sealable material. Preferably, the frangible zone is formed by a weakened line in at least the outer sheet material.

Preferably, at least one heat seal is applied to the double-walled bag, which heat seal is applied at least in the area of the heat-sealable material.

Another aspect of the invention provides a package comprising an inner bag having an inner and outer surface, surrounded by but separable from an outer bag having an inner and outer surface, each bag having a closed bottom and each bag having an open top, characterized in that the inner surface of the mouth of the inner bag has a heat sealable zone and the inner surface of the mouth of the outer bag has (a) a non-heat sealable zone corresponding to the location of the heat sealable zone of the inner bag and (b) a sealable zone between the non-heat sealable zone and the top of the bag, such that the heat sealing operation can be performed through the outer bag to create a first seal capable of sealing and sealing the mouth of the inner bag without welding

-6a outer bag in the non-heat sealable zone and the sealing operation can be performed at least on the outer bag to create a second seal to seal and seal the outer bag in its sealable zone to enclose the sealed inner bag within the outer bag.

In a further aspect of the invention, a method is provided for filling and sealing a package of the type described in the immediately preceding paragraph, having an inner bag surrounded by an outer bag but removable therefrom, characterized in that the package is filled by a filling machine until the inner bag is filled to the desired extent, the mouth of the bag is stretched to straighten the inner and outer bags in the first and second sealing zones, the inner bag is sealed along the first sealing zone to form the first seal without sticking to the outer bag and the inner and outer bags are sealed together in the area of the second sealing zone to form the second seal.

In a further aspect of the invention, there is provided a package comprising the package described above, having a filled inner bag surrounded by but removable from an outer bag, the inner bag being sealed by a first heat seal but the outer bag not being heat sealed to the inner bag at that point, the outer bag being sealed by a second seal located between the first seal and the top of the bag and a frangible zone located between the first and second seals, such that in use the outer bag can be removed from the sealed inner bag by tearing or cutting along the frangible zone.

A further aspect of the invention provides a method for filling, sealing and packaging a bag of the type described in the immediately preceding section, which has an inner bag surrounding but removable from it an outer bag, wherein the packaging

Drawings:

The following are the drawings that:

Figure 1: Side cross-section of the upper part of a two-sheet bag showing the welding configuration;

Figure 2 shows a base-based bag ready for filling;

Figure 3: shows the bag of Figure 2 when filled and sealed;

Figure 3A: Section A-A of the bag according to Figure 3;

Figure 4: the bag of Figure 3 with the outer bag partially opened, showing the opening of the outer bag, torn or cut along the perforation,

Figure 5: a base-based bag with the added portion providing a gripping means;

Figure 6 shows an additional section of normal length providing a gripping means at the base of the bag;

Figure 7 shows another arrangement in which the added part is fixed along both edges of the base of the bag,

Figure 8: a recessed cut closure of a two-sheet plastic bag having a first heat seal and a second heat seal separated by a perforation line;

Figure 9: recessed cut closure for a double-walled plastic bag having a first heat seal, a perforation line and a separate lid which is attached over the inner and outer bags,

Figure 10: upper stepped closure of a double-walled plastic bag having a first heat seal and a heat or pressure sensitive adhesive located in the stepped upper portion;

Figure 11: the bag according to Figure 10, with a pinched top closure for a two-sheet plastic bag having a first seal, a perforation line and a fold-down portion on the outer bag which can be folded over and sealed on the inner bag;

Figure 12 shows a schematic diagram of a plastic processing machine capable of producing a bag according to this invention;

Figure 13: shows a pear-shaped bag-in-bag arrangement for transporting liquid, shown before welding,

Figure 14 shows the arrangement of Figure 13 with the necks of two bags welded according to this invention;

Figure 15: cross-section of a bag construction in the simplest case to eliminate varnish-smear,

Figure 16: Cross-section of a preferred bag construction that utilizes a two-layer inner bag in conjunction with a three-layer outer bag to eliminate the applied varnish.

Figure 17: A cross-section of a preferred bag construction, similar to Figure 17, with an additional option for an inner bag providing an oxygen barrier.

First example

A two-sheet bag can be formed by known means. The bag sheet can be formed from thermoplastics or thermoplastic composites, or from other materials such as polyethylene-coated paper or polyethylene-coated woven fabric.

-8polypropylene. A feature of the invention is that the resulting bag has an inner bag contained within the outer bag but detachable from it. The outer bag can be detached after transport and the inner bag can be introduced into critical food hygiene areas, the inner bag remaining contaminated during transport and handling.

A multi-panel bag 100 is provided having an inner panel 101 and an outer panel 102. At least one end of the inner panel 101 and at least one end of the outer panel 102 can be closed to form an inner and an outer bag, respectively, each with an open end. The inner panel 101 and the outer panel 102 are made of a heat-sealable material, e.g., a thermoplastic plastic, or a thermoplastic composite of polyethylene-coated paper and polyethylene-coated woven polypropylene.

A non-heat sealable material 103, such as a solvent-based lacquer, water-based lacquer or silicone dispersion, is applied in a strip to the inside of the outer sheet 102 near the open end of the outer bag.

The 100 bags are delivered to the consumer for filling and sealing. In practice, two heat seals can be used for packaging.

The lower heat seal 104 is applied at the position of the non-heat sealable material 103. An upper heat seal 105 is applied above and parallel to the lower heat seal 104. A gap is preferably left between the lower 104 and the upper 105 heat seals. A fragile zone 106 is preferably provided in both the inner sheet 101 and the outer sheet 102 at a position between the lower 104 heat seal and the upper 105 heat seal. A fragile zone 106 is preferably provided by perforations in the inner sheet 101 and the outer sheet 102 at or just above the heat seal section. The fragile zone 106 allows the outer sheet 102 to be easily removed from the inner sheet 101 without breaking the structural integrity of the inner 104 weld.

The bottom 104 and top 105 welds are created using heat. The non-heat-sealable material 103 allows the bottom 104 heat seal to only weld the inner sheet 101 to seal and seal the inner bag.

The top heat seal advantageously welds the inner sheet 101 and the outer sheet 102 together, if the inner bag fails to short on top of the outer bag, only the outer bag can be welded by the top heat seal 105.

Alternatively, only one heat seal may be applied to the multi-panel bag 100. The heat seal is applied to the non-heat sealable material area and extends over the non-heat sealable material, thereby sealing the inner and outer panels together over the non-heat sealable region. In this embodiment, the fragile zone is located in the non-heat sealable material area.

-9A paper outer bag may be used if desired. If a paper outer sheet is used, the inside of the paper outer sheet is coated with polyethylene or other thermoplastic at least in the region where the heat seal or top heat seal is located (in the case where bottom or top heat seal is used) to allow heat sealing in the inner and outer sheets above the fragile zone.

In use, the inner bag is filled and the multi-wall bag is sealed as described above. After the heat seals are formed, the multi-wall bag 100 is closed and transported to its destination. The outer bag can be opened along the frangible zone 106, which leaves the inner bag sealed. The outer bag can then be removed while the inner bag remains intact and sealed.

Second example

In the most preferred embodiment, the bag is designed as a base bag, as shown in Figures 2, 3, 3A and 4. It is particularly suitable for packaging milk powder or milk powder derivatives, so that the bag-in-bag solution according to the invention is able to realize a bag, which is suitable for storing 25 kg of powder. For example, the bag can be about. 800-900 mm high, about. 400 mm wide and about. 140-180 mm deep. In the case where the upper part of the bag is used for the first and second welding (the welded part is shown in Figure 3A), the upper part is about. 150 mm high.

The bag has an inner bag surrounded by an outer bag 201 having a base 202 covered by an attachment 203. Before filling the bag, the bag has a non-heat sealable region 205 corresponding to the heat sealable region of the inner bag which forms the first seal to seal the inner bag. After sealing, a frangible zone 206 may be provided along line 206 to separate the first seal from the second seal which may be provided in zone 207 to seal at least the outer bag. Line 208 shows the rear seam of the outer bag.

In this embodiment, it is possible to form the inner and outer bags from different or slightly different plastics, which have different welding start points. When manufacturing, the welding start point of the e.g. polyethylene inner bag is e.g. 10-15°C lower than the welding start point of the outer bag, which may also consist of polyethylene, it is possible to control the application time of the heat sealing rods and the temperature of the heat sealing rods to achieve that the first weld is carried out at a lower temperature than the second. If the application time, temperature and pressure of the first heat sealing set are controlled so that sufficient heat is applied through the outer bag to melt and thus weld the inner bag together, without it permanently sticking to the outer bag, it is thus possible to weld the inner bag at zone 205 and thus have sufficient application time or

- Providing a higher temperature to the second set of welding rods, it is possible to impart sufficient heat to weld the outer bag to the inner bag in zone 207. Both the inner and outer bags can be formed from a multilayer plastic fabric, depending on the material to be packaged.

Figure 3 shows a bag-in-bag according to Figure 2 when it is being filled and sealed. The symbols 205-207 in Figure 2 indicate elements belonging to the zones in which the seals and perforations are made when the bag is closed and sealed after filling, but in Figure 3 the same symbols refer to the location of the seal 205 which is made in the inner bag and the location of the seal 207 which is made in the outer and inner bags and the perforation 206 extending through the outer and inner bags.

Figure 3A shows the sealed bag-in-bag of Figure 3 in cross-section to show the contents 209. The outer and inner bags fit tightly together and are not distinguished in this figure.

Figure 4 shows the bag of Figure 3 with the outer bag partially open so that the second seal 207 can be removed by tearing or cutting along the line of perforations 206.

Figure 5 shows the base of such a bag (as shown in Figures 2-4) where the extension 203 is extended (i.e. longer than extension 203) to provide two extending tabs 214, 215 which do not engage the bottom of the bag, thereby providing handles. A typical length of such a handle means is 35 mm at each end of the extension 213. When the bag of Figure 5 reaches its destination, the top of the outer bag is removed, by pulling or cutting along the perforated line, and the bottom of the outer bag can then be grasped by tabs 214, 115. It is desirable to use a light adhesive to temporarily secure the inner bag to the outer bag in the manufacture of the additional flat-bottomed bag according to this invention.

Figure 6 shows a modified standard length extension 223 in which adhesive is applied to all pockets except 224, 225, such that the extension has finger-grab regions 227 at both ends.

Figure 7 shows an alternative arrangement in which the extension 233 is secured along edges 234, 235 and the extension has two perforations 236, 237 which allow the base to be gripped in a manner similar to that of Figure 5, or alternatively the extension can be pulled, producing two upstanding extension portions which allow the ends of the extension to be torn off along lines 236, 237.

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Figures 8-11 show variations of the multi-sheet plastic bag-in-a-bag system, illustrated in isometric view. In these figures, the outer bag is shown at 801, the inner bag at 802. The first seal 803, which seals the inner bag 802, and the second seal 803, which seals the outer bag, are shown in relation to each other. In Figure 8, the bag has a flush cut closure. In this case, the inner bag is heat sealed at 803, while the outer bag is heat sealed at 804, some distance above 803. The heat seal 804 is made at that point on both the inner and outer bags. Perforations 806 can be cut through and the top of the bag can be removed.

Figure 9 shows a flush cut closure, but in this case both the inner and outer bags 801, 802 are covered with a cap. This is either a polyethylene or paper cap, which may be heat sealed, glued, sewn or otherwise sealed. The cap 807 may be sewn over the bags 801, 802, the perforation 806 extending through both bags.

Figure 10 shows a stepped guide plate top closure welded at 803 and provided with adhesive 809 to the roof 808.

Figure 11 shows a stepped gusset top closure where the outer bag 801 has a gusset 808 that extends to the top of the inner bag 802. The inner bag is heat sealed at 803, with a perforation line 806 extending through the inner and outer bags. Line 806 is above the heat seal 803 and preferably above the lower edge of gusset 808.

Example 3

A double-walled bag having an inner and an outer sheet. The inner and outer sheets are made of non-weldable materials, e.g. the inner sheet is made of polyethylene, the outer sheet is made of woven fabric or paper. At least one end of the inner sheet is closed to form the inner bag. At least one end of the outer sheet is closed to form the outer bag. Heat-sealable ag. is used for the strip towards the open end of the inner side of the outer sheet, or towards the open end of the outer side of the inner sheet. A fragile zone is located at least in the outer sheet, perforated in the outer sheet below the heat-sealable material.

The multi-sheet bag is welded by applying heat to the region of the heat-sealable material below the fragile zone. The inner bag is welded below the region of the heat-sealable material. The outer sheet and the inner sheet are welded together in the region of the heat-sealable material.

Example 4:

Similar to 2: bag-in-a-bag construction. Figure 15 shows a cross-section of such a bag construction in its most basic form, eliminating the use of varnishes. In this arrangement, the inner bag or bag 401 is made of a single-layer plastic, both sides of which are marked with a C. The use of the letters A-E in Figures 15-17 illustrates the use of the different materials. The inner bag 401 is made of a single-layer plastic

is made, while the outer 402 bag is made of two layers of plastic, the outermost layer is made of material A, while the innermost layer of the outer bag is made of B.

In this example, A is typically LLDPE 900-930kg/m3.

Material B is preferably linear LMDPE 935-940kg/m3.

Material C preferably has a value below 926kg/m3, with a lower initial weld value than material B (402, from which the inner surface of the outer bag is made). This solution does not require an oxygen barrier, as it is used to package a stable product.

5,baking salt

Figure 16 shows an arrangement in which the bag 501 consists of two layers of plastic D and E, while the outer bag 502 consists of 3 layers of synthetic nonwoven, composite materials A, B and C. In this example, the letters A-E do not denote the same material as the designations A-C in Figure 15. The letters denote the difference in layers.

In this example, according to the figure below, material A is typically LLDPE with a density of 918 kg/m3. B is LLDPE with a density of 900-930 kg/m3.

Materials C and D LMDPE 935-940 kg/m3.

This material, which forms the inner surface of the inner bag 501, is preferably a material below 926kg/m3, may be LLDPE, VLDPE, with an initial welding point below 107°C.

Its area of use is similar to example 4.

Example 6

This is similar to Example 5 with the addition of an oxygen barrier. The inner bag 601 is constructed of five layers as described below, while the outer bag has three layers, similar to Example 5. In each case, Examples 4, 5, 6 illustrate designs in which the inner and outer bags are made of materials having different initial weld points, thereby minimizing the use of varnishes. By suitably choosing the initial weld values of the different surfaces of the outer and inner bags, it is possible to eliminate the use of varnish. In this example, with reference to Figure 1, material A is typically a linear low density polyethylene (LLDPE) with a density of about 918 kg/m3, preferably. Material B is preferably an LLDPE with a density of 900-930 kg/m3.

Materials C and D are preferably LMDPE with a density of 935-940 kg/m3.

Material E forms the inner surface of the inner bag 601 with a density below 926 kg/m3. Suitable polyethylenes include LLDPE and VLDPE. These are typically materials with an initial weld point below 107°C.

The inner bag also contains an adhesive and an oxygen barrier between layers D and E. Ethylene vinyl alcohol copolymer EVOH is preferably used as an oxygen barrier, 603

-13 sandwiched between two sheets of adhesive 604, such as maleic anhydride granulated polyethylene. Of course, the above are just examples.

In application, the bag-in-bag construction is described in Example 2 with reference to any of Examples 4-6, which is achieved by applying suitable time/temperature/pressure values to the outer surface of the outer bag, e.g. bags 402, 502, 602, with sufficient heat transfer to the inner surfaces 401, 501, 601 of the inner bag, such that the outer surfaces of the inner bag are permanently bonded to the inner surfaces of the outer bag.

Production of plastic bags

In accordance with Example 2, the manufacture of bags will now be described. Example 2 is illustrated in Figure 2, where the inner and outer bags are made of similar plastic, e.g. polyethylene, the difference between the bags being their slightly different initial weld points, such that the inner bag has a slightly lower initial weld point or weld point than the outer bag.

Figure 12 is a schematic diagram of a typical plastic processing machine that processes single or double layer tubular or flat woven fabric. The inner bag is preferably a continuous plastic tube, while the outer bag is a flat woven fabric that is turned around the inner tube. In some cases, the inner bag is made on site from the plastic woven fabric before the outer bag is formed around the inner bag.

Figure 12 shows the following modules:

901 unwinding unit for the outer fabric;

902 uniform woven treatment stations;

903 flexographic printers;

904 hot melt inter-plate carrier unit,

905 shaping units;

906 longitudinal joint unit,

907 unwinding unit for the inner fabric,

908 internal woven heat sealer,

909 rotary cross cutter.

910 tube rotary station,

911 pipe alignment stations;

912 notching and undercutting sections;

913 shows the location of three stations, namely:

(a) tube bottom opening (b) tube bottom drying station (c) tube bottom closing station

914 bottom stacker printer/stacker

- 14915 bottom stacking unwinding unit

916 transport counter and packaging unit for finished bags.

This arrangement produces a bag according to Figure 2, suitable for closing the type according to Figure 8. The inner bag is preferably made of coaxial pipe, the inner surface of which is polyethylene of 926 kg/m3 or less, the initial welding temperature of which is below 107°C. It is supplied in a roll and is located at 907.

Both inner and outer bags can be printed, although it makes more sense to print the outer bag, which is visible during transport, then the outer bag is removed before the contents of the inner bag are used.

The inner bag is preferably at least two layers of polyethylene. The inner layer has a lower initial weld point than the outer layer of the inner bag. Preferably, the inner layer of the inner bag comprises polyethylene with a density below 926 kg/m3 and an initial weld point below 107°C. Suitable polyethylenes are LLDPE and VLDPE.

The outer bag is preferably a flat woven three-layer polyethylene. If the bag contains milk powder, one layer is a light filter layer, such as dark or black plastic, and it is best if the outer bag is the innermost layer.

The outermost layer of the outer bag is preferably white or pastel (for printing purposes) and the outermost layer is preferably a high coefficient of friction plastic, e.g. VLDPE, which provides resistance to slipping. The three layers of the outer bag include a middle layer, which is typically a white plastic, e.g. polyethylene.

The innermost layer of the outer bag is typically linear medium density polyethylene LMDPE, which has an initial weld point 15°C higher than that of the inner surface of the inner bag, so that for example the innermost layer of the outer bag may be 940kg/m3 LMDPE with an initial weld point of 120°C. In most cases it is advantageous if the temperature difference between the initial weld points between the innermost layer of the outer bag and the inner outer surface is minimised, while the initial weld point of the innermost layer of the outer bag is maximised together with the outer layer of the inner bag. A difference of 10°C avoids the use of varnish. Alternatively the initial weld point may be the same, in which case varnish or other non-heat-sealable layer may be applied to the inner surface of the outer bag or to the outer surface of the inner bag.

As shown in Figure 12, the outer layer is unwound, printed and hot-melted, before being fed to the forming table 905, where it is folded around the inner tube to form the outer bag. Meanwhile, the inner tube is unwound from the unwinding unit 907 and sealed at predetermined intervals on the heat sealing unit 908 to form individual bags. Once the outer web is folded around the inner bags, the longitudinal seam of the outer bags is formed on the unit 906 and then the bags are fed to the rotary cross cutter to be cut into individual bags.

- 15 separated, containing both inner and outer bags. These separate bags are then inverted on the rotating unit 910 and then passed to the tube alignment unit before reaching the bottom opening station 912.

Preferably, during the application of the hot melt adhesive at station 904, an adhesive area is applied which will be the inner base portion of the outer bag such that the lowermost portion of the inner bag is bonded to the lower inner surface of the outer bag. This is preferably done on a single face of the inner bag during the formation of the base. This small amount of adhesive helps to secure the inner bag in the outer bag and should be release so that the inner bag falls off when the outer bag is removed at the destination station.

913-915 are locations for preparing the folded base and delivering each outer bag base attachment to each outer bag base in Figures 2-7, resulting in the completed base.

If the inner and outer bags are made of plastic with different weld starting points, then a station for varnish or other non-heat-sealable layers is not required.

Ilxen production line is suitable for producing 15-25kg bottom bags, which are suitable for packaging milk powder, some chemicals and other food products. The dimensions of such bags are 1160 mm ><600 mm.

This type of production line can be used for the production of embodiments 1 and 3, adding a suitable unit to provide either a heat-resistant varnish or a heat-sealing material layer to be applied to the appropriate location of the inner or outer bag. Such a machine can also produce bags with an inner plastic bag and an outer woven bag.

Filling and sealing the bags

The bags produced according to the 2nd-7th brackets can be taken to the end user for use with a filling and sealing machine. For example, a single-head bag filling machine, a multi-head bag filling machine, an end-line or a carousel machine can be used.

The filling machine can be gas-purged or vacuum-packed, depending on the material to be packaged. In some cases, it may be desirable to use oxygen barrier materials.

Once the inner bag is filled, the bags can be heat sealed. It is preferred to send the bags to a neck stretching unit, which stretches and flattens the mouth of the bags. At these stations, the top of the bag is leveled and aligned so that it can proceed to the heat sealing station.

In Figures 3 and 4, the width of the bag is shown larger at the top than at the bottom, in order to highlight the stretching effect before welding.

At the welding station, the first welding rod sets are used and heat is transmitted through the outer bag from the outside, using the appropriate material, temperature and pressure, allowing only the inner bag to be welded as shown in Figure 3. 205

- along line 16. For each plastic bag containing an inner and outer plastic bag, a second set of heat sealing rods applies pressure and heat to the top of the inner and outer bags, allowing heat sealing through four layers of material. The second set of heat sealing rods delivers a higher temperature than the first, resulting in the inner and outer bags being sealed together.

At the same time, the inner and outer bags can be perforated at 206, which is a sufficient distance from the welding line 205. This perforation step is desirable, but not essential, if perforation is used, a heated perforating knife is advantageous to provide welded perforation edges. This welding seals the entry points into the bag and facilitates removal of the inner bag from the outer.

After the bag is filled and sealed, the bag is laid out horizontally, weighed, coded if desired, and preferably placed in a bag flattening unit to flatten the contents and flatten the bag into a rectangular shape.

Advantages

One advantage of the solution according to the invention is that the outer bag can be opened while the inner bag remains uncontaminated and sealed. The inner bag is uncontaminated during transport and can be brought into food hygiene critical areas after the outer bag is removed.

There is no need for materials such as adhesive for the end user of multi-layer flexible packaging when using the double heat-sealed all-plastic combination, as both the inner and outer bags are heat-sealed.

Preferred embodiments of the invention are particularly suitable for packaging and transporting milk powder, milk powder derivatives or other individual food products. After placing the milk powder in a double plastic bag, as seen in the description of embodiment 1 or an outer combination of plastic and paper, as seen in embodiment 2, the milk powder or other food product is placed in a polyethylene inner bag, which can be closed and sealed by heat sealing. This inner polyethylene bag is water and dust tight and thus protects the product from contamination. Prototypes of this invention have been tested on milk powder products and derivatives thereof. The invention is suitable for packaging milk proteins, casein, salt, various food products, food ingredients, pharmaceuticals and other bulk products for which a bag-in-bag solution is required.

The outer bag has two main functions, whether it is made of plastic, e.g. polyethylene or paper. First, it protects the inner bag from damage, and second, it keeps the inner bag clean. In addition, the outer bag can be used for printing and there is an additional advantage if the outer bag is plastic, as it is easier to ensure good quality.

-17printing on the outer bag. It is also possible to use plastic fabrics in order to improve the friction and therefore the slip resistance. The most preferred embodiment of the invention is a double plastic bag, which allows the outer bag to be printed, lightfast, friction and therefore stackable. The use of a double plastic bag, as described above, simplifies the manufacture of the bags and more importantly, it simplifies the handling and closing of the bags and the double plastic bag can be closed in the most preferred form with two sets of sealing bars, in order to seal the inner bag at the first seal and to seal at least the outer bag at the second heat seal, with some form of perforation or other easy opening arrangement between the first and second seals.

Variants

Among the preferred embodiments, reference has been made to a two-panel bag. However, the invention also relates to multi-panel bags or pouches having 3 or more panels, e.g. bag-in-bag-in-bag.

The outer packaging can be sealed with adhesive if necessary after the inner packaging is sealed.

Although the preferred embodiments have been described with respect to the manufacture and use of larger bags, such as those for transporting milk powder or other products weighing 15-25 kg, the invention may be applied to a variety of other sizes of bags or pouches.

For example, sterile liquids may be packaged in small pear-shaped bags, e.g., between 100 and 500 ml, as shown in Figures 13 and 14. In this arrangement, the inner bag 301 is slightly smaller than the outer bag 302, both of which are formed into a similar pear-shaped shape, having a long neck 303. By using a lower weld initiation material for the inner bag than for the outer bag, it is possible to heat seal differently along the neck 303 of the bag, so that the first pair of heat seal rods 304 can be applied to the outer bag 302 towards the bottom of the neck, applying sufficient heat only to the inner bag at the point that results in the heat seal 307, while the heat seal rods 305 can operate at a higher temperature to ensure that both the inner and outer bags are welded together at the line 308.

In the case of a clear separation of heat seals 307 and 308, the heat seals are clearly visible if both packages are transparent, if desired e.g. when transporting sterile liquids, so that it is not necessary to perforate or mark the neck of the bag where to cut between the 307 and 308 seals. The outer bag can be overprinted with a label indicating that it is to be cut between the two heat seals, a colored strip can be placed on the neck of the bag between the two heat seals, with a mark on the outer bag that the bag is

-18The neck must be cut along the colored strip in order to separate the outer and inner bag.

A similar arrangement can be used for vacuum packaging food products such as poultry, cheese, fruit, vegetables, where extended time or travel requires the food to be packaged in a bag-in-bag manner.

Many other variations are possible. For this reason, in the description of Figure 1, only the neck of the package is shown instead of the shape of the bag, the bottom, to emphasize the inventive step of the bag-in-bag solution, which allows the inner bag to be sealed separately from the outer bag, at least during the first heat seal.

1, Table

Option 1 2 3 4 5 6 7 8 9 Reverse varnish J * yf * * y/ * * yf Twin weld J * * * y/ y/ y/ y/ Independent weld. check * y/ * * * k y/ y/ * Perforation J y/ * * * y/ y/ y/ y/ Various weld. ag. * y/ * y/ * * y/ y/ * Low temp. inner cylinder weld.ag. * y/ * * * y/ y/ * High temp. outer plate weld joint * y/ * y/ * * y/ y/ * Incompatible polymers * * * * yf * * k * Duct tape * * yf y/ y/ y/ * * Bottom welding only * * * * * * Heated Perforation Rod * * * * * * * y'' y/

Table 1 shows a number of different options, where the check marks indicate applicable solutions for an option. For example, option 1 uses varnish to prevent welding between the outer surface of the inner plate and the inner surface of the outer plate, while option 2 avoids welding the outer plates with welding materials with different temperature coefficients.

- 19Explanation of table options:

1. Twin weld with bottom weld over reverse varnished non-weldable layer, perforation between two welds. Allows bag production from the simplest plastic films. The closure design is functional due to the applied varnish. Increases the cost of varnish use and has an additional variable for production control.

2. Twin heat seal, caused by the design of the seal, which has unique variables for process control, temperature, residence time and pressure, to seal different seal materials. The bottom seal, which closes the inner tube, has a low temperature seal material on the inside. The top seal is operated at higher settings, for sealing materials that are more difficult to seal. Perforation is between the seals. Lower material costs than option 1 with simplified bag making. Investment requirements for film extrusion equipment are higher.

3. As in cases 1 and 2 or in other cases incompatible thermoplastics are used, e.g. polyethylene for polyamide. Lower welding results in the inner tube being sealed, the upper welding position is not used, but the outer bag is sealed by applying adhesive tape. As in case 1, but with an alternative sealing means on the outer bag. This is useful for the consumer who does not accept the outer bag with perforation lines. It is disadvantageous for the consumer to have to buy additional equipment for applying the adhesive tape.

4. A mixture of 2 and 3, which eliminates the need for the use of varnish in bag production. It has the disadvantages of cases 2 and 3.

5. A variation of case 4 where there is an incompatible polymer on one side of the bag sheet. This can be on the inside of the outer bag and the outside of the inner bag. The total film cost increases.

6. A variation of case 1 that uses the features of case 1 and applies adhesive tape over the perforation line. Requires additional sealing equipment and running costs as in option 3.

7. It is a version of 2, as 6 is of 1.

8. Version 2, which uses a heated welding knife to weld the edges made by the perforation. This should ensure complete exclusion of external contamination.

9. A variation of 1, as 6 is of 2.

Variations can be made from the above examples without departing from the scope of the invention.

Claims (19)

Patent claims: 1. A package comprising an inner bag having an inner and outer surface surrounded by but separable from an outer bag having an inner and outer surface, each bag having a closed bottom and each bag having an open top, characterized in that the inner surface of the mouth of the inner bag has a heat sealable zone and the inner surface of the mouth of the outer bag has (a) a non-heat sealable zone corresponding to the location of the heat sealable zone of the inner bag and (b) a sealable zone between the non-heat sealable zone and the top of the bag, such that the heat seal operation can be performed through the outer bag to create a first seal capable of closing and sealing the mouth of the inner bag without sealing the outer bag in the non-heat sealable zone and the seal operation can be performed on at least the outer bag to create a second seal of the outer bag for sealing and sealing in its sealable zone to enclose the sealed inner bag within the outer bag. 2. Packaging according to claim 1, characterized in that the second seal is applied together in both the inner and outer bags. 3. Packaging according to claim 2, characterized in that the sealable zone of the outer bag is used for heat sealing. 4. Packaging according to claim 3, characterized in that a non-sealable layer is provided on the outside of the inner bag or on the inside of the outer bag in the non-heat-sealable area of the outer bag. 5. Packaging according to claim 4, characterized in that the non-weldable layer is selected from the following group, including but not limited to: solvent-based varnishes, water-based varnishes and silicone dispersions. 6. Packaging according to claim 1, characterized in that the inner and outer bags are made of different materials. 7. Packaging according to claim 6, characterized in that the inner bag is a plastic bag having a lower heat sealing temperature than the material of the outer bag. 8. Packaging according to claim 7, characterized in that the inner bag is made of polyethylene. 9. Packaging according to claim 8, characterized in that at least the inner surface of the outer bag is made of plastic. 10. Packaging according to claim 9, characterized in that the inner surface of the outer bag is formed of polyethylene, which has a higher heat sealing temperature than the material of the inner bag. 11. Packaging according to claim 10, characterized in that the outer bag is formed from polyethylene sheet, or polyethylene-coated paper, or polyethylene-coated woven polypropylene. 12. Packaging according to claim 1, characterized in that the outer bag has a base and the bottom of the inner bag is removably connected to the bottom of the outer bag. 13. Packaging according to claim 12, characterized in that the outer bag has a gripping means at its bottom, so that the user can grasp the bottom of the bag to facilitate removal of the inner bag and its contents from the outer bag. 14. A method of using a package according to claim 1, having an inner bag surrounded by an outer bag but removable therefrom, characterized in that the package is filled by a filling machine until the inner bag is filled to a desired extent, the mouth of the bag is stretched to straighten the inner and outer bags in the first and second sealing zones, the inner bag is sealed along the first sealing zone to form the first seal without sticking to the outer bag, and the inner and outer bags are sealed together in the area of the second sealing zone to form the second seal. 15. A method according to claim 14, characterized in that a frangible zone is provided between the sealable zone of the outer bag and the non-sealable zone of the outer bag. 16. A package according to claim 1, having a filled inner bag which is surrounded by but removable from an outer bag, the inner bag being sealed by a first heat seal, but the outer bag not being heat sealed to the inner bag at that point. -At point 22, the outer bag is closed by a second weld located between the first weld and the top of the bag and a frangible zone is located between the first and second welds, so that in use the outer bag can be removed from the sealed inner bag by tearing or cutting along the frangible zone. 17. Packaging according to claim 16, characterized in that the fragile zone is formed with perforations, both on the inner and outer bags. 18. A method according to claim 17, characterized in that the second seal is removed by tearing or cutting along the fragile zone between the first and second seals and a completely sealed inner bag is removed from the outer bag. 19. Packaging according to claim 16, characterized in that the filled inner package contains milk powder or milk powder derivative.