US20040022462A1

US20040022462A1 - Multi-layered bag and method of manufacture

Info

Publication number: US20040022462A1
Application number: US10/398,163
Authority: US
Inventors: Michael Markham
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-10-02
Filing date: 2001-10-01
Publication date: 2004-02-05
Also published as: NZ507233A; AU2002211112B2; WO2002028724A2; WO2002028724A8; AU1111202A; WO2002028724A3

Abstract

The present invention relates to a multi-layered bag which includes an inner bag located within the interior of an outer bag, where the outer bag including a first and second region of weakness. The inner bag includes a region of weakness adjacent to the outer bag's second region of weakness. The multi-layer bag has the inner and outer bags sealed closed and together adjacent to the outer bag's second region of weakness. A method of manufacturing such a multi-layered or composite bag is also disclosed.

Description

TECHNICAL FIELD

This invention relates to improvements to packaging. Specifically the present invention may be adapted to provide a multi-layer or multi-wall package or bag, where the outer layer of the bag or package may be removed to leave the inner layer unopened or undamaged. Reference throughout this specification will also be made to the present invention being used to implement a two layer plastic bag but those skilled in the art should appreciate that other applications are also envisioned.

BACKGROUND ART

Packaging is widely used to allow quantities of goods to be transported and stored easily. During transportation and storage packaging can become dirty, damaged, and potentially could be contaminated with harmful or noxious materials. This can make the packaging and the resulting product unattractive to consumers or users and in the case of packaging being damaged or contaminated can also make the product in question unsafe or impractical to use.

To address these problems multi-layered bags have been developed. These bags consist of an inner bag that is surrounded by an outer bag, where the design of the package allows the outer bag to be removed when the product is ready for the consumer or end user. The removal of the outer bag will still keep the inner bag closed and sealed to contain the packaged product.

Preferably such multi-layered bags should be constructed from a single type of material only—such as entirely from paper or entirely from plastic. If different materials are mixed during manufacture this substantially complicates the recycling of the bag as the materials will need to be separated from one another before recycling can occur.

One attempt to provide such multi-layered bag is discussed in New Zealand Patent Application No. 314258. This document discloses a multi-layered bag where the outer bag includes an area that has a higher heat sealing temperature than the adjacent area on the inner bag. This configuration of the bag allows the inner bag to be sealed at one point while keeping the outer bag open at the same point. Other portions of the outer bag may have the same heat sealing temperature as the inner bag which will allow both bags to be sealed closed and together.

This configuration of the bag allows the inner bag to be sealed closed and the product to be packaged at one point then allows the inner and outer bags to be sealed closed and together at a second point above the first seal provided in the inner bag. The opposite end of the bag to the seals discussed above are created using standard manufacturing techniques which employ a separate patch to seal the bottom of the outer bag.

However, the outer bag formed in the above design is relatively difficult to remove. In most instances the entire filled bag must be lifted by the operator to facilitate the removal of the outer bag. The outer bag must be manhandled and tom off the inner bag which can be time consuming and also tiring in case where the filled bag is relatively heavy.

An improved form of packaging and a method of manufacturing same that addressed any or all of the above problems would be of advantage. Specifically an improved type of packaging which could provide a multi-layered bag formed entirely from plastic using existing production machinery, and which included an outer bag which could be easily and quickly removed from an inner bag would be of advantage.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description that is given by way of example only.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided a method of manufacturing a multi-layered bag characterised by the steps of:

(i) forming a first region of weakness in an outer bag, and

(ii) introducing an inner bag to the interior of the outer bag, and

(iii) forming a second region of weakness in the outer bag, and

(iv) forming a region of weakness in the inner bag adjacent to the second region of weakness formed in the outer bag, and

(v) sealing the inner and outer bags closed and together adjacent to the second region of weakness in the outer bag.

According to another aspect of the present invention there is provided a method of manufacturing a multi-layered bag substantially as described above wherein the side walls of the inner and outer bags are connected together adjacent to the outer bag's first region of weakness.

According to a further aspect of the present invention there is provided a multi-layer bag which includes:

an inner bag located within the interior of an outer bag,

the outer bag including a first and second region of weakness,

the inner bag including a region of weakness adjacent to the outer bag's second region of weakness,

wherein the inner and outer bags are sealed closed and together adjacent to the outer bag's second region of weakness.

The present invention relates to a multi-layered bag and a method of manufacturing same. Preferably the method of manufacture used may be a continuous in-line process which will produce a length of joined bags The bags formed may also be open at one end or face to allow for the filling of the product to be packaged. The method of manufacture implemented will be discussed in further detail below.

The present invention incorporates a multi-layered bag that is formed from an inner bag located within an outer bag. Preferably both the inner and outer bags may be formed from plastic material, which will allow an inexpensive multi-layered bag to be produced using well known manufacturing equipment. Reference throughout this specification will also be made to the multi-layered bag formed being made from plastics material, but those skilled in the art should appreciate that other materials may be used to form the same design of multi-layered bags discussed with respect to the present invention if required.

Reference throughout this specification has also been made to the present invention being adapted to provide a multi-layered bag formed from an inner bag and outer bag. The term “bag” as referred to throughout this specification should be taken to mean any form of enclosure or container that may be formed from any type of material but preferably is formed from plastic. Limitations in the volume or capacity of the bag formed by or with the present invention are not considered essential and any particular size, shape, or capacity bag may be manufactured using the present invention.

Preferably the outer bag may surround the sides of the inner bag so that the material of the inner bag will only be visible at the ends of the bag. The outer bag may form a cover-like element for the inner bag and in use may be removed from the inner bag once a packaged product is ready for use or display. The outer bag may form a protective cover for the inner bag where the outer bag is adapted to be easily removed from the inner bag.

In a preferred embodiment the outer bag may include at least a first and a second region of weakness. The region of weakness may be formed in the outer bag by reducing the strength of the material forming that particular region of the outer bag. For example, a region of weakness may be formed through cuts, perforations, or apertures made in a particular region of the outer bag, or alternatively may be formed through thinner or weaker plastics material being used to create that particular area or region of the outer bag. A region of weakness formed within the outer bag may be designed to break or fail under external forces before other areas or regions of the outer bag.

In a preferred embodiment the position of the first region of weakness in the outer bag may vary depending on the type of bag required and the product to be packaged, whereas the position of the second region of weakness may be substantially near one end of the bag in all embodiments. For example, in some embodiments the first region of weakness may be provided either at an open end of the outer bag running along its width, or alternatively may be provided through a line of weakness which runs substantially along the length of the outer bag.

In a further preferred embodiment the outer bag may also include a third region of weakness. This third region of weakness may be provided to simplify or speed up the removal of the outer bag from the main body of the inner bag. A third region of weakness may for example connect the first and second regions of weakness of the outer bag. Such a third region of weakness may be located at any position required on the outer bag, such as for example as a line of weakness running along the length of the bag or alternatively along the width of the bag.

In a further preferred embodiment the outer bag may include only a first and a second region of weakness with each of these first and second regions being located substantially at either end of the resulting multi-layered bag. In such an instance the outer bags second region of weakness may be located adjacent to a closed or sealed end of the multi-layer bag. These regions of weakness may be provided to allow the outer bag to be easily removed from the inner bag containing the product to be packaged.

Reference throughout this specification will also be made to the multi bag being formed in conjunction with the present invention including only a first and a second region of weakness, where each of these regions of weakness are located substantially at the end of the resulting multi-layer bag. However, those skilled in the art should appreciate that other configurations and numbers of regions of weakness may also be formed into an outer bag and reference to the above only throughout this specification should in no way be seen as limiting.

In a preferred embodiment both ends of the inner and outer bags may only be sealed closed and together when the bag is filled with the product to be packaged. Well-known manufacturing technology may be used to provide such seals both during the method of manufacturing the bag and also at the stage when the bag is finally filled with the product to be packaged. The manufacturing method discussed throughout this specification allows a multi-layered bag to be formed with one closed end and one opened end. This allows the bag formed to be packed or filled with material through its open end or face and then sealed closed when filled with the product to be packaged.

In a preferred embodiment the first and second regions weakness in the outer bag may be provided adjacent to the seals provided at either end of the bag. In such an embodiment the regions of weakness may extend across the width of the bag and may be closer to the centre or middle of the bag than either of the seals provided at the ends of the bag.

In a preferred embodiment the inner bag may also include a region of weakness which is located adjacent to or substantially in line with the outer bag's second region of weakness. The single region of weakness formed in the inner bag may be created using substantially the same manufacturing techniques used to form the regions of weakness within the outer bag.

By providing a single region of weakness in the inner bag in line with the second region of weakness in the outer bag this will allow the top of the multi-layered bag to be easily opened by a user pulling the end off the bag in the weakened regions provided adjacent to each other. An end user may open such a multi-layered bag in a single operation at a single point through the regions of weakness provided in line with each other across the width of the bag.

Furthermore, when a bag is to be opened the first region of weakness formed within the outer bag also allows the outer bag to be pulled or moved away from the surface of the inner bag. A break can be made in the body of the outer bag along its first region of weakness which will allow the outer bag to be removed from the inner bag when both bags are opened using the outer bag's second and the inner bag's single region of weakness. This will result in only the portions of the outer bag located between its first region of weakness and the unopened end of the bag remaining in contact with the inner bag.

In a further preferred embodiment the inner bag may also include a seal or closure in its width below or closer to the end of the bag than its single region of weakness. This seal will allow the inner bag to remain closed when its only single region of weakness and the outer bag's second region of weakness are used to form a top of the resulting multi-layered bag. This configuration of the invention will still allow the inner bag to remain closed when the outer bag has been removed from it.

Furthermore, in some embodiments the initial seal or closure formed at an end of the inner bag may be made in a prior bag manufacturing process, or alternatively during the manufacturing process.

For example, in some instances the inner bag may be introduced as pre-made tubular length of material with regular seals spaced across the width of the tube. Alternatively, in other embodiments the seals required across the inner bag may be formed during the manufacturing process itself by (for example) heat sealing equipment. In some instances a heat seal may be applied across a simple tubular stock material before it is introduced into the outer bag material.

Alternatively, in another embodiment an appropriate area of the inner surface of the outer bag may be coated with varnish or lacquer above the region of the inner bag at which the seal is to be located. The lacquer or varnish applied to the outer bag will prevent the inner and outer bags sealing together, but will not prevent the adjacent faces of the inner bag being sealed together to therefore form the closure required.

In addition, the resulting multi-layered bag may also be produced at the end of the manufacturing process with one open end and one closed or sealed end. Preferably the seal provided may be adjacent to and further away from the middle of the bag than the second and single regions of weakness in the outer and inner bags. Such a seal may close and join together both the inner and outer bags at one end while leaving the opposite end of the bag open and ready to be filled by the product to be packaged.

In a preferred embodiment the inner and outer bags may be connected together at one or more points on the side or sides of the resulting multi-layered bag. Such connection may be provided through gluing, adhesive, heat sealing, or stitching the bags together or through any other similar type of connection scheme which can secure together at least one point of the side walls of the inner and the outer bags.

Such a connection or connections may be made to hold the walls of the bags together when the resulting multi-layered bag is filled with the product to be packaged. In this instance the connection or connections provided may make the sidewalls of the multi-layered bag act as a single sheet of material.

In a further preferred embodiment a connection may be provided between the sides of the inner and outer bags at a point or points between the first region of weakness in the outer bag and end of the multi-layered bag adjacent to the outer bag's first region of weakness which is sealed when the bag is filled. This location of the connections means that they will not interfere with the outer bag being removed from the inner bag, as the portion of the outer bag held by the connections is designed to stay in contact with the inner bag after the main body of the outer bag has been removed.

Preferably the present invention also encompasses a method of manufacturing a multi-layered bag substantially as described above. Preferably this may be a continuous in-line manufacturing process in which the raw materials used to form each of the inner and outer bags are supplied to one end of a production line and a continuous length of finished and joined multi-layered bags are produced at the opposite end of the production line.

Preferably such a production line may include a number of stages or components which repeat a particular operation sequentially on a length of plastic material as it is drawn through the manufacturing line. Each stage may repeat its own operation in the manufacturing process once on a length of the plastic material introduced which is the equivalent to the length of the resulting multi-layered bag to be manufactured.

In a preferred embodiment the first stage of such a method of manufacture may involve the production or formation of the outer bag of the resulting multi-layered bag. In this instance a roll of plastic film or sheet may be supplied to a bag making or converting production line to lie out flat and to be drawn along the bed of the production line. At a first stage of such production line a first region of weakness may be formed in the length of the film as it progresses along the line. Preferably the first region of weakness formed may be created through consecutive perforations or cuts being made along the width of the film. These cuts may be made at measured distances from one another so that a single perforation will be provided in each length destined to become an outer bag.

In a further preferred embodiment an additional region of weakness, (which would form a third region of weakness in a resulting multi-layered bag discussed above) could also be formed at this point. For example, in some embodiments a perforated line could be formed along the length of the film destined to become the outer bag which will result in a third region or line of weakness being formed in the outer bag running along its length.

Preferably, once these one or more perforations are made through the outer bag film, the film used to form the bag may be folded over itself to create a substantially “C” shaped length of film. At this stage the inner bag may be introduced into the centre of the “C” shaped folded film so that the outer bag film will enclose the introduced inner bag. Furthermore, the free adjacent edges of the sheet used to form the outer bag may be sealed together to create a continuous length of tubular material which encloses the inner bag material. Those skilled in the art should appreciate that known conversion and manufacturing apparatus, such as a V-former, may be used to fold over the outer bag film and also to introduce the inner bag into the interior of the outer bag.

In a preferred embodiment the inner bag is introduced to the interior of the outer bag sheet as a pre-formed continuous length of tubing. Introducing a length of tubing to form the inner bag substantially simplifies the manufacturing process as it eliminates the need for the film introduced having to be sealed into a tube.

In a further preferred embodiment the inner bag tubing may be introduced into the folded outer bag film with a number of seals already made running across the length of the inner bag tube. The seals may be located at fixed distances from one another along the length of tube introduced to form a sealed end of each resulting inner bag when the final multi-layer is formed. Again this pre-preparation of elements of the inner bag substantially simplifies and speeds up the manufacture of the resulting multi-layered bag.

However, in alternative embodiments the inner bag tubing may not be introduced with a number of seals already made running across the width of the inner bag tube. For example, in alternative embodiments simple tube stock material may be heat-sealed during the manufacturing process to create the seals in the inner bag required. In one instance the inner surfaces of the outer bag material may be coated with a varnish or lacquer compound in the region above the inner bag where the inner bag is to be sealed. A heat sealing bar or similar apparatus may then be applied across with width of the entire composite bag construction. This will seal closed the inner bag, but due to the provision of such a lacquer or varnish compound will not seal the surfaces of the inner and outer bags together.

Reference throughout this specification will also be made to a length of tubular film pre-sealed at positions along its width being introduced into the folded outer bag film to form the inner bag. However, those skilled in the art should appreciate that in other embodiments the material used to form the inner bag may not be introduced in this manner. For example in some embodiments the inner bag may be manufactured or formed from a sheet material at the same time as the outer bag and reference to the above only throughout this specification should in no way be seen as limiting.

Preferably once the tubular length of plastic used to form the inner bag is introduced into the folded length of outer bag sheet, the combined continuous lengths of plastics may be introduced to a sealing component. For example, in one embodiment an edge-sealing unit may be used to seal overlapping edges of the outer bag film to form the outer bag film into a length of substantially tubular plastic. Alternatively the lap sealing component may also be used to achieve the same aim. Any form of sealing component or machinery may be used at this point to form the outer bag film of substantially tubular length that surrounds the corresponding tubular length of plastic that will form the inner bag.

In some embodiments the tubular lengths of plastics discussed above may then be supplied to a post gusseting machine which is adapted to form gussets in the resulting outer bag. Such a machine may be used where the outer bag filled is to be substantially rectangular or square in shape.

However, those skilled in the art should appreciate the use of post gusseting machine with the present invention should be considered optional and in no way essential to the method of manufacture provided.

In a preferred embodiment the combined tubes of plastics material may next have regions of weakness formed within same. Preferably at this point a second region of weakness may be formed within the outer bag adjacent to or in line with a single region of weakness formed within the inner bag. This may be accomplished through using any known form of plastic bag perforation machinery that can, with a single operation, perforate a line through the width of both the inner and outer bag. This will place the second region of weakness of the outer bag substantially adjacent to or on top of and in line with the single region of weakness provided in the inner bag.

Preferably once the second region of weakness has been formed in the outer bag and the corresponding single region of weakness has been formed in the inner bag, a connection or attachment may be made between the sidewalls of the inner bag and the outer bag. Preferably the location of such an attachment may be between the first region of weakness of the outer bag and the area of the length of tubular material which is to form the end of the bag opposite to the outer bag's second region of weakness. Such a connection may be made through, for example, small spots of glue being supplied between the inner and outer bags to connect and attach these regions of the bags together.

As a last stage or step in the manufacturing process both the inner and outer bags may be sealed closed and together adjacent to the second region of weakness formed in the outer bag. The resulting length of joint multi-layered bag may then be cut and separate from one another adjacent to this seal to provide a multi-layered bag which is opened at one end and sealed closed at its opposite end closest to or adjacent to the region of weakness in the inner bag and the second region of weakness in the outer bag.

The applicants believe that the advantages associated with the apparatus and methods described herein include, but are not limited to the following:

(a) The multi-layered bag provides increased product protection during transportation and handling.

(b) As both the inner bag and the outer bag are manufactured from similar materials the bag is easily recycled.

(c) During transportation, the outer bag often becomes contaminated and dirty. With this invention the outer bag can be easily removed prior to the contents of the inner bag being removed or emptied.

(d) One of the innovative features of this invention is the design and positioning of the seals and perforations on the bag. By tearing along the perforations the outer bag can be easily removed without damaging the inner bag. The outer bag can also be removed without the need to lift the entire bag,

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which: [0065]
FIG. 1 shows a side view of a multi-layer bag formed in accordance with one embodiment of the present invention; [0066]
FIG. 2 a side schematic view of the manufacturing line that employs a method of manufacture configured in accordance with a further embodiment of the present invention.[0067]

BEST MODES FOR CARRYING OUT THE INVENTION

FIG. 1 shows a side cross section view of a [0068] multi-layered bag 1 formed in accordance with one embodiment of the present invention.
The [0069] multi-layered bag 1 is formed from or includes an inner bag 2 located within an outer bag 3. The resulting multi-layered bag 1 when immediately removed from a production line has a first open end 4 a that allows product to be packed within the inner bag 2. The bag 1 also includes a second closed end 4 b that has both the ends of the inner and outer bags sealed together and closed. This bag may be supplied to a manufacturer who can fill the bag through its open end 4 a and then seal this end closed themselves to ready the bag for storage or transportation.
The [0070] inner bag 2 also includes an inner seal 5 that closes the inner bag before the end 4 b of the resulting bag. This will allow the bag material present in the end 4 b to be removed without opening the inner bag 5.
In the embodiment shown the [0071] outer bag 3 includes a first region of weakness 6, a second region of weakness 7 and a third region of weakness 8.
These regions of weakness may be formed by perforations or cuts in the outer bag to reduce the strength of these areas when compared with other regions of the [0072] outer bag 3. Furthermore, some variations in design or implementation may be present in such regions of weakness depending on their position on the outer bag. For example the second and third regions of weakness 7, 8 may be formed through simple cuts or perforations in the body of the outer bag, whereas the first region of weakness may form a tear-off strip provided by two sets of parallel perforation lines running along the circumference of the bag.
The [0073] inner bag 2 may also includes a single region of weakness directly underneath and in line with the outer bag's second region of weakness 7. A single region of weakness will provide a substantially weakened area of the resulting multi-layered bag 1 which will allow an end user of the bag to pull the end 4 b directly off the top of the bag. This will expose the inner seal 5 of the inner bag and will still keep the inner bag closed to retain the product it packages. At this stage the majority of the outer bag may be removed from contact with the inner bag using the outer bag's remaining first and third perforated regions 6, 8. The tear off strip formed may be removed to allow the outer bag to be pulled up and off the inner bag.
Furthermore, in the embodiment shown the [0074] third perforation line 8 may also be provided to allow the centre of the outer bag to be split and removed without having to be pulled off the top of the inner bag. Those skilled in the art should appreciate that the provision of a third region of weakness 8 is also an optional or an additional feature as the outer bag, which can easily be removed through the provision of a first and second regions of weakness only.
The [0075] multi-layered bag 1 also includes a set of connection points 9 used to connect the side walls of the inner and outer bags together near the open end 4 a of the bag. These connections 9 may be provided through a small spot of glue, heat seals, or any other similar type of connection means to ensure that the side walls of the inner and outer bags stay together when the bag is to be filled.
FIG. 2 shows a production line used to form the bag discussed with respect to FIG. 1. [0076]
The equipment used includes a hydraulic loading powered [0077] reel unwinder 11 a that is fitted with a roll 12 a of sheet type plastic film 13 a. This film could be co-extruded, blown film, cast film or monolayer blown film using a variety of plastic polyethylene resins or starch based resins, and which could have master-batches, additives or colorants in the formulation. However, the film material is not restricted to these types and could be any material normally used to make a bag.
In the embodiment shown, the [0078] roll 12 a is one metre in diameter and the plastic film 13 a is approximately 1400 mm wide. The film 13 a is placed on the reel unwinder 11 a such that when it is unwound the inside of the outer bag to be formed will be facing up on a film stopper 14 located farther along in the production line.
The production line also includes edge guided [0079] roll dancers 15 which controls unwind speed and film tension. The film 13 a is edge-guided by a steering roll system 16 to maintain correct lateral positioning of the film through the following machinery.
The film passes into the [0080] film stopper 14 which is a machine manufactured by Amplas Inc, of Green Bay, Wis., USA. The film stopper 14 converts the continuous film motion into intermittent motion for the purpose of performing operations that require the film to be intermittently halted before converting the film motion back to continuous.
A set of draw rolls [0081] 17 are used to intermittently advance and stop the film 13 a at predetermined distances to cut a single or twin perforation into the film 13 a. The draw rolls 17 also stop the film at pre-determined distance intervals to punch the edge of the perforation if required. The draw rolls 17 are driven by a servomotor 18 in a time sequence of approximately 50% motion time and 50% rest time.
The production line may also include a [0082] photo scanner 19 to provide a control signal to the servomotor 18 in order to keep the inner film in registration with the perforation operation to be performed on outer film.
Also included is a [0083] dancer 20, which is an accumulating system that accumulates film on the upstream end and pays out on the downstream end, when the draw rolls 17 are stopped. When the draw rolls 17 advance the film, the procedure reverses.
During the stopped portion of the cycle the [0084] film 13 a is punched with a perforation blade operated by an actuating means such as a servo motor or air cylinder 21. This will produce a straight continuous perforation either along the length of the film or transverse to the film direction destined to become the first region of weakness in the outer bag.
If a perforation is required along the length of the outer bag a rotary perforator will be used to make a perforation in the film direction. [0085]
After the perforation is cut, the [0086] film 13 a advances one finished bag length during the next cycle then stops while the next perforation is made.
After the perforation operation is performed on the [0087] outer film 13 a the intermittent motion of the film in the film stopper 14 is converted to continuous film motion by the dancer 20.
The unwinder section of the machine includes a [0088] second unwinder unit 11 b which is fitted with a roll 12 b of tubular plastic film 13 b which could be co-extruded blown film, monolayer blown film, using a variety of plastic polyethylene resins or starch based resins, and which could have master-batches, additives or colorants in the formulation. However, the tubular film material 13 b is not restricted to these types and could be any material used to make a tubular film.
The purpose of this second film of [0089] tubular film 13 b is to form the inner bag. The tubular film 13 b is in continuous form at this stage of manufacture, and will be unwound from the roll 12 b. The tubular film 13 b may have been sealed transverse to the film direction prior to this operation at regular intervals to form the width or cross seal of the inner bag.
An alternative method of sealing the [0090] tubular film 13 b to eventually form the inner bag is to attach a sealing unit (not shown) after the second unwind to seal the tubular film 13 b transverse to the film direction at regular intervals which constitute the length of the inner bag.
After the [0091] outer film 13 a exits from the dancer 20 the inner film of tubular plastic film 13 b is fed in on top of one side of the outer film 13 a.
Both the [0092] outer film 13 a and the inner tubular plastic film 13 b are drawn across a V-Former 22 by a set of nip rollers positioned in front of the V-Former unit.
As both the [0093] outer film 13 a and the inner tubular plastic film 13 b pass across the V-Former, the outer film 13 a is folded across the inner tubular plastic film 13 b in a “C” shape
Both the [0094] outer film 13 a and the inner tubular plastic film 13 b now pass through an edge-sealing unit 23 and across a chilled roller unit. The edge-sealing unit 23 seals the two edges of the outer film 13 a to form an outer tube. This seal is commonly referred to as a fin seal. However, an alternative sealing method known as a lap sealer can be used.
When using the lap seal method, the [0095] outer film 13 a and the inner tubular plastic film 13 b bypass the edge sealing unit and chilled roller unit, and are fed into the lap sealer (not shown). This machine, which is commonly known in the industry as Amplas Model #MLS-60, folds the outer film 13 a into a “C” shape with a slight overlap in the centre of the resulting tube. A sealer (not shown) made up of three floating seal heads in a series followed by a water cooled seal cooling shoe, forms a seal to join the overlapped edges of the outer film to form a tube.
Use of the edge sealing unit and chilled roller unit requires more complex machinery, but the bag manufactured using this method has the advantages of having a better graphics display capability and allows the bag to be constructed of multi-layers of materials which are non-sealable to each other because the inside layer is sealed to the inside layer rather than inside to outside as with the lap sealer. [0096]
Both [0097] continuous films 13 c including the outer film 13 a and the inner tubular plastic film 13 b then bypass a post-gusseting unit 24 and pass into the conventional bag machine 25 such as an Amplas Model M1066-SHW Bottom Seal Bag Machine or similar Bottom Weld machine.
In the bed of the bag machine, various attachments are fitted to perform operations on the [0098] continuous film 13 c in conjunction with the continuous film being sealed and cut to form a bag.
A perforation unit perforates a tear strip along the width of the combined tubular films. This will form the second region of weakness in the outer bag, and the single region of weakness in the inner bag. Tack sealers lightly seal the inner and outer films together to facilitate easy filling of the completed bag. These sealers provide the [0099] connection 9 between the sidewalls of the inner and outer bags.
A sealing unit of the bag machine heat-seals the bottom of the outer bag (see [0100] end 4 b of FIG. 1). The effect of this seal is that the inner and outer bags are sealed together along the length of this seal.
The finished bag is then cut to length and is drawn by drawer rollers on to an indexing table where it is collated awaiting packing. [0101]
Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof. [0102]

Claims

What I claim is:

1 A multi layered bag which includes,

an inner bag located within the interior of an outer bag, the outer bag including a first and second region of weakness,

2 A multi-layered bag as claimed in claim 1 wherein the inner and outer bags are formed from plastic material.

3 A multi-layered bag as claimed in claim 1 or claim 2 wherein the outer bag forms a protective cover for the inner bag, said outer bag being adapted to be removed from the inner bag.

4 A multi-layered bag as claimed in any previous claim formed with one open end or face.

5 A multi-layered bag as claimed in any previous claim wherein the regions of weakness extend across the width of the inner and outer bags.

6 A multi-layered bag as claimed in any previous claim wherein the regions of weakness are formed through cuts or perforations.

7 A multi-layered bag as claimed in any previous claim wherein the first region of weakness of the inner bag runs along the width of the bag adjacent to an open end formed in the outer bag.

8 A multi-layered bag as claimed in any previous claim wherein the second region of weakness of the outer bag is located adjacent to a closed or sealed end of the bag.

9 A multi-layered bag as claimed in any previous claim wherein the outer bag includes a third region of weakness connecting the first and second regions of weakness of the outer bag.

10 A multi-layered bag as claimed in any previous claim wherein the region of weakness within the inner bag is located substantially in line with the second region of weakness in the outer bag.

11 A multi-layered bag as claimed in any previous claim wherein the inner bag includes a seal along its width closer to one end of the bag than the inner bag's single region of weakness.

12 A multi-layered bag as claimed in any previous claim wherein the inner and outer bags are connected together at one or more points along at least one side of the multi-layered bag.

13 A multi-layered bag as claimed in claim 12 wherein connections between the inner and outer bags are made with adhesive.

14 A multi-layered bag as claimed in any one of claims 12 or 13 wherein connections between the inner and outer bags made between the first region of weakness in the outer bag and the adjacent end of the multi-layered bag.

15 A method of manufacturing a multi layered bag characterised by the steps of:

(i) forming a first region of weakness in an outer bag, and

(ii) introducing an inner bag to the interior of the outer bag, and

(iii) forming a second region of weakness in the outer bag, and

16 A method of manufacturing a multi-layered bag as claimed in claim 15 wherein said manufacturing method is completed as a continuous in-line process.

17 A method of manufacturing a multi-layered bag as claimed in any one of claims 15 or 16 wherein the outer bag is initially formed from a sheet of material drawn onto a production line, said sheet being perforated along its width to form a first region of weakness in the outer bag.

18 A method of manufacturing a multi-layered bag as claimed in claim 17 wherein said sheet material used to form the outer bag is folded itself and has its adjacent free edges sealed together after the first region of weakness is formed within said outer bag.

19 A method of manufacturing a multi-layered bag as claimed in any one of claims 15 to 18 wherein the inner bag is introduced to the interior of the outer bag as a preformed length of tubular material.

20 A method of manufacturing a multi-layered bag as claimed in claim 19 wherein a heat sealing element is applied across the width of the combined inner and outer bags to form at least one seal within the inner bag.

21 A method of manufacturing a multi-layered bag as claimed in any one of claims 15 to 20 wherein the inner and outer bags are processed through a post gussetting machine after the inner bag is introduced into the interior of the outer bag.

22 A method of manufacturing a multi-layered bag as claimed in any one of claims 15 to 21 wherein the second region of weakness in the outer bag and the region of weakness in the inner bag are formed through a single perforation operation.

23 A method of manufacturing a multi-layered bag as claimed in any one of claims 15 to 22 wherein after the second region of weakness is formed in the outer bag connections are made between the sidewalls of the inner and outer bag adjacent to the first region of weakness of the outer bag.

24 A method of manufacturing a multi-layered bag as claimed in any one of claims 15 to 23 wherein the continuous length of multi-layered bag is cut into a plurality of separate multi-layered bags after the outer bag has been sealed.

25 A multi-layered bag substantially as herein described with reference to and as illustrated by the accompanying drawings and/or examples.

26 A method of manufacturing a multi-layered bag substantially as herein described with reference to and as illustrated by the accompanying drawings and/or examples.