CA2470975A1

CA2470975A1 - Method and apparatus for making a pre-padded food bag

Info

Publication number: CA2470975A1
Application number: CA002470975A
Authority: CA
Inventors: Dilip Kumar Boal; James Hal Stuckey
Original assignee: Cryovac LLC
Current assignee: Cryovac LLC
Priority date: 2003-06-17
Filing date: 2004-06-15
Publication date: 2004-12-17
Also published as: US20040255556A1; EP1488915A2; AU2004202609A1; EP1488915A3; ATE418445T1; DE602004018573D1; EP1488915B1; NZ533442A

Abstract

There is provided a method for manufacturing pre-padded food-containing bag by perforating across a continuous web of flattened tubular thermoplastic material, forming an opening in a layer of the perforated web, separating the layers of the web, inserting an absorbent the pad through the opening into the inside of the tubular web and making a seal across the tubular web at predetermined lengths to form a bag. The result is that a continuous web of bags containing absorbent pads at discrete intervals. There is also provided an apparatus for carrying out the method.

Description

METHOD AND APPARATUS FOR MAKING A PRE-PADDED
FOOD BAG
BACKGROUND OF THE IIwTVENTION
Field of the Invention The present invention relates to a method and apparatus for making a pre-padded food-containing bag for such products as fresh poultry and meat. More particularly, this invention relates to methods and apparatus for placing an absorbent pad into a food-containing bag made from a web of tubular thermoplastic material.
Description of the Prior Art.
Poultry and meat are frequently sold in transparent plastic bags. Despite the customer being able to see the contents of the bag prior to purchasing, a problem with this type of packaging is that the poultry or meat, no matter how carefully prepared, contains residual blood and other fluids that flow out of the meat after it has been packaged. The blood and other fluids accumulate in the package, thereby detracting from its appearance. In addition, the blood and fluid sometimes leak from the package while the consumer is transporting it home from the market. To counter this problem food bag manufacturers include an absorbent pad in the bag prior to loading the food product. The pad absorbs the exuded blood and fluid into the pad and also enhances the appearance of the finished bagged product. The manual labor associated with placing the absorbent pad in the bag prior to product loading adds to the cost and time associated with this operation.
There are numerous patents directed to thermoplastic food bags with an absorbent pad for packaging food products. One such patent is U. S. Patent No.
4,815,590 to Peppiatt, et al. that discloses a generally rectangular pad attached to the side closest to the bag opening so that the pad is not dislodged when the product is placed in the bag. The pad absorbs blood and other fluids in the meats to keep the package neat and clean and minimize th.e danger of leakage.
An example of a pad for absorbing exuded juices or liquids is shown in U.
S. Patent No. 4,410,578 to Miller. This patent discloses an absorbent pad for use in a bag or tray intended to contain and display fresh food such as poultry or meat.
The absorbent pad includes a mat of liquid absorbing material, and liquid impermeable plastic sheets overlying and underlying the absorbent mat. At least one of the sheets is perforated, and a spacer is disposed between the two liquid impermeable plastic sheets to maintain their separation under the compressive load of the food product resting thereon, such that the ability of the pad to absorb liquids is unimpaired. When a food product is positioned upon the upper sheet of the absorbent pad, any exuded liquids will flow around the pad and enter the pad by capillary action through the perforated openings in the bottom sheet, and the liquids will be held out of contact with the food product minimizing contamination of the product, maintaining its appearance, and improving its shelf life.
There remains a need for a pre-padded thermoplastic food bag. Such a bag would increase packaging rates and reduce labor cost at the packing plant.
BRIEF SUMMARY OF THE I7~1VENTION
It is an object of the present invention to provide a method for making a food-containing bag from a web of thermoplastic tubular material and placing an absorbent pad therein.
Another object of the present invention is to provide an apparatus for making a food-containing bag having an absorbent pad therein from a web of thermoplastic tubular material.
Yet another object of the present invention is the provision of a method for manufacturing pre-padded food-containing bags that have fewer seals than conventional bags.
A further object of the present invention is to provide a pre-padded food-containing bag available in roll form.

It has been found that the foregoing objects may be accomplished in accordance with this invention by providing a method for manufacturing pre-padded food-containing bag by perforating across a continuous web of flattened tubular thermoplastic material, forming an opening in a layer of the perforated web, separating the layers of the web, placing an absorbent pad through the opening into the inside of the tubular web and making a seal across the tubular web at predetermined lengths to form a bag. The result :is a continuous web of bags containing absorbent pads at discrete intervals. There is also provided an apparatus for carrying out the method.
More specifically, in a preferred embodiment, a predetermined continuous length of lay-flat seamless tubular thermoplastic web is unwound from a roll.
The layers of the lay-flat tubular web are perforated at a predetermined length.
The tubular web is fed through a tube opener where the upper layer perforations are separated creating an opening. The tubular web then passes to the inserter where during the seal dwell time, a pair of nip rollers, located at a predetermined distance from the web opening, squeeze the upper and bottom layers together. Air is blown into the opening in an amount sufficient to cause the upper layer of the tubular web to open sufficiently wide for an absorbent pad to be inserted through the opening.
The absorbent pad may have either pressure sensitive or low temperature food grade adhesive attached on one side thereof so that when the excess air is removed from the tubular web the pad is adhered to one of the layers. The tubular web, having the absorbent pad positioned between the layers, passes between laterally adjustable nip rollers to squeeze the air out of the tubing prior to entering the sealer. As the tubular web passes through the sealer a transverse seal is made. The sealer is displaced transversely across the tubular we°b for delimiting a predetermined length serving to define the bag size. The seal may be straight or curved. The seal can be made using an impulse sealer which employs a hot wire.
The bags containing the pads may be wound into a roll and separated when used at the perforations in the bottom layer of the tubular web. There is also provided an apparatus for carrying out the method.
In a second embodiment, the method is similar to the first embodiment described above but differs in that when the tubular web passes through the perforator and opener the bottom layer of the tubular web is perforated and the upper layer is severed or cut. A knife is provided on reciprocating base to cut a slit through the upper layer but not the bottom layer. The perforations in the bottom layer are provided by perforation knife positioned in restraining block and piercing only the bottom layer. To insert the pad it is necessary to open the layers of the tubular web from each other so that air may be blown into the tube to make the tube wide enough to insert the pad. There are several means for separating the layers from each other, such as the eccentric wheel of the first embodiment or vacuum cups. The pad is inserted and the bag is form by sealing as in the first embodiment.
In another embodiment, the flat tubular web is slit along one side and the absorbent pad is inserted at a right angle to the direction of travel of the web and the slit side is heat sealed.
The packaging costs at the consumer level are reduced due to reduction in labor costs associated with manual placement of pads in bag and subsequent increase in productivity by the use of the pre-padded bags. In addition, there are other applications where it is desirable to scavenge oxygen from the bagged product, or add moisture in the bar or anti-microbial pad in the bagged product.
All the above can be accomplished by having a pre-padded bag with the appropriate pad.
Other objects, features and advantages of the invention will become evident from the following description of the drawings and detailed description of the invention.
BRIEF DESCRIPTIOI~T OF THE DRAWINGS
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
FIG. 1 is a front view of a bag-forming machine used to make pre-padded bags according to an embodiment of the present invention;
FIG. 2 is an isometric view of an absorbent pad positioned in a transparent thermoplastic bag made according to the method of this invention;

FIG. 3A-3E show a scheanatic of the method of forming bags with adsorbent pads of one of the preferred embodiments of the present invention;
FIG. 4 is a top view showing the path of the tubular web shown in the method of FIGS. 3A-3E;
FIG. 5 is a top view of the pad inserting section of the method of the present invention showing inline insertion of the pads;
FIG. 6 is a side view of the pad inserting section of the bag-forming machine;
FIG. 7 illustrates another embodiment of the pad inserting section of the present invention showing insertion of absorbent pads at a right angle to the direction of travel of the web;
FIG. 8 shows a side view of an alternative embodiment of the pad inserter taken along line 8-8 of FIG. 7;
FIG. 9A-9E shows the steps used in the method shown in FIGS. 7-8;
FIG. 10 illustrates an alternative transverse seal - a curved seal; and FIG. 11 illustrates the pad having an adhesive attached thereto.
DETAILED DESCRIPTION OF THE INVENTION
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
Referring now to drawings, there is show in FIG. 1 a bag forming machine for making a pre-padded food-containing bag such as the one shown in FIG. 2.
The bag 10 is made from conventional tubular thermoplastic packaging material that is defined by seals 30 and has a fluid-absorbing pad 25 placed therein.
Typically, the thermoplastic material will be polyethylene, although other thermoplastic materials known to those skilled in the art may be used, such as the materials disclosed in U. S. Patent No. 3,741,253 to Brax.

As shown in FIG. 1, the bag-forming machine 100 includes a tubular web supply section 120 and a bag forming section 130. The tubular web supply section 120 includes a pair of cradles 123 mounted on a support base 121 and spaced apart from each other a sufficient distance to accommodate a roll 12 of tubular plastic material. The continuous length of lay-flat seamless tubular web 11 may be unwound from the roll 12 and passed around guide roll 124.
The tubular thermoplastic web 11 is drawn i:n a flattened condition from the supply section 120 to the bag forming section 130 through the nips of tensioning rolls 125, 126 and 127, 128 and around guide roll 129. A pair of drive rolls 131, 132 forming a nip through which the tubular web 11 passes is provided. The tubular web 11 passes around idler roll 133 and is guided by guide rollers 134, 135, 136, 137 to the tube perforator and opener 140.
The tubular web passes through the perforator and opener 140 where the bottom layer of the tubular web is perforated and the upper layer is severed or cut at a predetermined length. A knife 141 is provided on reciprocating base 142 to cut the upper layer. The perforations in the bottom layer are provided by perforation knife (not shown) positioned in restraining block 143 and piercing only the bottom layer. To insert the pad it is necessary to open the layers of the tubular web 11 from each other so that air may be blown into the tube to make the tube wide enough to insert the pad. There are several means for separating the layers from each other to create a bag opening, such as an eccentric wheel (FIG. 3) or vacuum cups (not shown).
The tubular web 11 then lead to the pad insertion section 150 by passing the tubular web 11 around guide roll 155. During the seal dwell time, pair of laterally adjustable nip rollers 151, 152 positioned prior to the sealer 160 and located at a predetermined distance from the opening in tubular web 11 to squeeze the upper and bottom layers together squeezing the air out of the tubular web.
The nip rollers are positioned from the opening 20 at a predetermined distance to correspond with the length between the perforations 17 (FIG. 4). The length of the bag 10 may be varied by changing the distance between the perforations 17 and changing the distance from the opening 20 at the pad inserter to the nip rollers.
Blower 153 blows air into the opening formed in the tubular web causing it to open wide enough to insert an absorbent pad. At the same time a pad 25 passes from pad inserter 154 through the opening in the tubular web where the pad comes to rest inside the tubular web 11. The pad inserter is r~nounted to vertically adjustable support 157.
Sealer 160 is displaced transversely across the tubular web 11 for forming bag 10 at a predetermined a length. The sealer 160 may include a sealing bar which when in sealing position is disposed against restraining bar 162 opposite each other forms a transverse seal (straight or curved heat seal) to form the bag. A
hydraulic cylinder 163 is provided for advancing and retracting the seal bar and restraining bar 162 toward and away from the tubular web 11. It will be understood by those skilled in the art that means other than a hydraulic cylinder, e.g. electric motor, may be used to advance and retract the seal bar. The continuous length of perforated, pre-padded bags then passes to winder assembly 170 where the bags are wound up in a roll 31. When roll 31 is full the continuous length of pre-padded bags is shifted to a second roll. 31' and roll 31 is removed and set up for another winding operation when roll 31' is full.
A method far making the pre-padded bags 10 is shown in FIGS 3A-3E
wherein a roll 31 of individual bags 10 each having an absorbent pad 25 is produced. In FIG. 3A, at station #l, a predetermined continuous length of lay-flat seamless tubular thermoplastic web 11 is unwound from roll 12. The lay-flat tubular web 11 has an upper layer 13 and the bottom layer 14. The tubular web is fed along a path of travel to a perforator 15 and backing bar 16 where the upper layer 13 and the bottom layer 14 of tubular web 11 are perforated at a predetermined length to define the length of the bag (FIG. 4). The perforations are shown by forming line I7 in FIG. 4. In the case of the upper layer 13 the perforation is used to form opening 20 and in the case of the bottom layer 14 the perforation is used to separate each bag for the next succeeding bag.
The perforated tubular web 11 is fed to station #2 shown in FIG. 3B, through a tube opener where the upper layer 13 perforations are separated creating an opening 20. In the embodiment shown in FIG. 3B the opening is provided using eccentric wheel 1S acting against the upper layer 13 of the tubular web and a back up roller 19 to separate at the perforation in upper layer 13. In another embodiment, that shown in FIG. 1, the opening is formed by severing or cutting upper layer 13 and perforating the bottom layer 14.
As shown in FIG 3C, the tubular web 11 next passes to station #3 for pad insertion from the pad inserter 24 where during the seal dwell time pair of nip rollers 21, 22 located at a predetermined distance from the opening 20 to squeeze the upper layer 13 and bottom layer 14 together to close off a section of the tubular web 11 ahead of the absorbent pad 25 so that when the air from air source 23 is blown into the opening 20 the upper layer 13 and the bottom layer 14 of the tubular web 11 are caused to separate sufficiently for absorbent pad 25 to be placed through the opening and into the tubular web. At the same time the absorbent pad 25 is inserted inside the tubular web 11 through the opening 20.
As shown in the enlarged views of FIGs. 5 a.nd 6 the pad 25 is dispensed from a roll of pads 24, such as DRI-LOC~ absorbent pads available from Sealed Air Corporation, and inserted inline in the direction of travel of the tubular web. In FIGS S and 6 only bottom layer 14 of the tubular web is shown for clarity.
Thus, because upper layer 13 is not shown, opening 20 is not shown. In the embodiment shawn in FIG. 5 an indefinite length of pads is fed intermittently at a predetermined time interval from a stock roll 24 a cutting device (not shown) severs the pads from each other. Each pad is then delivered at the predetermined time into the opening 20 of the tubular web. The blowing air assists in pushing the pad into the tubular web. As shown in FIG. 11, The absorbent pad may have either pressure sensitive or low temperature food grade adhesive on one side thereof so that when the excess air is removed from the tubular web 11 the pad is adhered to one of the layers, preferably the bottom layer 14.
The excess air is removed from the tubular web 11 having the absorbent pad 25 positioned between the upper layer 13 and th:e bottom layer 14. As shown in FIG. 3D, station #4, one method of removing the excess air is to pass the tubular web 11 between laterally adjustable nip rollers 26, 27 to squeeze the excess air from the tubing prior to forming the bag.
Bags are then formed at station #5 by converting the tubular web 11 into a continuous series of connected end-seal bags 10, each containing an absorbent pad as shown in FIG. 3E. The bags may be formed by sealing the tubular web across _g_ its width at discrete intervals. As the tubular web 11 passes between sealer 28 and restraining bar 29 a transverse seal 30 is made by heated sealing member 28.
The sealing member 28 is displaced transversely across the tubular web 11 for delimiting a predetermined length serving to limit the size bag 10. The sealing member 28 is moved toward the restraining bar 29 to form a seal 30. The seal may be straight, as shown in FIG. 2 or curved as shown in FIG. 10. It should be understood that any well-known method of sealing is used to form the bags 10.
The bags containing the pads may be wound into a .roll 31. Alternatively, the bags may be folded along the seal and placed in a box until used.
FIGs. 7 and 8 illustrate an embodiment of the absorbent pad dispensing portion of the apparatus showing delivery from a roll 24 of absorbent pads 25 at an angle, preferably a right angle, to the direction of travel of the bottom layer 14 of tubular web 11 intermittent of perforations 17. Far purposes of illustration, the upper layer 13 is not shown. In the embodiment of FIG. 7, the flat tubular web (see FIG. 9A) is slit along one side of the flattened tubular web 11 at slit line 32 (FIG. 9B). The absorbent pad 25 is inserted through the slit line 32 at an angle to the direction of travel of the web 11 as shown in FI(s. 9C. The split side of the tubular web 11 containing the pad 25 is band sealed 33 as shown in FIG. 9D.
Transverse straight seal 30 (FIG. 9E) or curved seal 30 FIG. 10) may be used to complete the pre-padded bag 10.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.
Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

THAT WHICH IS CLAIMED:

1. A method of making a bag from a tube of thermoplastic material comprising the steps of:
providing a continuous length of lay-flat seamless tubular thermoplastic web having an upper layer and a bottom layer;
perforating at least one layer of said tubular web;
forming an opening in said tubular web;
separating said tubular web sufficiently wide for an absorbent pad to be placed through said opening;
placing an absorbent pad into said opening in, said tubular web;
removing excess air from the tubular material, and converting said tubular web into a plurality of end-seal bags whereby a continuous series of bags containing said absorbent pads at discrete intervals is formed.

2. The method according to Claim 1 wherein said converting comprises heat sealing across said tubular web to form a bag.

3. The method according to Claim 2 wherein said continuous series of bags containing absorbent pads is wound onto a roll.

4. The method according to Claim 1 further comprising: adhering said absorbent pad to an inside surface of said tubular web.

5. The method according to Claim 1 further comprising perforating both layers.

6. The method according to Claim 1 further comprising cutting through said upper layer and perforating said bottom layer.

7. The method according to Claim 1 wherein said opening in said tubular web is formed by an eccentric wheel acting against said tubular web.

8. The method according to Claim 1 wherein the layers of said lay-flat tubular web are separated by blowing air into said opening.

9. The method according to Claim 1 wherein said excess air is removed from said tubular web by passing the web through a pair of nip rolls to squeeze the air out of the tubular web.

10. The method according to Claim 1 further comprising slitting said flat tubular web along one side thereof, inserting said absorbent pad at an angle to the direction of travel of said web, and sealing said split side of said web.

11. A method of making a bag from a tube of thermoplastic material comprising the steps of:

providing a continuous length of lay-flat seamless tubular thermoplastic web having an upper layer and a bottom layer;
perforating at least one layer of said tubular web;
forming an opening in said tubular web;
squeezing said upper layer and said bottom layer together to close off a section of the tubular web ahead of an absorbent pad;

blowing air into said opening to separate said upper layer from said bottom layer sufficiently wide for an absorbent pad to be placed through said opening;
placing an absorbent pad into said opening in said tubular web;
removing excess air from the tubular material, sealing said tubular web into a plurality of end-seal bags whereby a continuous series of bags containing said absorbent pads at discrete intervals is formed; and winding said continuous series of bags containing an absorbent pad onto a roll.

12. A bag machine for forming a bag having an absorbent pad therein from a roll of flattened tubular web material comprising:

a tubular supply section comprising a holder for said roll of flattened tubular web material; and a bag forming section comprising;
means for moving said tubular web along a predetermined path;
a perforator for perforating at least on layer of said tubular web;
a means for opening one side of said tubular web;
means for inserting air into said tubular web in an amount sufficient to open said tubular web enough to insert an absorbent pad;
means for delivering and inserting said absorbent pad into said tubular web;
means for removing air from said tubular web; and a sealer displaced transversely across said tubular web for delimiting the length serving to form a bag, said means for delimiting the length forming a bottom seal of said bag.

13. The bag machine for forming a bag according to Claim 12 further comprising means for winding said bags onto a roll.

14. The bag machine for forming a bag according to Claim 12 wherein said sealer for delimiting said length serving to form said bag is a heat sealing wire.

15. The padded bag machine for forming a bag according to Claim 13 wherein said air removal means is a pair of nip rolls through which tubular web passes.

16. The bag machine for forming a bag according to Claim 12 wherein said perforator is a perforation knife set to perforate both the upper layer and the lower layer.

17. The bag machine for forming a bag according to Claim 12 wherein said perforator is set to perforate one of the layers and a knife is provided to cut a slit in the other layer.

18. The bag machine for forming a bag according to Claim 12 wherein said means for opening said tubular web is an eccentric wheel acting against said tubular web.

19. The bag machine for forming a bag according to Claim 12 wherein said means for removing excess air from said tubular web is a pair of nip rolls to squeeze the air out of the tubular web.