Two-ply paper bag, a method of manufacturing such a bag, and the use of such a bag for packaging animal food

Abstract

A double-ply paper bag provided in the vicinity of its opening with a strip supporting closure means, said strip forming two substantially facing webs, with only of the two webs being fixed to the inside face of the inner ply of the bag prior to the bag being filled and closed. A method of manufacturing such a bag, and the use of said bag for packaging food for animals.

Description

[0001] The invention relates to the technical field of paper packages for substances containing fats, said substances being in granular or powder form and being sensitive to the environment (light and air), and in particular substances such as pet food or feed for farm animals, dry foods, or pesticides in granular or powder form.

BACKGROUND OF THE INVENTION

[0002] The use of paper for making such packages presents certain advantages: ease of printing making the package attractive for the consumer; cost price lower than that of multilayer or laminated sheets of the kinds described in documents U.S. Pat. No. 6,333,061, WO-A00/77300, WO-A-01/26897.

[0003] The invention relates more particularly to packages of small to medium capacity and having bellows and a rectangular bottom; the capacity corresponding to weights of the order of 500 grams (g) to 15 kilograms (kg), approximately.

[0004] Packages are already known for dry pet foods, in particular for cats or dogs, such packages being made by sticking together two layers of strong paper. Where appropriate, handles, likewise made of paper, are inserted between the two layers of strong paper. Such bags, which generally contain 2 kg to 4 kg, are generally heat-sealed or sealed by stitching after the bag has been filled.

[0005] Such bags present numerous drawbacks.

[0006] A first drawback is associated with the fact that the bag cannot be reclosed in reliable manner, whereas a few kilograms of food can correspond to rations that will last an animal(s) for several weeks. This first drawback gives rise to numerous difficulties:

[0007] the animal is tempted to tip over the package and help itself, which can be dangerous for the animal's health when the food is a high calorie food or has been prescribed by a vet;

[0008] the package allows odors to escape which are not always pleasant for people, but which may be attractive to certain insects that infest the content of the bag and can endanger the health of animals; and

[0009] the food remaining in the bag deteriorates progressively, and can end up being refused by the animal and discarded. The consumer can be mistaken about the cause of this loss of attractiveness, and can wrongly believe that the food is at fault, thus encouraging the user to turn to another brand.

[0010] A second drawback is associated with the practical difficulty involved in opening a bag that has been closed by stitching. Some bags are indeed provided with a stitched closure that includes a loop and chain stitch made using threads of different colors so as to make them easy to distinguish. Nevertheless, many users do not have enough patience to make use of such a sewn mouth in a bag, and they merely tear one of the faces of the bag, e.g. along the stitching, or they cut it open using scissors or a cutter. This second drawback leads to numerous difficulties:

[0011] there is a risk of injury during cutting; and

[0012] it is difficult to provide an opening that is large enough to allow the food to pour out easily, particularly if it is granular form, while also being small enough to enable jury-rigged closure means to be used, for example a clothes' peg.

[0013] A third drawback is associated with the use of two layers of strong paper when making the body of the package. Under the effect of the fat contained in food, the inner sheet of strong paper can become stained, and in the end the outer sheet can also become stained. The package then presents appearance that is unfavorable for being sold. Furthermore, under the effect of stratching by cats or dogs, the package can be punctured or split, leading to the drawbacks mentioned above.

[0014] No solution has yet been suggested for solving all of these problems together without giving rise to an unacceptable increase in the cost price of the bag, and without altering the way it is filled in the factory. In this respect, it should be observed that strong paper bags in the technical field of the invention are conventionally delivered flat (not in rolls or strips), each individual bag being brought beneath a feed duct prior to being closed.

[0015] A few documents of the prior art are described below in order to illustrate problems that have not yet been resolved.

[0016] Document WO-A-97/46461 describes packaging for food, in particular for pet food, constituted by a bellows-type paper bag with handles, the package being provided with strips of loops and a strip of hooks of the kind sold under the trademark Velcro.RTM.. A first strip is placed on the inside face of a first large side of the bag, close to the top free edge of said first large side. The second strip is placed on the outside face of a second large side of the bag, said second large side being provided at its free top edge with a notch placed facing the first fastening strip. A fold line enables the mouth of the bag to be folded down so that the two fastening strips then come to face each other through said notch.

[0017] The embodiment described in document WO-A-97/46461 does not guarantee that the bag is closed in substantially leaktight manner, and it requires numerous additional operations to be performed during manufacture of the bag: the two fastening strips need to be put into place, as do the notch and an additional fold line to enable the mouth to be folded shut. In order to enable a closure flap to be operated successfully, it is necessary for the two portions of the fastening members, the notch, and the fold line, all to be positioned accurately.

[0018] The embodiment described in document WO-A-97/46461 provides no protection against tampering, since the bag is not provided with any indicator of first opening.

[0019] Document FR-A-2 791 040 describes a bellows type bag for packaging bulk substances such as animal feed. The bag can be stored while flat, then filled, and finally closed without requiring any change to the corresponding workstation.

[0020] The embodiment described in document FR-A-2 791 040 presents numerous drawbacks. Firstly, the bag is made using a sheet of synthetic material such as polyethylene. Secondly, the bag has no means enabling it to be reclosed, an emptying opening being formed by a line of perforations placed in a bottom corner of the bag remote from its handle.

OBJECTS AND SUMMARY OF THE INVENTION

[0021] The invention seeks to provide a package based on paper for substances in granular or powder form that are sensitive to the environment (light and air), such as, in particular, pet food or feed for farm animals, said package not presenting the drawbacks of previously known packages and making it possible simultaneously:

[0022] to close the bag, so that its content can be used on several occasions, while reducing any risk of the content of the bag deteriorating;

[0023] to facilitate opening and closing the bag;

[0024] to have an indicator of first opening of the bag;

[0025] to avoid the paper of the bag becoming stained by fats contains in the animal food or in any equivalent substance; and

[0026] to make the bag easier to carry by hand using a suitable handle without any risk of the bag tearing, and in spite of the bag containing a weight of several kilograms of feed or other equivalent substance;

[0027] and to do this without modifying the process whereby such bags are transported, being delivered flat, and without modifying the process whereby said bags are filled.

[0028] For these purposes, and in a first aspect, the invention provides a single-ply or advantageously a double-ply paper bag provided in the vicinity of its opening with a strip supporting closure means, said strip forming two webs that substantially face each other, only one of the two webs being fixed to the inside face of the inner ply of the bag prior to the bag being filled and closed.

[0029] In various embodiments, the bag presents the following characteristics, possibly in combination:

[0030] the inside face of the inner ply of the bag is coated in a polymer material, said coating providing a barrier against fat and reducing the risks of the bag being torn or perforated;

[0031] the strip forming two webs and supporting the closure means is made of a polymer material;

[0032] the web of the strip fixed on the inside face of the inner ply of the bag prior to filling is fixed to said inner ply by heat-sealing or high frequency sealing or ultrasound sealing;

[0033] the web of the strip that is fixed to the inside face of the inner ply and the polymer coating of the inside face of said inner ply are both made of polyethylene and are suitable for being sealed together by applying heat under pressure;

[0034] the closure means comprise a male section and a female section together defining a zip fastener;

[0035] the male and female sections project a little above the top edge of the double-ply of the bag, so as to remain visible; this means that it is not necessary to cut the bag using scissors or a cutter in order to open it;

[0036] the male and female sections extend over a length that is slightly shorter than the width of the bag, so as to make it possible to open only a fraction of the mouth of the bag, as might be required, thus providing a delivery chute, or indeed opening the entire mouth of the bag when a large flow rate is desired;

[0037] the male and female sections are suitable for fitting one within the other and for being separated one from the other by manually actuating a slider;

[0038] prior to first opening, the opening slider is connected to one of the male or female sections by a breakable bridge, thus providing an indicator of first opening; and

[0039] the bag is provided with side bellows.

[0040] In a second aspect, the invention provides a bag as presented above, which bag is closed and filled, the second web of the strip supporting the closure means being fixed to the inside face of the inner ply of the bag.

[0041] In various embodiments, the closed bag presents the following combinations, optionally in combination:

[0042] the two webs of the strip supporting the closure means are sealed together;

[0043] the two webs of the strip supporting the closure means are assembled together via a re-usable adhesive, e.g. as sold by 3M.RTM.;

[0044] the two webs of the strip supporting the closure means are assembled together in peel-apart manner; and

[0045] first separation of the two webs is made visible to the eye by revealing a colored or printed zone that is masked from sight prior to first opening of the bag.

[0046] In a third aspect, the invention provides a method of manufacturing a bag as presented above, the method comprising:

[0047] a step of unreeling stepwise a reel of strips supporting closure means;

[0048] followed by a step of cutting a length from said reel that is slightly shorter than the width of the opening of the bag; and

[0049] then a step of fixing a single one of the two webs of the cutoff length of strip to the inside face of the inner ply of the bag, said fixing being performed while the bag is held open by spacer means such as clamps.

[0050] In various implementations, the method presents the following characteristics, optionally in combination:

[0051] after fixing only one of the two webs of the strip, the spacer means are deactivated and the bag is flattened again for subsequent reopening and filling;

[0052] the bag is filled after only one of the two webs of the cutoff length of strip has been fixed, the spacer means holding the mouth of the bag in the open position;

[0053] once the bag has been filled, the second web of the cutoff length of strip is fixed to the inside face of the inner ply that faces it;

[0054] the two webs of the cutoff length of strip are assembled to each other by heat-sealing;

[0055] the two webs are heat-sealed to each other at least partially at the same time as the second web of the cutoff length of the strip is fixed;

[0056] the two heat-sealing operations are performed hot and under pressure, the strip supporting the closure means, and the coating on the inside face of the inner ply of the bag, both being made of a polymer material such as polyethylene;

[0057] the operations of heat-sealing the second web and of heat-sealing the two webs together are performed on the line for filling the bags, while the bags are being conveyed after being filled; and

[0058] the strip supporting the closure means and the closure means are formed integrally or are assembled together.

[0059] In a fourth aspect, the invention provides the use of a bag as presented above for packaging animal food. As will be understood by the person skilled in the art, a bag as presented above can be used for other purposes, for example packaging animal litter, or dry or low-moisture foods or pesticides in granular or powder form.

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Other objects and advantages of the invention appear from the following description of embodiments, which description is given with reference to the accompanying drawing, in which:

[0061] FIG. 1 is a diagrammatic section view through the top portion of a bag in an embodiment of the invention; and

[0062] FIG. 2 is a plan view of a bellows type bag, in the expanded position, constituting an embodiment of the invention.

MORE DETAILED DESCRIPTION

[0063] The bag 1 is of the double-ply type. In other words, the bag 1 comprises two sheets of paper that are not assembled together over their entire contacting surface areas, but that are fixed together at their edges, in particular at their top and bottom edges.

[0064] In an embodiment, the two sheets are fixed together by adhesive.

[0065] The outer ply or sheet is suitable for receiving printing, and the inner ply or sheet is greaseproof.

[0066] In an embodiment, the inner ply is based on brown kraft paper having polyethylene applied thereto, in particular by extrusion.

[0067] As can be seen in FIG. 2, the bag is provided at the perimeter of its mouth with two webs 2, 3 having outside faces 2a, 3a suitable for being fixed to the inside faces of the inner ply of the bag.

[0068] In an embodiment, the webs 2, 3 are made of a polyolefin-based polymer material suitable for being heat-sealed to the extruded polyethylene of the inner ply of the bag.

[0069] As will be understood by a person skilled in the art, given the nature of the polymer materials used for extruding onto the inner ply of the bag and for extruding the webs 2, 3, it is possible to bond the webs thereto by heating, by ultrasound, or by high frequency.

[0070] The bag is provided with reversible closure means of the zip-fastener type. The male and female sections 4 and 5 of this type of fastener are represented diagrammatically in FIG. 1, it being understood that a wide range of sections are already in existence on the market and are suitable for use in this application. The shapes of the sections 4 and 5 shown in FIG. 1 should therefore be understood as being diagrammatic only.

[0071] A slider 6 enables the zip fastener to be opened and closed by separating the male and female sections 4, 5.

[0072] The bag has means for indicating first opening, such as, in particular, a breakable bridge connecting the slider with one of the sections 4, 5, said breakable bridge being broken on the first occasion that the zip fastener is opened manually.

[0073] Where appropriate, the two inside faces 2b, 3b are suitable for being sealed to each other so as to form a peel-apart assembly, for example by applying a re-usable adhesive on these inside faces, with a message preprinted on the webs being uncovered by such peeling.

[0074] In a variant, the two inside faces 2b and 3b are not suitable for being bonded to each other except via a colored assembly strip using heat-sealing, with separation of the webs 2 and 3 revealing the colored strip so that it can be seen by the consumer.

[0075] Reference is now made more particularly to FIG. 2.

[0076] One of the webs 3 is bonded to the inner ply of the bag while the other web 2 remains free.

[0077] The bags can be delivered while flat to a factory and then filled therein using the conventional technique: the bag is unfolded and conveyed to a filling station where clamps hold the mouth of the bag open. The zip fastener does not impede the flow of substance for packaging into the bag. Furthermore, after being filled, the bags can be closed in a single operation: a heat-sealing operation suffices both to fix the previously free web 2 to the inner ply of the bag, and to fix the two webs 2, 3 to each other, either in peel-apart manner or by heat-sealing.

[0078] The improvements provided to the bag thus have no impact on the structure of the filling and sealing machine.

[0079] The sections 4, 5 extend over substantially the entire width of the mouth of the bag 1, the webs 2, 3 being hidden from view by the two plies of the bag 1.

[0080] The way in which the zip fastener is put into place is described below.

[0081] In a first step, bags are unfolded and taken to a first station by a conveyor. The bag is then opened by engaging clamps inside the bag. The zip-and-slider assemblies are unreeled from a reel, the zip fastener in strip form being provided with zones 7 in which the sections 4, 5 are flattened and bonded together. These zones 7 are substantially uniformly spaced apart at a distance that is slightly shorter than the width L of a broad side of the bag.

[0082] The zip reel is unreeled stepwise and is cut through in each zone 7. A cut-off zip fastener together with its slider is then placed inside the bag and one of the webs 2, 3 is fixed to the inside face of the inner ply of the bag.

[0083] In one implementation, the web is bonded at a temperature of about 230.degree. C. while applying a pressure of about 0.4 Newtons (N) over an area of 15 square millimeters (mm.sup.2), the time required for heat-sealing being about 1.5 seconds (s).

[0084] Once the web has been sealed, the clamps holding the bag open are withdrawn and the bag is flattened again for stacking and palletizing.

[0085] The bag 1 can be provided with handles to make it easier to handle, in particular when it is intended to carry a weight of more than 3 kg. These handles are made of paper, cord, or plastics material, and they are held by adhesive, heat-sealing, or staples, in particular between the two plies of the bag, in conventional manner.

[0086] The bag of the invention presents numerous advantages:

[0087] it can be reclosed so that its content can be consumed on several successive occasions, and the risk of the content of the bag deteriorating is reduced due to the relatively good sealing provided by contact between the sections making up the zip fastener;

[0088] odours cannot escape easily from the substances contained inside the bag;

[0089] indicators are provided for showing whether or not the bag has been opened for a first time;

[0090] the coating on its inner ply serves to prevent the fats contained in the animal food or any other equivalent substance from staining the bag;

[0091] the bag is easy to carry by hand using one or two handles without any risk of tearing, and in spite of a full bag containing several kilograms of food or equivalent substances;

[0092] since the bag is based on paper, recycling presents fewer problems than recycling multilayer structures or laminates, and cost remains moderate;

[0093] use of the bag does not require any transformation of the structure of filling machines; and

[0094] the bag continues to be suitable for being delivered in a flat condition on a conventional pallet.

Claims

1. A single- or double-ply paper bag, the bag being provided in the vicinity of its opening with a strip supporting closure means, said strip forming two webs substantially facing each other, only of the two webs being fixed to the inside face of the inner ply of the bag prior to the bag being filled and closed.

2. A paper bag according to claim 1, wherein the inside face of the inner ply of the bag is coated in a polymer material.

3. A bag according to claim 1, wherein the strip forming two webs and supporting the closure means is made of a polymer material.

4. A bag according to claim 2, wherein the strip forming two webs and supporting the closure means is made of a polymer material, and wherein the web of the strip fixed to the inside face of the inner ply of the bag prior to filling is fixed to said inner ply by heat-sealing or high frequency sealing or ultrasound sealing.

5. A bag according to claim 4, wherein the web of the strip that is fixed to the inside face of the inner ply and the polymer coating of the inside face of said inner ply are both made of polyethylene and are suitable for being sealed together by applying heat under pressure.

6. A bag according to claim 1, wherein the closure means comprise a male section and a female section together defining a zip fastener.

7. A bag according to claim 6, wherein the male and female sections project a little above the top edge of the double-ply of the bag, so as to remain visible.

8. A bag according to claim 6, wherein the male and female sections extend over a length that is slightly shorter than the width of the bag.

9. A bag according to claim 6, wherein the male and female sections are suitable for fitting one within the other and for being separated one from the other by actuating a slider.

10. A bag according to claim 9, wherein, prior to first opening, the opening slider is connected to one of the male or female sections by a breakable bridge.

11. A bag according to claim 1, the bag being provided with side bellows.

12. A bag according to claim 1, said bag being closed, the second web of the strip supporting the closure means being fixed to the inside face of the inner ply of the bag.

13. A bag according to claim 12, wherein the two webs of the strip supporting the closure means are sealed together.

14. A bag according to claim 12, wherein the two webs of the strip supporting the closure means are assembled together via a re-usable adhesive.

15. A bag according to claim 12, wherein the two webs of the strip supporting the closure means are assembled together in peel-apart manner.

16. A bag according to claim 13, wherein first separation of the two webs is made visible to the eye by revealing a colored or printed zone that is masked from sight prior to first opening of the bag.

17. A method of manufacturing a bag as presented in claim 1, the method comprising: a step of unreeling stepwise a reel of strips supporting closure means; followed by a step of cutting a length from said reel that is slightly shorter than the width of the opening of the bag; and then a step of fixing a single one of the two webs of the cutoff length of strip to the inside face of the inner ply of the bag, said fixing being performed while the bag is held open by spacer means such as clamps.

18. A method according to claim 17, wherein after fixing only one of the two webs of the strip, the spacer means are deactivated and the bag is flattened again for subsequent reopening and filling.

19. A method according to claim 17, wherein the bag is filled after only one of the two webs of the cutoff length of strip has been fixed, the spacer means holding the mouth of the bag in the open position.

20. A method according to claim 18, wherein, once the bag has been filled, the second web of the cutoff length of strip is fixed to the inside face of the inner ply that faces it.

21. A method according to claim 20, wherein the two webs of the cutoff length of strip are assembled to each other by heat-sealing.

22. A method according to claim 21, wherein the two webs are heat-sealed to each other at least partially at the same time as the second web of the cutoff length of the strip is fixed.

23. A method according to claim 22, wherein the two heat-sealing operations are performed hot and under pressure, the strip supporting the closure means, and the coating on the inside face of the inner ply of the bag, both being made of a polymer material such as polyethylene.

24. A method according to claim 20, wherein the operations of heat-sealing the second web and of heat-sealing the two webs together are performed on the line for filling the bags, while the bags are being conveyed after being filled.

25. A method according to claim 17, wherein the strip supporting the closure means and the closure means are formed integrally or are assembled together.

26. The use of a bag as presented in claim 1 for packaging foods, for packaging pesticides in granular or powder form, that are dry or have low moisture content.