DE69205214T2 - Resealable bag and method and apparatus for making, filling and sealing the same. - Google Patents

Abstract

A pouch for containing a food product such as shredded cheese, and a novel method and apparatus for forming, filling and sealing the pouch. The method involves providing one or more webs of material to define a pair of walls for the pouch, orienting the web material so that the walls are substantially vertical, with the web having a horizontal longitudinal axis; providing interengageable strips of reclosable fastener material along the web adjacent the lower edges of the walls; forming vertical side seals; filling the pouches through their open bottoms while in inverted orientation; and sealing the bottoms of the pouches. Each of the strips of reclosable fastener material has one or more fastener members thereon. A peelable seal is provided between the product contained in the interior of the pouch and the reclosable fastener members. The peelable seal is preferably formed on the fastener strip material. The peelable seal is sealed prior to filling of the pouches so that product cannot contact the fastener members, and the fastener members are outside of the hermetic seal area. The pouch is preferably provided with a hole above the fastener members to receive a display hanger, and has a line of perforation above the fastener members and above the hole to facilitate removal of the upper portion of the pouch. <IMAGE>

Description

Background of the invention Technical part

The present invention relates generally to packaging for food products and, more particularly, to resealable bags and methods and apparatus for making, filling and sealing such bags.

Background information

It is known in the art that for certain food products, efficient packaging and acceptable shelf life can be achieved by hermetically sealing the product in a package in a make/fill/seal (FFS) operation.

In providing a commercially viable package through FFS operations, several factors must be considered. One factor is that it must be possible for the consumer to open the package without major difficulty. Another factor is that the package must be economical to produce and capable of being manufactured, filled and sealed at a relatively high speed. It is also desirable that the package be durable so that it can withstand the rigors of FFS operation and subsequent transportation and handling without damage or deterioration in appearance.

There has been an increasing demand in recent times for zipper devices or other means of achieving re-closure. One particular package configuration that has been used commercially in recent years is generally rectangular in shape with a re-closable zipper running in a fold along one edge, as illustrated, for example, in U.S. Patent No. 4,589,145. To open the package, the packaging material can be folded along the folded edge. be slit to gain access to the zipper and the zipper is then opened to provide access to the product. Disposing the zipper along a long edge of the package improves access to the interior of the package as compared to disposing the zipper along one of the short edges. Where each package is to contain a stack of sliced product or a relatively bulky article such as a piece of cheese, the stack or piece can be placed on a horizontally oriented web and the web wrapped around the article to form the package described in the above-mentioned Patent No. 4,589,145.

When handling products consisting of several small pieces, such as grated cheese, cereals, etc., it is generally desirable that the package be partially formed into a bag which is open at one end or along one side, the bag being oriented so that the open end or side is at the top of the partially formed bag, and that the product be dispensed into the partially formed bag through the open top or side.

Vertical FFS processes such as those described in U.S. Patent No. 4,874,257 provide one way to address the above factors when packaging food products consisting of multiple small pieces. In the process of Patent No.

4,874,257, the zipper is arranged vertically along one side of the formed package, and the bag is filled by a gravity-induced flow of product downward from a pouring spout.

Another method is illustrated in Patent No. 4,945,714, in which the bags move horizontally as they are made, filled and sealed In Patent No. 4,945,714, the bag is formed in an inverted orientation from a single web having a fold at its lower end and a zipper within the fold. Two potential problems associated with this method are that product may penetrate the zipper and that if the top of the bag is perforated to facilitate opening or pierced to accommodate a hanging device for display, the airtight seal may be lost.

In U.S. Patent No. 4,894,975, a method and apparatus for making a tubing and bag from a thin thermoplastic film is disclosed. The bag is reclosable by a zipper strip that is welded to the film and has a tamper-evident joint between the edges of the film.

One problem that must be addressed with any zippered package as mentioned above is that where the ends of the zippers extend into the sealing area, difficulty in maintaining the airtight seal may occur at high throughput rates due to the increased thickness of the sealing area at the ends of the zipper.

There is a continuing demand for improved packages of the type described above and for improved FFS processes for such packages that take into account the above factors while avoiding the disadvantages of the prior art discussed above.

Summary of the invention

The invention provides a novel bag for containing food products as well as a novel method and a novel device for producing, for filling and sealing the bag in an inverted orientation. The method includes providing one or more sheets of material to define a pair of walls for the bag, orienting the wall material in such a manner that the walls are substantially vertical, the sheet having a horizontal longitudinal axis; providing interlockable strips of resealable fastening material along the sheet adjacent the lower edges of the walls; forming vertical side seals; partially separating the bags from one another by vertically slitting the sheet(s), filling the bags through their open bottoms in an inverted orientation; and sealing the bottoms of the inverted bags. Each of the strips of resealable fastening material has one or more fasteners on it.

According to one aspect of the invention, an airtight peelable seal is provided between the product contained within the bag and the resealable fasteners. The peelable seal is preferably formed as a relatively tight band on the fastener strip material rather than on the wall material. This provides material cost savings compared to coating the entire interior of the bag walls with materials suitable for forming a peelable seal. The peelable seal is sealed prior to filling the bags so that the product cannot come into contact with the fasteners during or after the manufacturing, filling and sealing process(es).

According to the present invention there is provided a method of making, filling and sealing an airtight bag in an inverted orientation, said method comprising:

providing a wall material to define a pair of walls for the bag;

aligning said wall material in such a way that said walls are substantially vertical;

positioning first and second lengths of fastening strip material between said walls, said lengths of fastening strip material having complementary, mechanically interengageable fastening elements thereon;

sealing said lengths of fastening strip material to said walls, each length of fastening strip material being connected to a corresponding one of said pair of walls;

forming a pair of substantially vertical seals connected to said walls so as to define a product receiving pocket having a width determined by the distance between said vertical seals;

Dispensing product downwards into said product receiving pocket to fill said pocket to a certain height;

creating a horizontal seal generally between said walls above said predetermined height; and

separating said bag from said wall material;

characterized in that the method further comprises forming a linear horizontal peelable seal above said fastening elements such that after formation of the product receiving pocket, the peelable seal is located between said pocket and said fastening elements to facilitate separation of the product from the fastening elements during dispensing of the product in to maintain the bag.

It further provides an apparatus for making, filling and sealing an airtight bag in an inverted orientation, said apparatus comprising:

means for supplying a wall material for defining a pair of walls for the bag;

means for aligning said wall material in such a way that said walls are substantially vertical;

means for positioning first and second lengths of fastening strip material between said walls, said lengths of fastening strip material having complementary, mechanically interengageable fastening elements;

means for urging said fasteners into locking engagement with one another;

means for sealing said lengths of fastening strip material to said walls, each length of fastening strip material being connected to a corresponding one of said pair of walls;

means for forming a pair of substantially vertical seals connected to said walls so as to define a product receiving pocket having a width determined by the distance between said vertical seals;

means for dispensing product downwardly into said product receiving pocket to fill said pocket to a predetermined height;

means for providing a generally horizontal seal between said walls above said predetermined height; and

means for separating said bag from said wall material;

characterized in that the device further Means for forming a linear horizontal peelable seal above said fasteners in a sealing region coextensive with said fasteners by applying heat and pressure to said sealing region to form a peelable seal interconnecting said lengths of fastener strip material.

There is also provided a generally rectangular bag for containing a food product, comprising:

a pair of generally rectangular walls, each wall having a top edge, a bottom edge and a pair of side edges;

said walls being joined together by hot-gluing along their lower and side edges;

said bag having a pair of fastening strips attached to opposite inner sides of the upper portions of said walls and extending across the width of the bag between the side edges of the generally rectangular walls; and

said fastening strips having complementary mechanically interlockable fastening elements thereon;

characterized in that said fastening strips have a removable seal extending along the length of said fastening strips beneath said fastening elements; and

that the said bag further comprises:

Means defining a hole through said bag above said fastening elements, and means defining a predetermined fold line above said hole to facilitate opening of the bag by tearing off a upper section.

Sealing of the peelable seal may be performed prior to or at the same time as sealing the fastening strip material to the wall material. Sealing may be performed using a pair of reciprocating sealing rods that apply a predetermined sealing pressure to the sealing area while applying heat thereto. Gas purging techniques may be used to purge the bag with N2 gas during the manufacturing, filling and sealing operations.

The bag is preferably provided with a line of perforations at its top to provide easy-open access to the reclosable fasteners and a hole for receiving a display hanger above the fasteners and below the perforations. With the finished bag in the upright position, the interlocking fasteners are spaced a short distance below the top of the bag.

Further aspects of the invention are disclosed below and in the accompanying drawings.

Short description of the drawings

Fig. 1 is a front view of a bag according to a first embodiment of the invention;

Fig. 2 is a perspective view of the bag of Fig. 1 showing a removable portion of the bag being torn away to provide access to the interior thereof;

Fig. 3 is a sectional view taken substantially along line 3-3 of Fig. 1;

Fig. 4 is a sectional view similar to that of Fig. 3 showing the bag in an opened configuration;

Fig. 5 is a sectional view similar to that of Fig. 3, illustrating a bag according to a second embodiment of the invention;

Fig. 6 is a schematic plan view of an apparatus for making, filling and sealing bags according to the present invention;

Fig. 7 is a front view of the device of Fig.

Figure 8 is a fragmentary schematic plan view of an apparatus according to an alternative embodiment of the invention.

Detailed description of preferred embodiments

The invention is generally realized by a resealable bag and a method and apparatus for producing, filling and sealing the bag.

Figures 1 to 4 illustrate a first embodiment of the invention comprising a bag 10 having first and second generally rectangular walls 12, 14 sealed together along their lower edges 16, 18 and their side walls 20, 22. Closure elements 24, 26 extend across the upper portions of the respective walls.

Each closure element 24, 26 has a substantially planar outer surface 28, 30 which is sealed to its corresponding associated wall. On their inner surfaces, the closure elements have complementary, mutually interlocking zipper profiles 32, 34 which extend horizontally along their entire length, thus making the bag 10 reclosable. A non-peelable top seal 36 is provided along the upper edge of the bag between the upper portions 35, 37 of the closure elements 24 and 26. A plurality of gripping beads 38 extend longitudinally above the zipper profiles 32, 34 at the corresponding Closure elements 24 and 26 between the zipper profiles and the upper seal 36. In the illustrated embodiments, a single pair of gripping beads 38 is formed on each closure element to facilitate manual gripping and separation of the fastening profiles 32 and 34.

Extending longitudinally below and parallel to the zipper profiles is an airtight peelable seal 39. The peelable seal 39 consists of strips of polymeric material 39a, 39b on the respective fastener elements 24 and 26. The strength of the seal 39 is such that it can be easily opened by the application of manual outward force to the fastener elements 24 and 26 by the consumer, but is not susceptible to accidental opening due to normal stresses associated with product storage during the FFS process and subsequent transportation, handling and display. The seal preferably has an opening force of between about 0.68 and about 2.73 kg (about 1.5 to about 6.0 lbs), and more preferably between about 1.14 and about 1.6 kg (about 2.5 to about 3.5 lbs). The peelable seal 39 is substantially impermeable to air as well as to the liquids that may be present in the bag. Accordingly, the location of the peelable seal within the zipper profiles 32 and 34 prevents leakage of contents of the bag into the zipper profiles and seals the locking elements of the zipper against the airtight seal area.

The strips of polymeric material 39a, 39b forming the peelable seal preferably comprise polymeric materials known in the art to be suitable for this purpose, such as one or more of the following materials: Polyethylene/EVA with a VA content between 4 and 22%; Polybutylene; Surlyn; Bynel; Saran copolymer (PVDC); ethylene-acrylic acid copolymer; or methacrylic acid copolymer. As disclosed, for example, in U.S. Patent No. 4,782,951, which is incorporated herein by reference, an airtight peelable seal can be formed between a Saran copolymer coating and an EVA coating.

Each of the bag walls 12 and 14 is preferably made of a suitable laminated material having barrier properties which, when sealed as described herein, provide an airtight seal for the bag. An example of a suitable film for cheese flakes may include a linear low density polyethylene inner layer combined with a polyester or nylon outer layer and a polyethylene middle adhesive layer. A nylon outer layer is particularly useful in the context of Swiss cheese where some degree of permeability to CO2 gas in the package is desirable. The closure elements 24 and 26 are preferably made of low EVA polyethylene. The closure elements may be secured, for example, by a thin layer of Surlyn on each of the closure elements and the walls.

To facilitate support of the bag 10 on a display hanger, a hole 86 is provided in an upper portion of the bag. The hole extends through upper portions of the walls 12, 14 and through the closure members 24, 26, which provide a relatively tough and strong periphery for the hole to support the weight of the bag. As shown in Fig. 1, one or more of the ribs or beads 38 may extend over the hole to further increase the ability of the bag to resist tearing at the hole 86 under rough handling during positioning on and/or removal from a retail display shelf. The arrangement of the Hole above the peelable seal 39 enables the airtight seal to be maintained. Crease lines are formed through the walls 12, 14 and the closure elements 24, 26 immediately below the upper portions 35, 37 of the closure elements to enable the upper portion of the bag to be torn away to provide easy manual access to the gripping beads 38 to separate the zipper profiles 32, 34 and the peelable seal strips 39a, 39b. The crease lines 88 of the illustrated embodiment are in the form of perforations formed opposite one another through the respective walls and closure elements. Locating the perforations 88 above the hole 86 enables the bag to rest on a display shelf without subjecting the perforation lines 38 to transverse tensile loads which can cause accidental tearing.

Fig. 5 illustrates a bag 41 according to a second embodiment of the invention. The bag of Fig. 5 is generally similar to that of Figs. 1-4 in that it comprises a pair of generally rectangular walls 40 and 42 in combination with a pair of closure elements 44 and 46 having interlocking zipper profiles 48 and 50 thereon. Gripping beads 52 are provided above the zipper profiles and a peelable seal 54 extends below. The walls 40 and 42 are sealed together along their lower edges 56, 58 and along their side edges. The bag of Fig. 5 differs from that of Figs. 1-4, however, in that its upper seal 64 is formed immediately between the walls 40 and 42 of the bag rather than between the closure elements. To this end, the closure elements 44 and 46 are spaced below the upper edges of the walls 40 and 42, leaving a peripheral region along the upper edge of each wall for the upper seal 42. As in the embodiment of Figures 1 to 4, the hole for receiving a display hanger is punched through an upper portion of the bag and predetermined crease lines, e.g. perforations 65, are provided opposite one another in the walls immediately below the sealing area 64.

According to a third embodiment of the invention (not shown), the walls of the bag can be made from a single sheet rather than two separate sheets. The bag according to this embodiment is substantially similar to that of Figure 5, except that the bag material is continuous along its upper edge rather than composed of two separate walls connected by a seal, and the bag material creates a tight fit around the upper edges of the closure members 44 and 46. As in the other embodiments, a hole for receiving a display hanger is located adjacent the upper edge of the bag with perforation lines below.

Figures 6 and 7 illustrate a method and apparatus for making, filling and sealing bags in accordance with a preferred embodiment of the invention. As described below, the bags are made, filled and sealed in an inverted configuration. The method will be described with reference to the bag 10 described above with reference to Figures 1 to 4 by describing the sequential steps in making, filling and sealing the bag 10 in its inverted configuration.

In the embodiment of Figures 6 and 7, the material for the walls is provided by a first and a second roll 66 and 68 of a suitable laminated film in sheet form. The material for the Fastening elements are provided via first and second rolls 70 and 72 of fastener strip material. The wall material fed by rolls 66 and 68 comprises sheets 90 and 92 of laminated polymeric material. The fastener strip material comprises a first continuous strip 94 having a zipper receiving profile thereon and a second strip 96 having a male profile thereon.

The first step in the process of Figures 6 and 7 is to fit the complementary zipper profiles 32 and 34 together, i.e., to press the zipper profiles into locking engagement with each other. This step is performed in a zipper assembly station having a shoe 75 with an inner surface 76 configured to hold opposing profiles aligned relative to each other and to bring the fastener strips 94 and 96 into locking engagement with each other as they pass through the shoe.

The next step is to form the peelable seal 39 between the closure members 24 and 26 in a sealing station 78. In the sealing station 78, a pair of horizontally aligned reciprocating heat sealing bars 79 are moved toward each other to apply pressure and heat to the lower portions of the closure members which are to form the peelable seal 39. The closure strip material is advanced in increments so that the strip material is at rest while the heat sealing bars 79 are closed.

The next step involves sealing the outer surfaces of the closure strips 94 and 96 to the inner surfaces of their respective associated wall panels 90 and 92. This is done in an assembly/sealing station 80 in which a second pair of horizontal heat sealing bars 81 is used to achieve the desired seal. The closure strips are positioned along the lower edges of the wall panels while the bag is being formed in its inverted configuration so that they extend across the top of the finished bag in its upright configuration.

The crease line 88 is then formed by a conventional notched perforating wheel on the line at a perforating station 140. Next, the side edges of the bags are sealed by vertical sealing bars 82. In forming the side seals, the sealing bars 82 pinch the closure strips in the areas 84 corresponding to the ends of the closure elements 24 and 26 in the finished bag. The sealing bars provide an impermeable marginal sealing area on each side of the bag being manufactured along the entire vertical dimension of the bag or at least from the lower edges 16, 18 of the walls to the peelable seal 54. The vertical sealing bars 82 preferably include cutting elements for forming vertical slots 139 in the wall panels 90 and 92 extending upward from the lower edges of the respective wall panels to a predetermined height, keeping intact joints 141 of wall material along the upper edges of the wall panels while partially separating the bags from one another.

Since the peelable seal 39 has been formed between the closure elements, the formation of the side seals allows product 100 to be stored in each of the bags produced. The previously unsealed bottom 98 of the inverted bag is held open to provide an opening for receiving the product and the bag is filled to a desired height through a pouring spout 102 with the peelable seal 29 preventing the product from entering the The inverted bag is then purged with N2 or CO2 gas, closed and sealed along its horizontal upper and lower edges by additional horizontally oriented sealing bars 104 and 106. The bag 10 is separated from the preceding and succeeding bags by vertically oriented knives 108 which sever the links 141 and cut the side edges of the bags, whereupon the FFS process is completed.

Where a punched hole 86 is desired, a punching device 142 can be provided at a convenient location on the line. In the device of Figures 6 and 7, the punching operation occurs immediately after sealing the vertical seals of the bag and prior to filling. In other embodiments of the present invention, the order of steps can be varied. For example, in the embodiment of Figure 8, first and second webs 110, 112 of wall material are provided by first and second rollers 114, 116 supported for rotation about vertical axes. Material for closure elements is provided by first and second rollers 118 and 120 of closure strip material. One roller supplies closure strip 122 having a female profile while the other supplies material 124 having a male profile.

In the embodiment of Fig. 8, the lengths of fastener strip material 122 and 124 are joined to their respective associated webs of wall material 110 and 112 at two parallel heat sealing stations 126 and 128. The resulting assembled webs of wall and fastening material 130 and 132 are then fed over vertical guide rollers 134 and 136 to a sealing assembly station 138 where the zipper profiles of the fastener material are joined together locked and the peelable seal is formed in a manner similar to that described above with reference to the embodiment of Figures 6 and 7. The remaining steps of forming the side seal, filling, forming the top and bottom seals and separating the finished bags are as described in the embodiment of Figures 6 and 7.

In a further embodiment of the invention (not shown), the formation of the peelable seal is combined with the process of sealing the fastening strips to the sheets of wall material. This process is similar to that of Figures 6 and 7, except that the sealing station 78 can be omitted and the assembly/sealing station 80 has been modified to apply heat and pressure to perform both sealing operations simultaneously.

From the above description, it will be understood that the invention provides a novel bag and a novel method and apparatus for making, filling and sealing the bag. The invention is not limited to the embodiments described above or to any specific embodiments. The invention is particularly pointed out in the following claims.

Claims (16)

1. A method of making, filling and sealing an airtight bag (10; 41) in an inverted orientation, said method comprising: Providing a wall material (90, 92; 110, 112) for defining a pair of walls (12, 14; 40, 42) for the bag (10; 41); orienting said wall material (90, 92; 110, 112) in such a manner that said walls (12, 14; 40, 42) are substantially vertical; positioning first and second lengths of fastening strip material (94, 96; 122, 124) between said walls (12, 14; 40, 42), said lengths of fastening strip material (94, 96; 122, 124) having complementary, mechanically interengageable fastening elements (32, 34; 48, 50) thereon; sealing said lengths of fastening strip material (94, 96; 122, 124) to said walls (12, 14; 40, 42), each length of fastening strip material (94, 96; 122, 124) being connected to a corresponding one of said pair of walls (12, 14; 40, 42); forming a pair of substantially vertical seals connected to said walls (12, 14; 40, 42) so as to define a product receiving pocket having a width determined by the distance between said vertical seals; dispensing product (100) downward into said product receiving pocket to fill said pocket to a predetermined height; establishing a horizontal seal generally between said walls (12, 14; 40, 42) above said predetermined height; and separating said bag (10; 41) from said wall material (90, 92; 110, 112); characterized in that the method further comprises forming a linear horizontal peelable seal (39; 54) above said fastening elements (32, 34; 48, 50) such that after formation of the product receiving pocket, the peelable seal (39; 54) is located between said pocket and said fastening elements (32, 34; 48, 50) to maintain separation of the product (100) from the fastening elements (32, 34; 48, 50) during dispensing of the product (100) into the pocket. 2. The method of claim 1, characterized in that the peelable seal (39; 54) is made by the step of applying heat and pressure to a sealing area (39a, 39b) of said fastening strip material (94, 96; 122, 124) simultaneously with the step of sealing said lengths of fastening strip material (94, 96; 122, 124) to said walls (12, 14; 40, 42). 3. The method of claim 2, characterized in that the step of applying heat and pressure to said sealing area (39a, 39b) and the step of sealing said lengths of fastening strip material (94, 96; 122, 124) to said walls (12, 14; 40, 42) is performed with a pair of horizontal sealing bars (104, 106) which are reciprocable inwardly and outwardly to apply heat and pressure to said walls (12, 14; 40, 42) and said fastening strip material (94, 96; 122, 124). 4. A method according to any one of claims 1 to 3, characterized in that it further comprises the step of flushing the bag (10; 41) with N₂ gas. 5. Method according to one of claims 1 to 4, characterized in that it further comprises the following steps: Sealing the specified lengths of fastening strip material (94, 96; 122, 124) together beneath said fastening elements (32, 34; 48, 50) to provide an additional seal (36) between said lengths of fastening strip material (94, 96; 122, 124); and Creating one or more predetermined bending points (88; 65) between said additional seal (36) and said fastening elements (32, 34; 48, 50) to facilitate the removal of said additional seal (36) from said bag (10; 41) without removing said fastening elements (32, 34; 48, 50) from said bag (10; 41). 6. The method according to claim 5, characterized in that it further comprises: Forming a hole (86) through said bag (10; 41) below said fastening elements (32, 34; 48, 50). 7. The method of claim 1, characterized in that it further comprises: producing an additional seal (64) between said walls (12, 14; 40, 42) below said first and second lengths of fastening strip material (94, 96; 122, 124), and creating one or more predetermined bend points (65) between said additional seal (64) and said lengths of fastening strip material (94, 96; 122, 124). 8. The method of claim 7, characterized in that it further comprises: creating a hole (86) through said bag (10; 41) beneath said fasteners (32, 34; 48, 50). 9. Apparatus for making, filling and sealing an airtight bag (10; 41) in an inverted orientation, said apparatus comprising: means (66, 68; 114, 116) for supplying a wall material (90, 92; 110, 112) for defining a pair of walls (12, 14; 40, 42) for the bag (10; 41); means for aligning said wall material (90, 92; 110, 112) in such a manner that said walls (12, 14; 40, 42) are substantially vertical; means for positioning first and second lengths of fastening strip material (94, 96; 122, 124) between said walls (12, 14; 40, 42), said lengths of fastening strip material (94, 96; 122, 124) having complementary, mechanically interlockable fastening elements (32, 34; 48, 50) thereon; means (75; 138) for urging said fastening elements (32, 34; 48, 50) into locking engagement with one another; means (80; 126, 128) for sealing said lengths of fastening strip material (94, 96; 122, 124) to said walls (12, 14; 40, 42), each length of fastening strip material (94, 96; 122, 124) being connected to a corresponding one of said pair of walls (12, 14; 40, 42); means (82) for forming a pair of substantially vertical seals connected to said walls (12, 14; 40, 42) so as to define a product receiving pocket having a width determined by the distance between said vertical seals; means (102) for dispensing product (100) downwardly into said product receiving pocket to fill said pocket to a predetermined height; means (104, 106) for establishing a generally horizontal seal between said walls (12, 14; 40, 42) above said predetermined height; and means (108) for separating said bag (10; 41) of said wall material (90, 92; 110, 112); characterized in that the apparatus further comprises means (78, 79) for forming a linear horizontal peelable seal (39; 54) above said fasteners (32, 34; 48, 50) in a sealing region coextensive with said fasteners (32, 34; 48, 50) by applying heat and pressure to said sealing region to form a peelable seal (39; 54) connecting said lengths of fastener strip material (94, 96; 122, 124) together. 10. Device according to claim 9, characterized in that it further comprises: means for sealing said lengths of fastening strip material (94, 96; 122, 124) together beneath said fastening elements (32, 34; 48, 50) to provide an additional seal (36) between said lengths of fastening strip material (94, 96; 122, 124); and Means (140) for creating one or more predetermined folding points (88) to facilitate the removal of said additional seal (36) from said bag (10; 41) without removing said fastening elements (32, 34; 48, 50) from said bag (10; 41). 11. Device according to claim 10, characterized in that it further comprises: Means (142) for forming a hole (86) through said bag (10; 41) below said fastening elements (32, 34; 48, 50). 12. Device according to claim 9, characterized in that it further comprises: means for producing an additional seal (64) between said walls (12, 14; 40, 42) below said first and fastening strip material (94, 96; 122, 124), and means (140) for creating one or more predetermined bending points (65) between said additional seal (64) and said lengths of fastening strip material (94, 96; 122, 124). 13. Device according to claim 12, characterized in that it further comprises: Means (142) for creating a hole (86) through said bag (10; 41) below said fastening elements (32, 34; 48, 50). 14. A generally rectangular bag (10; 41) for containing a food product (100), comprising: a pair of generally rectangular walls (12, 14; 40, 42), each wall having an upper edge, a lower edge (16, 18; 56, 58) and a pair of side edges (20, 22); wherein said walls (12, 14; 40, 42) are connected to one another by hot gluing along their lower edges (16, 18; 56, 58) and side edges (20, 22); said bag (10; 41) having a pair of fastening strips (24, 26; 44, 46) attached to opposite inner sides (28, 30) of upper portions of said walls (12, 14; 40, 42) and extending across the width of the bag (10; 41) between the side edges (20, 22) of said generally rectangular walls (12, 14; 40, 42); and said fastening strips (24, 26; 44, 46) having complementary mechanically interlockable fastening elements (32, 34; 48, 50) thereon; characterized in that said fastening strips (24, 26; 44, 46) have a removable seal (39; 54) which runs along the length of said fastening strips (24, 26; 44, 46) beneath said fastening elements (32, 34; 48, 50); and that said bag (10; 41) further comprises: means defining a hole (86) through said bag (10; 41) above said fastening elements (32, 34; 48, 50), and means defining a crease line (88, 65) above said hole (86) to facilitate opening of the bag (10; 41) by tearing off an upper portion. 15. Bag according to claim 14, characterized in that it further comprises a horizontal upper seal (36; 64) located above said predetermined fold line (88; 65). 16. Bag according to claim 14 or claim 15, characterized in that at least one of said fastening strips (24, 26; 44, 46) has at least one horizontal bead (38; 52) which runs along above said complementary, mechanically interlocking fastening elements (32, 34; 48, 50) and above said hole (86) below said predetermined folding line (88; 65).