NO882443L - PACKAGING PACKAGING AND PROCEDURE FOR PREPARING SUCH A PACKAGING. - Google Patents

Description

For many years, people have eaten popped corn kernels as a snack product. Such snack products are usually prepared by storing the corn kernels in a net-like container placed over an open fire, by placing the corn kernels in a covered pan placed on a lit kitchen stove burner, or by placing the kernels in a container with electric resistance heating elements after which current is passed through the resistance heating elements. In all these methods, the corn kernels are heated until they pop. Although these corn popping methods have been used to a large extent, people have long searched for a more convenient and faster way to produce popcorn. In addition, it is preferable to be able to pop corn in a container that does not need to be cleaned but can instead be thrown away after use.

However, the need for quick and easy preparation of foodstuffs is limited to popcorn, but consumers have also tried to cook many different foodstuffs quickly and conveniently. As a result, microwave ovens have become increasingly popular for preparing food.

Those familiar with microwave technology have been aware for some time that microwaves heat materials selectively. Materials that absorb microwaves (ie lossy materials) are heated by microwaves, while materials that reflect microwaves or are transparent to them are not heated to any significant extent. Many foods are heated very efficiently by microwaves as they contain moisture which has a high loss factor. The microwaves are consequently absorbed by the moisture in food, which is thus rapidly heated. This understanding of the technical basis for microwave heating has found application in the production of popcorn. More specifically, it has been discovered that moist heat in the corn kernels can be stored as they absorb the microwaves. As the grains' moisture is heated, it evaporates, eventually causing the kernel to pop.

Manufacturers of microwave ovens or of dishes for microwave ovens have tried to capitalize on the microwave's ability to pop corn by producing devices made of plastic, glass or ceramics for popping corn. Such devices are described in US Patents 4,156,806, 4,158,760, 4,299,160, 4,335,291, 4,435,628, 4,477,705, 4,496,816, 4,532,397, 4,542,271, 4,563,561 and Japanese Patents 56-12928 and 56-56534. In addition, US pattern registration Nos. 255,535 and 255,536 relate to a decoratively designed device for making popcorn with microwaves. Although such durable devices are used for the production of popcorn with microwaves, they are relatively expensive and therefore cannot be thrown away after use. Instead, such devices must be cleaned before they are used again.

An alternative to durable devices are cardboard containers such as those described in US Patents 4,036,423, 4,038,425, 4,248,901, 4,260,101, 4,277,506, 4,279,933, 4,448,309, 4,453,665, 4,553,010, 4,584 .202 and 4,586,649. Similar containers can also be made of plastic as described in Japanese Patent Document No. 60-234562. Although such containers can be thrown away after use, the material and manufacturing costs are still quite high. Moreover, such containers are usually bulky and are therefore difficult to store compactly.

Another way to package popcorn is to use bags that can be subjected to microwave treatment. US patent document 3,582,363 deals with a cellophane bag for packaging popcorn which can be subjected to microwave treatment, while the more commonly used paper bags are described in US patent documents 3,851,574, 3,973,045, 4,461,031, 4,493,685 and 4,596,713.

Such bags conventionally include a pair of closed ends and between these runs a front wall, a back wall and side walls which connect the front and back walls. On the front or back wall, a seal runs between the ends and this is formed by connecting the side edge surfaces of a material web from which the bag is made. When this bond is established, the web is transformed into an elongated tube which is cut across into a shorter tube which is then closed at one end so that bags are formed. The bags are then filled with the prescribed ingredients through the open end of the bag. Then this open bag end is usually sealed by heat and pressure which causes a layer of adhesive material on the inside of the bag to stick to itself. Such bags can either be of the vertical or horizontal type.

During microwave popping, the bags used for packaging the corn kernels will expand, and at a predetermined internal pressure in the bag, one end of the bag will open and enable ventilation. After the popping is finished, the venting end of the bag can be opened completely to enable the consumer to either eat the popcorn directly from the bag or to pour it out of the bag into a serving bowl.

Although the packaging of popcorn for microwave popping in such paper bags has achieved some success, this technology is also not without problems. More specifically, such bagged grains may not pop, but burn or become chewy when exposed to microwaves. Paper bags are also often stained by oil or fatty substances that have been injected into the bag. It is also difficult to serve popcorn from such bags and it has consequently been necessary to use a serving bowl which must be cleaned afterwards. With lying bags there are serving problems since the popcorn often falls out of the open end, while standing bags can easily tip over and it is difficult to see what is in them. When the consumer touches the inside of such a bag, he gets oil on his hands, arms and sleeves from the contact with the oil on the inner surfaces of the bag. In addition, the consumer risks being burned when they grab hold of the bag's ventilation end and tear this end open.

A number of solutions to these problems have been developed.

US Patent 4,219,573 prescribes placing an insulating layer between the bottom of the microwave oven and the bag to increase the percentage of popped grains.

U.S. Patent Nos. 4,450,180 and 4,548,836 and Japanese Patent No. 60-234562 (all of which are collectively referred to hereinafter as the ("Golden Valley Foods Patents") reduce the percentage of popped grains by using a bag with different sized pleats that forming two tubes of different sizes.The popcorn and oil or substances are added only to the small tube that rests on the bottom of the oven.

According to US patent 4,283,427, a chemical susceptor pocket containing a combination of a dissolved material of inorganic salt from group IA and IIA metals and a polar solvent of the dissolved material is incorporated in food cartons (not in bags). From the start, the susceptor pocket absorbs microwaves, but when the food being heated reaches a certain maximum temperature, the susceptor pocket becomes permeable to microwaves to avoid burning (scalding).

US Patent 4,571,337 prevents popped grains from becoming chewy by using a stand-up bag with a top that is heat-sealed so that a central portion of the top remains closed until opened by a predetermined pressure in the bag. One takes advantage of the fact that there are only two layers (ie the front wall and the back wall) along the center strip at the top of the bag to form a relatively weak seal at the center strip compared to the seal at the rest of the top of the bag, where the front and back walls lie in line with the folded side walls to form four layers, i.e. the front wall, the back wall and the two sections of the folded side wall).

US patent 4,292,332 prevents paper bags from being stained by providing a synthetic resin layer on the inside of the bag. According to US patent 4,571,337, the inner side of the bag is also provided with an inner layer of a polyester film to prevent staining.

US Patent 4,292,332 also relates to a microwave pop cereal product filled in a bag for instant serving which is obtained by subjecting the bags to a further manufacturing step by perforating the bag. After the popping is finished, the bag can be torn open along the perforations to transform the bag into a serving container. The perforations also have a pressure relief function. However, such packaging is more expensive due to the additional manufacturing step. Furthermore, it is difficult to perforate accurately and uniformly, so that the bags are consistently ventilated at the desired bag pressure. Furthermore, such perforations are often weakened or broken during shipment and this alters the ventilation properties or may destroy the bag contents due to exposure to the atmosphere. When converting the packaging into a serving bowl, the consumer must place their fingers against the perforations and bend downwards, risking their fingers being burned by hot steam escaping from the bag. Furthermore, after the bag is finally opened, it does not completely store the popcorn, and as a result, some of the contents will spill out of the ends of the bag.

There is thus still a need for further improvements to microwave popcorn products that are packaged in bags.

It has been shown that popcorn can be popped with microwaves in a bag that can act as a serving bowl after popping to avoid the problems of serving popcorn from vented bags. It has also been shown that such a serving bowl feature can be incorporated into bags without modifications to or additions to the existing bag's structure, without the risk of spillage of the popcorn ingredients, without exposing the consumer to the risk of burns while achieving an accurate and uniform ventilation. In addition, flavorings and other additives can be more easily distributed over the popped corn through the opened back seal.

All these advantages can be achieved using a seal on the front or back wall of the bag which extends longitudinally between the ends of the bag for ventilation. The wall seal's ventilation pressure is selected and regulated during the bag's manufacture by varying the amount and composition of adhesive used to form the seal, as well as the pressure and temperature the seal is exposed to when it is manufactured. As a result, when the packaged microwave popcorn product is exposed to microwaves, the bag will expand while the wall seal is sufficiently strong to open only when a predetermined pressure is achieved. The bag is then ventilated through the seal until the corn popping with microwaves is finished. Otherwise, the bag ends remain closed.

After the popcorn package is removed from the microwave source, any unopened portion of the vent wall seal is sufficiently weak that a consumer can open it completely by pulling it with their hands without tearing the bag elsewhere. When the wall seal is fully opened, hot steam will escape through the widened opening without the risk of burning the consumer's

hands, which are otherwise placed at a distance from the wall when the bag

is opened. When the bag is opened, part of it, which previously formed the wall seal and now defines the opening, moves upwards and encloses the popcorn. Although the wall seal enables ventilation underneath

the kernel popping and opening during conversion to a serving bowl, the seal is strong enough to be kept closed during shipping, handling and preparation for popping the corn kernels.

As an alternative to ventilation through the back seal, the microwave popcorn product according to the invention can be designed so that the ventilation can take place through one of the ends of the bag. When the popping is finished, the bag's back seal can be pulled open to transform the bag into a serving bowl.

The advantages achieved with the packaging according to the invention are further enhanced by the fact that the bag is made of a laminate with an outer layer of paper, an inner layer of grease-proof paper and a susceptor such as a layer of metallized and selectively demetallized polyester film between the inner and the outer layer and which is only attached to the part of the bag that rests on the bottom of the microwave oven. Other similar laminates can also be used, such as an outer paper layer with an inner layer of a thermoplastic polymeric barrier material. In this alternative embodiment, a susceptor is also preferably used within the paper layer, while the layer of polymeric barrier material consists of polyester or the like. Further improvements can be achieved by using corn kernels which are selected so that 60-75 kernels have a total mass of 10 g.

With the exception of the relative strengths of the bag seals, the microwave popcorn product according to the invention is usually produced in accordance with conventional methods.

First, separate webs are made of the material such as paper for the outer layer of the bag, grease-proof paper for the inner layer of the bag and a susceptor such as a polyester film (e.g. polyethylene terephthalate) which is initially completely metallized and then selectively demetallized. Such metallized films are described in US patent 4,258,086. 4,267,420, 4,553,010 and 4,592,914. Demetallizing polyester film is also well known. Generally, the polyester film is metallized and then selectively demetallized so that the light transmission of the metallized film is 35-75%, preferably 50-65%. The three material webs are then joined using conventional techniques to produce a laminate with two layers (ie paper and grease-proof paper) in some places and three layers (ie paper, metallized and selectively demetallized polyester film and grease-proof paper) in others places.

Instead of using greaseproof paper as the inner layer of the bag, a layer of thermoplastic polymeric material can be used. In such cases, a similar lamination procedure is used.

The laminate is then folded and sealed lengthwise using known techniques for producing a tubular web which is then cut into tubular segments of smaller lengths. Such processes can be carried out using conventional bag making machines such as that manufactured by Holweg S.A. and Windmoeller&Hoelscher GmbH. With such equipment, the strength of the longitudinal wall seal can be adjusted by varying the sealing pressure or temperature and/or the amount or composition of the adhesive used.

Then one end of each of the tubular segments is sealed in a conventional manner. E.g. the end of the bag can be subjected to heat and pressure so that an adhesive material which is arranged as a coating on the inside of the pipe at this end sticks the pipe walls together at this point. The sealed tube end can then be folded across the bag against either the front or back wall, an adhesive being applied to maintain this fold.

After one end of the bag has been sealed, grains of corn and then hot liquid oil or fat mixed with salt and any coloring and/or flavoring substances can be injected into the bag. Colorants, flavorings (eg, butter flavoring, brown sugar flavoring, caramel flavoring, maple flavoring, cheese flavoring alone or with jalapeno, nacho or pizza seasoning, barbeque flavoring, meat flavoring, or mixtures thereof) or salt may also be added to the bag. If a lying bag is used, it is preferred to keep the introduced materials in a place which is essentially at the same distance from the ends of the bag. This is done by again folding the sealed bag end over the front or back wall of the bag. The bag can be folded anywhere between 25 and 40% of the distance between the bag ends. Instead of folding the bag before filling, it can be pinched in one place during filling and folded later. After the ingredients are introduced into the bag, the hot melted oil or fatty substance cools and solidifies with the corn kernels and the other ingredients.

After filling, the open end of the bag is closed in the same way as the other end of the bag. E.g. the open end of the bag can be exposed to heat and pressure so that an adhesive which is arranged as a coating on the inner walls of the tube connects the walls. This end can then be folded across the bag and against the front or back wall, applying an adhesive material to preserve the fold. By sealing the ends in this way, the wall seal will open and provide ventilation while the ends remain closed.

After sealing, the top of the bag is folded over the front or back wall so that a compact packaging is formed. Again, the upper end of the bag can be folded between 25 and 40% of the distance between the ends of the bag depending on how the lower end is folded. In order to increase the shelf life of the product, it is preferred to wrap the filled and sealed bag in a plastic pocket made of a material commonly used for such purposes (e.g. polypropylene film with a heat-sealing layer applied as a coating on or co-extruded on one or two surfaces ).

Alternatively, the product's shelf life can be increased by freezing the packaged product.

Particularly preferred formulations of the injected ingredients in the bag according to the invention are listed in table 1 (natural aroma formulation) and table 2 (butter aroma formulation).

The invention will be described in more detail below with reference to the drawings, in which: Fig. 1 is a perspective view of the back wall of an unfilled bag according to the preferred embodiment of the invention and where the wall seal has been opened.

Fig. 2 is a plan section along the line 2-2 in fig. 1.

Fig. 3 is a partial plan section of an alternative embodiment of an unfilled bag according to the invention and where the wall seal is open. Fig. 4 shows a partial plan section of another embodiment of an unfilled bag according to the invention with an open wall seal and shows an inner layer of a polymeric material. Fig. 5 shows a perspective view of the front wall of an unfilled bag according to the invention. Fig. 6 shows in cross-section a bag according to the invention where one end is sealed and filled with corn kernels and fat or oil. Fig. 7 shows a cross section of a bag along the line 7-7 in fig. 6. Fig. 8 shows a perspective view of a bag filled with corn kernels and fat or oil and where both ends are sealed. Fig. 9 shows a perspective view of a bag according to the invention containing corn kernels and oil or fat, and where both ends are sealed and placed in a microwave oven. Fig. 10 shows a perspective view of a bag made in accordance with the invention and containing grain that has been popped with microwaves. Fig. 11 shows a cross-section of a bag along the line 11-11 in fig. 10. Fig. 12 shows a perspective view of a bag according to the invention with popped corn kernels and which a consumer is about to open. Fig. 1 shows a perspective view of the back wall 18 of an unfilled bag 10 according to the invention and where the wall seal 28 has been opened. In addition to the back wall 18, the bag 10 is provided with a front wall 16 and a pair of inwardly folded, pleated side walls 20, all of which extend between an open upper end 12 and a closed lower end 14. The lower end 14 is folded inwards and attached to the back wall 18 with an adhesive at the lower seal 22. The folded side walls 20 project inwards towards each other between the front wall 16 and the rear wall 18 but a central strip 24 of the front wall 16 and the rear wall 18 lies between the innermost points of the folded side walls 20.

During the production of the lower seal 22 (and the upper seal 4 6 which is discussed below) an adhesive is applied to both bag surfaces so that when the upper end 12 and the lower end 14 are folded over and sealed, a seal is formed both inside in the bag and on the outside of this to ensure that these bag ends remain sealed. The adhesive is preferably dried so that it is not activated before it is brought into contact with heat with a view to sealing.

Fig. 2 shows a side section taken along the line 2-2 in fig. 1. At the back wall 18 and folded side walls 20, the bag 10 is formed by two layers, an outer paper layer 38, and an inner layer of grease-proof paper 40. The front wall 16 is also arranged with a susceptor 3 6 between the respective outer and inner paper layers 38, 40. The susceptor 36 can be made of a metallized and selectively demetallized polyester. Although many different metals and polyester films can be used to produce the susceptor 36, a polyester film of polyethylene terephthalate is preferred, while the metal is preferably aluminum. If a bag made of paper with an inner layer of polyester film is used, the metallic part of the susceptor may optionally consist of stainless steel or a mixture of metals. The susceptor can also be supplied in the form of a metallized polyester film bound to paper or cardboard which is cut to a suitable size and arranged between layers of paper or other laminating materials. Optionally, a susceptor material can be printed on one of the paper layers or on another lamination material.

In the preferred embodiment of the invention, the back seal 28 is formed by first bonding the back seal surface 30 and then the back seal surface 32 with an adhesive 34. As shown in fig. 2, the back seal 28 is formed by bonding the inner layers of greaseproof paper 40 of the first and second back seal surfaces 30, 32. The strength of the back seal 28 can be regulated by varying the composition or amount of adhesive. The adhesive is preferably a thermoplastic polymeric material such as a vinyl acetate emulsion. The amount of glue is regulated to modify the band width of the adhesive 34 so that a narrower band of adhesive enables ventilation at a lower pressure than a wider band of adhesive. Fig. 3 shows a partial side section of a less preferred embodiment of an unfilled bag according to the invention and where the wall seal 328 is open. The back seal 328 is formed by first bonding the back seal surface 330 and then the back seal surface 332 with an adhesive 334. In this embodiment, the outer paper layer 338 of the first back seal surface 330 is attached to the inner grease-tight paper layer 340 of the second back seal surface 332. Fig. 4 shows a partial plan section of another embodiment of an unfilled bag according to the invention where the wall seal is opened and exhibits an inner layer of polymeric material 442. The back seal 428 is as in the preferred embodiment according to fig. 2, formed by bonding the inner surfaces of first back sealing surface 340 and second back sealing surface 432 to each other. However, the bag formed from a laminate comprising a paper layer 428 and an inner layer of a thermoplastic polymeric barrier material 442 instead of using an adhesive to bond these layers together, is provided with a back seal 438 by bonding the layers of barrier material 442 to the first back seal surface 430 and the second back sealing surface 432 to each other using heat and pressure. In this embodiment, the paper layer 438 does not need to be grease-proof, and the layer of polymeric barrier material 442 is a polyester film laminated on the paper so that the paper and the polyester are bonded to each other. Optionally, the laminate in fig. 4 in general be sealed in the manner shown in fig. 3, with either the layer of polymeric barrier material 442 of the first back seal surface 430 bonded to the paper layer 438 of the second back seal plate 432, or with the layer of polymeric barrier material 442 of the second back seal surface 432 bonded to the paper layer 438 of the first back seal surface 430. Fig. 5 shows a perspective view of the front wall of an unfilled bag according to the invention where the back wall seal is open. As the drawing shows, the susceptor 36 is arranged within part of the front wall 16. The ratio between the width of the susceptor 36 across the bag 10 and its length which runs partly between the

upper end 12 and the lower end 14, are usually approx. 1:1.0-1;1.4, preferably approx. 1.0-1.5. The front wall 16 and the back wall 18 across the upper end 12 have a width that is usually approx. 1.3-1.5 and preferably approx. 1.4 times as large as the width of each of the side walls 20 which are folded into the bag 10.

Although fig. 1-5 shows a bag with an open back wall seal, this serves exclusively for illustrative purposes, as the back seal 28 has already been closed for a long time at the time the bag is manufactured.

Fig. 6 shows a cross-sectional view of a bag according to the invention with a sealed end and filled with corn kernels and oil or fat, while Fig. 7 shows a cross-section of the one in fig. 6 showed bag along the line 7-7. Before corn kernels 42 and oil or fat 44 are filled in, the bottom of the bag 10 is folded over the bag towards either the front wall 16 or the back wall 18, so that the ingredients do not sink to the bottom of the bag. As shown in fig. 7, the back seal 28 is produced in accordance with the preferred embodiment where the inner paper layers 40 in the first back seal surface 30 and the second back seal surface 32 are joined by means of an adhesive 34.

In the same way as shown in fig. 7, the side walls 20 are folded and pleated inward so that the front wall 16 and the inwardly folded part of each pleated side wall in the vicinity of the front wall 16 delimit a tube which extends lengthwise and which corresponds to what is delimited by the back wall 18 and the inwardly folded part of each pleated side wall in near the back wall 18. How a bag forms these tubes is discussed more fully in the Golden Valley Foods patent documents. As fig. 7 also shows, the cross-section of the bag 10 is essentially filled with corn kernels 42 and oil or fat 44.

Fig. 8 shows a perspective view of a lying bag 10 which is filled with corn kernels and oil or fatty substances and where both ends are sealed. The seal 4 6 at the upper end is formed in the same way as the bottom seal 22 in that the upper end 12 is folded over the wall 18 and glued together with the upper seal 46. Optionally, the upper end 12 (as well as the lower end 14) can be closed by heating and compressing the front and back walls 16, 18 to join the inner surfaces at the upper end 12. The upper end 12 can then be folded over the wall 18 and then attached. The inner surfaces of the upper end can be made to adhere to each other by applying an adhesive to the surface or by providing the bag with an inner layer of polymeric material which adheres to itself under exposure to heat and pressure, as shown of fig. 4. According to another alternative, simply heat seal the end without folding or further binding. When the ventilation is to take place through the back seal 22, however, the end seals must be stronger than the back seals 28, so that the back seal 28 opens during the corn popping with microwaves, while the seals at the upper end 12 and the lower end 14 remain closed. Such a result can be achieved by using a stronger binding adhesive for the end seals than for the back seal.

The filled bag 10 shown in fig. 8 not only has a lower folded end 47 but also the upper folded end 49 which is folded against the back wall 18. The lower folded end 47 and an upper folded end 49 can be folded over that part of the bag for reasons of compact packaging and shipping 10 which contains unpopped corn kernels 22 and oil or fat 44, and which is usually equidistant from the ends 12 and 14. In this folded position the bag can be frozen and/or sealed in a pocket (not shown) made of plastic, (f .eg polypropylene film) to increase the product's durability during storage.

As shown in fig. 9, the sealed bag filled with corn kernels, solidified fat and oil, etc. is placed on the bottom 50 of the microwave oven 48. The bag is placed with the front wall 16 containing the susceptor 36, closest to the bottom of the oven 50. In addition, the lower folded end 47 and the upper spread folded end 49 away from the part of the bag containing the corn kernels 42 and solidified fat or oil 44. After the bag has thus been placed on the bottom 50 of the microwave oven, the oven door (not shown) is closed, and the microwave oven is turned on for approx. 5 minutes. Then the grains start to pop as the moisture in each grain evaporates. This evaporation of moisture causes the bag to expand so that the back wall 18 moves upwards and away from the front wall 16. In addition, the inwardly folded, folded side walls 20 move outwards so that each of the folded parts including each fold moves away from each other.

Instead of placing the bag on the bottom of the oven 48 itself, the bag can rest on a raised support which is supplied as an accessory to the oven or as an element in the packaging.

Fig. 10 shows a perspective view of a bag according to the invention containing popped corn 56, while Fig. 11 shows a cross section of the bag according to fig. 10 taken the line 11-11. As the microwave popping of the corn kernels continues, the evaporation of the moisture causes the corn kernels to pop and the evaporated moisture expands the bag 10. The expansion causes the pressure in the bag 10 to rise until it forces the wall seal 28 to open. The bag opens at a pressure of 150-286 mm (2.5-4.5 inches) water column, preferably 216 mm (3.4 inches) water column. The breaking of the wall seal 28 where the first and second back sealing surface 30 and 3 2 are joined together forms the back sealing opening 52 through which steam V from the interior of the bag escapes. As can be seen from fig. 10, the lower seal 22 and the upper seal 46 remain closed as these are stronger than the rear seal 28. The rear wall 18 is provided with a pair of bag opening tabs 54 at a distance from the bag sealing opening 52. When a clamping force S is applied to these tabs as well as to the corresponding parts on the side walls 20 and a pulling force P of 1.25-3.63 kg (2.75-8.0 pounds) (preferably 2.04 (4.5 pounds)) is exerted, any unopened portion of the back seal 28 is opened so that the back seal opening 52 expands. Such a complete opening of the seal 28 under the application of the force P can occur

without tearing the bag elsewhere.

Fig. 12 is a perspective view of a bag 10 according to the invention with popped corn kernels and which has been opened by a consumer. When the consumer places his thumbs T on these tabs and his index fingers I against the side walls 20 below these tabs, squeezes the bag between his thumb and index fingers and pulls the tabs apart with the pulling force P, as shown in the figure, the opening 52 expands as a result of the first and second rear sealing surface 30, 32 are pulled apart. As the pulling continues, the upper edges of the rear sealing rafts are raised respectively from position 30' to 30 and from position 32<*> to 32, so that the popcorn 56 is enveloped and not spilled. Although the vapor V still escapes from the opening 52 there is little or no risk of the consumer burning their hands due to the distance from the opening 52.

Instead of venting through the back seal 22, the upper end 12 can be allowed to open during popping as is usually the case, to enable ventilation of the bag 10. After the popping is finished, the back seal 28, which remained closed during the opening, is pulled up as shown in fig . 12 to convert the bag into a serving bowl. Such ventilation of the upper end 12 is produced by heat sealing the ends with adhesive material inside the bag and without folding or further sealing of this end. Again, the longitudinal rear seal is designed to open at a tear force of 1.25-3.63 kg (2.75-8.0 pounds), preferably 2.04 kg (4.5 pounds).

Claims (45)

1. Maize grain packaging that is suitable for popping with microwaves, characterized in that it comprises a bag with a pair of closed ends and between which a front wall and a back wall protrude as well as side walls that connect the front and back walls, and the bag is designed to contain a number of corn kernels and oil or fat, and a seal on the back wall extending between the ends of the bag, which is formed by bonding side edge surfaces of a material from which the bag is made, and which has sufficient strength to first open and allow the bag to be vented during the popping of the corn kernels after it a predetermined pressure in the bag is achieved. 2. Packaging in accordance with claim 1, characterized in that both side edge flaps which are connected to form the seal are made up of the bag surfaces which are arranged to adjoin the corn kernels. 3. Packaging in accordance with claim 2, characterized in that the side edge rafts are connected with a thermoplastic polymeric material. 4. Packaging in accordance with claim 1, characterized in that the seal is formed by bonding one side edge surface with the bag surface which is designed to border the corn kernels, to the other side edge surface which is the bag surface which is designed to face away from the corn kernels . 5. Packaging in accordance with claim 1, characterized in that the side edge rafts are connected with an adhesive. 6. Packaging in accordance with claim 1, characterized in that the side edge rafts are connected with a thermoplastic polymeric material. 7. Packaging in accordance with claim 1, characterized in that the bag is a laminate with an outer layer of paper, an inner layer of paper and a susceptor layer between the inner and outer paper layers. 8. Packaging in accordance with claim 7, characterized in that the susceptor layer is only located in the front wall. 9. Packaging in accordance with claim 8, characterized in that the susceptor layer is a metallized and selectively demetallized polymer film. 10. Packaging in accordance with claim 7, characterized in that the inner layer of paper is a grease-proof paper. 11. Packaging in accordance with claim 1, characterized in that the bag is a laminate with an outer layer of paper and an inner layer of polymeric material. 12. Packaging in accordance with claim 1, characterized in that the side walls are folded inwards and folded in such a way that the front wall and the folded inward part of each folded side wall near the front wall delimit a longitudinally extending tube, while the back wall and the adjacent folded inward part of each of the folded side walls defines a different tube. 13. Packaging in accordance with claim 12, characterized in that the tubes are essentially the same. 14. Packaging in accordance with claim 1, characterized in that the bag is a lying bag. 15. Packaging in accordance with claim 1, characterized in that the ends of the bag are folded over themselves and closed by gluing. 16. Packaging in accordance with claim 1, characterized in that the closed ends of the bag are sealed with sufficient strength so that they remain closed during the microwave popping. 17. Packaging according to claim 1, characterized in that the predetermined pressure is 159-286 mm (2.5-4.5 inches) water column. 18. Packaging in accordance with claim 1, characterized in that after ventilating the bag, the seal can be completely pulled up with a force of 1.25-3.63 kg (2.75-8.00 pounds). 19. Maize grain packaging which is suitable for popping with microwaves, characterized in that it comprises a bag with a pair of closed ends and between these protrudes a front wall, a back wall and side walls which connect the front wall and the back wall, and the bag is arranged to accommodate a number of corn kernels and oil or fatty matter, and a seal on the back wall that extends between the ends of the bag, the seal being formed by joining the side edge surfaces of a material from which the bag is made, and where the seal after popping is sufficiently weak that a consumer can pull it apart by hand without tearing the bag pieces elsewhere, so that the bag is provided with a single opening formed by the side edge fins and converted into a serving bowl where the popped corn can be removed through the opening. 20. Packaging in accordance with claim 19, characterized in that the connected side edge surfaces which form the seal are made up of the surfaces of the bag which are arranged to adjoin the corn kernels. 21. Packaging in accordance with claim 20, characterized in that the side edge rafts are connected with a thermoplastic polymeric material. 22. Packaging in accordance with claim 19, characterized in that the seal is formed by a side edge surface, which is the bag surface which is designed to border the corn kernels, being bonded to another side edge surface which is the bag surface which is designed to face away from the corn kernels. 23. Packaging in accordance with claim 19, characterized in that the side edge rafts are connected with an adhesive. 24. Packaging in accordance with claim 19, characterized in that the side edge rafts are connected with a thermoplastic polymeric material. 25. Packaging in accordance with claim 19, characterized in that the side walls are folded inward and folded so that the front wall and the folded-in part of each folded side wall near the front wall delimit a longitudinally extending tube which is equal to that defined by the rear wall and the adjacent folded-in part of each of the folded side walls. 26. Packaging in accordance with claim 19, characterized in that it further comprises tabs on the back wall of the bag, the tabs being arranged so that consumers can grasp them with their fingers and pull them apart so that the seal is opened completely after the corn kernels have been popped to form the only opening. 27. Packaging in accordance with claim 19, characterized in that the consumer can pull the seal apart after popping with a tearing force of 1.25-3.63 kg (2.75-8.00 pounds). 28. Packaging according to one of the preceding claims, characterized in that it contains a number of corn kernels and oil or fat. 29. Packaging in accordance with claim 28, characterized in that the number of corn kernels and oil or fatty substances essentially fills the bag across. 30. Packaging in accordance with claim 28, characterized in that the said number of corn kernels and the oil or fatty substances are located at an equal distance from the ends of the bag. 31. Packaging in accordance with claim 28, characterized in that the oil or fatty substance is solidified. 32. Packaging of maize grains suitable for popping with microwaves, characterized in that it comprises a lying bag with a pair of ends that are folded over themselves and closed by gluing, and between these protrudes a front wall, a back wall and side walls that connect the front and back walls, the side walls being folded inward and seamed, and the bag is a laminate with an outer layer of paper, an inner layer of grease-proof paper, a susceptor only between the inner and outer layers of the front wall, and where the folded-in part of each folded side wall near the front wall, together with the front wall, defines a longitudinally extending tube which corresponds to what is bounded by the back wall and the adjacent folded-in part of each of the folded side walls, a number of corn kernels and solidified oil or fatty substance which fills the bag crosswise and which are generally at the same distance from the ends of the bag, a seal on the back wall, which extends between the ends of the bag, the seal being formed by bonding with an adhesive at the side edge rafts of a material from which the bag is made, both of the bonded side edge surfaces being the bag surfaces that border the corn kernels, and the seal is sufficiently strong to open and allow venting of the bag during the popping of the corn kernels at a pressure in the bag of 159-286 mm (2.5-4.5 inches) water column, while the ends remain closed, and tabs on the back wall of the bag where any unopened portion of the seal is sufficiently weak after popping, and the tabs are arranged so that they can be grasped by consumers and pulled apart with a force of 1.25-3.63 kg (2.75-8 .00 pounds) to open the seal completely after the corn kernels are popped, so that the bag is provided with a single opening defined by the edge surfaces and converted into a serving bowl from which the popped corn can be removed through the opening. 33. Method for producing a corn grain packaging suitable for popping with microwaves, characterized in that a produces an elongated web of material suitable for forming a bag, closes the side edges of the web to form a longitudinally extending tube and a longitudinal seal, cutting the longitudinally extending tube transversely to form a plurality of shorter individual tubes with an open first and second end, closing the first end of each of the shorter individual tubes to form a plurality of open-ended bags each comprising a front wall, a rear wall and side walls extending between the first and second ends, fills a number of corn kernels and oil or fats in each of the bags, and closes the other end of each of the bags, the longitudinal seal on each of the bags having sufficient strength to first open and allow the bags to be vented during the popping of the corn kernels when a predetermined pressure is achieved in the bags, and any unopened portion of the seal is sufficient weak enough after popping that consumers can pull it apart by hand after the corn kernels are popped, without tearing the bag elsewhere, so that the bag is provided with a single opening defined by the edges and converted into a serving bowl from which the popped corn can be removed through the opening. 34. Method in accordance with claim 33, characterized in that the ends of the bag are closed by folding each of the ends over the bag towards the front or back wall and an adhesive is applied where the ends are in contact with the wall. 35. Method in accordance with claim 33, characterized in that the closed first end is further folded over the bag and against the front or back wall before a number of corn kernels and oil or fats are filled in. 36. Method in accordance with claim 35, characterized in that the filling of a number of corn kernels and oil or fats comprises injecting the number of corn kernels into the bag through the second end while the first end is sealed and folded over the bag, and the oil or fat is injected through the first end into the bag containing the corn kernels. 37. Method in accordance with claim 36, characterized in that the oil or fatty substance is further allowed to cool and solidify in the bag. 38. Method in accordance with claim 37, characterized in that one further folds the other closed end over the bag after the closure of the other end to form a compact packaging for the purpose of dispatch and storage. 39. Method in accordance with claim 33, characterized in that both of the connected side edge surfaces to form the seal include the bag surfaces that border the corn kernels. 40. Method in accordance with claim 33, characterized in that the side edge rafts are connected with a thermoplastic polymeric material. 41. Method in accordance with claim 33, characterized in that the seal is formed by one side edge surface, which is the bag surface bordering the corn kernels, being bonded to another side edge surface, which is the bag surface facing away from the corn kernels. 42. Method in accordance with claim 33, characterized in that the side edge rafts are joined with an adhesive. 43. Method in accordance with claim 33, characterized in that the side walls are folded inwards and folded in such a way that the folded-in part of each folded side wall near the front wall, together with the front wall, delimits a longitudinally extending tube which corresponds to what is delimited by the back wall and the adjacent folded-in part of each of the folded side walls. 44. Method in accordance with claim 43, characterized in that the corn kernels and the oil or fatty substance mostly fill the bag across. 45. Method according to claim 33, characterized in that the predetermined pressure is 159-286 mm (2.5-4.5 inches) of water column.