A flexible package of fiber material with a flap and its manufacturing method

Abstract

The invention relates to a flexible package (10) made of fiber material and provided with a flap (11 b), wherein a first wall (11 ) and a second wall (12) are made of a fiber material having at least one heat-sealable surface and are arranged against each other to form the inner surface of the flexible package (10). The upper part of the first wall (11 ) constitutes the flap (11 b) of the flexible package, arranged to be heat sealed onto the upper part (12a) of the second wall, to constitute a heat-sealed joint closing the openable side of the flexible package (10). The flap (11 b), the upper part (12a) of the second wall of the package, and the heat-sealed joint are folded as a flap structure onto the outer surface of the second wall (12a), to be glued onto the outer surface of the second wall (12a) by means of an adhesive area (17) provided between the upper part (12a) of the second wall and the outer surface of the second wall (12). The invention also relates to a method for manufacturing a flexible package (10) made of fiber material and provided with a flap (11 b).

Description

[0001] A FLEXIBLE PACKAGE OF FIBER MATERIAL WITH A FLAP AND ITS MANUFACTURING METHOD

[0002] Field of the invention

[0003] The invention relates to a flexible package made of fiber material and provided with a flap, to be opened by lifting up the flap. The invention also relates to a method for manufacturing a flexible package made of fiber material and provided with a flap.

[0004] Background of the invention

[0005] In Europe, there are 87 million people with various handicaps, as well as about 100 million elderly people, and this number is rapidly increasing. Consequently, there is a need for a fiber package which is easily opened and openable and simultaneously protects goods well.

[0006] Many foods would last longer if a fiber package would better protect it from ambient conditions from the manufacture all the way to the consumer. Examples of products include flour and flakes. For cost reasons and in the absence of alternatives, food packagers are often contented with merely gluing lightly the mouth of a bag folded at its upper edge. Along with rapid development of fiber materials in recent years, heat-sealable options have entered the market. A problem with almost all present flexible packages made of fiber materials and sealed in an adhesive area by ultrasonic or heat sealing, is that they are difficult to open. Such a package is normally opened by tearing part of the package open underneath and in parallel with a heat sealed joint. Packages seldom open easily and straight, which is why many consumers use scissors or another tool to open a package. An irregularly opened package is difficult to handle, and it is also aesthetically unattractive. Some of the information provided on the package may be lost with the strip tom off.

[0007] There are also plastic packages, provided with flaps, which are opened, for example, by lifting up the flap from that wall of the package to which it has been attached upon closing the package. For paper packages, there is no way of opening a heat sealed paper package by lifting up from the front wall to which it has been attached. If the flap has been glued onto the front wall, lifting it up is likely to cause splitting, i.e. delamination of paper in the wall. Even if the glue did not tear the wall of the package, it is a poor option, because it is difficult to find an environmentally safe and recyclable adhesive which would not be permeable to gases and moisture. Food manufacturing brands reject adhesives when they want a product to be protected from gases, oxygen and grease. Instead of adhesive, they prefer heat sealing.

[0008] If adhesive is used, one option is to use a laminate or a multi-ply paper, whereby only one ply is detached with the adhesive surface, but this increases costs. Plastic packages, in turn, are an undesirable choice because of the difficulty in recycling and composting them and the tightening legislation imposing restrictions on plastic packages and their use.

[0009] Consequently, there is a high demand on the market for an environmentally safe heat-sealable package which is made of a mono-material, such as paper or other fiber, and which can be easily opened, without tools, by lifting the flap off the front wall of the package.

[0010] Brief summary of the invention

[0011] The scope of the different embodiments of the invention is defined in the independent claims. Some additional features are defined in the dependent claims. The embodiments, examples and possible features described in this specification and not falling within the scope of the independent claims shall be interpreted as examples which are useful for understanding the different embodiments of the invention.

[0012] The invention relates to a flexible package which is made of fiber material and provided with a flap, and whose first wall and second wall consist, on at least one surface, of heat-sealable fiber material and are arranged opposite each other to form the inner surface of the flexible package. The top part of the first wall constitutes the flap of the flexible package, arranged to be heat sealed to the top part of the second wall, for forming a heat sealed joint closing the openable side of the flexible package. The lower part of the flap, the top part of the second wall of the package, and the heat sealed joint are folded as a flap structure onto the outer surface of the second wall, to be glued onto the second outer surface in an adhesive area provided between the top part of the second wall and the outer surface of the second wall.

[0013] In an embodiment, the fiber material of the flexible package is heat-sealable on two sides. In an embodiment, the flap is single-ply. In an embodiment, the flap is three-ply, formed as a flap from the top part of the first wall, comprising three flap sections, by folding the middle flap section onto the lowermost flap section and by attaching the middle section by heat sealing to the lowermost section and by folding and gluing the topmost flap section and the middle flap section together. In an embodiment, the fiber material is heat-sealable on both sides, and the flap is a two-ply flap formed as a flap from the top part of the first wall comprising two flap sections, by folding the upper flap section onto the lower flap section and by attaching the upper section to the lower section by heat sealing. In an embodiment, the fiber material is paper, paperboard or laminate, the laminate comprising one or more layers of fiber material. In an embodiment, the flexible package is formed of a single fiber material blank or two material blanks. In an embodiment, the side edges of the flexible package are heat sealed up to the heat-sealed joint of the open side so that the flexible package is tightly sealed. In an embodiment, the adhesive used for attaching the flap may be heat sealing adhesive or pressure sensitive adhesive.

[0014] The invention further relates to a method for manufacturing a flexible package provided with a flap. The method comprises at least the following steps: providing at least one fiber material piece, having at least one heat- sealable surface, as a first wall of the package and as a second wall of the package so that the heat-sealable surfaces of the first and second walls are arranged against each other; making a flap for the flexible package out of the top part of the first wall; attaching the lower section of the flap and the top part of the second wall of the package to each other by heat sealing, to close the openable side of the flexible package; folding the lower section of the flap, the upper part of the second wall of the package and the heat sealed joint onto the second wall, to form a flap structure; and gluing the top part of the second wall, folded onto the outer surface of the second wall of the package, to the second wall.

[0015] In an embodiment, the top part of the second wall is glued onto the second wall in an adhesive area provided between the top part of the second wall and the outer surface of the second wall. In an embodiment, at least the first side of the first wall of the flexible package and at least the first side of the second wall of the package are attached to each other by heat sealing up to the heat sealed joint of the open side, for forming a side seam of the flexible package.

[0016] Description of the drawings

[0017] In the following, the invention will be described in more detail with reference to the appended drawings, in which

[0018] Fig. 1 a shows a perspective view of a flexible package according to the invention, made of fiber material and provided with a single-ply openable flap, when the package is still in the blank stage;

[0019] Fig. 1 b shows a perspective view of the flexible package of Fig. 1 a after the mouth of the package has been sealed;

[0020] Fig. 1 c shows a perspective view of the flexible package of Fig. 1 a after the mouth of the package has been sealed and the flap has been attached in place;

[0021] Fig. 1 d shows a flexible package, made of fiber material and provided with a single-ply openable flap, in a cross-sectional view from the side when the package is still in the blank stage, unsealed;

[0022] Fig. 1 e shows the flexible package of Fig. 1 d in a cross-sectional view from the side after the mouth of the package has been sealed;

[0023] Fig. 1f shows the flexible package of Fig. 1d in a cross-sectional view from the side after the mouth of the package has been sealed and the flap has been attached in place; Fig. 2a shows a perspective view of a flexible package according to the invention, made of fiber material and provided with a three-ply flap, when the three- ply flap and the package are still in the blank stage;

[0024] Fig. 2b shows the flexible package of Fig. 2a in a cross-sectional view from the side after the formation of a first fold in the three-ply flap of the package;

[0025] Fig. 2c shows the flexible package of Fig. 2a in a cross-sectional view from the side after the formation of a second fold in the three-ply flap of the package;

[0026] Fig. 2d shows the flexible package of Fig. 2a in a cross-sectional view from the side after the sealing of the mouth of the package;

[0027] Fig. 2e shows the flexible package of Fig. 2a in a cross-sectional view from the side after the mouth of the package has been sealed and the three-ply flap has been attached in place;

[0028] Fig. 3 represents a flow chart of a method for manufacturing a paper package according to the invention, made of fiber material and provided with a flap; and

[0029] Fig. 4 shows a perspective view of a flexible package according to the invention, made of fiber material, after the top edge of the first and second walls of the flexible package have been folded towards the inside of the flexible package for heat sealing of the folds, to make an openable flap, when the package is still in the blank stage.

[0030] Detailed description of the invention

[0031] A problem with many heat-sealable flexible packages made of fiber material and currently in use is that the package is opened by tearing in a direction parallel to the mouth, whereby a strip is left in one’s hand, and furthermore, the package may be torn at a very low location so that the contents do not remain in the package as desired. Paper bags which have glued seams and which are folded at the top do not always provide the best protection needed for food, and the shelf life of the product becomes shorter. Package manufacturers are guided by legislation, wishes of consumers, as well as environmental objectives for brands to find alternatives for plastic as a material for flexible packages, and the selection thus naturally focuses on coated natural fibers. So it is highly environmentally friendly and advantageous to recycle and reuse the fiber of flexible packages made of fiber material, because studies show that it can be recycled several times until the mechanical properties of the fibers are impaired. In the light of current research, paper can be recycled several times, up to 10 times.

[0032] Conventional flexible packages made of fiber material, such as paper packages, are closed by a single adhesive area, for example with glue, by ultrasonic sealing or by heat sealing. In this context, the term flexible package also comprises bags. The adhesive area is formed between walls of the flexible package, or between a flap and one wall. In this application, a wall refers to a wall delimiting the package, or a part of a wall, such as a front wall or a rear wall. To better preserve the products, such as food, contained in the package, and to ensure hygiene, the seam formed by the adhesive area must be impermeable and hermetic. To open the package, different walls of the package are separated from each other mechanically, for example by pulling the walls apart in a direction transverse to the seam, whereby the adhesive seam formed by a glue or other adhesive area at the top part of the bag opens by detaching from at least one surface or, alternatively, the seam is split. In the case of a flexible package with a flap, the package is opened by detaching, normally lifting up, the flap from the wall onto which it has been seamed. Some flexible packages can also be opened, for example, by tearing off a material area at the top part of the package, over the whole width of the top part of the bag, or by removing a material area at a corner of the package. However, such a way of opening produces garbage in the form of the part removed upon opening.

[0033] Thus, there is a need for an inexpensive and flexible package which is made of thin paper or other fiber material and is easily openable without breaking the package. A flexible package according to the invention, made of fiber material, such as paper, and provided with a flap, as will be presented below, is one.

[0034] The flexible package according to the invention, made of fiber material and provided with a flap, is made of a material having a grammage typically lower than 250 g / m2, lower than 180 g / m2, or lower than 125 g / m2, such as 20 to 250 g / m2, 40 to 180 g / m2, or 60 to 125 g / m2. The material used in flexible packages of fiber material is preferably recyclable, but it may also be compostable or biodegradable. The term ‘recyclable flexible paper package’ refers to flexible packages made of recyclable paper. Although paper is normally based on wood-based or other vegetable fibers, paper may also contain other fibers. Thus, raw materials for recyclable flexible paper packaging material include wood-based or cellulose-based and other vegetable fibers. Raw materials for a compostable or biodegradable flexible packaging material may also include biodegradable synthetic fibers. Many fiber materials which are being or will be developed are likely to be suitable materials as well. An example of these is a cellulose film made of regenerated, i.e. recrystallized cellulose. It is a transparent and flexible cellulose film developed to replace packaging films made of fossil plastic and to reduce environmental pollution caused by microplastics. Cellulose film is resistant to moisture but breaks down in nature just as well as paper and is bio-based and biodegradable.

[0035] A flexible package made of fiber material and provided with a flap can be formed of a single fiber material blank having at least one heat-sealable surface. In other words, a thermoplastic layer is provided on at least one surface. Thus, the front wall and the rear wall of the package are formed by folding part of the material blank so that the heat-sealable surfaces remain inside the package, i.e. are part of the inner surface of the bag. A bottom is formed by one or more folds at the lower edge of the package. The side seams of the package are preferably formed by heat sealing.

[0036] At the top part of the flexible package made of fiber material and provided with a flap, the flap is formed from the upper part of either the front wall or the rear wall, and folded - in the case of a flap formed of the front wall - partly onto the upper part of the rear wall, across the mouth, i.e. the open side, of the package, or - in the case of a flap formed of the rear wall - partly onto the upper part of the front wall, across the mouth of the package. The part on the side of the mouth of the package is called the top part of the package, the opposite part is called the lower part of the package, and the two other edges between the top part and the lower part are called the side parts, i.e. the sides. The flap may be a single-ply or three-ply flap folded from a blank. A single-ply flap may also be reinforced by providing a separate tab of material on top part of the flap. Like the walls, the tab can consist of recyclable paper, i.e. a slip of paper, or paper tape, i.e. a slip of paper tape. It may consist of the same material as the walls of the package, or of a different material. If the flap is three-ply, it is formed by folding the terminal i.e. upper end of the first wall by two folds in an accordion fold into three different sections or lengths of the material blank, as shown in the series of images shown in Figs. 2a to 2e. Thus, the three-ply flap comprises three foldable faces / flap sections and two folds. The first flap section of the flap, which may also be called the first face, constitutes the section remaining as the outer surface of the flap and determining the height of the flap; the second, middle flap section, or face, is substantially equal in height with the flap to be formed, i.e. with the first flap section, or slightly lower than it; and the third or uppermost flap section, the third face, is arranged to have such a height that it is not visible when the flap is folded onto the wall. Preferably, the middle flap section is lower or not higher than the first flap section, so that the flap can be folded more easily onto the second wall. If it were higher, then folding onto the second wall would be more difficult when three layers were to be folded instead of a single wall. The folding lines are between the faces.

[0037] The mouth of the flexible package made of fiber material and having a flap is closed by heat sealing, i.e. by making a heat-sealed joint comprising at least one heat seal stripe. Consequently, the mouth is closed by a heat-sealed joint consisting of one or more narrow heat seal stripes. In general, heat sealing provides a reliable sealing for closing the flexible package, but when the heat- sealed joint is formed of several heat seal stripes, an even tighter seam can be obtained which may also be easier to open than a single heat seal stripe having a greater thickness. The side seams can also be formed by one or more heat seal stripes. By a desired number of heat seal stripes, the package is provided with a desired retention capacity for water, greases, vapours, aromas, and / or gases.

[0038] A flexible package made of fiber material and provided with a flap can be made by a vertical packaging machine. In which case, the package is easiest to fill in from the side after the seam closing the mouth and one of the two side seams have been closed by heat sealing. After filling, the other side seam is closed as well. However, a horizontal packaging machine can also be used for manufacturing a flexible package made of fiber material and provided with a flap. Thus, the package is normally filled in from above via the mouth before the heat sealing of the mouth, but it can also be filled in from the bottom if the package is made of at least two material blanks. When filling from the bottom, both the mouth and the sides of the package are seamed by heat sealing before filling the package. In other words, as an alternative to a single material blank, the front wall and the rear wall can be formed of separate blanks by placing the heat-sealable surfaces of the two separate material blanks against each other.

[0039] A three-ply flap for the flexible package according to the invention, made of fiber material and provided with a flap, is formed of a first wall of the package. The first wall may be either the rear wall or the front wall. The first and second faces of the blank for the flap, i.e. flap sections, are heat sealed together, and the third face, or flap section, is glued onto the second face or flap section, onto the side opposite to the side where the heat-sealed joint was formed in connection with heat sealing of the first and second face. If the flap of the flexible package made of fiber material and provided with a flap is single-ply, it does not need to be formed separately but it is already formed of the upper section of the first wall. When the flap is finished, the mouth is closed by heat sealing the mouth of the package; in other words, the single or three-ply flap and the counter surface of the second wall, which is the upper part of the second wall, are heat sealed together. After the heat sealing, they are folded together with the heat-sealed joint onto the side of the second wall of the package, where the upper part of the second wall is permanently fixed by an adhesive, such as an adhesive glue. In doing so, the package is first closed by heat sealing the flap formed of the first wall of the package onto the inner surface of the upper part of the second wall, and the flap structure is then formed by folding the flap, the upper part of the second wall and the heat-sealed joint onto the side of the second wall, and by attaching the folded upper part of the second wall to the outer surface of the second wall. The package formed in this way is tight but easy to open simply by pulling or lifting up the flap towards the top edge of the package. Peeling of the package is impossible when such a structure is used, or at least it is very unlikely in practice, even if the material itself had easily peelable characteristics. In addition to a single-ply or three-ply flap, the flap can also be made two-ply in layer thickness, if the material used for the flexible package is heat-sealable on both sides. In such a case, a two-ply flap is first formed by heat sealing of two faces, i.e. flap sections, of the upper part of the first wall, by folding together and heat sealing the flap sections. The mouth of the package is closed by heat sealing according to the invention, as in the case of a single-ply or three-ply flap, but the material heat-sealable on both sides also makes it possible that the counter surface of the flap, which is the inner surface of the flap and the first wall and is folded towards the second wall of the package, can be attached by heat sealing to the outer surface of the second wall of the package. It should be noted here that a single-ply flap and a three-ply flap can also be formed of a material which is heat-sealable on one side only, which is less expensive than a material heat-sealable on both sides. Moreover, it should be noted that two-ply, three-ply, reinforced single-ply or at least partly three-ply flaps make a more rigid and stronger structure than a single-ply flap, and the package can thus be easier to open.

[0040] Advantageously, the adhesive used in the manufacture of the package must under no circumstances come into contact with the inside of the package and / or the products contained in the package. The flexible package according to the invention, made of fiber material and provided with a flap, is such a packaging concept. This is because the three-ply flap contains adhesive between the first and second faces only, neither of which are in contact with the product or the lower face of the flap (folded towards the second wall of the package), and no adhesive can run towards or to the inside of the package during the manufacture of the package, because the open side of the surfaces to be glued is not towards the inside of the package but it faces upwards, in the direction of the upper part of the package, when the flap is folded into place. Similarly, when the flap is folded onto the outside of the second wall and attached to it with adhesive, the adhesive is between the second wall and the upper part of the second wall which is folded onto the outer surface of the second wall, and this area is not in contact with the product or the inner surface of the package either, and no adhesive can run towards or to the inside of the package during the manufacture of the package, because the open side between these surfaces is not facing the inside of the package either, but downwards, towards the bottom of the package. In a single-ply flap, adhesive is only provided between the second wall and the upper part of the second wall which is folded onto the outer surface of the second wall, and it cannot enter the inside of the package for the reason mentioned above. In a two-ply flap made of a material which is heat-sealable on both sides, there is no adhesive at all, or adhesive is only provided between the second wall and the upper part of the second wall which is folded onto the outer surface of the second wall.

[0041] The adhesive surface, i.e. the adhesive area, on the package can be provided by one or more different adhesives in a uniform adhesive area or in one or more adhesive stripes. In this context, providing means applying i.e. gluing adhesive on the surface of the material. The adhesive used can be any suitable adhesive which is preferably made of any suitable glue known in the manufacture of pressure-sensitive labels, such as hot-melt, acrylic emulsions, transfer adhesives, glue, chemically reactive type glues, but it can also be formed of other suitable adhesives. The adhesive may be selected considering the requirements of recyclability and compostability. Primarily, hot-setting adhesive can be used, but liquid adhesive is feasible as well, because the adhesive areas are not in contact with the inner surface of the package, as explained above.

[0042] The invention and its examples and embodiments will be described in more detail below in connection with the figures.

[0043] Figure 1 a shows a perspective view of a flexible package 10 according to the invention, made of fiber material and provided with a single-ply flap 11 b. In Fig. 1 a, the package 10 is still unsealed in the blank stage; in other words, the side seams or the mouth 19 have not been sealed yet. The package 10 is formed of a uniform material blank comprising a first wall 11 and a second wall 12 which are folded against each other in a direction shown by an arrow 15. The surfaces of the first wall 11 and the second wall 12 coming against each other have heat-sealable characteristics. The first wall 11 is divided into two areas: an actual wall section 11 a and a flap section, i.e. a flap, 11 b, with a flap folding line 14b extending between them, along which the flap 11 b is arranged to be folded onto the second wall 12 after the heat sealing of the mouth 19. The folding line 14b is illustrated with a broken line. The upper part of the second wall 12 is indicated with reference numeral 12a, and it is that area of the wall 12 which is folded with the flap 11 b onto the second wall 12 after the sealing of the mouth 19. The folding line 14a of the second wall is illustrated with a broken line. Thus, the mouth 19 of the package is formed between the upper parts of the first wall 11 and the second wall 12. The mouth 19 is closed and sealed by heat sealing the flap 1 1 b of the first wall 11 , more precisely the lower part of the flap 11 b, onto the upper part 12a of the second wall 12. The locations for a joint to be heat sealed are indicated on the walls 11 , 12 with reference numerals 13a and 13b, respectively. After the heat sealing, when the flap 11 b and the upper part 12a of the second wall are folded onto the second wall 12 for forming the flap structure, the heat-sealed joint is folded, too. The upper part 12a of the second wall and the second wall 12 are glued together with adhesive in an adhesive area 17. At the same time, the flap 11 b remains folded onto the second wall 12, thanks to the heat sealing.

[0044] Figure 1 b shows a perspective view of the flexible package 10 of Fig. 1 a, made of fiber material and provided with a flap 11 b, after the mouth 19 of the package

[0045] 10 has been heat sealed. Thus, the heat-sealed joint is not formed between the upper part 12a of the second wall and the wall section 11 a of the first wall

[0046] 11 but between the upper part 12a of the second wall and the flap 11 b; and the heat-sealed joint is folded, at folding lines 14b and 14a, with the flap 11 b and the upper part 12a of the second wall onto the second wall 12, in the form of a flap structure which is glued onto the second wall 12 at the location of the adhesive area 17. When the flap structure is glued in place, the upper edge 18b of the first wall 11 of the package 10 and the upper edge 18a of the second wall 12 are facing down, towards the bottom, or lower part, of the package 10. The direction of folding the flap structure is indicated with an arrow 16.

[0047] Figure 1 c shows a perspective view of the flexible package 10 of Fig. 1 a, made of fiber material and provided with a flap 11 b, after the heat-sealed mouth 19 of the package 10, the flap 11 b and the upper part 12a of the second wall have been folded at the folding lines 14a, 14b onto the second wall 12, and the flap structure formed by folding has been attached to the second wall 12 by gluing.

[0048] The bottom of the package 10 shown in Figs. 1 a to 1 c has a single fold, but it could also have two or more folds. The walls 11 , 12 of the package 10 are formed by folding the material blank so that a bottom is formed at the lower edge of the package 10 either by said single fold or several folds, and so that the heat-sealable surfaces of the material blank come against each other. Alternatively, the walls 11 , 12 are formed by placing heat-sealable surfaces of two separate material blanks against each other; the bottom can also be provided as a separate blank.

[0049] Figure 1 d shows a flexible package 10a of fiber material, provided with a single-ply flap 11 b, in a cross-sectional view from the side when the package 10a is open; in other words, the mouth of the package has not been heat sealed, yet. The flexible package 10a of Fig. 1d corresponds to the flexible package 10 of Figs. 1 a to 1 c in other respects but its bottom structure is different, having two folds, so that the package 10a stands on its own.

[0050] Figure 1 e shows the flexible package 10a of Fig. 1 d in a cross-sectional view from the side after the mouth 19 of the package 10a has been sealed by a heat-sealed joint at locations 13a and 13b.

[0051] Figure 1f shows the flexible package 10a of Fig. 1 d in a cross-sectional view from the side after the mouth of the package has been sealed and the heat- sealed joint, the flap 11 b of the first wall 11 and the upper part 12a of the second wall 12 have been folded along the folding lines 14b and 14a onto the second wall 12 to form a flap structure which has been glued onto the second wall 12 at the location of the adhesive area 17.

[0052] Figure 2a shows a perspective view of a flexible package 20 according to the invention, made of fiber material and provided with a three-ply flap 21 b, when the three-ply flap 21 b and the package 20 are still in the blank stage. The package 20 is formed by folding the first wall 21 and the second wall 22 partly on top of each other. The side seams and the mouth of the package 20 are not yet sealed in Fig. 2a. At least those surfaces of the first wall 21 and the second wall 22 which come against each other after the folding, i.e. are facing the inside of the package 20, are heat sealable. The first wall 21 is divided into two sections: the actual wall section 21 a and a flap section, i.e. flap 21 b, between which a flap folding line 23a is provided, along which the flap 21 b is arranged to be folded onto the second wall 22 after the sealing of the mouth. The folding line 23a is indicated by a broken line. The upper part of the second wall 22 is indicated by reference number 22a, and this area of the wall 22 is folded with the flap 21 b and the heat-sealed joint onto the second wall 22 after the heat sealing of the mouth 19, to form the flap structure, and is glued onto the outer surface of the second wall 22. The folding line 23d of the second wall is indicated by a broken line.

[0053] A three-ply flap 21 b is formed by pleating three different flap blank sections of the terminal i.e. upper part of the first wall 21 , i.e. lengths / faces 24a, 24b, 24c in an accordion-like manner, as shown in the series of images in Figs. 2a to e. The first flap blank section 24a of the flap, which may also be called the first flap face, constitutes the section remaining as the outer surface of the flap 21 b, and thereby also part of the package 20, and determines the height of the flap 21 b; the second flap blank section 24, or the second flap face, is substantially equal in height to or slightly lower than the flap 21 b itself to be formed, or the first flap blank section 24a; and the third flap blank section 24c, or the third flap face, is formed to have such a height that it will not be visible when the flap 21 b is folded onto the second wall 22. Again, the mouth of the package 20 is formed between the upper part of the first wall section 21 a and the upper part 22a of the second wall, and remains heat-sealed underneath the flap 21 b being folded.

[0054] Figure 2b shows the flexible package 20 of Fig. 2a in a cross-sectional view from the side after the folding of the three-ply flap 21 b of the package 20 has been started and the first pleat has been made. The first pleat is made by folding the first flap blank section 24a and the second flap blank section 24b against each other, along the first folding line 23b of the flap 21 b between them, their heat-sealable surfaces coming against each other upon folding. When folding the first flap blank section 24a and the second flap blank section 24b against each other, the second flap blank section 24b is folded towards the inside of the package 20. The first flap blank section 24a and the second flap blank section 24b are heat-sealed against each other by a heat-sealing joint 28a.

[0055] Figure 2c shows the flexible package 20 of Fig. 2a in a cross-sectional view from the side after the second pleat of the three-ply flap 21 b of the package 20 has been made. The second pleat is made by folding the second flap blank section 24b and the third flap blank section 24c against each other, along the second folding line 23c between them; in this pleat, the heat sealing surfaces of the second flap blank section 24b and the third flap blank section 24c do not come against each other. When folding the second flap blank section 24b and the third flap blank section 24c against each other, the third flap blank section 24c is folded towards the upper edge of the package 20; and the outer edge of the third flap blank section 24c, which is simultaneously the edge of the first wall 21 , points away from the lower part of the package 20 after the folding. The second flap blank section 24b and the third flap blank section 24c are glued against each other in the adhesive area 28b which consists of, e.g., hot- setting adhesive, liquid adhesive, or any other glue / adhesive suitable for the purpose, and comprises one or more adhesive stripes.

[0056] Figure 2d shows the flexible package 20 of Fig. 2a in a cross-sectional view from the side after the mouth of the package 20 has been closed by heat sealing. The mouth is closed and sealed by a heat-sealed joint 28c which is formed between the flap 21 b of the first wall 21 and the third flap blank section 24c, more precisely the lower part / edge of the third flap blank section 24c, and the upper part 22a of the second wall 22.

[0057] Figure 2e shows the flexible package 20 of Fig. 2a after the mouth and thereby also the package 20 have been closed by a heat-sealed joint 28c, the three- ply flap 21 b has been formed and folded together with the upper part 22a of the second wall along the folding line 23a of the flap of the first wall 21 and along the folding line 23d of the upper part 22a of the second wall, towards and against the outer surface of the second wall 22. When the flap 21 b and the upper part 22a of the second wall have been folded, after the heat sealing, onto the second wall 22 for forming the flap structure, the heat-sealed joint 28c is folded along with them. The upper part 22a of the second wall and the second wall 22 are glued to each other by the adhesive area 28d which consists of e.g. hot-setting adhesive, liquid adhesive or any other glue / adhesive suitable for the purpose, and comprises one or more adhesive stripes. At the same time, the flap 21 b remains on top part of the second wall 22, thanks to the heat- sealed joint 28c. The flexible package according to the invention is a package made of fiber material and provided with a flap, for example a paper package in which a fiber rip stopper is formed by a so-called wall fold, i.e. the upper part of the second wall foldable under the flap after the heat sealing, and in the case of a three- ply flap also the folding line / s of the plies. The fiber rip stopper stops any fiber rip, possibly caused by opening the package, at least to the wall fold, but in the case of a three-ply flap possibly also to the folding lines of the flap plies. The package is opened without the fiber rip extending down the wall of the package, so that the package is neatly opened at the desired location only. The package according to the invention cannot be tom down the wall of the package, since the fiber rip is stopped by the fiber rip stopper.

[0058] The flexible package according to the invention, comprising a flap, can be made by a method comprising at least the following steps:

[0059] - providing at least two pieces of fiber material having one heat-sealable surface, for example a first piece of paper forming a first wall of the package, and a second piece of paper forming a second wall of the package;

[0060] - arranging the heat-sealable surfaces of the first and second walls against each other; wherein the piece of paper may also be a single uniform piece of paper which is folded by placing two heat-sealable surfaces against each other to form two walls: the first wall and the second wall;

[0061] - forming a flap from the upper part of the first wall, i.e. the flap part of the first wall;

[0062] - attaching the flap and the upper part of the second wall to each other by heat sealing to form a heat-sealing joint, a seam, closing the mouth i.e. the open side of the package;

[0063] - folding the flap and the upper part of the second wall, comprising the heat-sealing joint, downwards to the side of the second wall of the package;

[0064] - attaching the upper part of the second wall to the second wall of the package by an adhesive area;

[0065] - attaching at least the first side of the package by an adhesive, such as a glue, by ultrasonic sealing or by heat sealing, to form a side seam of the package. At some point in the manufacturing process, both side edges, i.e. side areas, of the flexible package are heat sealed up to the heat-sealed joint of the open side, to close the flexible package tightly. In the above mentioned method, any fiber material suitable for the purpose can be applied in the flexible package. The flexible package according to the invention, made of recyclable material and provided with a flap, can be made by using machines, equipment and methods typically used in the industry.

[0066] Figure 3 shows a method 30 for manufacturing a flexible package according to the invention, made of fiber material and provided with a flap, in a flow chart. The method 30 comprises at least the following steps, whose sequence may vary. In a method step 31 , a piece of fiber material, such as a piece or pieces of recyclable paper is / are arranged as a first wall and a second wall of a package, the walls having at least one surface of heat-sealable material. The heat- sealable surfaces of the material are arranged as the inner surfaces of the package, facing each other. In a method step 32, a flap for the flexible package is formed of the upper part of the first wall. In a method step 33, the lower section of the flap of the package and the upper part of the second wall of the package are attached to each other by heat sealing to close the openable side, i.e. the mouth, of the package. Heat sealing provides a heat-sealed joint between the lower section of the flap and the upper part of the second wall of the package. In a method step 34, the lower section of the flap, the upper part of the second wall of the package, and the heat-sealed joint are folded onto the second wall, to constitute the flap structure. In a method step 35, the upper part of the second wall, folded onto the outer surface of the second wall of the package, is glued to the second wall with an adhesive, to glue the flap structure onto the second wall.

[0067] Fig. 4 shows an alternative flexible package 40 according to the invention. Here, the top edge 48b of the first wall 41 of the flexible package 40 and the top edge 48a of the second wall 42 have been folded towards the inside of the flexible package 40 and heat sealed 45 against the walls 41 , 42. For illustration, the folds are still partly apart from the walls 41 , 42, to which they are sealed by heat-sealed joints 45. Thus, the folds become part of the flap structure. These heat-sealed joints 45 connect the inner surfaces of the flexible package 40 below the folding lines 45a and 45b, i.e. on the side of the bottom of the flexible package 40. The mouth 49 of the flexible package 40 is closed by heat sealing the first wall 41 to the second wall 42 at the location indicated by the points 43a and 43b. The flap structure is then folded onto the second wall 42 at the location indicated by the points 44a and 44b. The flap structure is glued onto the second wall 42 at the location of the adhesive area 47. The adhesive can be applied on merely one of the counter surfaces, as shown in the figure, or both. If the flexible package 40 is closed before the flexible package 40 is filled with the product, the flexible package 40 can be filled from the edge or from the bottom. In view of the manufacturing technique, it may be easier to first finish the flap structure and then fill in the flexible package 40 with the product. When the edges of the flexible package 40 are seamed after the gluing of the flap structure, the folded upper edge areas are naturally not seamed, if the outer surfaces of the walls 41 and 42 of the flexible packaging material are not heat-sealable. Thus, they do not begin to tear off when the flap is pulled open. This kind of a flap structure is also thicker, so the person opening it can handle it more briskly. In addition to these advantages, the lower surface of the flap structure in this concept with the folded upper edge provides a larger printable surface which can be printed with any information that will be revealed to the consumer first after opening the package. A pleat is formed at the bottom of the flexible package 40 by folding or by using a separate strip of material. The series of images showing the implementation of the flap structure is, in principle, similar to the series of Figures 1 and 2.

[0068] It should be noted that in some cases, the heat-sealed joint folded with the flap and with the upper part of the second wall, to be glued onto the second wall, can be replaced with adhesive tape provided either in the lower part of the flap in the first wall, or in the upper part of the second wall of the package, for closing the mouth.

[0069] The features of the invention described and the embodiments mentioned in the application are freely combinable and interchangeable, except if the application particularly states that the embodiments or features are not interchangeable. The exemplary features described in connection with the different embodiments can be used with any other embodiment even if this were not mentioned separately.

Claims

Claims:

1. A flexible package (10), made of fiber material and provided with a flap (11 b), whose first wall (11 ) and second wall (12) consist, on at least one surface, of heat-sealable fiber material and are arranged opposite each other to form the inner surface of the flexible package (10), wherein the upper part of the first wall (11 ) constitutes the flap (11 b) of the flexible package, arranged to be heat sealed to the upper part (12a) of the second wall (12) for forming a heat-sealed joint closing the openable side of the flexible package (10), characterized in that the flap (11 b), the top part (12a) of the second wall of the flexible package (10), and the heat-sealed joint are arranged to be folded as a flap structure onto the outer surface of the second wall (12), and to be glued onto the outer surface of the second wall (12) by means of an adhesive area (17) provided between the top part (12a) of the second wall and the outer surface of the second wall (12), and wherein the heat-sealed joint of the flexible package (10) is arranged to be opened by lifting up the flap (11 b) of the flap structure.

2. The flexible package (10) according to claim 1 , characterized in that the fiber material of the flexible package (10) is heat-sealable on both surfaces.

3. The flexible package (10) according to claim 1 or 2, wherein the flap (11 b) is single-ply.

4. The flexible package (10) according to claim 1 or 2, wherein the flap (11 b) is three-ply, formed as the flap (11 b) from the top part of the first wall (11 ), comprising three flap sections, by folding the middle flap section onto the lowermost flap section and by attaching the middle section to the lowermost section by heat sealing, and by folding and gluing the uppermost flap section and the middle flap section together.

5. The flexible package (10) according to claim 1 or 2, wherein the fiber material is heat-sealable on both sides, and the flap is a two-ply flap (11 b) formed as the flap (11 b) from the top part of the first wall (11 ), comprising two flap sections, by folding the upper flap section onto the lower flap section and by attaching the upper section to the lower section by heat sealing.

6. The flexible package (10) according to any of the claims 1 to 5, wherein the fiber material is paper, cardboard or laminate, the laminate comprising one or more fiber material layers.

7. The flexible package (10) according to any of the claims 1 to 6, which is formed of one fiber material blank or two fiber material blanks.

8. The flexible package (10) according to any of the claims 1 to 7, wherein the side edges of the flexible package (10) are heat sealed up to the heat-sealed joint of the open side so that the flexible package (10) is tightly sealed.

9. The flexible package (10) according to any of the claims 1 to 8, characterized in that the adhesive may be hot-setting adhesive or pressure sensitive adhesive.

10. A method for manufacturing a flexible package (10) made of fiber material and provided with a flap (11 b), wherein the flexible package (10) is arranged to be opened by opening the heat-sealed joint closing the flexible package by lifting up the flap (11 b), and the method comprising at least the following steps: providing at least one piece of fiber material having one heat-sealable surface, as a first wall (11 ) and a second wall (12) of the package so that the heat- sealable surfaces of the first and second walls (11 , 12) are arranged against each other; making a flap (11 b) for the flexible package out of the upper part of the first wall (11 ); attaching the lower section of the flap (11 b) and the upper part (12a) of the second wall of the package to each other by heat sealing, to close the openable side of the flexible package (10); folding the flap (11 b), the upper part (12a) of the second wall of the package and the heat sealed joint onto the second wall (12), to form a flap structure; andgluing the upper part (12a) of the second wall, folded onto the outer surface of the second wall (12) of the package (10), to the second wall (12).

11. The method according to claim 10 for manufacturing a flexible package(10) made of fiber material and provided with a flap (11 b), wherein the upper part (12a) of the second wall is glued onto the second wall (12) by means of an adhesive area provided between the upper part (12a) of the second wall and the outer surface of the second wall (12).

12. The method according to claim 10 or 11 for manufacturing a flexible package (10) made of fiber material and provided with a flap (11 b), comprising attaching at least the first side of the first wall and at least the first side of the second wall (12) of the flexible package (10) to each other by heat sealing up to the heat-sealed joint of the open side, to form a side seam of the flexible package (10).

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