EP1595816A1

EP1595816A1 - Easily openable packaging bag

Info

Publication number: EP1595816A1
Application number: EP03756647A
Authority: EP
Inventors: Tatsumi K. K. Hosokawa Yoko MORIYOSHI; Tadayuki K. K. Hosokawa Yoko KOYANAGI; Tooru K. K. Hosokawa Yoko SASAKI; Tomonari K. K. Hosokawa Yoko SHINOHARA; Tetsuo Asahi Kasei Pax Corporation MATSUSHITA
Original assignee: Hosokawa Yoko KK
Current assignee: Hosokawa Yoko KK
Priority date: 2002-10-16
Filing date: 2003-10-16
Publication date: 2005-11-16
Also published as: EP1595816A4; WO2004035415A1; AU2003301418A1

Abstract

An easily openable packaging bag has a bag body, is provided with a tear tape, and is capable of exercising satisfactory sealing performance, of being subjected to a heating process, such as boiling, and of being opened by pulling the tear tape by a low force to tear off an annular part of the bag body and to take out the contents. The easily openable packaging bag has a tubular bag body formed by folding a plastic film (3), fusion-bonding superposed opposite side edge parts of the plastic film in a fin seal (1) consisting of an over layer (3-1) and an under layer (3-2), and fusion-bonding the opposite open ends of the tubular bag body. A tear tape (2) is inserted between the over and the under layer of the fin seal (1) and fusion-bonded at least at a position on the fin seal (1) together with the opposite side edge parts of the plastic film (3) forming the over and the under layer of the fin seal (1) so that an outer end part thereof extends outside. Tear initiating parts (5) are formed in parts of the outer edge of the fin seal (1) on the outside of the side edges of the tear tape (2). An easily breakable part (6) is formed in a part, continuous with the under layer (3-2) of the fin seal (1), of the tubular bag body, on a longitudinal extension of the tear tape (2) and a part, extending from the inner edge of the fin seal (1), of the tubular bag body.

Description

TECHNICAL FIELD

The present invention relates to a pillow type easily openable packaging bag provided with an unsealing tape, capable of being subjected to a heating process, such as a boiling process, of being cut along a circular cutting line for unsealing and of exercising sealing performance, and to a easily openable packaging bag having a packaging body formed from a plastic film and capable of being unsealed by cutting its circumference along a circular cutting line to facilitate taking out the contents.

BACKGROUND ART

Background art related with a first aspect of the present invention will be explained.
Generally, a bag formed from a plastic film is unsealed to take out the contents of the bag. Some bag is unsealed by cutting the bag with a pair of scissors, a kitchen knife or a knife. Some bag that can be unsealed without using such a tool is provided with a tearing part, such as a tear notch, a small cut or an area having a roughened surface, formed near a sealed end or a bent part of the bag to tear the bag from the tearing part. Some bag capable of being easily unsealed has a sealed part formed by weakly bonding together parts of opposite walls and can be unsealed by pulling the opposite walls apart from each other.
A known bag disclosed, for example, in Patent document 1 having three or four sealed sides and capable of being unsealed by tearing the bag has a sealed end part having a knurled surface. A known pillow type bag disclosed, for example, in Patent document 2 formed by folding a film in two has a folded part having a knurled surface. Either of those known bags is unsealed by simultaneously tearing the opposite walls thereof in the same direction.
The bag can be unsealed and the contents of the bag can be taken out without troubles by tearing along a tearing line if the contents of the bag are not in parts corresponding to the tearing line. When a bag contains a piece of yokan, namely, a bar of bean paste, a piece of tofu, namely, a bean-curd cake, or jelly in a tight package or when a bag contains an elongate object such as a hot dog or a medical instrument, such as a syringe, so that the elongate object extends along its entire length, a part of the contents lies on the tearing line and obstructs tearing the bag. If the bag is torn by force, it is possible that the contents deform or deteriorate.
A pillow type bag having a fin seal formed by bonding opposite side edge parts of a film together and bent down so as to extend along the surface of the bag, and holding the contents in a tight package or a full package is unsealed by a method illustrated in Fig. 9. As shown in Fig. 9, the method pulls outer one of edge parts of a film bonded together to form the fin seal in a direction perpendicular to the fin seal to tear the bag into three pieces, i.e., a strip 12 and two bag bodies 11-1 and 11-2. To divide the bag into those three pieces as shown in Fig. 9 by tearing off an annular part of the bag, it is a first technically important point that a part of the outer edge part of the fin seal can be separated from the inner edge part of the film of the same at the inner edge of the fin seal and it is a second technically important point that an annular part, extending perpendicularly to the fin seal, of the bag and continuous with the part of the outer edge part of the fin seal can be torn in the strip 12.
A bag disclosed in Patent document 3 that can be unsealed by a method of unsealing a bag meeting the first technically important point separates a part of the outer edge part of a fin seal from the inner edge part of the same at the inner edge of the fin seal and tears off only the part of the outer edge part of the fin seal. Referring to Figs. 1 and 2A, the bag that can be unsealed by this method has a fin seal 1 formed by bonding together respective edge parts of an over layer 3-1 of the film and an under layer 3-2 of the film and having an outer edge 1-1 and an inner edge 1-2, and a tear tape 2 sandwiched between the over layer 3-1 and the under layer 3-2 and having a pull part extending outside from the outer edge 1-1 of the fin seal 1. Tear notches 4-1 and 4-2 are formed in the outer edge 1-1 of the fin seal 1 at positions outside the opposite edges of the tear tape 2. Another bag disclosed in Patent document 4 similar in construction to the bag mentioned above is provided with small cuts 5 formed in the outer edge 1-1 of a fin seal 1 along the entire length of the fin seal 1 at intervals as shown in Fig. 2B.
The bag is formed so that only the over layer 3-1 is torn. The tear tape 2 is bonded to the under layer 3-2 in a low bond strength so as to be easily separated from the under layer 3-2. When the tear tape 2 is pulled in the direction of the arrow a as shown in Fig. 3, the tear tape 2 is separated from the under layer 3-2. In the bag shown in Fig. 2A, a part of the outer layer 3-1 having a width corresponding to the distance between the notches 4-1 and 4-2 is torn off in a strip along tear lines extending in the directions of the arrows b-1 and b-2. In the bag shown in Fig. 2B, a part of the over layer 3-1 having a width corresponding to the distance between the small cuts 5 on the opposite sides of the tear tape 2 is torn off in a strip along tear lines as shown in Fig. 4.
Since the tear tape 2 is bonded to the under layer 3-2 in a low bond strength so that the tear tape 2 can be easily separated from the under layer 3-2, a problem arises in some cases, in the sealing performance of the joint of the tear tape 2 and the under layer 3-2. Such a method of bonding the tear tape 2 and the under layer 3-2 resulting in unsatisfactory sealing performance is unsuitable for a bag of the present invention expected to be subjected to boiling.
A bag proposed in Patent documents 5 and 6 has a fin seal 1 formed by bonding together respective edge parts of an over layer 3-1 and an under layer 3-2 of a film so as to be able to be separated at the inner edge 1-2 of the fin seal 1. In this known bag, tear notches 7-1 and 7-2 are formed in the outer edge 1-1 of the fin seal 1 As shown in Fig. 5, the under layer 3-2 has an easily breakable part 6 between tear lines extending perpendicularly to the fin seal 1 from the tear notches 7-1 and 7-2.
To unseal this bag, a tear part of the fin seal 1 between the tear notches 7-1 and 7-2 is pulled in the direction of the arrow c as show in Fig. 7. Then, the tear part of the fin seal 1 is torn along tearing lines d-1 and d-2 shown in Fig. 8, the easily breakable part 6 of the under layer 3-2 is broken when the tear part is pulled further beyond the inner edge 1-2 of the fin seal 1, and then an annular part of the over layer 3-1 demarcated by the tearing lines d-1 and d-2 is torn off.
Since the edge parts, forming the fin seal 1, of the over layer 3-1 and the under layer 3-2 are bonded together in a normal bond strength, the bag does not have any problem in sealing performance. However, the tear notches 7-1 and 7-2 formed in the outer edge 1-1 of the fin seal 1 are difficult to find. To avoid adversely affecting the sealing performance of the bag, the tear notches 7-1 and 7-2 are formed in a small depth and, consequently, the tear part between the notches 7-1 and 7-2 is difficult to hold between fingertips. The bag has a disadvantage that makes the bag to be torn unintentionally due to the accidental engagement of the tear notches with other things during handling.
A bag proposed in Patent document 7 has a fin seal provided with a U-shaped cut in its inner part and an easily tearable part in a part, including the U-shaped cut, of the fin seal. This bag also has a disadvantage similar to that of the bag mentioned above. Those easily tearable means, such as the tear notches, are difficult to find and the tear parts between the tear notches are difficult to hold between fingertips.
A bag disclosed in Patent document 8 that can be unsealed by a method of unsealing a bag meeting the second technically important point can be unsealed by tearing off an annular part of an over layer 3-1 of a film as shown in Fig. 9. To tear the annular part of the over layer 3-1, a tear tape of a narrow width is wound round the bag. A pull part of the tear tape is pulled to tear off an annular part of the bag to unseal the bag.
Although the bag does not need to be formed from a special film, a special device is needed to wind the tear tape round the bag and bond the tear tape to the film forming the bag. The special device and the tear tape increase the cost of the bag. Necessity for separating the over and the under layer of the film at the inner edge of the bonded part causes a problem in sealing performance and hence the bag is unsatisfactory for use requiring reliable sealing performance.
A tearing method not using any tear tape proposed in Patent documents 5 and 6 tears a bag formed from a linearly tearable film to tear off an annular part of the bag. Although this tearing method is applicable only to unsealing bags formed from a linearly tearable film, initial tears can be made at any parts of the fin seal of the bag to tear off an annular part of the bag.
Background art related with a second aspect of the present invention will be explained.
Sticks of chewing gum are packed in a box-shaped plastic film package formed of a plastic film for marketing. The package has a body, and a butted part having an edge provided with two notches and bent down on the body.
To take out a stick of chewing gum from the box-shaped plastic film package, the butted part is raised up from the body, a part, between the two notches, of the butted part is pulled to make initial tears in the butted part so that a pull tab is formed. The pull tab is pulled to tear off an annular part, having a width equal to that of the pull tab, of the body of box-shaped plastic film package to unseal the box-shaped plastic film package.
To tear off the annular part of the body of the box-shaped plastic film package, namely, a chewing gum package, along straight tear lines, a plastic film including a uniaxially oriented plastic film, namely, a directional plastic film, is used for forming the box-shaped plastic film package.
The box-shaped plastic film package formed from a laminated plastic film including a uniaxially oriented plastic film is more expensive than a box-shaped plastic film package formed from a laminated film including a biaxially oriented plastic film, which is an obstacle to the reduction of the cost the product.
A box-shaped plastic film package proposed in Patent document 9 has a body holding contents, opposite sealed ends, a sealed, butted part having a sealed edge provided with two notches and bent down on the body, and a tear tape circumferentially extended on the inner surface of the body from a middle part of the sealed, butted part to a part inside the sealed, butted part.
An annular part of this box-shaped plastic film package provided with the tear tape can be torn off along linear tear lines corresponding to the edges of the tear tape. Therefore, the box-shaped plastic film package can be formed from a laminated plastic film including a biaxially oriented plastic film, which is effective in reducing the cost of the product. However, since the tear tape lies in the sealed, butted part, a step is formed in the sealed, butted part and the step is an obstacle to the stable fusion-bonding of the sealed, butted part, and considerably large force need to be exerted on a part of the body continuous with the sealed, butted part to tear the same part of the body. Therefore, possible plastic films suitable for forming the box-shaped plastic film package are limited to easily tearable plastic films.
Patent document 1: JP 6-8966 A
Patent document 2: JP 63-147451 A
Patent document 3: JP 63-67273 A
Patent document 4: JP 63-67272 A
Patent document 5: JP 11-49185 A
Patent document 6: JP 2001-55248 A
Patent document 7: JP 2001-58649 A
Patent document 8: JP 2000-142726 A
Patent document 9: JP 8-91430 A

DISCLOSURE OF THE INVENTION

A first object of the present invention is to provide a pillow type easily openable packaging bag provided with a tear tape, suitable for holding contents in a tight package, and capable of exercising excellent sealing performance, of being subjected to a heating process, such as boiling, and of being circumferential torn for opening.
A second object of the present invention is to provide an easily openable packaging bag having a box-shaped case formed by folding a plastic film and capable of being circumferentially torn for opening to take out the contents.
An easily openable packaging bag in a first aspect of the present invention includes: a tubular bag body formed by folding a plastic film, fusion-bonding superposed opposite side edge parts of the plastic film in a fin seal consisting of an over layer and an under layer, and welding the opposite open ends of the tubular bag body; and a tear tape inserted between the over and the under layer of the fin seal and fusion-bonded at least a position on the fin seal together with the opposite side edge parts of the plastic film forming the over and the under layer of the fin seal so that an outer end part thereof extends outside; wherein tear initiating parts are formed in parts of the outer edge of the fin seal near and on the outside of the side edges of the tear tape, and an easily breakable part is formed in a part, continuous with the under layer of the fin seal, of the tubular bag body, on a longitudinal extension of the tear tape and a part, extending from the inner edge of the fin seal, of the tubular bag body.
The easily openable packaging bag according to the present invention may be a gusseted bag provided with gussets in opposite ends thereof.
In the easily openable packaging bag according to the present invention, an inner end part of the tear tape is held in the fin seal such that the end edge thereof is at a distance in the range of 2 to 8 mm into the fin seal from the inner edge of the fin seal.
In the easily openable packaging bag according to the present invention, the plastic film is formed by laminating a base film, an intermediate film and a fusible film in that order.
In the easily openable packaging bag according to the present invention, the intermediate film is tearable such that tears propagate in a tear propagation direction perpendicular to a direction in which the fin seal extends.
In the easily openable packaging bag according to the present invention, the base film and the intermediate film are processed by an easily breakable part forming process to form minute fissure penetrating the base film and the intermediate film laminated to the base film.
In the easily openable packaging bag according to the present invention, the plastic film is formed by laminating a base film, a barrier film, an intermediate film and a fusible film in that order.
In the easily openable packaging bag according to the present invention, the barrier film is an aluminum foil.
In the easily openable packaging bag according to the present invention, the base film, the barrier film and the intermediate film are processed by an easily breakable part forming process after lamination to form minute apertures penetrating the base film, the barrier film and the intermediate film.
In the easily openable packaging bag according to the present invention, the easily breakable part forming process presses a tool capable of forming minute fissures against the films.
In the easily openable packaging bag according to the present invention, the minute fissures are formed by pressing abrasive grains against the films.
In the easily openable packaging bag according to the present invention, the minute fissures are minute cuts formed by pressing a cutting tool against the films, and extending parallel to the inner edge of the fin seal.
In the easily openable packaging bag according to the present invention, only parts, having a width equal to 1.5 to 4 times the width of the tear tape, of the films on an extension of the tear tape are processed by the easily breakable part forming process.
In the easily openable packaging bag according to the present invention, the easily breakable part forming process forms the easily breakable part at least in a part between the fin seal and an unbonded part at a distance in the range of 1 to 10 mm from the inner edge of the fin seal.
In the easily openable packaging bag according to the present invention, the easily tearable part forming process forms many, minute, elongate, fissures extending substantially perpendicularly to the outer edge of the fin seal in a successive arrangement along the length of the fin seal.
In the easily openable packaging bag according to the present invention, a part, corresponding to the tear tape, of the fin seal is fusion-bonded over the entire width thereof
In the easily openable packaging bag according to the present invention, the base film is a single-sided sealable film, and the fin seal is fusion-bonded to the tubular bag body by partial coating.
A easily openable packaging bag in a second aspect of the present invention includes: a box-shaped case having a case body formed by folding a plastic film, fusion-bonding superposed opposite side edge parts of the plastic film in a fin seal consisting of an over layer and an under layer, forming two notches in the fin seal, sealing opposite ends of the case body in opposite sealed ends, and bending down the fin seal and the opposite open ends on the case body; and a tear tape circumferentially extended on the inner surface of a tear-off part forming part, demarcated by parallel imaginary lines extending from the two notches between a position near the inner edge the over layer of the fin seal and a position near the inner edge of under layer of the fin seal, of the case body of the box-shaped case; wherein an easily breakable part is formed so as to extend across the tear part forming part between the under layer of the fin seal and an unbonded part of the case body of the box-shaped case.
In the easily openable packaging bag according to the present invention, the easily breakable part is perforations.
In the easily openable packaging bag according to the present invention, the easily breakable part has a narrow width and a roughened surface.
In the easily openable packaging bag according to the present invention, the tear tape has a width smaller than that of the tear-off part forming part.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a sectional view of a sealed part of a prior art bag provided with a easily separable tear tape;
Figs. 2A and 2B are plan views of a prior art bag provided with a easily separable tear tape for tearing an outer layer of a fin seal provided with notches in a strip and a prior art bag provided with an easily separable tear tape for tearing an outer layer of a fin seal provided with cuts, respectively;
Fig. 3 is a sectional view of assistance in explaining the start of opening a prior art bag provided with an easily separable tear tape;
Fig. 4 is a plan view of assistance in explaining the start of opening a prior art bag provided with an easily separable tear tape;
Fig. 5 is a sectional view of a part, around tear initiating notches, of a prior art bag not provided with any tear tape;
Fig. 6 is a plan view of a part, around tear initiating notches, of a prior art bag not provided with any tear tape;
Fig. 7 is a sectional view of assistance in explaining the start of opening a prior art bag not provided with any tear tape;
Fig. 8 is a plan view of assistance in explaining the start of opening a prior art bag not provided with any tear tape;
Fig. 9 is a perspective view of either of a prior art bag and a bag of the present invention in an opened state;
Fig. 10 is a sectional view of a plastic film from which an easily openable packaging bag of the present invention is formed;
Fig. 11 is a sectional view of a part, provided with a tear tape, of an easily openable packaging bag of the present invention;
Fig. 12 is a plan view f a part, provided with a tear tape, of an easily openable packaging bag of the present invention;
Figs. 13A and 13B are sectional views of the easily openable packaging bag of the present invention at a first stage after the start of opening the bag and at a second stage after the start of opening the bag, respectively;
Fig. 14 is a plan view of the easily openable packaging bag shown in Figs. 13A and 13B;
Fig. 15 is a perspective view of an easily openable bag of the present invention; and
Fig. 16 is an enlarged sectional view of an easily openable packaging bag of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

An easily openable packaging bag in a first embodiment according to the present invention will be described with reference to Figs. 9 to 14.
An easily openable packaging bag (hereinafter referred to simply as "packaging bag") according to the present invention is formed by folding a plastid film in a tubular bag body, fusion-bonding superposed, opposite side edge parts of the plastic film in a longitudinal fin seal, and sealing the opposite ends of the bag body in lateral fin seals, respectively. One of the opposite end parts of a tear tape is sandwiched between the superposed side edge parts of the plastic film and bonded to the longitudinal fin seal by fusion-bonding with the other end part thereof extending outside from the outer edge of the longitudinal fin seal.
The packaging bag will be described with reference to the drawings.
Referring to Fig. 10 showing a plastic film 3 in a sectional view, the plastic film is a laminated film formed by laminating a base film 8, an intermediate film 9 and a fusible film 10 in that order. Suitable films as the base film 8 are drawn films of polyolefin resins, such as polypropylene resins, polyamide resins, such as nylon 6, nylon 66 and nylon 12, and polyester resins, such as polyethylene terephthalate resins.
The intermediate film 9 is a linearly tearable film for providing the plastic film 3 with a linearly tearable property. Suitable films as the intermediate film 9 are uniaxially oriented films of polyethylene resins, uniaxially oriented films of polyolefin resins, such as polypropylene resins, a biaxially oriented film having layer separation construction, drawn under a special drawing condition and formed of a polyamide resin prepared by mixing nylon 6 and a polymethaxylylene adipamide resin, and biaxially oriented film having layer separation construction, drawn under a special drawing condition and formed of a mixture of a polyethylene terephthalate resin and a polybutylene terephthalate resin. Another plastic film having a linearly tearable property and not including an intermediate film may be formed by laminating two base films such that the respective molecular orientations of the two films intersect each other.
Suitable films as the fusible film 10 are films of low density polyethylene resins, straight-chain low density polyethylene resins, copolymers of ethylene and polymerizable vinyl compounds and polypropylene resins.
When a barrier property to resist water vapor transmission, to resist oxygen transmission or to resist aroma transmission is needed, a film coated with a barrier resin layer containing, as a principal component, a polyvinylidene chloride resin or an ethylene-vinyl alcohol resin, or a film coated with a barrier metal layer of a metal oxide or a metal formed by vapor deposition is used as the base film 8 or a metal foil, such as an aluminum foil, a polyvinylidene chloride film, an ethylene-vinyl alcohol resin film, a coextruded film of those resins is sandwiched between the base film 8 and the intermediate film 9 or between the intermediate film 9 and the fusible film 10. Preferably the barrier film is sandwiched between the base film 8 and the intermediate film 9 in view of easiness in tearing the bag.
There are not any particular restrictions on the method of manufacturing the plastic film 3. Possible methods of manufacturing the plastic film 3 are a dry lamination method that laminates films by bonding together the films with adhesives, a wet lamination method, a sandwich lamination method that extrudes a molten polyethylene resin through a T-die and a thermal lamination method that laminates films of fusible resins each having a low melting point.
Fig. 11 is a sectional view of a part, provided with a tear tape, of an easily openable packaging bag of the present invention. Fig. 12 is a plan view f the part shown in Fig. 11. As shown in Fig. 11, a tear tape 2 is held between side edge parts of an over layer 3-1 and an under layer 3-2 of a film forming a fin seal 1. Easily tearable parts 5 are formed in the outer edge 1-1 of the fin seal 1 by an easily tearable part forming process. One of opposite end parts of the tear tape 2 extends outside from the outer edge 1-1 of the fin seal 1 and the other end part is sandwiched between the side edge parts of the over layer 3-1 and the under layer 3-2 such that the end edge thereof is at a distance from the inner edge 1-2 of the fin seal 1. The tear tape 2 and the side edge parts of the over layer 3-1 and the under layer 3-2 are fusion-bonded completely.
When the tear tape 2 and the side edge parts of the over layer 3-1 and the under layer 3-2 are completely bonded, the tear tape 2 and the side edge parts of the over layer 3-1 and the under layer 3-2 are fusion-bonded so that any gap may not be formed at all in the outer edge 10-1 of the fin seal 1. If the outer edge 1-1 of the fin seal 1 is not formed by complete fusion-bonding and gaps are formed in the outer edge 1-1, the tear tape 2 is unable to exert shearing force effectively on the easily tearable parts 5 when the tear tape 2 is pulled and it is difficult to initiate tears.
An easily breakable part 6 is formed by an easily breakable part forming process in the under layer 3-2 of the fin seal 1 bent down on the surface of the bag body. The easily breakable part 6 is formed in a not bonded part, on the inside of the inner edge 1-2 of the fin seal 1, of the under layer 3-2 of the fin seal 1 bent down on the bag body. Preferably, the under layer 3-2 of the fin seal 1 bent down on the bag body is fusion-bonded to the bag body to fix the bend in the fin seal 1 lightly to the bag body. When the under layer 3-2 is thus bonded to the bag body, shearing force can be effectively exerted on the easily tearable parts 5 by pulling the tear tape 2, and water can be easily removed from the packaging bag after the packaging bag has been boiled in water by a boiling process because water is unable to stay between the fin seal 1 and the bag body. A film having a heat-sealable surface layer is used as the base film 8 of the plastic film 3, and the respective heat-sealable layers of the under layer 3-2 of the fin seal 1 and the bag body are bonded together by fusion-bonding in a process of fabricating the packaging bag.
The packaging bag having the fin seal 1 may be either of a flat pillow type bag having opposite folded ends and a gusseted bag provided with gussets in opposite ends thereof. Preferably, the packaging bag is a gusseted bag when the packaging bag is intended to be filled with a jelly, a semisolid thing, such as a bar of bean paste, or a solid article because a gusseted bag can be formed in a rectangular solid. A packaging bag having the shape of a rectangular solid is capable of efficiently containing the contents and looks attractive.
The tear tape 2 is held between the side edge parts of the over layer 3-1 and the under layer 3-2 of the fin seal 1 and is fusion-bonded completely to the fin seal 1. Therefore, both the surfaces of the tear tape 2 must be capable of being bonded to the fusible film 10 of the plastic film 3 by fusion-bonding. Although the tear tape 2 may be formed from a single-layer film, it is preferable to form the tear tape 2 from a laminated film having two or more layers and resistant to tensile force. Normally, the packaging bag is provided with the single tear tape 2 in a proper part thereof. The packaging bag may be provided with two or more tear tapes.
Laminated films suitable for forming the tear tape 2 are stretched films of polypropylene resins, nylons and polyester resins each having opposite surfaces coated with resin layers, capable of being fusion-bonded to the fusible film 10, of the same resin as that forming the fusible film 10. The stretched film may be printed to facilitate finding the tear tape 2 to unseal the packaging bag. The tear tape 2 may be formed in any width provided that the tear tape 2 can be easily held between fingertips. Generally, the width of the tear tape 2 is in the range of about 3 to about 10 mm.
The length of the tear tape 2 is dependent on the length of the outer part extending outside from the outer edge 1-1 of the fin seal 1, the width of the fin seal 1 and the distance between the inner end of the tear tape 2 and the inner edge 1-2 of the fin seal 1. The outer part of the tear tape 2 extending outside from the outer edge 1-1 of the fin seal 1 may have any length, provided that the outer part of the tear tape 2 can be easily held between fingertips. Preferably, the length of the outer part of the tear tape 2 is in the range of about 5 to 15 mm. The distance between the inner end of the tear tape 2 and the inner edge 1-2 of the fin seal 1 is important because this distance affects the sealing performance of the packaging bag.
A tear tape holding part of the fin seal 1 holding the tear tape 2 is thicker than other parts continuous with the tear tape holding part and not holding the tear tape 2 by a thickness corresponding to that of the tear tape 2. Therefore, steps of a height corresponding to the thickness of the tear tape 2 are formed at boundaries between the tear tape holding part and the other parts continuous with the tear tape holding part. Application of pressure to the stepped parts of the fin seal 1 is difficult when the side edge parts of the plastic film and the tear tape 2 sandwiched between the side edge parts are fusion-bonded to form the fin seal 1 holding the tear tape 2. If height of the stepped part is excessively large, spaces formed in the stepped parts cannot be stably and completely filled up with the melted fusible film 10 and defective sealing of the packaging bag is liable to occur.
It is preferable that the inner end of the tear tape 2 is at a distance on the inside from the inner edge 1-2 of the fin seal 1 to prevent the defective sealing of the packaging bag even if the stepped parts of the fin seal 1 are not completely sealed. When the inner end of the tear tape 2, namely, the end of the inner part, held in the fin seal 1, of the tear tape 2, is on the inside of the inner edge 1-2 of the fin seal 1, the tear tape 2 does not extend in a part, between the inner end of the tear tape 2 and the inner edge 1-2 of the fin seal 1, of the fin seal 1, namely, a part on the inward extension of the tear tape 2, and hence parts, between the inner end of the tear tape 2 and the inner edge 1-2 of the fin seal 1, of the side edge parts 3-1 and 3-2 can be directly bonded together and the packaging bag can be sealed satisfactorily.
More specifically, it is preferable that the inner end of the tear tape 2 is at a distance X (Fig. 12) in the range of 2 to 8 mm from the inner edge 1-2 of the fin seal 1. The entire length of the tear tape 2 is 21 mm when the length of the outer part of the tear tape 2 is 10 m, the width of the fin seal 1 is 15 mm and the distance between the inner end of the tear tape 2 and the inner edge 1-2 of the fin seal 1 is 4 mm.
The easily tearable parts 5, namely, tear initiating parts, are formed in the outer edge 1-1 of the fin seal 1 on the opposite sides of the tear tape 2 or near the tear tape 2. Two cuts, such as slits or notches, may be formed in parts, contiguous with the side edges of the tear tape 2, of the outer edge 1-1 or in parts near the parts contiguous with the side edges of the tear tape 2 when the packaging bag is fabricated. The easily tearable parts. The easily tearable parts 5 may be formed successively in the outer edge 1-1 over the entire length of the outer edge 1-1 as shown in Fig. 12 by pressing a cutting tool, made by arranging small cutters on the circumference of a roll, mentioned in JP 61-142133 A or a tool formed by attaching small abrasive grains on the circumference of a roll against the plastic film 3 before or after shaping the plastic film 3 into the packaging bag.
When the two cuts are formed in the outer edge 1-1 on the outside of the side edges of the tear tape 2, the packaging bag needs to be fabricated carefully so that the two cuts are formed accurately in parts, contiguous with the side edges of the tear tape 2, of the outer edge 1-1 or in parts near the parts contiguous with the side edges of the tear tape 2. The easily tearable parts 5 may be formed in the outer edge 1-1 over the entire length of the outer edge 1-1 without paying any particular attention to the positional relation between the tear tape 2 and the easily tearable parts 5.
Figs. 13A and 13B are sectional views of the easily openable packaging bag at a first stage after the start of unsealing the bag and at a second stage after the start of unsealing the packaging bag, respectively, and Fig. 14 is a plan view of the easily openable packaging bag shown in Figs. 13A and 13B. At the start of opening the packaging bag of the present invention, the tear tape 2 is held between fingertips and is pulled in the direction of the arrow e as shown in Fig. 13A. Since the tear tape 2 is fusion-bonded integrally to the over layer 3-1 and the under layer 3-2 of the fin seal 1, the fin seal 1 starts being torn from parts of the outer edge 1-1 corresponding to the side edges of the tear tape 2 or the easily tearable parts 5 formed in the outer edge 1-1 at positions on the outside of both the side edges of the tear tape 2. A part of the fin seal 1 is torn off in a strip along tear lines f-1 and f-2. Upon the propagation of tears to positions corresponding to the inner edge 1-2 of the fin seal 1, a tensile stress is induced in the under layer 3-2.
Since the easily breakable part 6 having a low strength is formed in the under layer 3-2 in the vicinity of the inner edge 1-2 of the fin seal 1. Upon the increase of the tensile stress induced in the easily breakable part 6 beyond the strength of the easily breakable part 6, a part, on the inside of the inner edge 1-2 of the fin seal 1 and not fusion-bonded to the upper layer 3-1, of the easily breakable part 6 breaks as shown in Fig. 13B. Subsequently, only an annular part of the upper layer 3-1 is torn off the bag body as the tear tape 2 is pulled. Finally, the packaging bag is divided into three parts, namely, a strip 12 and two half bodies 11-1 and 11-2, as shown in Fig. 9.
In the packaging bag shown in Figs. 13 and 14, the easily breakable part 6 extends between a part, fusion-bonded to the upper layer 3-1, of the under layer 3-2 and a part, not fusion-bonded to the upper layer 3-1, of the under layer 3-2. The easily breakable part 6 does not need necessarily to be formed like that shown in Figs. 13 and 14, provided that the width A (Fig. 12) of a part, extending beyond the inner edge 1-2 of the fin seal into the not fusion-bonded part of the under layer 3-2, of the easily breakable part 6 is in the range of 1 to 10 mm.
The easily breakable part 6 may be extended over the entire length of the inner edge 1-2 the fin seal 1 to simplify the easily breakable part forming process and to make accurate positioning of the tear tape on the fin seal unnecessary. However, it is preferable, in view of the mechanical strength of the packaging bag, that the easily breakable part 6 is extended only in a necessary part of the under layer 3-2 over a length along the inner edge 1-2 as shown in Figs. 13 and 14. The size of the easily breakable part 6 may be determined taking into consideration the positional accuracy of the tear tape so that the easily breakable part 6 is sure to lie on the extension of the tear tape 2. Preferably, the width Y (Fig. 12) of the easily breakable part 6 along the length of the inner edge 1-2 of the fin seal 1 is in the range of 1.5 to 4 times the width of the tear tape 2.
Since the tear tape 2 is pulled in a direction in which the tear tape 2 extends in the fin seal 1, the easily breakable part forming process is effective. A first easily breakable part forming method forms minute fissures in the base film 8 before laminating the component films 8, 9 and 10 of the plastic film 3 shown in Fig. 10 by pressing a cutting tool made by arranging small cutters on the circumference of a roll or a roughening tool formed by attaching small abrasive grains on the circumference of a roll against the base film 8. A second easily breakable part forming method forms minute fissures in the base film 8 and the intermediate film 9 individually before laminating the component films 8, 9 and 10 of the plastic film 3 shown in Fig. 10 by pressing the cutting tool or the roughening tool against the base film 8 and the intermediate film 9. A third easily breakable part forming method forms minute fissures in the base film 8 and the intermediate film 9 laminated to the base film 8 before laminating the fusible film 10 to the intermediate film 9 by pressing the cutting tool or the roughening tool against the base film 8 and the intermediate film 9. The third easily breakable part forming method is preferable because minute fissures formed by the third easily breakable part forming method penetrate the laminated plastic film 3 and the easily breakable part 6 provided with such fissures is easily breakable.
To form the easily breakable part 6 in a predetermined part of a length along the inner edge 1-2 of the fin seal 1, a registration mark is printed beforehand on the base film, a sensor detects the registration mark, the sensor sends a signal upon the detection of the registration mark to a controller, the controller provides a control signal on the basis of the signal received from the sensor to control a servomotor, the servomotor drives a rotary tool, namely, the cutting tool or the roughening tool, having a circumference equal to an integral multiple of a predetermined pitch according to the control signal.
The pillow type easily openable packaging bag of the present invention is provided with the tear tape capable of being easily visually recognized and easily held between fingertips, is excellent in sealing performance, and is capable of being subjected to a heating process, such as a boiling process and of being unsealed by tearing off an annular part of the bag body. Thus, the easily openable packaging bag is suitable for containing a piece of konnyaku, namely, a jelly-like food or a jelly in a tight package and for containing contents that need to be processed by a heating process, such as a boiling process.

Examples

A 15 µm thick biaxially oriented polyethylene terephthalate resin film having one heat-sealable surface (Merinex 850, Teijin DuPont Film) as a base film, a 7 µm thick aluminum foil, and a laterally linearly tearable 17 µm thick high-density polyethylene film (Kararian Y, Toyo Kagaku) were laminated in that order and were bonded together with a two-part urethane adhesive to form a three-layer laminated film.
Rectangular easily breakable parts of 10 mm in width and 20 mm in length were formed at pitches of 120 mm in a longitudinal arrangement with respect to a direction in which the laminated film runs by an easily breakable part forming process. The easily breakable part forming process used an easily breakable part forming tool formed by attaching grains of a grain size #60 to two diametrically opposite parts having a circumferential length of 20 mm of the circumference of a metal disk of 10 mm in thickness and 76.4 mm in diameter. The laminated film was compressed between the easily breakable part forming tool and a bearing roller of a metal to form the easily breakable parts provided with minute fissures penetrating the laminated film.
Registration marks were printed beforehand at pitches of 120 mm on the base film, namely, the polyethylene terephthalate film to form the easily breakable parts at pitches of 120 mm. A sensor sent a detection signal to a controller upon the detection of the registration mark, and then the controller provided a control signal to control a servomotor for the fine adjustment of the rotation of the easily breakable part forming tool.
Subsequently, a 15 µm thick straight-chain, low-density polyethylene resin film of 0.917 g/cm³ and a 20 µm thick straight-chain low-density polyethylene resin film of 0.920 g/cm³ were extruded in that order through T-dies by a tandem extruder onto the intermediate film, namely, the Karadian Y, of the laminated film processed by the easily breakable part forming process to form a five-layer laminated film. The five-layer laminated film was cut into 129 mm wide slit films such that the middle of the width of 10 mm of the easily breakable part of each slit film is at 15 mm from an edge of the slit film.
A rotary cutting tool formed by arranging small cutters on the circumference of a metal roll of 5.5 mm in thickness was pressed against the central part of a slit line to form small easily tearable parts successively arranged in a direction in which the five-layer laminated film runs. Then, the five-layer laminated film was slit to obtain a slit film provided with the easily tearable parts in its side edges.
The slit film was processed by a gusset bag forming machine to form a gusset bag having a fin seal of 15 mm in width, opposite folded ends of 8.5 mm in depth, a lateral sealed end parts of 3 mm in width, a skirt of 4 mm in length and one open longitudinal end. The fin seal was bent toward the easily breakable part down on and lightly bonded to the bag body. A tear tape of 17 mm in length and 7 mm in width was formed by cutting a laminated film formed by laminating 25 µm thick low-density polyethylene resin films to the opposite surfaces of a 25 µm thick biaxially oriented polyethylene terephthalate resin film, respectively. The tear tape was inserted in a part, corresponding to the middle of the 20 mm long easily breakable part, of the fin seal and was bonded to the fin seal by fusion-bonding. An outer part of 7 mm in length of the tear tape was extended outside from the outer edge of the fin seal perpendicularly to the outer edge of the fin seal. The position of the tear tape was adjusted with reference to the registration marks used for determining the positions of the easily tearable parts and detected by the sensor.
The inner end of the tear tape inserted in the fin seal was at 5 mm on the inside of the inner edge of the fin seal. One of 5 mm wide parts of the 10 mm wide easily breakable part was included in the fin seal and the other was included in a not bonded part of the bag body. A jelly of konnyaku was filled in thus formed 500 gusset bags each provided with the tear tape and having one open end, the open ends were sealed to finish packages. The packages were put in a retainer and were subjected to a heating process to heat the same at 85°C for 30 min in hot water. Any of the 500 packages was not broken during the heating process. The 500 packages were dried. The 500 packages were examined immediately after drying and one week after drying. Any of the 500 packages was not broken and the contents leaked from none of the 500 packages.
The outer part of the tear tape was held between fingertips and was pulled in a direction perpendicular to the fin seal so as to raise the fin seal. About 7 mm wide parts of the upper and the under layer of the fin seal were torn off from the minute fissures near the side edges of the tear tape. Resistance against the pull of the tear tape increased temporarily upon the propagation of tears to the inner edge of the fin seal, the easily breakable part of the under layer was broken, and then an annular part of the bag body was torn off. The unsealed packaging bag was divided into three pieces, namely, a 7 mm wide strip and two half bag bodies, and the jelly of konnyaku could be easily taken out without being destroyed.
The pillow type easily openable packaging bag of the present invention is provided with the tear tape inserted in and fusion-bonded to the fin seal with the outer part thereof extended outside. Therefore, the easily openable packaging bag is satisfactory in sealing performance and can be subjected to a heating process, such as a boiling process. Since the tear tape is capable of being easily visually recognized and easily held between fingertips, an annular part of the bag body can be torn off by pulling the tear tape to open the packaging bag. Thus, the easily openable packaging bag is suitable for containing contents in a tight package.
An easily openable packaging bag in a second embodiment according to the present invention will be described with reference to Figs 15 and 16.
Fig. 15 is a perspective view of the easily openable bag in the second embodiment applied to a chewing gum package 101. The chewing gum package 101 has a box-shaped case 102 formed from a plastic film. Sticks of chewing gum, not shown, are contained in the case 102.
The contents contained in the box-shaped case 102 are not limited to sticks of chewing gum; the box-shaped case 102 is capable of holding any contents therein, provided that the contents are formed in a shape conforming to the box-shaped case 102.
The box-shaped case 102 is formed by folding a rectangular laminated packaging film in a rectangular tube, joining opposite side edge parts, namely, an over layer 103a and an under layer 103b, of the rectangular laminated packaging film in a fin seal 103 and sealing the opposite ends of the rectangular tube in sealed end parts 104. The fin seal 103 and the sealed end parts 104 are bent down on a case body 109 of the box-shaped case 102. Each of the sealed end parts 104 is formed by folding down an end part of the box-shaped case 102 along four sides 104a, 104b, 104c and 104d, and fusion-bonding the folded end part. Rectangular seals 105 are attached adhesively to the sealed end parts 104, respectively.
As shown in Fig. 15, the outer edge of the fin seal 103 of the box-shaped case 102 is provided in parts near one of the sealed end parts 104 with two notches 106 spaced a distance in the range of 5 to 15 mm apart from each other. A tear tab 108 is formed by tearing off a part of the fin seal 103 from the notches 106 along imaginary lines 107 extending from the notches 106.
The imaginary lines 107 extending from the notches 106 of the box-shaped case 102 extend parallel to each other from one side of the fin seal 103 round the case body 109 to the other side of the fin seal 103. The imaginary lines 107 extending round the case body 109 define a peel-off part 110 extending round the box-shaped case 102.
A tear tape 111 is attached adhesively to the inner surface of the case body 109 of the box-shaped case 102 so as to correspond to the peel-off part 110 as shown in Fig. 16. The tear tape 111 extends from the inner edge of the over layer 103a of the fin seal 103 round the case body 109 to the inner edge of the under layer 103b of the fin seal 103. A gap is formed in the tear tape 111 at a position corresponding to the fin seal 103. The tear tape 111 is about 40 µm in thickness and has a width in the range of 5 to 15 mm. Preferably, the center line of the tear tape 111 coincides with that of the tear-off part 110.
As shown in Fig. 16, a plastic film 109a (surface layer) forming the box-shaped case 102 has an easily breakable part 112 extending from a part, on the outside of the inner edge of the under layer 103b, of the under layer 103b to a part of the plastic film 109a forming the box-shaped case 102. The easily breakable part 112 has a width greater than that of the tear-off part 110 and extends across the tear-off part 110. The tear-off part 110 is defined by, for example, perforations.
Although the easily breakable part 112 extends from a part, on the outside of the inner edge of the under layer 103b, of the under layer 103b to a part of the plastic film 109a forming the box-shaped case 102 in the example shown in Fig. 16, the easily breakable part 112 may be formed in an narrow area between the inner edge of the under layer 103b and the end of the tear tape 111.
Preferably, a laminated plastic sheet forming the box-shaped case 102 is a laminated film resistant to breakage, such as a laminated film formed by laminating a 20 µm thick biaxially oriented polypropylene resin film and a 25 µm thick unoriented polypropylene resin film or a laminated film formed by laminating a 12 µm thick polyester resin film, a 15 µm thick polyethylene film, a 7 µm thick aluminum foil and a 25 µm thick polyethylene resin film.
The use of the chewing gum package 101 will be described.
In the chewing gum package 101 on the market, the fin seal 103 of the box-shaped case 102 is bent down on the case body 109 of the box-shaped case 102 as shown in Fig. 15.
When a person desires to break the chewing gum package 101 to take out a stick of chewing gum, the person raises up the fin seal 103 from the case body 109, holds a tear initiating part, between the two notches 106, of the fin seal 103 and pulls the tear initiating part in a direction parallel to the surface of the case body 109, i.e., to the right, as viewed in Fig. 16.
As the tear initiating part is pulled in the direction parallel to the surface of the case body 109, tears are initiated from the notches 106 and propagate in the fin seal 103 along the imaginary lines 107 to form the pull tab 108.
The pull tab 108 is pulled in the direction parallel to the surface of the case body 109. Consequently, the tears propagate along the imaginary lines 107 to the inner edge of the fin seal 103 continuous with the case body 109. Since the easily breakable part 112 extends across the tear-off part 110 from a part, on the outside of the inner edge of the under layer 103b, of the under layer 103b to a part of the plastic film 109a forming the box-shaped case 102, the inner edge of the fin seal 103 can be easily broken by a low force.
The pull tab 108 is pulled further. Then, since the inner edge of the fin seal 103 is broken, the tear tape 111 tears the case body 109 of the box-shaped case 102 along the imaginary lines 107 to open the chewing gum package 101 by tearing off the tear-off part 110. A stick of chewing gum contained in the box-shaped case 102 can be taken out of the box-shaped case 102 through an open end of the box-shaped case 102.
Although the he tear-off part 110 of this chewing gum package 101 is defined by the perforations, it is preferable that the tear-off part 110 is a narrow strip having a roughened surface formed by pressing a piece of sandpaper against a part of the surface of the biaxially oriented propylene resin film to ensure the satisfactory sealing performance of the chewing gum package 101.
The box-shaped case of the chewing gum package 101 can be opened by tearing off the tear-off art along the linear tears by a low force regardless of the properties of the plastic film forming the box-shaped case to take out the contents easily from the box-shaped case.

Claims

An easily openable packaging bag comprising:

a tubular bag body formed by folding a plastic film, fusion-bonding superposed opposite side edge parts of the plastic film in a fin seal consisting of an over layer and an under layer, and fusion-bonding the opposite open ends of the tubular bag body; and

a tear tape inserted between the over and the under layer of the fin seal and fusion-bonded at least at a position on the fin seal together with the opposite side edge parts of the plastic film forming the over and the under layer of the fin seal so that an outer end part thereof extends outside;

wherein tear initiating parts are formed in parts of the outer edge of the fin seal near and on the outside of the side edges of the tear tape, and an easily breakable part is formed in a part, continuous with the under layer of the fin seal, of the tubular bag body, on a longitudinal extension of the tear tape and a part, extending from the inner edge of the fin seal, of the tubular bag body.
The easily openable packaging bag according to claim 1 is a gusseted bag provided with gussets in opposite ends thereof.
The easily openable packaging bag according to claim 1,
wherein an inner end part of the tear tape is held in the fin seal such that the end edge thereof is at a distance in the range of 2 to 8 mm into the fin seal from the inner edge of the fin seal.
The easily openable packaging bag according to claim 1,
wherein the plastic film is formed by laminating a base film, an intermediate film and a fusible film in that order.
The easily openable packaging bag according to claim 4,
wherein the intermediate film is tearable such that tears propagate in a tear propagation direction perpendicular to a direction in which the fin seal extends.
The easily openable packaging bag according to claim 4,
wherein the base film and the intermediate film are processed by an easily breakable part forming process to form minute fissures penetrating the base film and the intermediate film laminated to the base film.
The easily openable packaging bag according to claim 1,
wherein the plastic film is formed by laminating a base film, a barrier film, an intermediate film and a fusible film in that order.
The easily openable packaging bag according to claim 7,
wherein the barrier film is an aluminum foil.
The easily openable packaging bag according to claim 7,
wherein the base film, the barrier film and the intermediate film are processed by an easily breakable part forming process after lamination to form minute fissures penetrating the base film, the barrier film and the intermediate film.
The easily openable packaging bag according to claim 1, wherein the easily breakable part forming process presses a tool capable of forming minute fissures against the films.
The easily openable packaging bag according to claim 10, wherein the minute fissures are formed by pressing abrasive grains against the films.
The easily openable packaging bag according to claim 10, wherein the minute fissures are minute cuts formed by pressing a cutting tool against the films, and extending parallel to the inner edge of the fin seal.
the easily openable packaging bag according to claim 1,
wherein only parts, having a width equal to 1.5 to 4 times the width of the tear tape, of the films on an extension of the tear tape are processed by the easily breakable part forming process.
The easily openable packaging bag according to claim 1, wherein the easily breakable part forming process forms the easily breakable part at least in a part between the fin seal and an unbonded part at a distance in the range of 1 to 10 mm from the inner edge of the fin seal.
The easily openable packaging bag according to claim 1, wherein the easily tearable part forming process forms many, minute, elongate, fissures extending substantially perpendicularly to the outer edge of the fin seal in a successive arrangement along the length of the fin seal.
The easily openable packaging bag according to claim 1, wherein a part, corresponding to the tear tape, of the fin seal is fusion-bonded over the entire width thereof.
The easily openable packaging bag according to claim 4 or 7, wherein the base film is a single-sided sealable film, and the fin seal is fusion-bonded to the tubular bag body by partial coating.
An easily openable packaging bag comprising:

a box-shaped case having a case body formed by folding a plastic film, fusion-bonding superposed opposite side edge parts of the plastic film in a fin seal consisting of an over layer and an under layer, forming two notches in the fin seal, sealing opposite ends of the case body in opposite sealed ends, and bending down the fin seal and the opposite open ends on the case body; and

a tear tape circumferentially extended on the inner surface of a tear-off part forming part, demarcated by parallel imaginary lines extending from the two notches between a position near the inner edge the over layer of the fin seal and a position near the inner edge of under layer of the fin seal, of the case body of the box-shaped case;

wherein an easily breakable part is formed so as to extend across the tear part forming part between the under layer of the fin seal and an unbonded part of the case body of the box-shaped case.
The easily openable packaging bag according to claim 18, wherein the easily breakable part are perforations.
The easily openable packaging bag according to claim 18, wherein the easily breakable part has a narrow width and a roughened surface.
The easily openable packaging bag according to claim 18, wherein the tear tape has a width smaller than that of the tear-off part forming part.