HK1066511B

HK1066511B - Method for manufacturing packaging bag

Info

Publication number: HK1066511B
Application number: HK04109434.1A
Authority: HK
Inventors: 市川彻
Original assignee: 株式会社细川洋行
Priority date: 2002-11-27
Filing date: 2004-11-30
Publication date: 2009-05-22

Description

Method for producing packaging bags

Technical Field

The present invention relates to a packaging bag in which a bag body can be held in a predetermined shape by a frame member, and a method of producing such a packaging bag.

Background

There have been conventionally provided packaging bags made of various plastic film materials. Recently, there has been a strong demand for packages that can accommodate products such as tea bags having a predetermined shape without folding their shape. The applicant has endeavored to develop a package that addresses the above needs. Such a packaging bag comprises a bag body made of a plastic film material and a liner disposed in the bag body. The liner may be folded/unfolded and inserted into the bag body from an opening of the bag body. The sleeve received in the bag body can thus be folded/unfolded together with the bag body, so that the sleeve and the bag body can be changed between a substantially flat folded state and an expanded state. Japanese patent laid-open application No2001322187 discloses such a packaging bag and the technical effects provided by the packaging bag.

In the above-described packaging bag, a liner having an appropriate size is placed in an appropriate position of the bag body so as to provide a good appearance of the packaging bag in an inflated state.

However, it is not easy to insert a liner having an appropriate size into the bag body from the opening of the bag body. More specifically, when the length of the opening of the bag body in the flat folded state is the same as the width of the liner sleeve also in the flat folded state, the overall thickness of the flat folded liner sleeve makes it difficult to insert the liner sleeve into the bag body because there is no gusset. The linear fastening means makes the insertion operation of the liner more difficult when the bag body is provided with a linear fastening means in its opening. Such difficulty in the insertion operation of the liner deteriorates the production efficiency of the packing bag, thus resulting in an increase in the manufacturing cost of the packing bag.

It is conceivable to reduce the size of the liner so as to ease the operation of inserting the liner into the bag body. In this case, the liner maintaining the expanded state is gap-fitted into the bag body maintaining the same expanded state to create a large gap between the liner and the body, thereby spoiling the appearance of the packaging bag.

Disclosure of Invention

An object of the present invention, which solves the above problems, is to provide a packaging bag which allows easy production thereof, thus reducing the manufacturing cost, and which provides a good appearance in an inflated state, and a method for manufacturing such a packaging bag.

In order to solve the above-described problems, a packaging bag according to a first aspect of the present invention includes:

forming a bag body of a plastic film material through a bag body forming process, the bag body having an opening and a plurality of heat-sealed portions; and

a frame member disposed within said bag body, said frame member being attached to said bag body prior to completion of said bag body forming process, said frame member being foldable and unfoldable with said bag body to allow said frame member and said bag body to be converted between a generally flat folded condition and an expanded condition.

The above-described packing bag may further comprise a linear fastening means provided on the opening of the bag main body.

In the above-described packaging bag, the bag body may have a rectangular shape in a substantially flat folded state, the bag body being provided with a pair of heat-seal portions on opposite sides thereof.

In the above-described package, the frame member may include a pair of opposed reinforcing portions, each of the reinforcing portions having a rectangular shape with a first pair of opposed side edges and a second pair of opposed side edges, the first pair of opposed side edges being embedded in the pair of heat-seal portions.

In the above-described bag, the second pair of opposed side edges may be bonded to the bag body at a region other than where the pair of heat-sealed portions are processed.

In the above-described packaging bag, the frame member may include a pair of opposed reinforcing portions, each of the reinforcing portions having a rectangular shape with a first pair of opposed side edges and a second pair of opposed side edges, the first pair of opposed side edges and the second pair of opposed side edges being bonded to the bag body in a region other than the pair of heat-seal portions.

In order to solve the above object, according to a second aspect of the present invention, a method for producing a pack includes the steps of:

(a) continuously supplying in a longitudinal direction a single strip of thermoplastic film material for a bag body, said single strip having opposite halves between which there is a longitudinal centerline of said single strip;

(b) continuously feeding a pair of strips of sheet material for a framing element, said pair of strips for the framing element being placed on a surface of said unique strip for said bag body in predetermined positions of respective opposite halves of the unique strip;

(c) -gluing said pair of strips for the frame element to said unique strip for the bag body in the corresponding half;

(d) folding said unique strip for the bag body in half along the midline of said unique strip for the bag body with said paired strips for the frame element to bring one of said opposed halves of the unique strip for the bag body adjacent the other of said opposed halves to prepare a folded composite strip such that said paired strips for the frame element are disposed inwardly of said folded composite strip;

(e) heat-bonding said folded composite strip at predetermined intervals in a direction perpendicular to the longitudinal direction thereof so as to form heat-sealed portions; and

(f) cutting each heat-sealed portion in two in a direction perpendicular to the longitudinal direction of said folded composite strip,

thereby continuously producing a plurality of packing bags each including the bag main body and the frame member which can be folded/unfolded together with the bag main body, thereby allowing the frame member and the bag main body to be changed between a substantially flat folded state and an expanded state.

In the above method, the steps (a) to (f) may be manufactured on a production line.

The above method may further comprise the steps of:

(g) forming an easily bendable portion on each of said pair of strips for the frame member so as to extend in a direction perpendicular to a feeding direction of said pair of strips for the frame member, prior to said step (b).

In the above method, the steps (a) to (g) may be manufactured on a production line.

In order to solve the above-mentioned object, a method according to a third aspect of the present invention for producing a pack includes the steps of:

(a) continuously supplying a pair of strips of thermoplastic film material for a bag body in a longitudinal direction so that they are spaced from each other;

(b) continuously feeding a pair of strips of sheet material for a framing element to place said pair of strips for the framing element in predetermined positions on respective inner surfaces of said pair of strips for said bag body;

(c) bonding said pair of strips for the frame element to said pair of strips for the bag body, respectively;

(d) bringing one of said pair of strips for the bag body close to the other of said pair of strips for the bag body, thereby causing said pair of strips for the frame element to oppose each other, thus preparing a set of composite strips;

(e) thermally bonding said composite strip set at predetermined intervals in a direction perpendicular to the longitudinal direction thereof to form side heat-sealed portions;

(f) heat bonding said composite strip set at one longitudinal edge thereof to form a bottom heat seal; and

(g) cutting said heat-sealed portions into two in a direction perpendicular to the longitudinal direction of said composite strip set,

thereby continuously producing a plurality of packing bags each including the bag main body and the frame member foldable/unfoldable together with the bag main body so as to shift the frame member and the bag main body between a substantially flat folded state and an expanded state.

In the above method, the steps (a) - (g) may be performed on a production line:

the above method further comprises the steps of: (h) forming a flexible portion on either one of said pair of strips for the frame member so as to extend in a direction perpendicular to a feeding direction of said pair of strips for the frame member, prior to said step (b).

In the above method, the steps (a) - (h) may be performed on a production line.

In order to solve the above object, the method according to the fourth aspect of the present invention for producing a packaging bag comprises:

(a) preparing a single sheet of plastic film for a bag body, said single sheet

Having opposite halves between which there is a midline of the sole sheet;

(b) placing a pair of sheets of sheet material for a frame element on a surface of said unique sheet for the bag body at predetermined locations of respective opposite halves of the unique sheet;

(c) bonding said pair of sheets for the frame element to said unique sheet for the bag body in respective opposite halves of the unique sheet;

(d) folding said unique sheet for the bag body in half with said pair of sheets for the frame element along said midline of said unique sheet for the bag body, thereby bringing one of said opposing halves of said unique sheet for the bag body adjacent the other to prepare a folded composite sheet such that said pair of sheets for the frame element is disposed inside said folded composite sheet; and

(e) the folded composite sheet is thermally bonded on opposite side edges thereof to form heat-sealed portions,

thereby forming the package comprising the bag body and the frame member which together with said bag body can be folded/unfolded for shifting said frame member and said bag body between a substantially flat folded condition and an expanded condition.

The above method may further comprise the steps of:

(f) forming a flexible portion on each of said pair of sheets for the frame member prior to said step (b).

In order to solve the above object, the method according to the fifth aspect of the present invention for producing a pack bag comprises the steps of:

(a) providing a pair of sheets of plastic film material for a bag body spaced from one another;

(b) placing a pair of sheets of thin sheet material for a frame member in predetermined positions on respective inner surfaces of said pair of sheets for the bag body;

(c) bonding said pair of sheets for the frame member to said pair of sheets for the bag body, respectively;

(d) bringing one of said pairs of sheets for the bag body close to the other so as to face said pairs of sheets for the frame element to each other, thus preparing a set of composite sheets; and

(e) heat bonding the opposed side edges and opposed bottom edges of said composite sheet pack to form side heat seal portions and a bottom heat seal portion;

thereby producing the packing bag comprising the bag body and the frame member which can be folded/unfolded together with the bag body so that the frame member and the bag body are changed between a substantially flat folded state and an expanded state.

The above method further comprises the steps of: (f) forming a flexible portion on each of said pair of strips for the frame member prior to said step (b).

In order to solve the above object, the method according to the sixth aspect of the present invention for producing a pack bag comprises the steps of:

(a) providing a pair of sheets of plastic film material for a bag body so as to be spaced from each other;

(b) positioning a frame member forming a sleeve in a predetermined position on respective inner surfaces of said pair of sheets for the bag body;

(c) said frame members being respectively bonded to said pair of sheets for the bag body;

(d) bringing one of said pair of sheets for the bag body close to the other so as to accommodate said frame element between said pair of sheets for the bag body, thus preparing a set of composite sheets; and

(e) heat bonding the opposed side edges and opposed bottom edges of said composite sheet pack to form side heat seal portions and bottom heat seal portions;

The above method further comprises the steps of: (f) forming a flexible portion on said frame member prior to said step (b).

Drawings

FIG. 1 is a front view of a package according to an embodiment of the present invention;

FIG. 2 is a perspective view showing the package with a frame member in an expanded state and a bag body deformed accordingly;

FIG. 3 is a partial perspective view showing the packing bag in which the lower portion of the bag body downwardly protruding from the lower end of the frame member is folded to form a bottom;

FIG. 4 is a perspective view of a package provided with a base as shown in FIG. 3;

FIG. 5 is a perspective view showing the packing bag in which the upper portion of the bag body upwardly protruding from the upper edge of the frame member is folded into a flat state after the packing bag is filled with the contents;

FIG. 6 is a perspective view showing the packing bag, wherein the opposite edges of the upper portion of the bag main body horizontally protruding from the upper edge of the frame member as shown in FIG. 5 are further folded to be in contact with the opposite sides of the packing bag, respectively, thereby providing a rectangular parallelepiped;

FIG. 7 is a perspective view showing a strip of plastic film for forming the body of the bag on which a set of male elements and a set of female elements for forming the linear fastening means are provided when unwinding the strip of plastic film;

FIG. 8 is a perspective view showing a pair of strips of plastic film material used to form the frame member, which are subjected to a step of forming a readily bendable portion so as to form the readily bendable portion thereon, and then advanced so as to oppose each other;

FIG. 9 is a partial cross-sectional view showing a roller having a projection for carrying out the step of forming the readily bendable portion, and the readily bendable portion being formed on the strip of plastic film by the projection;

FIG. 10 is a simplified diagram showing a step for doubling back the unique strip for a bag body and the paired strips for the frame member together along the longitudinal centerline of the unique strip for a bag body;

FIG. 11 is a simplified view showing a step for forming heat-seal portions by heat-bonding a single strip for the bag main body and a composite strip for the paired strips of the main body at predetermined intervals in a direction perpendicular to the longitudinal direction of the paired strips of the frame member;

FIG. 12 is a simplified diagram showing the steps for cutting each heat-sealed portion in two in a direction perpendicular to the longitudinal direction of the folded composite strip;

FIG. 13 is a perspective view showing a packaging bag produced by the method according to another embodiment of the present invention;

FIG. 14 is a perspective view showing the package shown in FIG. 13 inverted;

FIG. 15 is a perspective diagrammatic view showing the steps for continuously feeding a pair of strips of plastic film material for the bag body, while continuously feeding a pair of strips of sheet material for the framing element for placing the pairs of strips for the framing element onto respective inner surfaces of the pairs of strips for the bag body;

fig. 16 is a perspective sketch showing a step for heat-bonding a set of paired strips for the bag body and paired composite strips for the strips of the frame element at predetermined intervals in a direction perpendicular to the direction of the paired strips of the frame element, thereby forming side heat-seal portions, a step for heat-bonding the set of composite strips on the longitudinal edges of the set of composite strips to form a bottom heat-seal portion, and a step for cutting each heat-seal portion into two in a direction perpendicular to the longitudinal direction of the set of composite strips;

FIG. 17 is a plan view showing the package in a flat folded condition, which has been produced by completing the steps shown in FIG. 16;

FIG. 18 is a simplified partial view showing a modification of the method of the present invention in which a group of 3 packages may be disposed in a region of the group of composite strips extending in a direction perpendicular to the direction of feed of the group of composite strips;

FIG. 19 is a simplified diagram showing some steps of the improvement of FIG. 18;

FIG. 20 is a simplified diagram illustrating a method of another embodiment of the present invention using a single sheet of plastic film for the bag body and a pair of sheets of thin sheet material for the frame member to produce a single package;

FIG. 21 is a simplified diagram illustrating a method for producing the unique package using a pair of plastic film sheets for the bag body and a pair of thin sheet material sheets for the frame member in accordance with other embodiments of the present invention; and

fig. 22 is a simplified diagram illustrating a method of other embodiments of the present invention using a pair of plastic film sheets for the bag body and a sleeve serving as a frame member to produce the unique package.

Detailed Description

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 shows a schematic view of a package 1 according to a first embodiment of the invention. The packaging bag 1 comprises a bag body 2 and a frame element 10, the frame element 10 being connected to the bag body 2 and being foldable/unfoldable together with the bag body 2 before completion of the bag body 2, such that the frame element 10 and the bag body 2 are transformed between a substantially flat state and an expanded state.

More specifically, the bag body is made of a plastic film by a bag body forming process of forming a rectangular shape in a substantially flat folded state. The bag body 2 is formed by folding a single rectangular sheet of plastic film material for the bag body along two midline lines to form a pair of opposed panel members 3, 3, and heat bonding the opposed side edges of the thus folded sheet to form side heat seal portions 4, 4. The bag body 2 has an opening at the side opposite the midline along which the sheet is folded in half. The bag body 2 is provided with a linear fastening means 5 at the opening. The linear fastening means 5 comprise an insertion element 5a formed on the inner surface of one of the panel elements 3, 3 at the above-mentioned opening and a receiving element 5b formed on the inner surface of the other of the panel elements 3, 3 at the opening. The insertion element 5a can be engaged with or disengaged from the receiving element 5b so that the bag body 2 is closed or opened.

The framing element 10 is made of a sheet material such as a plastic material or a plastic/paper composite. The frame member 10 includes a pair of opposed reinforcing portions which are thermally bonded to the inner surfaces of the panel members 3, 3. Each of the reinforcing portions has a rectangular shape. The position of the reinforcing portion with respect to the panel element 3 is determined so as to maintain a distance "L1" between the lower edge 13 of the reinforcing portion and the lower edge of the panel element 3 and a distance "L2" between the upper edge 12 of the reinforcing portion and the upper edge of the panel element 3, as shown in fig. 1. Each reinforcement portion has a first pair of opposing side edges (i.e., right and left side edges in fig. 1) and a second pair of opposing side edges (i.e., upper and lower side edges in fig. 1). The length of each of the upper and lower side edges of the reinforcing portion is substantially the same as the width of the bag body 2 so that the right and left side edges of the reinforcing portion are embedded in the side heat-seal portions 4, 4. Each of the upper and lower side edges of each reinforcing portion is thermally bonded to the inner surface of each of the panel members 3, 3 at regions other than the side heat-seal portions 4, 4.

Each of the reinforcing portions of the frame member 10 is provided with a pair of easily bendable portions 11, 11 extending in parallel with the side heat-seal portions 4, 4 at positions shifted inward from the right and left side edges of the bag body 2. The easily bendable portion 11 makes it easy for the reinforcing portion to be folded therealong, thus ensuring the folding/unfolding operation of the frame member 10.

The insertion element 5a of the linear fastening device 5 comprises 3 portions, namely a set of main portions and opposite side portions arranged in line spaced from each other as shown in fig. 7. The spacing between the central main portion and the opposing side portions is arranged so as to correspond to the aforementioned flexibility-permitting portions. The receiving element 5b of the linear fastening device 5 also comprises 3 similar parts as the insertion element 5 a. The clearance of either of the male 5a and female 5b members is such that the body can be easily folded in accordance with the transformation of the frame member 10 between the flat folded condition and the expanded condition.

The bag body 2 and the frame element 10 are designed such that the height of the frame element 10 is approximately the same as the height of the packaging bag 1, wherein the packaging bag 1 is transformed into an expanded state and subjected to a bending post-treatment step in order to provide a finished product in the shape of a rectangular parallelepiped. The frame element 10 is bent at right angles in the easily bendable sections 11, thus forming 4 side edges of the rectangular parallelepiped.

The plastic film material for the bag body 2 and the sheet material for the frame element 10 will now be given below.

A plastic laminate film having a plurality of layers is used to form the bag body 2. For example, a laminate film having a layer structure of an oriented polypropylene (OPP) layer having a thickness of 25 μm and a Polyethylene (PE) layer having a thickness of 50 μm thermally bonded to each other may be used. In this case, the bag body 2 is designed such that the oriented polypropylene layer is arranged on the inner side of the bag body 2. It is desirable to add an aluminum layer to the laminate film to improve barrier properties. In this case, a laminate film having a layer structure of an oriented polypropylene (OPP) layer having a thickness of 25 μm, an aluminum layer having a thickness of 5 μm, and a Polyethylene (PE) layer having a thickness of 50 μm, which are thermally bonded to each other, may be used.

The frame member 10 is formed using a plastic film having a predetermined strength such that the bag body 2 in an expanded state is appropriately held in a predetermined shape transformed together with the frame member. A Polyethylene (PE) film having a thickness of 100 microns is used for the frame element, for example.

The package 1 having the above-described structure is transformed from a substantially flat folded condition as shown in fig. 1, through the intermediate condition shown in fig. 2-5, to an expanded finished condition as shown in fig. 6.

First, the opposite sides of the envelope 1 in the substantially flat folded state are pressed inward in the direction indicated by the arrows in fig. 2, so that the pair of opposite reinforcing portions of the frame member 10 are folded at right angles along the easy-to-bend portions 11, thereby causing the frame member 10 to be transformed together with the envelope body 2 from the substantially flat folded state to the expanded state in the shape of a sleeve. Such pressing operation provides opposed front and back panel portions 8a, 8b and opposed side panel portions 6, 6. The pressing operation described above also provides an upper portion 3a projecting upwardly from the upper edge 12 of the frame member 10 and a lower portion 3b projecting downwardly from the lower edge 13 of the frame member 10. In this pressing operation, the side heat-seal lands 4, 4 are bent back.

The lower portion 3b projecting downwardly from the lower edge 13 of the frame member 10 is then folded along the lower edge 13 of the frame member 10 into a flattened condition so as to provide a pair of outwardly and generally horizontally extending triangular portions 7a, 7b as shown in phantom in figure 3. The triangular portions 7a, 7b are bent inwardly along the lower edge of the frame member 10 and the triangular portions 7a, 7b are thermally bonded to the corresponding portions as shown by the solid lines in fig. 3 to form the lower panel portion 7 of the packaging bag 1. Any other suitable adhesive may be used to bond the triangular portions 7a, 7b, and the portions 7a, 7b may be bonded to the respective portion by a suitable adhesive. The folding process of the lower portion 3b of the packing bag 1 forming the bottom panel portion 7 is completed in this manner. At this stage, the packing bag 1 is provided at its lower side with a lower portion of a box folded into a flat bottom having a substantially rectangular shape, and at its upper side with an upper portion 3a, the upper portion 3a projecting upward from the upper edge of the frame member 10 and being in a half-folded state in which the width of the upper portion 3a gradually increases with its height in a plan view of the packing bag 1, as shown in fig. 4.

The upper portion 3a, which projects upwardly from the upper edge of the frame member 10, is then also folded into a flattened condition along the upper edge 12 of the frame member 10 so as to provide a pair of outwardly and generally horizontally projecting trapezoidal portions 9a, 9b as shown in figure 5. In such a folding operation, the opening of the envelope 1 closed by the linear fastening means abuts against the back panel portion 8 b.

The pair of trapezoidal portions 9a, 9b are bent downwardly along the upper edge of the frame element 10 and are heat bonded to the opposite side panel portions 6, 6, respectively, thereby providing a finished product, as shown in fig. 6. The folding operation of the upper edge 3a of the package 1 to form the top panel portion 9 is accomplished in this manner. Any other suitable type of adhesive may be applied to the bonding of the trapezoidal sections 9a, 9b and the sections 9a, 9b may be bonded to the opposite side panel sections 6, 6 by a suitable adhesive. Of course, the folding process described above is performed after the envelope 1 is filled with the contents.

The package 1 transitioning from the generally flat, folded condition to the expanded condition provides the appearance of the box, the package 1 having opposed front and back panel portions 8a, 8b, side panel portions 6, 6, a bottom panel portion 7 and a top panel portion 9, wherein the opposed front and back panel portions 8a, 8b are in parallel opposition to each other, the side panel portions 6, 6 are also in parallel opposition to each other on opposed sides of the front and back panel portions 8a, 8b, the bottom panel portion 7 is completed by folding the bottom portion 3b of the package 1 into a flat condition, and the top portion is completed by folding the upper portion 3a of the package 1 into a flat condition. Each of these front and back panel portions 8a, 8b and side panel portions 6, 6 has a height that is approximately the same as the height of the frame member provided in the package 1. More specifically, on the one hand the lower edge 13 of the frame element 10 is formed with edges 1a, 1a, 1a, 1a between the front, rear and side panel portions 8a, 8b, 6, 6 and the bottom panel portion 7, and on the other hand the upper edge 12 of the frame element 10 is formed with edges 1c, 1c, 1c, 1c between the front, rear and side panel portions 8a, 8b, 6, 6 and the top panel portion 9. In addition, the bending of the frame element 10 provided by folding the frame element 10 along the easily bendable portion 11 forms edges 1b, 1b, 1b, 1b between the front and back panel portions 8a, 8b and the side panel portions 6, 6.

The packaging bag 1 can be transformed from the substantially flat folded condition to the expanded condition and then subjected to a folding operation so as to transform into a box shape corresponding to the frame element 10 in the expanded condition. It is thus possible to contain products such as tea bags having a predetermined shape in the package bag in an expanded state without collapsing their shape. The linear fastening means 5 provided at the opening of the packing bag 1 allows the packing bag 1 to be closed again even after the packing bag 1 is opened.

In the above-described packing bag 1 in the embodiment of the invention, each of the upper and lower side edges of each reinforcing portion of the frame member 10 is heat-bonded to the inner surface of each of the panel members 3, 3 at the other regions than the side heat-seal portions 4, 4. However, when a proper contact state of the reinforcing portion with the inner surfaces of the panel portions 3, 3 can be secured, or a possible gap existing between the reinforcing portion and the panel members 3, 3 does not cause any problem in the operation of filling the package with the contents, the upper and lower side edges of each reinforcing portion of the frame member 10 do not have to be thermally bonded to the inner surfaces of each panel member 3, 3 at other regions than the side heat-seal portions 4, 4.

The above-described packing bag 1 in the embodiment of the present invention is provided with the linear fastening device. Such linear fastening means may be omitted if the situation requires.

A method of the first embodiment of the present invention for producing the above-described packing bag 1 will now be described below with reference to fig. 7 to 12.

In a first embodiment of the method of the invention, a single strip 20 for the bag body 2 and pairs of strips 30, 30 for the frame element 10 are used to produce a plurality of packages 1.

More specifically, the method for producing the packaging bag comprises the following basic steps:

(1-a) continuously feeding in a longitudinal direction a single strip 20 of plastic film material for the bag body 2, the single strip 20 having opposite halves between which there is a longitudinal median line of the single strip 20;

(1-b) continuously supplying a pair of strips 30, 30 of sheet material for the framing element 10, the pair of strips 30, 30 for the framing element 10 being disposed on one surface of the unique strip 20 for the bag body in predetermined positions in respective halves of the unique strip 20;

(1-c) gluing the pair of strips 30, 30 for the frame element into the respective opposite halves of the unique strip 20 for the bag body 2;

(1-d) folding the only strip 20 for the bag body 2 and the paired strips 30, 30 for the frame member 10 in half along the longitudinal centerline of the only strip 20 for the bag body 2 so as to bring one opposite half of the only strip 20 for the bag body 2 close to the other half, thereby preparing a folded composite strip such that the paired strips 30, 30 for the frame member 10 are disposed inside the folded composite strip;

(1-e) heat bonding the folded composite strip at predetermined intervals in a direction perpendicular to the longitudinal direction thereof, thereby forming heat-sealed portions 4.. 4; and

(1-f) cutting each heat-sealed portion 4.. 4 in two in a direction perpendicular to the longitudinal direction of the folded composite strip,

also comprises the following steps:

(1-g) prior to step (1-b), forming a pliable portion 11.. 11 on each of the pair of strips 30, 30 for the frame element so as to extend in a direction perpendicular to the direction in which the pair of strips 30, 30 for the frame element 10 is fed; and

(1-h) during step (1-a), a set of insert elements 5a and a set of receiving elements 5b are provided on a unique strip for the bag body in each of the respective successive zones for the packaging bag.

First, the step (1-a) is carried out to unwind a single strip 20 of plastic film material for the bag body 2, thereby continuously supplying the single strip 20 in the longitudinal direction. The single strap 20 has opposite halves between which there is a longitudinal midline of the single strap 20. The layer structure of the single strip 20 of plastic film material for the bag body 2 is the same as that of the bag body 2 of the packaging bag 1 of the present invention described above, and therefore the description thereof is omitted.

This step (1-h) is carried out by arranging a plurality of groups of insertion elements 5a and a plurality of groups of receiving elements 5b successively on longitudinally opposite side edge portions of the upper surface of the only strip 20 for the bag body 2, so that the elements 5a, 5b integral with the only strip 20 are formed by an insert injection. Between adjacent groups of insert elements 5a there is a space 15 and between adjacent groups of receiving elements 5b there is another space 15 corresponding to the above-mentioned space 15. These corresponding spaces 15, 15 are provided on the same dash-double-dot line shown in fig. 7, which is perpendicular to the feed direction of the unique strip 20 for the bag body 2. This single strip 20 will be cut into pieces along the above-mentioned line for the respective bag body 2. Each set of insert elements 5a comprises a central main portion and opposite lateral portions, which are arranged in line and spaced from each other as shown in fig. 7. The spacing 16.. 16 between the central main portion and the opposing side portions is arranged to correspond to the readily bendable portions 11.. 11, which will be described later. Each group of receiving elements 5b also comprises 3 portions similar to the group of insertion elements 5 a. The set of male elements 5a can be engaged or disengaged with the set of female elements 5 b.

This step (1-b) is carried out to unwind the pairs of strips 30, 30 for the frame element 10 from a pair of reels arranged on the left side of fig. 8 but not shown here, feeding them in succession in their longitudinal direction to be arranged in predetermined positions for the respective half on the surface of the single strip 20 of the bag body 2.

More specifically, the strips 30, 30 for the frame element 10 are unwound at different positions from each other and fed together into a predetermined area, thus running in directions parallel to each other in their longitudinal direction. Before the pair of strips 30, 30 for the frame element 10 reaches the above-mentioned predetermined region, the step (1-g) is carried out to form the flexible portions 11.. 11 on the opposite inner surfaces of the pair of strips 30, 30 for the frame element 10 so as to extend in a direction perpendicular to the feeding direction of the pair of strips 30, 30 for the frame element 10. The flexible portion 11 is divided into pairs of flexible portions 11, 11, the pairs 11, 11 of flexible portions being arranged at a predetermined distance from each other in the feeding direction for the pairs of strips 30, 30 of the frame element. Adjacent pairs of the easily bendable portions 11, 11, 11, 11 are disposed at a distance from each other smaller than the above-mentioned predetermined distance. The pair of strips 30, 30 are cut into a plurality of pieces having sets of reinforcing portions along respective centerlines between the adjacent pliable portions as described later. Each reinforcing portion includes (i) a central portion defined by a pair of pliable portions 11, 11 and (ii) opposite side portions extending from the respective pliable portion 11, 11.

The pairs of reinforcing portions are used with the individual packages 1 such that the central portions of the pairs of reinforcing portions define the opposed front and back panel portions 8a, 8b, respectively, shown in fig. 6, and the combination of the corresponding side portions of the pairs of reinforcing portions define the side panel portions 6, respectively, of the packages 1.

Fig. 9 shows a typical apparatus for carrying out the above-described steps (1-g) to form the pliable portion 11.. 11 on each of the pair of strips 30, 30 for the frame element 10. The device comprises a roller 40, which roller 40 is provided with protrusions 41 on its outer edge. The protrusion 41 extends on the roller 40 in its longitudinal direction. The central axis of the roller 40 is perpendicular to the feeding direction of the strip 30 for the frame element 10. A base plate (not shown) is disposed to face the roller 40 and extends along the roller 40 in the longitudinal direction. The distance between the base plate and the outer peripheral surface of the roller 40 is substantially equal to or less than the thickness of the strip 30 for the frame element 10. The base plate described above may be replaced with another roller without projections.

The strip 30 passes between the base plate and the roller 40 so that the protrusions 41 penetrate the strip 30, thus forming grooves that serve as the easily bendable portion 11, the easily bendable portion 11 extending in a direction perpendicular to the feeding direction of the strip 30. A set of rollers arranged at a predetermined distance from each other, i.e. the above-mentioned roller 40 and other rollers of the same construction, are used to form the above-mentioned pairs of easily bendable portions 11.. 11 on one of the pairs of strips 30, 30 of the frame element 10. Another set of rollers having the same configuration is used to form pairs of pliable portions 11.. 11 on the other of the pairs of strips 30, 30 of the frame member 10. According to these sets of rollers, pairs of easily bendable portions can be continuously formed on the paired strips 30, 30 of the frame member 10 without suspending the feeding of the strips 30, 30.

The apparatus for carrying out steps (1-g) is not limited to the above-mentioned roller type. For example, an elongated compact having longitudinal edges may be used to form the flexible portion on the strip 30 of the frame element 10. In this case, the feeding of the ribbon 30 is intermittently stopped and the press block is pressed against the ribbon 30, thereby forming a portion which is easily bent during the stop.

The pairs of strips 30, 30 for this frame element 10, on which the sections 11 that are easily bendable have been formed by carrying out step (1-g), are fed continuously during step (1-b) so as to place them in respective halves on the inner surface of the only strip 20 for the bag body 2.

This step (1-c) is carried out by heat bonding the pairs of strips 30, 30 at their respective opposite longitudinal edges into respective halves of the single strip 20 for the bag body.

Then, the step (1-d) is carried out by folding the only strip 20 for the bag body 3 in half along the longitudinal center line of the only strip 20 for the bag body 2 together with the paired strips 30, 30 for the frame element 10, thereby bringing one opposite half portion of the single strip 20 for the bag body 2 close to the other half portion, thereby preparing a folded composite strip such that the paired strips 30, 30 for the frame element 10 are disposed in the interior of the folded composite strip as shown in fig. 10. In step (1-d), the set of insertion elements 5a is mated with the set of receiving elements 5 b. Of course, this step (1-d) may be carried out simultaneously with the steps (1-a), (1-b) and (1-c).

As shown in fig. 10, the position of each strip 30, 30 relative to the folded composite strip is determined so as to maintain a distance "L1" between the lower edge 13 of the folded composite strip and the lower edge of each strip 30, 30 and a distance "L2" between the upper edge 12 of each strip 30, 30 and the upper edge of the folded composite strip. The lower portion of the folded composite strip corresponding to the distance "L1" is used to form the bottom panel portion 7 of the package 1 as shown in fig. 3. The upper portion of the folded composite strip corresponding to the distance "L2" is used to form the top panel portion 9 of the package 1 as shown in fig. 6.

This step (1-e) is carried out by heat bonding the folded composite strip at predetermined intervals in a direction perpendicular to its longitudinal direction, so as to form the heat-sealed portions 4.. 4 shown in fig. 11. Such thermal bonding is performed by using a heat sealing plate in contact with the outer surface of the folded composite strip. The portion of the folded composite strip where the thermal bonding process is to be carried out corresponds to the respective midline between adjacent pairs of the pliable portions 11, 11, 11, 11 as described above.

Step (1-f) is then carried out to cut each heat-seal portion 4.. 4 in two in a direction perpendicular to the longitudinal direction of the folded composite strip, thereby continuously producing a plurality of packages 1. In each of the packing bags 1, opposite side edges of the reinforcing portions parallel to the flexible portions 11, 11 are embedded in the heat-seal portions 4, 4.

In the above-described process of the present invention, steps (1-a) to (1-h) are carried out on a production line. And these steps (1-a) - (1-h) can be carried out independently of each other on different production lines.

In the above-described method of the present invention, each of the pliable portions 11 provided by steps (1-g) forms a groove. The easily bendable portion 11 may have any other structure that allows the reinforcing portion obtained by cutting the strip 30 to be easily bent along the easily bendable portion 11. The flexible portion 11 may for example be provided in different perforated forms.

In the above method of the present invention, the step (1-h) is performed using plug-in implantation. The insert element 5a and the recessed element 5b, preformed by extrusion, can be glued to the only strip 20 for the bag body 2.

The inventive method described above comprises the steps (1-h) of providing a set of insertion elements 5a and a set of receiving elements 5b on the bag body 2. However, this step (1-h) may be omitted if desired.

A method of producing the second embodiment of the present invention for the above-described packing bag 1 will now be described below with reference to fig. 13 to 17.

Fig. 13 and 14 show a package 50 produced by the method of the second embodiment of the present invention. The package 50 differs from the package 1 shown in fig. 1-6 in that the former has a heat-sealed portion in the bottom panel. The package 50 includes a bag body 60 formed of a plastic film material and a frame member 70, the frame member 70 being attached to the bag body 60 prior to forming the bag body 60. A frame member 70 is folded into a rectangular parallelepiped along an easily foldable portion 73.. 73 thereof, so that the bag body 60 is also folded into a similar shape. After the envelope is filled with the contents, the upper portion of the envelope body 60 is folded into a flat state along the upper edge of the frame member 70, thereby forming an overlapping portion 61 a. The overlapping portion 61a is then bent toward the back panel portion, providing a pair of outwardly projecting trapezoidal portions 62a, 62 a. The pair of trapezoidal portions 62a, 62a are bent downwardly along the upper edge of the frame member 70 and are thermally bonded to the opposite side panel portions 54, 54, thus providing a finished product as shown in fig. 13. This completes the folding process of the upper portion of the package 50 that forms the top panel portion 62. Any other suitable adhesive may be used to adhere the trapezoidal sections 62a, 62a, and the sections 62a, 62a may be adhered to the opposing side panel sections 54, 54 by a suitable adhesive. The folding process described above is of course carried out after the package has been filled with contents.

Fig. 14 is a perspective view of the package 50 folded and then subjected to an additional folding process to provide a finished product, the perspective view showing the bottom of the package 50. When converting the package 50 from a generally flat folded condition to an expanded condition, the lower portion of the package 50 projects downwardly from the lower edge 72 of the frame member 70. The lower portion having the bottom heat-seal portion 57 formed on the lowermost edge so as to extend in the width direction of the packing bag 50 is folded into a flat state along the lower edge 72 of the frame member 70 to provide a pair of outwardly extending triangular portions 63a, 63 a. The triangular portions 63a, 63a include respective opposite side portions of the bottom heat seal portion 57 as described above, and the triangular portions 63a, 63a are bent inwardly along the lower edge 72 of the frame member 70 and are heat bonded to the corresponding portions as shown in solid lines in fig. 14 to form the bottom panel portion 63 of the package 50. Any other form of bonding may be used to bond the triangular portions 7a, 7a, and the triangular portions 7a, 7a may be bonded to the respective portions by a suitable adhesive. This completes the process of forming the lower portion of the folded package 50 of the bottom panel portion 63.

The method of the present invention for producing the second embodiment of the above-described packing bag 50 will now be described below with reference to fig. 15 to 17.

In the second embodiment of the method of the present invention, the pair of strips 80, 80 for the bag body 60 and the pair of strips 30, 30 for the frame member 10 are used to produce a plurality of packing bags 50.

More specifically, the method of producing the package 50 includes the following basic steps:

(2-a) continuously supplying a pair of strips 80, 80 of plastic film for the bag body 60 in the longitudinal direction so that they are spaced apart from each other;

(2-b) continuously feeding a pair of strips 90, 90 of sheet material for the frame element 70 such that the pair of strips 90, 90 for the frame element 70 are placed in predetermined positions on the respective inner surfaces of the pair of strips 80, 80 for the bag body 60;

(2-c) bonding the pair of strips 90, 90 for the frame member 70 to the pair of strips 80, 80 for the bag body 60, respectively;

(2-d) approaching one of the paired strips 80, 80 for the bag body 60 with the other so that the paired strips 80, 80 for the frame member 70 are opposed to each other, thus preparing a set of composite strips;

(2-e) thermally bonding the set of composite strips at predetermined intervals in a direction perpendicular to the longitudinal direction thereof, thereby forming side heat seal portions 56.. 56;

(2-f) heat sealing the composite strip set to the longitudinal edges of the composite strip set, thereby forming heat-sealed portions 57; and

(2-g) cutting each side heat seal portion 56.. 56 in two in a direction perpendicular to the longitudinal direction of the composite strip set,

also comprises the following steps:

(2-i) before the step (2-b), forming a flexible portion on each of the pair of strips 90, 90 for the frame member 70 such that it extends in a direction perpendicular to the feeding direction of the pair of strips 90, 90 for the frame member 70; and

(2-j) during step (2-a), a set of insert elements (not shown) and a set of receiving elements (not shown) are provided on the pair of strips 80, 80 for the bag body 60 in each of the respective continuous zones for the package.

First, this step (2-a) is performed to unwind the paired strips 80, 80 for the bag main body 60 from the wound strips 81, thereby continuously feeding them in the longitudinal direction so that they are spaced apart from each other. The strips 80, 80 pass between a pair of nip rollers 101, 101 so as to be in contact with each other, as shown in figure 15. The layer structure of each of the strips 80, 80 for the bag main body 60 is the same as that of the bag main body 2 of the packing bag 1 of the present invention described above, and thus the description thereof will be omitted.

Step (2-j) is carried out to provide a set of insertion elements (not shown) and a set of receiving elements (not shown) in succession on the pair of strips 80, 80 for the bag body 60 in each of the respective successive zones for the bag. This step (2-j) is carried out upstream of the above-mentioned pressing rollers 101, 101 with respect to the feeding direction of the strips 80, 80 for the bag body 60. Step (2-j) is similar to the above-described step of the first embodiment of the method of the present invention, and thus the description of step (2-j) is omitted.

This step (2-b) is carried out to unwind the paired strips 90, 90 for the frame element 70 from the wound strips 91, placing them between the paired strips 80, 80 for the bag body 60, so that the paired strips 90, 90 for the frame element 70 are located in predetermined positions on the respective inner surfaces of the paired strips 80, 80 for the bag body 60. The paired strips 90, 90 for the frame member 70 are thus passed between the above-mentioned press rollers 101, 101 together with the paired strips 80, 80 for the bag body 60, so that the step (2-d) of bringing one of the paired strips 80, 80 for the bag body 60 close to the other to cause the paired strips 80, 80 for the frame member 70 to face each other is carried out, thus preparing a set of composite strips. The pair of strips 90, 90 for the frame member 70 is guided by a pair of guide rollers 100, 100 as shown in fig. 15. The layer structure of each of the strips 90, 90 for the frame member 70 is the same as that of the frame member 10 of the envelope 1 of the present invention described above, and thus the description thereof will be omitted.

As shown in fig. 16, the position of each strip for the bag body 60 is determined so as to maintain a distance "L4" between the lower edge of the strip 80, 80 for the bag body 60 and the lower edge of each strip 90, 90 and a distance "L3" between the upper edge of each strip 90, 90 and the upper edge of the strip 80, 80 for the bag body 60. The lower portion of the strips 80, 80 for the bag body 60, corresponding to the distance "L4", is used to form the bottom panel portion 55 of the package 50 shown in fig. 14. The upper portions of the strips 80, 80 for the bag body 60 corresponding to the distance "L3" are used to form the top panel portion 53 of the package 50 shown in fig. 13.

Before the pair of strips 90, 90 for the frame member 70 reaches the above-mentioned guide rollers 100, step (2-i) is carried out so as to form the readily bendable portions 73.. 73 on the opposite inner surfaces of the pair of strips 90, 90 for the frame member 70 so as to extend in the direction perpendicular to the feeding direction of the pair of strips 90, 90 for the frame member 70. Step (2-i) is similar to step (1-g) described above for the first embodiment of the method of the present invention, and thus the description of step (2-i) is omitted.

Step (2-c) is carried out to thermally bond the pair of strips 90, 90 for the frame member 70 to the pair of strips 80, 80 for the bag main body 60, respectively, at the opposite longitudinal edges thereof. Step (2-c) is used on the downstream side of the press rolls 101, 101 with respect to the direction of feed of the strips 80, 80 for the bag body 60.

In addition, step (2-c) is carried out to thermally bond the combination of the paired strips 80, 80 for the bag main body 60 and the paired strips 90, 90 for the frame member 70, i.e., the set of composite strips, at predetermined intervals in a direction perpendicular to the longitudinal direction thereof so as to form the side heat-seal portions 56.. 56.

Step (2-f) is performed to thermally bond the set of composite strips on the lower longitudinal edges thereof to form a bottom heat-sealed portion 57.

Step (2-g) is then carried out to cut each side heat-seal portion 56.. 56 in two in a direction perpendicular to the longitudinal direction of the set of composite strips, thereby continuously producing a plurality of packaging bags 50. In each of the packing bags 50, opposite side edges of the reinforcing portion of the frame member 70 parallel to the readily bendable portions 73, 73 are embedded in the side heat-seal portions 56, as shown in fig. 17.

In the above-mentioned method of the present invention, steps (2-a) to (2-j) are carried out in production. Steps (2-a) - (2-j) can be carried out independently of each other on different production lines.

In the above-described second embodiment of the method of the present invention, the modification step (2-i) may be performed as in the step (1-g) in the method of the first embodiment of the present invention.

In the above-described second embodiment of the method of the present invention, the modification step (2-j) may be performed as in the step (1-h) in the method of the first embodiment of the present invention.

The above-described second embodiment of the method of the invention comprises the step (2-j) of providing the set of insertion elements 5a and the set of receiving elements 5b on the pair of strips 80, 80 for the bag body 60. This step (2-j) may be omitted if desired.

In the above-described second embodiment of the method of the present invention, the width of the pair of strips 80, 80 for the bag body 60 is approximately the same as the height of the package 50. Thus, each successive step (2-g), i.e., a unique cutting operation, provides a unique package 50. However, a modification may be adopted in which, on the one hand, the width of each pair of strips 80, 80 for the bag bodies 60 is increased so that a plurality of bag bodies 60 can be distributed in an area of the strip 80, the area of the strip 80 extending over the entire width of the strip 80, and, on the other hand, a plurality of pairs of strips 90, 90 for the frame element 70 are supplied.

A description will now be given of such a modified embodiment in which 3 bag bodies are dispensed in a region of the strip 80, the region of the strip 80 extending along the entire width of the strip 80, with reference to fig. 18, 19.

Fig. 18 is a simplified diagram illustrating a modification of the method of the present invention in which a group of 3 packages may be disposed in a region of the group of composite strips, the region of the group of composite strips 80 extending in a direction perpendicular to the direction of feed of the group of composite strips. The horizontal direction in fig. 18 corresponds to the width direction, i.e., the direction perpendicular to the feeding direction of the pair of strips 110, 110 for the bag main body.

The width of each of the pair of strips 110, 110 for the bag body is 3 times the width of the packaging bag 50 to be produced. These strips 110, 110 are fed in their longitudinal direction so as to be spaced from each other in the same way as step (2-a) of the above-described second embodiment of the method of the invention.

The 3 pairs of strips 120, 120 for the frame element are also fed in their longitudinal direction to be arranged between the above-mentioned pairs of strips 110, 110 for the bag body in the same way as step (2-b) of the above-mentioned second embodiment of the method of the invention. The 3 pairs of strips 120, 120 are spaced apart from each other by a predetermined distance in the width direction of the strips 110, 110 for the pouch body.

The opposite longitudinal edge portions 121, 122 of the respective strip 120 are thermally bonded to the respective strip 110 for the bag body, and then the pairs of strips 110, 110 for the bag body are brought close one to the other, resulting in one to the other of each pair of strips 120, 120 for the frame element, so as to prepare a set of composite strips in the same manner as in the steps (2-c), (2-d) of the above-described second embodiment of the invention, as shown in the first region between the two dot-dash lines "a 1" and "a 2" in fig. 19.

Then, the group of composite strips was thermally bonded at 3 positions in the longitudinal direction, i.e., the lowermost position of the group of composite strips as shown in fig. 19 and additional two positions which divide the group of composite strips into 3 equal parts in the width direction (i.e., the vertical direction in fig. 19), thereby forming 3 bottom heat-sealed portions 111, 111, 111 in the same manner as in the above-described step (2-f) of the second embodiment of the method of the present invention, as shown in the second region between the two-dot chain lines "a 2" and "A3" in fig. 19.

In addition, the set of composite strips is thermally bonded at predetermined intervals in a direction perpendicular to the longitudinal direction thereof, thereby forming side heat-sealed portions 112.. 112 in the same manner as in the above-described steps (2-e) of the method of the present invention in the above-described embodiment, as shown by the third region between the two-dot chain lines "A3" and "a 4" in fig. 19. Each of the side heat seal portions 112 so formed extends across the set of composite strips in a width direction thereof. The area defined by the bottom heat seal portions 111, 111, 111 and the side heat seal portions 112.. 112 will form a corresponding package.

Then, the thus heat-sealed set of composite strips was cut into 3 semi-finished strips for the packaging bag at two locations in the longitudinal direction, as shown by the fourth region between the two-dot chain lines "a 4" and "a 5" in fig. 19. These two locations are directly below the two additional locations for thermal bonding described above that divide the set of composite strips into 3 equal sections in the width direction as shown in fig. 19. The 3 semi-finished strips obtained for this bag are therefore approximately of the same width. Each of the semi-finished strips for the packages thus prepared is formed into a series of packages. The second embodiment of the present invention described above does not include such a cutting step.

Each of the semi-finished strips for the packages is then subjected to a further cutting step to cut each of the side heat-seal portions 112.. 112 in two in a direction perpendicular to the longitudinal direction of the semi-finished strip, thereby producing a plurality of individual packages.

The above-described method of the present invention can significantly improve the production efficiency.

The above-described method and improvements of the present invention provide for the continuous production of a plurality of packages. The method of the present invention can be operated in a mass production system as follows.

A method of the present invention in a third embodiment for producing the above-described packing bag will now be described with reference to fig. 20.

In a third embodiment of the invention, a single sheet for the bag body and a pair of sheets 140, 140 for the frame member are used to produce a single package.

More specifically, the method for producing the packaging bag comprises the following main steps:

(3-a) preparing a single sheet of plastic film material for the bag body, the single sheet having opposed halves 131, 131 with the single sheet midline 130b therebetween;

(3-b) placing a pair of sheets of thin sheet material 140, 140 for a frame member in predetermined positions for the respective opposed halves 131, 131 of a single sheet of the bag body on a surface of the single sheet;

(3-c) bonding the pair of sheets 140, 140 for the frame member to the single sheet for the bag body in the respective opposite half positions 131, 131 thereof;

(3-d) folding the single sheet for the bag body in half along the midline 130b together with the pair of sheets for the frame member so that one opposing half 131, 131 of the single sheet for the bag body is adjacent to the other opposing half 131, 131 to prepare a folded composite sheet such that the pair of sheets 140, 140 for the frame member are disposed inside the folded composite sheet; and

(3-e) heat bonding the folded composite sheet on opposite sides thereof to form heat-sealed portions,

the following optional steps are also included:

(3-f) forming an easy-to-fold portion on each of the pair of sheets for the frame member before the step (b); and

(3-g) a set of insertion members (not shown) and a set of receiving members (not shown) are provided in each of the opposite longitudinal sides of the single sheet for the bag body so as to extend in the width direction thereof.

First, step (3-a) is performed to prepare a single sheet of plastic film material for the bag body. Such a sheet for the bag body forms a rectangular shape having a long side having a length "M" and a short side having a length "N". Fig. 20 shows a sheet for the bag body, the sheet being folded in half so that fig. 20 includes an indication of "M/2". The sheet for the bag body has opposite halves 131, 131, between which halves 131, 131 a median line 130b of the single sheet is present. The layer structure of the sheet for the bag main body 60 is the same as that of the bag main body of the packing bag 1 of the present invention described above, and therefore, the description thereof will be omitted.

Step (3-g) is carried out to provide a set of insertion members (not shown) and a set of receiving members (not shown) on respective half portions of the sheet for the bag main body so as to extend in the width direction on opposite portions of the long side edges of the sheet for the bag main body. Step (3-g) is similar to step (1-h) above of the first embodiment of the method of the present invention.

Pairs of sheets 140, 140 for the frame members are prepared. The width of each sheet 140, 140 is less than the width of the sheet for the pouch body, i.e., the short side edges, by a width "N1" of the portion of the sheet for the pouch body to be heat bonded, which is twice the length "N", as shown in fig. 20. The layer structure of each sheet 140, 140 for the frame member is the same as that of the frame member of the packing bag 1 of the present invention described above, and thus the description thereof will be omitted.

The thus prepared sheet 140, 140 for a frame member is subjected to step (3-f) before step (3-b) described later, so that a pair of easily bendable portions 141 are formed on each of the pair of sheets for a frame member in the same manner as in step (1-g) of the above-described first embodiment of the method of the present invention. Each sheet 140, 140 has a first pair of opposing side edges (i.e., right and left side edges) and a second pair of opposing side edges (i.e., upper and lower side edges) 142, 143. The flexible portions 141 extend parallel to the left and right side edges of the sheet 140 of the frame member as shown in fig. 20.

Then, step (3-b) is carried out for placing pairs of sheets of sheet material for the frame element on the surface of a single sheet for the bag body in predetermined positions of the respective opposite halves 131, 131. The sheet 140 is disposed in a predetermined position on half 131 such that a distance "M1" between the upper edge 142 of the sheet 140 and one of the opposing short side edges of the single sheet for the bag body is maintained, and a distance "M2" between the lower edge of the sheet 140 and the midline 130b of the single sheet. The determination of the position of the sheet 140 relative to the half of the single sheet for the bag body is also made on the other half 131.

Then, step (3-c) is performed for thermally bonding the pair of sheets 140, 140 for the frame element into the corresponding opposite halves 131, 131 of the single sheet for the bag body. These sheets 140, 140 are thermally bonded at their outer edges into the corresponding halves 131, 131 of the single sheet for the bag body as shown in phantom in fig. 20.

Step (3-d) is then carried out to fold the single sheet for the bag body in half along the midline 130b of the single sheet for the bag body together with the pair of sheets for the frame member, thereby bringing one of the opposite halves of the single sheet for the bag body close to the other to prepare a folded composite sheet such that the pair of sheets 140, 140 for the frame member is disposed inside the folded composite sheet.

Step (3-e) is then carried out to thermally bond the folded composite sheet to its opposite side edges, i.e., portions 132, to form a heat-sealed portion having a width "N1" to produce the package. The thus produced packaging bag includes a bag body composed of a single sheet and a pair of reinforcing portions composed of a pair of sheets 140, 140. The right and left side edges (i.e., the first pair of opposite side edges) and the upper and lower side edges (i.e., the second pair of opposite side edges) of the reinforcing part 140 are thermally bonded to the other regions of the bag main body except the pair of side heat-seal parts.

The package can be converted to an expanded state and subjected to a post-bending processing step to provide a finished product in the form of a rectangular parallelepiped in the same manner as the package described and illustrated in fig. 1-6.

The method of the fourth embodiment of the invention for producing the transfer bag is now described below with reference to figure 21.

In a fourth embodiment of the method of the present invention, the pair of sheets 150, 150 for the bag body and the pair of sheets 160, 160 for the frame member are used to produce a single package.

(4-a) disposing a pair of sheets 150, 150 of plastic film material for the bag body so that they are separated from each other;

(4-b) disposing a pair of sheets 160, 160 of sheet material for the frame element in predetermined positions of respective inner surfaces of the pair of sheets 150, 150 for the bag body;

(4-c) bonding the pair of sheets 160, 160 for the frame member to the pair of sheets 150, 150 for the bag body, respectively;

(4-d) bringing one of the pair of sheets 150, 150 for the bag body close to the other so that the pair of sheets 160, 160 for the frame member face each other, thus preparing a set of composite sheets; and

(4-e) thermally bonding the plurality of composite sheets at opposite side edges and bottom edges thereof to form side heat-seal portions and bottom heat-seal portions;

also includes the following optional steps:

(4-f) forming an easy-to-fold portion on each of the pair of sheets for the frame member before the step (b); and

(4-g) a set of insertion members (not shown) and a set of receiving members (not shown) are provided in each of the pair of sheets 150, 150 for a bag main body so as to extend in their width direction.

First, step (4-a) is carried out to arrange the pair of plastic film material sheets 150, 150 for the bag body so that they are separated from each other. Each of the sheets 150, 150 for the bag body has the same rectangular shape. The layer structure of the sheets 150, 150 for the bag main body is the same as that of the bag main body 2 of the packing bag 1 of the present invention described above, and thus the description thereof is omitted.

Step (4-g) is performed to provide a set of insertion members (not shown) and a set of receiving members (not shown) in each of the pair of sheets 150, 150 for the bag body so as to extend in their width direction. Steps (4-g) are similar to steps (1-h) of the above-described first embodiment of the method of the present invention, and thus the description of step (4-g) is omitted.

Pairs of sheets 160, 160 for the frame member are prepared. The width of each sheet 160, 160 is less than the width of each of the sheets 150, 150 for the bag body by twice the width "R" of the portion 151 of the sheet for the bag body to be heat bonded, as shown in fig. 21. The layer structure of each sheet 160, 160 for the frame member is the same as that of the above-described packing bag of the present invention, and thus the description thereof is omitted.

The thus prepared sheet 160, 160 for a frame member is subjected to step (4-f) before step (4-b) described later, so that a pair of easily bendable portions is formed on each of the pair of sheets 160, 160 for the frame member in the same manner as step (1-g) in the first embodiment of the method of the present invention. Each sheet 160, 160 has a first pair of opposing side edges (i.e., left and right side edges) and a second pair of opposing side edges (i.e., upper and lower side edges) 162, 163. The easily bendable portions 161 are parallel to the left and right side edges of the sheet 160 for the frame member, as shown in fig. 21.

Then, step (4-b) is carried out to set the pair of sheets 160, 160 for the frame member in predetermined positions on the respective sheets 150, 150 for the pair of bag bodies. The flap 160 is disposed in a predetermined position of the flap 150 such that a distance "P1" between the upper edge 162 of the flap 160 and one of the opposing short side edges of the flap 150 for the bag body and a distance "P2" between the lower edge of the flap 160 and the other of the opposing short side edges of the flap 150 for the bag body are maintained. The determination of the position of the sheet 160 is also made relative to another sheet for the bag body.

Step (4-c) is then performed to thermally bond the pair of sheets 160, 160 for the frame member to the pair of sheets 150, 150 for the bag body, respectively. These sheets 160, 160 are heat bonded at their outer edges to the respective sheets 150, 150 for the bag body as shown in fig. 21.

Then, the step (4-d) is carried out to bring the pair of sheets 150, 150 for the bag body close to each other so that the pair of sheets 160, 160 for the frame member face each other, thus preparing a set of composite sheets.

Then, the step (4-e) is performed to thermally bond the plurality of composite sheets at the opposite side edges 151, 151 and the bottom edge 151 thereof to form the side heat-sealed portions and the bottom heat-sealed portion, thereby producing the packing bag. The thus produced packaging bag includes a bag body constituted by the pair of sheets 150, 150 and a pair of reinforcing portions constituted by the pair of sheets 160, 160. The left and right side edges (i.e., a first pair of opposite side edges) and the upper and lower side edges (i.e., a second pair of opposite side edges) of the reinforcing part 160 are thermally bonded to the bag body at other regions than the pair of side heat-seal parts.

The package is converted to an expanded state and subjected to a post-bending processing step to provide a finished product in the form of a rectangular parallelepiped identical to the package shown and described in fig. 1-6.

A method of a fifth embodiment of the present invention for producing the packing bag will be described below with reference to fig. 22.

In the fifth embodiment of the present invention, the pair of sheets 180, 180 for the bag body and the frame member 170 forming the liner are used to produce a single packing bag.

(5-a) disposing a pair of sheets 180, 180 of plastic film material for the bag body so that they are separated from each other;

(5-b) disposing the frame member 170 for forming a liner in the respective predetermined positions of the pair of sheets 180, 180 for the bag body;

(5-c) bonding the frame member 170 to the pair of sheets 180, 180 for the bag body;

(5-d) bringing one of the pair of sheets 180, 180 for a bag body close to the other so that the frame 170 is accommodated between the pair of sheets 160, 160 for a bag body, thus preparing a set of composite sheets; and

(5-e) heat bonding the plurality of composite sheets at opposite side edges and bottom edges thereof to form side heat seal portions and a bottom heat seal portion;

also includes the following optional steps:

(5-f) forming an easily foldable portion on the frame member before the step (b); and

(5-g) a set of insertion members (not shown) and a set of receiving members (not shown) are provided in each of the pair of sheets 150, 150 for a bag main body so as to extend in their width direction.

First, step (5-a) is carried out to arrange the pair of plastic film material sheets 180, 180 for the bag body so that they are separated from each other. Each of the sheets 180, 180 for the bag body has the same rectangular shape. The layer structure of the sheets 180, 180 for the bag main body is the same as that of the bag main body 2 of the packing bag 1 of the present invention described above, and thus the description thereof is omitted.

Step (5-g) is performed to provide a set of insertion members (not shown) and a set of receiving members (not shown) in each of the pair of sheets 180, 180 for the bag body so as to extend in their width direction. Steps (5-g) are similar to steps (1-h) of the above-described first embodiment of the method of the present invention, and thus the description of step (5-g) is omitted.

A frame member 170 in the form of a bushing is prepared, and the frame member 170 has openings on the upper and lower sides thereof. The frame element 170, which is constituted by a sheet of plastic material, comprises a pair of opposite reinforcing portions, each having the same rectangular shape. The opposed reinforcing portions are combined by a pair of flexible portions 172, 172, wherein the pair of flexible portions 172, 172 extend in the direction of the opening of the bushing, i.e., the frame member 170. Each of the opposing reinforcing portions further has another pair of easily bendable portions 171, 171 extending parallel to the pair of easily bendable portions 172, 172 at a predetermined distance in the inwardly shifted position, the six easily bendable portions being the pair of easily bendable portions 172, 172 mentioned above, the first pair of easily bendable portions disposed in one of the opposing reinforcing portions and the second pair of easily bendable portions 171, 171 disposed in the other of the opposing reinforcing portions allowing the frame member 170 to be converted between a generally flat collapsed state and an expanded state. The width of the frame member 170 in the generally flat folded condition is less than the width of each of the sheets 180, 180 for the bag main body by twice the width of a side edge portion 181, wherein the side edge portion 181 is the portion of the sheet 180 for the bag main body to be heat bonded as shown in fig. 22. The layer structure of the plastic material for the frame member is the same as that of the frame member 10 of the packing bag of the present invention described above, and thus the description thereof will be omitted.

The above-mentioned frame member 10 is obtained by the step (4-f) of forming the easily bendable portions 171, 171, 171, 172, 172 on the extension sheet of plastic material for the frame member 170, and then further additional steps of bringing one edge of the above-mentioned sheet for the frame member 170 close to the other edge thereof and combining the edges with each other are carried out. Step (5-f) is carried out in the same manner as step (1-g) in the first example of the method of the present invention. The connection portion connecting the opposite edges of each sheet for the frame member 170 to each other may be designed to serve as one of the easily bendable portions 171, 171, 171, 171, 172, 172.

Step (5-b) is then carried out for disposing the frame members 170 in a generally flat folded condition in predetermined positions on the respective sheets 180, 180 for the pair of bag bodies. The frame member 170 is disposed in a predetermined position of the sheet 180 such that a distance "S1" between the upper edge 173 of the frame member 170 and one of the opposed short side edges of the sheet 150 for the bag body is maintained and a distance "S2" between the lower edge of the frame member 170 and the other of the opposed short side edges of the sheet 150 for the bag body is maintained. The determination of the position of the sheet 170 is also made relative to another sheet for the bag body.

Step (5-c) is then performed to thermally bond the frame member 170 to the pair of sheets 180, 180 for the bag body, respectively. The frame member 170 is heat bonded at its outer edges to respective tabs 180, 180 for the bag body as shown in fig. 22.

Then, the step (5-d) is carried out to bring one of the pair of sheets 180, 180 for a bag body close to the other so that the frame member 170 is accommodated between the pair of sheets 180, 180 for a bag body, thus preparing a set of composite sheets.

Then, the step (5-e) is performed to thermally bond the plurality of composite sheets at the opposite side edges 181, 181 and the bottom edge 181 thereof to form the side heat-sealed portions and the bottom heat-sealed portion, thereby producing the packing bag. The package thus produced comprises a package body formed of pairs of sheets 180, 180 and a frame member 170, i.e. a sleeve. Portions 181, 181 of the sheets 180, 180 are thermally bonded to form opposing side heat seal portions adjacent which the pairs of pliable portions 172, 172 of the frame member 170 are disposed.

According to the present invention as described above, the packing bag includes the bag main body and the frame member which is attached to the bag main body before the bag main body forming step is completed, some problems can be avoided when the liner is inserted into the bag main body according to the related art, so that the packing bag is easily produced, and thus the production cost is reduced. It is also possible to provide a superior appearance in the expanded state.

According to the method of the present invention, the above-described packaging bag can be efficiently produced.

The entire disclosure of japanese patent application 2002-343845, filed 11/27/2002, including the specification, claims and drawings as well as abstract, is hereby incorporated by reference in its entirety.

Claims

1. A method for producing a packaging bag, comprising the steps of:

a continuously feeding a pair of strips of thermoplastic film material for a bag body in a longitudinal direction so that they are spaced from each other;

b continuously feeding a pair of strips of sheet material for a framing element to place said pair of strips for the framing element in predetermined positions on respective inner surfaces of said pair of strips for said bag body;

c bonding said pair of strips for the frame element to said pair of strips for the bag body, respectively;

d approaching one of said pair of strips for the bag body with the other of said pair of strips for the bag body, thereby causing said pair of strips for the frame element to oppose each other, thus preparing a set of composite strips;

e heat-bonding the composite strip group at predetermined intervals in a direction perpendicular to the longitudinal direction thereof to form side heat-sealed portions;

f heat bonding said composite strip set at one longitudinal edge thereof to form a bottom heat seal; and

g cutting said heat-sealed portions into two in a direction perpendicular to the longitudinal direction of said composite strip set,

thereby continuously producing a plurality of packing bags each comprising the bag main body and the frame member foldable/unfoldable with said bag main body so as to shift said frame member and said bag main body between a substantially flat folded state and an expanded state.

2. The method of claim 1, further comprising the steps of:

h forming a flexible portion on either of said pair of strips for the frame element, before said step b, so that they extend in a direction perpendicular to the feeding direction of said pair of strips for the frame element.

3. The method of claim 1, wherein

The steps a-g are carried out on a production line.

4. The method of claim 2, wherein:

the steps a-h are carried out on a production line.