JP7597997B2 - Packaging Bag - Google Patents

Description

The present invention relates to a packaging bag suitable for heating the contents in a microwave oven.

Patent Document 1 discloses a packaging bag in which a flexible film is welded at a seal. This packaging bag is provided with a steam release seal to allow the escape of steam generated when the contents are heated in a microwave oven.

WO2013/100058

In Patent Document 1, a steam release seal is formed by providing a seal part at the gable part that is curved in a roughly V-shape and protrudes toward the inside of the packaging bag, but in a device that continuously produces bags and fills them with the contents (a bag production and filling device), it is not easy to form a steam release seal part with this configuration.

The present invention was made in consideration of these circumstances, and provides a packaging bag that can easily form a steam release seal portion during the bag making and filling process without using a special bag making and filling device.

According to the present invention, a packaging bag is provided in which a film is welded at a seal portion, the seal portion has a steam release seal portion that forms a steam flow path as the internal pressure increases, the film has a modified area in which the surface of the film has been corona discharge treated, and the steam release seal portion is a portion in which the modified area and its opposing surface are welded.

In the packaging bag of the present invention, the steam release seal portion is formed by taking advantage of the fact that the seal strength at high temperatures decreases in the modified area that has been corona discharge treated, so the steam release seal portion can be easily formed during the bag filling process without using special bag filling equipment.

Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other.
Preferably, in the packaging bag described above, the sealed portion comprises an upper horizontal seal portion arranged to close the upper side of the packaging bag, and a lower horizontal seal portion arranged to close the lower side of the packaging bag, and the modified region is arranged in a stripe shape across the upper horizontal seal portion, the lower horizontal seal portion, and the non-sealed portion between them.
Preferably, in the packaging bag described above, the film is a laminated film in which a base film and a sealant film are laminated, the sealant film has a laminate surface on the base film side and a seal surface opposite the laminate surface, the modified area is a seal surface modified area in which the seal surface has been corona discharge treated, and the laminate surface is provided with a laminate surface modified area in which the laminate surface has been corona discharge treated.
Preferably, in the packaging bag described above, the laminate surface modified region has an area larger than that of the sealing surface modified region.
Preferably, the method for manufacturing the packaging bag described above includes a corona discharge treatment step, in which corona discharge treatment is performed so that the surface energy of the sealing surface modified area is greater than the surface energy of the laminate surface modified area.
Preferably, the method for manufacturing the packaging bag described above includes a corona discharge treatment step, in which a corona discharge treatment is performed on the laminate surface to form the laminate surface modified area, and then a corona discharge treatment is performed on the seal surface to form the seal surface modified area.

FIG. 1 is a front view of a packaging bag 1 according to one embodiment of the present invention (for convenience, the bag is shown in a state where no contents are filled). FIG. 2A is an exploded view showing the layer structure of a film 2 used in manufacturing a packaging bag 1, and FIG. 2B shows the film 2 as viewed from a sealing surface 2d. FIG. 2 is a block diagram showing a manufacturing process of a corona discharge treated sealant film 12. FIG. 1 is a configuration diagram of a bag making and filling machine 100. 5 is an enlarged view of the vicinity of a transverse sealer 116 of the bag making and filling machine 100 of FIG. 4, showing a state in which a transverse seal portion 32 is being formed by the transverse sealer 116. FIG. 5, the horizontal sealing machine 116 is opened and the horizontal sealing unit 32 moves to the position of the press/cutter 118. 6 shows the state in which the horizontal seal portion 32 is being clamped by the press/cutter 118. 8 shows a state after the press/cutter 118 and the squeezing rollers 115 are opened from the state shown in FIG. 8, shows a state after the contents W are further added and the squeezing rollers 115 are closed. 10 shows a state after the sealed portion 5a has moved from the state shown in FIG. 9 to the position of the horizontal sealer 116.

The following describes the embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. In addition, each feature can be an invention independently.

1. Packaging bag 1
1 and 2, a packaging bag 1 according to one embodiment of the present invention is configured by welding a film 2 at a seal portion 3. The seal portion 3 includes a steam release seal portion 4 that forms a steam flow path as the internal pressure of the packaging bag 1 increases.

Packaging bag 1 is intended for heating the contents within packaging bag 1 in a microwave oven, and as the contents are heated, the moisture contained in the contents turns to steam, causing the internal pressure of packaging bag 1 to rise. Because steam release seal section 4 has a weaker seal strength than the other parts of seal section 3, when the internal pressure of packaging bag 1 rises, the seal at steam release seal section 4 is broken and a steam flow path is formed. Steam is released to the outside from this steam flow path, preventing damage to packaging bag 1 due to an excessive increase in internal pressure.

The seal section 3 includes a vertical seal section 31 and a horizontal seal section 32. The vertical seal section 31 is formed by bending the film 2 into a cylindrical shape and welding the film 2 at the overlapping section where both side edge sections of the film 2 are overlapped. In this embodiment, the vertical seal section 31 is of a palm-to-palm type in which the inner faces of the film 2 are welded together. The cylinder 5 is formed by forming the vertical seal section 31 in the film 2.

The horizontal seal portion 32 includes an upper horizontal seal portion 32a and a lower horizontal seal portion 32b. The upper horizontal seal portion 32a and the lower horizontal seal portion 32b are provided to close the upper and lower sides of the cylindrical body 5, respectively. The horizontal seal portions 32a, 32b are preferably formed along the upper and lower ends of the cylindrical body 5, respectively. The horizontal seal portions 32a, 32b are preferably formed so as to be perpendicular to the vertical seal portion 31. The horizontal seal portions 32a, 32b can each be formed by heat sealing the cylindrical body 5.

As shown in FIG. 2, the film 2 has a modified region 7 in which the surface of the film 2 has been corona discharge treated. The modified region 7 is provided on the sealing surface (surface to be welded) 2d of the film 2. The modified region 7 is formed so that a part or the whole of the modified region 7 overlaps with the area in which the seal portion 3 is formed. In the modified region 7, polar groups such as hydroxyl groups and carbonyl groups are formed by the corona discharge treatment. The area where the modified region 7 and its opposing surface are welded has low seal strength at high temperatures, so this area becomes the steam release seal portion 4. The opposing surface may or may not be corona discharge treated.

As shown in FIG. 1, the value of [left-right width W1 of steam release seal portion 4/left-right width W2 of horizontal seal portions 32a, 32b] is, for example, 0.05 to 0.8, and preferably 0.1 to 0.3. If this value is too small, steam may not escape properly, and if this value is too large, steam may escape too quickly, resulting in insufficient heating of the contents. Specific examples of this value are 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8, and may be within a range between any two of the values exemplified here.

The modified region 7 is provided in a stripe shape across the upper horizontal seal section 32a, the lower horizontal seal section 32b, and the non-sealed section 8 between them. In this case, the steam release seal section 4 is provided in each of the horizontal seal sections 32a, 32b, making it easy to release steam smoothly. In addition, the modified region 7 provided in the non-sealed section 8 has good surface wettability, so the film 2 is less likely to fog up in the modified region 7 of the non-sealed section 8, and the visibility of the contents is excellent. Furthermore, such stripe-shaped modified regions 7 can be easily formed by continuously performing a corona discharge treatment on the film moving in the longitudinal direction.

As shown in FIG. 2A, the film 2 is preferably a laminated film having a base layer 2a and a sealant layer 2b, and more preferably has an adhesive layer 2c between the base layer 2a and the sealant layer 2b.

The base layer 2a is arranged so as to be exposed on the outer surface of the packaging bag 1, and the sealant layer 2b is arranged so as to be exposed on the inner surface of the packaging bag 1. The sealant layers 2b are heat sealed together to form the vertical seal portion 31 and the horizontal seal portions 32a and 32b.

The base layer 2a is made of a material that has excellent strength and high impact resistance. For example, polyamide is used as the base layer 2a. The adhesive layer 2c is a layer for bonding the base layer 2a and the sealant layer 2b so that they are laminated together, and for example, polyethylene is used as the adhesive layer 2c.

The polyamide of the base layer 2a preferably contains an aromatic polyamide. This is because the barrier properties of the base layer 2a are excellent in this case. There are no particular limitations on the aromatic polyamide, but resins containing 70 mol % or more of polyamide structural units consisting of xylylenediamine and α,ω aliphatic dicarboxylic acid having 6 to 12 carbon atoms in the molecular chain can be used. Specific examples include homopolymers such as polymetaxylylene adipamide, polymetaxylylene pimelamide, polymetaxylylene azelamide, polyparaxylylene azelamide, and polyparaxylylene decanamide, and copolymers such as metaxylylene/paraxylylene adipamide copolymer, metaxylylene/paraxylylene pimelamide copolymer, metaxylylene/paraxylylene azelamide copolymer, and metaxylylene/paraxylylene sepacamide copolymer. Of these, polymetaxylylene adipamide (hereinafter referred to as "MXD6") is preferred because it has excellent basic properties such as strength and gas barrier properties, and is relatively easy to obtain industrially.

The sealant layer 2b can be made of a resin with excellent heat sealability. For example, the sealant layer 2b can be made of polyethylene (e.g., linear low-density polyethylene).

The film 2 can be formed by laminating a base layer 2a having a thickness of 10 μm to 20 μm, for example 15 μm, an adhesive layer 2c having a thickness of 10 μm to 30 μm, for example 20 μm, and a sealant layer 2b having a thickness of 30 μm to 50 μm, for example 40 μm, and the film 2 usually has a thickness of 50 μm to 100 μm.

The film 2 is preferably a laminated film in which a base film 11 constituting the base layer 2a and a sealant film 12 constituting the sealant layer 2b are laminated. The base film 11 and the sealant film 12 are preferably bonded to each other via the adhesive layer 2c using an extrusion lamination method. The base film 11 and the sealant film 12 may be heat-sealed without the adhesive layer 2c.

The corona discharge treatment for forming the modified region 7 may be performed after the laminate film is formed, or the laminate film may be formed using the corona discharge treated sealant film 12.

The surface of the sealant film 12 facing the base film 11 is referred to as the lamination surface 12a, and the surface opposite the lamination surface 12a is referred to as the sealing surface 12b. The sealing surface 12b becomes the sealing surface 2d of the film 2.

The corona discharge treated sealant film 12 preferably has a laminate surface modified region 7a where the laminate surface 12a has been corona discharge treated, and a seal surface modified region 7b where the seal surface 12b has been corona discharge treated. The seal surface modified region 7b becomes the modified region 7. By providing the laminate surface modified region 7a, the adhesion between the sealant film 12 and the base film 11 or the adhesive layer 2c is improved.

As shown in FIG. 2, the value of [left-right width W3 of sealing surface modified region 7b/left-right width W4 of sealant film 12] is, for example, 0.02 to 0.4, and preferably 0.05 to 0.2. The left-right width W3 of sealing surface modified region 7b coincides with the width W1 of steam release seal portion 4, so if this value is too small, steam may not escape properly, and if this value is too large, steam may escape too quickly, resulting in insufficient heating of the contents. Specific examples of this value are 0.02, 0.05, 0.1, 0.2, 0.3, and 0.4, and may be within a range between any two of the values exemplified here.

It is preferable that the laminate surface modified region 7a has a larger area than the sealing surface modified region 7b. The value of [area of laminate surface modified region 7a/area of sealing surface modified region 7b] is, for example, 1.1 to 30, specifically, for example, 1.1, 1.5, 2, 3, 4, 5, 10, 15, 20, 25, 30, and may be within a range between any two of the numerical values exemplified here. Preferably, the left-right width of the modified regions 7a, 7b is constant along the longitudinal direction of the sealant film 12, and in this case, the area ratio of the modified regions 7a, 7b matches the left-right width ratio of the modified regions 7a, 7b.

From the viewpoint of suppressing delamination, it is preferable that the laminate surface modified region 7a is formed over as wide an area as possible of the laminate surface 12a, and it is even more preferable that it is provided over the entire laminate surface 12a. The value of [area of laminate surface modified region 7a/area of laminate surface 12a] is, for example, 0.2 to 1, and specifically, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, and may be within a range between any two of the numerical values exemplified here.

Here, we will use Figure 3 to explain the manufacturing method of the corona discharge treated sealant film 12. This method includes a corona discharge treatment process.

First, a circular film 14 is extruded from the circular slit of the die 13 and then sandwiched between a pair of rollers 15 to flatten it into a flat film 16.

Next, a corona discharge is generated in the gap between the anode 17a and cathode 17b of the corona discharge treatment device 17, and corona discharge treatment is performed on the outer surface of the flat film 16. In this embodiment, corona discharge treatment is performed on both sides of the flat film 16 using two corona discharge treatment devices 17 with different arrangements of the anode 17a and cathode 17b. The cathode 17b is, for example, in the shape of a roller.

Next, both edges of the flat film 16 turned by the turning roller 19 are cut with a cutter (not shown) to separate the flat film 16 into two films 20, which are then bifurcated using the turning roller 21. Note that after cutting one edge of the flat film 16, the flat film 16 may be opened to form a single film.

Next, the surface of each film 20 that corresponds to the inner surface of the flat film 16 is subjected to corona discharge treatment using a corona discharge treatment device 17, and then wound into a roll to obtain a film roll 12r of the sealant film 12.

The above steps result in a sealant film 12 that has been corona discharge treated on both sides. In the above description, the corona discharge treatment is incorporated into the manufacturing process for the sealant film 12, but the corona discharge treatment step may be performed after the manufacturing of the sealant film 12 is completed. Alternatively, one side of the sealant film 12 may be subjected to corona discharge treatment before the sealant film 12 is wound into a roll, and then the other side of the sealant film 12 may be subjected to corona discharge treatment in a roll-to-roll manner. In the above description, the sealant film 12 is manufactured by the inflation method, but the sealant film 12 may also be manufactured by another method, such as the T-die method.

Whether the laminate surface corona discharge treatment to form the laminate surface modified region 7a or the seal surface corona discharge treatment to form the seal surface modified region 7b is performed first, it is preferable to perform the seal surface corona discharge treatment after the laminate surface corona discharge treatment. In general, the degree of corona discharge treatment decreases the longer the time has passed since the film was formed. For this reason, the later the corona discharge treatment is performed, the stronger the conditions of the corona discharge treatment required to achieve the desired surface state must be. Methods for strengthening the conditions of the corona discharge treatment include increasing the energy of the corona discharge treatment and lengthening the time of the corona discharge treatment.

The effect of the corona discharge treatment is most pronounced on the treated surface where the corona discharge treatment is performed, but is also evident on the opposite surface. Therefore, the effect of the corona discharge treatment on the sealing surface is also evident on the laminate surface 12a, and the effect of the corona discharge treatment on the laminate surface is also evident on the sealing surface 12b. The former may have a slight effect on the laminate strength, but is unlikely to be a major problem. On the other hand, the latter affects the seal strength at the sealing portion 3, which can make it difficult to set the sealing conditions, or when peeling at the steam release sealing portion 4, peeling is likely to occur between the sealant layer 2b and the base layer 2a, rather than at the adhesive interface between the sealant layers 2b. For this reason, it is desirable to minimize the effect of the latter. Also, the effect on the opposite surface becomes greater as the conditions of the corona discharge treatment on the treated surface become stronger.

From the above perspective, it is preferable to carry out corona discharge treatment on the laminate surface before corona discharge treatment on the seal surface in order to make the conditions for the corona discharge treatment on the laminate surface as weak as possible.

The corona discharge treatment is preferably performed so that the surface energy of the laminate surface modified region 7a is smaller than the surface energy of the seal surface modified region 7b. This further reduces the effect of the laminate surface corona discharge treatment on the seal surface 12b. The surface energy can be evaluated, for example, by measuring the dyne level using a dyne pen (e.g., manufactured by ARCOTEST). In one example, the dyne level of the seal surface modified region 7b is 42 dynes, and the dyne level of the laminate surface modified region 7a is 38 dynes.

4 to 10, a method for making and filling a bag using the film 2 will be described. This method can be carried out using a vertical type make and fill machine 100.

<S1: Film bending process>
First, the film 2 unwound from the roll F is guided to the former 112 via a number of unwinding rollers 120, 121. A sensor 119 is provided midway along the path from the roll F to the former 112, and is capable of detecting registration marks printed at regular intervals along the length of the film 2, so that a fixed length of the film 2 can be sent out at regular time intervals onto the track of the bag making and filling machine 100. The film 2 is curved into a cylindrical shape while passing through the former 112, and both side edges of the curved tip overlap. An overlapping portion is formed in the overlapping portion.

<S2: Vertical sealing process>
Next, the overlapping portion of the film 2 is heat-sealed by a vertical sealing machine 113 to form a vertical seal portion 31. The vertical sealing machine 113 has a pair of seal rollers, and performs heat sealing while feeding out the film 2 by rotating the pair of seal rollers in opposite directions while holding the overlapping portion of the film 2 in accordance with the timing of the movement of the film 2 at regular time intervals. By forming the vertical seal portion 31 in the film 2, a cylindrical body 5 is formed.

<S3: Horizontal sealing process>
Next, the feed roller 114 is rotated to move the cylinder 5 downstream by a predetermined length, and as shown in Figs. 5 and 6, a predetermined position of the cylinder 5 is heat-sealed by the horizontal sealer 116 to form the horizontal seal section 32. The horizontal seal section 32 is configured by connecting the upper horizontal seal section 32a of the downstream packaging bag 1 and the lower horizontal seal section 32b of the upstream cylinder 5, and is divided into upper and lower parts in a cutting process described later. The horizontal sealer 116 is equipped with a pair of seal bars 116a, and performs heat sealing by clamping the above-mentioned predetermined position with the pair of seal bars 116a for a predetermined period of time. The film 2 has a stripe-shaped modified region 7 formed along the longitudinal direction of the film 2, and the horizontal seal section 32 is formed overlapping the modified region 7 regardless of the position of the film 2 where the horizontal seal section 32 is formed. The portion where the horizontal seal section 32 overlaps the modified region 7 becomes the steam release seal section 4.

<S4: Cutting process>
Next, the feed roller 114 is rotated to move the horizontal seal unit 32 to the position of the press/cutter 118, as shown in Fig. 6. The press/cutter 118 includes a pair of bars 118a.

Next, as shown in FIG. 7, the press/cutter 118 is closed to clamp and cool the horizontal seal portion 32, and the horizontal seal portion 32 is cut with a cutter blade (not shown) to separate it into an upper and lower portion, thereby forming an upper horizontal seal portion 32a of the downstream packaging bag 1 and a lower horizontal seal portion 32b of the upstream cylinder 5, as shown in FIG. 8. Once the horizontal seal portion 32 of the downstream packaging bag 1 has been cut, it falls onto the conveyor 130.

<S5: Filling process>
Next, as shown in Fig. 8, when the squeezing roller 115 is opened, the contents W that were poured from the hopper 111 in the previous process and that have accumulated on the upper side of the squeezing roller 115 fall to the lower side of the squeezing roller 115. Since the lower lateral seal portion 32b is formed in the cylindrical body 5, the fallen contents W are filled into the cylindrical body 5. A molding device 123 is disposed around the cylindrical body 5, and the peripheral surface of the cylindrical body 5 abuts against the molding device 123 to define the outer shape of the cylindrical body 5.

Next, the contents W are further poured into the cylinder 5, and when the contents W in the cylinder 5 reach the position of the sensor 122, the squeezing roller 115 is closed as shown in FIG. 9, dividing the contents W into an upper portion and a lower portion of the squeezing roller 115. The contents in the lower portion of the squeezing roller 115 constitute one bag's worth of packaging bag 1. Furthermore, by closing the squeezing roller 115, a sealed portion 5a is formed in the cylinder 5, and a bag portion 5b is formed between the sealed portion 5a and the lower horizontal seal portion 32b. The packaging bag 1 is formed by forming the upper horizontal seal portion 32a above the bag portion 5b.

<S6: Feeding process>
Next, by rotating the feed roller 114 while keeping the squeezing roller 115 closed, the sealed portion 5a is moved to the position of the horizontal sealer 116 as shown in Fig. 10. Thereafter, the horizontal sealing step is carried out in the same manner as in S3, whereby the horizontal seal portion 32 can be formed at a position (the sealed portion 5a) higher than the portion (the bag portion 5b) filled with the contents W.

After this, steps S1 to S6 can be repeated to continuously produce packaging bags 1 filled with contents W.

The above process produces a packaging bag 1 filled with the contents W. In addition, the steam release seal portion 4 is formed at the portion where the horizontal seal portion 32 overlaps the modified region 7, so that the steam release seal portion 4 can be easily formed without using special equipment. The steam release seal portion 4 is formed at both the upper horizontal seal portion 32a and the lower horizontal seal portion 32b. However, for example, the welding strength at the lower horizontal seal portion 32b may be made higher than the welding strength at the upper horizontal seal portion 32a so that only the portion where the upper horizontal seal portion 32a overlaps the modified region 7 becomes the steam release seal portion 4 (the portion where the lower horizontal seal portion 32b overlaps the modified region 7 has too high a welding strength to become the steam release seal portion 4). The welding strength can be changed by changing the pressing force, seal width, seal temperature, etc. of the seal bar 116a. The horizontal seal portions 32a and 32b may be formed using separate seal bars.

3. Other Configurations: In the above embodiment, the overlapping portion is of a palm-to-palm seal type, but it may be of an envelope seal type. The packaging bag may be of a three-sided seal type, a four-sided seal type, a gusset type, or the like.
The steam release seal portion 4 may be provided at any position in the seal portion 3, for example, in the vertical seal portion 31. In this case, the modified region 7 is formed so that a part or all of the modified region 7 overlaps with the region where the vertical seal portion 31 is formed.

1: Packaging bag 2: Film 2a: Base material layer 2b: Sealant layer 2c: Adhesive layer 2d: Sealing surface 3: Sealing section 4: Steam release sealing section 5: Cylinder 5a: Adhesion section 5b: Bag section 7: Modified area 7a: Laminated surface modified area 7b: Sealing surface modified area 8: Non-sealed section 11: Base material film 12: Sealant film 12a: Laminated surface 12b: Sealing surface 12r: Film roll 13: Die 14: Annular film 15: Roller 16: Flat film 17: Corona discharge treatment device 17a: Anode 17b: Cathode 19: Turning roller 20: Film 21: Turning roller 31: Vertical sealing section 32: Horizontal sealing section 32a: Upper horizontal sealing section 32b: Lower horizontal sealing section 100: Bag making and filling machine 111 : Hopper 112 : Former 113 : Vertical sealer 114 : Feed roller 115 : Squeezing roller 116 : Horizontal sealer 116a : Sealing bar 118 : Press/cutter 118a : Bar 119 : Sensor 120 : Feed roller 121 : Feed roller 122 : Sensor 123 : Forming device 130 : Conveyor F : Rolled raw material W : Contents

Claims (2)

A method for manufacturing a packaging bag, comprising:
The packaging bag is configured by welding a film at a seal portion,
The seal portion includes a steam release seal portion that forms a steam flow path as the internal pressure increases,
The film has a surface that is subjected to a corona discharge treatment to provide a modified region, and is a laminated film in which a base film and a sealant film are laminated,
The sealant film has a lamination surface on the base film side and a sealing surface opposite to the lamination surface,
The modified area is a seal surface modified area in which the seal surface is subjected to a corona discharge treatment,
The laminate surface is provided with a laminate surface modification region in which the laminate surface is subjected to a corona discharge treatment;
The steam release seal portion is a portion where the modified region and its opposing surface are welded together,
The method includes a corona discharge treatment step,
In the corona discharge treatment step, the surface energy of the sealing surface modified region is made larger than the surface energy of the laminate surface modified region,
The method includes performing a corona discharge treatment on a laminate surface to form the laminate surface modified region, and then performing a corona discharge treatment on a seal surface to form the seal surface modified region. 2. The method of claim 1 ,
The method, wherein the laminate surface modification region is larger in area than the seal surface modification region.