JP7835971B2 - packaging bag - Google Patents

Description

This invention relates to packaging bags.

Patent Document 1 discloses a method for sterilizing a laminated film having an adhesive layer by contacting it with a disinfectant consisting of hydrogen peroxide, and then filling the laminated film into bags.

Japanese Patent Publication No. 2015-81142

As described in Patent Document 1, conventional packaging bags made by bag-making and filling had the drawback of being difficult to open.

This invention was made in view of these circumstances and provides a packaging bag that can be easily opened.

According to the present invention, a packaging bag is provided, comprising a multi-layered film, wherein the packaging bag includes a cylindrical body formed by forming a vertical seal portion on the film, an upper horizontal seal portion, a lower horizontal seal portion, and an opening portion. The upper horizontal seal portion is provided to close the upper side of the cylindrical body, and the lower horizontal seal portion is provided to close the lower side of the cylindrical body. If the tensile modulus of the film in the vertical direction along the vertical seal portion is Ve, and the tensile modulus of the film in the horizontal direction along the horizontal seal portion is He, then the relationship Ve < He is satisfied, and the opening portion is formed along the horizontal direction.

This configuration results in a lower tensile modulus in the longitudinal direction than in the transverse direction. This suppresses the stretching of the film in the longitudinal direction when opening the transverse seal, making opening easier.

The following are examples of various embodiments of the present invention. The embodiments shown below can be combined with each other.
Preferably, the opening portion is formed in the upper lateral sealing portion.
Preferably, the upper lateral seal portion has perforations formed as the opening portion.
Preferably, an unsealed portion is formed in the upper lateral seal portion at a position in the direction in which the opening portion extends.
Preferably, the upper limit of the tensile modulus He in the transverse direction of the film is 1000 MPa.

This is a plan view of the packaging bag 1 in the embodiment. This is a plan view of packaging bag 1 as an example of a modified design. This is an explanatory diagram for explaining inflation molding. This is an explanatory diagram illustrating the bag-making and filling method. This figure shows the tensile modulus Ve in the longitudinal direction and the tensile modulus He in the transverse direction of the packaging bag 1 in the example.

The embodiments of the present invention will be described below. The various features shown in the embodiments below are interchangeable. Furthermore, each feature constitutes an independent invention.

1. Packaging bag 1
As shown in Figure 1, a packaging bag 1 according to one embodiment of the present invention comprises a cylindrical body 3 formed by forming a vertical seal portion 7 on a multi-layered film 2, an upper horizontal seal portion 4, and a lower horizontal seal portion 5. The various seal portions can be formed by heat sealing the opposing inner surfaces of the film 2. Normally, the packaging bag 1 is filled with contents, but for convenience, Figure 1 shows the packaging bag 1 in an empty state. Examples of contents include dairy products such as milk and soy milk, and foods such as flower paste, jam, and bean paste.

In the following explanation, the top, bottom, left, and right of Figure 1 will be considered the top, bottom, left, and right of the packaging bag 1. Specifically, the axial direction of the cylindrical body 3 is the vertical direction, and the left and right sides when the vertical seal portion 7 is positioned towards the front are the left and right sides of the packaging bag 1. Furthermore, the side with the vertical seal portion 7 is considered the front, and the opposite side is considered the back.

The length of the packaging bag 1 in the left-right direction is, for example, 140 to 400 mm, and preferably 160 to 300 mm. Specifically, this length is, for example, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, and 400, and may be within the range of any two of the values exemplified here. If this value is too small, the contents may adhere to the inner surface of the packaging bag 1 during bag making and filling, making filling difficult. This problem is particularly noticeable when the contents have high viscosity. The value of [length of packaging bag 1 in the vertical direction / length of packaging bag 1 in the left-right direction] is, for example, 1.1 to 5, and preferably 2 to 4. Specifically, these values could be, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5, and could be within the range of any two of the numbers exemplified here.

The upper lateral seal portion 4 and the lower lateral seal portion 5 are provided to close the upper and lower sides of the cylindrical body 3, respectively. It is preferable that the upper lateral seal portion 4 and the lower lateral seal portion 5 are formed along the upper and lower ends of the cylindrical body 3, respectively. It is also preferable that the upper lateral seal portion 4 and the lower lateral seal portion 5 are formed perpendicular to the vertical seal portion 7.

The vertical seal portion 7 is provided on the gusset portion 8, which is formed by overlapping the inner surfaces of the two side edges of the film 2 after it has been curved into a cylindrical shape. The gusset portion 8 is bent toward one side edge 1a. In the following, "plan view" means viewing the packaging bag 1 flat when it contains no contents, as shown in Figure 1, from a direction perpendicular to the main surface 1b of the packaging bag 1.

If L is the length of the packaging bag 1 in the left-right direction, and L1 is the length of the gusset portion 8 in the left-right direction, then L1/L is preferably between 0.3 and 0.1. Specifically, L1/L may be, for example, 0.1, 0.15, 0.2, 0.25, or 0.3, and may also be within the range of any two of the values exemplified here.

The upper horizontal seal portion 4 is provided with an opening portion 6. The opening portion 6 is a section processed to facilitate the opening of the packaging bag 1. For example, it may be a section where the film 2 is already cut (e.g., a notch, a slit) or a section processed to make the film 2 easier to cut (e.g., a half-cut, a perforation). If the opening portion 6 is the former, there is a risk of the film 2 being unexpectedly torn at the opening portion 6; therefore, it is preferable that the opening portion 6 is the latter. Furthermore, since perforations can be easily formed, it is even more preferable that the opening portion 6 is a perforation.

In the upper horizontal seal portion 4, an unsealed portion 9 is formed on the left side of the opening portion 6 in the left-right direction (i.e., the central side in the left-right direction of the packaging bag 1, hereinafter simply referred to as the central side), in the direction in which the opening portion 6 extends. By forming the unsealed portion 9 in the direction in which the opening portion 6 extends, when the bag is opened from the opening portion 6, the opening is stopped at the central end 9a of the unsealed portion 9, thereby limiting the size of the opening. It is preferable that the opening portion 6 and the unsealed portion 9 are spaced apart. By spacing the opening portion 6 and the unsealed portion 9 in this way, it is possible to prevent the contents from leaking out when the packaging bag 1 is subjected to external impact or other damage to the area near the opening portion 6 of the upper horizontal seal portion 4.

If the length of the opening portion 6 in the left-right direction is L3 and the length of the unsealed portion 9 in the left-right direction is L4, then L3/3 is preferably between 0.7 and 1.2. Specifically, L3/L4 may be, for example, 0.7, 0.8, 0.9, 1.0, 1.1, or 1.2, and may also be within the range of any two of the values exemplified here.

The vertical seal portion 7 may be provided over the entire girdle portion 8, but as the area of the vertical seal portion 7 increases, the time required for heat sealing to form the vertical seal portion 7 increases. Therefore, it is preferable to provide the vertical seal portion 7 on a part of the girdle portion 8. If the length of the vertical seal portion 7 in the left-right direction is L2, then L2/L1 is preferably 1.0 or less, for example, 0.1 to 1.0, specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, and may be within the range of any two of the values exemplified here. Alternatively, the entire girdle portion 8 in the left-right direction may be heat-sealed so that L2/L1 is 1.0. The length L2 of the vertical seal portion 7 in the left-right direction is preferably 30 mm or less.

The film 2 is preferably a laminated film having a base layer and a sealant layer, and more preferably an adhesive layer is provided between the base layer and the sealant layer. In this embodiment, as an example, a five-layer structure is used in which the base layer is sandwiched between sealant layers, and an adhesive layer is provided between the base layer and the sealant layer. The sealant layers are heat-sealed to form a sealed portion. In this case, the sealant layer on the inside of the packaging bag 1 and the sealant layer on the outside may be made of different materials.

The sealant layer can be formed from a resin with excellent heat-sealing properties. For example, the sealant layer can be made from polyethylene (e.g., linear low-density polyethylene). The film constituting the sealant layer is preferably one that has straight-line cut properties in the longitudinal sealing direction.

Furthermore, the sealant layer may be composed of a mixture of multiple resins. In particular, combining resins with low compatibility can impart easy-peel properties. Specifically, a combination of resin composition A and resin composition B can be considered.

Resin composition A: A resin composition whose main component is at least one selected from the group consisting of linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-methyl acrylate copolymer, and ionomers thereof.
Resin composition B: A resin composition whose main component is polypropylene or polybutylene.

The base layer is formed from a material with excellent strength and high impact resistance. Examples of base layer materials include polyamide (nylon), polyolefin, and polyethylene. The adhesive layer is a layer for bonding the base layer and the sealant layer together; examples of adhesive layer materials include polyethylene.

The polyamide in the base layer preferably contains an aromatic polyamide. This is because the base layer has linear cut properties in the longitudinal sealing direction and excellent barrier properties. While there are no particular restrictions on the aromatic polyamide, resins containing 70 mol% or more of polyamide structural units consisting of xylylenediamine and α,ω aliphatic dicarboxylic acids with 6 to 12 carbon atoms in the molecular chain can be used.

Specifically, examples include homopolymers such as polymetaxylylene adipamide, polymetaxylylene pimelamide, polymetaxylylene azeramide, polyparaxylylene azeramide, and polyparaxylylene decanamide, as well as copolymers such as metaxylylene/paraxylylene adipamide copolymer, metaxylylene/paraxylylene pimelamide copolymer, metaxylylene/paraxylylene azeramide copolymer, and metaxylylene/paraxylylene sepacamid copolymer. However, 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.

When bag formation and filling are performed using film 2, the base layer does not come into contact with the contents, while the sealant layer does. Therefore, to suppress the migration of additives to the contents, it is preferable that the sealant material is additive-free. In particular, if the contents are subject to the "Ministerial Ordinance Concerning Standards for Ingredients of Milk and Dairy Products," such as milk, the technical significance of using additive-free materials in the sealant layer is significant. On the other hand, additives such as softeners may be added to the base layer for purposes such as improving the flexibility of film 2.

Furthermore, it is preferable that at least one of the base layer and the sealant layer has straight-cut properties. This is because it makes it easier to tear the film 2 in a straight line. The thickness of the sealant layer is preferably at least twice the thickness of the base layer, and preferably at least half the total thickness of the film 2.

Film 2 can be formed by laminating a substrate layer with a thickness of 10 μm to 20 μm, for example, 15 μm, an adhesive layer with a thickness of 10 μm to 30 μm, for example, 20 μm, and a sealant layer with a thickness of 30 μm to 50 μm, for example, 40 μm. Film 2 typically has a thickness of 50 μm to 100 μm.

2. Modified Version Figure 2 shows a modified packaging bag 1. In the modified version, the non-seal portion 9 formed on the central side of the opening portion 6 extends to the side edge 1a of the packaging bag 1. With this configuration, when the bag is opened from the opening portion 6, the opening is stopped at the side edge 8a of the gusset portion 8, limiting the size of the opening.

3. Method for Manufacturing Film 2 Figure 3 illustrates inflation molding to obtain film 2 used in the multi-layer bag of the present invention. In Figure 3, 30 is an extruder for co-extrusion molding, and 31 is an inflation die. Multiple molten resins extruded from the extruder 30 through the die 31 into a tubular shape are inflated by air supplied from the air supply pipe 32 as they are pulled up vertically. The inflated molten resin is air-cooled by an air-cooling air ring 34, passes through a guide roller 35, a guide plate 38, and a pinch roll 37 in that order, is flattened, and wound onto a winding device 33 to obtain a roll of raw material F in which the tubular film is wound in a flattened shape. Therefore, in the bag-making and filling method described below, the roll of raw material F is unwound and the film 2 is supplied. In this embodiment, by flattening the tubular film, a film 2 is obtained in which an outer film and an inner film are laminated with both edges in the width direction connected. The outer film and the inner film are the outer and inner films of the roll of raw material F, respectively. The multiple-layered film 2 may be manufactured by another method, for example, by laminating and pressing together multiple independent films.

Thus, in this embodiment, the film 2 is formed by inflation molding of a tubular parison extruded by co-extrusion molding, and does not involve a stretching process. Therefore, a film with a low tensile modulus is formed. In this embodiment, the blow ratio during inflation molding is increased, and the extrusion speed is set low.

Specifically, the blow ratio is preferably 1.0 or higher, and more preferably 1.5 or higher. The take-up speed is preferably 100 m/min or less, and more preferably 60 m/min or less. By setting it this way, the relationship Ve < He is satisfied for the tensile modulus of the film 2 in the longitudinal direction (the longitudinal sealing direction) and the tensile modulus of the film 2 in the transverse direction (the transverse sealing direction). By forming the film 2 under these conditions, it is possible to prevent the film 2 from stretching and becoming difficult to open when opening the packaging bag 1 at the opening portion 6 provided in the upper transverse sealing portion 4. The upper limit of the tensile modulus of the film in the transverse direction He is preferably 1000 MPa. For films with a low tensile modulus (i.e., soft), the film may stretch when opened, so the effects of the present invention can be significantly obtained.

The He-Ve value is preferably 1 MPa or higher, and more preferably 3 MPa or higher. This value is, for example, 1 to 100 MPa, specifically, for example, 1, 2, 3, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 MPa, and may be within the range of any two of the values exemplified here, or greater than or equal to either of them. He and Ve are, for example, 300 to 1000 MPa, specifically, for example, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, and 1000 MPa, and may be within the range of any two of the values exemplified here.

4. Bag Forming and Filling Method Next, a bag forming and filling method using film 2 will be described with reference to Figure 4. This method can be implemented using a bag forming and filling system 100 having a sterilization device 13, a drying device 17, and a bag forming and filling device 18. The bag forming and filling method of this embodiment comprises a sterilization step, a drying step, and a bag forming and filling step. Each step will be described in detail below.

4-1. Sterilization Process The sterilization process can be carried out using the sterilization device 13. In the sterilization process, the film 2 unwound from the roll-shaped raw material F is brought into contact with a sterilizing agent to sterilize the film 2.

Specifically, the film 2, first unwound from the roll of raw material F, is guided to the sterilization device 13 via roller 14a. A sensor 119 is placed along the path from the roll of raw material F to the sterilization device 13 to detect registration marks printed at regular intervals along the length of the film 2, enabling the feeding of a fixed length of film 2 onto the trajectory of the bag-making and filling system 100 at regular time intervals. Alternatively, a lateral sealing machine may be placed between the roll of raw material F and the sterilization device 13 to laterally seal the longitudinal end (the direction of film flow) of the film 2. On the other hand, the film 2 may be installed in the bag-making and filling system 100 so that its longitudinal end does not come into contact with the disinfectant. In this case, the lateral sealing machine between the roll of raw material F and the sterilization device 13 is unnecessary.

The sterilization device 13 is a device capable of sterilizing the film 2. It may sterilize the film 2 by immersing it in a sterilization solution 13a, which is a liquid containing a disinfectant, or by bringing the film 2 into contact with a mist or gas of the disinfectant. Hydrogen peroxide is an example of a disinfectant. Within the sterilization device 13, the film 2 is guided by rollers 14b and 14c and moves toward the drying device 17.

After the sterilization process and before the bag-making and filling process, a crimping process is performed to crimp the film 2. Specifically, this process can be carried out by sandwiching the film 2 between a pair of crimping members (e.g., rollers) 15. Performing this crimping process reduces the occurrence of defects during bag making. In this embodiment, a pair of crimping members 15 are provided in two locations, but they may be provided in one or three or more locations.

4-2. Drying Process A drying process is performed after the sterilization process and before the bag-making and filling process. By performing this process, even if moisture or disinfectant adheres to the film 2 during the sterilization process, it is possible to suppress the unintended mixing of moisture or disinfectant into the packaging bag 1.

In this embodiment, the drying process is performed by a blowing device 16 and a drying device 17. The blowing device 16 removes water droplets from the surface of the film 2 by blowing air 16a onto it. The blowing devices 16 are provided on both sides of the film 2, enabling the removal of water droplets from both sides of the film 2.

The internal space 17a of the drying apparatus 17 is at a higher temperature than the external space, allowing the film 2 to dry as it passes through the internal space 17a. The film 2 enters the internal space 17a through the inlet 17b, is guided by rollers 14d, 14e, and 14f within the internal space 17a, and exits through the outlet 17c.

The film 2, having exited the drying apparatus 17, is guided to the former 112 by the roller 14g.

4-3. Bag Making and Filling Process The bag making and filling process can be carried out using a bag making and filling apparatus 18. In the bag making and filling process, the contents W is filled into a cylindrical body 39 formed by heat-sealing the sterilized film 2 to close the lower end, and then the upper end of the cylindrical body 39 is heat-sealed to seal it. This process will be described in detail below.

<First step: Forming film 2 into a tube>
As the film 2 passes through the former 112, it is curved into a cylindrical shape, and the edges on both sides of the curved tip overlap. A girdle portion 8 is formed at the overlapping portion.

<Second step of forming the vertical seal portion 7>
Next, the gusset portion 8 of the film 2 is heat-sealed by the vertical sealing machine 113 to form the vertical sealed portion 7. The vertical sealing machine 113 is equipped with a pair of sealing bars, and heat-seals the gusset portion 8 by clamping it with the pair of sealing bars for a predetermined time in time with the timing of the film 2 moving at regular intervals.

<Third step: Forming the lower lateral seal portion 5>
Next, the openable and closable squeezing roll 115 is closed to squeeze the cylindrical body 39 formed from the film 2. This flattens the cylindrical body 39. Then, a predetermined position of the flattened cylindrical body 39 is heat-sealed by the horizontal sealing machine 116 to form the lower horizontal seal portion 5. The horizontal sealing machine 116 is equipped with a pair of sealing bars, and heat-seals by clamping the predetermined position with the pair of sealing bars for a predetermined time. This closes the lower end of the cylindrical body 39.

<Four steps for filling the contents>
Next, after opening the cutting roll 115, a predetermined amount of contents W is put into the hopper 111 and filled into the cylindrical body 39.

<Fifth step: Forming the upper lateral seal portion 4>
Next, by rotating the feed roll 114, the cylindrical body 39 and the film 2 that follows it are fed out to a predetermined length along with the packaging bag 1 before separation. The pair of sealing bars of the horizontal sealing machine 116 are closed for a predetermined time and heat-sealed at a predetermined position to form the upper horizontal seal portion 4, sealing the packaging bag 1, and also to form the lower horizontal seal portion 5 of the next packaging bag located upstream on the track connected thereto. In this process, an opening portion 6 is formed in the formed upper horizontal seal portion 4. Note that the opening portion 6 may be formed simultaneously with the sixth step of cutting the boundary between the lower horizontal seal portion 5 and the upper horizontal seal portion 4 that is continuous therewith.

<Step 6: Cutting the boundary line of the continuous bag>
The press/cutter 118 is closed to clamp the lower horizontal seal portion 5 and the upper horizontal seal portion 4 that are continuous with it on the lower side of the packaging bag 1 before separation, and the cutter blade 118a cuts the boundary between the two, causing the packaging bag 1 to fall onto the conveyor 130. This produces a packaging bag 1 filled with contents W.

5. Examples Figure 5 shows the longitudinal tensile modulus Ve and transverse tensile modulus He for packaging bag 1 of the examples and packaging bag of the comparative example (units are MPa). The packaging bags of the examples and comparative example were manufactured using the method described in "3. Method for Manufacturing Film 2," and Ve and He were changed by changing the blow ratio. The tensile modulus was determined by performing a tensile test in accordance with JIS K 7127. The test temperature was 23.5°C, the tensile test speed was 50 mm/min, and the dumbbell shape for the test was type 5. As shown in Figure 5, for Examples 1 to 5, the relationship tensile modulus Ve < tensile modulus He is satisfied. In contrast, in the example shown, tensile modulus Ve > tensile modulus He. Experiments were conducted to determine whether these packaging bags of the examples and comparative example could be easily opened.

When the subjects opened the packaging bags 1 of Examples 1 to 5, they were able to easily open them at the opening section 6. In contrast, with the bag shown in the comparative example, the film around the opening section stretched without tearing, making it difficult for the subjects to easily open it.

6. Other Embodiments: The layer configuration of film 2 can be changed as appropriate. In the above embodiment, film 2 has a five-layer configuration including the adhesive layer, but it may have fewer or more layers.
The sealing method of the vertical seal portion 7 of the packaging bag 1 can be changed as appropriate. In the above embodiment, a gusseted gusset portion 8 is formed, but an envelope-style seal may also be used.
- The sterilization and drying processes can be omitted if they are not necessary. Furthermore, the drying process may be performed using only one of the blowing device 16 or the drying device 17, or by natural drying.
In the above embodiment, the opening portion is formed in the upper lateral seal portion 4, but the embodiment is not limited to this. For example, an opening seal portion extending laterally may be provided between the upper lateral seal portion 4 and the lower lateral seal portion 5 in the vertical direction, and the opening portion may be provided in the opening seal portion.

1: Packaging bag 2: Film 3: Cylindrical body 4: Upper horizontal seal section 5: Lower horizontal seal section 6: Opening section 7: Vertical seal section 8: Gusset section 9: Unsealed section 13: Sterilization device 15: Crimping member 16: Blow device 17: Drying device 18: Bag making and filling device 30: Extruder 31: Die 32: Air supply pipe 33: Winding device 34: Air ring for air cooling 35: Guide roller 37: Pinch roll 38: Guide plate 39: Cylindrical body 100: Bag making and filling system 111: Hopper 112: Former 113: Vertical sealing machine 114: Feed roll 115: Roll 116: Horizontal sealing machine 118: Press and cutter 119: Sensor 130: Conveyor

Claims (6)

A packaging bag made of multiple layers of laminated film,
The aforementioned packaging bag is
A cylindrical body formed by forming a vertical sealing portion on the aforementioned film,
Upper side seal section,
Lower side seal section,
Equipped with an opening ,
The aforementioned vertical sealing portion is provided in the girdle portion where the inner surfaces of both side edges of the film are overlapped after the film has been curved into a cylindrical shape.
The aforementioned upper lateral sealing portion is provided to close the upper side of the cylindrical body.
The aforementioned lower lateral sealing portion is provided to close the lower side of the cylindrical body.
Let Ve be the tensile modulus of the film in the vertical direction along the vertical seal portion, and He be the tensile modulus of the film in the horizontal direction along the upper horizontal seal portion. Then the relationship Ve < He is satisfied.
The opening portion is formed along the lateral direction,
A packaging bag in which the upper limit of the tensile modulus of elasticity He in the transverse direction of the film is 1000 MPa . A packaging bag according to claim 1 ,
A packaging bag in which an unsealed portion is formed in the direction in which the opening portion of the upper lateral seal portion extends. The packaging bag according to claim 2,
The opening portion is formed in the upper horizontal seal portion of the packaging bag. The packaging bag according to claim 2,
A packaging bag in which perforations are formed on the upper horizontal seal portion as the opening portion. A packaging bag according to any one of claims 1 to 4,
The aforementioned multi-layered film is formed by flattening a tubular film so that an outer film and an inner film with their edges connected in the width direction are laminated together, or by laminating and pressing together multiple independent films, in a packaging bag. A packaging bag according to any one of claims 1 to 5,
The aforementioned multi-layered film is an inflation film formed by inflation molding, in a packaging bag.