JP2019135089A - Laminated film, packaging bag and package - Google Patents

Abstract

To provide the laminated film and the packaging bag, that are less likely to generate pinholes even in a case of contact friction with cardboard.SOLUTION: The laminated film 10 comprises an outer layer 18, an intermediate layer 15, and an inner layer 17 in order of lamination, wherein the outer layer is formed by laminating polyolefin resin layers 11, 13 on both sides of a center layer 12 including an unstretched nylon film, the intermediate layer is formed by a biaxially stretched nylon film, the inner layer is formed by linear low density polyethylene, and the unstretched nylon film is a copolymer of 6-nylon and 6,6-nylon.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminated film of a resin film used for a packaging bag filled with a liquid and a packaging bag constituted by the laminated film, and more particularly to a laminated film and a packaging bag excellent in pinhole resistance.

  A packaging bag in the form of pillow packaging that contains various liquid foods such as water, milk, fruit juice, coffee, tea, liquor, vinegar, and soy sauce in a large-capacity packaging bag made of a resin film. It is used after being sterilized with hydrogen peroxide or the like, and is called an aseptic pillow packaging bag. Since it is effective to use a laminated film in which a plurality of films are laminated as the resin film constituting the aseptic pillow packaging bag, laminated films having various configurations have been proposed and used.

  For example, a low-density polyethylene, high-density polyethylene, polypropylene, an ethylene / vinyl acetate copolymer resin, an ethylene / vinyl alcohol copolymer resin, a laminated film obtained by laminating polyester, polyamide, or the like is used. However, the aseptic pillow packaging bag made of these laminated films is thick and hard because the laminated film itself is suitable for large-capacity packaging, and the number of times as the contents flow when it is stored in a cardboard box and transported. When bent, a corner may be formed, and the corner may be rubbed against the inner wall of the cardboard box to generate a pinhole. For this reason, the laminated film and the aseptic pillow packaging bag are required to have pinhole resistance.

  As a means for enhancing the pinhole resistance of the laminated film and the aseptic pillow packaging bag, for example, Patent Document 1 discloses a polyolefin layer having an unstretched nylon film as a central portion on an outer layer of a center layer composed of a biaxially stretched nylon film. A laminated film of a resin film provided with outer layer portions provided on both sides thereof is disclosed, and pinhole resistance is exhibited by a central layer including a biaxially stretched nylon film.

  Patent Document 2 discloses a laminated film having the same structure as Patent Document 1, and by forming a biaxially stretched nylon film constituting the central layer using a tubular method, pinhole resistance is improved. An improved laminated film is obtained.

Japanese Patent No. 6127711 JP 2016-222277 A

  However, the inventors, in the pillow packaging bag made of the laminated film disclosed in Patent Literature 1 and Patent Literature 2, when transporting the packaging bag in a cardboard box, or in the so-called bag-in-box packaging In the case of the body, it has been found that the pinhole resistance to the friction with the cardboard box is still not sufficient, and has led to the present invention, the possibility of generating a pinhole also by contact friction with the cardboard It is an object to provide a few laminated films and packaging bags.

In order to solve the above problems, the invention according to claim 1 of the present invention provides:
A laminated film in which an outer layer, an intermediate layer, and an inner layer are laminated in this order,
The outer layer is formed by laminating a polyolefin resin layer on both sides of a center layer including an unstretched nylon film,
The intermediate layer is made of a biaxially stretched nylon film,
The inner layer is made of linear low density polyethylene,
The unstretched nylon film is a laminated film characterized by being a copolymer of 6-nylon and 6,6-nylon.

The invention according to claim 2 of the present invention is
The laminated film according to claim 1, wherein the polyolefin resin layer is a medium density polyethylene resin layer.

The invention according to claim 3 of the present invention is
The laminated film according to claim 1 or 2, wherein the outer layer and the intermediate layer, and the intermediate layer and the inner layer are bonded to each other with a solventless adhesive.

The invention according to claim 4 of the present invention is
It is a pillow packaging bag which consists of a laminated | multilayer film in any one of Claim 1 to 3, It is a packaging bag characterized by the above-mentioned.

The invention according to claim 5 of the present invention is
A packaging body of a bag-in-box type in which the packaging bag according to claim 4 is filled with a liquid and stored in a cardboard box.

  According to the invention described in claim 1 of the present invention, the center layer of the outer layer is a copolymer of 6-nylon and 6,6-nylon, so that the laminated film becomes soft and molded into a bag shape. When the liquid content is filled, the corners of the laminated film formed by bending the laminated film become softer, so that the laminated film is repeatedly bent and the cardboard when stored in a cardboard box. A laminated film that can suppress the generation of pinholes due to friction with the box or the like can be provided.

  Further, according to the invention described in claim 2, high strength polyethylene which is high in strength but poor in flexibility and easily forms pinholes when bent, and low density polyethylene which is high in flexibility but inferior in mechanical strength. There can be provided a laminated film having no drawbacks and having a balance between pinhole resistance and strength.

  Further, according to the invention described in claim 3, it is possible to provide a laminated film that does not affect the odor and contents of the residual solvent when used in a packaging bag.

  Further, according to the invention described in claim 4, it is possible to provide a pillow packaging bag having good pinhole resistance and applicable to sterilization treatment with hydrogen peroxide.

  According to the fifth aspect of the present invention, a bag-in-box type package in which the pillow packaging bag stored in the cardboard box is less likely to cause pinholes due to friction with the inner surface of the cardboard box is obtained.

It is a layer block diagram of the laminated | multilayer film of this invention. It is an external appearance schematic diagram of the packaging bag of this invention. It is the schematic diagram of the aspect which accommodated the packaging bag of this invention in the cardboard box.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below.

  FIG. 1 is a schematic cross-sectional view of a laminated film 10 of the present invention. An inner layer 17 of linear low density polyethylene (hereinafter referred to as LLDPE) is provided on one side of the intermediate layer 15 of the biaxially stretched nylon film, and an outer layer 18 is provided on the other side of the intermediate layer 15. Is provided. The outer layer 18 is composed of an unstretched nylon film, which is a copolymer of 6-nylon and 6,6-nylon, as a central layer 12, and polyolefin resin layers 11 and 13 provided on both sides thereof. Solventless adhesive layers 14 and 16 are provided between the outer layer 18 and the intermediate layer 15 and between the intermediate layer 15 and the inner layer 17, respectively, and are bonded together as a whole.

  The laminated film 10 can be formed into a packaging bag by bonding the laminated film 10 so that the inner layer 17 faces the inside of the bag. The laminated film 10 has a structure having toughness so as to make an aseptic pillow packaging bag having a large capacity (about 5 to 20 liters). On the other hand, if the toughness is increased too much such as by increasing the thickness, the waist strength becomes too high. In addition, when a pillow packaging bag is pasted together, the flexibility is reduced and the corners are easily formed when the bag is deformed, and it is difficult to attach to the filling machine, and the content remains more. Since it may be difficult to open the bag, it is desirable to have appropriate toughness and flexibility depending on the capacity of the bag.

  Since the biaxially stretched nylon film of the intermediate layer 15 is excellent in toughness, puncture resistance and the like, it is suitable for bonding to form a large-capacity pillow packaging bag. The thickness is, for example, about 10 to 50 μm, preferably 10 to 25 μm, and may be set so as to meet the required strength according to the size of the bag when making a pillow packaging bag.

  On the other hand, when the outer layer 18 is made of a non-stretched nylon film, which is a copolymer of 6-nylon and 6,6-nylon, as the center layer 12, the flexibility is increased and the waist strength is lowered. The corners can be made difficult to form. In addition, even when corners are formed, the flexibility of the corners is increased and pinholes due to friction with the cardboard are difficult to be formed. This is presumed to be due to inhibition of crystallization of 6-nylon by using a copolymer of 6-nylon and 6,6-nylon. As described above, in the laminated film of the present invention, both toughness and flexibility can be achieved by combining and laminating nylon films having different properties.

  The outer layer 18 is also provided with resistance to hydrogen peroxide by coextruding polyolefin resin layers 11 and 13 on both sides of the central layer 12 of a highly flexible unstretched nylon film. In addition, when the pillow packaging bag is deformed due to vibration due to transportation or the like to form a corner portion when it is formed into a pillow packaging bag, the polyolefin resin layers 11 and 13 are also used as buffer layers to cause pinholes due to friction with the cardboard and repeated bending. Suppresses the occurrence of For this reason, it is more preferable that the polyolefin films 11 and 13 are medium density polyethylene resins having a good balance between toughness and flexibility. The total thickness is preferably about 20 to 60 μm. Further, when the outer layer 18 is manufactured by coextrusion, a film having a large area can be easily obtained, which is suitable for forming a large-capacity pillow packaging bag.

Since the inner layer 17 is bonded as an innermost layer of a bag when the laminated film 10 is bonded to form a pillow packaging bag, good heat sealability is required, and it is preferable to use LLDPE. The thickness is, for example, about 10 μm to 100 μm, and preferably 50 to 100 μm. Further, since LLDPE has poor wettability to hydrogen peroxide, it can be quickly removed and dried after sterilization with hydrogen peroxide. In addition, when the contents of the pillow packaging bag are milk, the inner layer 17 that is also a layer that directly touches the contents according to the regulations of the Ordinance of Milk and the like must be made of an additive-free polyethylene resin, and an additive-free linear low density A polyethylene resin is used.

The solventless adhesive layers 14 and 16 are not particularly limited, but are preferably provided so as to be about 0.5 to 5 g / m ^{2 in a} dry state, for example. The method of providing is not particularly limited, and for example, a known gravure coat, roll coat, knife coat, dip coat, spray coat or the like can be used. By making the adhesive layer solvent-free, there is no residual solvent odor, and it is not necessary to dry at a high temperature to evaporate the solvent, so that the unstretched nylon film of the center layer 12 is prevented from shrinking due to heat. be able to.

  Nylon films generally have low resistance to hydrogen peroxide, but in the laminated film 10 having the above-described configuration, the nylon films of the intermediate layer 15 and the center layer 12 are covered with an inner layer 17 of LLDPE or a polyolefin resin layer 11. Since it is not exposed on the surface, it can be applied without problems to an aseptic pillow packaging bag that requires sterilization treatment with hydrogen peroxide.

  In addition to the above layers, a metal or inorganic oxide vapor deposition film layer, a printing layer, an overcoat layer, or the like as a barrier layer may be appropriately provided as long as the function of each layer is not hindered.

  As a procedure for producing the laminated film 10, between the outer layer 18 provided by coextrusion of the polyolefin resin layers 11 and 13 on both sides of the center layer 12 of the unstretched nylon film, and the biaxially stretched nylon film of the intermediate layer 15, It can be manufactured by providing a solventless adhesive layer 14, providing a solventless adhesive layer 16 between the intermediate layer 15 and the inner layer 17, laminating and laminating.

  FIG. 2 illustrates an embodiment in which two laminated films 10 are bonded together with an inner layer 17 to form a pillow packaging bag 20. The laminated film 10 is bent from the left and right, and a back seal portion 23 is formed by sealing with a palm in the vicinity of the center, and the seal portion 22 at the lower end edge is sealed to form a bag shape. The sealing portion 21 is sealed and sealed. If the capacity is large, for example, about 5 liters, the outer shape is a pillow packaging bag having a length of about 500 mm and a width of about 300 mm. Although not shown in particular, in order to facilitate opening, notches are provided in the seal portions 21 and 22 at the edge, and a stopper is provided in the storage portion 24 so that the container can be opened and closed. You may be able to do.

  When the packaging bag 20 stores the contents, the packaging bag 20 swells from a flat state, and thus may be distorted to form corners 25a, 25b, and 25c. However, the packaging bag 20 of the present invention has moderate flexibility. Therefore, the occurrence of corners is relatively small, and when it occurs, it becomes a relatively flexible corner and hardly forms a sharp corner.

  FIG. 3 shows a bag-in-box-shaped package in which the packaging bag 20 of the present invention is stored in a cardboard box 30. The pillow packaging bag stored in the cardboard box may be deformed by vibration during transportation or the like, and the generated corner may be rubbed in contact with the inner surface of the cardboard box to form a pinhole. The laminated film 10 constituting the bag 20 has moderate flexibility, particularly when the laminated film is repeatedly bent due to movement of the pillow packaging bag in the cardboard box, or when the inner surface and corners of the cardboard box are rubbed. Generation of pinholes can also be suppressed at the portion 26 and the like.

  Examples will be described in more detail below.

<Example 1>
A laminate was prepared with the following configuration.
Outer layer: medium density polyethylene resin / center layer: unstretched film of 6-nylon and 6,6-nylon copolymer / medium density polyethylene resin (total thickness 40 μm)
/ Solvent-free adhesive layer /
Intermediate layer: printing layer / stretched nylon film (thickness 15 μm)
/ Solvent-free adhesive layer /
Inner layer: LLDPE (thickness 75μm)

  About the laminated body sample made as an experiment, the evaluation test was done by the item and the measuring method which are shown in Table 1.

<Comparative Example 1>
A conventional laminated film having the same structure as that of Example 1 was produced except that the center layer of the outer layer was an unstretched 6-nylon film, and an evaluation test was performed.

The evaluation results are shown in Table 2.
Of the results, the numerical value is an average value of each sample, and for square pinholes, the case where no pinholes occurred in all the samples was indicated as ◯, and the case where even one occurred was indicated as x.

  As shown in Table 2, it was confirmed that in the laminate of the present invention, a result superior to that of the laminate having the conventional configuration was obtained due to the generation of square pinholes. In addition, it was confirmed that the softening was successfully performed in the bending test and the waist strength test.

DESCRIPTION OF SYMBOLS 10 ... Laminated body 11, 13 ... Polyolefin resin layer 12 ... Center layer 14, 16 ... Solventless adhesive layer 15 ... Intermediate layer 17 ... Inner layer 18 ... Outer layer 20 ··· Packaging bag 21 ··· Sealing portion 22 at upper edge ··· Sealing portion 23 at lower and lower edge ··· Back sealing portion 24 · · · Storage portions 25a, 25b, 25c Part 30 where the corners are rubbed ... Cardboard box

Claims (5)

A laminated film in which an outer layer, an intermediate layer, and an inner layer are laminated in this order,
The outer layer is formed by laminating a polyolefin resin layer on both sides of a center layer including an unstretched nylon film,
The intermediate layer is made of a biaxially stretched nylon film,
The inner layer is made of linear low density polyethylene,
A laminated film, wherein the unstretched nylon film is a copolymer of 6-nylon and 6,6-nylon.   The laminated film according to claim 1, wherein the polyolefin resin layer is a medium density polyethylene resin layer.   The laminated film according to claim 1 or 2, wherein the outer layer and the intermediate layer, and the intermediate layer and the inner layer are bonded to each other with a solventless adhesive.   It is a pillow packaging bag which consists of a laminated film in any one of Claim 1 to 3, The packaging bag characterized by the above-mentioned. A package in a bag-in-box format in which the packaging bag according to claim 4 is filled with a liquid and stored in a cardboard box.

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