JP6848572B2 - Laminates and packaging bags - Google Patents

Description

The present invention relates to a laminate of resin films used for a packaging bag filled with a liquid and a packaging bag composed of the laminate, and particularly to a laminate and a packaging bag having excellent pinhole resistance.

Pillow packaging bags that store various liquid foods such as water, milk, fruit juice, coffee, tea, sake, vinegar, and soy sauce in a large-capacity packaging bag made of resin film are to be sterilized. It is used after being sterilized with hydrogen peroxide solution, and is called an aseptic pillow packaging bag. As for the resin film constituting the aseptic pillow packaging bag, since it is effective to form a laminate in which a plurality of films are laminated, in addition to the example disclosed in Patent Document 1, laminates having various configurations have been proposed. in use.

As an example, a laminate obtained by laminating low-density polyethylene, high-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin, ethylene-vinyl alcohol copolymer resin, polyester, polyamide and the like is used. However, the aseptic pillow packaging bag made of these laminates is bent many times to form corners due to the flow of the contents due to vibration when it is stored in a box made of corrugated cardboard or the like and transported. May come in contact with the inner wall of the box and be rubbed, causing pinholes. Therefore, the above-mentioned aseptic pillow packaging bag is required to have pinhole resistance.

As a means for improving the pinhole resistance of the aseptic pillow packaging bag, for example, Patent Document 2 includes a biaxially stretched nylon film as an outer layer of a central layer, and a non-stretched nylon film as a central layer and a polyolefin layer on both sides thereof. A laminate of resin films provided with an outer layer portion provided in the above is disclosed, and it is stated that high pinhole resistance is exhibited by enhancing toughness by a central layer containing a biaxially stretched nylon film.

Japanese Unexamined Patent Publication No. 2003-192017 Japanese Unexamined Patent Publication No. 2014-227179

However, the inventors have stated that in the pillow packaging bag made of the laminate disclosed in Patent Document 2, when the packaging bag is stored in a corrugated cardboard box and transported, it is resistant to pinholes against friction with the corrugated cardboard. It has been found that the properties are not sufficient, and the present invention has been achieved, and provides a laminate and a packaging bag in which pinholes are less likely to occur due to contact friction with corrugated cardboard.

In order to solve the above problems, the invention according to claim 1 of the present invention is
A resin film laminate for a liquid-filled packaging bag, which has a surface layer, an intermediate layer, and a sealant layer, and the surface layer is a coextruded film composed of three layers of polyethylene resin / nylon resin / polyethylene resin, and the intermediate layer. Is a stretched nylon resin film, and each of the sealant layers is made of polyethylene resin. Resin layer A (melting point 130 to 150 ° C.) / Resin layer B (melting point 100 to 120 ° C.) / Resin layer C (melting point 130 to 150 ° C.) ) Is a laminated body characterized by having a three-layer structure.

The invention according to claim 2 is
The ratio of the film thicknesses of the resin layer A, the resin layer B, and the resin layer C of the sealant layer is: resin layer A: resin layer B: resin layer C = 0.5 to 2.0: 4.0 to 6.0: The laminate according to claim 1, wherein the thickness is 0.5 to 2.0.

The invention according to claim 3 is
A packaging bag made by laminating the sealant layers of the laminate according to claim 1 or 2.

According to the invention of claim 1, the sealant layer is composed of three layers, the central resin layer B is a low melting point layer having a melting point of 100 to 120 ° C., and the resin layers A and the resin layer C on both sides thereof have a melting point of 130 ° C. By setting the temperature to ~ 150 ° C., the flexibility of the resin layer B is increased, and even if the laminated body is bent, it is difficult to form sharp corners, and even if the corners are formed, the resin layer B becomes corrugated when rubbed against corrugated cardboard. By softening the contact, it is possible to suppress the occurrence of pinholes, which has high pinhole resistance, and the resin layers A and C, which have relatively high melting points on both sides, provide the required adhesive strength and tear strength. A laminate having can be obtained.

Further, according to the invention of claim 2, by setting the ratio of the thickness of each layer of the three-layer sealant layer to a specific range, the strength such as adhesive strength and tear strength and the pinhole resistance are enhanced. Therefore, the balance of flexibility of the entire sealant layer can be made more suitable, and a laminate having more preferable pinhole resistance and strength can be obtained.

According to the invention of claim 3, it is possible to obtain a packaging bag which is hard to form hard and sharp corners, has good pinhole resistance and handleability, and has strength such as adhesive strength and tear strength.

It is sectional drawing of the laminated body of this invention. It is a plan view of the packaging bag of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not construed as being limited to the following embodiments.

FIG. 1 is a schematic cross-sectional view of the laminated body 1 of the present invention. A surface layer 10 which is a co-extruded film composed of three layers of a polyethylene resin layer 11, a nylon resin layer 12, and a polyethylene resin layer 13, an intermediate layer 15 of a biaxially stretched nylon film, and a sealant layer 20 composed of three layers of polyethylene resin layers. Are laminated in this order and are bonded via the adhesive layers 16 and 16. The sealant layer 20 is formed on both sides of a resin layer B22 (melting point 100 to 120 ° C.) made of a polyethylene resin having a relatively low melting point, a resin layer A21 made of a polyethylene resin having a relatively high melting point, and a resin layer C23 (both melting points 130 to 150). ℃) is laminated.

The laminate 1 has a structure having sufficient toughness because it is laminated to form a large-capacity (about 5 liters to 20 liters) aseptic pillow packaging bag, but if the toughness is made too high, the waist strength becomes high. If it is too much, the flexibility will decrease when it is pasted together to make a pillow packaging bag, and when the bag is deformed due to vibration during transportation, sharp corners will be easily formed, and it will be difficult to attach it to the filling machine. It is not preferable because the contents may remain in a large amount or it may be difficult to open the bag. Therefore, it is desirable to make the toughness appropriate according to the capacity of the bag. The toughness is affected by the tear strength, bending strength, etc. of each layer as well as the layer structure, and it is desirable to set these values to appropriate values.

The surface layer 10 of the laminated body 1 is formed by providing polyethylene resin layers 11 and 13 on both sides of a tough non-stretched nylon film 12, and is imparted with resistance to hydrogen peroxide. When the pillow packaging bag is deformed to form corners due to vibration due to transportation or the like, the polyethylene resin layers 11 and 13 are also effective as a buffer layer for suppressing the occurrence of pinholes. The total thickness is preferably about 20 μm to 60 μm. Further, since a large-area film can be easily obtained by using a co-extruded film, it is suitable for forming a large-capacity pillow packaging bag.

The adhesive layer 16 is not particularly limited, but it is preferable to provide, for example, a solvent-free adhesive, a dry lamination adhesive, or the like so as to have a thickness of about 1 to 2 μm at the time of drying. The method of provision is not particularly limited, and for example, known gravure coats, roll coats, knife coats, dip coats, spray coats and the like can be used.

Since the biaxially stretched nylon film constituting the intermediate layer 15 is excellent in toughness, puncture resistance, etc., it is suitable for laminating to form a large-capacity pillow packaging bag. The thickness is preferably about 10 μm to 50 μm, and may be appropriately set so as to meet the required strength according to the size of the bag when the pillow packaging bag is used. Further, the nylon film generally has poor resistance to hydrogen peroxide, but in the laminate 1 having the configuration of the present invention, the surface side of the surface layer 10 which is the outer surface side when made into a packaging bag as described above is against hydrogen peroxide. Since the polyethylene resin layer 11 is resistant and has poor wettability, and the inner surface side is the sealant layer 20 made of polyethylene resin, the nylon film is covered with the sealant layer 20 and the polyethylene resin layer 11 and is exposed on the surface. Therefore, it can be applied to an aseptic pillow packaging bag that requires sterilization treatment with polyethylene without any problem. Further, since the polyethylene resin has poor wettability to hydrogen peroxide, hydrogen peroxide can be quickly removed and dried after sterilization with hydrogen peroxide. When the contents of the pillow packaging bag are milk, at least the resin layer C23 of the sealant layer 20, which is a layer that comes into direct contact with the contents, must be an additive-free polyethylene resin in accordance with the Ordinance of the Ministry of Milk, etc., for example, no additives. The linear low-density polyethylene resin of.

Since the sealant layer 20 serves as the innermost layer of the bag when the laminate 1 is bonded to form a pillow packaging bag, good heat-sealing property is required, and non-stretched polypropylene resin, low-density polyethylene resin, etc. It is known that a polyolefin resin is suitable, but in the embodiment of the present invention, a polyethylene resin such as a low density polyethylene resin, a medium density polyethylene resin, a linear low density polyethylene resin, and a high density polyethylene resin is preferably used. Can be used. Further, the higher the melting point of the polyethylene resin, the less likely it is that the heat-sealed portion will peel off unintentionally, and the higher the tear strength, so it is preferable to apply it to a packaging bag. When used, there is a problem that hard and sharp corners are likely to be formed when the packaging bag is deformed, and pinholes are likely to occur by rubbing against the corrugated cardboard or the like that stores the packaging bag.

On the other hand, in the present embodiment, as shown in FIG. 1, relatively high melting points are formed on both sides of the resin layer B22 made of a polyethylene resin having a relatively low melting point (100 ° C. to 120 ° C.), for example, a linear low-density polyethylene resin. Since the resin layer A21 and the resin layer C23 made of (130 ° C. to 150 ° C.) polyethylene resin, for example, high-density polyethylene resin are laminated, the laminated body 1 is formed by the effect of the low melting point and soft resin layer B22. Flexibility is generated, sharp corners are less likely to occur, and pinholes are less likely to occur even when rubbed against a cardboard. On the other hand, since there are the resin layer A21 and the resin layer C23 having a high melting point, the required tear strength and heat seal strength can be obtained.

In particular, the thicknesses of the resin layer A21, the resin layer B22, and the resin layer C23 have a ratio of resin layer A: resin layer B: resin layer C = 0.5 to 2.0: 4.0 to 6.0: 0. When it is set to 5 to 2.0, a stable laminate 1 having a more favorable balance between heat seal strength, tear strength and flexibility can be obtained, and when it is used for a packaging bag, pinholes are less likely to occur and pinholes are less likely to occur. A packaging bag having sufficient tear strength and heat seal strength can be obtained.

In addition to the above layers, a metal or inorganic oxide vapor-deposited film layer, a printing layer, an overcoat layer, or the like as a barrier layer may be appropriately provided as long as the functions of the layers are not hindered.

As a procedure for producing the laminate 1, coextruding polyethylene resin layers 11 and 13 appropriately selected from low-density polyethylene resin, medium-density polyethylene resin, linear low-density polyethylene resin, and the like are coextruded on both sides of the unstretched nylon film 12. The coextruded film 10 provided by the above and the biaxially stretched nylon film of the intermediate layer 15 are adhered by lamination via the adhesive layer 16 and attached to the other surface of the biaxially stretched nylon film via the adhesive layer 16. It can be manufactured by laminating and laminating the sealant layer 20.

FIG. 2 illustrates an embodiment in which the laminate 1 is laminated with the sealant layer 20 to form a pillow packaging bag 3. The laminate 1 is bent from the left and right, and is sealed in the palm of the hand near the center to form a back seal portion 31, the lower end edge 33 is sealed to form a bag shape, and after the contents are stored, the upper end edge 32 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. Further, when the non-seal portion 34 is projected from the upper end edge 32 and the pillow packaging bag 3 is torn by hand with the notch 35 provided in the side edge portion as a trigger, the tear easily reaches the non-seal portion 34. This makes it easy to open the package. Further, as another form, a spout (not shown) may be provided on the body 36 so that the contents can be opened and closed so that the contents can be filled and poured from the spout.

The following will be described in more detail by way of examples.

<Example 1>
A laminate was created with the following configuration.
Polyethylene resin, nylon resin, polyethylene resin three-layer coextruded film (thickness 40 μm) /
Dry Laminate Adhesive Layer /
Print layer /
Biaxially stretched nylon film (thickness 15 μm) /
Dry Laminate Adhesive Layer /
Sealant layer: Resin layer A (additive-free polyethylene having a melting point of 143 ° C.) (thickness 11 μm)
Resin layer B (additive-free polyethylene with a melting point of 118 ° C) (thickness 56 μm)
Resin layer C (additive-free polyethylene with melting point 143 ° C) (thickness 11 μm)
An evaluation test was carried out on the prototype laminated body sample according to the items and measurement methods shown in Table 1.

<Comparative example 1>
Sealant layer: Additive-free polyethylene with a melting point of 143 ° C (thickness 75 μm)
A laminate sample similar to that in Example 1 was produced and evaluated in the same manner.

The evaluation results are shown in Table 2.
Of the results, the numerical values are the average values of each sample, and the square pinholes are marked with ◯ when no pinholes occur in all the samples.

As shown in Table 2, in the laminated body of the present invention, by providing the polyethylene layer having a low melting point in the sealant layer, the sealant layer has lower waist strength and increased flexibility as compared with the single-layered laminated body. Was confirmed. It was also confirmed that excellent results can be obtained even with the occurrence of square pinholes. Further, in the bending strength test and the tear strength test, the results of the sealant layer were similar to those of the single-layered laminated body, and the toughness of the laminated body was not lowered.

1 ... Laminated body 3 ... Packaging bag 10 ... Surface layers 11, 13 ... Polyethylene resin layer 12 ... Nylon resin layer 15 ... Intermediate layer 16 ... Adhesive layer 20 ... Sealant layer 21 ... Resin layer A
22 ... Resin layer B
23 ... Resin layer C
31 ... Back seal part 32 ... Upper edge part 33 ... Lower edge part 34 ... Non-seal part 35 ... Notch 36 ... Body part

Claims (3)

A resin film laminate for a liquid-filled packaging bag, which has a surface layer, an intermediate layer, and a sealant layer, and the surface layer is a coextruded film composed of three layers of polyethylene resin / nylon resin / polyethylene resin, and the intermediate layer. Is a stretched nylon resin film, and each of the sealant layers is made of polyethylene resin, resin layer A (melting point 130 to 150 ° C.) / resin layer B (melting point 100 to 120 ° C.) / resin layer C (melting point 130 to 150 ° C.). ), A laminated body characterized by having a three-layer structure. The ratio of the film thicknesses of the resin layer A, the resin layer B, and the resin layer C of the sealant layer is: resin layer A: resin layer B: resin layer C = 0.5 to 2.0: 4.0 to 6.0: The laminate according to claim 1, wherein the thickness is 0.5 to 2.0. A packaging bag prepared by laminating the sealant layers of the laminate according to claim 1 or 2.

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