JPH0999957A - Easily openable packaging bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the unsealing, and at the same time, improve the appearance of the unsealed surface by a method wherein for an easily openable packaging bag made of a laminated film for which a base material, an intermediate layer, and a sealant layer are laminated in order, polyethylene is used for one of the intermediate layer or the sealant layer, and polypropylene is used for the other layer. SOLUTION: An easily openable packaging bag is formed of a laminated film 10 for which a base material 11, an intermediate layer 12 and a sealant layer 13 are laminated in order, and one of the intermediate layer 12 and the sealant layer 13 is made of polyethylene, and the other is made of polypropylene. For example, a drawn polypropylene film 11a and a drawn polyester film 11b are sand-laminated, and the obtained film is made the base material 11. Then, on the polyester film surface of the base material 11, polyethylene is laminated as the intermediate layer 12, and polypropylene is laminated on the innermost layer which becomes the sealant layer 13 in order to form the laminated film 10, and a hut-affixed bag is made using the laminated film 10. Therefore, the packaging bag to be used for snack food can be easily opened by hand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging bag made of a laminate, and more particularly to a packaging bag which can be easily opened.

[0002]

2. Description of the Related Art Conventionally, in a packaging bag represented by snacks such as potato chips, the outside air is shut off to prevent deterioration of the contents to prevent oxidation of the contents, or to prevent the contents from being promoted by shading. It has a function. It also has a function of preventing the quality of the contents from deteriorating due to moisture absorption during storage or conversely drying.

[0003] These packaging bags are generally sealed by heat fusion with a heat seal layer provided on the inner surface. Therefore, in order to achieve the above-mentioned purpose of the packaging bag, it is necessary that this heat-sealing layer has a sufficient sealing property, and that the heat-sealing layer has sufficient heat-sealing so that the sealing portion does not come off during transportation or the like. It is required to have strength.

However, excessive heat-sealing strength for protecting the contents, on the contrary, cannot be easily opened by hand when used by the consumer, and it is less necessary to use tools such as scissors. There wasn't. In addition, even if it can be opened, it requires a large amount of force when opening, and the content pops out at the moment of opening, and the opening interface is cohesively destroyed, which is not aesthetically pleasing. It was From such a problem, there has been proposed a packaging bag which has a sufficient sealing property for protecting the contents and which can be easily opened by hand.

[0005] As a proposal of easy opening in a packaging bag,
Proposals have been made for a long time to reduce the heat seal strength by blending the resin composition of the sealant layer with a polymer. However, unlike the bonding of different polymers such as the relationship between the cup container and the lid material, the packaging bag is bonded to the same polymer, and therefore has not yet been provided with the easy-open function. In addition, threading may occur at the adhesive interface when the packaging bag is opened, which is not aesthetically pleasing and may cause the threaded resin to mix into the contents.

Further, in the lid material of the plastic container,
A base material on the sealant layer of the lid material and a blend layer using polypropylene as a base resin on the base material side, a polypropylene layer is sequentially laminated on the innermost layer by coextrusion, and delamination is performed between the blend layer and the polypropylene layer, A method of imparting easy opening property has been proposed. However, there are problems that still have to be solved, such as stringing between the blend layer and the polypropylene layer and the fact that the easy-opening property is not exhibited.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention is an easy-open packaging bag which is easy to open and has an aesthetically good opening surface. The challenge is to provide.

[0008]

In order to achieve the above object, the present invention is, according to a first aspect of the invention, an easily openable packaging bag comprising a laminated film in which a base material, an intermediate layer and a sealant layer are sequentially laminated. One of the intermediate layer and the sealant layer is polyethylene, and the other is polypropylene.

The second aspect of the present invention provides an easy-open packaging bag characterized by using polyethylene for the intermediate layer and polypropylene for the sealant layer.

Further, the third invention provides an easily openable packaging bag according to the first invention, wherein polypropylene is used for the intermediate layer and polyethylene is used for the sealant layer.

[0011]

When the sealant layers of the laminated film having the above-mentioned constitution are heat-sealed, the same polymers are sealed, so that a strong sealing strength can be obtained, and the sealing property and the protective function of the contents can be obtained. Is maintained. In addition, the polyethylene layer and the polypropylene layer are melted by the heat of the heat sealer, and in the process of being cooled again, the laminate strength between the two layers is reduced due to the difference in the crystallization rate between the two layers, so the sealant layer is sealed at the time of opening. It is easy to cut from the edge part. Then, after the sealant layer is cut off, delamination occurs between the polyethylene layer and the polypropylene layer. At this time, since the laminate strength of the seal portion is lowered due to the above-mentioned reason, smooth opening is performed. Further, since the polyethylene layer and the polypropylene layer have low compatibility, no stringing occurs and the unsealed surface is aesthetically excellent because the intermediate layer is exposed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The easy-open packaging bag according to the present invention has a laminate strength of polyethylene layer and polypropylene layer of 30 gf /
15 mm or more and 500 gf / 15 mm or less, preferably 5
The structural feature is 0 gf / 15 mm or more and 200 gf / 15 mm or less, and the intermediate layer has a polyethylene layer and the sealant layer has a polypropylene layer, or the intermediate layer has a polypropylene layer and the sealant layer has a polyethylene layer.

As the polypropylene used in the present invention, a homopolymer of propylene, a random copolymer with ethylene, butene-1, pentene-1, hexene-1, etc., or a block copolymer may be used. it can. In the case of these copolymers, it becomes amorphous depending on the ratio of the copolymerization components, but it is preferable to use crystalline polypropylene having a density of 0.89 or more in terms of processability, suitability for contents, resistance and the like. preferable.

As the polyethylene used in the present invention, homopolymers such as high-density polyethylene, medium-density polyethylene and low-density polyethylene, butene-1, pentene-1, hexene-1, 4-methyl-pentene-1, Linear low-density polyethylene that is a copolymer with octene-1, etc., and ethylene-α polymerized using a single-site catalyst
It can be selected from olefin copolymers and the like. Further, these polyethylenes may be blended and used.

The molding method of the sealant layer of the packaging bag in the present invention is to extrude the intermediate layer and the sealant layer by a coextrusion method to adhere them to the substrate, or to use polyethylene or polypropylene on the polypropylene or polyethylene film as the sealant layer. Polypropylene or polyethylene may be sequentially extruded and laminated.

[0017]

[Examples] Specific description will be given below based on examples.
The present invention is not limited to the following. Example 1 A stretched polypropylene film (11a) having a thickness of 20 μm and a stretched polyester film (11b) having a thickness of 12 μm are made into polyethylene (11c) having a thickness of 15 μm.
Was sand-laminated as above and used as a base material (11). Then, L5816 (density 0.917, melt flow rate 10, manufactured by Sumitomo Chemical Co., Ltd.), which is polyethylene, was used as the intermediate layer (12) on the polyester film surface of the base material (11) with a thickness of 15 μm and a sealant. The innermost layer to be the layer (13) is polypropylene F
L25R (density 0.89, melt flow rate 23
(230 ° C., manufactured by Mitsubishi Chemical Co., Ltd.) having a thickness of 20 μm was laminated by a coextrusion method so as to be laminated in order to prepare a laminated film (10) having a five-layer structure.

The laminated film (1
0), the surface of the coextruded polypropylene was put together, and the size was 200 m as shown in FIG. 2 by the heat sealing method.
A m-150 mm joint-sealed pouch (20) was produced. As a result of attempting to open the joint-sealed pouch, the feeling of opening was smooth and the opened surface was good.

Example 2 Using the same substrate as in Example 1,
FL25R (density 0.89, melt flow rate 23 (230 ° C), manufactured by Mitsubishi Chemical Corporation), which is polypropylene, is applied to the polyester film surface of this base material 15
After being extruded with a thickness of μm, as a sealant layer which is the innermost layer, affinity PT1450 (density 0.902, which is polyethylene produced by a metallocene catalyst,
Melt flow rate 7.5 (manufactured by Dow) was extruded on the polypropylene surface to prepare a 5-layer film.

Of the laminated film thus produced,
The same polyethylene surface as the sealant layer was heat-sealed to obtain the same 200 mm × 150 m as in Example 1.
A m-shaped joint bag was prepared. As a result of attempting to open the gas-sealed pouch, the feeling of opening was smooth and the surface to be opened was good as in Example 1.

<Comparative Example 1> Using the same substrate as in Example 1,
On the polyester film side of this base material, polypropylene FL25R (density 0.89, melt flow rate 23 (230 ° C), manufactured by Mitsubishi Chemical Corporation) 30
A four-layer film was produced by extrusion lamination with a thickness of μm.

Of the laminated film thus produced,
The same polypropylene surface as the sealant layer was heat-sealed to obtain the same 200 mm × 150 as in Example 1.
A mm-sized pouch attached bag was prepared. Attempts were made to open the pouch with the palm-sealed joint, but it was not preferable because it was difficult to open, and the open surface had an uneven pattern or a mustache-like stringing.

Comparative Example 2 Using the same base material as in Example 1,
Unilux RS- which is a co-extruded film of unstretched polypropylene with the polyester film side of this substrate
512 (manufactured by Idemitsu Petrochemical Co., Ltd.) was sand laminated with Mirason 14P (density 0.92, melt flow rate 5.2, manufactured by Mitsui Petrochemical Co., Ltd.), which is low-density polyethylene, to produce a five-layer film. .

Of the laminated film thus produced,
The same polypropylene surface as the sealant layer was heat-sealed to obtain the same 200 mm × 150 as in Example 1.
A mm-sized pouch attached bag was prepared. An attempt was made to open the pouch with the jointed palm, but it was difficult to open the bag as in Comparative Example 1, and
The unsealed surface had an uneven pattern and mustache-like stringing, which was not preferable.

Further, the sealant layers of the three types of laminated films of Example 1 and Comparative Examples 1 and 2 were combined, and the pressing pressure was 2 kgf / cm ² , the heat sealing time was 1 second, and the heat sealing temperature was 140 to 160 ° C. Heat sealing was performed under the conditions of. This was cut into a strip shape with a seal width of 15 mm, and 300 mm / min. The heat seal strength was measured at the speed of. The results are shown in Table 1 and changes in heat seal strength during measurement are shown in FIG.

[0026]

[Table 1]

Considering from Table 1 and FIG. 3, Comparative Examples 1 and 2 have a high heat seal strength, and a high load is maintained until peeling is completed, while Example 1 has a heat load. It can be seen that the seal strength is weak, and the load is momentarily applied at the start of peeling, but thereafter the peel strength changes to a small value.

[0028]

As described above, according to the present invention, in a packaging bag made of a multi-layered film for storing snacks and the like, it is necessary to satisfy the contradictory functions of protection (sealing property) and easy opening property of the contents. It was difficult with the sealing method of. However, since the seal layer and the peeling layer are different, the heat-sealing strength does not affect the heat-sealing, and the opening is smoothly performed, and both functions are ensured.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a cross section of an example of a layer structure of an easy-open packaging bag of the present invention.

FIG. 2 is an explanatory view of an easy-open packaging bag showing an embodiment of the present invention.

FIG. 3 (a) shows the heat seal strength in Example 1,
It is a figure showing the relationship between pulling time and heat seal strength. (B) It is a figure showing the relationship between the pulling time and the heat-sealing strength of the heat-sealing strength in Comparative Example 1. (C) It is a figure showing the relationship between the pull time and the heat seal strength of the heat seal strength in Comparative Example 2.

[Explanation of symbols]

 10 Laminated film 11 Base material 11a Stretched polypropylene film 11b Stretched polyester film 11c Polyethylene 12 Intermediate layer 13 Sealant layer 20 Easy-open bag

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomatsu Takeshi 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd.

Claims (3)

[Claims] 1. An easily-openable packaging bag comprising a laminated film in which a base material, an intermediate layer and a sealant layer are sequentially laminated, wherein one of the intermediate layer and the sealant layer is polyethylene and the other is polypropylene. Easy to open packaging bag. 2. Polyethylene is used for the intermediate layer and polypropylene is used for the sealant layer.
The easy-open packaging bag described in. 3. The polypropylene is used for the intermediate layer, and the polyethylene is used for the sealant layer.
The easy-open packaging bag described in.