JPH09156016A - Packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set the strength between layers which is desired to be released properly weak, thereby to control the seal strength of a seal section by providing a laminate interface of the release strength smaller than the release strength of a printed layer surface. SOLUTION: The layer structure of a packaging material is, for instance, the laminate constitution in which an intermediate layer 13 is formed on a base material 11 with a printed layer 12, over which a sealant layer 14 is formed. The release strength among respective layers of a laminated film as a packaging material, or more preferably the release strength of an interface between an intermediate layer 13 and the sealant layer 14, or that of one interlaminar interface of the intermediate layer 13 as a multilayer is set to be weaker than the release strength of a printed face 12 forming an ink face and the base material layer 11 and the ink face and the intermediate layer 13. When a hutt seal bag is formed by the heat seal method in which the sealant layers 14 of the packaging material are joined together and the bag is opened from the seal section, the bag can be easily opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material having a multilayer structure composed of laminated films, and more particularly to a packaging material having a laminating interface having a peel strength smaller than the peel strength of a printed layer surface.

[0002]

2. Description of the Related Art Conventionally, in a packaging material having a multilayer film structure for packaging articles such as snacks such as potato chips, each layer is firmly adhered to form a sealant at the time of forming a bag. The bag is easy to peel and has an openability. In such a case, however, the sealant portion is so strong that it cannot be easily opened by hand when used by a consumer, and it is often the case that tools such as scissors must be used. In addition, a large force is required at the time of opening, and even if it can be opened, the contents will pop out at the moment of opening and the opening interface will be destroyed, which is not aesthetically pleasing. From such a problem, a packaging bag using a packaging material having a multi-layered structure, which has sufficient sealing property for protecting the contents and can be easily opened by hand, has been proposed.

As a proposal of easy-opening property, for example, as shown in FIG. 6, a film (for example, unstretched polypropylene film) which is difficult to adhere to an extruded resin (for example, polyethylene) is used as the sealant layer (54), and the sealant layer and the base are used. There is a method of sandwich laminating the material layer (51) and the adhesive layer (53) with molten polyethylene.
In this case, the printed layer (52) is provided on the entire surface or a part of the base material layer (51) as needed. A packaging bag produced using the packaging material (50) obtained by this method is
After the unstretched polypropylene film, which is the sealant layer, is first destroyed, it is possible to open it with a fairly weak force along the peeling surface of the sealant layer and the polyethylene resin layer, which is the adhesive layer. Due to weak adhesion between layers, delamination may occur in the entire packaging bag.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned problems relating to a packaging material having a multi-layered structure and used for an easily-openable packaging bag. An object of the present invention is to provide a packaging material having a laminated interface having a peel strength smaller than that of the above. This is because, in a packaging material having a multi-layered structure, when the sealant layer has a high seal strength, the peel strength of each layer interface is adjusted and the peel strength between the layers to be peeled is appropriately weakened to set the seal portion. It is intended to control the seal strength.

[0005]

In order to achieve the above-mentioned object, the present invention, in the first invention, first comprises a base material layer, an intermediate layer, and a sealant layer, which are sequentially laminated, and an intermediate layer of the base material layer. A packaging material having a printing layer on the contact surface,
It is intended to provide a packaging material having a lamination interface having a peel strength smaller than the peel strength of the printed layer surface.

[0006] The second invention is to provide a packaging material, wherein the sealant layer is an unstretched polypropylene film.

[0007]

As described above, according to the present invention, since this packaging material has a lamination interface having a peel strength smaller than the peel strength of the printing layer surface, a bag is produced by a method such as heat sealing, When the bag is partially held and pulled, the sealed portion of the bag can be easily peeled off and the printing surface is not exposed at the peeling interface.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The packaging material of the present invention will be described below in detail based on one embodiment. The main object of the present invention is to
When, for example, an unstretched polypropylene film (hereinafter abbreviated as CPP) is used for the sealant layer, it becomes difficult to aggregate the sealant layer or to open the sealant at the interface, so that the peel strength between certain layers (layers that cause no problem even if peeled) is improved. The purpose is to improve the unsealing property of the seal portion by appropriately weakening it.
That is, when polyethylene is used as the sealant layer, it can be peeled and opened due to cohesive failure of polyethylene, so that an appropriate opening strength can be obtained. However, the content resistance (CPP is oil resistant, so the content is oily). When used, CPP is used as the sealant layer.), Heat resistance (CPP is superior to polyethylene in heat resistance. When retort packaging, the sealant layer is preferably CPP rather than polyethylene. If polyethylene needs to be used for the sealant layer due to the reason such as polyethylene is not suitable as a material in general, CPP is hard and peeling due to cohesive failure like polyethylene cannot be obtained. For this reason, as a structure of the present invention, opening is facilitated by devising a peeling position between layers as described above. It should be noted that the sealant layer is not limited to CPP, and may be applied as long as it has similar problems such as polyester.

When the printed surface of the base material layer and the intermediate layer are laminated, the peel strength between the base material layer and the intermediate layer may decrease depending on the ink type. Further, if the adhesion of the ink itself to the printing substrate layer is low, the ink may fall off the substrate layer and become dirty, or may be peeled off at the interface between the substrate layer and the printing layer to expose the ink surface. Even if the adhesive strength between the ink surface and the intermediate layer laminated on this ink surface is low, a peeling phenomenon occurs on that surface and the ink surface is exposed. For this reason, for example, the adhesive strength at the interface between the intermediate layer and the sealant layer or at one interlayer interface of the multilayered intermediate layers is set to be weaker than the adhesive strength at the interface between the ink surface and the base material layer or between the ink surface and the intermediate layer. By doing so, the ink surface is not exposed when the packaging material is peeled off. The layer structure of the packaging material of the present invention is, for example, as shown in FIG. 1, an intermediate layer (13) on a base material layer (11) provided with a printing layer (12).
Is provided, and the sealant layer (14) is provided thereon to form a laminated structure.

The base material layer (11) is preferably a plastic film such as a biaxially oriented polypropylene film (hereinafter abbreviated as OPP), a polyester film or a nylon film. Further, the base material layer (11) may be a single layer, or may have a multi-layer structure in which the above-mentioned plastic film, paper, metal foil, etc. are appropriately combined and combined.

A printing layer (1) provided on the substrate layer (11)
In 2), the ink type suitable for the plastic film or the like which is the base material layer to be used may be selected and printed on the base material layer. For example, when OPP is used as the base material layer, an OPP ink containing a urethane resin as a main component is used.

The intermediate layer (13) is located between the base material layer and the sealant layer, for adhering the base material layer and the sealant layer,
Adhesive resin such as polyethylene, polyester film, nylon film and the like are preferably used, which plays a role of improving gas barrier property, and may include a vapor deposition layer such as vapor deposition polyester film of metal such as aluminum. Further, a multi-layer structure in which a polyethylene resin or the like is appropriately combined and composited with the above plastic film may be used.

The sealant layer (14) may be a resin layer having a heat-sealing property, and polypropylene, polyester, polyethylene and the like are preferably used, and a metal vapor-deposited unstretched polypropylene film (hereinafter VM).
A vapor deposition layer such as CPP) may be included.

Using the packaging material (10) thus obtained, a bag making machine which is generally used so that the sealant layer (14) is on the inner surface is used, and a heat seal method is used to form a seal as shown in FIG. The bag is made into a packaging bag. In addition,
The type of the packaging bag is not limited to the pouch seal bag, and may be a pillow bag, a four-sided seal packaging bag, a three-sided seal packaging bag, or any other packaging method.

What is important here is that the peel strength between the layers of the laminated film which is the packaging material; preferably the peel strength at the interface between the intermediate layer and the sealant layer, or at the interlayer interface of one of the multilayered intermediate layers is printed. The peel strength is set to be weaker than the peel strength at the layer surface, that is, the interface between the ink surface and the substrate layer and the interface between the ink surface and the intermediate layer. By doing so, the sealant layers of the packaging material are put together to form a gas-sealing bag by the heat-sealing method, and when the bag is to be unsealed from the sealing part, it can be easily unsealed and the unsealed surface The ink is not exposed on the surface.

Specifically, the difference between the peeling strength on the surface of the printing layer and the peeling strength on the laminated interface having a small peeling strength is 50 gf / 1.
If the width is 5 mm or more, more preferably about 200 gf / 15 mm width, this function can be exhibited. Further, the lower limit of the peel strength at the laminated interface having a small peel strength is 10 gf /
The width is 15 mm or more, more preferably 50 gf / 15 mm or more. If the compatibility between the ink surface and the anchor coating agent applied on the ink surface is poor, the peel strength of the printing layer surface may become extremely small. Specifically, when a urethane-based ink is selected, an anchor coating agent having an isocyanate group that accelerates the curing of the ink is usually used, but it does not react with the urethane-based ink at all and has a wettability. If a butadiene-based or imine-based anchor coating agent having poor performance is selected, the peel strength of the printed layer surface becomes extremely small.

The behavior of each layer when the packaging material of the present invention is made into a bag and the opening operation of the seal portion is performed will be described. That is, when the bag is opened by pinching the seal portion in the direction of the arrow as shown in FIG. 2, first, the sealant layer (14) is broken near the boundary between the sealed portion and the unsealed portion. Next, the intermediate layer (13) and the sealant layer (14) are set to have weaker adhesive strength than the interface between the substrate layer (11) and the printed layer (12) or the interface between the printed layer (12) and the intermediate layer (13). The interface is peeled off and the bag is opened cleanly (see FIG. 3). In this case, the substrate layer (11) and the printing layer (1
Since the interface of 2) or the interface of the printing layer (12) and the intermediate layer (13) has stronger adhesive strength than the interface of the intermediate layer (13) and the sealant layer (14), the interface peels off. The printed layer (12) is not exposed to the outside.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. <Example 1> 20 μm thick OPP as the base material layer (11)
A desired pattern is printed on one side of the sheet using a urethane ink (trade name New LP Super, manufactured by Toyo Ink Mfg. Co., Ltd.) by the gravure printing method in three colors of white, transparent red, and orange, and a printing layer (12 ) Is formed. Next, the surface having the print layer and a metal vapor-deposited 12 μm-thick polyester film (hereinafter abbreviated as VMPET) (manufactured by Toyobo Co., Ltd.) are applied to the print layer surface at a coating amount of 4 to 6 g / m ^2.
Sandwich lamination is performed using a polyethylene (hereinafter abbreviated as PE) resin while applying an isocyanate-based anchor coat (hereinafter abbreviated as AC) agent while adjusting the degree to a certain degree. Finally, the VMPET side of this composite film and the sealant layer (14) 18
A coating amount of 4 to 6 g / μm thick CPP on the VMPET surface
Sandwich lamination is performed using PE resin while applying an isocyanate-based AC agent while adjusting to about m ² , [outer surface] 20 μm thick OPP (11) / printing layer (12) / AC layer (13a) / 13 μm thick PE (13
b) / 12 μm thick VMPET (13c) / AC layer (13
a) / 13 μm thick PE (13b) / 18 μm thick CPP
(14) A packaging material (10a) of the present invention having an [inner surface] structure was produced (see FIG. 4). Here, 20 μm thick OPP
(11) / Printing layer (12) and 18 μm thick CPP (14)
AC layer (13a) / 13 μm thick PE (13
b) / 12 μm thick VMPET (13c) / AC layer (13
a) corresponds to the intermediate layer (13).

Example 2 20 μm which is the base material layer (11)
On the one side of the m-thick OPP, a desired pattern is printed in white and orange using a urethane ink (trade name New LP Super, manufactured by Toyo Ink Mfg. Co., Ltd.) by the gravure printing method.
Print in color to form the print layer (12). Next, the surface on which this printed layer is present and the 25 μm-thick VM with metal vapor deposition.
CPP (manufactured by Toyo Metallizing Co., Ltd.) is applied to the printed layer surface while adjusting the application amount to about 4 to 6 g / m ² while applying an isocyanate type AC agent, and using a PE resin, a sandwich. Lamination is performed, [outer surface] 20 μm thick OPP (11) / printing layer (12) / AC
A packaging material (10b) of the present invention having a layer (13a) / thickness of 13 μm PE (13b) / thickness of 25 μm VMCPP (14) [inner surface] was prepared (see FIG. 5). Here, 20μ
m-thick OPP (11) / printing layer (12) and 25 μm-thick VM
AC layer (13a) / 13μ sandwiched between CPP (14)
The m-thick PE (13b) corresponds to the intermediate layer (13).

<Comparative Example 1> -A typical conventional example. The desired pattern is printed in three colors of transparent red, white and yellow on the one surface of the 20 μm thick OPP which is the base material layer (61) by a gravure printing method, and the printing layer (62) is formed. Let it form. Next, a surface having this printed layer and a metal-deposited 12 μm thick VMPET, a titanium-based AC agent on the printed layer surface, and a butadiene-based AC agent on the surface in contact with the 12 μm-thick VMPET printed layer. While applying each
Sandwich lamination is performed using PE resin. Finally, the VMPET surface of this composite film and the 18 μm-thick CPP that is the sealant layer (64) were treated with VMPE.
Sandwich lamination is performed using PE resin while applying a butadiene-based AC agent on the T surface, [outer surface]
20 μm thick OPP (61) / printing layer (62) / AC layer (63a) / 13 μm thick PE (63b) / AC layer (63
a) / 12 μm thick VMPET (63c) / AC layer (63
a) / 13 μm thick PE (63b) / 18 μm thick CPP
(64) A packaging material (60) of the present invention having an [inner surface] structure was produced (see FIG. 7). Here, the OPP (6
1) / AC layer (63a) sandwiched between printed layer (62) and 18 μm thick CPP (64) / 13 μm thick PE (63b) /
AC layer (63a) / 12 μm thick VMPET (63c) /
The AC layer (63a) / 13 μm thick PE (63b) corresponds to the intermediate layer (63).

In order to evaluate the peeling property of each interlayer interface of the three types of packaging materials produced, the peeling strength of each interlayer interface and the opened state of the bag were measured and checked according to the following measuring methods. The results are shown in Tables 1 and 2. Method of measuring peel strength at each interlayer interface: Peeling speed 300 m
Measured using a Tensilon tensile tester under conditions of m / min and 90 degree peeling. Opening state of the bag: When pinching the vicinity of the center of the bag and opening the bag, observe from which laminated interface of the top seal portion the layer is separated.

[0022]

[Table 1]

[0023]

[Table 2]

From Tables 1 and 2, it can be seen that the packaging material of the present invention has a lamination interface having a peel strength smaller than the peel strength of the printed layer surface. Further, when the bag-made product is opened, the seal portion is peeled off from the laminated interface having no printing surface, and the printing surface is not exposed (Example 1,
2). On the other hand, the packaging material of the conventional example has the smallest peeling strength at the laminated interface having the printed surface, and when the bag-making product is opened, the seal portion is peeled off from the laminated interface having the printed surface and the printed surface is Exposed (Comparative Example 1).

[0025]

[Effect] As described above, since the packaging material of the present invention has a lamination interface having a peel strength smaller than the peel strength of the printing layer surface, when the bag-making product is opened, it is peeled from the lamination interface having no printing surface. However, the printing ink is not exposed and is hygienic. Also, the peeling surface is clean and looks good.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a layer constitution of the present invention in cross section.

FIG. 2 is an explanatory diagram showing an opening state of a bag manufactured using the packaging material of the same example.

FIG. 3 is a partial cross-sectional view of the vicinity of a seal portion of a bag manufactured using the packaging material of the same example.

FIG. 4 is an explanatory view showing another embodiment of the layer structure of the present invention in section.

FIG. 5 is an explanatory view showing another embodiment of the layer structure of the present invention in section.

FIG. 6 is an explanatory view showing a layer structure of a conventional example in a cross section.

FIG. 7 is an explanatory view showing a layer structure of another conventional example in a cross section.

[Explanation of symbols]

 10 ... packaging material 10a ... packaging material 10b ... packaging material 11 ... base material layer 12 ... printing layer 13 ... intermediate layer 13a ... AC layer 13b ... PE 13c ... VMPET 14 ... sealant layer 50 ... packaging material 51 Base material layer 52 Printing layer 53 Adhesive layer 53a AC layer 53b PE 53c VMPET 54 Sealant layer 60 Packaging material 61 Base material layer 62 Printing layer 63 Intermediate Layer 63a AC layer 63b PE 63c VMPET 64 sealant layer

Claims (2)

[Claims] 1. A packaging material in which a base material layer, an intermediate layer, and a sealant layer are sequentially laminated, and a printing layer is provided on the surface of the base material layer that is in contact with the intermediate layer. A packaging material having a lamination interface having a peel strength smaller than the strength. 2. The packaging material according to claim 1, wherein the sealant layer is an unstretched polypropylene film.