JPH10175272A - Laminated self-adhesive label for preventing rupture of bag and method for preventing rupture of bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diffuse internal pressure based on steam at the time of heating and to prevent the destruction of a hermetically sealed container/bag by obtaining a label base material by laminating at least one heat-shrinkable film layer and at least one upper bonding layer. SOLUTION: A label base material is formed by laminating at least one heat-shrinkable film layer and at least one upper bonding layer. The heat- shrinkable film pref. shows a heat shrinkage state of about 70 deg.C and the max. shrinkage factor at 70 deg.C thereof is pref. 20% or more. In the case of food pref. to discharge moisture relatively rapidly, a heat shrinkable material can be used even in the upper bonding film as the function accelerating the heat shrinkability of the heat-shrinkable film. In order to enhance heat skrinkage efficiency, it is proper to use a label material containing a microwave heat generating material, that is, a metal foil layer or a layer containing a metal vapor deposition layer, a coating layer containing a ferroelectric material such as barium titanate or coating layer containing a ferromagnetic material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a label to be attached to a sealed container or bag containing food and a method for preventing destruction.
In particular, the present invention relates to a label for preventing a bag / container from being swollen and broken by steam generated when a food is stored in a sealed container / bag in a microwave oven, and to a destruction prevention method.

[0002]

2. Description of the Related Art When cooking food in a bag or a sealed container made of plastic or paper with a microwave oven, it is convenient if the food can be heated in a sealed packaging container. However, when heated in a microwave oven in a sealed state, the internal pressure of the container increases due to the generation of water vapor due to the heating of the food in the container, the container / bag swells, the container ruptures at unexpected locations, and the contents are spilled. It may stain the range.

[0003] For this reason, a microwave-heat-generating material is used to process a part of a sealed container, or to be attached to a sealed container in the form of a label. There has been proposed a method of providing a water vapor outlet by fusing the part. (Japanese Patent Laid-Open No. 61-
However, in these methods, the microwave heating material generates heat due to the microwave irradiation regardless of the heating state of the food contents. While the heating is not enough, the sealed container is blown out, extra water vapor escapes and the food dries to dryness. For example, it was difficult to adjust the way of releasing water vapor to properly heat the contents.

On the other hand, an attempt has been made to attach a heat-shrinkable label to an opening portion of a bag provided with an opening in advance, thereby causing a small hole in the opening due to shrinkage of the label together with heating to allow water vapor to escape. Of course, if many heat-shrinkable films are combined with various pressure-sensitive adhesives, it is theoretically possible to produce a heat-shrinkable label for preventing bag breakage that meets the intended cooking conditions. The production unit of heat-shrinkable film and the production unit of adhesive processing are much larger in the unit of film production, and when comparing the production unit of adhesive processing with the production unit of adhesive label, It is industrially infeasible to produce a much larger variety of "heat shrink labels" under much larger and desired conditions.

The adhesive strength of a pressure-sensitive adhesive combined with a heat-shrinkable label is 10 to 2 times less than that of a normal product.
It has a swing of about 0% width and has little freedom when selecting adhesive products of different types of adhesive strength, and there is little freedom to obtain an opening under optimal conditions with a combination of adhesive strengths. . For example, the adhesive strength is 1000 g / 25 m
m, the actual value range is 800-1200g / 25m
m and about 600 g / 25 mm for a product having a weak adhesive strength that can be clearly differentiated.

From these points, it can be seen that forming a combination of an individual heat-shrinkable film and an adhesive suitable for each cooking condition is largely contrary to the purpose of supplying an optimal label at low cost.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and is caused by heating when heating and cooking a flexible sealed container in a microwave oven. A sealed container / bag that can be manufactured at a high degree of freedom and at a low cost by preventing the sealed container / bag from being destroyed while dispersing the internal pressure due to water vapor under intended conditions while obtaining favorable heating and cooking conditions. And a bag breaking prevention method.

[0008]

When food is stored in a sealed container or bag and the container or bag is ruptured by heating in a microwave oven, the temperature of the food always rises and the generation of water vapor causes the inside of the container to fail. Since the internal pressure is increasing, if an opening is formed in the container at a constant temperature and an internal pressure, it is possible to obtain a bag breaking prevention measure even under the intended cooking and heating conditions. Therefore, by superimposing another type of label on the surface of the heat-shrinkable label and adjusting the shrinkage of the heat-shrinkable label, it is possible to prepare a label that should appropriately emit water vapor in relation to the material and contents of the container. It has been found that the present invention has been completed.

That is, a first structure of the present invention is an adhesive label comprising a base material layer and an adhesive layer, wherein the label base material has at least one heat-shrinkable film layer and at least one upper adhesive layer. And a laminated adhesive label for preventing bag breakage. Further, the present invention is a laminated pressure-sensitive adhesive label for preventing bag breakage, wherein the heat shrinkage ratio at 70 ° C. of the heat shrinkable film layer is 20% or more.

A second configuration of the present invention is a method for preventing bag breakage for releasing water vapor generated under heating into a sealed container or sealed bag containing food or the like, wherein the label base material has at least one layer of heat. A shrinkable film layer and at least one top-stick layer are laminated, a laminated adhesive label for preventing breakage consisting of a base material layer and an adhesive layer, a cut or an opening previously provided in a sealed container or a sealed bag. This is a method for preventing the breakage of a sealed container / sealed bag, which is characterized by sticking so as to cover. Further, the present invention is a method for preventing the breakage of a sealed container or a sealed bag, wherein the heat shrinkage rate at 70 ° C. of the heat shrinkable film layer of the laminated pressure-sensitive adhesive label for preventing the breakage is 20% or more.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION With regard to an overlaid label to be superimposed on a heat-shrinkable label material having a small degree of freedom, the thickness of a surface base material, strength of a waist, heat generation in a microwave oven,
Adjusts the start of shrinkage of the heat-shrinkable label as the base material layer, depending on the plasticity, heat resistance of the surface base material, the adhesive strength of the adhesive used, the area of the label that protrudes from the base heat-shrinkable label and overlaps, etc. It turns out that you can do it. Hereinafter, embodiments of the invention will be described in detail.

(Heat-shrinkable film) As for the heat-shrinkable film according to the present invention, most materials (PVC, PET, PS, polyolefin, etc.) of commercially available heat-shrinkable films can be used. Since most of the causes of the destruction of the container are water vapor generated from the contents, the heat shrinkable film needs to be heat shrunk at 100 ° C. (boiling point of water).

Preferably, the film shows a clear heat shrinkage state at a temperature of 100 ° C. or less and about 70 ° C. Further, regarding the shrinkage rate which is a factor of the force for obtaining the opening, the maximum heat shrinkage rate at 70 ° C. It is preferably at least 20%.

(Adhesive) The adhesive to be combined with the heat-shrinkable film can be freely selected from the viewpoint of the adhesive strength as described above, and an acrylic solvent type, an acrylic emulsion type, a rubber solution type or the like is used. it can. However, an adhesive showing stable performance even at a temperature around 100 ° C. with respect to heating in a microwave oven is desirable, and an acrylic cross-linking adhesive is particularly preferred. In addition, as a material of a commonly used sealed container or sealed bag, there are many polyolefin-based materials such as PE and PP, and the difference in the adhesive strength of the adhesive to these nonpolar materials depends on the type of the adhesive. Therefore,
Than the choice of adhesive, since the condition range is easily changed by the characteristics of the top-stick label to be overlaid, within the conditions such as the workability of automatic sticking of the label and the range that prevents leakage of the contents,
Those having low adhesive strength are preferred.

(Top Label) In the case of a food product which preferably releases water relatively early, a function of promoting the heat shrinkage of the heat shrinkable film (label) as the base material layer is also applied to the top label. Heat shrinkable materials can be used. As an example, lamination of soft PVC on a PET substrate layer is possible.

In order to improve the efficiency of heat shrinkage, the overcoating layer contains a microwave heat-generating material, that is, a layer including a metal foil layer or a metal deposition layer, or a ferroelectric such as barium titanate. It is appropriate to use a label material containing a coating layer such as ink or a coating layer containing a ferromagnetic material.In the label industry, there are many adhesive products made of aluminum-coated polyester film. I can do it.

[0017] In the case of foods which need to keep a relatively sufficient amount of water, such as steaming, the function of delaying (suppressing) the heat shrinkage of the heat shrinkable film label as the base material layer is as follows.
A material that suppresses the heat shrinkage of the base material layer can be used for the upper label. As an example, on a heat-shrinkable PET substrate layer, 1
At 00 ° C., a PET film having no heat shrinkage can be laminated via an adhesive. In this case, the degree of suppression can be adjusted by changing the thickness of the PET film to be laminated as the upper adhesive layer.

Further, for fine adjustment, a material having an accelerating effect and a material having an inhibiting effect can be laminated. Further, the relative size of the top-adhesive label with respect to the base material layer is also effective for delicate preparation. However, it is not preferable to use stiff paper, film, or the like that completely inhibits the heat shrinkage of the base layer.

(Adhesive for Overlying Label) The adhesive to be combined with the overlying film can be freely selected from the viewpoint of the adhesive strength as described above, as in the case of the heat-shrinkable film as the substrate layer. Acrylic solvent type, acrylic emulsion type, rubber type solution type, etc. can be used. However, an adhesive showing stable performance even at a temperature around 100 ° C. with respect to heating in a microwave oven is desirable, and an acrylic cross-linking adhesive is particularly preferred. In addition, since it is necessary to change the shrinkage condition of the heat-shrinkable label as the base material layer depending on the characteristics of the top-adhesive label, a material having a high adhesive strength in sticking to the base material layer is preferable.

(Label laminating method) The present invention is intended to solve the delicate heat shrinkage of a label by laminating a plurality of materials instead of a single material. Overlaying another type of adhesive label on a label can be easily created within the common sense of the labeling industry and the label making industry. For example, there is a method in which a heat shrinkable label serving as a base is attached to an adherend using two label attaching machines (also referred to as labelers), and another type of adhesive label is attached using another label attaching machine. This method is advantageous when adjusting the conditions under which the label is peeled off by extruding the top-adhesive label overlaid on the heat-shrinkable label serving as the base under various conditions.

Prior to label production, a heat-shrinkable label material and another kind of adhesive label material are overlapped (over lamination method usually called in the label printing industry), and then punched into a label shape to obtain a laminated label. Then, you may stick on a to-be-adhered body with a label sticking machine.

Further, if a label pasting machine is incorporated in a label printing machine, more complicated processing becomes possible, and a state in which another type of top-sticking label is overlapped only at the center of the heat-shrinkable label becomes possible. Also, after punching out only the heat-shrinkable label, over-laminate another type of top-sided adhesive label material and create a label punched into a label shape in which another type of top-sided adhesive label is larger than the heat-shrinkable label. Also, there is a method of overlaminating a different type of overlying label only on half of the punched heat-shrinkable label and then punching out the same to produce a heat-shrinkable label that is overlapped only by half. However, the method of producing the bag-break preventing label is not limited to those described here, and it goes without saying that various ordinary production methods in the label printing industry and the label pasting industry can be used.

Of course, it is possible to print various characters and graphics on the surface of the label and use it as a means for transmitting information.
As long as it is a label material for printing, it is natural,
Needless to say, it is also possible to add an easy peel function by utilizing the adhesiveness of the upper label.

(Method for Preventing Bag Breaking) To apply a bag breaking preventing label in bag breaking prevention, it is necessary to provide a cut or opening in the target container in advance. In this processing, it is necessary that the label be processed before the label is attached and a label large enough to cover the cut or opening. The condition of the water vapor release can be slightly changed depending on the size of the notch or the opening and the size of the label, so that the method of making the notch, the size and the position, the shape and the size and the position of the opening, etc. Can be investigated in advance by experiments to determine the optimum conditions for the individual foods as contents.

The material used for the sealed container / bag is PE,
Other than olefin resin such as PP, PET / CPP, PET
/ PE, nylon / CPP and other composite films, and those containing a metal foil such as an aluminum foil between them.

Regarding the shape of the notch or opening for vapor release, any shape may be used as long as the function of releasing water vapor, the ease of processing, and the ease of sealing with a label are satisfied. Well-known processing shapes such as a U-shape, a Λ-shape, and a T-shape are used in addition to the X-shape tested in the embodiment.

[0027]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

[Preparation of Heat Shrinkable Label and Measurement of Heat Shrinkage] PET of various thicknesses commercially available as a heat shrinkable film
(Polyethylene terephthalate) film and PVC (polyvinyl chloride) film were used, and various pressure-sensitive adhesives manufactured by Dainippon Ink and Chemicals, Inc. were used as pressure-sensitive adhesives according to the degree of adhesion as shown in Table 1. The amount of the adhesive applied was 25 ± 2 μm. The heat shrinkage of the film is 10cm ×
The film cut into a size of 10 cm is set at each set temperature (7
(0 ± 2, 100 ± 2, 140 ± 2 ° C.) for 5 minutes and then measured by measuring the length and width. The adhesive strength of the pressure-sensitive adhesive was 60
It was determined as the peel resistance after one minute. The unit is (g / 25mm)
It is. Table 1 shows the results.

[0029]

[Table 1]

Various symbols in Table 1 represent the following. FNC: Acrylic cross-linkable solution type (removable with low adhesion) AER: Acrylic cross-linked solution type (removable with very low adhesive strength) A2: Acrylic non-crosslinked emulsion type (removable medium adhesive) ) Adhesive FL: Acrylic cross-linking solution type (general strong adhesion type)
Adhesive FYN: Acrylic cross-linkable solution type (medium adhesive strength re-peelable) adhesive All of the above are adhesives manufactured by Dainippon Ink and Chemicals, Inc. Yupo: PP synthetic paper manufactured by Oji Oil Chemicals Co., Ltd. (-): The indication of (-) in the shrinkage ratio indicates that the film is extended.

[Examples 1 to 7 and Comparative Examples 1 and 2] As a sealed bag for food, the size of the storage portion of the contents was 120 m in length.
A sealed bag with a zipper made of nylon / polyethylene having a size of mx 180 mm in width (the label-attached surface is a nylon surface) was prepared. An X-shaped cut having a length of 10 mm × 10 mm was made in the center of this one side.
The various labels shown in Table 3 were attached. 100cc of water in the bag
And insert it into a microwave (RE-20, manufactured by Sharp Corporation).
0, high frequency output; 960 W). The water in the bag was heated, and the generated water vapor caused the bag to expand, the label began to shrink, and the time until the release of water vapor from the cut portion without breaking the bag was measured. In the present invention, the upper adhesive layer is laminated in order to control the degree of shrinkage and peeling of the label. For comparison, the time until the release of water vapor was measured for each heat-shrinkable label alone before lamination. Table 2 shows the evaluation results.

[0032]

[Table 2]

In the peeling accelerating treatment shown in Table 2, * Aluminum deposition: as an upper layer, aluminum deposited thickness 2
A label in which the pressure-sensitive adhesive FL was applied to a thickness of 25 μ on PET of 5 μ was used. * Overlapping: The heat-shrinkable labels shown in Table 1 were laminated. * Flexible PVC: 100 μm of PVC shown in (g) of Table 1 was laminated. The adhesive is A from Nippon Ink and Chemicals, Inc.
2. A film thickness of 25 μm was used.

In the peeling delay treatment shown in Table 2, * PET12: PET film, thickness 12μ * PET25: PET film, thickness 25μ * PET50: PET film, thickness 50μ A FL type manufactured by Kogyo Co., Ltd. was used, and the film thickness was 25 μm.

Examples 8 to 15 A heat-shrinkable label obtained by coating a weakly-adhesive type adhesive, FNC (manufactured by Dainippon Ink and Chemicals, Inc.), on a 30 μm thick PET film to 25 μm (corresponding to b in Table 1). Based on the above, the contribution of the adhesive force of the pressure-sensitive adhesive for the over-label to the peeling delay treatment was examined. The size of the base heat-shrinkable label (corresponding to b in Table 1) was set to 25 mm × 25 mm as shown in FIG. 1, and the upper adhesive label was evaluated in various sizes as shown in FIG. The evaluation results are shown in Tables 3 and 4.

[0036]

[Table 3]

[0037]

[Table 4]

"FTN" in Tables 3 and 4 is an acrylic cross-linking type (solution type) manufactured by Dainippon Ink and Chemicals, Inc.
The adhesive for re-peeling low adhesive strength is shown.

[Examples 16 to 19 and Comparative Examples 3 to 4] 3
Based on a heat-shrinkable label (corresponding to b in Table 1) in which a weak adhesive type FNC manufactured by Dainippon Ink and Chemicals Co., Ltd., which is a weakly-adhesive type adhesive, is applied to a 0μ-thick PET film at a thickness of 25μ The contribution to the peeling promotion or delay treatment by the method was examined. Furthermore, the effect of laminating a plurality of overlying layers was also studied. The size of the heat-shrinkable label of the base (corresponding to b in Table 1) was 25 mm × 25 mm as shown in FIG. 1, and the upper pasted label was evaluated at the same size as Type 1 in FIG. Table 5 shows the evaluation results.

[0040]

[Table 5]

In Example 18 in Table 5, the adhesive "A2" was applied to a 100 μm thick flexible PVC for the heat-shrinkable base material layer.
Shows that an upper adhesive layer having a thickness of 25 μm is coated with an upper adhesive layer having a thickness of 25 μm and a pressure-sensitive adhesive FL applied to a 25 μm thick PET. Similarly, in Example 19, a 25 μm thick PE
This shows that an upper adhesive layer in which an adhesive “A2” is applied to T with a thickness of 25 μ is laminated on an upper adhesive layer in which an adhesive FL is applied to a thickness of 25 μ with PET deposited on aluminum and has a thickness of 25 μ. . Fine papers <55> and <70> represent fine papers having a basis weight of 55 kg and 70 kg, respectively.

[0042]

According to the present invention, when the flexible adhesive container is heated and cooked in a microwave oven by using the laminated pressure-sensitive adhesive label and the method for preventing bag breakage obtained according to the present invention, the internal pressure due to water vapor generated by heating is controlled under the intended conditions. It can be dissipated below. In other words, food containers that require a crisp texture have an earlier release of water vapor, while foods that have a moist texture have a lower release of water vapor, etc. It is possible to obtain a bag breaking prevention label that prevents breakage. Furthermore, using these labels, it is possible to obtain a method for preventing bag breakage when a sealed container or sealed bag is heated in a microwave oven.

[Brief description of the drawings]

FIG. 1 is a diagram showing the shape of various top-attached labels, the shape of heat-shrinkable labels, and the shapes and positions of cuts.

[Explanation of symbols]

 1 Label on top (solid line) 2 Heat shrink label (dotted line) 3 Notch shape (x shape)

Claims (4)

[Claims] 1. A pressure-sensitive adhesive label comprising a base material layer and a pressure-sensitive adhesive layer, wherein the label base material has at least one heat-shrinkable film layer and at least one overlying layer laminated on each other. Laminated adhesive label for bag prevention. 2. The laminated pressure-sensitive adhesive label according to claim 1, wherein the heat-shrinkable film layer has a heat-shrinkage rate at 70 ° C. of 20% or more. 3. A bag breaking prevention method for releasing water vapor generated under heating into a sealed container or a sealed bag containing food or the like, wherein the label base material comprises at least one heat-shrinkable film layer and at least one heat-shrinkable film layer. The upper adhesive layer is laminated, the laminated adhesive label for preventing breakage consisting of the base material layer and the adhesive layer is attached so as to cover the cut or opening provided in the sealed container / sealed bag in advance. A method for preventing the breakage of sealed containers and sealed bags. 4. The method for preventing bag breaking according to claim 3, wherein the heat shrinkage rate of the heat shrinkable film layer of the laminated pressure-sensitive adhesive label for preventing bag breaking at 70 ° C. is 20% or more.