Labels, packaging materials and packages

Abstract

To provide a label or the like capable of advancing timing of discharging steam or the like generated from contents of a packaging container heated by a microwave oven.SOLUTION: A label includes: a substrate layer having a heat-shrinkable film 6 that shrinks when heated; and an adhesive layer 7 formed on one side of the substrate layer, wherein the adhesive layer 7 absorbs microwaves, and contains low volatility oil to be heated.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to packaging bodies such as packaging containers and packaging bags for packaging foods and the like to be heated using a microwave oven or the like, packaging materials constituting the packaging bodies such as lids and packaging films, and labels to be affixed to the packaging materials. [Background technology]

[0002] 2. Description of the Related Art Many foods are sold in which the contents of various ingredients or processed foods are sealed in a packaging bag made of packaging film or the opening of a packaging container containing the contents is sealed with packaging film or the like so that the foods can be cooked directly in a microwave oven.

[0003] If this type of food is cooked directly in a microwave oven, the internal pressure of the packaging bag or container will rise excessively due to water vapor and other factors generated by the contents, causing the packaging film that makes up the packaging bag or the packaging film that seals the opening of the packaging container to burst, causing the contents to be scattered to the outside.

[0004] For this reason, various techniques have been proposed to naturally form steam vent holes in the bag surface or the lid of the container when heated.

[0005] For example, Patent Document 1 discloses a technology in which a label having a heat-shrinkable film is attached so as to cover a steam vent formed on the lid of a container; when the container is heated in a microwave oven, the heat-shrinkable film shrinks due to the heat, opening the steam vent, and allowing water vapor and the like generated inside the container to be released to the outside. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-7703 A Summary of the Invention [Problem to be solved by the invention]

[0007] When a container containing food is heated in a microwave oven, various technologies have been proposed for opening a steam vent to release water vapor and other substances generated by the food. However, depending on the application, it may be desirable to release water vapor and other substances as soon as possible after heating in the microwave oven begins.

[0008] The present invention has been made in light of the above-mentioned circumstances, and aims to provide a label, packaging material, and package that are capable of releasing water vapor and the like quickly after heating in a microwave oven or the like begins. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention is configured as follows.

[0010] (1) The label of the present invention is a label comprising a base layer having a heat-shrinkable film that shrinks when heated, and an adhesive layer formed on one side of the base layer, wherein the adhesive layer contains a low-volatility oil.

[0011] The label of the present invention is attached, for example, to a packaging material constituting a packaging container or packaging bag containing contents such as various ingredients or processed foods, so as to cover the steam vent portion. When the packaging container or packaging bag containing the contents is heated using a microwave oven or the like, the heat-shrinkable film in the base layer of the label shrinks due to the heat, opening the steam vent portion of the packaging material and allowing water vapor and the like generated from the contents to be released outside the label.

[0012] In the label according to the present invention, the adhesive layer on one side of the base layer having the heat-shrinkable film contains a low-volatility oil. This low-volatility oil is heated by absorbing microwaves from a microwave oven or the like, and the temperature rise of the adhesive layer due to microwave heating is higher than that of an adhesive layer not containing the low-volatility oil. This temperature rise of the adhesive layer promotes heating of the heat-shrinkable film of the base layer, and the heat-shrinkable film can be shrunk early after heating in a microwave oven or the like is started.

[0013] As a result, when the packaging container or packaging bag is heated using a microwave oven or the like, the heat-shrinkable film of the base material layer of the label can be heat-shrunk early, opening the steam vent formed in the packaging material that makes up the packaging container or packaging bag, allowing water vapor and the like generated from the contents to be released early.

[0014] (2) According to one embodiment of the present invention, the low volatility oil is a polyol.

[0015] According to this embodiment, the polyol contained in the adhesive layer on one side of the base layer having a heat-shrinkable film is heated by absorbing microwaves from a microwave oven or the like. Therefore, when microwave heating is performed in a microwave oven or the like in comparison with an adhesive layer that does not contain a polyol, the adhesive layer rises in temperature due to heating more rapidly, accelerating heating of the heat-shrinkable film of the base layer, and allowing the heat-shrinkable film to heat shrink soon after heating in a microwave oven or the like begins.

[0016] (3) In another embodiment of the present invention, the low volatility oil is a vegetable oil.

[0017] According to this embodiment, the vegetable oil contained in the adhesive layer on one side of the base layer having a heat-shrinkable film is heated by absorbing microwaves from a microwave oven or the like. Therefore, when microwave heating is performed in a microwave oven or the like, the adhesive layer rises in temperature due to heating more rapidly than an adhesive layer that does not contain vegetable oil, accelerating heating of the heat-shrinkable film of the base layer, and allowing the heat-shrinkable film to heat-shrunk soon after heating in a microwave oven or the like begins.

[0018] (4) In a preferred embodiment of the present invention, the polyol is glycerin.

[0019] In this embodiment, the glycerin contained in the adhesive layer on one side of the base layer absorbs microwaves from a microwave oven or the like and is heated. Therefore, when subjected to microwave heating in a microwave oven or the like, the temperature rise of the adhesive layer due to heating is higher than that of an adhesive layer that does not contain glycerin, which promotes heating of the heat-shrinkable film of the base layer and allows the heat-shrinkable film to heat-shrunk soon after heating in a microwave oven or the like begins.

[0020] (5) In one embodiment of the present invention, the content of the glycerin in the pressure-sensitive adhesive layer is 15% by weight or more and 60% by weight or less on a dry weight basis.

[0021] According to this embodiment, the glycerin content in the adhesive layer is 15% by weight or more on a dry weight basis, so that when subjected to microwave heating in a microwave oven or the like, the temperature of the adhesive layer can be raised to a level capable of promoting heating of the heat-shrinkable film of the base layer, while the glycerin content is 60% by weight or less on a dry weight basis, so that the adhesive strength of the adhesive layer can be sufficiently ensured.

[0022] (6) In another embodiment of the present invention, the pressure-sensitive adhesive layer is a water-based pressure-sensitive adhesive layer.

[0023] According to this embodiment, the adhesive layer is a water-based adhesive layer, which is suitable for food applications.

[0024] (7) In one embodiment of the present invention, the base layer is made of the heat-shrinkable film, and the pressure-sensitive adhesive layer is formed on one side of the heat-shrinkable film.

[0025] According to this embodiment, since an adhesive layer is formed on one side of the heat-shrinkable film, when the film is heated in a microwave oven or the like, the heat-shrinkable film is efficiently heated due to the temperature rise of the adhesive layer.

[0026] (8) The packaging material of the present invention is a packaging material having a steam vent for discharging steam generated by heating, and any one of the labels (1) to (7) above is affixed so as to cover the steam vent.

[0027] According to the packaging material of the present invention, when the packaging material is used to form a packaging container or bag containing contents such as various ingredients or processed foods, when the packaging container or bag containing the contents is heated in a microwave oven, the heat-shrinkable film of the label covering the steam vent portion of the packaging material heat-shrinks early after heating begins, opening the steam vent portion of the packaging material and enabling water vapor and the like generated from the contents to be released early.

[0028] (9) In another embodiment of the present invention, the packaging material forms a lid that closes an opening of a container body that contains the contents.

[0029] According to this embodiment, when the packaging container is heated using a microwave oven or the like, the internal pressure of the packaging container is prevented from increasing excessively due to water vapor generated from the contents, etc., and the lid body is prevented from coming off the container body of the packaging container.

[0030] (10) A package according to the present invention comprises the packaging material according to (9) above and the container body for accommodating contents.

[0031] According to the packaging body of the present invention, when the packaging container which is the packaging body is heated using a microwave oven or the like, the internal pressure of the packaging container is prevented from increasing excessively due to water vapor generated from the contents, etc., and the lid body is prevented from coming off the container body. Effect of the Invention

[0032] According to the present invention, the adhesive layer on one side of the base layer of the label contains a low-volatile oil that is heated by absorbing microwaves from a microwave oven or the like. Therefore, compared to an adhesive layer that does not contain this, the temperature rise due to microwave heating is higher, which can promote heating of the heat-shrinkable film on the base layer and enable the heat-shrinkable film to shrink quickly after heating in a microwave oven or the like begins.

[0033] As a result, when the packaging container or packaging bag is heated using a microwave oven or the like, the heat-shrinkable film of the base material layer of the label can be heat-shrunk early, opening the steam vent formed in the packaging material that makes up the packaging container or packaging bag, allowing water vapor and the like generated from the contents to be released early. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a plan view of a packaging container according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0036] FIG. 1 is a plan view of a packaging container 1 as a packaging body according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG.

[0037] The packaging container 1 of this embodiment comprises a container body 2 containing contents (not shown), such as microwave cooked food, a top sealing film 4 as packaging material that seals the upper opening 3 of the container body 2, and a label 5 affixed to the top sealing film 4.

[0038] The container body 2 is provided with a brim-shaped flange portion 2a around the upper opening 3, and a top seal film 4 is heat-sealed to the upper surface of this flange portion 2a to form a hermetic seal.

[0039] In this embodiment, in order to prevent the packaging container 1 from bursting due to steam generated when the packaging container 1 is heated in a microwave oven as is, one corner of the upper surface of the top sealing film 4, which is rectangular when viewed from above, is printed with a notation (not shown) encouraging the user to peel off the top sealing film 4, as shown by the arrow C, to the position indicated by the dashed line B, as shown in FIG. 1.

[0040] That is, in this packaging container 1, a consumer who purchases the packaged product peels off one corner of the top sealing film 4 to form a steam release hole, and then heats the packaging container 1 in a microwave oven.

[0041] However, if a consumer inadvertently forgets to peel off the corner of the top sealing film 4 and heats the packaging container 1 in a microwave oven, the packaging container 1 will burst.

[0042] For this reason, the packaging container 1 of this embodiment is configured as follows to allow the generated water vapor, etc. to be discharged even if the packaging container 1 is heated in a microwave oven without peeling off the corners of the top sealing film 4, and to prevent the packaging container 1 from bursting.

[0043] In the center of the top sealing film 4, a steam vent hole 4a that is circular in plan view is formed as a steam vent section for discharging steam generated when the top sealing film 4 is heated in a microwave oven without peeling off the corners of the top sealing film 4.

[0044] A label 5 is attached to the top seal film 4 so as to cover the steam release hole 4a.

[0045] The label 5 includes a heat-shrinkable film 6 that forms a base layer and shrinks when heated, and an adhesive layer 7 formed on one side of the heat-shrinkable film 6 .

[0046] The heat-shrinkable film 6 is a shrink film that shrinks when heated. This heat-shrinkable film 6 is, for example, a uniaxially oriented polystyrene film (OPS), and in this embodiment, has a rectangular shape when viewed from above.

[0047] This heat-shrinkable film 6 is not limited to uniaxially oriented polystyrene film, but may be, for example, a heat-shrinkable PET film, a heat-shrinkable PE (polyethylene) film, a heat-shrinkable PP (polypropylene) film, a heat-shrinkable PV (polyvinyl chloride) film, or a hybrid heat-shrinkable film that is a laminate of PS (polystyrene) and PET (polyethylene terephthalate), and may be a biaxially oriented heat-shrinkable film instead of a uniaxially oriented film.

[0048] The container body 2 and the top seal film 4 are made of a synthetic resin such as polypropylene, polyethylene, or polyethylene terephthalate.

[0049] If a consumer who has purchased the packaged product forgets to peel off one corner of the top sealing film 4 and heats the packaging container 1 in a microwave oven as is, the heat shrinkable film 6 of the label 5 will shrink due to heating, and furthermore, because the corner of the top sealing film 4 has not been peeled off, the heat shrinkable film 6 will be distorted and wrinkled together with the adhesive layer 7 due to an increase in internal pressure caused by steam and the like generated from the contents of the container body 2, or the heat shrinkable film 6 will be partially peeled off. As a result, a partial gap will be generated between the top sealing film 4 and the adhesive layer 7 of the label 5, and the central steam vent hole 4a of the top sealing film 4 will be partially connected to the space outside the label 5, and the steam and the like generated from the contents of the container body 2 will be discharged outside the label 5, preventing the packaging container 1 from bursting.

[0050] If a consumer heats the packaging container 1 in a microwave oven without peeling off one corner of the top seal film 4, the internal pressure will rise rapidly due to steam generated from the contents of the container body 2a. Therefore, in order to prevent the packaging container 1 from bursting, it is necessary to release the steam generated from the contents of the container body 2 to the outside of the label 5 as soon as possible after the start of heating in the microwave oven.

[0051] Therefore, in the packaging container 1 of this embodiment, the heat-shrinkable film 6 of the label 5 is adapted to shrink and deform quickly after heating in a microwave oven is started.

[0052] Specifically, the adhesive layer 7 formed on one side of the heat-shrinkable film 6 contains a low-volatility oil that is heated by absorbing microwaves from a microwave oven.

[0053] Low volatility oils include, for example, polyols and vegetable oils.

[0054] As the polyol, for example, glycerin is preferable.

[0055] A preferred vegetable oil is, for example, olive oil.

[0056] In this embodiment, the adhesive layer 7 contains glycerin, which is a polyol.

[0057] The adhesive constituting the adhesive layer 7 is preferably a water-based adhesive in which a polymer is emulsified and dispersed in water, and in this embodiment, is an acrylic adhesive.

[0058] By thus incorporating glycerin, which absorbs microwaves and is heated, in the adhesive layer 7 formed on one side of the heat-shrinkable film 6, when the packaging container 1 is heated in a microwave oven, the glycerin in the adhesive layer 7 absorbs the microwaves from the microwave oven and is heated. This causes a higher temperature rise in the adhesive layer 7 than when glycerin is not contained, accelerating the heating of the heat-shrinkable film 6 on one side of which the adhesive layer 7 is formed, and the heat-shrinkable film 6 is heat-shrunk early. This heat-shrinkage of the heat-shrinkable film 6 causes the central steam vent hole 4a of the top seal film 4 to partially communicate with the space outside the label 5, allowing water vapor and the like generated from the contents of the container body 2 to be released early after heating begins.

[0059] Therefore, even if the packaging container 1 is heated in a microwave oven without peeling off one corner of the top sealing film 4 and the internal pressure increases suddenly due to water vapor or the like generated from the contents of the container body 2, the heat-shrinkable film 6 can be heated and heat-shrunk quickly, so that the water vapor or the like generated from the contents of the container body 2 can be released quickly, and the packaging container 1 can be prevented from bursting.

[0060] As described above, in this embodiment, the pressure-sensitive adhesive layer 7 contains glycerin that is heated by absorbing microwaves, and the content of this glycerin was examined as follows.

[0061] First, six types of samples, No. 1 to No. 6, having different glycerin contents in the adhesive layer 7 and the compositions shown in Table 1 below were prepared.

[0062] [Table 1] Table 1 shows the weight percentage of the dry weight of the acrylic adhesive and glycerin that constitute the adhesive layer 7.

[0063] In Table 1, No. 1 is a sample containing only an acrylic adhesive without glycerin, and No. 2 to No. 6 are samples containing glycerin at weight percentages of 15 wt%, 30 wt%, 50 wt%, 60 wt%, and 70 wt%, respectively.

[0064] Among these, sample No. 6 containing 70% by weight of glycerin exhibited poor adhesion and was not usable due to insufficient adhesive strength as the adhesive layer 7.

[0065] Therefore, in order to ensure the adhesive strength required for the adhesive layer 7, the content of glycerin must be less than 70% by weight, and is preferably 60% by weight or less.

[0066] Each label made of a heat-shrinkable film having an adhesive layer formed on one side of each of the five samples (No. 1 to No. 5, excluding No. 6, which had insufficient adhesive strength) was attached to a PET film having a thickness of 50 μm. The PET film with each label attached was heated in a microwave oven at an output of 500 W for 3 minutes. The surface temperature of each label before and after heating in the microwave oven was measured using a non-contact thermometer.

[0067] The results are shown in Table 2 below.

[0068] [Table 2] As shown in Table 2, the temperature rise upon heating of label No. 1, which was attached to a PET film with an adhesive layer that did not contain glycerin, was 36.0°C, while the temperature rise upon heating of labels No. 2 and No. 3, which were attached to a PET film with adhesive layers containing 15% and 30% by weight of glycerin, respectively, was 40.8°C and 40.9°C, both of which were more than 4.5°C higher than label No. 1.

[0069] In addition, the temperature rise upon heating of labels No. 4 and No. 5, which were attached to PET film with adhesive layers containing 50% and 60% by weight of glycerin, was 42.2°C and 45.1°C, respectively, indicating that the higher the glycerin content, the higher the temperature rise upon heating.

[0070] By incorporating glycerin, which absorbs microwaves and heats up, into the adhesive layer, the temperature rise caused by heating the label can be increased compared to when glycerin is not incorporated. This temperature rise can be increased by 4.5°C or more, so it is preferable to set the glycerin content to 15% by weight or more.

[0071] Next, the heat shrinkage state of the label on the top seal film was visually observed. That is, each label made of each heat shrinkable film having an adhesive layer formed on one side thereof from the five types of samples No. 1 to No. 5 in Table 1 above was attached to one sheet of top seal film. A container containing 100 g of water as the content was sealed with this top seal film, and heated in a microwave oven at an output of 500 W for 2 minutes, and then the degree of heat shrinkage of each label on the top seal film was visually evaluated. The 2 minutes was the time until the water in the container started to boil.

[0072] The evaluation results are shown in Table 3 below.

[0073] [Table 3] As shown in Table 3, label No. 1, which was attached to the top seal film with an adhesive layer that did not contain glycerin and was heated by absorbing microwaves, did not shrink due to heating, whereas labels No. 2 and No. 3, which were attached to the top seal film with adhesive layers containing 15% and 30% by weight of glycerin, respectively, shrank due to heating and wrinkles occurred.

[0074] Furthermore, labels No. 4 and No. 5, which were attached to a top seal film using adhesive layers containing 50% and 60% by weight of glycerin, respectively, showed significant shrinkage due to heating and significant wrinkles were observed.

[0075] In order to allow a label made of a heat-shrinkable film to sufficiently heat shrink soon after the start of heating, the glycerin content is preferably 50% by weight or more, and more preferably 60% by weight or more.

[0076] As described above, the higher the glycerin content, the greater the thermal shrinkage of the heat-shrinkable film of the label, resulting in significant wrinkles. This is because the glycerin absorbs microwaves and generates heat, causing the temperature of the adhesive layer to rise higher, accelerating the heating of the heat-shrinkable film and reducing the cohesive strength of the adhesive layer, making it easier for the label to peel off from the top seal film.

[0077] As described above, according to this embodiment, the adhesive layer 7 formed on one side of the heat-shrinkable film 6 constituting the label 5 contains glycerin that is heated by absorbing microwaves from a microwave oven. Therefore, if a consumer does not peel off one corner of the top-sealing film 4 of the packaging container 1 and heats it in a microwave oven, the glycerin in the adhesive layer 7 absorbs microwaves and heats up, causing the temperature rise of the adhesive layer 7 to increase. This promotes heating of the heat-shrinkable film 6 on one side of which the adhesive layer 7 is formed, causing early thermal shrinkage from the start of heating, opening the steam vent hole 4a of the top-sealing film 4, and allowing water vapor and the like generated from the contents of the packaging container 1 to be released early. This prevents the packaging container 1 from bursting even if the consumer does not peel off one corner of the top-sealing film 4 and the internal pressure due to water vapor and the like generated from the contents rises suddenly.

[0078] In the above embodiment, the label of the present invention is described as being applied to a packaging container that is heated in a microwave oven after the consumer peels off a portion of the top sealing film 4 of the packaging container 1 to form a steam release hole, but the label of the present invention may also be applied to a packaging container that does not require the consumer to form a steam release hole before heating in a microwave oven.

[0079] Although the base layer of the label in the above embodiment is composed of only a heat shrinkable film, the base layer may be composed of a laminate film of a heat shrinkable film and another film.

[0080] In the above embodiment, the upper opening 3 of the container body 2 is sealed with the top sealing film 4, but in another embodiment, it may be sealed with a plate-shaped lid instead of the top sealing film 4. In this case, a steam release part is formed in the lid, and a label is attached so as to cover this steam release part.

[0081] The present invention may also be applied to, for example, a packaging bag formed by overlapping packaging films and heat-sealing the peripheral portion thereof, without being limited to the packaging container 1. In this case, a steam release portion may be formed in the packaging bag, and a label may be attached so as to cover the steam release portion. [Explanation of symbols]

[0082] 1 Packaging container 2 Container body 3 Top opening 4 Top seal film 4a Steam vent hole 5. Labels 6. Heat-shrinkable film 7 Adhesive layer

Claims

1. A base layer having a heat-shrinkable film that shrinks when heated, and a A label comprising an adhesive layer, The pressure-sensitive adhesive layer contains a low-volatile oil, The low volatility oil is a vegetable oil, The pressure-sensitive adhesive layer is an aqueous pressure-sensitive adhesive layer. A label characterized by:

2. the base layer is made of the heat-shrinkable film, and the pressure-sensitive adhesive layer is formed on one surface of the heat-shrinkable film; The label of claim 1.

3. A packaging material having a steam vent for discharging steam generated by heating, The label according to claim 1 or 2 is attached so as to cover the steam release portion. A packaging material characterized by:

4. The packaging material constitutes a lid that closes an opening of a container body that contains contents. The packaging material according to claim 3.

5. The packaging material according to claim 4 and the container body for accommodating contents. A package comprising:

Images