Easy-to-peel tape, wound body, and packaging bag for heating

Abstract

The present invention provides: an easy-to-peel tape in which winding deviation or winding collapse does not easily occur when wound, and winding deviation can be easily corrected even if winding deviation occurs; a wound body thereof; and a packaging bag for heating in which the easy-to-peel tape is used. An easy-to-peel tape according to the present invention is composed of a laminate having a base material layer and an easy-to-peel layer, and the surface friction coefficient of the front surface of the laminate and the rear surface of the laminate at 23°C is 0.2-2.0. A wound body according to the present invention is obtained by winding the easy-to-peel tape. A packaging bag for heating according to the present invention is for heating contents, and has a steam-passing part for passing steam when the contents are heated and the internal pressure increases. The steam-passing part includes: two sheets of film; and the easy-to-peel tape of the present invention inserted between the two sheets of film.

Description

Peelable tape, wound body, and packaging bag for heat treatment

[0001] The present invention relates to a peelable tape, a wound body, and a packaging bag for heat treatment.

[0002] Conventionally, there has been provided on the market a packaged food in which foods such as cooked or semi-cooked foods are filled in a heat-resistant plastic packaging bag and heat-cooked by a microwave oven immediately before eating. However, when such a packaged food is heated by a microwave oven, there are drawbacks that the internal pressure increases due to the thermal expansion of the water vapor and internal air inside the packaging bag, causing the packaging bag to burst and the contents to scatter, or contaminating the inside of the microwave oven.

[0003] Before microwave cooking, a method has been adopted to prevent the packaging bag from bursting by previously making small holes in the packaging bag to suppress the increase in internal pressure. However, in this method, the generated water vapor is immediately released outside the packaging bag, not only reducing the steaming effect due to the water vapor, but also causing the drying of the food inside the packaging bag to progress and deteriorating the taste. Therefore, a packaging bag having a steam vent seal part (vent part) that vents steam to release pressure when the internal pressure of the packaging bag increases is known (for example, Patent Document 1). In Patent Document 1, by sandwiching a peelable tape (peelable tape) between films, when an internal pressure of a predetermined pressure or more is generated, the vent part opens to release the internal pressure.

[0004] Japanese Patent Application Laid-Open No. 2005-178813

[0005] By the way, the peelable tape used for the moldability of the vent part is preferably transported in a wound (wound) state from the viewpoints of production efficiency and ease of transportation. However, when winding the peelable tape, misalignment or collapse of the winding may occur, or it may not be wound properly, and in some cases, it may be difficult to correct the misaligned winding. Furthermore, when the winding of the peelable tape is misaligned, there is also a problem that alignment is not successful in the production of the packaging bag, resulting in a decrease in the production efficiency of the packaging bag.

[0006] Therefore, the present invention aims to provide an easy-peel tape and a winding thereof that are less prone to winding misalignment or collapse when wound, and that can be easily corrected even if winding misalignment occurs. Another objective is to provide a heat-treated packaging bag using the easy-peel tape of the present invention.

[0007] The release tape according to the present invention is composed of a laminate having a base layer and an easy-release layer, and the surface friction coefficient between the surface and the back surface of the laminate at 23°C is 0.2 to 2.0. The winding body according to the present invention is a winding of the easy-release tape. The heat-treated packaging bag according to the present invention is a heat-treated packaging bag for heat-treating contents, and has a steam-permeable section that allows steam to pass through when the internal pressure rises due to the heat-treating of the contents, and the steam-permeable section comprises two films and the easy-release tape of the present invention inserted between the two films.

[0008] According to the present invention, it is possible to provide an easily peelable tape that is less prone to winding misalignment or collapse when wound, and even if winding misalignment occurs, the misalignment can be easily corrected, a wound body thereof, and a heat treatment packaging bag using the easily peelable tape.

[0009] This is a cross-sectional view showing the configuration of one embodiment of the easy-peel tape according to the present invention. This is a cross-sectional view showing the configuration of another embodiment of the easy-peel tape according to the present invention. This is a perspective view showing an example of a winding of the easy-peel tape according to the present invention. This is a schematic front view showing the configuration of a heat treatment packaging bag according to one embodiment of the present invention. This is a schematic exploded perspective view showing the configuration of a heat treatment packaging bag according to one embodiment of the present invention.

[0010] <Easy-Peel Tape> An embodiment of the easy-peel tape and its winding body according to the present invention will be described with reference to the drawings. The easy-peel tape according to the present invention is preferably used for applications where the seal strength is partially reduced when sealing films together, and is particularly preferably used for forming the steam-permeable portion of a heat-treated packaging bag, which will be described later.

[0011] Figure 1 is a cross-sectional view showing the configuration of one embodiment of the easy-peel tape according to the present invention. Figure 2 is a cross-sectional view showing the configuration of another embodiment of the easy-peel tape according to the present invention. Figure 3 is a perspective view showing an example of a winding body made by winding the easy-peel tape according to the present invention.

[0012] As shown in Figure 1, the easy-peel tape 4 is composed of a laminate having a base layer 41 and an easy-peel layer 42. Furthermore, by winding (winding) this easy-peel tape 4, it becomes a wound body 40 as shown in Figure 3. In the present invention, the surface friction coefficient at 23°C between the front and back surfaces of the laminated easy-peel tape 4 is 0.2 to 2.0. With this configuration, when winding the easy-peel tape 4, winding misalignment and winding collapse are less likely to occur, and even if winding misalignment occurs, the misalignment can be easily corrected. In addition, when forming the steam-permeable section 31 of the heat-treated packaging bag 1 described later, positional misalignment is less likely to occur, improving manufacturing efficiency. The surface friction coefficient at 23°C between the front and back surfaces of the laminated easy-peel tape 4 is more preferably 0.2 to 1.4, and even more preferably 0.25 to 1.33. The surface friction coefficient refers to the static friction coefficient measured according to JIS P8147. The surface friction coefficient can be adjusted as appropriate by changing the surface roughness of the base layer 41 and the easily peelable layer 42.

[0013] Furthermore, the tensile strength (MD) of the easy-peel tape 4 at 23°C is preferably 20 to 80 MPa, more preferably 22 to 70 MPa, and even more preferably 23 to 62 MPa. Also, the tensile elongation (MD) of the easy-peel tape 4 at 23°C is preferably 90 to 850%, more preferably 120 to 800%, and even more preferably 150 to 750%. By having the tensile strength and tensile elongation within these ranges, it is possible to effectively suppress the stretching of the easy-peel tape 4 when it is pulled out from the winding body 40. As a result, it is possible to more effectively prevent misalignment when forming the steam-permeable portion 31 of the heat-treated packaging bag 1 described later, and manufacturing efficiency is further improved.

[0014] The tape thickness of the easy-peel tape 4 is preferably 100 μm or less, more preferably 10 to 80 μm, and even more preferably 20 to 70 μm. This more effectively prevents poor steam passage caused by the bulkiness of the steam passage portion 31 of the heat-treated packaging bag 1, which will be described later. The tape width of the easy-peel tape 4 is preferably 5 to 50 mm, more preferably 7 to 30 mm, and even more preferably 10 to 20 mm. This improves the handling ease when forming the steam passage portion 31 of the heat-treated packaging bag 1, which will be described later.

[0015] The base layer 41 has the function of supporting the easily peelable layer 42. Materials that can constitute the base layer 41 include, for example, polyolefins such as polyethylene and polypropylene; halogenated polyolefins such as polyvinylidene chloride and polyvinylidene fluoride; polyvinyl alcohol; polyamides such as nylon 6, nylon 6,6 and polymetaxylylene adipamide; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; polyacrylic acid esters such as poly(meth)acrylate, poly(meth)acrylate, and poly(meth)acrylate; and copolymers of monomers forming these. Furthermore, a stretched film obtained by uniaxial stretching or biaxial stretching of a film composed of the above materials can be used as the base layer 41. The thickness of the base layer 41 is preferably 10 to 90 μm, more preferably 15 to 70 μm, and even more preferably 20 to 50 μm.

[0016] As the material constituting the easily peelable layer 42, for example, polyolefins (for example, polyethylene with a melting point of 120°C or less (preferably 110°C or less), polypropylene with a melting point of 140°C or less (preferably 130°C or less), or blends thereof) can be used. The melting point is a value measured according to ASTM 2117. When retort sterilization is performed as heat sterilization, it is preferable that the easily peelable layer 42 is mainly composed of polypropylene, and when boiling sterilization is performed as heat sterilization, it is preferable that the easily peelable layer 42 is mainly composed of polyethylene. The thickness of the easily peelable layer 42 is preferably 1 to 20 μm, more preferably 3 to 15 μm, and even more preferably 5 to 10 μm.

[0017] Furthermore, as shown in Figure 2, the easy-peel tape 4 may have a strong adhesive layer 43 on the side of the base layer 41 opposite to the easy-peel layer 42. In particular, when polyethylene is used as the material for the easy-peel layer 42, it is preferable to have this strong adhesive layer 43. This makes it possible to more reliably cause peeling of the easy-peel layer 42 in the steam-permeable section 31 formed using the easy-peel tape 4, regardless of the type of other constituent films of the heat-treated packaging bag 1. As the material constituting the strong adhesive layer 43, for example, linear low-density polyethylene or metallocene polyethylene can be used. In such cases, it is preferable that the base layer is a stretched film made of the above material. The easy-peel tape 4 may also have layers with any other functions besides the base layer 41, easy-peel layer 42, and strong adhesive layer 43 described above.

[0018] <Heat Treatment Packaging Bag> Next, an embodiment of the heat treatment packaging bag according to the present invention will be described with reference to the drawings. The heat treatment packaging bag according to the present invention is suitable for use when heating the contents in a microwave oven, and is also suitable for use when heating food ingredients.

[0019] Figure 4 is a schematic front view showing the configuration of a heat-treated packaging bag according to one embodiment of the present invention. Figure 5 is a schematic exploded perspective view showing the configuration of a heat-treated packaging bag according to one embodiment of the present invention. In the following description, the upper side in Figure 4 will be referred to as "top" and the lower side as "bottom".

[0020] The heat-treated packaging bag 1 consists of a bag body 10 made of packaging bag film and a gusseted seal portion 30 that releases pressure when the internal pressure rises due to the heat treatment of the contents.

[0021] Considering that the packaging bag film constituting the bag body 10 will be subjected to heat treatment by a microwave oven, it is preferable that it be made of a plastic material that has heat resistance to microwave heating. Specific examples of such plastic materials include polyolefins such as polyethylene and polypropylene; halogenated polyolefins such as polyvinylidene chloride and polyvinylidene fluoride; polyvinyl alcohol; polyamides such as nylon 6, nylon 6,6 and polymetaxylylene adipamide; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; polyacrylic acid esters such as poly(meth)acrylate, poly(meth)acrylate, and poly(meth)acrylate; and copolymers of monomers that form these. Note that "(meth)acrylic" means methacrylic or acrylic.

[0022] Specific examples of polyethylene include linear low-density polyethylene, high-pressure low-density polyethylene, high-density polyethylene, and metallocene polyethylene. Specific examples of polypropylene include propylene homopolymers and random or block copolymers of propylene with ethylene or 1-butene.

[0023] The packaging bag film may be a single layer, or it may be laminated in two or more layers by co-extrusion or the like. For example, the packaging bag film preferably consists of a base layer and a sealant layer, and may also have other layers between the base layer and the sealant layer.

[0024] For the base layer of the packaging bag film, for example, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide, and polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate can be used. For the sealant layer, for example, polyolefins such as polyethylene and polypropylene can be used. Furthermore, for the intermediate layer provided between the base layer and the sealant layer, for example, the above-mentioned polyamides and polyesters can be used.

[0025] Furthermore, if the packaging bag film is composed of multiple layers, it is preferable that at least one of the layers is made of polyester, and more preferably of polyethylene terephthalate. This makes it possible to improve the heat resistance of the packaging bag film while more easily achieving an appropriate level of stiffness.

[0026] Furthermore, the packaging bag film may be a gas-barrier composite film coated with an inorganic oxide thin film such as aluminum oxide or silicon oxide. This composite film can be obtained by heating and vaporizing aluminum oxide or silicon oxide, either individually or as a mixture, under vacuum and depositing it onto the surface of the film. In addition, the packaging bag film may have a gas-barrier adhesive layer, such as one mainly composed of polyepoxy resin, or a gas-barrier layer, such as a polyvinyl alcohol-based polymer resin, cellulose, or urethane-based resin.

[0027] The heat-treated packaging bag 1 can take any form as long as it is configured to allow the contents to be placed inside and sealed. In other words, the bag 10 can take any form, including a three-sided seal as shown in Figure 4, a four-sided seal, a stick, a pillow, a gusset, an envelope seal, a standing seal, a gusset seal, etc. The shape of the outer edge of the heat-treated packaging body 1 can be a polygon such as a triangle, square, or pentagon, a circle, an ellipse, or a combination thereof, but it is generally a square.

[0028] The bag body 10 is composed of, for example, an upper surface film 11a, a lower surface film 11b, and a back surface film 12, as shown in Figures 4 and 5. Furthermore, it has a peripheral seal portion 15 that seals the edges (sides and bottom) of these parts while forming a gusset seal portion 30. The bag body 10 may also be provided with a bottom to allow it to stand on its own. The seal width of the peripheral seal portion 15 formed on the sides and bottom of the bag body 10 can be set as appropriate.

[0029] The peripheral seal portion 15 may be completely sealed at room temperature and in a 90°C atmosphere, but it may also be easily opened if its seal strength is stronger than that of the permeable portion 31 described later. When the peripheral seal portion 15 is easily opened, the seal strength at room temperature and in a 90°C atmosphere is preferably 10 to 50 N / 15 mm, and more preferably 12 to 45 N / 15 mm. The seal strength at room temperature and in a 90°C atmosphere is the value measured at room temperature and in a 90°C atmosphere, respectively, in accordance with JIS Z0238 "Test method for sealed flexible packaging bags".

[0030] In this embodiment, on one side of the bag 10 (the front side in Figure 4), a gable seal portion 30 and a steam-permeable portion 31 are formed by joining the upper surface film 11a and the lower surface film 11b facing each other and sandwiching the easy-peel tape 4 of the present invention described above. That is, the steam-permeable portion 31 is formed by inserting and sandwiching the easy-peel tape 4 described above between the two films, the upper surface film 11a and the lower surface film 11b. In this embodiment, the steam-permeable portion 31 is provided approximately in the center of the gable seal portion 30, and the steam-permeable portion 31 has the function of releasing the pressure when the internal pressure rises due to the heat treatment of the contents. The gable seal portion 30 is formed to protrude outward from one side of the bag 10. Preferably, the gable seal portion 30 is formed approximately parallel to one side of the heat-treated packaging body 1. Note that the gable seal portion 30 is not required, in which case the steam-permeable portion 31 may be provided in any of the peripheral seal portions 15.

[0031] The steam-permeable section 31 has weaker opening properties than the peripheral seal section 15 in a 90°C atmosphere. This allows the steam-permeable section 31 to open before the peripheral seal section 15 opens when the contents 2 are heat-treated and the internal pressure of the heat-treated packaging 1 rises, thereby releasing the pressure through the steam-permeable section 31.

[0032] The heat seal strength of the steam-permeable section 31 in a 90°C atmosphere is preferably 12 N / 15 mm or less, and more preferably 8 N / 15 mm or less. The heat seal strength of the steam-permeable section 31 in a 90°C atmosphere may be 0 N / 15 mm, but is preferably 1 N / 15 mm or more. The steam-permeable section 31 may be completely sealed at room temperature and may also be easily opened. The seal strength of the steam-permeable section 31 at room temperature is preferably 0.5 to 30 N / 15 mm, and more preferably 1 to 25 N / 15 mm. Preferred embodiments of the present invention have been described above, but the present invention is not limited thereto.

[0033] <Example 1> An easy-peel tape 4 (tape width: 17 mm, tape thickness: 50 μm) with the layer configuration shown in Figure 1 was prepared. The composition of the easy-peel tape 4 was a base layer 41 (45 μm): polypropylene base layer, and an easy-peel layer 42 (5 μm): polypropylene mixed resin layer. The surface friction coefficient between the front and back surfaces of the easy-peel tape 4 at 23°C was 0.62. The tensile strength of the easy-peel tape 4 at 23°C was 43.6 MPa, and the tensile elongation at 23°C was 569%.

[0034] <Example 2> An easy-peel tape 4 (tape width: 17 mm, tape thickness: 60 μm) with the layer configuration shown in Figure 2 was prepared. The easy-peel tape 4 consisted of a strong adhesive layer 43 (30 μm): polyethylene layer, a base layer 41 (12 μm): polyethylene terephthalate layer, and an easy-peel layer 42 (18 μm): polyethylene mixed resin layer. The surface friction coefficient between the front and back surfaces of the easy-peel tape 4 at 23°C was 0.28. The tensile strength of the easy-peel tape 4 at 23°C was 59 MPa, and the tensile elongation at 23°C was 155%.

[0035] <Example 3> An easy-peel tape 4 (tape width: 17 mm, tape thickness: 50 μm) with the layer configuration shown in Figure 1 was prepared. The composition of the easy-peel tape 4 was: base layer 41 (45 μm): polyethylene base layer, easy-peel layer 42 (5 μm): polyethylene mixed resin layer. The surface friction coefficient between the front and back surfaces of the easy-peel tape 4 at 23°C was 1.32. The tensile strength of the easy-peel tape 4 at 23°C was 51 MPa, and the tensile elongation at 23°C was 681%.

[0036] <Example 4> An easy-peel tape 4 (tape width: 17 mm, tape thickness: 45 μm) with the layer configuration shown in Figure 1 was prepared. The composition of the easy-peel tape 4 was: base layer 41 (30 μm): polyethylene base layer, easy-peel layer 42 (15 μm): polyethylene mixed resin layer. The surface friction coefficient between the front and back surfaces of the easy-peel tape 4 at 23°C was 1.20. The tensile strength of the easy-peel tape 4 at 23°C was 26 MPa, and the tensile elongation at 23°C was 566%.

[0037] <Example 5> An easy-peel tape 4 (tape width: 17 mm, tape thickness: 68 μm) with the layer configuration shown in Figure 1 was prepared. The composition of the easy-peel tape 4 was as follows: base layer 41 (50 μm): "polyethylene base layer (20 μm), polyamide base layer (10 μm), polyamide base layer (20 μm)", easy-peel layer 42 (18 μm): polyethylene mixed resin layer. The surface friction coefficient between the front and back surfaces of the easy-peel tape 4 at 23°C was 0.2. The tensile strength of the easy-peel tape 4 at 23°C was 32 MPa, and the tensile elongation at 23°C was 466%.

[0038] <Comparative Example 1> An easy-peel tape 4 (tape width: 17 mm, tape thickness: 50 μm) with the layer configuration shown in Figure 1 was prepared. The composition of the easy-peel tape 4 was: base layer 41 (45 μm): polyethylene base layer, easy-peel layer 42 (5 μm): polyethylene mixed resin layer. The surface friction coefficient between the front and back surfaces of the easy-peel tape 4 at 23°C was 0.15. The tensile strength of the easy-peel tape 4 at 23°C was 20 MPa, and the tensile elongation at 23°C was 537%.

[0039] <Comparative Example 2> An easy-peel tape 4 (tape width: 17 mm, tape thickness: 30 μm) with the layer configuration shown in Figure 1 was prepared. The composition of the easy-peel tape 4 was: base layer 41 (15 μm): polyethylene base layer, easy-peel layer 42 (15 μm): EVA mixed resin layer. The surface friction coefficient between the front and back surfaces of the easy-peel tape 4 at 23°C was 2.2. The tensile strength of the easy-peel tape 4 at 23°C was 29 MPa, and the tensile elongation at 23°C was 611%.

[0040] <Evaluation> The easy-peel tape 4 of each example and comparative example was wound up, and the ease of winding was evaluated according to the following three criteria: A: Even if winding misalignment occurred, it could be easily corrected, and there was no winding collapse. B: There was no winding collapse, but when winding misalignment occurred, it was difficult to correct the misalignment. C: It could not be wound properly, and winding collapse occurred. These results are shown in Table 1.

[0041]

[0042] As can be seen from Table 1, the easy-peel tapes of the examples were less prone to winding misalignment or collapse when wound, and even if winding misalignment occurred, it could be easily corrected. Furthermore, when heat treatment packaging bags were manufactured using the windings of the easy-peel tapes of each example, the windings of the easy-peel tapes of the examples were less prone to positional misalignment in the formation of the steam passage section 31, resulting in high yield and high productivity.

[0043] 1 Heat-treated packaging bag 4 Easy-release tape 10 Bag body 11 First film 11a Upper surface film 11b Lower surface film 12 Second film 15 Peripheral seal section 30 Gusset seal section 31 Steam-permeable section 40 Winding section 41 Base layer 42 Easy-release layer 43 Strong adhesive layer

Claims

1. An easy-peel tape comprising a laminate having a base layer and an easy-peel layer, wherein the surface friction coefficient between the surface and back surface of the laminate at 23°C is 0.2 to 2.

0.

2. The easy-peel tape according to claim 1, wherein the tensile strength (MD) at 23°C is 20 to 80 MPa.

3. The easy-peel tape according to claim 1, wherein the tensile elongation (MD) at 23°C is 90 to 850%.

4. The easy-peel tape according to claim 1, wherein the tape thickness is 100 μm or less.

5. The easy-peel tape according to claim 1, wherein the tape width is 5 to 50 mm.

6. The easy-peel tape according to claim 1, having a strong adhesive layer on the side of the base layer opposite to the easy-peel layer.

7. A winding body in which the easily peelable tape described in any one of claims 1 to 6 is wound.

8. A heat-treated packaging bag for heat-treating contents, having a steam-permeable section for allowing steam to pass through when the internal pressure rises due to the heat-treating of the contents, wherein the steam-permeable section comprises two films and an easily removable tape according to any one of claims 1 to 6 inserted between the two films.

9. A heat-treated packaging bag according to claim 8, comprising a bag-shaped bag body having a first film and a second film facing each other, and a gusseted seal portion provided so as to protrude outward from the first film, wherein the gusseted seal portion comprises the steam-permeable portion.

Images