Packaging

Abstract

To provide a package in which a small hole for releasing vapor is to be readily formed during cooking with an electronic oven despite employing nylon.SOLUTION: A package 1 comprises an on-back seal part 3a that is heat-sealed in a convex form and end seal parts 3b and 3c that are heat-sealed in a manner crossing orthogonally thereto, in which a pair of unsealing guides 5 and 5 are provided for capturing a tear in progress upon pulling and unsealing an unsealing-start point 7 provided in the on-back seal part 3a as a start point and guiding the progress. A heat-sealable resin layer provided for heat sealing has a Young's modulus (tensile elasticity modulus), as indicated as an inclination of a linear line in an elastic deformation range of a stress-strain curve, of 0.2 giga-Pascal (GPa) or greater in measurement conforming to JIS K7127.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a package.

Background Art

[0002] Conventionally, a so-called pillow package in which a single packaging material is formed into a tubular shape to form a gusseted back seal portion, the contents are accommodated in the internal space thereof, and the top and bottom thereof are sealed has been used for various applications. As one method of opening a package having such a structure, there is a method of providing an opening start portion in the back seal portion and tearing it in one direction from there. For example, in the package disclosed in Patent Document 1, a tear of the packaging material starting from the opening start portion provided in the back seal portion is captured by opening guide lines provided on both sides of the back seal portion, and the opening proceeds along the opening guide lines. Thereby, an opening suitable for the contents can be obtained.

[0003] On the other hand, it is known that cooked or semi-cooked food is accommodated in a packaging container capable of being stored at normal temperature, low temperature, or frozen, and heated in a microwave oven without opening it during cooking. For example, in the packaging container disclosed in Patent Document 2, a weakened portion is provided in a part of the packaging container, and small holes for steam release are formed in the weakened portion due to an increase in internal pressure accompanying heating, thereby preventing the packaging container from bursting while sufficiently steaming the food.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a material for constructing packaging, nylon is superior to polyethylene terephthalate, for example, in terms of tear resistance when opened. However, as a material for packaging for microwave cooking, it is difficult to form small holes for steam venting with nylon. Therefore, the present invention aims to provide packaging that uses nylon while easily forming small holes for steam venting during microwave cooking. [Means for solving the problem]

[0006] The inventors' research using a nylon packaging material revealed that the high hygroscopicity of nylon makes it difficult to form small holes for steam release (hereinafter referred to as "steam vents") during microwave cooking. This weakens the support force for the heat-sealable resin layer around the fragile processed area, causing the heat-sealable resin layer to stretch easily.

[0007] Based on this finding, the present invention provides a package comprising: a back-sealed portion formed by heat-sealing a pair of substantially parallel ends of a substantially rectangular packaging material in a gable shape; and end-sealed portions formed by heat-sealing the other pair of ends of the packaging material perpendicular to the back-sealed portion, wherein the packaging material is a laminate having a base layer made of uniaxially stretched nylon film and a heat-sealable resin layer, the back-sealed portion is provided with an opening start portion, and a pair of opening guide portions are provided on either side of the back-sealed portion and within a range from the position of the back-sealed portion to a position that does not wrap around to the back side when the package is opened by pulling in the extending direction of the back-sealed portion starting from the opening start portion, for capturing the tear that progresses when the package is opened by pulling in the extending direction of the back-sealed portion starting from the opening start portion and guiding the progress of the tear, the opening guide portions are provided on either side of the back-sealed portion and within a range from the position of the back-sealed portion to a position that does not wrap around to the back side when the package is viewed from the back-sealed portion side, the opening guide portions are cut lines provided to the extent that they do not penetrate the packaging material, and the heat-sealable resin layer ,Response Force-Distortion In the elastic deformation range of the curve The present invention provides a packaging material in which the Young's modulus (tensile modulus), expressed as the slope of a straight line, is 0.2 gigapascals (GPa) or greater, as measured in accordance with JIS K7127.

[0008] This packaging allows for proper steaming during microwave cooking, preventing bursting due to increased internal pressure and ensuring the food is thoroughly steamed. Furthermore, the base layer of the packaging is made of nylon film, providing good tear resistance. Additionally, because the packaging can be opened along the opening guide, a wide opening can be achieved depending on the shape of the guide, allowing the packaging to double as tableware.

[0009] In this packaging, the direction of extension of the back seal portion may coincide with the stretching direction of the nylon film. In this case, the pulling direction when opening coincides with the stretching direction of the nylon film, making it easier to tear in that direction.

[0010] In this packaging, the opening guide may have a shape that moves away from the back seal as the tear progresses. In this case, a wider opening can be made, making it easier to remove the contents.

[0011] In this packaging, the laminate is targeted to the portion where the opening guide is provided. ,Response Force-Distortion In the elastic deformation range of the curve The Young's modulus (tensile modulus), expressed as the slope of a straight line, may be 0.45 gigapascals (GPa) or greater in measurements conforming to JIS K7127.

[0012] The opening guide section may consist of a continuous line, dashed line, dotted line, or a combination thereof, formed by laser processing.

[0013] The opening guide portion may be positioned so that its two ends straddle the opening start portion in the direction of extension of the back seal portion. In this case, when opening starting from the opening start portion, the opening guide portion can easily catch the tear at the beginning of opening. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a packaging material that uses nylon and in which small holes for steam release are easily formed during microwave cooking. [Brief explanation of the drawing]

[0015] [Figure 1] (A) is a diagram showing the external appearance of the packaging. (B) is a plan view of the packaging material before it is formed into the packaging shown in (A). [Figure 2] This is a perspective view of a package being opened. [Figure 3] This is a perspective view of the package after it has been opened. [Modes for carrying out the invention]

[0016] The present invention relates to a so-called pillow-type packaging. This packaging contains food inside, and by forming a steam vent in a part of the packaging during microwave cooking, it is possible to prevent bursting due to internal pressure. Furthermore, after cooking, it is possible to easily open the packaging from the opening start point provided on the back seal, forming an opening with a relatively large opening width in the longitudinal direction of the packaging, making it easy to remove the food, and the packaging material can also be used as tableware. Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In each figure, the same parts or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.

[0017] As shown in Figure 1, the packaging body 1 of this embodiment is a bag that seals food inside, and comprises a back seal portion 3a formed by heat sealing in a gusset shape, and two end seal portions 3b and 3c that are heat-sealed perpendicular to the back seal portion 3a. The portion other than the back seal portion 3a and the end seal portions 3b and 3c constitutes the body portion 4, which is the part that contains the food. The side with the back seal portion 3a and the side without the back seal portion 3a form the front and back of the packaging body 1, and the portion connecting these two sides constitutes a gusset corresponding to the thickness of the packaging body 1. The back seal portion 3a is provided with a notch 7, which is the opening start portion, at a position closer to the end seal portion 3b side.

[0018] When viewed from the side of the back seal part 3a, the package 1 is provided with a pair of unsealing guide lines (unsealing guide parts) 5, 5 that are line symmetric so as to sandwich the back seal part 3a from both sides with the base part 6 of the back seal part 3a as the center line. Here, the base part 6 refers to the boundary between the back seal part 3a and the body part 4. The unsealing guide lines 5, 5 are within the range from the base part 6 to a position that does not wrap around to the back side of the body part 4 (here, up to just before reaching the flange of the body part 4) when the package 1 is viewed from the side of the back seal part 3a. The details of the unsealing guide lines 5, 5 will be described later.

[0019] Here, the packaging material 100, which is the constituent material of the package 1, is a rectangular resin sheet made of a laminate of resin films. The packaging material 100 before forming the package 1 has a heat seal planned part 3 that is bordered in a band shape in all its peripheral regions. That is, the heat seal planned part 3 extends along the entire perimeter of the rectangle with a predetermined distance that enters from the rectangular edge into the inside of the rectangle as the width. In Fig. 1(B), the illustrated surface where the unsealing guide lines 5, 5 are provided is the outer surface side of the package 1, and the illustrated back surface is the inner surface side of the package 1. The heat seal planned part 3 is on the illustrated back surface. In Fig. 1(B), the back seal part 3a is formed by heat sealing a pair of both ends that are parallel to each other and extend in the illustrated up and down direction and are in the illustrated left and right direction of the packaging material 100 in a palm-like manner.

[0020] The laminate constituting the packaging material 100 includes at least a base material layer made of a uniaxially stretched nylon film and a heat sealable resin layer. The heat sealable resin layer is laminated as the innermost layer of the package 1. Between the base material layer and the heat sealable resin layer, an adhesive for bonding the two or a printing layer may be provided. In addition, a gas barrier layer, a light shielding layer, an ultraviolet absorption layer, etc. may be provided.

[0021] The thickness of the uniaxially stretched nylon film is, for example, 10 μm to 30 μm. The uniaxial stretching direction of the uniaxially stretched nylon film coincides with the extending direction of the back seal part 3a of the package 1.

[0022] As the heat-sealable resin layer (sealant), polyolefin resins such as polyethylene resin and polypropylene resin are the most commonly used. Among polyethylene resins, low-density polyethylene and linear low-density polyethylene are preferred. In particular, in the case of packaging 1 of this embodiment, linear low-density polyethylene copolymerized using a Ziegler-Natta catalyst with C4 (butene-1) as a comonomer is preferred. This polyethylene has good tearability and, when heated in a microwave oven, the opening guide lines 5,5 partially break and open, easily forming a vent that functions as a steam release. The heat-sealable resin layer may be laminated by melting the resin and extruding it onto the base layer, or a film may be formed and laminated.

[0023] In this embodiment, the heat-sealable resin layer is ,Response Force-Distortion In the elastic deformation range of the curve The Young's modulus (tensile modulus), expressed as the slope of a straight line, is 0.2 gigapascals (GPa) or higher in measurements according to JIS K7127. This Young's modulus may be 0.3 gigapascals or higher, or 0.4 gigapascals or higher. When the Young's modulus is within this range, the heat-sealable resin layer is less likely to stretch, and vents are more easily formed when heated in a microwave oven.

[0024] The thickness of the heat-sealable resin layer may be, for example, 10 μm to 50 μm, or 20 μm to 40 μm.

[0025] Furthermore, regarding laminates ,Response Force-Distortion In the elastic deformation range of the curve It is preferable that the Young's modulus (tensile modulus), expressed as the slope of a straight line, is 0.45 gigapascals (GPa) or higher in measurements in accordance with JIS K7127. In this measurement, a sample with an opening guide line 5 is prepared and used as the measurement target, and two points (two points perpendicular to the direction of elongation, which will be described later as a cut line) straddling the opening guide line 5 are pulled. When the value of this Young's modulus is 0.45 gigapascals or higher, the elongation of the laminate due to internal pressure (to the extent that it can withstand the bursting of the packaging 1) and the formation of the steam vents are more easily balanced when heated in a microwave oven.

[0026] The opening guide lines 5,5 are cut lines provided to a depth that does not penetrate the packaging material 100. In this embodiment, each of the opening guide lines 5,5 consists of three parts, each being a straight line. Specifically, each of the opening guide lines 5,5 consists of a first parallel section 5a that extends parallel to the extending direction of the back sealing section 3a on the side closer to the end sealing section 3b and closer to the base 6 of the back sealing section 3a; a transverse section 5b that continues from the endpoint of the first parallel section 5a on the end sealing section 3c side and extends toward the end sealing section 3c and away from the back sealing section 3a; and a second parallel section 5c that continues from the endpoint of the transverse section 5b on the end sealing section 3c side and extends parallel to the extending direction of the back sealing section 3a. Here, the first parallel section 5a is positioned to encompass the location of the notch 7 in the extending direction of the back-sealed section 3a, and the endpoint of the second parallel section 5c is located at a position that does not reach the center of the extending width of the back-sealed section 3a.

[0027] The depth of the cuts in the opening guide lines 5,5 should be such that the portion in question is weaker than the rest of the packaging material 100, and should not penetrate the packaging material 100 (so-called "half-cuts"). For example, the cuts may be formed so that only layers other than the heat-sealable resin layer are cut. Such cut lines can be formed by using a cutting tool such as a die cutter or rotary die cutter, or by using a laser processing machine such as a carbon dioxide laser. In the case of laser processing, a wide cut line can be formed by melting the material according to the laser line width. The width of the cut line formed by melting the material is, for example, 50 to 300 μm, preferably 100 to 250 μm. 。

[0028] The packaging 1 allows the food contained inside to be heated and steamed by microwave cooking. Normally, when a sealed packaging is heated, the internal pressure increases and the packaging bursts. However, in the packaging 1 of this embodiment, when the internal pressure increases and the packaging swells, and tension is applied to the entire body 4, the opening guide lines 5, 5, which are considered weak against tensile stress, partially break, and a steam vent is formed. Steam is released from the steam vent, which lowers the internal pressure and prevents the packaging 1 from bursting, and the steam that fills the inside allows the food to be steamed.

[0029] When opening the package 1, first raise the back seal portion 3a, which is in a fallen position. Next, pinch both sides of the notch 7 in the back seal portion 3a with your fingers and pull toward the end seal portion 3c to begin tearing the package 1. When tearing starts from the notch 7, the tear 9 descends the back seal portion 3a toward the body portion 4 and reaches the base portion 6, where it splits into two branches and progresses, forming an opening 11 as it reaches the first parallel portions 5a, 5a. In other words, the first parallel portions 5a, 5a capture the progressing tear 9. If tearing continues thereafter (Figure 2), the tear 9 is sequentially guided and progresses toward the first parallel portions 5a, 5a, the transverse portions 5b, 5b, and the second parallel portions 5c, 5c, until it reaches the end of the second parallel portions 5c, 5c. Furthermore, if the tearing continues towards the end seal portion 3c, the tear 9 progresses linearly in the area where there are no opening guide lines 5,5, and a large opening 11 can be formed (Figure 3). This makes it easier to remove the food 13. Also, because the opening 11 is large enough, the packaging material can double as tableware, eliminating the need to transfer the food 13 to another dish.

[0030] In this series of microwave cooking and opening procedures, the Young's modulus of the heat-sealable resin layer of the packaging material constituting the package 1 is 0.2 gigapascals (GPa) or higher, so that the steam vents are properly formed. In conventional packaging materials used in packaging bodies, the high hygroscopicity of the nylon film base material weakens the support force for the heat-sealable resin layer in the areas where the opening guide lines 5,5 are provided, causing the heat-sealable resin layer to stretch and making it difficult to form the steam vents. However, in the packaging body 1 of this embodiment, even if the uniaxially oriented nylon film absorbs moisture, the steam vents are properly formed.

[0031] Furthermore, when opening, the first parallel sections 5a, 5a are positioned to encompass the location of the notch 7 in the extending direction of the back seal section 3a, making it easy for the first parallel sections 5a, 5a to capture the tear 9 that has branched out from the base 6. In addition, since the base layer of the packaging material is made of uniaxially oriented nylon film and its stretching direction coincides with the tearing direction, it is easy to tear in a straight line even after the opening guide lines 5, 5 have finished guiding the tear.

[0032] Although preferred embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments. For example, in the above embodiments, a package with a gusset in the body was used as an example, but it may also have a shape without a gusset. Also, in the above embodiments, the shape of the opening guide line was made up of a continuous line consisting of three straight parts, but it may also be made up of a curve, and may consist not only of a continuous line but also of a dashed line, a dotted line, or a combination thereof. Also, in the above embodiments, the two opening guide lines are symmetrical with respect to the back seal portion, but they may be asymmetrical. [Examples]

[0033] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

[0034] <Materials used> (base material layer) • Uniaxially oriented nylon A Uniaxially oriented nylon film. Product name: "Uniathlon," manufactured by Idemitsu Unitech Co., Ltd. Thickness: 15 μm. • Uniaxially oriented nylon B Uniaxially oriented nylon film. Product name: "Emblem NC", manufactured by Unitika Ltd. Thickness: 15 μm. • Biaxially oriented nylon Biaxially oriented nylon film. Product name: "Emblem ONU", manufactured by Unitika Ltd. Thickness: 25 μm. ·Uniaxially oriented PET Uniaxially oriented polyethylene terephthalate film. Product name: "Emblet PC", manufactured by Unitika Ltd. Thickness: 12 μm.

[0035] (Heat-sealable resin layer) Linear low-density polyethylene copolymerized with C4 (butene-1) as a comonomer using a Ziegler-Natta catalyst was used. • LLDPE (KF101) Linear low-density polyethylene. Product name "KF101", manufactured by Skyfilm Co., Ltd. Thickness 40 μm. Young's modulus 0.40 GPa. • LLDPE (KF201) Linear low-density polyethylene. Product name "KF201", manufactured by Skyfilm Co., Ltd. Thickness 40 μm. Young's modulus 0.22 GPa. • LLDPE (XMTN) Linear low-density polyethylene. Product name "XMTN", manufactured by Futamura Chemical Co., Ltd. Thickness 40 μm. Young's modulus 0.16 GPa. • LLDPE (HR611) Linear low-density polyethylene. Product name "HR611", manufactured by Skyfilm Co., Ltd. Thickness 40 μm. Young's modulus 0.17 GPa.

[0036] <Example 1> (Fabrication of laminates) A uniaxially oriented nylon A was printed using the ink "Riogran" (product name, manufactured by Toyo Ink Co., Ltd.). A heat-sealable resin layer "LLDPE (KF101)" was then bonded to this printed surface using adhesives "Takelac A626" (product name, manufactured by Mitsui Chemicals, Inc.) and "Takenate A50" (product name, manufactured by Mitsui Chemicals, Inc.) to create a laminate.

[0037] (Measurement of Young's modulus of laminated material) A laminate was prepared as a sample for measuring Young's modulus. A carbon dioxide laser was irradiated from the side of the uniaxially oriented nylon A in the TD direction (output 25W, scan speed 800 mm / sec) to form a brittleness line (opening guide line) that did not penetrate the heat-sealable resin layer. The sample was cut to a width of 15 mm so that the MD direction was the longitudinal direction, and it was pulled with a chuck distance of 50 mm and a tensile speed of 200 m / min so that the brittleness area was in the center of the test piece, and the Young's modulus was calculated (according to JIS K 7127).

[0038] (Formation of packaging) A carbon dioxide laser was irradiated from the substrate layer side (output 25W, scan speed 800mm / sec) to form an opening guide line that does not penetrate the heat-sealable resin layer, resulting in the shape shown in Figure 1(B). The area of ​​existence in the vertical direction was 50mm, and the area of ​​existence in the horizontal direction was 70mm. 200g of frozen fried rice was filled inside, and each end was heat-sealed to the shape shown in Figure 1(A) to obtain a package. An eye notch was provided in the back seal portion. The dimensions of the package were 155mm × 250mm × 20mm.

[0039] <Examples 2, 3 and Comparative Examples 1-5> A packaging was prepared in the same manner as in Example 1, using the materials shown in Table 1.

[0040] (Evaluation of microwave cooking and steam permeability) The packaging for Examples 1-3 and Comparative Examples 1-5 was heated in a microwave oven at 1000W for 3 minutes. Separately, the packaging for Examples 1-3 and Comparative Examples 1 and 2 were stored in a constant temperature chamber at 40°C and 90% humidity for four weeks, and then heated in a microwave oven at 1000W for 3 minutes. The steam permeability of each packaging during microwave cooking was checked. If a steam vent was formed and steam escaped normally, it was considered "good." If steam did not escape or if the bag ruptured in a part other than the opening guide line, it was considered "poor."

[0041] (Evaluation of opening inducement) The packaging of Examples 1-3 and Comparative Examples 1-5, which had been microwave-cooked before storage, was torn open from the eye notch. Opening along the opening guide line was considered "good," while opening deviated from the guide line was considered "bad."

[0042] According to the results shown in Table 1, when a uniaxially oriented nylon film is used as the base layer and the Young's modulus of the heat-sealable resin layer is 0.22 GPa or higher, good vapor permeability and tamper-evident properties are obtained.

[0043] [Table 1] [Industrial applicability]

[0044] This invention can be used for packaging materials for microwave cooking. [Explanation of symbols]

[0045] 1...Packaging body, 3...Heat-sealing area, 3a...Back sealing area, 3b,3c...End sealing areas, 4...Body, 5...Opening guide line (opening guide area), 5a...First parallel section, 5b...Cross section, 5c...Second parallel section, 6...Base, 7...Notch (opening start area), 9...Tear, 11...Opening, 13...Food, 100...Packaging material.

Claims

1. A packaging body comprising a back-sealed portion formed by heat-sealing a pair of substantially parallel ends of a roughly rectangular packaging material in a gable shape, and end-sealed portions formed by heat-sealing the other pair of ends of the packaging material perpendicular to the back-sealed portion, The packaging material is a laminate comprising a base layer made of uniaxially stretched nylon film and a heat-sealable resin layer made of linear low-density polyethylene. The aforementioned back seal portion is provided with an opening start section. A pair of opening guides are provided to catch the tear that progresses when the package is opened by pulling in the extending direction of the back seal portion, starting from the opening start portion, and to guide the progression of the tear, sandwiching the back seal portion and within a range from the position of the back seal portion to a position that does not wrap around to the back side when the package is viewed from the back seal portion side. The opening guide portion is a cut line provided so as not to penetrate the packaging material, The heat-sealable resin layer is a packaging material in which the Young's modulus (tensile modulus), expressed as the slope of the straight line in the elastic deformation range of the stress-strain curve, is 0.2 gigapascals (GPa) or more and 0.40 gigapascals (GPa) or less, as measured in accordance with JIS K7127.

2. The packaging according to claim 1, wherein the extending direction of the back-seal portion coincides with the stretching direction of the nylon film.

3. The packaging according to claim 1 or 2, wherein the opening guide portion has a shape that moves away from the back seal portion as the tear progresses.

4. The packaging according to any one of claims 1 to 3, wherein the laminate has a Young's modulus (tensile modulus) of 0.45 gigapascals (GPa) or more, as measured in accordance with JIS K7127, in the stress-strain curve of the portion where the opening guide portion is provided.

5. The packaging according to any one of claims 1 to 4, wherein the opening guide portion consists of a continuous line, dashed line, dotted line, or a combination thereof formed by laser processing.

6. The packaging according to any one of claims 1 to 5, wherein the positions of both ends of the opening guide portion are located such that they sandwich the opening start portion in the extending direction of the back seal portion.

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